Tia 942 pdf download

Data centers typically utilize patch cords that are longer than 5 m 16 ft. In data centers that use longer patch cords, the maximum backbone cabling distances shall be reduced accordingly to ensure that the maximum channel lengths are not exceeded.

See subclause 6. NOTES 1 The 90 m ft distance limitation assumes uninterrupted cabling runs between cross-connects that serve equipment i.

Depending upon the characteristics of the individual application, choices with respect to transmission media should be made. Each recognized cable has individual characteristics that make it suitable for a myriad of applications and situations. A single cable may not satisfy all end user requirements.

It may be necessary to use more than one medium in the backbone cabling. In those instances, the different media shall use the same facility architecture with the same location for cross-connects, mechanical terminations, interbuilding entrance rooms, etc.

Centralized optical fiber cabling is designed as an alternative to the optical cross-connection located in the horizontal distribution area when deploying recognized optical fiber cable in the horizontal in support of centralized electronics. Centralized cabling provides connections from equipment distribution areas to centralized cross-connects by allowing the use of pull-through cables, an interconnect, or splice in the horizontal distribution area.

Centralized cabling implementations shall be located within the same building as the equipment distribution areas served. The administration of moves, adds and changes shall be performed at the centralized cross-connect. Centralized cabling design shall allow for migration in part or in total of the pull-through, interconnect, or splice implementation to a cross-connection implementation.

Sufficient space shall be left in the horizontal distribution area to allow for the addition of patch panels needed for the migration of the pull-through, interconnect, or splice to a cross-connection.

Sufficient cable slack shall exist in the horizontal distribution area to allow movement of the cables when migrating to a cross-connection. Slack may be stored as cable or unjacketed fiber buffered or coated. Slack storage shall provide bend radius control so that cable and fiber bend radius limitations are not violated.

Fiber slack shall be stored in protective enclosures. The layout of the termination hardware should accommodate modular growth in an orderly manner.

The intrabuilding backbone fiber count should be sized to deliver present and future applications to the maximum equipment distribution areas density within the area served by the horizontal distribution area. Generally, two fibers are required for each application delivered to an equipment distribution area. In addition, horizontal distribution area splice and interconnect hardware shall be labeled with unique identifiers on each termination position. Field color-coding is not used at the interconnect or splice.

The centralized cross-connect termination positions in the main distribution area shall be labeled as a blue field. The blue field shall move to the horizontal distribution area for each circuit that is converted to a cross-connection in the horizontal distribution area. Centralized cabling shall be implemented to ensure the correct fiber polarity as specified in subclause Any maintenance holes, pull boxes, and splice boxes shall be equipped with a lock.

Telecommunications entrance cabling for data centers should not be routed through a common equipment room CER. Any maintenance holes on building property or under control of the data center owner should be locked and monitored by the data center security system using a camera, remote alarm or both.

Access to pull boxes for data center cabling entrance cabling or cabling between portions of the data center that are located in public spaces or shared tenant spaces should be controlled. The pull boxes should also be monitored by the data center security system using a camera, remote alarm or both.

Any splice boxes for data center cabling that are located in public spaces or shared tenant spaces should be locked and monitored by the data center security system using a camera, remote alarm or both. Entrance to utility tunnels used for telecommunications entrance rooms and other data center cabling should be locked. If the tunnels are used by multiple tenants or cannot be locked, telecommunications cabling for data centers shall be in rigid conduit or other secure pathway.

This separation is specified to accommodate the wide variety of equipment that may be present in a data center, but are not found in a typical office environment or telecommunications room. Electrical codes may require a barrier or greater separation than specified in table 2.

Refer to NFPA 70, article or applicable electrical code for additional information. However, these distances can apply to unshielded power cables if either the power cables or data cables are installed in bonded and grounded metal tray. The side or the bottom of the metal tray shall separate the power cables from the twisted-pair cables, this separation surface should be solid metal.

