11-22-2010 04:24 AM - edited 03-06-2019 02:09 PM
Hi all,
I have a switch catalyst 3750 which runs spanning tree (MST).
The switch is connected via gige link to 3rd party equipment that can pass only L2 vlans , but not the RSTP BPDU.
I need a cisco command or configuration in which i could send the BPDU frames Tagged with specific vlan.
I tried to use MST , PVST but when i connected wireshark sniffer to teh gig ports , i noticed only untagged BPDU frames.
Is it possible with catalyzt 3750 ?
BR,
Yoram
Solved! Go to Solution.
11-22-2010 05:56 AM
Correct,
also check following link, how to make sure your PC will capture vlan-tags when using wireshark
http://wiki.wireshark.org/CaptureSetup/VLAN
Tom
11-22-2010 08:04 AM
hi all,
I managed to view the vlan tagg via wireshark after i updated the intel NIC via regeedit commands as appears in the link you have sent, thanks.
I have anotehr problem that when i connect the wireshark directly ro cisco STP ports i can view the packets , however when i configure the cisco with port mirror and pass the sniffer to the mirrored port but it seems the cisco mirrored port does not pass the frames .
any ideas
11-22-2010 11:35 AM
Hello Yoram,
as Tom and Jon have already noted the destination port of the monitor session has to be configured as a trunk port in order to see vlan tags of mirrored traffic.
Please note:
you can easily verify that PVST+ or Rapid STP BPDU frames are carried over the L2 transport service by using
show spanning-tree interface type x/y detail
where type x/y is the Cisco switch interface that acts as L2 CE node
you should be able to see a line called designated bridge ...
if there is communication both Cisco switches will agree on Designated Bridge bridge-id
if there is no communication each sides thinks to be the designated bridge/ DP for the link
This applies to each L2 Vlan permitted over the link
Hope to help
Giuseppe
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