mirroring ports in catalyst 29XX

Unanswered Question
Dec 4th, 2007
User Badges:


I read the folowing text.


I have a doubt.

When i make a SPAN, the statistics of show int are the same?


type configuration on fa0/5 port:



port monitor 1


clear counters

wait some for trafic in fa0/1

show int fa0/1

show int fa0/5

the output statistics of input and output packets, bytes, etc of int fa0/1 is the equal??

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
michal.grzelak Tue, 12/04/2007 - 13:58
User Badges:


Could you please give more details, which interface is the source of traffic and which destination?

Show counters may differ, whenever you are copying tx, rx or traffic in both directions.

Looking forward to hear from you.


Here is how I would set up your monitor session for sniffing a port.

monitor session 1 source interface Fa0/1

monitor session 1 destination interface fa0/5

That is assuming your sniffer is on port 0/5.

If you want to see if you are getting packets copied to inteface fa0/5 all you need to do is put a sniffer on there to see. It is also a good idea to have portfast turned off on your span destination and have it in a vlan that is not used ie. vlan 1.


This Discussion