[teddyh]

It was optional in 100Mbit. In gigabit, it is mandatory.

[reeses]

"Automatic MDI/MDI-X Configuration is intended to eliminate the need for crossover cables between simi-lar devices. Implementation of an automatic MDI/MDI-X configuration is optional for 1000BASE-T devices. The assignment of pin-outs for a 1000BASE-T crossover function cable is shown in Table 40-12 in 40.8."

Here's a link that does not require IEEEXplore access: http://www.scribd.com/doc/46141801/802-3ab-1999

[teddyh]

I say, I stand corrected. I was sure I read the opposite somewhere, but I would not dream of contesting your reference.