Crossover between two LAN cards

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 Question by Mehrdad Biglari posted 04 Mar 2004
 
I have two 10/100 Mb/s LAN cards(D-Link) and I have a 20 meter Cat 5 UTP (Crossover) between them but it cant function in 100Mb/s and it just works in 10Mb/s.
Why and what should I do?
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 Answer by Joseph Golan posted 08 Mar 2004
Dear Mehrdad,

Are you sure that the cross over cable is constructed properly. I symptons you are reporting are typical when the cable is improperly made up causing a split pair. A split pair will seriously degrade the throughput.

The pairs are best identified as pins 1&2 and 3&6 and should be color coded as white/orange and white/green. At the two ends of the cable, the pairs are reversed (1&2 goes to 3&6 and 3&6 go to 1&2. if the complete twisted pair is not used and other conductors are picked up then you have a split pair. The last thing on this is to make sure that your 20 meter cable is not kinked or crushed in any way as this too will affect the performace of the cable.

Sincerely,
Joseph Golan, RCDD

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