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Welcome to Administration Area Design - Overview and Labeling.

2: Administrative Design.

In the previous three lessons we have covered Horizontal, Building Backbone and Campus Backbone designs without detailing administration. This lesson will focus on those principals for both copper and fiber patching in the (ER) equipment room and (TR) telecommunications room but remember other areas may require administration such as the entrance facility. This includes selection of the termination hardware based upon the system requirements, how to determine the space required in these areas for wall or rack mounted termination hardware and understanding what is required in the design of the detailed sketches for the wall fields.

3: Review.

As we have seen ISO and TIA define accommodations (spaces/rooms) and administration hardware. ISO, TIA, and CENELEC refer to these as 'functional elements', using notations, although these may vary among the standards, they map quite well. One exception being that TIA offers the option of an Intermediate Cross-connect (IC), which ISO does not define with a separate name. Throughout this section, the TIA notation shall be in brackets if it differs from that of ISO. The location, configuration and type of hardware used to construct cross-connect fields directly influences and possibly dictates the way in which a distribution system is managed and administered. The ability to make changes easily, in response to relocating personnel and/or equipment within a building, is important related to the increasing costs of making these changes.
Eliminating the need for different types of transmission media from the serving telecommunications room to the work area by standardizing on 4-pair UTP or fiber, is one way of reducing the cost of network rearrangements. Another way to reduce these costs is to allow the customer themselves to make circuit changes at the cross-connect field without the need for highly-trained technicians, so this aspect should be confirmed by the designer at the start of the project.

4: Administration Options - One Point.

Cross-connect field configurations are dictated by the location, system wiring specifications and the hardware selected. Up to three administration points can be designed into the infrastructure according to the standards, but best working practices would normally recommend two.

This small installation here would be considered a one point administration and could be looked after easily by the customer or a technician.

5: Administration Options - Two Points.

With two-point administration, circuits are administered using patch cords at the Building Distributor (MC) located in the equipment room and at Floor Distributors (HC) located in Telecommunications Rooms (TR). This is the most common backbone design with the cross-connects being a high density 110 style or modular RJ45 panels. Equally, this could be an all-fiber backbone design with fiber patch cords and panels.

6: Administration Options - Three Points.

This illustrates the maximum number of administration points recommended by standards, with three patch fields requiring attention to activate a user, which could be viewed as an administration burden. Alternatively, it can be viewed as offering a flexible use of the infrastructure. For example, if this design was a fiber backbone from the IT building to another building, where three TR's cover the distribution, the primary backbone resource could be shared amongst the three TR's.

7: Interconnect & Cross-connect Example TR.

Within the ER or TR, the administration is managed either as cross-connected or interconnected. The example here shows a fiber backbone entering the TR and terminating in a fiber panel (fiber white field) and patching directly to the active hardware port, this is an 'interconnect', known as an FOI (Fiber Optic Interconnect). There could also be some designs with fiber, where it is 'cross-connected' and this would be referred to as an FOC (Fiber Optic Cross-connect). Unless all voice is VoIP, with no BAS, there would probably be a multi-pair copper backbone cable also arriving at the TR. This terminates on a patch panel (copper white field) and then would most likely be cross-connected to the horizontal floor patch panel (blue field). We often see a mixture of cross-connects and interconnects, both in the ER and the TR, and we discussed the advantages and disadvantages of each in Lesson 6. The designer needs to be aware of these options and considerations when making decisions on the deployment of interconnect versus cross-connect.

8: Administration Cord Distances.

TIA-568 recommends a maximum length of 20m for jumpers and patch cords in the MC and IC administration areas. In addition, both ISO and TIA recommend a maximum combined length of 10m at the FD (HC) and Work Area. TIA recommends a maximum of 30m if using cords to connect directly to telecommunications equipment in the main or intermediate cross-connect.

Question:


11: Labeling.

Throughout the course the label colors for administration field labels have been discussed so you should be confident about this aspect of administration. We will now review this look at other aspects of labeling requirements in administration areas.

12: Administration Element Color Coding.

The TIA-606 offers a far more detailed approach to labeling schemes than either ISO/IEC14763 and 11801 (International), and CENELEC EN50174-1, 2 and 3 (European), Both TIA and CENELEC define administration by complexity of project, TIA in terms of 4 classes of administration and CENELEC in terms of 4 levels plus enhanced. The principal behind both are similar, but that's where the similarity ends.
These classes define the level of administration labeling recommended and are defined as:
Class 1 - Single ER;
Class 2 - Multiple Telecommunications Spaces, for example an ER and a number or TRs;
Class 3 - Includes campus (buildings and OSP);
Class 4 - Multiple Sites.

Class 1 defines identifiers for a single TS and horizontal, then Class 2 adds multiple space identifiers, etc. An identifier is associated with each element of the telecommunications infrastructure to be administered. A unique identifier, or a combination of identifiers, is constructed so as to uniquely refer to a particular element, serving as the key to finding a record of information related to that element.

Cabling administration and labeling is an important cabling element that allows for easy maintenance and management of the telecommunications cabling system. If a cabling element contains mixed categories of cabling, such as the horizontal, they should be printed by a mechanical device and identified by enhanced color-coding (i.e., white stripes on blue label to differentiate higher performance cabling) or suitable markings. Cables, as a minimum requirement, should also be identified at both ends with labels suitable for wrapping. The labels should consider size, color, and contrast and be made of a durable material, such as vinyl. A white printing surface should be used allowing the label to wrap around the cable so that the clear label end self-laminates the printed area. Labelling of cables and components in a system should be resistant to the environmental conditions at the point of installation and equal to the life of the component being labeled. Always refer to your country's specific standards.

13: Administration Element Color Coding.

The labels for the ER to TR which is a primary backbone (Level 1) will be white, while the TR to TR or ER to ER is secondary (Level 2) cable and will be gray. All equipment outlets are purple. An example of a yellow field is a BAS Horizontal Connection Point (HCP). TIA and CENELEC recommend the following areas be included in the labeling process: Horizontal pathways and cabling; Backbone pathways and cabling; Telecommunications grounding and bonding; Spaces (EF, TR, ER); Fire-stopping.

14: Administration Labeling Examples.

Let's take an example of a label designation using the TIA-606 standard. 2B-A01 (fs-ann). 2B equals 'f', the level and 's' the space. 'A' equals 'a' the panel or group of panels, and '01' 'nn' the port. Note 'a' can be either a panel ID, as in this example, or a group of panels. So, it could identify the rack. 'nn' can be between 2 and 4 digits, to represent the panel port. So, if you used 'a' as a rack identifier, then you may use the nnnn to identify a sequential numeric group of ports through all of the panels in the rack. Alternatively, you could use the first 'n' as the panel ID.

There are many combinations. The 2B on the rack may be expanded to add the building ID on the campus for Class 3 administration and site in a Class 4 administration. TIA-606 is a good reference but the customer and or consultant may well require input into this area of the design.

15: Grounding Administration.

This is an example of the TIA-607 grounding notation, with labeling as per the TIA-606 administration standard. Follow your local regional or national grounding codes.

16: Labeling.

Just before starting on modular panels, one of the resources that can be found in the my CommScope part of the website is labelling templates. In here, there are templates that allow you to generate labels for CommScope panels and outlets as required using Microsoft Excel or Word with the correct spacing between them. By either printing on plain paper or using standard off the shelf pre-punched Avery labels, the correct part number for the labels is specified against each panel. These can be printed in the office and supplied to the engineers as required as part of the recording and testing regime.

17: Labeling.

Included in the Labeling Solutions are electronic templates. CommScope has collaborated with DYMO, providing pre-formatted electronic templates to make the labeling of structured cabling systems easier and more efficient for installers. These templates can be downloaded free of charge and imported into RHINO CONNECT software. Label information can then be entered into the template either manually or directly from a Windows-based PC application, then printed on labels to specifically fit CommScope structured cabling components.

18: Cabling Documentation.

Labeling records are developed from the elements of the telecommunications system using information that may link together to form a circuit from end-to-end. Once compiled, often in spreadsheet format, this circuit information may be used to generate reports, work orders, and drawings. The linkages between the identifiers and records are used to create the circuit information. This level of administration is usually performed by the customer or system administrator. The TIA-606 standard provides examples of these records. Recording of static circuit records in spreadsheets and detailed plans can be realistically achieved without the use of a database. However, size, complexity, and frequency of changes may quickly challenge this method of recording. It is important these records stay up to date not only for you but also the customer.

19: That Completes This Lesson.

Welcome to Administration Area Design - Copper Administration Fields.

2: Modular Jack.

It's important to remember that the standards only specify using the modular jack (RJ45) style at the TO (Telecommunications Outlet). The administration areas in the ER or TR where patching is performed may be modular jack, a high density 110 style or may be a proprietary patching solution, providing it performs to the category interface performance set out in the standards for administrative hardware.
This variation in signaling applications means there is a large variety of administration solutions from different vendors available, but we will focus mostly on modular jack administration panels. The designer will need to fully understand though any other proprietary panel solution, should they be considered.

3: Modular Jack.

Most modular jack apparatus passes all four pairs through, whether or not the applications use all of them. When designing copper voice fields though, digital phones usually only require one pair per port. Here there is a multi-pair primary backbone cable running from the PBX in the ER, to the white field in the TR. The white field uses two 48-port modular panels, providing 96 voice ports which can be served by a 100-pair cable. This panel shows the blue pair position on each port terminated with a pair, in color sequence order, from the 100 pair cable. The design concern here is that we are committed to sizing the backbone for voice support using the minimum of one pair and the blue pair position. This restricts using other phones that might use two pairs or even other pairs, apart from the blue ones. That flexibility could be improved by doubling the backbone size to 200 pairs but that still leaves the decision on which other pair to wire. Fortunately VoIP (Voice over IP) handsets are becoming more common, which share copper data cabling to the desk and have fiber backbones connecting Ethernet switches.

4: Copper Administration Fields.

Now that you understand the copper panel wiring implications for at least modular jack panels, let's take a general look at planning copper administration fields.

5: Which Administration Solution?

Selecting an administration solution will require you to take into account the applications and administration environments. This example shows two distinct areas. Example Area 1 features: Exclusively voice wiring; Patching may be done with simple 1 or 2-pair cords, or jumper wires; It is low-performance; Patching may be semi-permanent; and patch fields are typically less administration friendly and are often completed by technicians and may require punch down tools. Proprietary voice style flat block systems would be most suitable and certainly cost-effective for this area rather than modular jack.

Example Area 2 features: A mix of voice and data applications; Active hardware interfaces with modular jacks; Possibly, non-technical administration staff completing patching and the avoidance of tools; High-performance applications. You may consider a different patch solution for this area of the infrastructure. The customer or the RFQ specification is likely to express a preference for the style of administration to be used, with the performance of applications and anticipated longevity of the design dictating the performance level of the solution. Within Area 2, it is not uncommon to find more than one administration solution, one type for data and another for voice and BAS. So, as a designer, keep an open mind!

6: Determine the Circuits Termination & Sizing.

Here is a simple example of the design you may get to, showing which circuits, in this case copper and fiber, terminate in each administration area. The backbone sizing shown here is determined using either the RFQ specification you were given at the offset or from the consultant or customer's network design team's input. In the absence of these, calculations can be based upon the minimum sizing for work areas and backbones as covered in earlier lessons. You can see from the graphic it's now really easy to picture the administration to be included in each ER or TR. Depending upon the administration solution chosen you can work at 'pair' or 'modular jack' level, to size the administration field requirement. For example in the ER, and assuming we are designing using a cross-connect, there are 84 work areas, with 4 TO's at each, making a total of 336 cables (jack field). We also have campus cabling connecting to another building, one 24 core fiber for data and 900 copper pairs providing voice from the PBX which is situated on the same floor as the ER but is connected via some copper tie cable. And so the calculations will go on, compiling a list of all the termination equipment required for the project.

Question:



9: Copper Field Planning Considerations.

This type of situation here we need to avoid by good design practices for the equipment and telecommunications room administration fields. Now that we have calculated the number of panels required, it needs to be checked for 'patchability' then re-order the plan if required for optimization. Remember to allow for cable management, unless side management is available and also for the growth of certain wall fields. Finally, assemble a parts list and produce a graphic layout for the installation teams.

10: Planning Field Orientation & Cable Management.

The way you allocate different fields in wall, rack, or cabinet, voice style or modular jack, will have a major impact on how much and where you place cable management. Because each administration solution addresses cable management in a different way, it is important for the designer to consider this aspect very carefully. It can be said that "You cannot have too much cable management - only too little". If you do not design it in, you are likely to have administration issues that are very difficult to correct in retrospect.

This simple example has three common fields, white backbone (voice), blue horizontal, and purple equipment (data). In design 1, the fields have been positioned vertically. Therefore, patching will be forced horizontally, requiring the design to maximize horizontal cable management capacity. This suits a solution that incorporates horizontal cable management. In this design, 2, the fields are positioned horizontally. Therefore, patching will be forced vertically and would suit a solution that always has vertical cable management incorporated, such as additional space each side of the cabinet. The choice of cabinet can provide additional cable management down either side or across top and bottom. In addition, vendors often have options such as angled jack panels that split cables either side into vertical management more efficiently than flat panels. The designer should always quantify the cable management required, taking into account different cord diameters that will vary according to the category of the cable and also the fact that maybe not all positions will be patched.

11: Patching Efficiency.

Consider field layouts to optimize administration efficiency as a good layout can reduce Time To Patch (TTP), improve accuracy, and reduce patch cord cost and weight. Here are two designs for the same scenario of an ER wall field. The PBX is in another room, and connected to the ER by a tie cable, terminated on a gray field. Backbone cabling (white) runs up the riser to the TRs. The ER also serves this floor's TOs (blue) and has some data network equipment ports (purple) that need to be cross-connected to TOs. A campus cable (brown) emerges from a duct and is terminated, via an electrical protection panel, to the brown field. Pairs in the campus cable need to be cross-connected to the gray field.

For this design the following connections are required: Network to horizontal (purple to blue); PBX to horizontal (gray to blue); PBX to the other building (gray to brown); PBX to the TRs via the backbone (gray to white).

The top design is a poor attempt at a wall layout. It only shows one connection from the blue field to each of the other fields, and already it's a mess! Patch cords are long and run across intermediate fields.

The lower design has had some thought put into it. If you have a 'popular field', in this case the gray field, it's a good idea to split it into the two fields. The brown field has been kept to the outside, so it can more easily be cabled to the protectors. The brown field can now easily access the adjacent gray field, which is its only cross-connect target. The white field supports voice to the TRs and can now easily access the gray field on either side. The blue field can now easily access the gray field and the purple field. So, all fields to be cross-connected are adjacent. You will not always get a perfect result like this, where all fields are adjacent and there can also be more than one suitable alternative. The customer/consultant should definitely be involved in the signing-off on all aspects of the final layouts, but it is your responsibility as the designer, to use your experience to offer alternative layouts.

12: Planning Growth.

Certain fields will tend to grow, no matter how much planning you do, but if calculated correctly at the offset and sized to the maximum capacity of the PBX the primary backbones such as campus (brown) and primary building backbone (white) will not need to change. Some fields though, such as the purple field terminating data network ports will inevitably grow, and the blue field will possibly be added to. Budget constraints and unforeseen circumstances may require other fields to grow following installation so the designer should take this into account. Another consideration is where to leave room for the growth, as administration systems are installed differently. For example, some panel systems are terminated from the bottom-up, even though the numbering scheme will usually start at the top-left of the field and go down, while access to some modular jack systems can also be difficult, retrospectively. Discussing these options with the client always helps.

13: That Completes This Lesson.

Welcome to imVision Hardware and Installation - iPatch Hardware.

2: iPatch Hardware.

There are three major aspects of the CommScope AIM solution: iPatch intelligent panels, the imVision Controller X, and the imVision System Manager software. To cover these areas, this lesson is divided into three parts. In this part we will overview the iPatch hardware.

3: Why Intelligent Patching?

Let's take a look at why an Intelligent Infrastructure solution might bring huge benefits to today's fast-changing networks. It has become evident that a passive network infrastructure can be a blind spot in a network. Effective configuration management cannot rely on manual documentation or be affected by potential mismatches in labeling that can result from outdated information. Critical incident management processes may be seriously hampered by undetected changes at the physical layer, missing port information, or unattended critical connectivity events. Change management becomes a flying-blind exercise when relying on paper work orders, unguided moves and changes, and unknown connectivity paths, requiring labor-intensive deployments and manual updating of applications.

4: Why Intelligent Patching?

By deploying an Intelligent Infrastructure, customers can gain the vision, knowledge and control they need to optimize critical processes and prevent unnecessary degradation of performance or downtime.

With an Intelligent Infrastructure, configuration management can rely on automated connectivity documentation, including networked device discovery and location mapping, as well as real-time reports showing up to the minute configuration information.

Incident management is greatly enhanced with real time detection of physical layer changes, monitoring of switch port status, event notification, and integration with external devices such as cameras or environmental monitors. And change management can be made into a controlled and automated process that relies on electronic work orders to provide advanced guidance to the technician, while removing the need for the IT administrators to get involved with the cabling management details due to the use of intelligent service provisioning and server deployment algorithms.
Integration with external applications allows for closed-loop incident management and change management processes that increase the efficiency and productivity of the entire organization, while audit trails improve accountability. So, Vision + Knowledge = Control.

5: AIM Standard ISO/IEC 18598 & ANSI/TIA-5048.

imVision is an Automated Infrastructure Management solution known by the acronym AIM. This solution meets the requirement of the recently published standards ISO/IEC 18598 and ANSI/TIA-5048. It is a combination of hardware and software working together to bring automation to the infrastructure management.

6: AIM Standard ISO/IEC 18598 & ANSI/TIA-5048.

imVision, an AIM solution, has three main objectives. The first one is to detect the insertion or removal of a standard patch cord. This action allows the system to detect in real time when the infrastructure system has changed. The second one is to document these changes to the infrastructure. For example, when a patch cord is added the system, it will complete the connectivity trace to the circuit that has been created, including the end device outlet, the patch panel port, the switch port and the service associated to the last connected patch cord. Finally the third objective is to offer the possibility to communicate easily with other software tools, that can be added to the infrastructure documentation in a standardized way.

7: AIM Standard ISO/IEC 18598 & ANSI/TIA-5048.

This solution is based on three distinct parts. Functional requirements which describe how the solution should work rather than merely the specifications of its components. A series of benefits which an infrastructure should recognize when an AIM solution is installed. These will include intrinsic ones including cabling documentation updated in real time, improvement change management, incident management and asset management. Extrinsic benefits relate to linking in of information from other tools such as NMS, IP telephony, security cameras, BMS and energy management. The Data Exchange Framework or API links this information to the infrastructure documentation.

8: AIM Standard ISO/IEC 18598 & ANSI/TIA-5048.

The five key features of imVision are: Detection of patch cord insertion/removal, documenting the cabling infrastructure, discovery of network equipment and end devices, location information for network connected devices and generation of real time events.

9: SYSTIMAX 360 iPatch Architecture.

Let's look at this configuration of architecture, where we have a single rack with one imVision Controller X and multiple iPatch panels. Each panel and the controller is linked to a panel bus which is mounted on the side or the back of the rack, allowing them to communicate with each other. imVision Controllers learn all the patching adds, moves, and changes involving the iPatch ports on its rack, and is linked to the next controller in the next rack using a standard patch cord. In a row of racks the first controller in the chain is connected to the LAN to access the server and the imVision System Manager software. This configuration applies for the imVision Controller X introduced in 2018, the legacy imVision Controller introduced in 2012 and the original Rack Manager Plus and 360 Panel Manager.

10: imVision Architecture: Multi Rack.

