02-13-2010 01:56 PM - edited 03-06-2019 09:42 AM
Well I am definitely a bit frustrated with this one.
My setup is a Catalyst (3560 C3560-IPBASE-M), Version 12.2(35)SE5,
I have a cisco phone with a PC behind it on port gi 0/40
port config
switchport access vlan 5
switchport voice vlan 105
Phone gets 105.x ip and PC gets 5.x ip. All is working well.
I am trying to sniff this traffic to ensure vlan tagging and QOS markings by using SPAN.
monitor session 1 source int gi 0/40
monitor session 1 destination int gi 0/3 encapsulation replicate
Can someone confirm that this is the correct config for this ?
Wireshark shows me entire phone conversation but I cannot see any 802.1q tagging..
I also tried to sniff int gi 0/49 as it is my dot1q trunk back to the core and I still cant see any vlan tagging..
Hoping someone can help me out on this one. I have read thru the docs and this should be a easy...
Cheers
Dave
02-13-2010 05:15 PM
Found the cause, it appears that the Nic driver and XP was stripping off the 802.1q info.
I ended up having to add a line in the registry under the NIC card settings.
Cheers
Dave
02-14-2010 12:52 AM
Hello Dave,
we had a similar issue some time ago getting different results with different laptops.
A useful explanation of how to capture vlan tags with wireshark is reported here:
http://wiki.wireshark.org/CaptureSetup/VLAN
It provides the methods to override the vlan tag stripping on windows based PCs (that are different depending on the NIC vendor)
Hope to help
Giuseppe
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