PKTC 175 Unknown KMMID 0x4d

Hello folks,

I'm troubleshooting a network problem at a school and I'm having difficulties finding the problematic node. It seems as if there's a node that's causing the spanning tree protocol to restart every ten minutes, leaving the entire network completely dead for half a minute in the process. At least this is my gathered info from talking to several network techs and HP support.

Trying to analyse the traffic isn't easy in my book, and no matter how many times I've used Wireshark and tried to understand the logs, I don't have the education to fully understand what each line means. Hence I need your help.

There's particulary one line that I don't understand, and can't seem to find any info on. It's this line:

1700 90.108443 10.0.50.240 239.255.255.250 PKTC 175 Unknown KMMID 0x4d (Unknown DOI 0x2d)

Does any one know what this means?

Here's the log that captures the error: http://linford.se/temp/net_log.pcap

And here's more info about the problem and our troubleshooting: http://communities.vmware.com/message/1905462#1905462