[c-nsp] Ethernet autonegotiation issue between Cat3560 and Cat2960

[sthaug at nethelp.no]

> I have Catalyst 3560 and 2960 switches connected by a two member
> Etherchannel trunk using built in copper GE interfaces. For some reason
> Ethernet autonegotiation ends up assigning unmatching speeds for one link
> (10M in one switch, 100M in other) and the interfaces end up in suspended
> state.
> 
> MGMT-14#show int status | inc 35|36
> Gi0/35                       connected    trunk      a-full a-1000
> 10/100/1000BaseTX
> Gi0/36                       suspended    trunk      a-full  a-100
> 10/100/1000BaseTX
> 
> MGMT-13#show int status | inc 23|24
> Gi0/23                       connected    trunk      a-full a-1000
> 10/100/1000BaseTX
> Gi0/24                       suspended    trunk      a-full   a-10
> 10/100/1000BaseTX
> 
> Any ideas what might be causing this. I wonder if I'm running into some kind
> of minimum cable length problem. Switches are sitting adjacent to each other
> in a rack and connected with very short cables (0.5m ~ 2 ft).

There is *no* minimum cable length requirement for 1000baseT.

I would start by replacing the cable connecting the two suspended ports.

Steinar Haug, Nethelp consulting, sthaug at nethelp.no