packet sniffing a trunk link

Unanswered Question
Nov 18th, 2008

Hi all, If I set up a trunk with all my vlans on one port, if I use ethereal and plug into it, will I see all broadcasts etc for all vlans?

When using ethereal, am i right in saying it still works without an ip ?

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jedavis Tue, 11/18/2008 - 13:19

Hi Carl,

I believe that is true - you see all the traffic on all the Vlans. However, I think that span may strip off the dot1q headers so you don't know what vlan any particular packet came from. Set up a span/port monitoring session and give it a try. You have nothing to lose.

Ethereal (AKA Wireshark) does not even need the IP protocol bound to the monitor NIC.

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