12-14-2008 11:41 AM - edited 03-04-2019 12:42 AM
Cisco 7600 is connected with routed port on OSM module to a switch. Network behind the switch experiences L2 loop and STP goes crazy. This kills CPU on Cisco 7600. I would like to know is there a mechanism to prevent this behavior. How does Cisco 7600 treat STP BPDU that comes in on a routed port?
12-15-2008 01:38 AM
Hello Davor,
on a routed port STP BPDUs should be ignored.
But in your case the C7600 cpu goes high and STP is among the processes using more cpu if I understood correctly your post.
I suppose you have checked this with
sh proc cpu sorted
During the L2 loop there are also an high level of broadcast frames ?
Hope to help
Giuseppe
12-15-2008 01:51 AM
Well, I didn't have access to the box at the time of problem. All I could see was output from #sh proc cpu history and the fact that all routing protocol adjacencies were broken at that time. I'm not 100% sure what happened but I know that there was stp loop on that side. I wouldn't count that there were a lot of broadcast frames because there is only one other host on this Vlan.
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