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Gigabit port on 2950T-24 connection to 100 mbps port


we seem unable to interconnect a 2950T-24 via its 10/100/1000 port to a switch of an other supplier (Lucent). We do not have access to the Lucent switch, but the Cisco switch returns

"Uplink duplex mismatch" messages on this port at regular time intervals (several times per minute).

I suppose this has a severe impact on the traffic over the link, if it doesn't even shut down the link for user traffic altogether.

When trying to set the speed and duplexity of this port, the "duplex" command does not work.

It is not clear whether the Lucent switch supports speed/duplex negotiation.

What is the effect of the command "speed nonegotiate" ? Does this fix the speed at 1000Mbps (and full duplex) ?

I have suggested using a fast-ethernet port, and check the link capabilities using "show interface status", and then fixing the speed/duplexity setting on the 10/100BaseT ports (where speed and duplex commands are accepted).

How can we set the 10/100/1000BaseT port in such a way that it can become operational ?

Thank you


Re: Gigabit port on 2950T-24 connection to 100 mbps port

Autonegotiation is the preferred option. You should try this first. If that does not prove successful, you must assume that the other side has a fixed speed-duplex setting, which renders autonegotiation unuseable.

Try to fix the speed at 100Mb first, then set the duplex mode to full.

I must agree that strange things can happen when interconnecting 10/100/1000 interfaces.

To make a 3550-12G connect to an NM-1FE I once needed to set the speed to 100Mb on the 3550. With just that setting it autoconnects in Full duplex mode.



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