The imVision Controller X includes an exclusive new feature that allows it to control a maximum of 3 racks with 10 rack units of iPatch hardware in each, either copper or fiber. Previous versions of the imVision controller were unable to do this, so this feature provides more flexibility.

11: SYSTIMAX iPatch Panel Intelligence.

iPatch panels are the heart of the imVision solution. Each iPatch enabled copper or fiber port has an infrared sensor that monitors the insertion or extraction of a patch cord. When the panel detects a patch cord being added or removed, it records that change of connection locally in the firmware. Tracing a cord connection is simply achieved by pressing the button associated to the port. An LED adjacent to this button indicates where the connection is made, even across racks, and in addition, the imVision controller displays the connectivity details. Panels achieve this by communicating additions and removals of patch cords to the controller in their rack.
This information is also communicated to other controllers locally connected in a row of racks, and to the System Manager software. It is important to emphasize that iPatch panels work with standard patch cords, unlike many other solutions. It is also important to understand that the 'patching intelligence' is external to the communications path, i.e. the copper or fiber channel between say a PC and a switch.

12: SYSTIMAX 360 iPatch 1100 Copper Panel.

First, let's take a look at the SYSTIMAX 360 iPatch 1100 copper panels. These panels are available to order in two versions. Standard version is iPatch-ready which means they can be upgraded at a later date if required or iPatch-enabled that are supplied with the iPatch sensors built-in. Evolve panels come in two sizes, 24-port 1U or 48-port 2U, straight or angled and in either GigaSPEED GS3 XL or GS6 X10D rated versions. Being 360 panels they have the improved cable management retainers at the rear. The 24-port version comes with one panel bus jumper cable to connect to the panel bus while the 48-port version has two.

13: SYSTIMAX 360 iPatch PATCHMAX Copper Panel

Another version of the copper iPatch panels is the PATCHMAX. Again like the 1100 panels the PATCHMAX panels come in both 24 and 48 port versions, are available for XL and X10D and take up the same amount of space on the rack. In addition to the standard 1100 panels they have built in cord management at the front. When using standard racks or cabinets without additional side management this can be quite beneficial. The PATCHMAX range also has an innovative termination solution, that the modules can be reversed allowing termination from the front if required.

14: SYSTIMAX 360 iPatch F/UTP Panel Series.

This SYSTIMAX 360 GigaSPEED Evolve Modular F/UTP panel is designed to accommodate the High Density HGS620 FTP connectors. Again it has the same rack space requirements and options as the previous panels we have seen.

15: M4200i 24 Port iPatch Modular Panel.

So far all the iPatch panels we have seen are based on the 1100 panel. The SYSTIMAX 360 Evolve modular panel that is available in 24 or 48 way is unable to be upgraded to an iPatch enabled version so if an iPatch modular panel solution is required, then the M4200i 24 port panel should be used. This is available as iPatch enabled only.

16: SYSTIMAX 360G2 iPatch Fiber Shelf.

Next, let's look at the SYSTIMAX 360 iPatch-enabled G2 1U fiber shelf. Ordered as a 360-iP-G2 it comes in two versions: fixed (FX) and sliding (SD), and includes 4 LC cassettes, for a total of 24 duplex LC intelligent ports. Please note that when ordering or identifying this panel, the lower case iP in the code stands for iPatch, and not upper case IP which is InstaPATCH. Also, the overall panel code configuration for the two panels is slightly different. One panel bus jumper is included, as this shelf only requires one connection to the panel bus.

17: 360G2 iPatch 96F-LC Sliding Shelf.

This is the 360 G2 iPatch 1U 96F fiber shelf fitted with 48 duplex LC ports either by direct termination or splicing. It can also be ordered with 4 distribution modules (fiber cassettes), MPO to LC, available in LazrSPEED or TeraSPEED versions. There is also a 2U version, 192 fiber, of this shelf if a higher capacity is required. Two iPatch ready kits are fitted to the front of the 1U 96F shelf or four if using the 2U 192F version.

18: Port Numbering, Kits & Modules.

Each iPatch ready kit provides intelligence to two modules per shelf and connects to a backplane kit inside the shelf using a small ribbon cable. One kit serves modules 1A and 1B on the left side and the other serves modules 1C and 1D on the right. If using the 2U shelf then the other 2 ports would be used to serve '2A and 2B' and '2C and 2D'. Note that the port numbering in these shelves is done on a per fiber module basis. This means that numbering goes from 1 through 6 in the bottom row and from 7 through 12 in the top row in EACH fiber module.

19: Backplane Kit Ports & Connections.

The backplane kit mentioned earlier, is a new component fitted in some G2 fiber shelves. Sometimes it is called "the sharkfin". It can connect up to four iPatch ready kits and has a single port for the jumper cable back to the panel bus. The iPatch ready kits must be connected to the corresponding backplane ports, as shown here in the graphic. There is an additional connector shown here for an LED kit cable connector, but this is only used for the UHD (Ultra High Density) shelves.

20: 360G2 iPatch - MPO Sliding Shelf.

The G2 MPO fiber shelf is available in 1U and 2U versions. The 1U has 4 MPO fiber modules, each with 8 MPO through ports presenting a total of 32 MPO ports in the shelf. Each MPO passes 12 fibers making a total of 384 fibers in 1U. The 2U is double the density, so with its 8 MPO fiber modules gives a port count of 64 MPOs making a total of 768 fibers. Again the panels use the iPatch ready kits and the same numbering/connectivity rules apply.

21: Port Numbering, Kits & Modules.

Note how the port numbering runs on these MPO shelves: each fiber module is numbered from 1 through 4 on the bottom row and from 5 to 8 on the top row. In the case of a 2U shelf, the same numbering repeats on each of the two rows. The top row is called Row 1, the bottom row is called Row 2.

22: 360G2 iPatch - UHD InstaPATCH Shelf.

The G2 iPatch LC UHD, Ultra High Density, InstaPATCH shelves are available in two versions. The 1U shelf includes one sliding tray that accommodates four distribution modules while the 2U shelf has three sliding trays to make a total of twelve distribution modules. This product is intended for indoor use or can be used outdoors in a suitable protective enclosure. Each tray comes with four InstaPATCH fiber modules presenting a total of 48 duplex LC ports and are available in either LazrSPEED or TeraSPEED, and also two iPatch ready kits to provide the intelligence. As discussed earlier there is an additional port on the backplane kit that is used for this particular range of panels for a front LED.

23: 360G2 iPatch 2U 288-LC UHD Shelf.

This is the 2U version of the G2 UHD iPatch LC shelf. It is also known as the 2U 3-row shelf, as it has 3 rows or trays in 2 rack units of space, making it Ultra High Density giving up to a total of 144 LC duplex ports in the whole shelf. These shelves come with one backplane kit per tray, and connections to the iPatch kits and front LED are identical to those for the single-row shelf. This shelf will require 3 connections to the panel bus, one per tray or backplane kit.

24: 360G2 iPatch MPO UHD Shelf.

The UHD shelves also offer an MPO panel variant. The 1U 32 MPO and the 2U 3 row 96 MPO UHD shelves. These are the MPO to MPO through coupler versions. The 2U version can handle an impressive 1,152 fibers.

25: Front LED Kit (UHD Shelves Only).

Here, we have a better view of the Front LED kit. It allows technicians to easily see when the LED for a particular UHD tray is ON even with the high density of jumper cords that these trays allow. The LED kit replaces the central cable manager and is cabled through to the backplane kit.

26: SYSTIMAX HD Fiber Shelf.

In addition to iPatch 360 and UHD shelves discussed, iPatch versions of the newer CommScope HD and UD shelves are also available. They are available in 3 different sizes and various combinations of outlets. Full details can be found on the CommScope website.

27: 360G2 iPatch HD Fiber Shelf.

The SYSTIMAX 360 iPatch-enabled G2 High Density (HD) fiber shelf was discontinued on December 2017, however the fiber modules are still in production for currently installed systems. This shelf supports up to three iPatch G2 High Density pre-terminated InstaPATCH Plus modules in LazrSPEED, TeraSPEED or OptiSPEED options, providing a total of 72 duplex LC ports (144 fibers) in a 2 rack unit footprint.

28: Installing the Modules.

The high density iPatch fiber modules must be oriented for the proper InstaPATCH polarity. Identical modules are used at each end of a trunk cable, but one module must be in the ALPHA orientation and the other module must be in the BETA orientation. If this is not done correctly, port 1 will go to port 24. Whenever supervising installation ensure that the polarity is checked from end to end using a tracing device such as a VFL (Visual Fault Locator).

29: SYSTIMAX imVision Controller X.

The second component of the imVision solution is the imVision Controller X. It is an improved version of the legacy imVision Controller, with a bigger and brighter screen, delivering more power and having louder notifications. The unit itself takes up only 1U and has a large 5 inch color touch LCD display that can be moved up or down and tilted for easy use. The display also has back lighting, which activates when any button is pressed on a panel, that is connected to the controller. The imVision Controller X supports up to 45 Rack Units of iPatch copper panels or 24-port fiber shelves and it supports up to 52 rows per rack when only iPatch 96 fibers or iPatch 32 MPO overlays are used. For a mixed environment there is an imVision Power Calculator that can be used to ensure there is sufficient capacity.

30: SYSTIMAX imVision Controller X.

Included with the imVision Rack Controller is a power supply with interchangeable AC plugs, a 7 foot patch cord for connecting to an adjacent rack controller, rack mounting screws and the folded full rack panel bus.

31: imVision Controller X Rack Extender Kit.

If using the Controller X for a multi-rack configuration, a rack extender kit will be required, and this comes with two additional panel buses and two 13ft panel bus jumpers.

32: SYSTIMAX imVision System Manager Software.

The third component is the imVision System Manager software. It is an easy to use Windows-based program that allows you to build a complete database of your network including all cabling components, switches, servers, computers, etc. and their patching status. Users can manage, monitor, and control infrastructure connectivity from their desk via an intuitive interface. This course does not cover the imVision System Manager software but for training on this, please see the GL5555 Certified imVision Support Specialist course.

33: That Completes This Lesson.

Welcome to imVision Hardware and Installation - Assembly. In this part of the lesson, we will focus on the assembly of the iPatch hardware components.

2: imVision Installation Tasks.

To install an imVision system, you must complete the following tasks in the order described:
A. Install the panel bus;
B. Install the Rack Controller;
C. Connect Rack Controller and RM LAN;
D. Install iPatch panels;
E. Power up and setup;
F. Install the other equipment in the racks;
G. Cable iPatch panels and other equipment;
H. Connect first Rack Controller to the LAN;
I. Configure the network settings.

3: Task A: Install Panel Bus

The first step, task A, is to mount the panel bus in the rack or cabinet. The panel bus allows communication and provides power between the Rack Manager and all the panels in the rack. Ensure that the racks chosen will suit the positioning of the panel bus and that the surface is free of protrusions such as threaded inserts and is not in a position where it may be accidentally fouled once the rack is fully terminated with cables. Unfold the panel bus, which is shipped folded in sections, and make sure it is oriented correctly with the notch on the top of the first connector and the lowest section with the 'BOTTOM RAIL' label on it, so is logically at the bottom of the rack or the cabinet. Align the top connector in-line with the top panel or near the top of the area requiring panel connections and then one section at a time, remove the adhesive backing and press the panel bus firmly into place.

4: Task B: Install the Rack Controller.

In the Rack Extender kit we mentioned in the last lesson, the two long panel buses are ribbon cables inside black tubing and these should be carefully routed in order to connect the additional two panel buses and the imVision Controller X. Ensure they are secured to the rack or cable management where possible to avoid accidental damage.

5: Install the Rack Controller.

Task B is to mount the Rack Controller. It is recommended to use the 34th 1U slot up from the bottom of the rack so that the top of the unit is about 65 inch (1.7m) above the floor.

6: Connect to the Panel Bus.

Connect the panel bus jumper to the nearest panel bus socket. All jumper cables connecting to the panel bus now come with a spare socket attached, so this needs to be fitted to the bus housing by turning it at an angle and then turning it back to lock it perpendicular to the frame. Ensure the panel bus jumper is inserted in the two adhesive clips provided on the bottom of the controller. Unfold pre-connected USB cable from under controller and plug the connector into the DISPLAY port on the rear of the controller.

7: Task C: Connect the Controller & LAN.

Here we can see the ports at the rear of the imVision Controller X. Going from left to right, there are two power ports which like the earlier versions of the controllers allow dual power supplies to be fitted for redundancy purposes. With the controller only one power supply is included, but a second can be purchased if required. In this arrangement, both supplies are active and share the load the controller requires but if one supply goes down, the other one immediately takes the full load without interruption to the service.
Next there are three panel bus connections. The middle port is used for the rack the controller is in and then the outside two are used where multi-rack configurations are required. If there was only one additional rack, only two ports would be used. After these there are two RJ45 ports labeled A/IN and B/Out, used to interconnect controllers. Next two USB ports, one for the display and the second as a spare. Finally, at the end is the built-in Gigabit Ethernet port and through this the imVision Controller X can provide the Network Manager functions.

8: Connecting Multiple Controllers.

When connecting multiple controllers used in single rack configuration, the 'OUT' port in the first controller should connect to the 'IN' of the second using a standard patch cord and then continue on with same methodology. The last controller in the chain should only have the "IN" port connected. If connecting earlier versions of imVision Controllers, to the latest imVision Controller X, ensure that the push button switches on those models are configured accordingly.

9: Connecting Multiple Controllers.

When connecting multiple imVision controller X's in multi-rack configurations they can be connected in the same zone when those controllers are configured in "Multi Rack" fashion, using the RJ45 In and Out ports as shown here.

10: Task D: Install the iPatch Panels.

Task D is to install the iPatch panels on the rack and connect the jumper cables provided with each panel to the nearest panel bus socket. There is a limitation in the amount of power a controller can supply to the panels at the rack. Because of this CommScope has developed a simple calculator tool that allows you to confirm your design does not exceed the power limit, based on the number and type of panels you are planning in a single rack. In some circumstances, up to 52 rows per rack per cabinet can be supported. Always use the calculator to be sure.
Additionally, if an imVision Controller X is configured in a 'multi rack' mode, its own rack and the two dependent racks can only support 10 Rack Units of iPatch panels each. There is also a limit in the number of iPatch panels that can be connected to a single panel bus port. The limit is 5. Start a new chain using a new panel bus port for the sixth panel you must connect to the panel bus. For detailed instructions, refer to the installation instructions provided with each panel. Make sure that each iPatch panel is securely connected to the panel bus as this is one of the most common installation problems.

13: Task E: Power Up & Setup.

Connect the power adapter plug to the PWR1 jack on the back of the imVision Controller and route the power adapter cord along the display patch cord. Use the strain relief strap to secure the power adapter cord to the display patch cord. The Controller takes about three minutes to initialize and will display a red light on one side at this time. When ready it will ask you to program the order of the equipment in the rack.

14: Ordering Panels & Modules.

To program the order of the panels in the rack, start from the top and moving downwards push any port button in each panel. If you have a G2 HD shelf, push one button in each module, starting from the left and moving to the right. If the panel is a 48 port copper panel, push one button in each of the two rows. If at any point the process becomes disrupted or if an error is made in the sequence, the process can be repeated from the beginning by choosing "Start Over" on the controller's touch screen.

15: Ordering Panels & Modules.

Once you have pushed a button on the last panel, the screen should automatically change to the Ready status shown here (sometimes also called Idle screen). The hardware is now ready. The iPatch Zone is ready to detect patching activities and keep them recorded in the local memory in the controllers. The installation is ready to be cabled and handed over to an imVision Specialist for commissioning.

16: Task F: Install Other Equipment in the Rack.

Once you have finished ordering the iPatch panels, the next is task F, where you install other non-iPatch equipment, like generic panels, network equipment, patch cord organizers, etc, in the rack. When doing this, follow each vendor's instructions.

17: Task G: Cable the iPatch Panels & Other Equipment.

Task G: At this point, you are ready to terminate all cabling to the back of your panels. To make it easier to terminate the cabling, you may disconnect the power adapter plug from the POWER jack on the back of the imVision Controller. When you have finished cabling the equipment, be sure to connect the power plug again and route the power adapter cord through the strain relief. Also, try not to do any patching activities in iPatch panels while the power is off. For instructions on how to terminate cables on the iPatch panels, refer to the appropriate SYSTIMAX installation course.

18: Task H & I: Setting up the Network Connections.

Task H. Finish connecting the selected imVision Controller, and Task I configuring the network settings is the responsibility of the imVision trained specialist, who has taken the GL5555 Certified imVision Support Specialist course. Once you have successfully completed all tasks you can begin using your imVision system. It is extremely important that you follow the imVision rules when doing patching that involves iPatch ports.

19: Summary.

In summary, the most important points to remember are: Carefully follow installation instructions and sequence; Should you need to replace an iPatch panel or imVision Controller contact your imVision support specialist who is trained in the GL5555 Certified imVision Support Specialist course; Follow imVision patching rules.

20: That Completes This Lesson.

Welcome to imVision Hardware and Installation - Upgrades. In this part, we will look at upgrading iPatch ready panels and shelves to iPatch enabled.

2: SYSTIMAX 360 iPatch Panel Upgrade Kits.

All panels and shelves in the SYSTIMAX 360 range with the exception of the copper modular shelf are supplied standard as iPatch ready, which means they can be upgraded at a later date if required. We discussed the iPatch enabled M4200i modular panel earlier in this lesson that can be used if a modular option is required. There are three different copper iPatch upgrade kits available for the 1100 Evolve or PATCHMAX panels. See the CommScope eCatalog for full details.

3: SYSTIMAX 360 Copper iPatch Upgrade.

The copper iPatch upgrade kits come in different pack quantities. 24 port kits for the flat or angled 1100 panels, PATCHMAX are packed in tens while the 48 port versions are in fives. The upgrade strips are similar to the one shown here and are straightforward to install with a single jumper ribbon cable that needs to connect between this and the panel bus.

4: SYSTIMAX 360 Copper iPatch Upgrade.

The first step is to remove and discard the labels from the front of the modules along the panel row, using a spudger, a small screwdriver or a knife blade. Remember you will need to re-label the modules when you have finished.

5: SYSTIMAX 360 Copper iPatch Upgrade.

The panel is now ready for the upgrade kit to be mounted. As the panel will probably be fully terminated it may help at this point to unscrew it and pull it forward about 50mm (2 inch) away from the rack or frame. Take the jumper cable that comes with the kit and identify the end with the connector that connects to the iPatch overlay. From the back of the rack, feed the end of the jumper cable through the rectangular opening of the SYSTIMAX 360 panel, as shown here. This connector is keyed so orient it before feeding it through the hole, to prevent possible damage by twisting it afterwards. Connect the jumper cable to the end of the upgrade kit, then feed some of the cable back through the hole before placing the upgrade kit over the ports and snapping it into place by sliding it to the left.

6: SYSTIMAX 360 Copper iPatch Upgrade.

At the end of the panel, a ribbon cable retainer needs to be fitted so you will find it easier to put the retainer on the cable and push it into position before removing the adhesive protection tape on the back of the retainer clip. Route the rest of the panel bus jumper cable and put a second clip on it to ensure it won't get fouled when screwing the panel back up to the frame. Confirm the bus cable is still connected at the front on the panel and replace the decorative bezel before plugging the jumper cable into the panel bus. This completes the upgrade procedure.

7: SYSTIMAX 360 iPatch Fiber Upgrade Kits.

There are five different upgrade kits available for fiber shelves. Again see the CommScope eCatalog for details. The 360 fiber shelf shown here, like the copper version, is easy to upgrade even when the fiber shelf is in use as the overlay kit is specially designed to allow this 'in use' fitment. The kit contains everything apart from a T10 Torx screwdriver that will be required to secure the overlay to the front of the shelf.

8: Fiber Cassette Style.