The shielding shall completely surround the cable except at the receptacle and shall be properly bonded and grounded in accordance with the applicable electrical codes. There are no requirements for separation of power and telecommunications cabling crossing at right angles, except the separation requirements mandated by applicable electrical codes.

No separation distance is required when either the data cables or the power cables are enclosed in metallic raceway or conduit that meets the following requirements: - the metallic raceway or conduit shall completely enclose the cables and be continuous; - the metallic raceway or conduit shall be properly bonded and grounded in accordance with the applicable electrical codes; - the raceway or conduit shall be at least 1 mm 0.

Branch circuits in data centers should be in watertight flexible metal conduit. Feeder circuits to power distribution units and panels should be installed in solid metal conduit. If the feeder circuits are not in solid metal conduit, they should be in watertight flexible metal conduit.

In data centers that use overhead cable trays, the normal separation distances provided by standard practices provides adequate separation.

This provides adequate separation if the electrical cables are shielded or if the power cable tray meets the specifications of the subclause 7. Provide horizontal separation by allocating different rows of tiles in the main aisles for power and telecommunications cabling, with the power and telecommunications cables as far apart from each other as possible.

Additionally, provide vertical separation by placing the telecommunications cabling in cable trays or baskets as far above the power cables as possible, preferably with the top of the cable tray or basket 20 mm 0. Physical barriers between the two types of cables are not necessary. Where it is not practical to separate fiber and copper cables, fiber cables should be on top of copper cables. Aerial entrance pathways for telecommunications service entrance pathways are not recommended because of their vulnerability due to physical exposure.

The entrance pathways should also have adequate capacity to handle growth and additional access providers. Each access provider should have at least one mm 4 in trade size conduit at each entrance point. Additional conduits may be required for campus. Conduits used for optical fiber entrance cables should have three innerducts [two 38 mm 1. Cables shall be terminated on at least one end in the main distribution area or a horizontal distribution area, or shall be removed.

For additional information on rack and cabinet installation with access flooring systems, refer to subclause 5. Under floor cable trays may be installed in multiple layers to provide additional capacity. Metallic cable tray shall be bonded to the data center grounding infrastructure. The cable tray should have a maximum depth of mm 6 in.

Under-floor cable tray routing should be coordinated with other under floor systems during the planning stages of the building. Access floors for data centers should use a bolted stringer understructure, as they are more stable over time than stringerless systems. Additionally, access floor stringers should be 1.

Pedestals should be bolted to the subfloor for added stability. If the edging or grommets are higher than the surface of the access floor, they shall be installed as not to interfere with placement of racks and cabinets. The edging or grommets shall not be placed where the racks and cabinets normally contact the surface of the access floor. In the case of floor discharge HVAC systems, floor tile cuts should be limited in both size and quantity to ensure proper airflow.

It is recommended that the HVAC system be properly balanced once all equipment racks, cabinets, etc are in-place. The HVAC system should be re-balanced with the addition of floor cuts, equipment racks, cabinets, etc. Consult the AHJ before deciding on the type of cable to use under access floors. NOTE — This standard references applicable requirements relating to fire, health and safety.

In addition, consider the selection of cable types and fire suppression practices that minimize damage in the event of fire. Overhead cable trays may be installed in several layers to provide additional capacity. Typical installations include two or three layers of cable trays, one for power cables and one or two for telecommunications cabling. One of the cable tray layers typically has brackets on one side that hold the data center grounding infrastructure.

These overhead cable trays are often supplemented by a duct or tray system for fiber patch cables. The fiber duct or tray may be secured to the same hanging rods used to support the cable trays. Cables shall not be left abandoned in overhead cable trays. In aisles and other common spaces in internet date centers, co-location facilities, and other shared tenant data centers, overhead cable trays should have solid bottoms or be placed at least 2. The maximum recommended depth of any cable tray is mm 6 in.

