[c-nsp] Negotiation problem with Catalyst 2950 and Cisco 2821

[Matthew Stainforth]

Avaya PBX cards such as medpros and CLANs seem to be bad too.  With both sides set to auto/auto, autoneg settles on a duplex mismatch (half on avaya, full on cat2950) more often than not.  There's not much choice but to hard set both ends to 100 full.  Or, if there is a better choice (besides righteous indignance) I'd like to hear it.


-----Original Message-----
From: Gert Doering [mailto:gert at greenie.muc.de]
Sent: Saturday, December 03, 2005 6:01 PM
To: John Neiberger
Cc: C. Jon Larsen; cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] Negotiation problem with Catalyst 2950 and Cisco
2821


Hi,

On Sat, Dec 03, 2005 at 12:51:26PM -0700, John Neiberger wrote:
> We have the opposite philosophy. We set everything to auto. We have
> *far* more problems with hard-set switch settings. It's been my
> experience--and I have documentation at work to back this up--that
> hard setting your devices to 100/Full is the worst possible choice.

Yep.  Before long, the customer will change *something* (like "upgrade
his NIC drivers", or "replace switch with different one") and his side
will revert to auto-neg.

Fairly inevitably, it will then go to half-duplex ("my peer doesn't do 
autoneg?  Must be a dumb hub, go to HD"), and the fun begins.

We've recently changed lots of 100/full-hardwired ports to auto/auto
(leading to a-100/a-full) due to lots of port errors reported by the
switch... and voila, all errors gone.

For some combinations, especially to Cisco *routers*, manually setting
100/full is required, as the PA-FE-TX (for example) just doesn't do
autoneg.  But this is becoming the exception, not the rule, these days.

gert

-- 
USENET is *not* the non-clickable part of WWW!
                                                           //www.muc.de/~gert/
Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de
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