Just as a rule of thumb, if you use any of Cisco's newer switches, including the 2950, it's best practice not to hard-set your speed and duplex unless you know for certain that the device you're connecting does not support autonegotiation. Here's the short explanation of why it _might_ be failing in your situation:

When you hard-set these settings on the 2950, autonegotiation is completely disabled. However, many devices still participate in autonegotiation even when their settings have been set manually. They would simply only offer their manually configured settings as being available. If that type of device is manually configured for full duplex but it does not detect an autonegotiating device on the other end, it will assume that it is connected to a hub and will drop back to half duplex regardless of the configured settings.

It's possible--and I see this a LOT--that the device being connected still participates in autonegotiation despite being manually configured for 10/Full. I know from experience (we have a lot of them) that the 2950 disables autonegotiation completely. Fixing duplex mismatches caused by this problem used to be a daily occurrence for me. It's now only a weekly occurrence. :)

If you want to do a quick test, remove your manually configured settings and see what happens. If the other side is still participating in autonegotiation, there's no reason not to let it work as intended. If your errors clear up, you'll know what the problem was.

Regards, John

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I have seen a 2950G-48 port connected to a Packeteer 4500, both set to 100 Full Duplex not work duplexity out correctly. I have seen the same happen between an Enterasys E-7 blade and a different 2950.

In both cases an update on the other device "fixed" the Cisco switch.

John Exum Network Manager Harding University