Before starting the process, check the style of fiber cassettes fitted to the shelf. The first generation of cassettes or couplers with the long edges are not compatible as the iPatch overlay will not fit. Also if using later InstaPATCH cassettes that are fitted with internal shutters, the same will apply. Providing neither of these cassettes or couplers are fitted, the upgrade can continue.

9: 360 iPatch Ready Upgrade - Fiber.

Pull out the shelf if sliding, which will make the task easier. If it is a fixed shelf it may need to be loosened in the rack to help with access. Remove the smoked Perspex protection door and the plastic shelf cover.

10: 360 iPatch Ready Upgrade - Fiber.

Quite often forgotten is the re-labelling of the overlay until the panel is upgraded and it's very difficult at that point, especially if fully patched with cords. If it is done at this stage, it will be so much easier. The kit comes with replacement labels that are colored to match the fiber type in use in the shelf, so these can be used if required.

11: 360 iPatch Ready Upgrade - Fiber.

Remove the hinged dust covers from the cassettes and also the plastic frame surrounds if InstaPATCH modules are fitted. Note, the hinged covers cannot be refitted once the iPatch overlays are in place so these can be replaced with plastic bungs if available.

12: 360 iPatch Ready Upgrade - Fiber.

The instruction sheet that is packed with the shelf gives step by step details and there is also video available in the download area of this lesson explaining the process. Included with the overlay kit is a long ribbon cable, corrugated tube, tube clips and also ribbon retainer clips to ensure the cable is protected along its entire route. Note, on this overlay unlike the copper one, the ribbon cable connects to the middle of the overlay.

13: 360G2 96F & MPO Upgrade Kits.

We have also mentioned that iPatch upgrade kits are available for both G2 96 F or MPO shelves and G2 UHD 96 F and MPO iPatch ready versions of the shelves. The two kits are almost identical, but the UHD kit includes extra components: front LED kit and plastic caps to number trays front and rear. The G2 upgrade kits include a total of 10 iPatch kits and all cables and components to update 5 rows to iPatch while the G2 UHD upgrade kits include 12 iPatch kits to upgrade 6 UHD trays to iPatch.

14: iPatch Panel Installation & Upgrade Support.

In summary, installing the latest shelves is similar in principle to the existing series of panels, but a few new elements like backplane kit or front LED kit are present. The final step is to power up the rack and program the order of panels. To complete this lesson, please review the installation videos and other PDF documents, including the 'Program Order of Panels', available in the lesson download area. Remember that imVision installations require specialist knowledge of the firmware and software, and your imVision-trained specialist should be involved in such projects.

15: That Completes This Lesson.

Welcome to Safety, Inspection and Testing - Fiber Testing, where will cover the SYSTIMAX requirements for testing both single and multi fiber installations

2: Fiber Testing - Standards.

Accurate characterization and testing of installed optical fiber cabling is crucial to ensuring overall network integrity and performance. An optical fiber cabling link may consist of a fiber or concatenated fibers (spliced, cross-connected or interconnected) with a connector or adapter on each end. The fiber type, link length, the number and quality of terminations and splices, cable stresses, and wavelength can all affect attenuation measurements.
As we have seen in the inspection section, link attenuation can be negatively influenced by severe cable bends, poorly installed connectors or even the presence of dirt on the end-face of connectors. Attenuation measurement results should always be less than the designed attenuation budget (also known as loss budget) that is based on the number of terminations and cable length. Documenting the test results provides the information that demonstrates the acceptability of the cabling system or support of specific networking technologies. Fiber system testing with regard to infrastructure installations is covered predominantly by the IEC 61280-4, TIA-526 and CENELEC EN50346 standards, and these standards are referenced from many other documents such as the ISO/IEC 14763-3. The TIA-568.3 cabling standard also covers the fiber optic testing in some detail but it defers to TIA-526 part 7 which covers Optical Power Loss measurements of installed Single-mode Fiber cable plant and TIA-526-14C Optical Power Loss measurements of installed Multimode Fiber cable plant. TIA-455 covers measurement methods and test procedures for attenuation.
There are several standards bodies globally, and often these standards have country-specific variants. There are also vendor-specific requirements that may apply regionally or globally. In some cases, end-face inspection and launch conditions for multi-mode fiber may have different requirements. It is also important to note that ALL standards are living and evolving documents with standards bodies meeting several times per year. Since this course is aimed at a global audience, it is impossible to address each specific regional, country, or vendor requirement.
As an example specific to Tier 1 testing, there are regional differences related to reference methods and the allowable loss per connection. For the most part, the examples in this course will follow the TIA suite of standards. In all cases, refer to regional or vendor-specific standards and guidelines. Regardless of where you are, this course will help you ask the right questions in your region or to the vendor of your fiber.

3: CommScope Field Testing Guidelines.

The latest SYSTIMAX Field Testing Guidelines are dated May 2016 and include the testing requirements of fiber installations for warranty purposes. It is an easy to read document with graphics showing test equipment set up, sections on general testing guidelines, loss calculations, testing procedures, TIA and ISO/IEC standards, and much more. You will find this in the download area of this lesson.

4: Recommended Fiber Testing.

Fiber test standards include for two forms of field testing. TIA define these for example as Tier 1 testing, defined as testing installed optical fiber cabling for attenuation with an Optical Loss Test Set (OLTS), and verifying the cabling length and polarity. Tier 2 testing is optional and includes the Tier 1 tests plus the addition of an Optical Time Domain Reflectometer (OTDR) trace. An OTDR trace can be used to characterize the installed fiber link, resulting in an indication of the uniformity of cable attenuation and connector insertion loss.

Testing is defined within the CommScope field test guidelines and its recommendations all correlate with those of the standards and include the following: The minor attenuation differences due to test direction are on par with the accuracy and repeatability of the test method. Therefore, testing in only one direction normally suffices. However, test in both directions if the installation contains fibers of different core sizes. This is to detect inadvertent mixing of fibers with different core sizes, as the loss in one direction will differ from the loss in the other direction by at least 2 dB if different core sizes are connected together (e.g. 50 µm connected to 62.5 µm) when measured using 62.5 µm test jumpers. Horizontal link segments are short enough that attenuation differences caused by wavelength are insignificant. As a result, single wavelength testing is sufficient. Backbone and composite links may be longer, and attenuation may strongly depend on wavelength in such links. Therefore, it is necessary to test at both wavelengths.

5: Check Your Test Set.

Stable reference power levels are critical to the accuracy of subsequent attenuation measurements. Instability may arise from at least two common causes: battery health and mechanical changes at the connection to the source. Ensure the battery is in good operating condition and fully charged in both the source and power meter. Avoid disturbing in any way the connection from the source to the launch cord after the reference measurement.

6: OTLS Testing Preparation.

OLTS equipment is usually available to operate in multiple wavelengths, and both single-mode and multimode, but this will depend upon the unit. Set the source and meter to the correct and same wavelength.
Note 1: Horizontal link segments are short enough that attenuation differences caused by wavelength are insignificant. As a result, single wavelength testing is sufficient. Backbone and composite links may be longer, and attenuation may strongly depend on wavelength in such links. Therefore, it is necessary to test at both wavelengths.
Note 2: The minor attenuation differences due to test direction are on par with the accuracy and repeatability of the test method. Therefore, testing in only one direction normally suffices. However, test in both directions if the installation contains fibers of different core sizes. This is to detect inadvertent mixing of fibers with different core sizes, as the loss in one direction will differ from the loss in the other direction by at least 2 dB if different core sizes are connected together (e.g. 50 µm connected to 62.5 µm) when measured using 62.5 µm test cords. Note 3: Standards only ask for uni-directional Light Source and Power Meter (LSPM) testing, however many customers request bi-directional results. While bi-directional LSPM testing may provide more data, there is a trade-off with the extra time required and the additional opportunity for dirt and dust to be introduced during the testing process. Bi-directional test results are optional; if used, the direction with the higher loss measurement would be used to determine pass/fail for the link.

7: Test Reference Cords with EF Controllers.

OLTS test equipment is supplied with test reference patch cords that have reference grade connectors which the standards define as being less than 0.1dB for multimode and less than 0.2dB for single-mode. This is because many fiber manufacturers are producing low loss fiber optic components and the loss budgets are becoming increasingly smaller. As a result the amount of light from the power source needs to be controlled very accurately to ensure that the results are both accurate and repeatable.
To achieve this, an Encircled Flux controller is integrated into the reference cord that connects to the light source. Prior to these being available, mandrels were used to help reduce the modes, but depending on how they were wrapped, there could be differences in launch conditions between one set of cords and another. The issue for accuracy and consistency of loss results is that launch conditions from an 'overfilled' source will produce more modes than the fiber can carry - the higher order modes will be absorbed by the cladding along the way and measurements using overfilled sources tend to overstate the actual loss. Meanwhile, 'underfilled' sources carry very few modes, and measurements using underfilled sources tend to understate loss. EF controllers work by restricting the number of mode groups launched from the test cord to within EF specifications, ensuring that the resulting measurements are precise and repeatable according to the EF test standards.
Note: Cleaning of test reference cords requires the entire end-face to be clean otherwise dirt or debris from around the core, could be moved onto the core itself. It is recommended that these connectors be wet-cleaned with fiber prep fluid then dry-cleaned using a stick cleaner or lint free wipe.

8: Testing With OLTS.

Setting up the tester with the correct parameters is very important. For warranty purposes the correct CommScope fiber parameters must be set as they will be needed to ensure that the loss calculations estimated in the design phase are not exceeded. If standards parameters are set, because the losses acceptable are much higher, all the fibers may pass, but actually will fail when submitted for the CommScope warranty. It may be prudent to advise the customer, prior to testing, that the CommScope test parameters are more rigorous than the standards require and that these tests also support applications assurance. So, even though their system is running at 1Gb today, the fiber is designed to ultimately run at 10Gb with the correct transmission equipment, and will do so!

9: Steps for Field Loss Measurements.

Moving on to the actual process of testing, there are 5 steps that are required to perform an OLTS test.
1. Verify the test cord performance.
2. Choose a test method (1, 2 or 3 reference cords). Note that the 2 reference cord method is not generally recommended or included in the ISO/IEC 14763-3 standard.
3. Obtain a reference power level.
4. Measure the link power throughput.
5. And finally record the link attenuation.

10: Verify Test Cord Performance.

The performance of the test cords must be verified as follows:
1. Prepare the required launch cord with the necessary launch conditioner to meet the Encircled Flux launch conditions for multimode measurements or mode suppression loop for single-mode measurements.
2. Clean all test cords connectors and the test adapter per the manufacturer's instructions.
3. Follow the test equipment manufacturer's initial adjustment instructions.
4. Connect the launch cord between the light source and the power meter.
5. Record the Reference Power Measurement.
6. Disconnect the launch cord from the power meter.
7. Select the relative power measurement mode.
8. Connect the receive cord between the power meter and launch cord using the test adapter.

9. Record the Power Measurement. This measurement provides the attenuation of the receive cord cable (very minimal) plus the connection between the launch and receive cords. The measured attenuation must be less than or equal to the corresponding value given in the Table. Unacceptable attenuation measurements may be attributable to either of the test cords. Examine each cord with a portable video scope, and clean, polish, or replace if necessary.
10. Flip the ends of the receive cord so that the end originally connected to the power meter is now connected to the adapter, and the end originally connected to the adapter is now connected to the power meter.
11. Record the new Power Measurement. The attenuation must be less than or equal to the corresponding value found in the Table.
12. If both measurements are found to be less than or equal to the values found in the Table, the receive cord is acceptable for testing purposes.

13. Repeat this test procedure from the beginning, reversing the launch and receive cords in order to verify the performance of the launch cord. Remember to remove the existing launch conditioner or loop from the former launch cord and apply the same to new launch cord (formerly the receive cord).

11: Choose a Test Method.

Once the test cords are verified, you may test the fiber link. This is completed in two steps. As discussed earlier, there are three options for setting an optical reference between a source and power meter. These options may use 1, 2 or 3 jumpers, or Test Reference Cords. The method used is determined by your regional or vendor-specific requirements. A couple of things should be noted. Optical Loss Test Sets (OLTS) typically have a source and meter at EACH end so they measure two fibers at one time. For simplicity and clarity, the graphics here are only showing a simplex setup - one light source to one power meter (except in testing setup with 2 reference cords, that shows both links). When the term "test reference cord" is shown this means a cord with "reference grade connectors". These are connectors that provide much lower loss than standard connectors. Test reference jumpers are more expensive than regular patch cords.
A couple of final notes on referencing: Regardless of vendor or model, all optical sources should be allowed to warm up for about 5 minutes prior to performing a reference. On most optical loss test sets designed for Tier 1 certification, there will be a setting for "reference method". The physical configuration used to perform the reference MUST match the setting on the test device or your test margins are invalid. So if you set your test setup to do a three fiber reference but what you actually physically do is a one fiber reference, you have a completely invalid test result, especially your test margins are going to be completely invalid. NEVER disconnect the test jumper from the transmitter after a reference is performed; this will destroy the reference, you will need to do it again.
Always check your reference by connecting the source test jumper to the power meter test jumper and perform a measurement. There is some variation in what you would expect to see when checking your reference, based on the quality of your test jumpers and the reference method used, certainly below 0.3 dB. One thing you want to watch for when checking your reference is "gainers" - where your test set shows a loss with a positive value, plus 0.2 dB for example. That is also an indication that you've got a bad reference and you'll need to redo your reference.
It is a good practice to save your reference check to have proof that a good reference was established prior to testing. If during the course of testing you question your results, simply check your reference again and re-reference if needed, save the result and carry on testing.

12: When to Use Each Test Method.

The choice of which of the three reference methods to be used is determined by local standards, by vendor and if you are testing channels versus links. The difference between the methods is the number of connections that are referenced out of the actual loss measurement. In other words, after you perform a reference, and actually want to test, how many of the connections between your test jumpers and the fiber system under test are included in your loss measurement?
The diagram here tries to illustrate this: If a one fiber jumper reference was performed, both test connections to the system under test will be included in the loss measurement. If a two fiber jumper reference was performed, only one test connection to the system under test will be included in the loss measurement. If a three fiber jumper reference was performed, none of the test connections to the system under test will be included in the loss measurement. Also, depending on the end terminations of the system under test, a test reference is recommended.
If the system has adaptors on both ends, then use the one reference cord method. If the system has two different end terminations, a plug on one end and an adapter on the other, then the two reference cords method is preferable. Lastly, for the case with plugs on both ends, use the three reference cords method.

13: When to Use Each Test Method.

The 1 cord reference method assumes the test equipment to have the same connector type as in the link under test. Most testers have the facility to change port connector types if required. If this is not the case a 2 cord or 3 cord method will have to be used. This is where an adapter lead (on one end) or adapter leads (on both ends) are used so that the link under test plugs into the correct connector type adapter. Note that the cord on the source side is not removed and therefore the source port does not need to be adjustable. A cord with different connector types on each end may be needed here to connect to the source port and the field connector.

14: 1 Jumper Method.

A one fiber reference uses one fiber - or test jumper - between the light source and the power meter. Note there are no couplers, bulkheads or other connections between the source and meter when the reference is performed. So ONLY the loss at the source-to-test jumper connection AND the test jumper loss are referenced out. Once the reference is performed, the test fiber is disconnected at the POWER METER. After you have done a reference, never disconnect your test jumper at the light source at your transmitter, it will ruin the reference and will need to be re-referenced. A test jumper is then connected to the power meter.
Now test jumpers are on the source and meter that need to connect to the system under test. If testing a channel you will need to use couplers at the end of the test jumpers. If testing a link, simply connect the test jumpers to the system under test at the bulkheads. This is the fiber reference method required for link testing for TIA standards. TIA-526-14A (for multimode fibers), and 526-7 (for single-mode fibers), CENELEC and ISO use the 1-jumper method. Use verified jumpers, as we have just covered. Clean and select jumper 1, and install a mandrel/EF adapter for multimode or a loop for single-mode.
Set-up the OLTS, per the manufacturer's instructions, as in the graphic above. Note the value or zero the meter, if the equipment has this ability. NOTE: To improve the stability of the reference reading, and for easier handling, it may be helpful to secure the mandrel/EF adapter to the light source by some means such as a cable tie or tape. Care should be taken to ensure that the fiber jacket is not deformed or damaged when using a cable tie or tape. Take care of the test leads between measurements. Step 2 requires you to remove test jumper 1 from the meter and connect it to one end of the link. Connect a second verified test jumper between the other end of the link and the meter, as shown here. The optical power reading is taken.
The attenuation of the link is the difference in the power readings from step one and two. The 1 jumper reference for fiber is utilized for testing systems that end in a patch panel (any connector pair) on each end. This includes, by far, the majority of the premises systems. When cable runs do not end in patch panels and are directly plugged into transceiver equipment, it may be acceptable to utilize a 2 or 3 jumper reference. The 1 jumper reference method assumes the test equipment to have the same connector type as in the link under test. Some test equipment may not meet this requirement. For example, the test equipment may have ST connectors, when the link has SC or LC connectors. Or, more commonly, the equipment may have SC connectors, when the link to be tested has LC connectors. In this case, an adaptation is required.

15: 2 Jumper Method.

A two fiber reference uses two fibers - or test jumpers - between the light source and the power meter. Note a coupler is needed to connect the two test jumpers together. So the loss of the transmitter's connection to the source, the two test jumpers AND the loss of the connection between the test jumpers is referenced out. Once the reference is performed, the test jumpers are disconnected at the COUPLER.
Now you have test jumpers on the source and meter that need to connect to the system under test. If testing a channel you will need to add a coupler at the end of one of the test jumpers. If testing a link, simply remove the coupler used for the reference and connect the test jumpers to the system under test at the bulkheads. Two fiber reference is one of the least common references globally. It is the reference model that is most often done improperly.

16: 3 Jumper Method.

A three fiber reference uses three cords - or test jumpers - between the light source and the power meter. Like a two jumper reference, one test jumper is connected to the transmitter and one is connected to the receiver. In a three fiber reference, the third test jumper is placed in between, using two couplers to connect the transmit and receive test jumpers together. So the loss of the transmitter's connection to the source, the two test jumpers AND the loss of two connectors are referenced out.
The loss of the third test jumper is also referenced out but since fiber loss is very low this becomes insignificant. Once the reference is performed, the third test jumper is removed. If testing a channel, leave the couplers in place. If testing a link, remove the couplers and connect to the link under test. Three fiber reference is probably the second most common method used. It is quite commonly called upon when you are doing channel testing.

17: Multi-Fiber Inspection.

Having looked at single fiber connectors, multi fiber connectors are similar except there are many fibers in a single plug. Basically there are two sorts of MPO connector styles to be found, male and female. Of course they come in different densities from 8 up to 72 fibers but all in a single connector, and the fiber cleaning and inspection procedures are the same for each. The female connector as can be seen here has two holes on either side of the fibers for alignment but is basically a flat topped connector. A tap on the end with a finger could cause contamination and will need cleaning. The male has two pins for alignment so the end-face is partially protected, but at a first glance may be more difficult to clean and inspect.

18: Multi-Fiber Inspection.

There has been a rapid growth of MPO connectors in the data center field, and with that, different channel topologies. Let's look at three common scenarios here. This channel uses direct connections between two MPO style cassettes, breaking out into LC or SC connectors. Testing would normally be done through the connectors in the cassettes.

This next channel design uses a coupler panel to a cassette, so there become two elements that require testing. One is the MPO backbone and the other is the cassette.

The final channel design uses an MPO backbone through two coupler panels. Testing of these channels will be required for warranty and recording purposes but conventional fiber testing, connector to connector is not going to possible.

19: Multi-Fiber Inspection.

