[c-nsp] HSRP Flapping Due to CPU Spikes

[alaerte.vidali at nsn.com]

Hi Gianluca,

Thanks for your information. (sorry the delay between one message and
other, out of office)
I think this may be a central point of the instabilities we are
observing on 7600. I am trying to understand why ""mls rate-limit
unicast ip icmp unreachable..." help in your case.

Please if you have time let me know:

-Did you use commands to verify mistral asic drops?
-Is the traffic punted to RP data traffic? 
-Are you using logging on Access Lists?



Tks,
Alaerte  

-----Original Message-----
From: ext hjan [mailto:hjan at libero.it] 
Sent: Thursday, June 14, 2007 7:04 AM
To: Vidali Alaerte (NSN - BR/Rio de Janeiro); cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] HSRP Flapping Due to CPU Spikes



alaerte.vidali at nsn.com ha scritto:
> Hi Gianluca,
> 
> Did you have a clue why does rate-limit solve the problem?

In my case it is a combination of multiple factor, network topolgy and
routing/qos design, however with mls rate-limit unicast ip icmp
unreachable acl-drop 0 you force the SIP601-LC to doesn't punt
unreachable packet to SUP-720 for processing,  so you can't overwhelm
the CPU.
In my case for a short time after the up/down on tenge the cpu was
overwhelmed and drop on mistral asic occours, what you drop is random
and in my case involved eigrp.

A sniff of the pachet punted to RP helped me a lot :) :
monitor session 1 source interface gx/y
monitor session 1 destination interface gx/y remote command switch test
monitor add 1 rp-inband tx


Regards,
Gianluca