Capture packet Cisco 1811

[Mehdi Talei]

Hello,

I would like to capture the data on one of the WAN interfaces of 1811. I am not sure if it is possible to do that with a router, but I see the command monitor session. When I execute :

monitor session 1 source interface fastEthernet 1

it gives me the error :

% Invalid input detected at '^' marker.

Any idea what the problem can be?

Thanks

[Mehdi Talei]

I actually found the answer why it does not work with Fa0 and Fa1. Because they do not have switching characteristic.

But what is the best way to capture the data on these two WAN interfaces?

Thanks