By Valerie Maguire and John Siemon, Siemon -- The purpose of this document is to communicate Siemon’s position in response to a recent paper from a competitor titled, “Suitability of Category 7A/Class FA As A 'Future Proofing' Media For 40 Gbps Applications,” dated April 2012. This document also conveys Siemon’s interpretation of standards activities relating to suitability of class FA cabling (comprised of category 7A components) for future networking applications having transmission rates above 10Gbps.
The TIA TR-42.7 Baseline Objectives for Next Generation Cabling identify the characteristic, "must exceed the TIA category 6A specification in at least 1 parameter" as "nice to have". Furthermore, the IEC/PAS 61076-3-104 Standard, which describes the performance of the Siemon TERA interface, is being updated to support frequencies up to 2 GHz. Because class FA exceeds all category 6A specifications for every transmission parameter, class FA cabling is better positioned to support extended lengths, reduced latency, and reduced power consumption than any other copper media type, when a 40Gbps application is finally approved. In the absence of application objectives or an IEEE 802.3 40Gbps call-for-interest (CFI), no one, including Siemon, can make definitive claims about the ability of specific twisted-pair cabling implementations to reliably support transmission rates up to or beyond 40Gbps at this time. Our position on the inaccurate statements included in the competitor paper regarding class FA cabling is provided below:
1. Misstatement: “[The TIA Category 7A PAR] was not accepted by TIA TR-42.7 as sufficient to meet the needs of 40GBASE-T”
Fact: The TR-42.7 motion for this new project request failed to achieve greater than 2/3rd’s majority support by one vote (10 votes in favor and 5 votes opposed). While there was great interest in adopting class FA/category 7A requirements, there were several voting members who expressed the opinion that 40Gbps speeds could be realized by cabling with performance less stringent than class FA.
2. Misstatement: “Whether the crosstalk is mitigated via signal processing or cable sharing, from this perspective, Category 7A and Category 6A cabling in the absence of alien crosstalk are equivalent.”
Fact: An Ethernet physical layer device (PHY) can detect less noise in a screened/shielded system during the training mode and back-off on the FEC (forward error correction) algorithm, which results in lower power consumption. Power savings is highly variable, but can be up to 10% with incremental savings based on channel length and noise immunity. For example, power back off savings potential is greater for category 6A F/UTP channels versus category 6A UTP channels, and is greater for category 7A S/FTP channels versus category 6A F/UTP channels.
3. Misstatement: “Adapter cords are not an acceptable solution since the customer will be forced to maintain two sets of equipment cords to ensure interoperability and portability between new and legacy installations.”
Fact: Hybrid cords that adapt from one interface to another are commonly used in both twisted pair (e.g. block-based systems) and optical fiber (e.g. MPO/MTP to LC systems). These solutions are fully standards compliant and, in some cases, provide additional security. In no case is there a need for customers to maintain two sets of equipment cords.
4. Misstatement: “The majority of category 7A installations are installed as a hybrid system using category 7A cable with category 6A shielded RJ45 connectors and cords. This essentially makes the installed cabling system a category 6A solution.”
Fact: Only category 7A connectors are deployed in Siemon class FA cabling systems. The RJ 45 modular plugs at both ends of the channel are considered equipment connections and are outside of the scope of both the TIA and ISO/IEC channel definitions as shown in the figure excerpted from ANSI/TIA-568-C.2 below. Irrespective of the equipment interface, class FA compliant cabling channels comprised of category 7A compliance cables and connectors provide significantly higher channel capacity than any other class or category of balanced cabling.
5. Misstatement: “At present, category 7A is a cabling specification that is not called out by any LAN or SAN application Standard”.
Fact: Class F cabling (comprised of category 7 components) is explicitly called out as a recognized media in the IEEE 802.3an 10GBASE-T Standard and the newer class FA specification is expected to be incorporated into the next edition IEEE 802.3-2012 Standard. Furthermore, ISO/IEC has initiated a new Work Item Proposal tentatively titled, “ISO/IEC 11801 99-x Guidance for balanced cabling in support of at least 40 GBit/s data transmission, Part 2” to develop guidelines addressing the 40 Gb/s capacity exhibited by existing classes of cabling, including class FA.
While there is no formal IEEE 802.3 40Gbps project Call-For-Interest at this time, all early indicators show that there is great industry commitment to and investment in the future of copper-based Ethernet. Siemon actively participates in the TIA and ISO/IEC Cabling Standards committees that are developing modeling and performance specifications, in addition to the IEEE 802.3 Ethernet Working Group. We stand behind our mission to engineer the highest performing cabling solutions and provide fact-based product selection information to our customers.
• Siemon’s class FA compliant TERA solution is the highest performing copper system on the market (globally) and, as such, is better positioned to support future and emerging applications than any other copper balanced twisted-pair media type.
• Screened and fully-shielded systems offer power-saving advantages to PHY developers.
• Hybrid cords are approved and commonly used in both copper and optical fiber cabling systems. The RJ-45 plugs at the channel ends are used for equipment connections and are not part of the TIA and ISO/IEC channel models.
• Siemon participates heavily in standards development and is conservative in our statements and performance claims.
Both Valerie Maguire, global sales engineer for Siemon, and John Siemon, the company's VP of global operations and CTO, were contributors to this article.