[c-nsp] high CPU utilization and GRE tunnels on Cisco 2800 series ISR

[Lukas Tribus]

> interface Tunnel0
> bandwidth 10000
> ip unnumbered FastEthernet0/0
> tunnel source FastEthernet0/1
> tunnel destination 10.10.10.195
> tunnel key 10213
> tunnel checksum
> tunnel path-mtu-discovery
> end
>
> Ass five(Tu0 - Tu5) GRE tunnels configured to this router have similar
> configuration with exception that some have "ip mtu" or "keepalive"
> configured.
>
> Has anyone seen similar behavior before?

I strongly suggest to disable "tunnel checksum", because this will
bypass CEF and you end up process switching everything (a part from
the fact the the actual checksumming takes it toll as well).



Regards,

Lukas