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Understanding 40Gb/s and 40GBASE-T Performance Claims

 Cabling Standards News  Comments Off
Jun 192013
 

“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 (http://www.ieee802.org/3/bq/index.html) 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 7A 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 7A or class FA cabling, Siemon will provide retroactive and future 40GBASE-T applications assurance for all Siemon TERA category 7A 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 7A or class FA cabling having up to two connections and lengths up to 30m, we will provide 40GBASE-T applications assurance for installed Siemon TERA category 7A 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.  For example, a recent “technical feasibility” demonstration by CommScope presented to IEEE 802.3bq showing a pre-market category 8 system meeting TIA draft 0.6 requirements does not meet the revised requirements of TIA draft 0.8.  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.

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Navigating the Pros & Cons of Structured Cabling vs. Top of Rack in the Data Center

 Cabling Standards News  Comments Off
Apr 302013
 

A whitepaper from the Communications Cable and Connectivity Association’s (CCCA) data center committee is a guide for data center professionals and IT managers. The whitepaper examines the many factors to consider when evaluating top of rack (ToR) and structured cabling configurations, including the impact of those configurations on total management; scalability and upgrades; interoperability; equipment, maintenance and cabling costs; port utilization; power consumption and cooling requirements.

The Communications Cable and Connectivity Association’s (CCCA) newly formed data center committee has developed a whitepaper that is a guide for data center professionals and IT managers.

The whitepaper, Navigating the Pros & Cons of Structured Cabling vs. Top of Rack in the Data Center, examines the many factors to consider when evaluating top of rack (ToR) and structured cabling configurations. Topics include the impact of those configurations on total management; scalability and upgrades; interoperability; equipment, maintenance and cabling costs; port utilization; power consumption and cooling requirements.

This whitepaper is the first of many planned contributions from the data center committee. “The pace at which data center hardware and space configuration changes is daunting. CCCA recognized both a need and an opportunity to help guide data center cabling decisions by providing the latest studies, options and expert views from the industry’s leading cable and connectivity manufacturers,” states Executive Director Frank Peri. “As with our other working groups, the goal of the CCCA data center committee is to add our voice to the development of industry codes, standards and other important resources.”

The Data Center committee plans an active and ongoing global communications program using a variety of venues. “The global data center environment is dynamic and challenging for those designing the cabling network,” adds Bob Carlson of the Siemon Company and Chair of the new committee. “Cabling systems design and topology choices have a significant impact on server and port utilization, operating efficiencies and even energy consumption. The new committee strives to provide information and insights that are relevant globally to assist design professionals and end users to make well-informed cabling decisions.”

CCCA is comprised of leading manufacturers, distributors and material suppliers who are committed to serve as a major resource for well-researched, fact-based information on the technologies and issues vital to the structured cabling industry. For information updates on data center and other timely industry topics, visit the association’s website at http://www.cccassoc.org, sign up for the quarterly newsletter, check the Communications Cable & Connectivity LinkedIn group, and CCCA’s YouTube page.

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The TIA Great Cat 8 Debate and ISO/IEC Cabling Update

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Mar 182013
 

After debating the issue for three meetings cycles, the TIA TR-42.7 Copper Cabling Subcommittee adopted “category 8” as the name of their next generation balanced twisted-pair cabling system that is currently under development to support 40Gb/s transmission in a 2-connector channel over some distance up to at least 30 meters.  The issue of what to call this new system was a subject close to the hearts of many subcommittee members and both proponents and opponents of the new name argued tenaciously for their positions. However, the real question is just how much confusion the name category 8 is going to cause for the industry.

Traditionally, cabling categories are supersets of each other – meaning that a higher category of cabling meets or exceeds all of the electrical and mechanical requirements of a lower category of cabling and is also backwards compatible with the lower performing category.  While TIA specifies cabling systems up to category 6A performance, TIA chose not to adopt category 7 or 7A as published by ISO/IEC.  TIA has now decided to call their next generation cabling system “category 8” to avoid confusion with published ISO/IEC category 7 and category 7A standards, which are indeed supersets of each other and of category 6A.  While it’s true that the currently proposed category 8 specifications tentatively describe transmission performance up to 2 GHz whereas ISO/IEC specifies category 7A requirements up to 1 GHz, the performance limits proposed for category 8 today do not meet or exceed category 7A requirements up to 1 GHz.

So, herein lays the conundrum: category 8 is expected to have a different deployed channel topology and will not be a performance superset of category 7A.  In fact, for every transmission parameter except return loss, ISO/IEC category 7A channel and permanent link limits are more severe than those proposed by TR-42.7 for category 8 up to 1 GHz.  In the case of internal crosstalk parameters, the differences are significant: with category 7A beating out category 8 performance by more than 20 dB!

So what about bandwidth of specification?  While category 7A is currently specified to 1 GHz, new work items, such as the nearly finalized IEC 61076-3-104, 3rd edition standard for category 7A connectors, are extending category 7A performance characterization out to 2 GHz.  The situation of having two cabling specifications specified to 2GHz, with category 8 having much lower performance than category 7A, is really going to create confusion.

