[c-nsp] GRE Tunnels and vrfs

[Mihai CHELARU]

Gert Doering wrote:

>>Question 2: Why is this setup working after I disable CEF ?
>>    
>>
>
>How exactly is this "not working" with CEF?
>
>  
>
tcpdump shows that nothing is routed through this tunnel so packets are 
just black-holed. I checked the routes in RIB and they appear to be OK. 
A simple 'no ip cef' solves it. I think I'll update IOS these days and 
see how it does ;/

>There are lots of funny bugs in GRE tunneling with CEF regarding TTL 
>decrementation (TTL not being decrement -> router not visible in 
>traceroute, and worse, if you have a loop, the packet will loop forever, 
>burning CPU like mad).
>  
>

Yes, I saw this too on other tunnels that I use but it's not so disturbing.