[c-nsp] Tuning HSRP timers for BGP routers

[Pete Lumbis]

A problem like this, especially on a software platform like the 7200
is ususally due to either small CPU spikes, local interface issues,
transit l2 issues.

Are the problems only in the evenings? Any backups that might be
causing traffic bursts or some sort of oversubscription in the
network?

Are you using the onboard NPE ports for the connectivity between the
peers or a PA? If so, which?

Do you see any STP changes on the transit switches?

Are you seeing any other control traffic issues, say BGP, OSPF or even
HSRP on other VLANs?

The only comment I'd have on BGP exhaustion is that with default HSRP
timers, BGP convergence, even with a large event, would (hopefully)
yield the CPU to other processes to allow for at least one HSRP packet
to get processed and keep the peers up.

I think the easy thing you can do is deploy CPU threshold logging
http://www.cisco.com/en/US/docs/ios/netmgmt/configuration/guide/nm_cpu_thresh_notif_ps6441_TSD_Products_Configuration_Guide_Chapter.html

This will give you notification at the 5 second level.

You can get tighter with EEM by setting an event trigger on the CPU
OID and then printing out whatever relevant information (i.e. "show
proc cpu sort" | append flash:eem.txt").

-Pete

On Wed, May 9, 2012 at 9:45 AM, Matthew Huff <mhuff at ox.com> wrote:
> We have a pair of Cisco 7204VXR with NPE-G2 running 15.1(4)M3. We are using
> default timers for the HSRP interfaces, and we are seeing nightly HSRP state
> changes. Not a lot, but 1-2 a night. This appears to only have started
> recently.  We are looking at logs, but I assume it's due to BGP cpu
> exhaustion. We don't see any L2 errors on the VLAN where the HSRP is
> running, so I don't think it's a physical problem.
>
>
>
> What timers do people use for HSRP on BGP routers as a practice?  Obviously
> we want the smallest timers that would be possible.
>
>
>
> ----
>
> Matthew Huff             | 1 Manhattanville Rd
>
> Director of Operations   | Purchase, NY 10577
>
> OTA Management LLC       | Phone: 914-460-4039
>
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>
>
>
>
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