If all racks and cabinets are of uniform height, the cable trays may be attached to the top of racks and cabinets, but this is not a recommended practice because suspended cable trays provide more flexibility for supporting cabinets and racks of various heights, and provide more flexibility for adding and removing cabinets and racks.

Typical cable tray types for overhead cable installation include telco-type cable ladders, center spine cable tray, or wire basket cable tray.

If required by prevailing code, adjacent sections of cable tray shall be bonded together and grounded per AHJ, and shall be listed by a nationally recognized testing laboratory NRTL for this purpose. The cable tray system should be bonded to the data center grounding infrastructure.

Lighting fixtures and sprinkler heads should be placed between cable trays, not directly above cable trays. This Standard includes four tiers relating to various levels of availability of the data center facility infrastructure. Information on infrastructure tiers can be found in annex G.

The Figure 10 illustrates various redundant telecommunications infrastructure components that can be added to the basic infrastructure. The reliability of the communications infrastructure can be increased by providing redundant cross-connect areas and pathways that are physically separated.

It is common for data centers to have multiple access providers providing services, redundant routers, redundant core distribution and edge switches. Although this network topology provides a certain level of redundancy, the duplication in services and hardware alone does not ensure that single points of failure have been eliminated. These pathways will include customer-owned maintenance holes where the access provider conduits do not terminate at the building wall.

The maintenance holes and entrance pathways should be on opposite sides of the building and be at least 20 m 66 ft apart. In such a configuration, each access provider is typically requested to install two entrance cables, one to the primary entrance room through the primary maintenance hole, and one to the secondary entrance room through the secondary maintenance hole. Conduits from the primary maintenance hole to the secondary entrance room and from the secondary maintenance hole to the primary maintenance hole provide flexibility, but are not required.

In data centers with two entrance rooms, conduits may be installed between the two entrance rooms to provide a direct path for access provider cabling between these two rooms for example, to complete a SONET or SDH ring. Utilizing multiple access providers ensures that service continues in the event of a access provider-wide outage or access provider financial failure that impacts service.

Utilizing multiple access providers alone does not ensure continuity of service, because access providers often share space in central offices and share rights-of-way. The customer should ensure that its services are provisioned from different access provider central offices and the pathways to these central offices are diversely routed.

These diversely routed pathways should be physically separated by at least 20 m 66 ft at all points along their routes. Multiple entrance rooms improve redundancy, but complicate administration. Care should be taken to distribute circuits between entrance rooms.

Access providers should install circuit provisioning equipment in both entrance rooms so that circuits of all required types can be provisioned from either room. The access provider provisioning equipment in one entrance room should not be subsidiary to the equipment in the other entrance room. The access provider equipment in each entrance room should be able to operate in the event of a failure in the other entrance room. The two entrance rooms should be at least 20 m 66 ft apart and be in separated fire protection zones.

The two entrance rooms should not share power distribution units or air conditioning equipment. Core routers and switches should be distributed between the main distribution area and secondary distribution area.

Circuits should also be distributed between the two spaces. A secondary distribution area may not make sense if the computer room is one continuous space, as a fire in one portion of the data center will likely require that the entire data center be shut down. Redundant backbone cabling may be provided in several ways depending on the degree of protection desired. Backbone cabling between two spaces, for example, a horizontal distribution area and a main distribution area, can be provided by running two cables between these spaces, preferably along different routes.

If the data center has both a main distribution area and a secondary distribution area, redundant backbone cabling to the horizontal distribution area is not necessary, though the routing of cables to the main distribution area and secondary distribution area should follow different routes.

Some degree of redundancy can also be provided by installing backbone cabling between horizontal distribution areas. If the backbone cabling from the main distribution area to horizontal distribution area is damaged, connections can be patched through another horizontal distribution area.

Care should be taken not to exceed maximum horizontal cable lengths when selecting paths. Critical systems can be supported by two different horizontal distribution areas as long as maximum cable length restrictions are not exceeded. This degree of redundancy may not provide much more protection than diversely routing the horizontal cabling if the two horizontal distribution areas are in the same fire protection zone.

