No arp entry, means router arps out to resolve l2 mac address of course No answer to first ping is common and I recently read that it has something to do with CEF throttling while it builds adjacency table entry
about the 5 minute arp timeout scenario....i believe that there is something within cisco ios that when the arp timeout period elapses, (and I believe it might be at half-life of timeout perios or something like that) that the router itself actually proactively arp's out even before real traffic is coming for that destination....in other words I think the router tries to reach out to the pre-existing arp entries to see if they still exist at arp timer halflife or something like that. I think I saw that while doing "debug arp" or something like that one day a while back aaron -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Lee Sent: Monday, January 21, 2013 12:23 PM To: [email protected] Subject: Re: [c-nsp] unknown unicast flooding - particularly regarding fhrp's On 1/21/13, Aaron <[email protected]> wrote: > 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 What happens when the router doesn't have an arp entry? When I ping an idle host I don't get an answer to the first ping. So if you set the arp timeout to 5 minutes does that mean the 1st packet to a host that's been idle >= 5 minutes is dropped? Thanks, Lee _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/ _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
