[c-nsp] Tunnels on RSP720 / SRC

[Andrew Alston]

Hi All,

While I will be logging a tac case for this later today (had some 
problems doing so yesterday), I wanted to know if anyone else had 
noticed the following behavior:

I have a 7600 with dual RSP720 sups, running IOS SRC.  On the 7600 I 
have a tunnel interface (gre, though I tried IPIP as well).  Across that 
tunnel I have a full bgp feed.

 From the local router, I can ping the other end of the tunnel, no 
problems, however, the moment I try and actually route traffic through 
it, nothing flows.

After much playing around I discovered that IF you have an ACL on the 
tunnel interface, that permits all it does pass traffic, however, it 
*HAS* to be a logging access list.  If you dont have the log option in 
there, still no traffic.

This to me suggests that hardware forwarding is broken (I assume the log 
option causes punting to the CPU which allows the traffic to flow).

I also attempted to disable ip-route cache on the tunnel interface, but 
it didnt help (infact, no ip-route cache cef told me I couldnt do that 
on the platform)

Anyone else seen similar and have any other suggestions while I wait for 
TAC?  I'm currently redirecting my log files to /dev/null as a permit 
any log file on a tunnel running well over 100mbit produces a LOT of logs!

Thanks

Andrew Alston
TENET - Chief Technology Officer