2 KNE100TX cards, no hub/switch, options= ?

Donald Becker becker@scyld.com
Fri Apr 28 03:55:55 2000

On Wed, 26 Apr 2000, Eric Jorgensen wrote:

> > Neither.  You should allow autonegotiation to take place.  Read
> >   http://scyld.com/expert/NWay.html
> > forcing either the speed or duplex will prevent autoenegotiation.
> 	I agree with you, to a point, and I do not wish to contradict you. But
> autonegotiation (not related to linux in any way) has caused me a great
> deal of BS lately. 
> 	Example: Cisco Catalyst switches and 3Com SuperStack II switches, when
> network utilization is fairly high (over 30%), fail to autonegotiate to
> full duplex. This caused me several hours of BS just this week. 

Sigh.  Those switches are broken.  It is sad that the two largest names in
the industry both produced broken hardware a few years ago.  And I don't
mean "broken" in the gentle sense of making non-optimal technical
decisions.  They just flat out had a flawed hardware design.  They tried to
cover up by spreading the FUD that autonegotiation was bad and that
everyone should force the speed and duplex, even while their smaller
competitors (almost everyone else in the industry) had perfectly working

Their current products do work with autonegotiation.

> 	Example: Xedia AccessPoint 100 CBQ bridge/router units aparantly only
> autonegotiate with other AccessPoint units, or something. Xedia
> technical support was initially baffled by my accusation that their unit
> would not negotiate full duplex no matter what it was connected to, and

Use 'mii-diag -w' to see what is occuring.

> then later admitted that the only way their unit will negotiate to full
> duplex is if the device the AP100 is attached to is already in full
> duplex mode when it connects - ie, has been forced to full duplex. 

Ehhh?  If you force 100baseTx or full duplex, you *cannot* do
autonegotiation.  The closest you can get is to advertise only full duplex
media types.  I think they were feeding you a line..

> 	If it doesn't work with a crossover cable, it might be a bogus cable,
> try a different cable. You might have bogus nics, too. 

"It can't be mispaired, I made it myself."
Cat5 pairing is *not* intuitively obvious.  Most people should not be making
their own cables.

Donald Becker				becker@scyld.com
Scyld Computing Corporation
410 Severn Ave. Suite 210
Annapolis MD 21403

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