Additional characterization of the requirements specified in TIA-568-C.2 is necessary to ensure support of the 10GBASE-T application with limited implementations of category 6 cabling.

TSB-155-A “Guidelines for the Assessment and Mitigation of Installed Category 6 Cabling to Support 10GBASE-T” was developed by the TIA TR-42.7 Copper Cabling Subcommittee and published in March, 2010.  This Telecommunications Systems Bulletin identifies the additional performance headroom, as well as applicable field qualification test requirements and procedures, which must be satisfied by the installed base of category 6 cabling in order to support the 10GBASE-T application.

10GBASE-T Application Support Lengths

Since the digital signal processing (DSP) capabilities of the 10GBASE-T application result in full internal pair-to-pair crosstalk cancellation, this application is particularly sensitive to undesired signal coupling between adjacent components and cabling.  This coupling is called alien crosstalk and the characterization of alien crosstalk in the installed category 6 cabling plant is the main focus of TSB-155-A.  Because the alien crosstalk in category 6 UTP cabling is extremely dependent upon installation practices (e.g. bundling, the use of tie-wraps, and pathway fill), performance values were developed based upon a “typical” worst case environment – meaning that 10GBASE-T should operate over category 6 UTP channel lengths of up to 37 meters and may operate over channel lengths of 37 to 55 meters of category 6UTP cabling depending upon the actual alien crosstalk levels present.  Since the overall foil in category 6 F/UTP cabling designs significantly reduces alien crosstalk, these length limitations are not applicable to F/UTP cabling.

Mitigation

TSB-155-A specifies recommended mitigation practices in the event that an installed category 6 channel does not satisfy the minimum alien crosstalk levels.  Mitigation techniques include using non-adjacent patch panel ports to support the 10GBASE-T application, separating or using improved equipment cords, using F/UTP equipment cords, unbundling cables, reconfiguring cross-connects as interconnects, and replacing category 6 components with category 6Acomponents.

Recommendations for New Installations

Category 6 cabling is not recommended for new installations targeted for support of the 10GBASE‑T application.  The reason for this is that, while field test devices for determining compliance to the new PSANEXT loss and PSAACRF (previously known as PSAELFEXT loss) parameters are just now being introduced to the market, the test methodology remains extremely time-consuming, overly onerous to implement, and may not be fully conclusive.  Furthermore, in a majority of installations, alien crosstalk mitigation will be required.  Often, the recognized mitigation methods cannot be easily implemented due to existing pathway fill restrictions and the potential need to replace components.  In addition, there is no guidance on qualification procedures for large installations or future MAC work.

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