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Cisco MSTP

I'm attempting to setup a cisco 3020 blade switch at a remote site connecting back to a cisco 4506. The 4506 has MSTP setup. The link (which is a point to point LES link) between the switches is set up on both switches as a 802.1q trunk. I have setup the 3020 with all the MSTP region info so when it is connected to the 4506 it should change its MSTP state to point to the 4506 as the root. However they don't seem to talk to each other ie exchange BPDU's. I can ping between switches and telnet etc so the link is functioning, but if i do a sh span mst command the 3020 is the root and so is the 4506. Doing a sh span mstp int g0/17 (the uplink port) on the 3020 shows the 3020 is sending BPDU's but not receiving any, doing the same on the 4506 switch shows it is also sending BPDU's but not receiving any. It is as if the BPDU's are disapearing across the link!

Has anyone come across this or have any ideas?
1 Solution
Don JohnstonInstructorCommented:
Going to need to see the configs.
nappyshockAuthor Commented:
Thanks for replying Don, the fault has now been resolved. It was caused by the point to point 1Gb telecom LES line. I've never seen that problem before it is supposed to be a clear layer 2 link and was communicating fine except for the spanning tree the telecom provider said there was no problem with it. I proved it by taking the remote switch back to the main site and plugging it in directly and it all worked fine. With this proof i spoke to the telecom provider again and guess what, half an hour later it was all working properly.
I had only spent a day and a half with an irate customer trying all sorts of config changes almost going mad thinking it must be my setup as i had not worked on the 3020's before.
I hope this info prevents some else in the future going through the same thing.
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