[c-nsp] unknown unicast flooding - particularly regarding fhrp's

[Aaron]

Arp timers are central, bridge timers are more distributed

Arp timers I believe are specific to svi/bvi/routed interfaces, bridge
timers I believe are more global and may not be vlan specific

Those 2 items would lead me to think arp timers would be the best place to
adjust

Thanks

-----Original Message-----
From: Mikael Abrahamsson [mailto:swmike at swm.pp.se] 
Sent: Monday, January 21, 2013 11:18 AM
To: Aaron
Cc: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] unknown unicast flooding - particularly regarding
fhrp's

On Mon, 21 Jan 2013, Aaron wrote:

> How does constant unknown unicast flooding affect networks?  Better 
> yet, how to design in mitigation ?  is it all about lower arp timeouts 
> below
> 300 secs so to artificially prop-up bridge tables and keep them fresh? 
> My goodness that's making arp very busy.

Make sure your arp timeouts are aligned with your bridge timeouts (keep arp
timers lower than bridge timeouts). Easiest way to do it is (as you
say) lower arp timers. Another way is of course to raise bridge timeouts.

-- 
Mikael Abrahamsson    email: swmike at swm.pp.se