Multiple ARP entry question

[k.aumell]

I've just installed 19 new 2702 APs, and for reasons I can't figure out, my core switch can't settle on an ARP entry for any of them. My core switch is also the DHCP network for this vlan (253).

For example one APs ARP entries look like this:

Internet  172.27.252.26           4   d8b1.9016.4474  ARPA   Vlan253
Internet  172.27.252.54           3   d8b1.9016.4474  ARPA   Vlan253
Internet  172.27.252.113          2   d8b1.9016.4474  ARPA   Vlan253
Internet  172.27.252.161          1   d8b1.9016.4474  ARPA   Vlan253
Internet  172.27.252.209          0   d8b1.9016.4474  ARPA   Vlan253
Internet  172.27.253.12          10   d8b1.9016.4474  ARPA   Vlan253
Internet  172.27.253.66           9   d8b1.9016.4474  ARPA   Vlan253
Internet  172.27.253.158          8   d8b1.9016.4474  ARPA   Vlan253
Internet  172.27.253.175          7   d8b1.9016.4474  ARPA   Vlan253
Internet  172.27.253.194          6   d8b1.9016.4474  ARPA   Vlan253
Internet  172.27.253.237          5   d8b1.9016.4474  ARPA   Vlan253
 

None of those addresses answer to ping.

A "show cdp n" on the switch the APs are attached to looks like this:

APd8b1.9047.4474 Gig 1/0/1         140              T B   AIR-CAP27 Gig 0
 

The rest of my LW APs look like this:

AP70ca.9b99.0179 Fas 0/24          162           R T      AIR-CAP35 Gig 0.1
 

The "T B" designations vs. the "R T" designation is interesting as well.

Any ideas on where to start?

Thanks

Kyle

[cmlozano8]

It looks like something else is replying to the arp requests.  WLC?  When you try to ping you sending it to that device and it is not replying.

[k.aumell]

I don't *think* it's the 5508 replying to the arp requests. It could be something else, though. I may need to get on the console of one of the misbehaving APs and see if I can pick anything up from there.

[Richard Burts]

Note that all of the ARP responses come from the same MAC address. Trace that MAC address through the switch forwarding table and you may be able to find the device that has this MAC address.

I was looking at an issue very similar to this in a customer network recently. We traced it back to some device (in their network a switch) that had proxy arp enabled and was sending ARP responses for IP addresses that did not really exist in the network. Sounds similar to what you are describing.

HTH

Rick