The requirement to have equipment that can test MPO backbones is essential. There are new MPO testers appearing on the market all the time. Let's look at some of the most popular ones. This is the MultiFiber™ Pro Optical Power Meter that comes from Fluke with three models available dependent on the wavelengths to be tested. It can automatically scan and test all fibers in an MPO trunk cable. Having set your known maximum loss limit for the trunk under test, these testers will test and record all the fiber cores in your link in 6 seconds. The simple user interface allows you to easily determine if the cable passes the loss criteria you set. Any fiber that has excessive loss will be easy to spot in the simple bar graph. The results can be uploaded onto the Fluke Linkware software.

Similar style test equipment from Viavi is the MPOLx - MPO tester. Wavelengths are selectable with this unit though and it also has full control and visibility at both ends, light source and power meter. Again a fast test time, 6 seconds, with pass/fail analysis and easy generation of certification reports using the Viavi FiberChekPro software.

20: Multi-Fiber Inspection.

EXFO take a different approach to testing here using your own mobile or tablet as the viewing device, together with a wireless inspection tool, fitted here with an MPO probe. Users can quickly and easily inspect all multiple- and single-row MPO connectors, without missing any fibers or dealing with the hassle of manipulating one or multiple scanning knobs, and while doing it right the first time.
The FIPT-400-MF uses a trigger to scan all fibers automatically. These features make it possible to inspect densely populated panels without having to disturb adjacent fibers that may be carrying information and all with one hand. Thanks to its onboard advanced software algorithm, ConnectorMax2 ensures that no fibers are skipped and performs automated pass/fail analysis within seconds. No need to follow fibers and count them manually; the interface will number each fiber automatically and assess the pass/fail status of the entire connector as well as each individual fiber. The results are saved and can be downloaded as required.

21: Multi-Fiber Inspection.

The third tester available is the Viavi (formerly JDSU) FiberChek Sidewinder. This is a completely automated solution to inspect and analyse every fiber of an MPO connector with speed and reliability. It has a touch-screen built in, but the fully automated part of the this unit, means that the screen will only really be used to really analyse a failed connector or for setup. Testing is simple, having set up the type of connector, MPO-12, single-mode or multimode, allows continuous testing through a panel. A pass is indicted by a high pitched alert while a fail with a low pitched one. The engineer only has to save the result if it's a pass, and does not need to inspect the results, which is ideal for most engineers tasked with carrying out multiple testing in a data center. The results can then be downloaded by Wi-Fi or USB to a PC or any mobile device using the Viavi FiberChek software.

22: Testers Verify Polarity in MPO.

Given the variety of polarity methods in pre-terminated channels, if testing an unknown system, that knowledge could be critical. Some testers from manufacturers like Fluke and Viavi can also verify the polarity, which will indicate to the technicians, the right type of cord to be used at each end, and also will provide guidelines for migration to parallel optics. Test equipment varies, so selecting the right equipment for the range of tasks you need to do is paramount.

23: Top-view Cross Section 12 Fiber MPO - Clean.

This is a cross-section animation of an MPO's coupling together and shows how the multiple fiber connector signal transmission works. The connectors physically mate together and in a clean, non-contaminated connection, light can transmit easily in both directions as required.

24: MPO Testing.

Testing for cleanliness of MPO connectors is essential. We referred to these connectors as 'plug and pray' in an earlier lesson as they are easy to contaminate, so it is in the interest of the customers and the installers that they are tested and proven before leaving site. Also mentioned earlier was the fact that quite often these connectors can be dirty although brand new out of the packet, as they can attract dust through static electricity especially if they are wrapped in plastic or cling-film type packaging.

25: Why Inspection is Essential for MPO.

Let's look more closely why inspection before connection is paramount. This is a the same cross-section we saw earlier and there is one small piece of contamination on one of the fiber cores. A patch cord is plugged into the MPO coupler which causes that single piece of dust to explode, creating contamination on to six other fibers and creating an air gap on the mating faces. This in turn creates back reflection and insertion loss, resulting in several channels down.

26: One Contaminated MPO Connector = Exponential Problems.

The 'pray' factor now comes in, as there are two connectors to be cleaned, inspected and cleaned again if required, with potentially the added pressure of an upset customer, and a task that should have taken two minutes now taking at least ten! If that cassette is in a fiber shelf, that time delay could be compounded even more if access to the MPO port is not easily accessible without removing it from the shelf.

27: MPO Inspection.

We have just looked at some examples of the automatic MPO test equipment on the market. There are manual options available too such as this one that has the ability to scan across the end-face of the connector, which is only about 10mm (3/8 inch) wide, and focus on each of the fibers in turn. The dual adjustable tip on the end of the probe allows the user to scan across the X axis or the Y axis of the connector and visually inspect each of the fibers. This is a close up of just two of the fibers, looking like fried eggs against a very lumpy background. In order for the connector to be good, all of these fiber ends must be clean.

28: MPO Inspection.

For cleaning MPO's, the best piece of equipment on the market is the pump stick cleaner as seen here. The cleaning tool is keyed to ensure the tip only fits one way onto the connectors and is able to clean both male and female ends by either using or removing the adapter on the end. This cleaner has a woven lint free tape roll that cleans the connector end-face when the tool is pumped. The gender of MPO connectors vary between manufacturers and components so this universal tool will cope with both. In a close up of the back of this module it can be seen that the connector is keyed and also the male pins are just visible inside. Because the cleaning probe is keyed it ensures that when cleaning male connectors, the tape cleans between the male pins without leaving any contamination on them.

An alternative cleaner is the Optipop Cassette cleaner which has a reel of cleaning cloth inside that is only exposed when a trigger is activated. There are two styles here. One allows the cleaning of all flat topped connectors, SC, LC or MPO female, while the second style accepts male MPO connectors with pins.

29: Wet Cleaning.

Dry cleaning MPO fiber connectors works in most cases but wet cleaning may need to be completed when the connectors are really dirty and dry cleaning won't solve the problem. Wet cleaning will involve fiber prep fluid and also stick cleaners, like firm cotton buds but smaller in diameter. The market is changing in relation to cleaning solvents, and fiber prep fluid which has been on the market for some years, is preferred over conventional Isopropyl Alcohol. The advantages are that it is non-flammable, leaves no residue or stains after cleaning and can be carried safely on planes if required.
The wet cleaning process involves wetting the appropriate sized tip in cleaning fluid and wiping the end of it ACROSS the array, NOT in line with it otherwise dirt will be transferred from one fiber to the next. If trying to clean connectors inside a cassette where there are two rows of fiber arrays such as an MPO-24, this becomes more difficult because you cannot help but touch an adjacent fiber core. Hopefully the wet cleaning process will have loosened or removed the contamination, but to complete the cleaning process, the end-face should be dried using a stick cleaner or similar which should now leave a totally clean end-face.

30: Inspecting Multi-Fiber Installations.

Careful cleaning of connectors and adapters is a top priority. It maximizes channel performance and can resolve many issues seen during system validation. Please review the videos in the download section of this lesson, that cover the cleaning of simplex and multi-fiber connectors.

31: That Completes This Lesson.

Welcome to Lesson 2 - Fiber optic transmission theory. We will take this lesson in two parts: Part 1 will include Propagation of Light through an Optical Fiber, Index of Refraction, Refraction vs. Reflection and Numerical Aperture. In Part 2 of the lesson we'll look at the more complex aspects of light propagation in fiber and the practical issues we have to deal with in data communication systems.

2: Optical Fiber.

First let's look at the optical fiber itself. This consists of a glass (fused silica) core surrounded by a cladding material - which is also a form of fused silica. Both parts play an essential role in transmission of light through the fiber and their properties have to be precisely controlled. A glass core without cladding is a poor means of channeling light. The types of fiber we will look at all have basically the same construction. The biggest differences are in their dimensions and the nature of the glass used in the core. The optical fiber types are multimode fiber and single-mode fiber.

3: Fiber Sizes.

The two types of multimode fiber most commonly used are 'graded index' types with 50 or 62.5 micron cores. The outside diameter of the cladding is the same for both types though at 125 microns. Graded index fiber has cladding that allows the light to travel along the length of the fiber in a consistent pattern, providing a good output to input ratio. Single-mode fiber has a much smaller glass core of 8 to 9 microns diameter but has the same outside diameter cladding of 125 microns. Single-mode fiber is most commonly used in longer distance cross-campus or wide area links and is usually used in telecoms and CATV type applications. As you can see, there is also a third type of cable, the multimode step index type, which you may find in some industrial installations. This has a much larger core of 200 microns diameter and the outside diameter of the cladding is between 250 and 380 microns. Step index fiber, unlike the graded index fiber, does not have such a good signal reflection off the cladding, meaning that the transmission of light through the core is more random and the output to input ratio is poor.

4: Light Path Within Optical Fiber.

The top diagram shows how light of different modes and wavelengths travels through the glass core of a multimode optical fiber. The light cannot escape because each time it strikes the cladding it is reflected back into the glass core. With multimode we can simplify things by thinking of the different modes of light as separate beams/rays passing though the core, reflecting with the cladding but without interfering with each other. Single-mode fiber does not allow light rays to enter at an a wide angle to its axis and reflect back and forth within the core. It only allows a single ray/mode of light to travel along the core of the fiber.

5: Light Propagation: Index of Refraction.

The light will stay within the core of a fiber because of differences in the indices of refraction (IOR) between the core and the cladding. The index of refraction of a material is a key parameter. It is simply the ratio of the speed of light in a vacuum to the speed of light in the material. Light travels at 186,000 miles/second in a vacuum. The speed of light in a glass fiber is about 127,000 miles/second!

6: Light Propagation: Refractive Index.

It follows that the higher the index of refraction for a material the slower light will travel through it. Here are some examples. The ones we are most interested in are the fused silica used in the core and cladding of an optical fiber. As you can see there are small but important differences in their indices of refraction - which mean that light travels faster in the cladding than the core.

7: Light Propagation: Critical Angle.

As well as the index of refraction, the other key parameter for light propagation in a fiber is the 'critical angle'. This is used to represent the minimum angle - from the perpendicular - at which light can strike the interface between two materials and be reflected back. In this example we are looking at the difference between air and water. Water has an index of 1.333 and air 1.003, so Theta in this case is 43 degrees. So as an example, when you are scuba diving in clear water, you can see what is happening on the surface directly overhead, but if you look at an angle of more than 43 degrees to the vertical you see reflections of what is happening below.

8: Light Travelling Through Optical Fiber.

Light will always change speed and direction when it moves from one substance to another. The index of refraction (IOR) for both core and cladding plus the angle of incidence determines whether reflection or refraction occurs. In an optical fiber we generally want all the light to be reflected back into the core. This is called total internal reflection. This ensures the light travels along the length of the core rather than 'leaking' into the cladding.

9: Light Propagation: Numerical Aperture.

To get total internal reflection, we have to ensure that light strikes the boundary between core and cladding at an angle greater than the critical angle. The angle the light strikes the boundary is determined by the angle it enters the end of the fiber, as shown. So, if the entry angle measured from the axis of the core is greater than the critical angle for the fiber, we won't get total internal reflection and the fiber will not work. To be transmitted along the fiber, light has to enter at an angle within the cone shown in red. The angle of this cone is called the Numerical Aperture - the NA. Mathematically, the Numerical Aperture is the 'sine' of the maximum angle that light can be coupled to the core and still be guided, or transmitted along, the core.

10: Cone of Acceptance.

The numerical aperture defines the Cone of Acceptance of light into the fiber. Light transmitted into the fiber outside this cone is lost. So, clearly the larger the cone the easier it is to couple the fiber with the light source. In practice, the numerical aperture of the fiber should be matched to the opto-electronics of the transmitter. The second diagram illustrates how some light from the optical source is lost and some is usefully propagated along the fiber core. An optical source 'sprays' light towards the fiber opening. Light enters the fiber at the correct angle (NA), but any refracted light is lost. Reflected light continues inside the fiber, total internal reflection occurs and light travels to the receiver.

11: Modes of Light Within a Fiber.

Having seen how light travels along a fiber, we can now explain the difference between single-mode and multimode fiber types. The complex properties of the glass in the fiber core creates 'pathways' for light in different wavelength bands. The core size and material in single-mode fiber is designed so that there is only one preferred pathway for light to travel though it. A multimode fiber can have more than 800 different modes or pathways for light. The theoretical number of modes offered by a fiber can be calculated using the equation shown, where 'd' is the core diameter and NA is the numerical aperture. To sum up these rules, shorter wavelengths and the larger the diameter of fiber or those with a larger NA, will result in more modes of light.

12: That Completes This Lesson.

Welcome to Lesson 2 part 2, Fiber optic transmission theory. In this part we will look at the theory behind some of the practical aspects of designing and using optical fiber in communications.

2: Light Transmission Fundamentals.

Starting with the very basics of data transmission through a fiber, a light pulse is transmitted at one end with a transmitter and received at the other end with a receiver. The transmitter has optoelectronics to convert an electrical signal into an optical one using a light emitting diode or a laser. The receiver has a light detector to convert the light pulse back into an electrical one. The difficult part is to ensure that the electrical signals that come out are the same as the ones that went in but when there are billions of pulses every second traveling over hundreds or thousands of meters, this is not so easy.

3: Attenuation.

There are of course factors that prevent perfect transmission. One of these is attenuation, which is the decrease in the strength of the signal as it passes through the fiber. This is measured in decibels per kilometer. A Bel is the ratio of input and output signal strength expressed as a power of ten so a decibel is a tenth of a Bel. The amount of attenuation occurring in a given fiber varies according to the wavelength of the light but in practice, the aim is generally to have attenuation as low as possible because that means we can transmit further before the power of the output signal drops so low that the receiver can no longer detect it.

4: Power & Attenuation Measured in Decibels (dB).

The term dB refers to attenuation equivalent to a percentage of the power lost in the link, while dBm refers to a power output or measurement level. This graphic illustrates what the attenuation expressed in decibels means. Examples: A loss of 1dB is equivalent to a loss of approximately 20 percent of the input power. A loss of 3dB is equivalent to a loss of approximately 50 percent of the input power. Power output is expressed in dBm and a power output of 0dBm is equivalent to 1mW. A single-mode CATV laser will typically have a high power output of greater than a milliwatt, and will therefore have a positive dBm power output rating (example: +5 dBm). A multimode source, such as an LED, typically has a lower power output of less than a milliwatt, such as -10dBm as an example.

5: Attenuation - Signal Loss.

Some light energy will always be absorbed by the glass core or scattered into the surrounding cladding. The amount of loss and attenuation from these effects depends on the materials used and the fiber manufacturing process. Whether power is lost within the core or escapes into the cladding, the end result is the same - less power at the receiver.

6: Intrinsic Attenuation.

As we have said, attenuation varies according to the wavelength of the light. As this graphic shows, this is not a linear relationship, or even a smooth curve. Due to water incorporated in the chemical structure of the glass core, there are certain wavelengths of light for that are absorbed to an exceptional degree. These blips in the wavelength/attenuation curve are known as water peaks. It makes sense to transmit light with wavelengths that avoid these peaks, as shown by the green bands. Different optoelectronic devices will be optimized to operate in these different wavelength windows, and vary in complexity and cost. Most fibers operate in the 850, 1300 and 1550 nanometre wavelength bands because of this.

7: Microbending.

Microbend loss refers to small scale 'bends' in the fiber, often from pressure exerted on the fiber itself. An example of this could be where the fiber cable has been compressed on a sharp edge such as running over the edge of a cable tray, creating a pinch point. The weight of other cables in the tray could help cause this or even a tight cable tie if the fiber has been pulled out of a bundle at an angle when it is installed and the other elements in the bundle press on it. Sometimes microbends can also be caused by manufacturing imperfections where coatings and buffers touch the fiber.

8: Macrobending.

Macrobends are bends that can be physically seen and easily identified. They are bends tight enough to change the angle at which light strikes the boundary between the core and cladding to a degree that some of it is refracted and lost - rather than being reflected as it should be. The two macrobend examples here are typical installation faults where the fiber has been bent at a tight angle. As we will see later, sometimes macrobending is introduced purposely into a fiber such as in test leads, where the amount of modes of light being transmitted through the fiber needs to be reduced.

9: Macrobending.

This list gives some sense of the importance of different types of losses. Ninety percent of losses are due to scattering of light out of the core while absorption accounts for just ten percent. Macrobending can potentially be a serious problem in installations if the bend radius of the fiber has not been observed while microbending is usually either a problem with poor manufacturing or a pinch point.

10: Attenuation Loss Budget.

To summarize the key points about attenuation in optical fiber: Attenuation of fiber is much lower than copper cable; Losses are usually expressed in dB/km; Different wavelengths of the light can be used for optical transmission; The total attenuation of the optical signal between transmitter and receiver determines the maximum fiber length and the number of connections in the link; Applications standards specify the allowable attenuation over a complete link. This Loss Budget is the total allowable loss in dB for all connectors, cables and splices for the application being run over it. e.g. 100BASE-SX, 1000BASE-SX etc.

13: Dispersion.

Now let's move on to another factor that can limit the distance over which a signal can be transmitted over a fiber link and deciphered at the far end - Dispersion. This can cause merging of separate signal pulses over the length of the link to the point where the receiver can no longer read them as separate pulses. The diagram illustrates how spreading of two pulses causes them to overlap and become, in effect, one pulse. In multimode fiber the dispersion is mostly caused by modal dispersion. A pulse of light is transmitted into the fiber but because with multimode (as the name suggests) there are 800 different modes of light being launched at the same time and all at slightly different angles, the light will travel through the fiber following different paths. Some may be straight in at 90 degrees, others 45 degrees and some at many other varied angles. This means the modes will arrive at different times too, so the receiver can't be too far away from the transmitter otherwise it won't know if it is receiving the first pulse or the second pulse as they start to overlap and blur together, causing the link to fail. In technical terms, pulse overlap = ISI (intersymbol interference) = bit error rates. The maximum distance through multimode fiber is therefore limited to 2 km.

To reduce the effect of the modal dispersion, graded index multimode fibers have a layered structure. This changes the refractive index of the core material according to the distance from its axis, allowing the reflections of the transmitted light to create a more predictable pattern. The modal bandwidth of a fiber is limited by the pulse broadening due to the differences in group velocities for the many propagating modes. These fibers are called graded index fibers.
For single-mode systems, the fiber has a much reduced core glass diameter, to a size where only one ray (or a single mode) can propagate through the fiber, so modal dispersion is not an issue. However there is still dispersion in single-mode fibers. Rather than modal dispersion, it is chromatic dispersion caused by the light source, which is not fully monochromatic. Single-mode fiber systems are generally more expensive, not because of the fiber cable, which is actually cheaper, but due to the cost of the interfaces and connectors. Single-mode connectors will be discussed in a later lesson. Single-mode light sources must have a narrow beam in order to couple light into this type of fiber, so as inexpensive LED light sources cannot do this, more expensive lasers must be used. The higher cost of active equipment in single-mode systems makes them less cost effective than multimode types for most 'local' or short range applications.

14: Signal Shape.

Here we can see how the sensitivity of the receiver determines the point at which it can no longer detect the difference between two pulses and one - or none at all. In the top diagram the pulses have started to merge but the receiver can still detect two separate peaks - so it reads the signal correctly as one-zero-one. In the second diagram the trough between the peaks is high enough to be counted as a one - so the signal is misread as one-one-one. In the third example, the signals peaks are attenuated to the point where the receiver does not detect them, so the signal is misread as zero-zero-zero.

15: Material Dispersion & Spectral Width.

As we have seen, the arrival times of signal components will vary according to how far they travel within the fiber, causing pulse spreading. This is an issue with multimode fiber. In addition to this, light of different wavelengths travels at slightly different speeds, so the light of some colors will arrive before others. The graphic illustrates the different speeds of different wavelengths. This effect also causes pulse spreading and is an issue with single-mode fiber systems. This material dispersion occurs because the spreading of a light pulse is dependent on the wavelengths' interaction with the refractive index of the fiber core. Material dispersion is a function of the source spectral width which specifies the range of wavelengths that can propagate in the fiber. Material dispersion is less at longer wavelengths as the impact of this can be reduced by using sources that produce light in a narrow wavelength band.

