How new testing standards affect you Singapore, Nov 2009 Adrian Young Sr. Customer Support Engineer
In this presentation, we will cover How ANSI/TIA-568-C.2 has consolidated all the different test plugs defined in the past to one single test plug and how that affects your test results Alien Crosstalk testing strategy and basic troubleshooting 1 jumper vs 3 jumper reference found in IEC 14763-3 Optical Time Domain Reflectometry testing as found in ANSI/TIA-568-C.0 and IEC 14763-3
Permanent Link test lead Ever swapped your test leads around and got a different result? It can t be the tester, it s the same tester you are using May be it s the test lead.. well kind off.. It s that RJ45 plug on the end of the lead that is causing it to change. ANSI/TIA-568-C.2 states:? The plug is terminated by hand, the variation of performance can be wide spread.
Test leads/plugs cause the biggest uncertainty If the performance of your plug changes, so does your NEXT margin It s the placing of the twisted pairs that affects it s performance It is a real struggle to create a test plug One solution remove the twisted pairs in the RJ45 plug
Test leads & plugs are critical for Category 5e, 6 and 6A Up until recently, there were three different test plugs specified for testing Category 5e, 6 and 6A ANSI/TIA/EIA-568-B.2 defined a test plug for Cat 5e ANSI/TIA/EIA-568-B.2-1 defined a test plug for Cat 6 ANSI/TIA-568-B.2-10 defined a test plug for Cat 6A With ANSI/TIA-568-C.2 there is now only one test plug for Cat 5e, 6 and 6A which is the same test plug found in ANSI/TIA-568-B.2-10 This is fantastic news for the entire industry. Connector vendors only have to worry about one test plug to tune their connectors to Cat 5e, 6 and 6A. For installers now, they can optimize their test results by using a test lead with an RJ45 plug that meets the requirements of ANSI/TIA-568-C.2
Test plug requirements ANSI/TIA-568-C.2 defines the test plug for NEXT FEXT Return Loss Laboratory technicians can spend weeks trying to make a test plug that meets the requirements it s generally understood that this is not practical In Annex C of ANSI/TIA-568-C.2 it talks about using a PCB (Printed Circuit Board) style RJ45 plug It is easier to produce a compliant test plug using a PCB substrate according to Annex E.2 of ANSI/TIA-568-C.2 1) Its properties have been designed to comply with electrical properties of the test plug described in clause C.4.10. 2) The construction is repeatable and consistent. 3) It is mounted to the test fixture without the use of twisted wire test leads, yielding a more consistent measurement result.
How a connector is tested in the laboratory ANSI/TIA-568-C.2 defines the test plug for NEXT, FEXT and Return Loss C.4.10.8.2 Test plug construction for return loss testing NOTES, Plugs of this type may be obtained from: Fluke Networks, Everett, WA or SMP Data Communcations, Swannanoa, NC. Alternative equivalent components may also be used. The closer your test plug is to the standard, the better your result
Alien Crosstalk (AxTalk) testing Values are found in ANSI/TIA-568-C.2 for the Perm. Link and Channel Methodology is found in the new ANSI/TIA-1152 Myth: You do not have to do Alien Crosstalk testing if it is a shielded cabling system Fact: Neither standard makes a distinction between UTP/FTP/STP when it comes to Alien Crosstalk testing Experience: Our experience shows that shielded cabling systems can fail Alien Crosstalk requirements if not installed correctly AxTalk is a sample test of the installation ANSI/TIA does not specify the sampling plan IEC 61935-1 no longer specifies 1% or 5 links whichever is the greatest Sampling instructions can be found in the new IEC 14763-2
How is it measured? A Disturber cable is picked (which one?) ANSI/TIA-568-C.2 and TIA-1152 give little guidance; short and long link IEC 61935-1 provides better information: 5.4.8.2 Selection of disturbing links Disturbing links shall include both of the following:» all of the links that are in the same cable bundle or the most consistently positioned relative to the disturbed link as disturbing links;» those that occupy adjacent positions to the left, right, above and below connections on the disturbed link on patch panels or multiple outlets. Let s take a look at a real world example:
Picking the Disturbed (Victim) link We know that the connectors contribute most of the PS ANEXT for Category 6A and Class E A cabling systems Do not pick the links/connectors at the end of a patch panel, since there are no adjacent connectors Do not pick the links/connectors at the end or a row/group for the same reason
Picking the Disturbed (Victim) link In the results software, we identified this link as one of our shortest links It is not at the end of the patch panel or group of connectors There are connectors/links above and below This truly is worst case
Picking the Disturber links Identify the bundle this Disturbed (Victim) link can be found in, shown in blue below This installation used bundles of 12 cables. We know that Alien Crosstalk between bundles is not significant, so we can focus on just the cables in the bundle
Picking the Disturber links We already know that the connectors contribute most of the PS ANEXT for Category 6A and Class E A cabling systems So you need to pick the connectors above and below 5.4.8.2 Selection of disturbing links Disturbing links shall include both of the following:» all of the links that are in the same cable bundle or the most consistently positioned relative to the disturbed link as disturbing links;» those that occupy adjacent positions to the left, right, above and below connections on the disturbed link on patch panels or multiple outlets.
The Alien Crosstalk Measurement (PS ANEXT)
Troubleshooting Alien Crosstalk Failures Disturber Ranking Here we see the Alien Crosstalk is coming from the adjacent links, we therefore know this is a connector issue and not a cable issue
ANSI/TIA-568-C.0 Fiber Testing (Tier 1) 6.4.3.1 General Link attenuation is measured using the reference methods specified by TIA- 526-14-A for multimode and TIA-526-7 for single-mode. The one cord reference method is preferred for both multimode and single-mode. Other methods as detailed in the above standards may be applied. Test documentation should include the test method applied. Let s take an example to understand how this is done:
ANSI/TIA-568-C.0 Fiber Testing (1 jumper reference) The test reference cord is removed from the Input, this is ok You must NEVER remove the cord from the output (source)
ANSI/TIA-568-C.0 Fiber Testing (1 jumper reference) A known good test reference cord is connected to the Input port
ANSI/TIA-568-C.0 Fiber Testing (1 jumper reference) And then connect to the link to be tested 100 m Loss Budget = 1.85 db 0.75 db + 0.35 db + 0.75 db
IEC 14763-3 Three Jumper Reference The reference is set (cords zeroed out)
IEC 14763-3 Three Jumper Reference The middle test reference cord is removed
IEC 14763-3 Three Jumper Reference And then connect to the link to be tested Loss Budget for multimode is calculated as follows: Loss of fiber under test + Loss of Splices + Loss of Connectors - 0.1 db - 0.1 db + 0.3 db + 0.3 db 100 m Loss Budget = 0.75 db 0.35 db + 0.0 db + 0.0 db - 0.2 db + 0.6 db
ANSI/TIA-568-C.0 Fiber Testing (Tier 2) OTDR (Optical Time Domain Reflectometer) is now part of 568-C.0 OTDR testing was specified in TIA TSB-140 Feb 2004 (not a standard)
Thank you for your time Questions? adrian.young@flukenetworks.com