Catalyst 3550 port monitoring VLAN traffic

[keno44]

i have a vlan (vlan3) on which i need to monitor/scan for IM and P2P traffic. vlan3 routes to vlan4 which is the vlan closest to our firewall. i have set a monitor session to monitor vlan 3 (rx) and set its destination to the interface on which my packet analyzer sits. i have also been told that my dest monitor port needs to be set up on vlan4, again the vlan that sits closest to my firewall.

i have not yet began to see any traffic go to the monitor port. can someone suggest to me a reference which can walk me through some troubleshooting or provide a few troubleshooting techniques?

on a broadcast (hubbed) network, my packet analyzer does seem to work properly.

thank you for your help.

 

[paynenet]

You might Have the monitoring port in the wrong vlan !
Both the Source and Destination ports need to be in the same vlan !
so if you want to monitor port 1/1 in Vlan3 then the packet analyser/destination port needs also to be in vlan3.

Also on the 3550 the default for the span/monitor sess is uni-directional (rx only) by default. you need to add the both switch to the monitor comand (show port monitor ... should give the direction). I assume you are familar with the format of the span commande in 3550's in that you have to enter 2 commands 1 for source, 1 for destination.

Tip: If you are only interested in the P2P/IM to the external network I would monitor the firewall port as it is port span and will not contain the VLAN3 chat/internal network so buffers will be smaller.

http://www.cisco.com

online manuals is where I would look try entering the generic part of the command.