Do I need to test for Alien Crosstalk for 10GBASE-T? | Fluke Networks

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Do I need to test for Alien Crosstalk for 10GBASE-T?

Alien Crosstalk is a key parameter that will affect the ability of 10GBASE-T to operate correctly. For 10GBASE-T, Alien Crosstalk represents above 90% of the total noise budget allocated for successfull operation. So to dismiss it seems illogical. As far as the standards are concerned, it is an optional test. In fact, all testing is optional. Over the years, the industry has realized the importance of certification of cabling systems. "To test is to know". This remains true for Alien Crosstalk testing. Do you need to test Alien Crosstalk?

The decision to test Alien Crosstalk will be made by the: 

            a) Customer 
            b) Installer 
            c) Consultant 
            d) Cabling vendor offering the warranty.

If everyone is in agreement not to test, then you do not have to test. The question whether to test for Alien Crosstalk compliance is most often posed when it concerns an installation of screened or shielded cabling. BUT, you should be aware that not all screened cabling and screened connecting hardware/patch panels are created equal. Furthermore, there is the quality of installation workmanship and the integrity and adequacy of the electrical grounding system in combination with the connection of the screens to ground. If we look to draft IEC 61935-3 for guidance, it suggests a sampling rate of 1% or 5 links whichever is greatest. It further goes on to say that; "When the margin of PS ANEXT and PS AACR-F has reached 5 dB for the long length links, further alien crosstalk testing of long length links can be discontinued when the number of measured disturbed links is at least 3.

Given the importance of Alien Crosstalk, it would be prudent to adopt the IEC 61935-3 guidelines and conduct a limited sample of Alien Crosstalk testing. This will provide further assurance to all parties that the system will support 10GBASE-T.

Author: Adrian Young

Creation Date: 2014-02-18

Last Modified: 2014-02-18