AS/400 9404 and TWINAX questions...

From: Paul Koning <pkoning_at_equallogic.com>
Date: Tue Sep 28 08:19:07 2004

>> Good news: You could even make an Ethernet/Twinax single jack, if
>> you're not running faster than 100Mbps ethernet, as they run 1/2 &
>> 3/6 for their pairs -- just use 4/5 for twinax.
>>
>> Bad news: *Most* pre-built cables don't follow the standard as to
>> where the twisted pairs should be - most just go 1/2 - 3/4 - 5/6 -
>> 7/8 - and that's bad for both Ethernet & twinax. You'll wanna
>> punch down and/or build your own cables if you're going to do
>> this.

Telephone cords would be wired that way, but I have NEVER seen
commercially made network cables miswired. They ALL have 3/6 paired,
as required.

I saw a miswire like you describe only once -- in a home-made test
cable. Our lab had a 100 meter Cat 5 cable for router testing.
Unfortunately, it was miswired, so it had lots of crosstalk -- which
made it seem that our router's Ethernet interfaces were misdesigned.
When I finally figured out what was wrong, I grabbed cutters and cut
off the connectors so no one could use that cable until we got it
fixed...

The one thing you do have to watch out for is straight through
vs. crossover cables (for 10/100 BaseT). Straight through goes to
hubs, crossover is if you connect one PC to another. With GigE it
doesn't matter, just use straight through in all cases.

        paul
Received on Tue Sep 28 2004 - 08:19:07 BST