The power of laser sources is concentrated in a narrower band than an LED - but the extra transmission performance this gives generally comes at a higher price. The spectral widths of LEDs and lasers are dramatically different - as shown here. The emitting power of an LED is, typically, spread across a 170 nanometre wavelength band. For a laser, the power is concentrated in a wavelength band just three nanometers wide.

16: Mode Field Diameter.

In single-mode fiber systems, the amount of light, the optical power transmitted through a single-mode fiber, is not the same across the diameter of the fiber. To account for this, we use a parameter called the Mode Field Diameter (MFD) of a fiber. This is defined as the diameter at which light intensity drops to 0.135 of its peak. This is more relevant to fiber matching than core diameter, but this effect will cause dispersion as the light is traveling at different speeds in the core and cladding. Surprisingly the MFD is larger than the core diameter and up to 30 percent of the optical power in a single-mode fiber travels through the cladding. Typical MFD values for a single mode fiber are: 9.3 micron @ 1300nm; 10.5 micron @ 1550nm.

17: Waveguide Dispersion.

Waveguide dispersion is the dispersion caused by the cross-sectional distribution of light within a fiber and is based on the fact that the distribution changes for different wavelengths. Shorter wavelengths are more completely confined to the fiber core, while a larger portion of the optical power at longer wavelengths propagates in the cladding. Since the index of the core is greater than the index of the cladding, this difference in spatial distribution causes a change in propagation velocity. In multimode fibers, waveguide dispersion and material dispersion are basically separate properties. Multimode waveguide dispersion is generally small compared to material dispersion so waveguide dispersion is usually neglected.

18: Chromatic Dispersion can be Minimized.

The impact of chromatic dispersion is the combined result of material and waveguide dispersion. At the top we see how one pulse is separated into several of different colors during transmission. To the receiver, these separate pulses look like one spread pulse. As well as emitting in a narrow wavelength band, transmitters can be designed to minimize chromatic dispersion by emitting light at a wavelength at which the fiber gives zero dispersion.

19: Chromatic Dispersion in Single-mode Fibers.

Many single-mode transmission systems operate at 1310 nm with a loss of about 0.34 dB/km, but importantly its dispersion is zero. However because the fiber's attenuation is lower at 1550 nm, there is a trend for newer systems to operate at the longer wavelength but mostly in long haul TELCO systems. Different single-mode fiber types have been developed that optimize the chromatic dispersion at either of the two bands - 1310 and 1550.
Multimode fiber also experiences chromatic dispersion but this effect is generally less significant than modal dispersion. With LEDs it can cause bandwidth to be much lower than the modal bandwidth of the fiber. Even with lasers the chromatic bandwidth can still have significant effect, especially at 850 nm.
Chromatic dispersion also causes 'Mode Partition Noise' in laser systems. This noise is like chromatic jitter, and is caused by the time varying spectral output of the lasers among the spectral lines in their output as the laser is modulated. Mode Partition Noise is very significant for certain applications such as some fiber channel apps and some extended distance applications.
PMD - Polarization Modal Dispersion - is another factor that can degrade signal quality. This is usually seen over long distances and does not have a significant effect within most enterprise-length systems. 1310 nm is a fairly optimal wavelength for single-mode systems because of the low dispersion point and low attenuation, and 1310 nm lasers are significantly less expensive than 1550 nm long haul ones.

20: Dispersion Summary.

To summarize this section of the presentation, pulse spreading is the enemy of efficient transmission, limiting both maximum data rates and transmission distances. Modal dispersion is the major cause of pulse spreading in multimode fibers but it can be minimized though careful control during the manufacturing process. In single-mode fibers, chromatic dispersion dominates. It is caused both by the material used in the core and the change in the effective index for light of different wavelengths. It can be countered by using a monochromatic light source tuned to transmit at the zero dispersion wavelength of the fiber.

21: Dispersion vs Bandwidth.

Dispersion and the resulting pulse spreading limit the frequency or bit rate at which signals can be transmitted through a fiber, and the bandwidth is inversely proportional to this dispersion. At higher frequencies with more pulses in a given time period, the pulses have a greater tendency to merge due to dispersion, so to avoid this there is a maximum frequency at which transmission can be allowed. The bandwidth in which signals can be read accurately is limited by this maximum. Bandwidth determines the maximum rate at which pulses (bits) can be successfully transmitted through a fiber and hence its information carrying capacity. Bandwidth is normally given in units of megahertz kilometers (MHz-km). You can see from this illustration how higher frequency exacerbates the merging of pulses getting worse over distance. It shows how the bandwidth is dependent on the frequency or bit-rate, and the distance or length of the fiber link. Hence for a given bandwidth of fiber, the distance over which a signal at a certain bit-rate can travel, can be established.

22: That Completes This Lesson.

In this next part of the lesson we will cover single-mode fiber in more detail.

2: Optical Frequency Response.

A glass fiber consists of a core where most of the light is transmitted, and cladding, which is a different glass composition surrounding the core. Both core and cladding have an effect on signal propagation in fiber, with each having distinctive refractive indices, which are measures of the tendency of light to bend as it encounters a boundary. Four factors contribute to signal attenuation in a glass fiber:

Scattering is the directional and time variation of emitted light caused by collisions of molecules in the fiber with photons in the light being transmitted. Its effect is most prevalent at the shorter wavelengths in the optical spectrum.
Absorption is the conversion of light energy into heat energy. Atomic resonance effects at the longer wavelengths of the optical spectrum cause absorption to increase in that range of wavelengths.
Chromatic dispersion (CD) effects are the result of the refractive index of the glass used to construct a fiber. They are the set of signal velocity-related effects caused by changes in the refractive index of the glass fiber as wavelength changes. Chromatic dispersion is the sum of material dispersion and waveguide dispersion. Material dispersion is caused by material-specific properties that change the refractive index of glass as wavelength changes. Waveguide dispersion is a change in signal velocity caused by differences in the refractive indices of a fiber core and its cladding.

Finally, the water peak is an area of spectrum around 1380 nm where absorption by hydroxl ions causes a spike of signal attenuation. We will cover these in more detail as the lesson progresses.

3: 1310 & 1550nm.

Standard single-mode fiber has zero chromatic dispersion near 1310 nm because waveguide and material dispersion cancel out at that wavelength. This same effect can be shifted to 1550 nm by changes in fiber doping and/or cladding. The combination of low scattering and absorption plus zero chromatic dispersion yields two wavelength windows where conditions for transmission are very favorable. There are three basic wavelengths used for optical communications over glass fiber with 850 nm being the first window of transmission, and 1310 and 1550 nm being the second and third respectively.

4: Wavelength Bands.

Over time, improvements in fiber optic manufacture have removed the water peak from the spectrum, resulting in a continuum of frequencies that can be used for fiber optic transmission.

This continuum is subdivided into bands, as shown on the chart. The C band is of particular interest, in that it is an area of spectrum where Erbium Doped Fiber Amplifiers are implemented. This technology allows direct amplification of light, without an intermediate conversion to electrical energy.

5: Doped Fiber Amplifier.

Doping is a manufacturing process where ions of a selected element are added to the core of an optical fiber. When a fiber is prepared in this way, it can be made to amplify an optical signal by a technique called 'pumping'. Pumping occurs when a light from a high power laser called a pump is multiplexed with an optical signal from a laser source into a doped fiber. The photons in the light stream from the pump excite the doping ions in the doped fiber to a higher, unstable energy state. As those ions decay back to their original state, they emit photons at the signal wavelength, in the same phase and direction as the signal wave. The result is an amplified signal.
The photons emitted by the decaying ions have energy levels that are particular to the type of ion, and by careful selection of the ion, the emitted photons will correspond to the desired wavelength needing amplification. The range of spectrum where this emission occurs is called the amplification window. This window is also influenced by the structure of the optical fiber, and the wavelength and power of the pump. Erbium ions produce an amplification window in the 1550 nm range, and this is where an EDFA (Erbium Doped Fiber Amplifier) can be used. The pumping laser for an EFDA typically operates in the 980 nm or 1480 nm spectrum band. Because the 1550 nm window is one of the three favorable windows for fiber optic transmission, EFDAs are the most widely implemented doped fiber amplifier.

Optical amplification can also be achieved by other technologies, including the Raman amplifier, which uses laser pumping and the Semiconductor Optical Amplifier that uses electrical pumping.

6: Wavelength Division Multiplexing.

Just as frequency division multiplexing increases the signal-carrying capacity of metallic conductors, it's possible to improve fiber optic signal capacity by simultaneously transmitting different wavelengths over the same fiber. The wavelength must remain within specified frequency limits, and receivers need to be sufficiently sensitive to separately detect the individual streams of light.
The initial implementation of wavelength division multiplexing in fiber used 1310 nm light in one direction, and 1550 nm light in the other direction. This scheme is still in use, but improvements in laser transmitters and detectors along with better fiber manufacturing technology have greatly enhanced the number of wavelengths that can share a fiber.

7: Spectrum.

Starting at 1310nm, new wavelength transmission bands were introduced, first focusing on the 1550nm band for lower fiber attenuation. Finally the International Telecommunication Union (ITU) standardized transmission wavelength bands for optical communication over the entire wavelength range between 1260nm and 1675nm (O-, E-, S-, C-, L and U-band, supporting Wavelength Division Multiplexing (WDM) techniques from 1260nm to 1625nm).

8: CWDM.

Course Wavelength Division Multiplexing, or CWDM, is an enhancement to Wavelength Division Multiplexing. ITU-T G.694.2 specifies 18 wavelengths across 5 wavelength bands, with center frequencies separated by 20 nm. Notice that the 1390 nm wavelength coincides with the fiber optic water peak area (E band) of the spectrum, but this is not an issue as we will see later. In CWDM systems, the separation of frequencies is wide enough to allow a relatively large tolerance in the actual frequency of operation, allowing the lasers used for these systems to be economically manufactured and used in several communications applications for distances up to 50 km.

9: DWDM.

In the same year the ITU specified CWDM, it also defined Dense Wavelength Division Multiplexing, or DWDM. Unlike the specification for CWDM, ITU G.694.1 specifies DWDM wavelength spacing in terms of frequency rather than wavelength. The most commonly implemented DWDM systems use 100 GHz and 50 GHz spacing, which roughly equates to less than 3.2 nm between wavelengths. It was originally defined for operation in the C band, where erbium doped fiber amplifiers operate, although these systems have also been designed for other bands. The center wavelength in the DWDM C band grid is 1553.52 nm. Due to the extremely narrow spacing between wavelengths, lasers used in DWDM systems must be tightly controlled, and this adds substantially to their cost.

10: Fiber Types.

The optical fiber network infrastructures installed today will typically see four generations of transmission systems over the network's expected lifetime. As recent history has shown, the amount of data traffic these networks will carry will increase dramatically and continuously. A completely open spectral transmission window from 1260nm to 1625nm for data transmission and up to 1650nm for network monitoring is necessary in optical fiber cables in order to cope with this increasing growth. Cable type testing needs to extend to 1625nm to guarantee cable performance at the higher wavelengths, where macro- and micro-bending loss may obscure the attenuation limits of cables under severe circumstances.
The latest bend-improved fibers (G.657) support this optimization, particularly for demanding cable designs. In principle, optical fibers offer a tremendous amount of potential transmission bandwidth or capacity, currently used for a wide range of applications, such as long-distance data transmission (e.g. internet traffic), fiber-to-the-home and cable television. Maximizing transmission capacity, requires optimized fiber designs and communication techniques, which have been developed over the last decades in multiple steps, beginning with increased bit rates in telecommunications applications. Let's take a closer look at optical fiber's main parameters and characteristics.

11: Fiber Types.

The advantage of single-mode fiber is its higher performance with respect to bandwidth and attenuation. With proper dispersion compensating components, a single-mode fiber can carry signals of 10 and 40 Gbps or above over long distances. The system carrying capacity may be further increased by injecting multiple signals of slightly differing wavelengths (WDM) into one fiber. The small core size, which typically ranges from a core of 8 to 12 micron with a 125 micron cladding, generally requires more expensive light sources and alignment systems to achieve efficient coupling. In addition, splicing and connectorization are also somewhat complicated, but nonetheless, for high performance systems or for systems that are more than a few kilometers in length, single-mode fiber remains the best solution.

The peak identified in the graph indicates that at the wavelength of 1383 nm, the presence of hydrogen and hydroxide ions in the fiber optic cable material causes an increase in attenuation. These ions result from the presence of water that enters the cable material through either a chemical reaction in the manufacturing process or as humidity in the environment.

The variation of attenuation with wavelength due to the water peak for standard single-mode fiber optic cable occurs mainly around 1383 nm, but advances in the manufacturing processes of fiber optic cable have overcome the 1383 nm water peak and is known as Zero Water Peak (ZWP) OS2 fiber. We earlier saw, in the CWDM section that the 1390nm wavelength coincided with the fiber optic water peak area (E band) of the spectrum. This is where the advantages of ZWP fiber come into play.

12: Fiber Transmission Characteristics.

Another factor that affects the signal during transmission is dispersion, which reduces the effective bandwidth available for transmission. Three main types of dispersion exist: modal dispersion (MD), chromatic dispersion (CD), and polarization mode dispersion (PMD). The bandwidth of the fiber determines the maximum rate at which information can be transmitted through the network, and can be divided into two main components - modal and chromatic - both of which contribute to the total bandwidth.
Crosstalk does not occur in the fiber itself as the bandwidth of fibers is mainly limited by their dispersion. Depending whether it is single- or multimode, the system performance is determined to a different degree by the combined effects of modal and chromatic dispersion. For single-mode systems, other factors such as Polarization Modal Dispersion and Non-Linear effects must be considered, but these are more apparent for long distance transmission systems.

13: Chromatic Dispersion.

Zero dispersion wavelength, expressed in nm, is defined as a wavelength with a Chromatic Dispersion equal to zero. Operating at this wavelength does not exhibit CD but typically presents issues arising from the optical nonlinearity and the four-wave mixing effect in DWDM systems. The slope at this wavelength is defined as the zero dispersion slope. Both the dispersion coefficient (standardized to one kilometer) and the slope are dependent on the length of the fiber.

CD primarily depends on the manufacturing process, so cable manufacturers have to consider these effects when designing different types of fiber for different applications and different needs, such as standard fiber (G652), dispersion shifted fiber (G653), or non-zero dispersion shifted fiber (G655/656).

14: Polarization Mode Dispersion (PMD).

Polarization mode dispersion (PMD) is a basic property of single­mode fiber that affects the magnitude of the transmission rate. PMD results from the difference in propagation speeds of the energy of a given wavelength, which is split into two polarization axes perpendicular to each other (as shown in the diagram). The main causes of PMD are non-circularities of the fiber design and externally applied stresses on the fiber.

15: Causes of PMD.

Other causes of polarization mode dispersion within a fiber can be either intrinsic or extrinsic. Intrinsic means that the PMD is innate in the fiber and was caused during the fiber's manufacturing process, such as imperfections in the fiber's geometry or stresses that are within the fiber.

Extrinsic means that the PMD is due to a physical stress in the fiber after it has been manufactured, such as twisting, bending, or an external induced stress.

16: Other Non-linear Effects.

High power level and small effective area of long haul, single-mode fiber systems mainly cause what are known as nonlinear effects. With an increase in the power level and the number of optical channels, nonlinear effects can become problematic factors in transmission systems. These effects are dependent upon the nonlinear portion of the refractive index and cause it to increase for high signal power levels.

Behind an erbium doped fiber amplifier (EDFA), the high output can create nonlinear effects, such as (Four Wave Mixing (FWM), Self Phase Modulation (SPM), and Cross Phase Modulation (XPM). We will look more fully at these later in the lesson.

17: Dispersion Effects on Digital Transmission.

In digital transmission, the 'in lane' problem (too much dispersion) is the spreading of pulses that causes bit errors. Here the light from the '1s' disperses into the bit period of the '0' to the extent that the receiver mistakes the '0' for a '1' - a bit error. At this point either regeneration of the signal or compensation for dispersion is required.

On the other hand, too little dispersion allows the photons from signals in different channels (the 'cross lane' problem) to interfere with each other (a phenomenon called Four Wave or Four Photon Mixing - FWM) and create unwanted byproducts, as shown here. These byproducts cause two problems: 1. they rob power from the main signals (a minor problem) and 2. they can be situated at a signal wavelength and cause interference or crosstalk. Here you can see unevenly spaced signal wavelengths to illustrate the FWM mixing, but real systems have evenly spaced wavelengths where the unwanted byproducts would interfere directly.

Four Wave Mixing or FWM is an interference phenomenon that produces unwanted signals from three signal frequencies known as ghost channels that occur when three different channels induce a fourth channel. There are several ways this can happen, so let's look at two of the most common. Due to high power levels, and depending on the number of actual signal channels, FWM effects produce ghost channels, some of which overlap the actual signal channels. For example, a 4-channel system will produce 24 and a 16-channel system will produce 1920 unwanted ghost channels. Therefore, FWM is one of the most adverse nonlinear effects in DWDM systems.

In systems using dispersion-shifted fiber, FWM becomes a tremendous problem when transmitting around 1550 nm or the zero dispersion wavelength. Different wavelengths travelling at the same speed, or group velocity, and at a constant phase over a long period of time will increase the effects of FWM. In standard fiber (non-dispersion-shifted fiber), a certain amount of chromatic dispersion occurs around 1550 nm, leading to different wavelengths having different group velocities, reducing the FWM effects. Using irregular channel spacing can also achieve a reduction in these effects too.

18: Self Phase Modulation.

Self Phase Modulation (SPM) is the effect that a signal has on its own phase, resulting in signal spreading. With high signal intensities, the light itself induces local variable changes in the refractive index of the fiber known as the Kerr effect. This phenomenon produces a time-varying phase in the same channel. The time-varying refractive index modulates the phase of the transmitted wavelength(s), broadening the wavelength spectrum of the transmitted optical pulse. The result is a shift toward shorter wavelengths at the trailing edge of the signal (blue shift) as well as a shift toward longer wavelengths at the leading edge of the signal (red shift).

The wavelength shifts that SPM causes are the exact opposite of positive Chromatic Dispersion. In advanced network designs, SPM can be used to partly compensate for the effects of chromatic dispersion.

19: Cross Phase Modulation (XPM).

Cross Phase Modulation (XPM) is the effect that a signal in one channel has on the phase of another signal. Similar to Self Phase Modulation, XPM occurs as a result of the Kerr effect. However, XPM effects only arise when transmitting multiple channels on the same fiber. In XPM, the same frequency shifts at the edges of the signal in the modulated channel occur as in SPM, spectrally broadening the signal pulse.

20: Attenuation & Dispersion of Various Fibers.

This plot shows the attenuation and dispersion of the various types of single-mode fiber. The attenuation is on the left axis, and the dispersion is on the right axis. The units of dispersion are measured in picoseconds per nanometer kilometer. This means it's the delay time (in picoseconds) when one nanometer width of light is transmitted one kilometer, and is the total time from when the light began to be received to when it finished being received.
Fiber type G.652 (both matched and depressed clad) has the zero dispersion wavelength at 1310 nm, which this is the wavelength at which it is usually used. Fiber type G.653 (dispersion shifted) has its zero dispersion wavelength at 1550 nm, and again, this is the wavelength at which it is usually used. The other G.655 fiber (non-zero dispersion shifted) has a small amount of dispersion at 1550 nm.

