[nsp] High CPU utilization from traffic with no destination i nterface?

[Temkin, David]

Yup, I am running CEF...  There is no null interface because there's nothing
statically routed that way for it...

Show int switching shows that it's all being process switched.

-----Original Message-----
From: rpcbind at speakeasy.net [mailto:rpcbind at speakeasy.net] 
Sent: Thursday, June 26, 2003 2:35 PM
To: Temkin, David
Cc: cisco-nsp at puck.nether.net
Subject: Re: [nsp] High CPU utilization from traffic with no destination
interface?



Are you running CEF? If so, then there's an implicit adjaceny to the null 
interface, so it should be handled extremely inexpensively. What does a
'show 
ip int' of the ingress interface show -- any chance there's some features 
there that may have tickled things badly?


On Thu, 26 Jun 2003, Temkin, David wrote:

> Does anyone know the actual IOS architecture for handling packets that 
> enter the router where the router doesn't have a route for them?
> 
> I had a situation where a large amount of traffic was directed at one 
> of my routers that didn't have a route to the destination and the CPU 
> was pegged at 99%...  When I added an ACL blocking traffic to the 
> networks that I didn't have routes to, the utilization dropped 
> dramatically.
> 
> Thanks,
> 
> -Dave
> 
> 
> David Temkin
> S-I-G
> 401 City Avenue
> Bala Cynwyd, PA 19004
> http://www.sig.com <http://www.sig.com>
> 
> 
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