Possible CARP routing issue

[Riaan Kruger]

It seems that in some circumstances routing is not playing well with CARP.
We have the following scenario.

Device A
---------
192.168.1.10

Router:
-------
10.0.0.1

Device B
--------
Interface 1 Virtual IP (CARP): 172.16.1.3
Interface 1 Real IP: 172.16.1.2

Routing table of device B:
0.0.0.0        10.0.0.1
192.168.1.0    10.0.0.1
etc ...

When Device A pings the Real IP of Device B (172.16.1.2) we see the
following ARP request packet:
ARP request who has 192.168.1.10 tell 172.16.1.3

In other words pinging the real IP causes the Virtual IP to ask for the MAC
address of the pinging device, even though they are not in the same subnet
and there is a default route. Pinging the virtual IP does not induce this
ARP request and the ping is successful.
When deleting the second route from the routing table above the ARP request
is not sent.
I know the second route is superfluous but it is put there by third party
software.

The real issue is why this behavior happens with CARP. Is it an indication
of some underlying problem?


Riaan