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Significant changes in data storage applications, data storage equipment, and storage area networks (SAN), have altered the telecommunication infrastructure requirements for the data center’s and computer rooms. Mainframes and their support peripherals are being supplanted by high performance servers interconnected with gigabit speed data links. The decentralization of computing resources from large mainframes to distributed server clusters has significantly impacted the infrastructure design for data center’s and computer rooms.
Published in early 2005, the Telecommunications Industry Association (TIA) has delivered TIA-942 the “Telecommunications Infrastructure Standard for Data Centers". The primary purpose of the standard is to provide a comprehensive understanding of the data center design including the facility planning, the cabling system, and the network design.
In parallel and subsequent to the development of TIA-942, the IEEE 802.3 Ethernet working group published two twisted-pair copper standards, 1000 Mb/s Ethernet designated 1000BASE-T and 10 Gb/s Ethernet (10 GbE) designated 10GBASE-T, both standards are targeted at meeting the increasing bandwidth requirements for data center applications.
This white paper will discuss the TIA-942 Data Center standard with emphasis on data center cabling and 10GBASE-T twisted-pair Ethernet data center applications.
Data Center Cabling: Targeted at bridging the information gap between the design and construction phases of a data center, the TIA-942 standard takes a multidisciplinary approach to the document content and structure facilitating coordination and cooperation between the architect, building engineer, and the telecommunications engineer. A key element of the standard is embodied in the data center cabling recommendations.
The data center cabling system includes the following elements:
- Horizontal cabling
- Backbone cabling
- Entrance cross-connect (EC) in the entrance room or main distribution area (if the entrance room is consolidated into the main distribution area).
- Main cross-connect (MC) in the main distribution area
- Horizontal cross-connect (HC) in the horizontal distribution area, telecommunications room, or main distribution area.
- Zone outlet (ZO) or consolidation point (CP) in the zone distribution area
- Outlet in the equipment distribution area
Horizontal cabling is the portion of the telecommunications cabling system that extends from the outlet in the equipment distribution area or zone outlet in the zone distribution area to the horizontal cross-connect in either the horizontal distribution area or main distribution area. Horizontal cabling may include an optional consolidation point in the zone distribution area.
Backbone cabling provides connections between the main distribution area, the horizontal distribution areas, telecommunications rooms, and entrance rooms in the data center cabling system.
Cabling Topology The topology of the data center horizontal cabling and backbone cabling is a star topology (Figure 1).
Horizontal cables are connected to a horizontal cross-connect in either a horizontal distribution area or main distribution area.
Backbone cabling uses a hierarchical star topology where each horizontal crossconnect in the horizontal distribution area is cabled directly to a main crossconnect in the main distribution area. Only one hierarchical level of cross-connect in the backbone cabling are allowed (there are no intermediate cross-connects within the data center cabling architecture).
Cabling Media: The standard recognizes multiple media types to support a wide variety of applications, but it recommends that the highest capacity cabling media be used for new installations to maximize the flexibility and useful life of the data center cabling infrastructure.
The recognized media are:
- 100-ohm twisted-pair cable (ANSI/TIA/EIA-568-B.2), category 6 is recommended (ANSI/TIA/EIA-568-B.2-1) or Class E/Category 6 as specified in ISO/IEC 11801;
- multimode optical fiber cable, either 62.5/125 micron or 50/125 micron (ANSI/TIA/EIA-568- B.3), 50/125 micron 850 nm laser optimized multimode fiber is recommended (ANSI/TIA-568- 16 B.3-1) or as specified in ISO/IEC 11801;
- singlemode optical fiber cable (ANSI/TIA/EIA-568-B.3) or as specified in ISO/IEC 11801;
- 75-ohm (734 and 735 type) coaxial cable (Telcordia Technologies GR-139- CORE) and coaxial connectors (ANSI T1.404). These cables and connectors are recommended to support T-3, E-1, and E-3 circuits.
10GBASE-T: TIA-942 data center applications: 10 GbE can be seamlessly deployed over twisted-pair copper data center cabling offering many advantages over alternative media types. The RJ-45 connector provides a single user interface enabling plug-and-play connectivity from active equipment to the patch panels located in each distribution area.
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