“40Gb/s throughput claims from cabling manufacturers are not the same as 40GBASE-T application support claims”

What is the status of the 40GBASE-T Standard?  40GBASE-T is currently under development by the IEEE 802.3bq 40GBASE-T Task Force formed in March of 2013.  The target publication date, as noted on the group’s Project Authorization Request, is February of 2016.  The Task Force has active liaisons with TIA and ISO/IEC to ensure that cabling requirements under development will support the application.

What is the difference between a 40Gb/s throughput and a 40GBASE-T application support claim?  Since the processing capabilities of 40GBASE-T PHY (i.e. the chip technology that delivers the Ethernet bit stream) aren’t yet defined, it’s impossible to guarantee 40GBASE-T application support for any media – including Siemon’s TERA® category 7_A cabling.  Many cabling experts, including Siemon, have performed 40Gb/s throughput analysis using hypothetical PHY capabilities to explore technical feasibility and justify the initiation of a higher speed Ethernet project.   However, this research can be misinterpreted as a statement about the ability of a system to specifically support the 40GBASE-T application. For example, Nexans, in conjunction with the University of Pennsylvania, theoretically demonstrated 40Gb/s throughput over 100 meters back in 2009. More recently, TE has released a white paper also claiming theoretical support of 40Gb/s.  While valuable for research purposes, these papers are not the same as making a 40GBASE-T application support claim because the assumptions used to make a 40Gb/s throughput statements have been based on analysis using noise cancellation levels that are far better than a real-world commercially viable PHY chipset can achieve.  In other words, statements that refer to a system’s ability to support “40Gb/s throughput” have no relevance on future compatibility with 40GBASE-T network equipment, simply because these claims and models are de-coupled from technical requirements that are yet to be specified by IEEE 802.3bq.

Are any manufacturers making a 40GBASE-T application support claim?  If the ratified 40GBASE-T Standard specifies compatibility with category 7_A or class F_A cabling, Siemon will provide retroactive and future 40GBASE-T applications assurance for all Siemon TERA category 7_A cabling systems that meet the length and topology constraints specified by that Standard. For example, if the IEEE 802.3bq Standard specifies compatibility with category 7_A or class F_A cabling having up to two connections and lengths up to 30m, we will provide 40GBASE-T applications assurance for installed Siemon TERA category 7_A cabling channels that fall within those implementation requirements.  No manufacturer is making an unconditional 40GBASE-T application support claim at this time.

When will Siemon provide a 40GBASE-T application support claim? Siemon will provide a 40GBASE-T applications support claim for specific cabling system types, lengths and topologies when Standards requirements that clearly define the cabling characteristics, baud rate, and other digital signal processing capabilities of the 40GBASE-T PHY are finalized.

Will category 8 cabling support 40GBASE-T?  When published, TIA and ISO/IEC category 8 cabling will support 40GBASE-T.  However, category 8 cabling requirements are currently in a high state of flux and claims of meeting draft category 8 performance specifications are not meaningful at this early stage of development.  Siemon cautions that a demonstration of performance to a draft category 8 cabling specification is not the same as a 40GBASE-T application support claim.