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QuickBite : Verifying VLAN Tag using Wireshark CLI (tshark)

If you want to verify the flow of packets from a VM (which is connected to a OVS) to a Switch and ensure that they are getting tagged properly, you can follow the process mentioned below:




Step 1 : Are packets getting sent over eth1


Looks good. We can see that packets are getting sent over eth1.

Step 2 : Check if packets are being received on ge-0/0/10


Looks good. If you see that packet count is not increasing on the interface, it may be because the corresponding VLAN is not associated with that interface (or the packet is being sent with out the VLAN tag)

Check ge-0/0/10 configuration:



Looks good.

Step 3 : Lets check if packets are getting tagged when sent over eth1

[I have Wireshark installed on CentOS. Am using the Wireshark CLI as my server does not have gui installed on it]



Done. You are now ready to trouble shoot basic packet flow.

A few other commands that come in handy on a VM are:
  • To check the routes known to the system : route -n
  • To check the arp table : cat /proc/net/arp
  • Ping a system over a specific interface :  ping -I eth1 ip-address

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