We mentioned Erbium Doped Fiber Amplifiers (EDFAs) earlier in the lesson, and these usually operate in the lowest loss region of an optical fiber - the 1550 nm window.

21: Standards for Fiber Optic Systems.

Many international and national standards govern optical cable characteristics and measurement methods, but the two main groups that work on international standards are the IEC and the ITU. The IEC is a global organization that prepares and publishes international standards for all electrical, electronic, and related technologies, which serve as a basis for national standardization. The IEC is composed of technical committees who prepare technical documents on specific subjects within the scope of an application in order to define the related standards. For example, the technical committee TC86 is dedicated to fiber optics, and its sub-committees focus on specific subjects such as SC86A for Fibers and Cables, SC86B for Fiber Optic Interconnecting Devices and Passive Components, and lastly SC86C for Fiber Optic Systems and Active Devices.

22: Standards for Fiber Optic Systems.

The ITU is an international organization that defines guidelines, technical characteristics, and specifications of telecommunications systems, networks, and services. It includes optical fiber performance and test and measurement applications and consists of three different sectors: Radiocommunication (ITU-R); Telecommunication Standardization (ITU-T); Telecommunication Development (ITU-D).

23: Single-mode Optical Fibers.

The workhorse among installed single-mode fiber is category G.652, the first edition being standardized in ITU-T in 1984 and developed over time, to the most current sub-category, G.652.D. This fiber category is by far the most widely installed globally.

For several years ITU-T G.652 (cabled) fiber recommendation incorporated the C- and L-band extensions with (cabled) attenuation attributes at 1625nm resulting in a wide transmission spectrum from 1260-1625nm. This wide optical spectrum is used in optical telecommunication: Terrestrial Long Distance, Submarine, Metro-, CATV- and FTTH networks. Similar fiber types have also been standardized by the IEC. IEC SC86A not only standardized (bare) fiber types (60793-2-50 series), but also developed a full scale of cable types (indoor, outdoor, aerial and micro-duct cable) serving a extensive range of applications (60794 series of standards). In addition, IEC developed a wide variety of testing methods for cable types, acting globally as the main cable test methods.
The other commonly used fiber types used in telecom networks are:
G.653 zero dispersion shifted fiber, optimized for the 1550nm window;
G.655 non-zero dispersion shifted fiber, optimized for the 1530 to 1620 nm window;
G.657 bend insensitive fiber which we will discuss in more detail in the following section.

24: Single-mode Optical Fibers.

As discussed earlier, macro-bending loss is caused when the fiber is under constant bend radius. An optical signal, traveling through the fiber core, can lose a fraction of its power in a bent fiber; the tighter the bend radius, the more optical power is lost.

Macro-bending loss in single-mode fibers is characterized by a relatively strong increase in loss above a certain wavelength.

Micro-bending loss is caused by longitudinal perturbations of the fiber, usually related to intense contact of cable materials to the optical fiber (e.g. shrinking effects in tight buffered cables or less optimized loose tube cable designs). Micro-bending loss usually shows less wavelength dependency compared to macro-bending loss.

25: Single-mode Optical Fibers.

Particularly in older cable types, increased loss could be present at higher wavelengths due to macro- and/or micro-bending effects, in particular at 1625nm (and certainly at 1650nm for monitoring applications).

26: Single-mode Optical Fibers.

In order to overcome such bending effects, a category of bend-improved single-mode fibers was standardized by ITU as G.657 fibers. 4 classes of fiber are defined in the latest ITU-T G.657:
G.657A1: these are G.652D fibers with optically specified bending radius of 10 mm;
G.657A2: these are G.652D fibers with optically specified bending radius of 7.5 mm;
G.657B2: these are not compliant to G.652D, with optically specified bending radius of 7.5 mm;
G.657B3: these are not compliant to G.652D, with optically specified bending radius of 5 mm.

Of these fibers, sub-category G.657.A2 fibers offer the lowest bend losses (both macro- as well as micro-bending) while still being fully compatible with G.652.D fibers. These fibers can be used for a wide range of demanding applications and cabling structures, from access networks to fiber-to-the-antenna cables. A very special application for G.657 fiber cable is high optical power distribution, e.g. for central office patch cords (used for Raman gain applications, extensive DWDM or high power video overlay).
Light stripped off from the fiber core under fiber bending, will be absorbed in the coating. At higher powers, this may lead to overheating of the coating and in extreme situations to catastrophic failures of the coating resulting in fiber breakage, or even worse within a central office, fire. G.657.A2 fibers offer the best bending immunity for such applications.

27: That Completes This Lesson.

Welcome to Lesson 5 Fiber optic connectors. This lesson covers fiber optic connector technology, design, construction and use.

2: Optical Fiber Connector Agenda.

A communication channel is only as strong as its weakest links and inevitably, usually the connectors will be the weakest link. The interface between two fibers will always have some losses but these can be minimized by careful choice and fitting of connectors. In this lesson we will look at the technologies, techniques and performance of optical fiber connectors. All connector designs have the same objective. To provide an interface between two fibers that creates the least possible disruption of the signal passing along them. They also aim to maintain a connection under tension, bending forces and severe environmental conditions if necessary, for as long as it is required without degradation of its performance. Finally the connector must allow connections to be disconnected and reconnected many times without loss of efficiency.

3: Fiber Optic Connectors.

Fiber optic connectors come in several designs. Most manufacturers follow 'standard' designs with minor variations. However, there are some proprietary connector products in use. Nearly all fiber connectors are sized to fit either 900 micron tight buffered fiber or jacketed cordage. To position the fiber in the center of the connector, ceramic ferrules are customarily used. There are four common styles of connector used in the Enterprise market. These are the ST, SC, LC and MPO.

4: Color Identification Codes.

The TIA-598 color code for connector bodies and/or boots is beige for multimode fiber, blue for single-mode fiber, and green for APC (angled) connectors. Aqua is used for multimode OM3 or OM4 type fibers although quite often the connector attaching to it will be beige. This color code will normally be found on all the components of a channel, i.e the couplers above, which will be found in fiber shelves, fiber cassettes and patch cords. This color coding is there as an aid to help prevent mismatching of fiber types and components in a channel. Just to add to that, a new color (Erika Violet) for OM4 fiber has been introduced by some manufacturers. This new color scheme was rejected by the TIA-TR42 standards bodies though, as they stated color has never been used before to distinguish bandwidth grades, but it is used to distinguish core diameter 50/125, 62.5/125 and single-mode etc. Note: It is important that single-mode connectors, both standard and APC, should be used with couplers or adapter to match. To confuse things further, many manufacturers make connectors and couplers in a range of colors if differentiation is required for different networks on the same site for example. Let's look now at the most common types of connectors found in use today.

5: Fiber Optic Connectors.

This is the ST (Straight Tip) connector developed by Bell Labs back in the 1970's. It has a 2.5mm ferrule and is a keyed, sprung, bayonet style connector, so once the keyways are found, it pushes into position and twists to lock in place with the spring holding it tightly in position. These connectors are easy to handle and relatively inexpensive but only come in simplex versions so cannot be used to manage typical TX and RX transmission channel paths easily. Patch cords are available in duplex construction but it will be trial and error finding the correct transmit or receive coupler. These connectors are being used less and less as alternative connector types offer better performance and smaller size.

6: Subscriber Connector (SC) Connectors.

SC Connectors (Subscriber Connectors) were introduced to the market in the mid 1980's by NTT of Japan. Like the ST connector they have a 2.5mm ferrule but are a push/pull design about the same size as an ST, but lighter due to their plastic construction, sturdy, easy to handle, pull-proof when used with cordage and can be yoked together into a convenient duplex assembly. They offer excellent optical performance and are approved connectors in the TIA-568 cabling standards.

7: LC Connectors.

The LC connector was developed by Lucent Technologies as a small, low insertion loss connector. They are best described as Small Form Factor (SFF) connectors available in both simplex and duplex versions. The LC connector has a 1.25mm ferrule (half the size of an ST or SC) but offers superior optical performance. They have a sprung ceramic ferrule allowing them to mate effectively to couplers and fiber shelves using a latching mechanism similar to an RJ45 jack plug and because of their low loss they are commonly used on 10Gb fiber links and FTTA Fiber to the Antenna wireless applications.

8: Specialized APC Connectors.

The APC angled connector is used to connect single-mode fibers including applications such as broadband. Attaching a connector to a fiber will always cause some of the light traversing through the fiber to be lost. Regardless of whether the connector was installed in the factory or in the field, its presence will be responsible for some light being reflected back towards its source, the laser. These reflections can damage the laser and degrade the performance of the signal. The degree of signal degradation caused by Return Loss depends on the specifications of the laser, with some being more sensitive than others.

In an APC connector, the end-face is polished precisely at an 8-degree angle to the fiber cladding, so that most return loss is reflected into the cladding where it cannot interfere with the transmitted signal or damage the laser source. As a result, APC connectors offer a superior RL performance of -65 dB, whereas a standard ST connector would be -20dB. The higher this figure is, the better the return loss. These connectors are only available as pre-polished pigtails or in patch cords.

9: MPO (MTP) Connectors.

MPO, also known as MTP connectors, were developed by Nippon Telephone and Telegraph (NTT) and have 12 individual fibers with 250 micron spacing between them. They are a 'push on' factory terminated connector keyed to maintain the correct polarity. These connectors are designed for data center applications where speed of plug-n-play is required but they are becoming more common in equipment rooms of larger offices etc. They are designed for fast connections between data cabinets and are available in off the shelf lengths as required. Patch cords allow for the MPO spine cables to break out to conventional fiber connectors. The MPO connector is defined by IEC and TIA standards and is available in flat polish for multimode fiber and angled polish for single-mode.

The angled polish, like the APC connector we have just looked at, gives the connector much improved return loss. MPO connectors are also becoming common on the rear of fiber switches, but MPO components from different manufacturers may not be compatible and may yield incorrect polarity when mated, so always check the specifications with your supplier before purchase.

10: Fiber Adapters, Couplers & Cassettes.

Adapters are used to hold and align the end-faces of two connectorized fibers so that light can pass through the interface between them with minimum loss. Shown here are different types of adapters for fiber shelves or wall mounted enclosures. These include cassettes, couplers and adapter panels. Inside all of these are aligning tubes made of Zirconia for single-mode couplers or phosphorus bronze for multimode versions. These aligning tubes ensure the ferrules of the fiber connectors precisely align.
Sometimes split sleeves are used to allow for expansion of the material during connector mating and create a better alignment. Again as seen earlier, connectors and couplers should match the fiber type and the connector. Adapters for MPO/MTP connectors do not contain any alignment tubes but have pins to provide the precise alignment and keying but this requires the pinhole geometry to be very accurate to ensure repeatable connection/disconnections.

11: Fiber Adapters, Couplers & Cassettes.

The MPO trunking systems are available in 8, 12 and 24-fiber variants. These have evolved over time and now provide support for a large variety of network topologies driven by a constant shift in the economic options introduced by network equipment vendors. To enable identification of each MPO type easier, colored boots are used. MPO-8 have grey boots, MPO-12 black, and MPO-24 red. MPO connectors should not be color mismatched as the layout of the fibers in each type is different.

12: Ferrule - Based Mating.

The key component in quality connectors such as the LC, is the ferrule that holds the end of the fiber. Ferrules may be made of ceramic (zirconia), metal, or plastic (polymer composite). Ceramics are the most durable of the materials but are more expensive than plastic which tend to be used in cheaper connector versions. Plastic ferrule materials may 'shave off' during mating and re-mating, creating debris that must be cleaned off. Spring force within the connector causes the ferrule to push forward which helps ensure physical contact of the connector end-faces. Most connectors are keyed, and only allow the connector to mate in one orientation.

13: Side View - Cross Section.

There will always be some losses within a connection This will be at any point on the join where air or other material separates the glass faces of the fiber core or when fibers do not make contact over their full area of the core, but these potential sources of loss can be minimized by careful design and use of the right connector.
The loss of signal power in a connection is generally referred to as insertion loss and the TIA fiber standards allows a maximum of 0.75 dB for each connection, although most good connectors are much better than this. Out of the three most popular connectors in use today, ST, SC and LC, the LC connector has the lowest loss.
The most important source of losses in a connector is the Return Loss or Reflectance at the mating end-faces of the fibers. As the name implies, this loss is caused by part of the signal power being reflected from the interface back down the fiber. The return loss for an LC connector is about 55dB.

14: Insertion Loss.

Insertion loss - the optical power loss caused by inserting an optical component such as a fiber connector into an optical path, occurs because the end-faces of each fiber are not in close contact with each other over their full area, such as misalignment of fibers. The diagram shows a connection between two fibers that are not on the same center axis. This results in some of the power in the core of one fiber being fed into the cladding on the other. There are many factors that prevent perfect alignment at the joint face; most of them are the result of inaccurate manufacture, poor workmanship or excessive stress and wear.

15: Return Loss.

Poor fiber end-face geometry is another potential source of insertion loss. This diagram shows fiber cores that are not shaped and aligned properly. As a result, there is not full glass-to-glass contact and there are air gaps between the two faces that will cause reflectance, i.e. return loss.
There are many other geometrical imperfections of the end-face that can result in poor mating of the glass surfaces. These include protrusions, undercuts and poor polishing. The performance of connections with poor end-face geometry are likely to get worse under temperature extremes or after re-mating.
In extreme cases, where the ratio of reflected power to incident power is high, this can cause 'false' signals as power is reflected back and forth in the link. This is a particular issue for broadband video and telecom links and may become one for future high speed digital data connections. Cleaning of fiber ends is also a key area for control and process. Even a fingerprint can significantly affect the end-face quality and loss.

16: Keyed LC Connectors.

Today's facilities often employ more than one network and need mechanical security to limit access and prevent inadvertent cross-connection. The CommScope Keyed LC connectors and adapters offer a tamper-proof design, reducing the chance of unauthorized connections, and in order for a connection to be possible, the connector and adapter colors must match for it to work.

The CommScope Keyed LC adapters mount in the same footprint as a simplex SC adapter and is pull proof for patch cords. The small form factor is half the size of standard connectors and the single-fiber ferrule maintains proper polarity. Connectors and adapters are available in Behind the Wall, simplex and duplex jumper versions, come in ten distinct colors while a black universal key is available for use while testing.

17: Connector Types: Many Other Options.

The LC is established as THE small form connector on the market today. But you may still see other types in addition to the SC and ST. Here are some of them. They include the MT-RJ, which has an existing base but few new installations, the MU common in Asia and the SMA which is still used by the British military is some installations.
The SMA is not the best connector for losses; it uses a screw connector which means that repeatability of getting the connector exactly aligned every time is near on impossible to do.
The FC, also known as the FCPC connector, is used by telecom providers for long haul applications, while the e2000 connector is a bit like an SC 2.5mm ferruled connector with its own spring loaded dust cap.

18: Connector Termination.

As well as a variety of connector designs, there are various ways of fitting them. All of these are designed to achieve tight, full area contact between the fiber cores to minimize insertion loss. All factory terminated connectors utilize heat-cured epoxy for bonding. This method utilizes the lowest cost components, and the curing time can be offset by utilizing a batch process.
There are some other variations to list above. Other epoxies 'air' dry over a 24 hour period or use a UV lamp. One product holds the fiber in place by mechanical methods (crimp without epoxy) but then the end-face still needs to be polished. For field installation of connectors, anaerobic glues are the preferred bonding agent or alternatively, mechanical splicing is an option.

19: Epoxy & Polish Termination.

As we have seen, there are alternative methods of bonding fibers into connectors. Bonding with epoxy involves a two part glue that must be cured in an oven. Although this provides a very good bond, the practicalities of using an oven on site means that this type of termination method is normally used in a production or lab environment.

Far more common are anaerobic glues that cure on exclusion of air without need for anything else. The anaerobic glue process works within a minute and all that is required are the activator and primer which can easily be carried as part of an engineer's fiber tool kit.

20: Polishing.

Once the fiber's termination method has been decided on, polishing is required. For both the epoxy or anaerobic methods the termination and polishing methods are the same. Kits are available provided with all the necessary components, tools and consumable materials, alternatively you may have already your own tools, but most important is a decent quality microscope as end-face inspection of the ferrule is essential.

21: Endface Quality.

Interferometers are instruments that use polarized light to examine the profile of fiber end-faces, they make it easy to see defects and judge the quality of polishing but are used in labs and professional fiber polishing production and are too expensive and bulky for field use. However, they are utilized to evaluate polishing results and optimize polishing procedures before implementing a process in the factory or in the field.

22: Adhesive Termination: Polishing Steps.

The hand polishing technique is critical to the quality of a connection. The images from an interferometer are used to examine the fiber end-face and show the difference between good and bad polishing. Polishing in a circular figure of eight pattern produces a uniform face, so round patterns over 75mm or 3 inch will produce an optimum end-face. If the polishing technique is long and skinny over the same area, this will result in a irregular dome with the end-face being distorted.

23: Endface Quality.

Microscopes used to examine fiber end-faces should have a typical magnification of 400 times if they are to be useful in the field. The image on the right illustrates what you want to see when you look at the end of multimode fiber. The four images to the left show some of the things you don't want to see after polishing - scratching, chipping and broken ends. To see a good example of a polished connector end-face, look at a factory pre-terminated one on a fiber patch cord and then compare it to a hand polished version. We will cover inspection fully in a later lesson.

24: Pre-Polished Fiber - Stub Connectors.

Having just looked at connectors, there is another type available on the market which is called a pre-polished fiber stub connector or a pre-polished field installable connector. This is where a short length of fiber has been cleaved at both ends and then glued into a connector. The ferrule is then polished and is ready to accept a 900 micron fiber into the back end of the connector. Inside the connector is small amount of index matching gel that has the same refractive index as the fiber it will be mated to. The fiber connecting to it is cleaved to the required length and inserted into the rear of the connector, pushing into the gel, creating a good connection between the two fiber ends. If there was no gel, the connection would be poor as two dry surfaces together can cause problems. A clamping mechanism usually holds the fiber in place. The fiber connector is now finished!
Pre-polished fiber stub connectors do offer cost and convenience advantages in the field but the downside is that not all field-installable connectors are the same. Although there are several types available on the market, quality in manufacture is critical, so choose by a known manufacturer rather than by price. Although this point is really a design issue, you need to be aware when calculating losses on these types of connectors, there is the standard loss of the connector being used but you also need to add the 'mechanical splice' loss inside the connector. This could increase the loss on an overall link and should be taken into account in the design phase.

25: Example - CommScope Qwik II Connector.

The Qwik II is an example of this type of connector but requires no crimp tool for termination and has a visual indicator to confirm it is attached correctly. A VFL (Visual Fault Locator) can be used to perform this continuity check. Should the fiber need to be re-seated in the connector for any reason, the connector can be opened and the fiber re-inserted as required. The benefits of this connector is that it is available in SC or LC versions and in both single-mode and multimode versions. There is also a tool kit for all connector types, alternatively all that is required is a good quality cleaver along with basic fiber stripping tools.

26: The Qwik II Connector.

The Qwik II connector is supplied in its own disposable sprung holder that has a wedge built into it, to hold the connector open, ready to receive the fiber. Squeezing the sides of the holder retracts the wedge and closes the connector, clamping the fiber in place. By squeezing the holder again the connector can be removed. Should there be a problem, the connector can be placed back into the holder to reactivate the wedge. A video and instruction sheet for these connectors are available in the download area.

27: Jumpers / Patchcords & Pigtails.

Jumpers or patch cords are one or two fiber cables with connectors on either end available in wide variety of lengths and connector types. Reputable manufacturers supply these patch cords with test results as standard. Pigtails are pre-polished terminated connectors on a 1m length of 900 micron fiber available in single-mode or multimode with a choice of connectors. This length is usually ample for fiber management and are designed to be fusion spliced onto the end of internal or external fiber cables, either 250 micron or 900 micron as required. Please note that with the pigtails themselves, there are different types of 900 micron fiber jacket available, some of which can be kevlar buffered, so choose the correct fiber type and construction for your application.

