[nsp] Unknows Packets on WAN Port

[Mark Kent]

>> We have Cisco 2501 Router installed and configured. Recently, I found =
>> there is unknown bandwidth occupying the Router's WAN port. Where as the =
>> Router's Ethernet Port has no utilization at all.=20

Is the input usage roughly equal to the output PPS?
If so, it is probably traffic looping around until the TTL
expires and the packet gets dropped.

That is, the far end believes x.y.z.w is at your side of the 
WAN, and you believe the same net is at the far end.  
Then, any traffic coming in destined for x.y.z.w  will just
loop around and around.

A quick way to see what the traffic is is to
turn on "ip accounting" then "sh ip account" will
reveal the culprits.

-mark