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802.1q troublshooting

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Hello I have a Mikrotik router trunked to a an ESXi server. The trunk port is setup according to VMware and MikroTik, but I can not ping across. I would like to capture the trunking traffic, but not sure how to filter it to see what is going on and try to diagnose the problem.

I would like just to see only the 802.1q protocol and not the rest of the traffic trying to get across, or any other troubleshooting tips that can help me troubleshoot this problem.

thanks

asked 01 Jun '14, 15:39

mrjoli021's gravatar image

mrjoli021
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edited 01 Jun '14, 15:41

One Answer:

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I would like just to see only the 802.1q protocol, and not the rest of the traffic trying to get across

There is no 802.1q 'protocol'. 802.1q simply adds tags to a frame to mark the vlan it belongs to. So, it does not make sense to capture only the VLAN tags, without the rest of the frame (if I understand your question in the right way).

So, here is what I would do:

  • start a packet capture on the mikrotik (see the manual), without any filters
  • configure a mirror port on the switch that connects the mikrotik and the esxi server. Capture any traffic on the port that the esxi is attached to.
  • limit the capture size in Wireshark/tcpdump to 100 bytes (-s)
  • ping in either direction
  • stop the packet captures
  • analyze the files with Wireshark

BTW: If you want to see only VLAN traffic, you could use the capture filter: vlan, however that does not make much sense on a trunk port of the switch, as almost all frames will be tagged.

Regards
Kurt

answered 01 Jun '14, 16:09

Kurt%20Knochner's gravatar image

Kurt Knochner ♦
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accept rate: 15%

edited 01 Jun '14, 16:31