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

[Kasper Adel]

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a00800ef7b2.shtml

On Mon, Oct 3, 2011 at 4:28 AM, Geoff Falk <geoff_falk at yahoo.com> wrote:

> 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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> >
> >
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