I have two 2811 routers with a 2960 switch in between setup for port mirroring.
R1 <==> SW <==> R2
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Mirror Port
The R1 FE0/1 port is connected to the 2960 port FA0/1
The R2 FE0/1 port is connected to the 2960 port FA0/2
I have a computer running wireshark attached to the 2960 GE0/1 port
My 2960 was reset to factory default and then I setup the following mirrors.
# monitor session 1 source interface fastethernet 0/1
# monitor session 1 source interface fastethernet 0/2
# monitor session 1 destination interface GigabitEthernet 0/1
I am using this setup to experiment with different routing protocols.
So far, I am able to see routing messaging exchanges on the mirror port for RIPv2, EIGRP, OSPF and ISIS (L1 and L2) between R1 and R2.
I have also setup and got BGP working with traffic (i.e. pings) passing through R1 and R2 and show ip bgp at both routers displays the correct AS associations.
However, I see nothing in the wireshark capture, neither with wireshark filter: bgp, or with filter: tcp.port==179 or with no filter at all.
Is the 2960 mirror blocking BGP messaging ? Am I missing something ?