[f-nsp] [MLX-16] CAM lookup very slow

[Youssef Ghorbal]

On Sun, Oct 3, 2010 at 8:16 PM, Youssef Ghorbal
<youssef.ghorbal at gmail.com> wrote:
> Hello,
>
>  On a MLX-16, one of the Switch Fabric suffer from a very slow CAM
> lookup. When I issue a command like :
>  $> show cam ip 2/18 192.168.90.0 255.255.255.0
>  It takes nearly 2/3 seconds to have the prompt back. When it's
> instant on other modules. I don't have the problem on the same module
> when it comes to ethernet CAM.
>  This CAM lookup issue increases the network latency by a factor of
> 30. Ping RTT reach 30ms when it was 1ms in the past.
>
>  The Line Processor (LP) of the module seems to be beasy (beasier than
> the other modules)
>  LP-2#show cpu-utilization
> ... Usage average in the last 1 second  - 65 ...
> last 1 second  utilization = 65
> last 5 seconds utilization = 63
> last 1 minute  utilization = 66
> last 5 minutes utilization = 66
>
> on other LP :
> LP-1#show cpu-utilization
> ... Usage average in the last 1 second  - 1 ...
> last 1 second  utilization = 1
> last 5 seconds utilization = 1
> last 1 minute  utilization = 1
> last 5 minutes utilization = 1

I'll answer myself. After some digging with the Brocade support it
happens to be an ICMP redirect issue. We are in a situation of a
"single armed router" and The LP spends it's time sending/generating
ICMP redirects.

Plus, the issue have already been reported and treated on this list (a
while back)
http://osdir.com/ml/network.nsp.foundry/2006-12/msg00008.html

"$> no ip icmp redirect " did the trick for us.

Thanks all for your support.

Youssef