The maximum supportable distances proposed in this annex are application and media dependent. The use of ohm coaxial type cable is based on the provisioning of T-3 circuits from the access provider to the end equipment area. The use of current These calculations assume that there is no customer DSX panel between the access provider demarcation point which may be a DSX and the end equipment. The access provider DSX panel is not counted in determining maximum circuit lengths. Repeaters can be used to extend circuits beyond the lengths specified above.

These circuit distances should be adjusted for attenuation losses caused by a DSX panel between the access provider demarcation point which may be a DSX panel and the end equipment.

The following table 4 provides the reduction caused by DSX panels in maximum circuit distances for T-1, T-3, E-1, and E-3 circuits over the recognized media type.

The following table 5 provides the reduction in maximum circuit distances for T-1, T-3, E-1, and E-3 circuits over the recognized media type. Maximum circuit lengths for the typical data center configuration are in the following table 6. These maximum circuit lengths include backbone cabling, horizontal cabling, and all patch cords or jumpers between the access provider demarcation point and the end equipment.

The maximum backbone cabling distance is the sum of the length of cabling from the entrance room to the main distribution area and from the main distribution area to the horizontal distribution area. Due to the very short distances permitted by category 3 UTP cabling and type coaxial cable for T-1, T-3, E-1, and E-3 circuits, category 3 UTP and type coaxial cables are not recommended for supporting these types of circuits.

Backbone cabling distances can be increased by limiting the locations where T-1, E-1, T-3, and E-3 circuits will be located for example only in the main distribution area or locations served by horizontal cabling terminated in the main distribution area. Other options include provisioning circuits from equipment located in the main distribution area or horizontal distribution area.

Recommended maximum distances over shielded twisted-pair cables are one half of the distances permitted over unshielded twisted-pair cables. Due to the increased data rate, fiber effects, such as dispersion, become a factor in the achievable distances and numbers of connectors used in fiber optic link designs. This leaves the network designer with new decisions and trade-offs that they must understand and overcome.

The only exception to these length restrictions should be in the case of ohm coaxial cables, for DS-3 patching, the maximum length should be 5 m Separate patching bays for copper-pair cables, coaxial cables, and optical fiber cables simplify management and serves to minimize the size of each type of patching bay.

Arrange patching bays and equipment in close proximity to minimize patch cord lengths. Consider installing category 6 twisted-pair cabling for all copper-pair cabling from the MC to the intermediate cross-connects ICs and HCs, as this will provide maximum flexibility for supporting a wide variety of applications. The type of terminations in the MC IDC connecting hardware or patch panels depends on the desired density and where the conversion from 1- and 2-pair access provider cabling to 4-pair computer room structured cabling occurs: - if the conversion from 1- and 2-pair access provider cabling occurs in the entrance room, then copper-pair cable terminations in the MC are typically on patch panels.

This is the recommended configuration; - if the conversion from 1- and 2-pair access provider cabling occurs in the MC, then copper- pair cable terminations in the MC should be on IDC connecting hardware. All coaxial cabling should be type coaxial cable. Termination of coaxial cables should be on patch panels with ohm BNC connectors.

Termination of fiber cables should be on fiber patch panels. Separate patching bays for copper-pair cables, coaxial cables, and optical fiber cables simplify management and minimize the size of each type of patching bay. The use of a single type of cable simplifies management and improves flexibility to support new applications.

Consider installing only one type of twisted-pair cable for horizontal cabling, for example all category 5e or all category 6 UTP , rather than installing different types of twisted-pair cables for different applications.

If individual telecommunications outlets are located on the same equipment rack or cabinet as the equipment served in lieu of a ZDA, equipment cord lengths should be limited to 5 m 16 ft. If cable lengths can be accurately pre-calculated, pre-terminated multi-fiber ribbon assemblies can reduce installation time. In these cases, consideration of the effects of additional connections should be considered to ensure overall fiber system performance. High data-rate end equipment may accommodate multi-fiber connectors directly.

