Gigabit over copper crossover cable FREE cabling and networking Helpdesk
 Question by Ryan Lundebrek posted 21 Sep 2000
 Gigabit over copper crossover cable
I am trying to find out the pin assignments to make a Gigabit over copper crossover cable. Where can I find this information?
 Answer by Roman Kitaev posted 25 Sep 2000
Hi, Ryan!

Thanks for interesting question. Following it, I looked for an answer into the 802.3ab 1000Base-T standard and found the following:

The 1000Base-T network card uses the following pinout in its port:

Contact Signal
1 BI_DA+
2 BI_DA-
3 BI_DB+
4 BI_DC+
5 BI_DC-
6 BI_DB-
7 BI_DD+
8 BI_DD-

The 1000Base-T switches and repeater use the following pinout in its ports with internal crossover:

Contact Signal
1 BI_DB+
2 BI_DB-
3 BI_DA+
4 BI_DD+
5 BI_DD-
6 BI_DA-
7 BI_DC+
8 BI_DC-

Following these pinouts, the wiring for a 1000Base-T crossover cord will look like shown at this link:

When making this crossover cord, please take into consideration that 1000Base-T standard states:
"Implicit implementation of the crossover function within a twisted-pair cable or at a wiring panel, while not expressly forbidden, is beyond the scope of this standard".

Best regards
Roman Kitaev, RCDD

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