A duplex mismatch problem somewhere in the network can indeed cause problems for STP. It's an example of the infamous unidirectional link problem, which is also known as the one-way connectivity failure.
The side that is using full-duplex can send OK because it ignores the fact that the other side is sending at the same time. The side that is using half-duplex gets excessive collisions and gets so busy handling those that it can't send or receive frames reliably. So it doesn't hear BPDUs from the other side. This can result in it setting one of its ports into fowarding mode when it souldn't. Cisco has a feature to avoid unidirectional link problems. Try looking up their Unidirectional Link Detection protocol, although the real fix in this situation isn't to use the protocol, but, rather to fix the duplex problem, as you know. Priscilla Kenny Smith wrote: > > Hi.. I have one of my 2900 switch connected to my backbone > switch(5500). A > few day ago, I found that the switch to switch connection has > duplex > mismatch error. The 2900 sw interface was set to 100 full dpx. > But the 5505 > sw interface was set to auto neg, but they fail to negotiate > properly. > Therefore, I tried to set the 5505 sw interface to 100 full > dx. But > immediately after I set, the whole company network hang. All > users lost > connection for more than 10 minutes. > > I really can't understand why?? The 2900 sw has only one > connection to the > 5505 sw and both interface set to portfast (faststart) > disable. I think it > is related to spanning-tree but why spanning-tree loop will > happen in this > case. Can one explain to me. > > Thanks a lot > > > _________________________________________________________________ > Protect your PC - get McAfee.com VirusScan Online > http://clinic.mcafee.com/clinic/ibuy/campaign.asp?cid=3963 > > Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=60130&t=60090 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
