Unknown protocol drops on router interface

[mbroberson1]

Does anyone know how to best find out what "unknown protocol drops" are being dropped on a router ethernet interface. Initial packet capturing is not providing a lot in insight...so far.

Thanks,

Brandon

[Giuseppe Larosa]

Hello Brandon,

if another router is present and sends for example ISIS PDUs and the local router is not configured for ISIS the ISIS packets are discarded as unknown protocol packets because they are not IP packets.

if so this counter should increment one every 10 seconds in average

I've seen this in our network and I've found this explanation.

Hope to help

Giuseppe