Subject: How does the Master router respond to ARP request for a virtual IP address?

From: Rajesh Naveen <[email-masked]>
Date: Tue, 3 Apr 2001 19:57:33 -0700 (PDT)

Hi,

The RFC says "it is the duty of the VRRP Master router
to answer ARP requests for virtual IP addresses, and
it should send its virtual MAC in the ARP reply"

But how can this happen. Because the IP address
present in the ARP request need not be the router's
real IP address. If it is not the real IP, ie. when
the master is not the owner if the IP address in the
ARP request, then how will it respond to the ARP
request?

Thanks
Rajesh

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From: "Danny J. Mitzel" <[email-masked]>
Date: Wed, 04 Apr 2001 11:13:57 -0700

On Tuesday, April 03, 2001 at 19:57 PDT,

>> ARP request, then how will it respond to the ARP

this is all an implementation decision.  one alternative might
be when a backup router adopts an address to [temporarily] install
it as a local address.  then the router OS ARP code may work 
pretty much w/o change.  another alternative might be for the
backup router to dynamically instantiate a proxy ARP entry when
adopting address.  this also leads to minimal changes in router 
OS ARP code.  another alternative might be to augment the router
OS ARP code to be more aware of VRRP state and adopted addresses.
all of these, and other solutions, have advantages, disadvantages,
and interactions with other parts of VRRP specification and OS
operations.  the implementor must decide what tradeoffs are best
for their system.

danny