Twisted Pair Cabling and 10 Gigabit Cabling
Certifying a twisted pair copper cabling system for the deployment of 10 Gigabit per second Ethernet.
Widespread use of 10GBASE-T over twisted-pair copper cabling is taking off in the data center. Active devices like switches, servers, and NIC cards are becoming available to support 10GBASE-T. The Institute of Electrical and Electronics Engineers (IEEE) standards committee approved the 10GBASE T standard, IEEE 802.3an, back in June 2006. That standard defined the minimum level of performance for twisted pair copper cabling. In addition, the cabling industry developed Category 6A and Class EA links to support 10GBASE-T over a 100 m (328 ft.) twisted pair link.
Certification and Standards
Certification of the cabling system provides the assurance that that the installed cabling system delivers the bandwidth and performance needed for the reliable operation of 10GBASE-T before the network devices are purchased and installed.
Existing Category 6 or Class E cabling systems may satisfy the 10GBASE-T requirements established in IEEE 802.3an. However, these legacy cabling systems are limited in the length (35 m), over which they meet the transmission requirements. Re-certification of these installed links against the IEEE 802.3an (also TIA-TSB155 or ISO TR 24750) will deliver the definitive answer.
Field certification of installed twisted-pair cabling for 10GBASE-T includes all the test parameters that are specified in the ANSI/TIA-568-C.2 and ISO/IEC 11801:2011 Edition 2.2 standards for Category 6A/Class EA links. Table 1 lists these test parameters. The major change for 10GBASE-T is the frequency range for these tests, now extending to 500 MHz in order to support the higher data rates of the 10GBASE-T signaling technology. These cabling standards refer to the legacy test parameters listed in table 1 as the “In-Channel” test parameters. We must add alien crosstalk test parameters to complete the field-certification effort for 10GBASE-T.
|Test Parameter – ‘Old’ Name||Test Parameter – ‘New’ Name|
|Insertion Loss (IL)||Insertion Loss (IL)|
|Near End Crosstalk (NEXT)||Near End Crosstalk (NEXT)|
|Power Sum Near End Crosstalk (PS NEXT)||Power Sum Near End Crosstalk (PS NEXT)|
|Attenuation to Crosstalk Ratio (ACR)||Attenuation to Crosstalk Ratio – Near End (ACR-N)|
|Power Sum Attenuation to Crosstalk Ratio (PS ACR)||Power Sum Attenuation to Crosstalk Ratio – Near End (PS ACR-N)|
|Far End Crosstalk (FEXT)||Far End Crosstalk (FEXT)|
|Equal Level Far End Crosstalk (ELFEXT)||Attenuation to Crosstalk Ratio – Far end (ACR-F)|
|Power Sum Equal Level Far End Crosstalk (PS ELFEXT)||Power Sum Attenuation to Crosstalk Ratio – Far End (PS ACR-F)|
|Return Loss (RL)||Return Loss (RL)|
|Wire Map||Wire Map|
|Propagation Delay||Propagation Delay|
|Delay Skew||Delay Skew|
Alien crosstalk takes place between wire pairs in different, adjacent cabling links. Therefore, the Alien Crosstalk test parameters are referred to as “Between-Channel” test parameters. Alien crosstalk may occur between any two-wire pairs in a cabling bundle. The combined impact of all wire pairs in the bundle upon the wire-pair-under-test have to be measured. The test parameters to capture this combined impact are power sum alien near end crosstalk (PS ANEXT) and power sum alien attenuation-to-crosstalk-ratio from the far end (PS AACR-F). Alien crosstalk is the most significant disturbance or noise source for the 10GBASE-T application over twisted pair cabling. The alien crosstalk performance will determine the distance limit for installed Category 6 or Class E cabling.
The Fluke Networks’ DSX-5000 CableAnalyzer™ tester fully supports the field certification process of twisted pair cabling against the IEEE std. 802.3an and cable industry standards. The DSX-5000 not only performs the “In-Channel” link performance but also the “Between-Channel” alien crosstalk performance. Details about the test methodology and the test parameters are described in the white paper “How to Certify Twisted-Pair Cabling for 10 Gbps Ethernet”.
Proper certification of any cabling system whether new or old, delivers the definitive answer whether the system as installed will support 10GBASE-T. Choose the IEEE standard (criteria) to certify installed Category 6 or Class E cabling. Category 6A/Class EA cabling systems should of course meet the requirements established in ANSI/TIA and ISO/IEC standards. These requirements exceed the 10GBASE-T performance requirements.