28: That Completes This Lesson.

Welcome to Lesson 7 part 1, Fiber Cabling in the Data Center. The objective of this lesson is to review the challenges facing fiber design in the data center, understand how fiber products help solve these challenges and then review fiber design and installation.

2: Fiber in the Data Center.

Let us now look at fiber products that could be beneficial to use within the data center. OM3, OM4 and OM5 multimode cables, such as CommScope's LazrSPEED, support up to 10 Gbps over 550 meters using 850 nm VCSEL transceivers, affording extended distance or more tolerant connector counts than may be required in data center designs. They offer 1Gbps and 10Gbps serial support providing significant cost savings over long wavelength solutions. These cables can also provide support for higher speeds of 40Gbps and beyond over 100 meters distances. Multi-fiber pre-terminated solutions can potentially extend OM3, 4 and 5 into the 100Gbps signaling arena with parallel signal options as well as offering fast, compact installations.

OS2 single-mode cables, such as CommScope's TeraSPEED ZWP, support long wavelength, long distance interfaces and offer additional interface potential and options in the future that include CWDM (Coarse Wave Division Multiplexing).

Data center connectorization is recommended with either LC or MPO connectors, but cordage is available in ST/SC/LC/MPO, as well as hybrid options including MT-RJ to suit older data center equipment interfaces.

3: Backbone Trends - Multimode.

Laser Optimized multimode fiber enables the use of transceivers that are far less expensive, making the overall system cost lower than that of single-mode systems. Both industry standardized applications (shown in bold type) and non-standard transceivers are available. First designed for DC applications, and due to the speed, distance, and cost trade-offs, these have been optimized over shorter distances using multiple parallel fibers.
But as DC size and speeds have grown, technology has advanced, enabling 40G and 100G beyond 300m and 200m respectively. Multimode fiber is dominant for up to 10G and 300-500 m, and although the IEEE standards distances may be reducing for 40 and 100G, there is still plenty of reach to cover most building backbones up to 100G with the IEEE compliant specs up to 150 m on OM4, with several other options for extended reach on OM3 and OM4, as well as OM5 WBMMF.

4: Next Generation Multimode Fiber.

We have just mentioned OM5, this is the name for a new generation of multimode fiber that has been developed called WBMMF (Wide Band Multimode Fiber). As data rates have advanced, a technique called multiplexing has been successfully standardized to deliver higher rates for applications such as 40GE and 100GE, with 400GE and 128GFC also in development. All of these applications employ a type of multiplexing on multimode fiber, that involves dividing the data into lower speed constituents and conveying each over its own individual fiber within a multi-fiber cabling infrastructure, commonly referred to as parallel transmission. Recent developments will add an additional multiplexing dimension enabling multiplication of multimode fiber capacity, through the use of multiple wavelengths.

Through WDM (Wavelength Division Multiplexing) each additional wavelength expands the capacity of the fiber, enabling either a reduction in the number of fibers or an increase in total channel capacity. Existing multimode fibers have a limited ability to support high speed transmission using wavelengths outside the 850nm wavelength for which they are optimized. Wide Band MMF can support four or more wavelengths to significantly improve capacity. For example, this type of fiber can enable transmission of 100Gbps over a single pair of fibers rather than the four or ten pairs used today. It also supports some new systems being used in data centers such as Cisco's BiDi solution.

5: WDM Transmission.

Shortwave Division Multiplexing works by transmitting at four different wavelengths λ1 to λ4 through the fiber. The nominal values of these are shown in the second column of the table. The resulting plan starts with 853 nm which is a little shifted up from a typical normal wavelength of 850, and the wavelengths go up from there in increments a little larger than 30nm. Between each of these wavelengths there has to be a gap and these are called pass bands.
The pass bands increase regularly as they go up in wavelength and that is due to the wavelength scaling portion of the calculations. The result of these scaled pass bands and guard bands is a spectrum that is equitably divided for all the bands due to wavelength scaling. The nominal wavelength is shifted up slightly but it is still able to use the λ1 VCSELs that are designed for legacy applications because they fit within the 840 to 860 nm range. The longest wavelength is 953 nm and the shortest is 846, for a total span of 107 nm.

6: Total Bandwidth Comparison.

CommScope's LazrSPEED WideBand Multimode Fiber (WBMMF) enhances the ability of SWDM technology to provide at least a four-fold increase in usable bandwidth while maintaining compatibility with OM3 and OM4 fibers and supporting all legacy multimode applications. Because the specification retains the performance of OM4 at 850 nm, this wideband MMF will continue to support and comply with the requirements of existing applications while also enhancing and enabling support for low-cost VCSEL-based WDM applications in the future. By providing high bandwidth at longer wavelengths, this fiber also provides a means to support signals from faster VCSELs, opening the door to 50 Gbps lane rates and beyond.

7: WBMMF.

The color identification of this new fiber and all the components is lime green, not to be confused with APC connectors and components which are also green although they could be described as a bottle green color.

8: Trends - Single-mode.

Single-mode fiber is very high bandwidth, capable of long distance transmission, but has associated significant costs for the transceivers at either end of the link, making the total system cost relatively high. Historically, single-mode backbone cabling supports 10G (or higher speeds using Wavelength Division Multiplexing) on duplex channels and is terminated in the field with LC or SC connectors, but as technology has moved beyond 10G, parallel transmission over 8 fibers per channel is available both in 40G and in 100G which is specifically targeting cost-effective backbone implementations up to 500m.

9: Fiber Cables Indoor & Armored.

Fiber cables are offered in a variety of jacket types to suit local fire codes: plenum, riser and LSZH. In addition, these formats are offered in a pre-armored option available in LazrSPEED and TeraSPEED options. It may be useful in some data center designs to add physical protection to cables exposed under busy raised floors, for example between the ZDA (Zone Distribution Area) and EDA (Equipment Distribution Area), or within the EDA to equipment, or just for additional physical security and robustness, in MDA (Main Distribution Area) to Secondary, MDA Tie cables, or MDA to the Primary Entrance area.

10: Data Center Fiber Connectors.

The fiber connectors commonly used in data centers are the MPO as we have already seen, but also extremely common are LC or SC connectors, both of which can be duplexed. Most equipment manufacturers offer these fiber interfaces in both single-mode or multimode versions. The LC connector is now dominant in 10G interfaces due to its small size, reliability and consistent high performance due to its sprung ferrule ensuring good mateability. The MPO connector will be discussed in more detail in the second part of this lesson.

11: Data Center Fiber Design.

Let's now review fiber optic cabling design with respect to the data center.

12: Cabling Design.

Copper cabling design is fairly straight forward, as it is limited to a 100m channel length, has a standard connector type, will predominantly be used in the horizontal, is likely only to be of one performance specification and supports a single network type, namely Ethernet.
Fiber optic cabling design can be more complex as there are legacy connectors and interfaces, multiple performance demands, and is used from the EDA to HDA to MDA and Entrance and multiple networks. The design process phases should include calculating the fiber requirements per cabinet while allowing for growth and redundancy. The cable routes should be determined from cabinet to cabinet, and area to area, including the EDA to HDA, HDA to MDA, and MDA to Primary Entrance. In addition to this, any secondary or tie cable routes should be considered.

Wiring standards do limit the distance between the main cross-connect and closet, so distances may impact the choice of optical fiber and application interface. Determine also if there will be an interconnect or cross-connect at each termination point, or any required splicing points, and lastly determine the supporting structures required for additional lateral cable runs. Each of these key phases will require additional design considerations that we will now cover.

13: Cabling Design.

TIA-942 notes that the horizontal media distance shall be a maximum of 90m link and 100m channel, independent of media type. The maximum cabling distance in a data center not containing an HDA shall be 300m including cords for fiber cabling. Copper cabling is of course still limited to a 90m link and a 100m channel. Backbone media can, again, be copper or fiber but fiber is limited by application and fiber media choice.

14: Fiber Channel Design.

TIA and ISO standards provide some application distance guidance but only for minimum standards based products. CommScope fiber products meet and exceed the standards based worst case allowances, therefore significant design benefits can prevail. Additional distance, connectors and splices are allowed, providing the power budget of the application is not exceeded and bandwidth is taken into account. Therefore designs will need to consider the following steps. The current and future applications to be supported, the distances between interfaces, fiber bandwidth/performance, attenuation of cable and components, and lastly the administration requirements whether they be SC, LC or MPO, simplex or duplex.

15: Fiber Channel Design.

The CommScope Fiber Performance Specification covers pre-terminated fiber solutions and is an invaluable tool for fiber channel design. The specifications show the distances that applications are supported and warranted. They also take into account the impact of bandwidth on given-performance fiber and allow for expected connector and splice losses. It is also a very informative guide for applications and interfaces, and is specifically related to CommScope products.
Another key tool in fiber design is the Fiber Performance Calculator. This will tell you the expected dB loss for a given design in terms of actual fiber distance and the number and type of connectors and splices in the channel. If you use these two tools correctly, it will assure the channel is supported under the CommScope applications assurance program. The tools are updated on a regular basis, so you should refer to the CommScope website for the latest version.

16: Fiber Channel Design Review.

These two key tools are used as shown here. First step in a design is to establish the design draft by understanding the limiting requirements, for example the current and future applications to be supported, the distances and the number of mated connectors, and splices. Check the performance guide tables to ensure the applications will be supported over the distance required with the connectors and fiber proposed in the draft.
The table will provide maximum distances, so the next step is to take the 'actual' distances, chosen fiber type, connectors, and splices and feed these into the loss calculator to get a target worst case dB budget for your unique fiber link. This target figure should then be printed and given to the installation team so that they know what that figure is. A couple of additional tips when using the performance tables.
Firstly, note that you do not count connector loss at the equipment. This is already considered during interface design.
Secondly, read the other notes around the tables as these may refer to other topics such as the use of mode-conditioning patch cords.
Next, the link is installed and tested using an Optical Loss Test Set (power meter and source), not an OTDR.
The measured link loss should not be higher than the target budget figure. If it is larger, then something is wrong with the installation, as it should be fairly easy for competent fiber installers to easily achieve this figure. If the loss is too high, the link should be tested and analyzed with an OTDR to identify the problem. If the installed link loss is equal to or less than the target budget, then your application will be assured.

17: Loss Allowances.

The Fiber Performance Calculator (FPC) is a user-friendly Excel tool that aids the calculation of optical losses for fiber links configured with fiber components such as cables, connectors, splices, couplers, and different types of fiber modules. The FPC is used to help design the fiber infrastructure, as not all fiber types are the same, so the tool helps calculate useable distances. It can help you decide which fiber can be used to support a certain set of applications, and what distances a specific configuration can support. It takes into account how many connections the link can include for a given distance. It can also allow for details such as using TAP monitoring in a link.
Ultimately, the FPC details the losses you should expect from a specific fiber channel configuration. One other use of the FPC is to check the performance of an installed fiber cabling channel. This enables the test engineer to confirm whether the actual losses are below the maximum acceptable values. This will help determine if re-installation is required, and/or what applications can be supported over an installed link.

18: Loss Allowances.

The latest version of the Fiber Performance Calculator has a number of enhancements over previous versions. The number of module types available for the link configuration is now larger, with the addition of MPO8 and MPO24 connections (MPO12 was already an option). In addition, the modules are now categorized into Standard Loss, Low Loss and Ultra Low Loss (ULL), the latter being used for the High Speed Migration portfolio. New applications have been added to the Performance panel, showing the supported distance of a selected fiber link for each of the transmission protocols. This is provided the configuration is included in the SYSTIMAX Performance Specifications documents.
The FPC shows two sets of loss calculations if the configuration uses any non-ULL connectivity products. The top row shows the calculated losses for the selected configuration. The bottom row shows the attainable maximum losses if all non-ULL connections are replaced with their ULL equivalent connections. If only ULL modules are used, a single set of results is shown. This function therefore highlights the advantage of moving to ULL products.
The workflow has been improved to allow the user to modify the configuration, length or fiber type at any time. In order to ease the logging of losses for large installations (multiple runs with same configuration but different lengths), there is the option to calculate losses for this case. The interface will show losses only for the first length, but when copying the losses to the spreadsheets, all calculations for the multiple links will be logged. The tool detects the display resolution and adjusts the interface zoom accordingly.

19: Loss Allowances.

Let's start by reviewing the different areas of the FPC display and the functions.
Area 1 houses the zoom in and out buttons, and several other function buttons which allow access to examples, default settings, disclaimer statement, delete the configuration, and exit.
Area 2 has fields for the fiber link's label, start point and end point.
Area 3 lists the fiber types available for selection. One type can be selected for a link.
Area 4 is where you choose units of measure (m for meters, f for feet) and input the link length, the number of links (for multiple links with same configuration with different lengths) and the length increment. As an example, if you want to calculate losses for 10 links from 100 to 145 m, you enter 100 - 10 - 5 in these 3 fields. Changing any of these values will result in a recalculation of all results.
Area 5 is used where a configuration includes a TAP module (to deviate part of the optical signal to monitoring devices). If this checkbox is ticked, additional fields appear to enter the type of TAP (50/50 or 70/30) and the lengths from the start point to the TAP, and from the TAP to the end point.
Area 6 defines how the electronic equipment is connected to the first panel. If your electronic equipment (switch, server, etc.) is interconnected to the first fiber panel, click on the left image. If the fiber panel is mirroring the active equipment, click on the right image. The link diagram will then show the cables and patch cords entering the panel properly.
Area 7 houses the selection of connectors and modules that can be added to a link. You can choose up to 10 modules to configure your link, from left to right. The modules are categorized into Standard Loss, Low Loss and Ultra Low Loss (ULL), the latter being the High Speed Migration portfolio.
Area 8 is a function to enable you to remove the TAP module (if there is one) or the last module you added to your link.
Area 9 shows the configured link with the modules you have selected. You can delete the last one or add new modules whenever you want and the diagram will be updated.
Area 10 displays the calculated Maximum Allowable Losses for two wavelengths: 850nm/1300nm for multimode fiber and 1310nm/1550nm for single-mode fiber.
Area 11 displays the support for a broad variety of fiber applications.

20: Loss Allowances.

The 'plus' button at the right side of the link label changes the label in a numeric sequence. This is useful to avoid retyping the label in the case of many links to calculate losses for. The blue button at the left side of the loss results enables you to copy the configuration, calculations and supported applications to the spreadsheet report and updates the handout sheet in the Excel book. If you don't need the applications support data, you can hide the right performance pane with the button placed at the bottom-left of the application area.

21: Loss Allowances.

When using the FPC, there is no need to follow any strict sequence to input all data but if you wish to do so, the logical steps would be:
1: Enter the link name (you can also click on the 'plus' button).
2: Enter the inputs for labelling the start and end points.
3: Select the fiber type.
4: Choose your units (m for metric, f for imperial).
5: Input the link length.
6: If you're calculating multiple links, input the number of links (for multiple links with same configuration with different lengths) and the length increment.
7: Mark the checkbox if a TAP module is in the link, and then complete the extra fields to enter the type of TAP (50/50 or 70/30) and the lengths from the start point to the TAP, and from the TAP to the end point.

22: Loss Allowances.

8: If your electronic equipment (switch, server, etc.) is interconnected to the first fiber panel, click on the left image. If the fiber panel is mirroring the active equipment click on the right image. The link diagram will show the cables and patch cords entering the panel properly.
9: Choose up to 10 modules to configure your link, from left to right.

23: Loss Allowances.

Once completed, the bottom section will show the configured link with the modules you have selected. You will see the calculated Maximum Allowable Losses for two wavelengths: 850nm/1300nm for multimode fiber and 1310nm/1550nm for single-mode fiber. The FPC displays two sets of loss calculations if the configuration uses any non-ULL connections in the link. The top row shows the calculated losses for the selected configuration. The bottom row shows the attainable maximum losses if all non-ULL connections are replaced with their ULL equivalent connections. If only ULL modules are used a single set of results is shown. The results are not calculated by a simple sum of the typical losses for each connection. Rather, the algorithm uses an industry-approved statistical approach that takes into account standard deviation for each type of connection.
In order to request a Warranty Certificate from CommScope, installers should measure the actual optical losses of the installed links and these should be lower than the calculated maximum acceptable losses. On the right pane you can see the support for a broad variety of fiber applications. The icons to the left of the distance will indicate if the application is fully supported with the given length (and will show you the maximum distance); if the application is supported but the selected distance exceeds the limit; if the fiber type is not supported or if the selected configuration is not included in the SYSTIMAX performance specs (this is normally due to a mix of many types of connections or too many instances of the same connection).
Finally, clicking the blue button at the left side of the loss results enables you to copy the configuration, calculations and supported applications to the spreadsheet report and updates the handout sheet in the Excel book.

24: Loss Allowances.

When you exit the link configuration form, you can see the logged results in the first sheet of the Excel book. The upper row buttons allow you to return to the Calculator, send the results by email, clear the log sheet and show/hide the columns for applications support.

25: Loss Allowances.

Let's look at a few examples of fiber link configurations. In this first example, equipment with SC interface connections is connected to a panel with LC connectors. The trunk cable is spliced to the panel with LC pigtails. The trunk cable then feeds to a cross-connection patch area, converting from a LC panel to a SC panel. The trunk cable from this SC panel is terminated to an outlet with a Qwik SC, which is equivalent to a splice connection, and then connected to the end device with an SC to SC cord.

26: Loss Allowances.

Representing this link in the FPC, the left button is clicked to represent the equipment being patched to the first panel. The spliced LC connection icon is selected to represent the mated pair plus spliced pigtail at the first panel. The mated pair connection at the LC panel of the cross-connect is selected using the LC to LC icon. The other end of the cross-connect which is an SC connection is selected using the SC to SC icon. To complete the link, the spliced SC mated pair icon is selected to represent the Qwik SC connection interfacing with the SC patch cord.

27: Loss Allowances.

The result is that the configured link displays in the FPC as shown. Just visually check this is correct before continuing otherwise it will throw the calculations out.

28: Loss Allowances.

This second example is similar to the previous example, but now the trunk cables are terminated with MPO modules in the cross-connect area, and the cables are pre-terminated at the first panel rather than spliced.

Question answer:


31: Loss Allowances.

Example 3 here shows that the connections in this link are all Ultra Low Loss. The connection from the equipment to the first panel is an 8 fiber MPO. The trunk cable is terminated with 24 fiber MPO, and therefore connected to MPO24 to MPO8 modules in the panel. The cross-connect is a straight through 24 to 24 MPO connection and then the 24 fiber trunk cable is split back out to an 8 fiber MPO at the other end.

32: Loss Allowances.

Representing this link in the FPC, the left button is clicked to represent the equipment being patched to the first panel. The Ultra Low Loss MPO 24 '1 by 3' connection icon is selected to represent the mated pair at the first panel. The first mated pair connection at the cross-connect is selected using the MPO 24 to MPO 24 icon. The other end of the cross-connect is selected also using the MPO 24 to MPO 24 icon. To complete the link, the mated pair icon is selected to represent the MPO 24 '1 by 3' connection interfaced with the MPO 8 patch cord.

33: Loss Allowances.

The result is that the configured link displays in the FPC as shown. Remember to check it visually.

34: Loss Allowances.

In this final example, it shows how a link that has a TAP module is catered for in the FPC. The example uses 12 fiber MPO trunk connections throughout, and has a 70/30 TAP module in the cross-connect. The patch cords are all LC connections.

35: Loss Allowances.

