[c-nsp] 6500 SXD7b VRRP issue

[Jon Lewis]

On Fri, 24 Apr 2009, Kevin Loch wrote:

>> all the interfaces on this router running VRRP started having their states 
>> change from backup to master to backup every few seconds.  After about 40 
>> seconds of this, it settled down and all the VRRP states went back to their 
>> original state.  While this was going on, the other 6500 participating in 
>> the VRRPs (which was the master) logged nothing and thought it was the 
>> master the whole time.
>
> This is likely a side effect of the cpu being maxed out, or encountering
> control plane rate limiting.  Was there something that spiked the cpu
> or exeeded your control plane limits that caused both the BGP session to
> drop and the vrrp flaps?  Loops on the switch that include cpu affecting
> packets (like vrrp for example) can easily do this.

It's not control plane rate limiting.  Because the BGP peer that went down 
was a transit peer (~280k routes), the CPU would likely have been quite 
busy dealing with the routing changes.

Do I need to tune process-max-time to keep VRRP from failing during 
periods of high CPU usage?  I don't think I've messed with that since 
AS5200s.


----------------------------------------------------------------------
  Jon Lewis                   |  I route
  Senior Network Engineer     |  therefore you are
  Atlantic Net                |
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