How to check port mirroring is working or not?

Unanswered Question
Jun 25th, 2009

How to check port mirroring is working or not?

It was configured like this

monitor session 1 source interface Gi2/10

monitor session 1 destination interface

Gi2/9 ingress vlan 1

what does this indiacets?

I have this problem too.
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Giuseppe Larosa Thu, 06/25/2009 - 23:50

Hello Vinoth,

you can check with

sh monitor session

source port is Gi2/10

destination port is Gi2/9 the option ingress vlan1 is more specific

ingress should stand only for the inbund direction on the source port and frames in vlan1.

I tried to look at the command reference but I didn't find this option listed.

What platform and IOS image are you using ?

Hope to help


vinothlb1 Fri, 06/26/2009 - 00:26

I have given the sh monitor session but how to know port mirroring it is working or not.. Is there any link pls provide..?

pompeychimes Sun, 06/28/2009 - 22:30

Look at the device (Sniffer, IDS, etc...) to which your mirroring traffic to.

cisco_lad2004 Fri, 06/26/2009 - 12:16

I concur with James, the only way you are 100% positive is:

1-Check your sniffer is receiving data.

2-Even when you see data, remove SPAN port config to make sure the data you see on sniffer is your session (I usually shut the port I am spanning if its not service affecting). The reason is that I have seen that sometimes sniffer is getting all sort of junk you are not really spanning for, especially when using ERSPAN.



Pushpendra Yadav Thu, 07/25/2013 - 10:55

install Wireshark on your system. Connect laptop on span port and then start capturing Span port traffic. If you see traffic coming from mentioned source then it is working fine.


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