Representing this link in the FPC, the left button is clicked to represent the equipment being patched to the first panel. The TAP button is checked, and the 70/30 selected. The total length and the length of the two 'monitored' links are inserted. The MPO 12 to LC connection icon is selected to represent the mated pair and module at the first panel. The connection at the LC panel of the cross-connect is selected also using the MPO to LC icon. The other end of the cross-connect which is the TAP connection, is selected using the TAP icon. To complete the link, the spliced MPO to LC icon is selected to represent the connection interface with the jumper to the equipment.

36: Loss Allowances.

The result is that the configured link displays in the FPC as shown. As you can see, this program makes calculations easy.

37: Link Loss Calculator & Fluke Versiv Linkware.

The CommScope fiber link loss calculator is being integrated into the Fluke testing platform so that when you test a SYSTIMAX fiber link, with the parameters set, the test results saved will be acceptable for warranty purposes. The calculator includes the latest low loss and ultra low loss specifications for both single-mode and multimode fiber.

38: Link Loss Calculator & Fluke Versiv Linkware.

The saved results, when combined with the Fluke's LinkWare software, allows them to be saved in the cloud as part of the project you are working on, at any time. LinkWare also allows you to edit, view, print, save or archive test results by job site, customer, campus or building and then download as required for your records or as submission to CommScope as part of the warranty process.

39: That Completes This Lesson.

In this part of the lesson, we will look at the key requirements for high density connectivity solutions in the data center.

2: The Characteristics of a Successful Data Center.

The characteristics of a successful data center in a competitive global market is lower operations costs, greater reliability and flexibility in service offerings and quicker deployment of new and upgraded services. These data centers use a great deal of fiber, the medium that meets both bandwidth and cost requirements. Just deploying fiber though is not enough. A successful fiber network also requires a well built infrastructure based on a strong fiber cable management system as this has a direct impact on network reliability, performance and cost.
The cable management system needs to be able to provide bend radius protection, cable routing paths, cable accessibility and physical protection of the fiber network because linked in with this is going to be network maintenance and operations, where the ability to reconfigure or expand the network, restore service and implement any new services is paramount. Having this type of infrastructure in place will ensure that the data center is at the top of a cost competitive marketplace.

3: Fundamental #1: Bend Radius Protection.

There are four critical elements of fiber cable management: bend radius protection, cable routing paths, cable access and physical protection. All four aspects directly affect the network's reliability, functionality and operational cost. Let's consider the first - bend radius protection.

4: Fundamental #1: Bend Radius Protection.

Cable raceways, fiber termination panels and distribution frames should be designed, installed and maintained so as to properly manage the minimum allowable bend radius for fiber cables and patch cords.

5: Bend Radius.

There are two basic types of bends in fiber, microbends and macrobends. As the names indicate, microbends are very small bends or deformities in the fiber, while macrobends are larger bends. The fiber's radius around bends impacts the fiber network's long-term reliability and performance. Simply put, fibers bent beyond the specified minimum bend diameters can break, causing service failures and increasing network operations costs.
Cable manufacturers, Internet service providers and others specify a minimum bend radius for fibers and fiber cables. The minimum bend radius will vary depending on the specific fiber cable however, in general, the minimum bend radius should not be less than ten times the outer diameter (OD) of the cable. Thus a 3 mm cable should not have any bends less than 30mm in radius.
Telcordia recommends a minimum 38 mm bend radius for 3 mm patch cords and this radius is for a fiber cable that is not under any load or tension. If a tensile load is applied to the cable, as in the weight of a cable in a long vertical run or a cable that is pulled tightly between two points, the minimum bend radius is increased, due to the added stress.
There are two reasons for maintaining minimum bend radius protection. Firstly, enhancing the fiber's long-term reliability, and secondly reducing signal attenuation. Bends with less than the specified minimum radius will exhibit a higher probability of long-term failure as the amount of stress put on the fiber grows. As the bend radius becomes even smaller, the stress and probability of failure increase. The other effect of minimum bend radius violations is more immediate as the amount of attenuation through a bend in a fiber increases, as the radius of the bend decreases.

6: Bend Radius.

The problems grow when more fibers are added to the system. As fibers are added on top of installed fibers, macrobends can be induced on the installed fibers if they are routed over an unprotected bend. A fiber that had been working fine for years can suddenly have an increased level of attenuation, as well as a potentially shorter service life.
Since any unprotected bends are a potential point of failure, the fiber cable management system should provide bend radius protection at all points where a fiber cable makes a bend. Having proper bend radius protection throughout the fiber network helps ensure the network's long-term reliability, thus helping maintain and grow the customer base. Reduced network down time due to fiber failures also reduces the operating cost of the network.

7: Bend Insensitive Style Fibers.

Bending of fiber has everyone talking these days. The idea that you can bend a fiber around a pencil without a dramatic increase in attenuation is a concept that has everyone considering new fiber applications and design possibilities. We have just discussed the minimum bend radius of patch cords being typically ten times the OD of the jacketed cable but the new breed of Bend Insensitive optical fiber has the potential to significantly reduce these minimum bend radius requirements to values as low as 0.6 inch (15 mm), depending on the cable configuration, without increasing attenuation. There are many names for optical fiber that can endure a tighter bend radius such as "bend insensitive," "bend resistant" or "bend optimized".

8: Does it Improve Performance?

Despite the improved bend radius of these new 'reduced bend radius' style fibers, in reality, bend radius is still a concern, but just not to the extent of regular fiber. There is still a mechanical limit on how tightly any optical fiber can be routed before the structural integrity of the glass is violated. The assumptions about improved performance are not accurate either, at least beyond the exceptional bend radius performance. In reality, the performance of reduced bend radius optical fiber, or any optical fiber depends upon many factors, not just bend radius properties.
By itself, reduced bend radius optical fiber does not offer improvements in attenuation. True, it bends more tightly without causing additional attenuation, yet laid out on a long, straight run next to a standard optical fiber, there is no difference in performance that can be attributed to the cables' construction. It is inaccurate to believe that reduced bend radius optical fiber is the 'end-all' solution when there are many other factors that actually determine optical fiber link performance, including durability, connector pull-off resistance and connector performance.
When it comes to an optical fiber network, success may be measured in one or many ways. These include maximum system uptime, minimum operational and material costs, or no lost revenue due to outages. Achieving these goals requires a complete cable management system that includes cable routing paths, cable and connector access, physical protection and of course, bend radius protection.

9: Fundamental #2: Easy and Intuitive Cable Routing.

The second aspect of fiber cable management is cable routing paths.

10: Fundamental #2: Easy and Intuitive Cable Routing.

Racks and cabinets, fiber termination panels and distribution frames should be designed, installed and maintained so as to provide easy and intuitive cable routing and proper slack storage.

11: Cable Routing Paths.

This aspect is related to bend radius, as improper routing of fibers by technicians is one of the major causes of bend radius violations. Routing paths should be clearly defined and easy to follow, so that the technician has no other option than to route the cables properly. Well-defined routing paths reduce the training time required for technicians, increase the uniformity of the work done and ensure that the bend radius requirements are maintained at all points, improving network reliability. Additionally, having defined routing paths makes accessing and tracing individual fibers easier, quicker and safer, reducing the time required for reconfigurations.
This has a direct effect on network operating costs and the time required to turn-up or restore service. Alternatively, leaving cable routing to the technician's imagination leads to an inconsistently routed, difficult-to-manage fiber network. Improper cable routing also causes increased congestion in the termination panel and the cableways, increasing the possibility of bend radius violations and long-term failure.

12: Fundamental #3: Connector Accessibility.

The third element of fiber cable management is the accessibility of the installed fibers.

13: Fundamental #3: Connector Accessibility.

Fiber termination panels and distribution frames should be designed, installed and maintained so as to provide easy connector and mating adapter access.

14: Fundamental #3: Connector Accessibility.

Accessibility is most critical during network reconfiguration operations and directly impacts operation costs and network reliability. Allowing easy access to installed fibers is critical in maintaining proper bend radius protection and should also ensure that any fiber can be installed or removed without inducing a macrobend on an adjacent fiber. Good accessibility of the fibers in the fiber cable management system can mean the difference between a network reconfiguration time of less than 20 minutes and up to 90 minutes per fiber.

15: Fundamental #4: Physical Protection of the Fiber.

The fourth element of fiber cable management is the physical protection of the installed fibers and equipment. All fibers should be protected throughout the network from accidental damage by technicians.

16: Fundamental #4: Physical Protection of the Fiber.

Cable raceways, racks and cabinets, fiber termination panels and distribution frames should be designed, installed and maintained so as to provide physical protection for fiber cables, connectors and patch cords.

17: Physical Fiber Protection.

Fibers routed between pieces of equipment without proper protection are susceptible to damage, which can critically affect network reliability. The fiber cable management system should therefore ensure that every fiber is protected from physical damage along the entire route.

18: ODF Slack Storage.

Most Optical Distribution Frame (ODF) systems, encounter cable management problems in the storage of excess fiber cable. Since most data center fiber solutions are factory-terminated to a patch cord of a predetermined length, there is always some excess fiber remaining after the physical connections have been made. At some point during the life of the fiber network, it is likely that virtually every fiber circuit will need to be reconfigured. For most circuits, the duration between reconfigurations will be a long time, perhaps three to five years. During this time, these fibers need to be properly protected to ensure they are not damaged during day-to-day network operations. As the fiber's physical length and its potential exposure to damage and bend radius violations is greatest here, the slack storage system is perhaps the most critical element in terms of network reliability and re-configurability. It needs to provide flexible storage capacities, permanent bend radius protection and easy access to individual fibers.
Slack storage systems come in many styles and configurations that can involve coiling or wrapping fibers in open troughs or vertical cableways, which can increase the probability of bend radius violations and can make fiber access more difficult and time-consuming. The accessibility and thus the amount of time required to reconfigure the network, is optimal in a system that maintains a continuous non-coiled or twisted routing of fibers.

19: Dedicated Cable Raceway System.

As the fibers are routed from the ODF to the equipment, they need to be protected. In order to provide proper protection and ensure future growth and reconfiguration capabilities, all fibers routed between the ODF and the equipment should be placed in a dedicated cable raceway system. This system is generally located at the lower level of the auxiliary framing/ladder racking structure. Locating the raceway system there, makes access for installing and routing fibers easier. As the system is in an area of the office in which technician activities are common, the cable raceway system needs to be durable and robust enough to handle day-to-day activities.
For example, technicians installing copper or power cables on the ladder racking can come into contact with the system. If the system is not robust enough to withstand a technician accidentally putting his weight on it, the integrity of all the fibers in the system is in jeopardy. A durable, properly configured raceway system with suitable cable management, especially bend radius protection, helps improve network reliability and makes network installation and reconfiguration faster and more uniform.

20: FiberGuide.

CommScope's FiberGuide Raceway System is an example of hassle-free, easy to install, flexible and customizable, comprehensive protection solution for cabling networks in multi-tenant and enterprise data center environments. It is a modular system designed to provide a dedicated pathway for critical network segments including fiber and copper cabling.

21: Capacity Requirements, Current & Future.

The total number of patch cords in the system must be calculated to determine which size FiberGuide system is required. The maximum number of fibers that the FiberGuide system can handle depends on the patch cord jacketing and the capacity as outlined here in the chart. Telecordia recommend limiting jumper 'pileup' to 50mm (2 inch) so all new raceway installations should be designed to this specification. Consideration should also be given to perhaps allowing spare future capacity too.

22: Current & Future Layout.

The horizontal raceway must be designed to reduce the opportunity for congestion and bottlenecks so diverse routing paths should also be considered for added protection.

To do this a current floor plan that documents existing infrastructure and outlines future growth will be required. Both the placement of frames on the floor and the vertical location of overhead racking must be taken into account. Remember overhead racking can provide points of attachment for FiberGuide components, or could be a source of interference that must be designed around.

23: Obstacles.

Physical obstacles that cannot be moved will affect the FiberGuide design. This will include such things as columns, space constraints, intra-facility cable drops, or existing overhead racking. A walk-through site survey is recommended to identify obstacles but fortunately FiberGuide has a full range of fittings to change direction, plane, level and angle as required.

24: Obstacles.

For optimal cooling efficiencies, keep in mind the FiberGuide placement can affect air flow. Often when placed above the rows, there is less interference with hot/cold aisles which allows for free air movement.

25: Support Locations & Styles.

Attachment points for FiberGuide components include ladder racking, ceiling support, auxiliary racking and bay top support. There is a variety of mounting hardware to provide great flexibility. For optimal design, the placement of the fiber frame, the FiberGuide components and the attachment point should be determined in tandem. Different attachment points (eg. bay top versus ladder racking) may dictate the use of one downspout option over another. If overhead racking is the chosen attachment point, positioning the frame correctly in relation to auxiliary supports or ladder racking is critical to optimal placement for fiber drops.

26: Frame Styles.

Different frame styles have different footprints and exit points for the patch cords so the full range of FiberGuide exit options and attachments, maximizes the flexibility to design the correct fitment to meet most applications. A standard downspout works well for fiber distribution frames.

'Island T's' were designed specifically for the CommScope NGF system. These downspouts manage the large fiber drops and route the patch cords correctly for entry into the storage bays. The extended downspout is an ideal drop option when mounting FiberGuide above racks or cabinets. Choosing the best option is probably the most difficult decision.

27: Vertical Drop Options.

If overhead racking is the chosen attachment point, positioning the frame correctly in relation to auxiliary supports or ladder racking is critical to optimal placement for fiber drops. A variety of mounting hardware provides the flexibility to mount FiberGuide wherever needed.

28: Cable Raceway Congestion.

Cable congestion is just like traffic congestion. Put too many cars at one time onto a small road and you have traffic problems. It becomes difficult to move from one point to another, and the probability of having an accident increases. The same basic rules apply to fiber congestion in an ODF's raceway system so planning in advance the quantities and the routing is critical. If too many fibers are routed into a single trough, accessing an individual fiber becomes very difficult, and the probability of damaging a fiber increases. This can lead to decreased network reliability and so an increase in the time it takes to reconfigure the network.

29: Ideal Data Center Infrastructure.

Commscope's end-to-end support for the DC as well as FiberGuide Raceway includes fiber entrance cabinets, distribution frames, patch panels and fiber or copper patch cords for interconnects and cross-connects between equipment and applications. The ODF system put into a DC should be capable of handling the future requirements of the network. The addition of any new panels, whether for splicing, termination, storage or other functions should not cause any interference with or movement of the installed fibers. This ensures that network reliability is maintained and also allows new services to be implemented quickly and cost-effectively. This ability to add equipment as needed allows the ODF (Optical Distribution Frame) to grow as the network requirements grow, thus reducing the initial installation cost of the network while reducing the risk of network failure.
CommScope has high-density ODFs to accommodate very high numbers of terminations in increasingly smaller footprints. While high termination density requires less floor space, strong consideration needs to be given to the overall cost of such increased density. A higher-density ODF does not necessarily correspond to a higher fiber count potential in the DC. The focus needs to be on having a system with strong cable management features that is flexible enough to accommodate future growth, while allowing for easy access to the installed fiber network.

30: ODF: The Fundamental Building Blocks.

Any decent ODF solutions should always consist of 6 fundamental building blocks. If one of them is absent or incomplete the ODF solution is incomplete and therefore the customer will struggle to find a good solution. The six blocks are:
1) A SPECIFIC frame solution to house connectivity blocks and offer superior cable and patch cord management;
2) A housing to facilitate the connectivity (adapters). Note the housing is referred in several terminologies: shelf, panel, block, chassis, or subrack etc;
3) Adapters or adapter packs;
4) Design, component and building blocks to enable pre-cabled solutions: easy to built in-factory but also easily packed, shipped, unpacked and installed on site;
5) Value Added Modules fitting in the same footprint as the adapters to support filters, splitters, monitoring devices, etc.
6) On-frame splicing solutions, as not all customers do off-frame splicing.

31: ODF: The Fundamental Building Blocks.

The CommScope NGF is a frame with integrated spools for enabling 'any to any' connection within the frame, with 1 single 6m length patch cord. For connection to any additional frame, you just add 1 meter (7 for the next, 8 for the second next, etc.). The NGF frame has an integrated trough system requiring access to the back, therefore frames cannot be placed back to back. NGF blocks exist in 3 variants:
1) Adapter only (not recommended due to difficult to fiber up in the field);
2) MPO on the back (192 and 288 version have improved MPO access pointing to the back into the troughs instead of up);
3) Pre-terminated with a stub cable of 10 - 40m. VAM (Value Added Modules) are available designed to fit in the same footprint as the sliding adapter pack. Lastly, on-frame splicing solutions are available with a combination block, however this means significant reduction of the frame density.

32: NG4 Access.

Similar to the NGF, the NG4 frame has a specific frame with an integrated spool system enabling 'any to any' connection within the frame with a single 6m patch cord. The spool diameter is smaller than the NGF and therefore NG4 works with G657A2 (bend insensitive style) fiber only (15mm bend radius).

The NG4 has no blocks but has a chassis with the following benefits: A blade system allowing it to integrate several types of connectivity from adapter packs, to MPO/LC modules and VAMs. It has much higher levels of modularity than the NGF allowing the customer to build as they grow and it shares the same style back and front access with sliding blades. Each chassis can hold up to 576 LC or 288 SC connections, with the whole frame managing up to 3,456 LC connections and has options for on-frame splicing if required. Any patch cord slack storage is integrated into the left side of the frame. Modular building blocks include: SC or LC adapter packs, cabled modules attached to Rapid Reel panels, MPO to LC or SC modules, Value Added Modules (CWDM/DWDM), and splice trays.

33: NG4access Building Blocks.

The NG4access has building blocks that make up the platform. The building blocks include the frame and Universal Chassis. This is designed for easy technician access. The chassis features the same user interface on the front and back side of the unit and while during service turn-up and maintenance, the access trays pull open and lock in place for easy access to the connectors. Pivot points on the access trays prevent the fiber from moving while being opened or closed, which helps prevent any unwanted disturbances to live services.
The adapter packs are designed to accept a variety of connector types including single-mode, multimode, angled and ultra polished connectors. The staggered adapter pack design helps installers access connectors without pinching or moving adjacent ones. This eliminates the need for installers to use extraction tools and helps clearly identify individual fiber ports. A specially designed latch window on the rear of the adapter pack allows easy identification of the connector type on the opposite side of the unit. As a result, technicians will always know the connector type installed in the adapter, no matter if they are working on the front or rear side of the frame.

Pre-terminated modules can be added to a Universal Chassis and spliced into a panel in another cabinet. The splice chassis option on the rear of the frame allows for on-frame splicing as well.

34: FACT.

In comparison to NGF and NG4access, FACT is a 'full front access' ODF solution designed for use with the legacy FIST-GR3 frame that can be easily assembled on site. The building blocks of the FACT ODF are its splicing and/or patching elements.

Each element offers 48 LC connections and measures 30.95 mm tall, 30-percent less than the standard HU (44.45mm). FACT elements can be deployed individually or similar elements can be combined into high-density modules. Four elements snap together to create one 3HU module that can support 192 LC connections. Six elements combine into 288 ports that can fit in a 5HU slot. Each FACT element features two hinged trays providing full front access to both sides of all connections and clear visibility of all ports. The element trays secure the fibers in place during manipulation to ensure optical performance and eliminate transient signal loss. Exiting patch cords are routed over spools in the back of the frame to minimize bending.

All FACT elements, with the exception of Splice-Only solutions, can be custom configured with a variety of adapters, splicing and passive optical components.

Add Standard Connectors (SC) and Small Form Connectors (LC), with Ultra-Polished Contacts (UPC) and Angled Physical Contacts (APC), to support a wide range of datacom and telecom applications, including G-PON, E-PON and Dense Wavelength Division Multiplexing (DWDM). Backplates are available in kits that include the backplate, U-shaped mounting brackets and all necessary hardware. These are available in 1, 2 or 4 element sizes or an extra large 28 element backframe.

35: That Completes This Lesson.