Sniffing a router FastEthernet port

[mulhollandm]

Folks

I have a 2621xm with 2 FastEthernet interfaces one of which is connected to a backbone network i subscribe to. The second interface connectes into my LAN

My problem:

i can see a constant 2.5Mb of traffic coming into my connection to the backbone (the traffic is coming from the backbone)

but when i monitor my LAN interface i can see the traffic isn't making its way into my LAN

i have looked at the number of broadcasts on each interface and this is pretty low so the 2.5Mb is'nt broadcasts

My query:

does anyone know of a product, either free or reasonably cheap i can to use to look a t the traffic hitting each of my ethernets?

my thanks to anyone taking the time to respond

thanks for your help and suggestions!

[smif101]

Are you running BGP with the backbone network? If you disconnect the LAN connection to the office on the router does the traffic go away?

[mulhollandm]

the backbone belongs to a third party but it know it runs ospf, rip, eigrp amongst others

the office is on a remote site but i'll try your suggestion first thing tomorrow

thanks for your reply

[s.uslay]

if you have a hub( or low end switch and use span function), you can use

Ethereal (free) to look at the traffic on the backbone interface first then move it to internal interface and compare.

Serhat