[c-nsp] Cisco 6509 and ARPs

[Niels Bakker]

* rodunn at cisco.com (Rodney Dunn) [Fri 18 Feb 2005, 23:29 CET]:
> I can tell you that setting the arp timeout low with a large number of
> arp entries (2k in general or more) will possibly cause you problems.

Note that Internet exchange point operators strongly advise high ARP
timeouts, for exactly this reason:

> If your timers get in sync when you try and refresh you will drop
> packets off the input queue or the arp queue.  If you are going to do
> it bump up your input queue at least to be deep enough to hold at least
> one arp response from each machine on the segment.  That's sorta a
> worst case scenario.

Bigger exchange points (I know of LINX, AMS-IX) run "ARP sponges" to
answer ARP broadcasts for dead hosts on their LANs (e.g. disconnected
routers or people with an outage at layer 2).

Regards,


	-- Niels.

-- 
                              The idle mind is the devil's playground