 |
Testing 10 Gigabit/sec Ethernet Over Copper and Fiber Cabling
Installing and maintaining a reliable physical cable plant is essential to the well being of today's mission-critical LANs. New challenges arise as these networks migrate to higher speeds like 10 Gig, especially for Unshielded Twisted Pair (UTP) networks. The IEEE (Institute of Electrical and Electronics Engineers) standards board approved the standard for 10 Gigabit/sec Ethernet over twisted-pair cabling (10GBASE-T) in June 2006. We will explain the applicable cabling standards.
Cabling Industry Standards
The cabling industry is in the process of developing and publishing two different kinds of standards that can be applied when you plan to deploy 10 Gigabit/sec Ethernet (10 GbE). The first set of documents addresses the specific cabling performance requirements for 10GBASE-T. The TIA version of this effort will result in the publication of Technical Systems Bulletin 155 (TIA TSB155). The International Organization for Standardization (ISO) is working on a similar document to be called TR 24750. The second set of documents will define a new cabling type that will be called Augmented Category 6 (Cat 6A) and Augmented Class E (Class EA).
TIA TSB155 or ISO TR24750
A TSB typically formulates guidelines and is not a standard as such. The guidelines in TSB155 address what one can and should do to use or adopt Category 6 (Cat 6) cabling for the transport of 10GBASE-T signaling. The installed Cat 6 links should be tested in the field to certify that they pass the specified test parameters over the bandwidth required to support 10GBASE-T (1 through 500 MHz). Due to the much higher frequencies required to support 10GBASE-T transmission, a new set of transmission noise sources that could safely be ignored, now take center stage. These noise sources pertain to Alien Crosstalk (AXTALK), the crosstalk between wire pairs in adjacent cables. General expectations are that AXTALK for Cat 6 UTP cables less that 55 meters in length will meet the requirements for 10GBASE-T. AXTALK can, however, also be induced in patch panels and in connecting hardware. For all installed Cat 6 (Class E) cabling links field certification must include tests to assure that AXTALK test parameters pass the requirements. The TIA TSB155, currently in draft 5, is expected to be approved and published in the Fall of 2006. The ISO Technical Report is also expected to publish in late 2006 or early 2007. It is important to note that the channel specifications in these guideline documents are identical to the cabling specifications in the IEEE 10GBASE-T standard. The IEEE document only specifies channel performance while the cabling industry publishes performance specifications and limits for the permanent link as well as for the channel.
Standards for “Augmented” Cabling Systems
The new “Augmented” cabling types define a higher level of performance for the cabling performance as well as for the Alien Crosstalk characteristics of a cabling system. The Augmented cabling types are being designed to support 10GBASE-T over a full 100 m horizontal channel. The TIA Cat 6A standard will be published as Appendix 10 to the TIA/EIA-568-B.2 standard. The ISO Class EA cabling standard will be published in a new edition of the 11801 standard. New cabling standards require specifications for each component such as cable, each type of connecting hardware components, patch cords, etc. in addition to channel and permanent link specifications. Although general agreement has been reached on the channel specifications, a significant amount of work remains and the Augmented cabling standards will very likely not be completed until mid 2007.
The field certification of twisted-pair cabling for deployment of 10GBASE-T includes two test phases. The first phase certifies the transmission capability and quality of each individual link. This phase evaluates all cabling test parameters that are currently specified in the TIA/EIA-568-B document for Cat 6 or in ISO 11801 for Class E. The test limits are identical to the limits for Cat 6 (Class E) up to 250 MHz but the frequency range of these tests is extended to 500 MHz.
The second test phase encompasses certification of the cabling system for compliance with the Alien Crosstalk performance requirements. Alien Crosstalk certification for 10GBASE-T should include sample testing of some links in a bundle to verify compliance with AXTALK test parameters.
In summary, 10GBASE-T requires higher bandwidth, higher dynamic range in field measurements and new installation guidelines to combat alien crosstalk. Existing Level III field testers will not be able to support 10GBASE-T. For an in-depth overview on the developments of the 10GBASE-T Standard, a technical look at Alien Crosstalk, measurement methods and certification strategy, best practices for design and installation and, check out the White Paper above titled “Cabling Requirements for 10 Gigabit/sec Ethernet over Twisted-pair Cabling (10GBASE-T)”. Be sure to bookmark this page and check back often to see 10 Gig standards updates.
|
|
|
|