Re: OT: Which Gigabit ethernet card?

From: Eric Weigle (ehw@lanl.gov)
Date: Mon Dec 23 2002 - 12:23:57 EST

> > > Can I just use a standard Cross Over UTP cable to link up two Intel
> > > Gigabit card, just like Fast Ethernet does?
> > yes, but be careful, as cat 5e is pretty tough when it comes to the
> > connector specs
> I belive this is incorrect. A traditional ethernet crossover crosses two
> pairs, as ethernet & fast ethernet use 2 pairs. Gigabit ethernet uses all
> 4 pairs, and would need all 4 pairs crossed I assume.
According to spec, maybe, but in practice not necessary. Modern gigE cards
will run just fine over all sorts of pin-outs (even non-crossed over cables)

See
http://www.intel.com/network/connectivity/products/pro1000mt_desktop_adapter.htm

"automatically compensates for cable issues such as crossover cable, wrong
pin-out and polarity"

Or
http://www.intel.com/design/network/products/lan/controllers/82546.htm

"PHY detects polarity, MDI-X, 2 pair vs. 4 pair cables, and cable length
... No need to know the difference between crossover and non-crossover cables"

-Eric 

-- 
------------------------------------------------------------
        Eric H. Weigle -- http://public.lanl.gov/ehw/
"They that can give up essential liberty to obtain a little
temporary safety deserve neither" -- Benjamin Franklin
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