SPAN not mirroring RX packets in Cisco CML.

[Mitrixsen]

Hello, everyone.

I have this topology here in Cisco CML and here is my local SPAN configuration with 2 L3 switches.

If I issue these two commands

SW2(config)#monitor session 1 source interface G0/0 tx
SW2(config)#monitor session 1 destination interface G0/1

SW2 mirrors any traffic that is transmitted from G0/0 and sends it towards G0/1. For example, here SW2 responds to SW1's ICMP Request. Since it's transmitting something out of G0/0, it mirrors it and sends it towards the PC that is running Wireshark

If I change the configuration to this:

SW2(config)#no monitor session 1 source interface G0/0 tx
SW2(config)#monitor session 1 source interface G0/0 rx 

It doesn't mirror anything received on that port at all, I was expecting to see ICMP Requests in Wireshark but they aren't mirrored.

Could someone please confirm this on real hardware? Is this a bug in Cisco CML or am I just misunderstanding something?

Thank you.

David

[balaji.bandi · Accepted solution]

Real hardware works—there is no issue with those commands. I have never tried them in CML 2.8 (I may test them when I get a chance).

Can you post the entire configuration of the span config?

[Mitrixsen]

Hello.

Thank you for taking your time to look into this! What I've posted here was the entire SPAN configuration, I've only tested those two commands where the RX option unfortunately did not mirror any packets in CML.

David