[c-nsp] Large number of arp entries on 2960G

[Geoff Falk]

Do you have any sort of default gateway set on the 2960G?  (ip default-gateway blah).  

The only time I've seen this on a L2 switch is when it doesn't have any L3 routing information, and as a result is just broadcasts an arp for everything remote, and the router answers via proxy-arp (@#$!*& Cisco and probably every other vendor for not making "no ip proxy-arp" a default on interfaces IMO) leaving all the remote IP entries with the local router's mac address in the arp cache.  

It does beg the question though why it's looking for all those IP's in the first place, though I suspect you need to answer that one anyway :).

Geoff


>________________________________
>From: John Elliot <johnelliot67 at hotmail.com>
>To: cisco-nsp <cisco-nsp at puck.nether.net>
>Sent: Sunday, October 2, 2011 7:09 PM
>Subject: [c-nsp] Large number of arp entries on 2960G
>
>
>Hi Guys,
>Running a management vlan(11) on a 2960S stack->2960G->7200 +  2509(for OOB) - i.e. 4 IP's
>sh arp on 2960s, shows 3 entries (int vlan11)sh arp on 2509, shows 3 entries (int eth0)sh arp on 7200, shows 4 entries(on dot1q vlan 11)sh arp on 2960g, shows over 1000 entries, all with the 7200's mac address, all on interface vlan11 - all entries appear to be "random" IP's, in that they are routes(IP's) learned from upstream bgp peering sessions and also some from our internal ospf...none of these bgp sessions or ospf are running in dot1q vlan11
>The only difference I can see on the 2 switches vlan interfaces is the 2960g(The one with all the strange arp entries) has "no ip route-cache".
>Any suggestions as to what could be causing this?
>Cheers.
>
>
>
>                          
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