What to name next generation cabling systems is not just a TIA issue; ISO/IEC also faced the same challenge with their new project to define two new grades of cabling (shielded and fully-shielded) to support 40 Gbit/s data transmission.  ISO/IEC recently adopted class I to describe cabling constructed from shielded modular RJ-45 style category 8.1 components and class II to describe cabling constructed from fully-shielded category 8.2 components.

Until the processing capabilities of a 40 Gb/s Ethernet (40GBASE-T) application are finalized, it’s too early to guarantee 40GBASE-T application support distance for any media. However, fully-shielded category 7A solutions, such as Siemon’s TERA™, remain the highest performing twisted-pair cabling system commercially available today.  Not only do these solutions provide higher EMI/RFI immunity and more flexible cable sharing capabilities than RJ-45 style solutions, but ISO/IEC is actively working on a project to characterize the capability of existing category 7A cabling to support 40 Gbit/s data transmission.

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What about Category 7A Cabling?

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Feb 222013
 

The cover story of the latest edition of Processor magazine features an exciting story on Category 7A entitled “What About Category 7A Copper Cabling?”  In the article, you’ll learn how Siemon TERA remains today’s highest performing twisted-pair cabling system despite TIA’s new Category 8 nomenclature.

View the digital edition of Processor Magazine.

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IEEE 802.3 Study Group formed to investigate Next Generation BASE-T

 Cabling Standards News  Comments Off
Aug 142012
 

The wait is over!  During this week’s IEEE 802.3 meetings in San Diego, a new Study Group was formed to investigate creating a “Next Generation BASE-T” balanced twisted-pair copper Ethernet application.  A call-for-interest (CFI) presentation profiled the ever increasing server uplink speeds found in the data center; leading to the prediction that 40 Gbps and even higher Ethernet speeds will be required to support these connections in the near future.  Discussion focused on the unique features and benefits of balanced twisted-pair cabling, including backward compatibility, auto-negotiation, and small form factor, that are driving the need for a Next Generation BASE-T data center application.  Once the Study Group is formed, issues such as reach, topology, media performance, throughput, and PHY (Ethernet chip) complexity will be investigated in detail.  61 individuals from 40 companies, including Siemon, formally supported the CFI presentation.

Here is the link to the IEEE 802.3 call-for-interest (CFI) announcement and slide presentation if you would like to learn more:http://www.ieee802.org/3/cfi/request_0712_1.html

IEEE press release for Next Generation BASE-T Ethernet:
http://standards.ieee.org/news/2012/802.3.html

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TIA Publishes New Standard for Telecommunication Administration

 Cabling Standards News  Comments Off
Aug 142012
 

The ANSI/TIA-606-B “Administration Standard for Telecommunications Infrastructure” published June, 2012.  This Standard specifies four classes of administration within buildings and between buildings based upon the complexity of the infrastructure being administered.  Administration requirements for commercial, industrial, residential, and data center premises are addressed.

Examples of recognized administration strategies include:

  • assigning identifiers to components of the infrastructure
  • specifying elements of information that make up records for each identifier
  • specifying relationships between these records to access the information they contain
  • specifying reports presenting information on groups of records, and
  • specifying graphical and symbolic requirements

The four classes of administration are:

  • Class 1 provides for the telecommunications infrastructure administration needs of a premises that is served by a single equipment room (ER)
  • Class 2 provides for the telecommunications infrastructure administration needs of a single building or of a tenant that is served by single or multiple telecommunications spaces (e.g., an equipment room with one or more telecommunications rooms) within a single building
  • Class 3 provides for the telecommunications infrastructure administration needs of a campus, including its buildings and outside plant elements
  • Class 4 provides for the telecommunications infrastructure administration needs of a multi-campus/multi-site system

Refer to the Siemon Standards Informant (http://blog.siemon.com/standards/) to learn more.  Copies of the Standard may be purchased from the IHS Standards Store (http://global.ihs.com).

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TIA-942-A Telecommunications Infrastructure Standard for Data Centers

 TIA, TIA-942-A Telecommunications Infrastructure Standard for Data Centers  Comments Off
Jul 172012
 
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Siemon’s Stance on White Paper Titled, “Suitability of Category 7A/Class FA As A Future Proofing Media For 40 Gbps Applications”

 Cabling Standards News  No Responses »
May 312012
 

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 7Acompliance 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.

In summary:

  • 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.

 

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ISO/IEC

 ISO/IEC  Comments Off
Mar 202012
 

 

ISO/IEC Cabling System Standards

ISO/IEC Technical Reports

ISO/IEC Activity

Resources
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IEEE Std 802.3bf-2011: Ethernet Support for the IEEE P802.1AS Time Synchronization Protocol

 IEEE 802.3: Ethernet, IEEE Std 802.3bf™-2011  Comments Off
Dec 152011
 

Ethernet Support for the IEEE P802.1AS Time Synchronization Protocol is specified in:

IEEE Std 802.3bf-2011 – IEEE Standard for Information technology– Local and metropolitan area networks– Part 3: CSMA/CD Access Method and Physical Layer Specifications Amendment 7: Media Access Control (MAC) Service Interface and Management Parameters to Support Time Synchronization Protocols

 

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