Gratuitous ARP

[Jay Ford]

On Mon, 17 Feb 2014, Alex Bligh wrote:
> It's a while since I looked at the proxy ARP RFC, but I /thought/ you were
> not meant to proxy ARP for IP addresses that you would reach through the
> same interface you received the ARP request on. Else a device with
> proxy ARP on would ARP for everything on its subnet. This suggests
> this is misconfigured proxy ARP, for instance sharing a L2 broadcast
> domain with proxy ARP on, but not having all IP address ranges configured
> (and hence reaching some of them through a default route).

Sure, but wireless access points & especially controller-based wireless 
systems like to bend & break such rules in the interest of optimizing traffic 
on the RF-based nets they create.

We seem to have a similar situation going on here with IPv6 DAD failures due 
to AP/controller proxy responses to neighbor discovery packets, although it's 
still under investigation.  Great fun!

________________________________________________________________________
Jay Ford, Network Engineering Group, Information Technology Services
University of Iowa, Iowa City, IA 52242
email: jay-ford at uiowa.edu, phone: 319-335-5555