Q: When will category 8 standards be ratified? ANSI/TIA‑568‑C.2‑1, which contains requirements for category 8 cabling constructed from category 8 components to support the 25GBASE‑T and 40GBASE-T applications, was approved for publication in June, 2016. ISO/IEC 11801-1 is currently under development and will contain requirements for class I cabling constructed from category 8.1 components and class II cabling constructed from category 8.2 components. Draft ISO/IEC class I and II cabling specifications are mature and currently circulating for final industry comment and review, with ratification expected in early 2017. Note that TIA is currently investigating the specification of class II cabling requirements to harmonize with ISO/IEC.
Q: What are the main characteristics of category 8 cabling and how will they affect data center infrastructure? Class I, class II, and category 8 cabling is characterized to 2 GHz and intended to support 30 meter cabling channels that contain no more than 2 connectors. These channels and the emerging 25G/40GBASE-T applications that they support are specifically targeted for deployment at the data center “edge” where server to switch connections are made. Data center designers that can arrange their rack and cabinet layouts to support maximum 30‑meter channel connections at these locations today will be well-positioned to migrate to 25G/40GBASE-T when the technology becomes available.
Q: How is the performance of category 8 cabling improved over its predecessor versions? Interestingly, for every transmission parameter except return loss, ISO/IEC class FA channel and permanent link limits are more severe than those proposed specified for class I and category 8 up to 1 GHz. In the case of internal crosstalk parameters, the differences are significant; with class FA beating class I and category 8 performance by more than 20 dB! Class I and category 8 do have an advantage in that they are characterized out to double the bandwidth of class FA. Class II requirements represent the most stringent performance specifications for balanced twisted-pair cabling that the industry has ever seen. The end result is that class I, class II, and category 8 cabling will offer unprecedented signal-to-noise margin for support of 25 Gb/s and higher transmission rates.
Q: Is category 8 cabling mainly for support of 40GBASE-T? Class I, class II, and category 8 cabling has a unique channel topology that is optimized for support of both 25GBASE‑T and 40GBASE‑T server to switch connections in the data center.
Q: Will category 8 cabling be backward compatible with lower category cabling? Class I, class II, and category 8 cabling will be backward compatible with lower classes and categories of cabling. For example, a category 8 connector can be used in a class EA channel and class EA channel performance will be assured.
Q: Will a new type of connector be required for category 8 or can a modular eight-position modular RJ-45 interface be used? Class I and category 8 cabling specifications support modular RJ-45 style connectors. The performance associated with class II cabling can only be realized when category 8.2 cables are used in conjunction with non RJ-45 interfaces such as the Siemon TERA® connector.
Q: Will category 8 cables be physically similar to category 6A and 7A cables and can category 8 cabling be installed leveraging existing infrastructure and termination methods? Class I, class II, and category 8 cabling will have a similar “look” and “feel” to lower grades of cabling and installation methods will not be significantly different. This cabling may be installed in existing pathways and conduit; however, the existing infrastructure will need to be upgraded to support 25GBASE-T and 40GBASE-T.
Q: Will category 8 cabling require more power? Class I, class II, and category 8 cabling does not require more power to operate. In fact, due to lower dc resistance and insertion loss, these cables may more efficiently support remote powering applications (e.g. Power over Ethernet or “PoE”) and offer improved heat dissipation. Higher speed Ethernet equipment, however, does tend to consume more power and it is realistic to expect that first generation 25G/40GBASE-T equipment will consume more power per port than 10GBASE-T equipment. As technology evolves, it is likely that 25G/40GBASE-T equipment port power consumption will be comparable to 10GBASE-T equipment port power consumption.
Q: Will the arrival of category 8 cabling impact the adoption of category 7A cabling? Since class II channel performance can be achieved with many of the category 7A connectors (e.g. Siemon TERA) that are commercially available today, end-users should not see the arrival of class I and category 8 products significantly change the landscape of available high speed cabling options. In fact, the superior performance offered by class II cabling may encourage more users to adopt fully-shielded cabling solutions constructed from non RJ-style connectors. Furthermore, while it’s too early to guarantee 25GBASE-T application support, there are efforts in place to characterize the capability of existing installed class FA/category 7A cabling plants to support 25 Gb/s data transmission.