Cisco - Nortel compatability

[Lybar]

I have a Cisco 2950 switch that I connect to another network that uses Nortel Baystack 420. I find that the Cisco switch will constantly show duplex mismatch. I have hard coded both switches to 100 full and the problem presets. Has anyone ever experienced a similar problem and how did you work around it?

 

[voltron1011]

You've double checked your crossover cable between the two? Usually, a faulty cable will cause issues like that.

 

[Lybar]

I haven't checked the cable but I've notice this problem when ever I've tried to connect Cisco to Nortel.

Thanks for the suggestion I'll try a new cable and see if that helps.

 

[vipergg]

If you have hardcoded both sides to a set speed and duplex you shouldn't have problems . Are you seeing errors on the ports . Sometimes cdp on the cisco switch will give a false reading on this error . Look for errors on either side , if its clean don't worry about the cdp error .

 

[jneiberger]

I disagree with vipergg. Set both sides to autonegotiate and I bet you the problem goes away. Let us know what happens.

 

[vipergg]

If you look at both sides and neither side is indicating errors then it is running ok , if the message is bothering you can turn off cdp on that connecting port and it will go away .

 

[jneiberger]

The CDP problem won't be an issue unless both sides run CDP, right?

 

[vipergg]

CDP is cisco proprietary for giving information on cisco attached devices on links , seeing that Nortel is not a cisco device it really doesn't matter if its on or off . Don't believe nortel runs cdp , the only other maker I know that does is Hewlitt Packard.

 

[jneiberger]

My point is that the CDP message you're referring to is caused by the exchange of link capability information between CDP-capable devices. If one device that uses CDP is set to half duplex and another CDP-capable device is set to full duplex you will get the message from CDP stating that it has detected a duplex mismatch. You won't get that particular message unless both sides participate in CDP.