CNX ANIXTER

Fluke Networks DTX-1800 cable analyzer supports 10GBASE-T specifications and similar cabling standards (TIA TSB-155; currently in draft 5). Therefore, it can be used to ensure that each installed cabling link meets the transmission requirements outlined in the standards from 1 to 500 Mhz, and that between-cable coupling, also called Alien Crosstalk, meets the necessary specifications. The DTX-10G kit provides all the accessories needed to perform in-field Alien Crosstalk measurements using the DTX-1800.

In-channel Mitigation

If some of the installed links do not pass the in-channel tests, it will be necessary to inspect and upgrade all the channels to meet this first requirement for 10GBASE-T transmissions. In order to achieve this, it is advisable to use the diagnostic features of the DTX Series testers to guide you through the zone where there is a problem and suggest a corrective application.

In case an auto-test fails, you can press the fault Info key on the tester to obtain further data. These data may be inconclusive if the failures occur in the higher frequency ranges of the test spectrum. Therefore, we would like to provide some guidelines for troubleshooting. It is likely that most failures not identified in the diagnosis are related to inadequate performance of the link connections at higher frequencies ranges.

These are some recommended corrective actions that must be executed in the suggested sequence:

1. Replace the work area, patch, and/or equipment cords with Cat 6A cords.

2. Reconfigure the cross-connect as an interconnect.

3. Replace the interconnect with a Cat 6A interconnect

4. Replace the consolidation point connector with a Cat 6A consolidation point connector.

5. Replace the work area outlet connector with a Cat 6A work area outlet connector.

To see the effect of each upgrade step, it is recommendable that a new test is performed on the link. If it passes the test, the corrective action has been successful.

Alien Crosstalk Mitigation

The Alien Crosstalk measurement tests are typically performed on a selected group of links. It is essential that the longest links are tested first. In the standards, the tested link is usually referred to as “disturbed link". To make the distinction between disturbed and disturber link easier, it is better to refer to the perturbed link as the “victim link".

All the links in the same bundle as the victim link should be included as disturber links for Alien Crosstalk tests. In addition, it is advisable to make sure that you haven included in the list of disturber links those links that are terminated in adjacent positions in the Telecommunication Room patch panel.

Interpreting test results

The Alien Crosstalk tests are executed under control of the AxTALK Analyzer software, which executes on a Microsoft Windows-based personal computer or laptop.

The computer connects to the DTX-1800 main unit using a USB connection. The AxTalk Analyzer software controls the DTX-1800, uploads all of the measurement results, and processes this data in real time to produce the power sum test results for the wire pairs in the victim link.

As the crosstalk effects of wire pairs in additional disturber links are measured, the AxTALK Analyzer automatically adds and displays their effect by calculating the power sum AXTalk test result for all the disturbers included in the test so far on each victim wire pair.

The individual pair-to-pair Alien Crosstalk measurements from which the power sum parameters are calculated are stored in the PC’s memory. You can at any time investigate the effect of one disturber onto the four wires pairs of the victim link.

In order to visualize the worst case PS ANEXT margin for each wire pair in the victim link, just click on the “Result Data” button, (towards the left of the screen, just left of the button labeled “Run test”) and a display will pop up.

It should also be observed that the margin of the test results for one disturber is significantly better than the margin for the combined effect of five disturber links.

Identify the disturber contributing the worst amount of ANEXT

In case the PSANEXT test fails, it would be necessary to know which disturber links are contributing the most amount of ANEXT in order to arrive at a strategy to correct the problems.

We can investigate the contribution made by individual disturber links. Disturber links yielding the smallest worst case margin numbers (or nega¬tive numbers) are the worst offenders (biggest contributors to PS ANEXT). You can rank-order the links from worst to least amount of ANEXT coupling.

For each of the worst contributors, we can consider the corrective actions (alien crosstalk mitigation) listed below in order of priority:

1. Reduce the alien crosstalk coupling by separating the equipment cords and the patch cords and un-bundling the horizontal cabling.

2. An alternative to separating equipment cords is to utilize equipment cords sufficiently specified to
mitigate the alien crosstalk coupling such as Category 6 ScTP and Augmented Category 6.

3. Reconfigure the cross-connect as an interconnect

4. Replace connectors with Augmented Category 6

5. Replace the horizontal cable with augmented Category 6

After applying one of the mitigations, you should re-test the interaction between the victim link and the modified disturber to see whether a noticeable improvement has been achieved.

For further information on the test for 10 Gigabit cabling, visit the 10 Gig Solution Center at www.flukenetworks.com/10gig to get up to date on the latest standards upgrades.