Most data centers will require at least two letters and two numeric digits to identify every mm x mm or 2 ft x 2 ft floor tile. For an example, see figure In computer rooms with access floors, label cabinets and racks using the data center grid. Each rack and cabinet should have a unique identifier based on floor tile coordinates. If cabinets rest on more than one tile, the grid location for the cabinets can be determined by using the same corner on every cabinet e.

The cabinet or rack ID should consist of one or more letters followed by one or more numbers. So the cabinet whose front right corner is at tile AJ05 will be named AJ For example, 3AJ05 for the cabinet whose front right corner is at tile AJ05 on the 3rd floor of the data center. In figure 12, the Sample Cabinet is located at AJ Horizontal wire management panels do not count when determining patch panel position. If a rack has more than 26 panels, then two characters will be required to identify the patch panel.

See figure 13 for typical copper patch panel designation. For copper patch panels, two to three numeric characters.

Consider color-coding patch cables by application and type. Ideally, all access providers provide demarcation for their circuits in the same location rather than in their own racks. This simplifies cross-connects and management of circuits.

The centralized location for demarcation to all access providers is often called meet-me areas or meet-me racks. Cabling from the computer room to the entrance room should terminate in the demarcation areas. While service providers may prefer a specific type of IDC connecting hardware e. Cabling from the low-speed circuit demarcation area to the main distribution area should be terminated on IDC connecting hardware near the access provider IDC connecting hardware.

Circuits from access providers are terminated either in one or two pairs on the access provider IDC connecting hardware.

Different circuits have different termination sequences, as illustrated in figure 16 and figure Each 4-pair cable should be terminated in an eight-position modular jack at the work area. The access provider and customer IDC connecting hardware can be mounted on a plywood backboard, frame, rack, or cabinet. Patch panels from multiple access providers and the customer may occupy the same rack. For example, in the United States and Canada, access providers typically use DSX-1 patch panels that fit mm 23 in racks.

Thus, the DS-1 demarcation area should use one or more mm 23 in racks for access provider DS-1 patch panels. These same racks or adjacent mm 19 in racks can accommodate patch panels for cabling to the main distribution area. The DSX-1 patch panels may require power for indicator lights. Thus, racks supporting access provider DSX-1 patch panels should, at minimum have one 20A V circuit and a multi-outlet power strip.

Allocate rack space for access provider and customer patch panels including growth. Access providers may require rack space for rectifiers to power DSX-1 patch panels. These IDC connecting hardware can be placed on the same frame, backboard, rack, or cabinet as the IDC connecting hardware for low-speed circuits. A single 4-pair cable can accommodate one T1 transmit and receive pair. When multiple T1 signals are placed over multi-pair unshielded twisted-pair cable, the transmitted signals should be placed in one cable and the receive signals placed in a separate cable.

If the data center support staff has the test equipment and knowledge to troubleshoot T-1 circuits, the DS-1 demarcation area can use DSX-1 panels to terminate T-1 cabling to the main distribution area.

The IDC connecting hardware, modular jack patch panels, or DSX-1 panels for cabling to the main distribution area can be on the same or separate racks, frames, or cabinets as the ones used for access provider DSX-1 patch panels. If they are separate, they should be adjacent to the racks assigned to the access providers. The customer data center owner may decide to provide its own multiplexers M13 or similar multiplexer to demultiplex access provider T-3 circuits to individual T-1 circuits.

T-1 circuits from a customer-provided multiplexer should not be terminated in the T-1 demarcation area. The DSX-3 patch panels may require power for indicator lights. Thus, racks supporting access provider DSX-3 patch panels should, at minimum have one 20A V circuit and a multi-outlet power strip. Browse top new releases.

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