Have to run auto-negotiate between clients and switch - "old" switch works fine - "new" switch results in "port flapping"?

Posted by ConfusedAboutSwitching on Server Fault See other posts from Server Fault or by ConfusedAboutSwitching
Published on 2012-10-21T05:09:13Z Indexed on 2012/10/21 11:04 UTC
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I need some help understanding a problem we're having at work: We run Altiris/Deployment Solution and have to use auto-negotiate between client systems and our switches (Altiris apparently requires this for imaging, PXE boot and other functions). We have several areas with old wiring (Cat 3 & Cat 5) that have old 10/100 Cisco switches in them - and we can set these systems up to "auto/auto" (auto-negotiate on both the NIC and the switch port), and everything has been working fine. But - our networking crew changed out a couple of old switches for 10/100/1000 Cisco switches, and now - they are claiming that "auto/auto" won't work because the switches can't auto-negotiate the way the old 10/100 switches did - and that if we try to set the new gig switches to auto-negotiate, the switch port starts "port flapping", and shuts the port down. But - if we put the old switch back in - they work using "auto/auto" just fine - no port flapping. The networking crew is telling me that the problem is that we're putting "new switches" on "old wire", and that the old cabling can't/won't support the auto-negotiation with these new switches....???

There's something about this that doesn't make sense to me - can someone explain this to me? Or is our networking crew just doing something wrong in the configuration of these new switches? While will the old switches work "auto/auto", but the new switches won't??

HELP!!....and Thanks!!

M

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