[c-nsp] unwanted "arp reply" traffic at IX

[Chris Caputo]

We have two participants at our IX who are spewing out broadcast ARP 
"reply" packets onto the fabric.

In both cases, the participants are running Cisco routers that have 
customer ATM based DSL circuits on other interfaces.

"no ip mobile arp" an "no ip proxy-arp" on the ATM or IX facing 
interfaces have not stopped the apparent gratuitous ARPs.

Example packets:

--
02:54:23.499656 00:16:46:xx:xx:xx > ff:ff:ff:ff:ff:ff, ethertype ARP 
(0x0806), length 60: arp reply 208.x.y.z is-at 00:16:46:xx:xx:xx

02:58:12.711979 00:01:c9:yy:yy:yy > ff:ff:ff:ff:ff:ff, ethertype ARP 
(0x0806), length 60: arp reply 206.a.b.c is-at 00:01:c9:yy:yy:yy
--

IX ARP traffic should only pertain to the IX block, nor should there be 
any broadcast ARP replies on a regular basis.

Anyone one have any ideas on the best way to stop these?

Thanks,
Chris