Possible CARP routing issue

[Riaan Kruger]

Thank you for response.

I just found the problem. The third party software installs a route (the
second one listed in the above routing table) with the flags US and thereby
leaving out the G flag which states "Destination requires forwarding by
intermediary". This means that it assumes the destination is local and
therefor doing the ARP request


On Wed, Nov 26, 2014 at 8:24 AM, jd1008 <jd1008 at gmail.com> wrote:

>
> On 11/25/2014 10:46 PM, Riaan Kruger wrote:
>
>> 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
>> _______________________________________________
>> freebsd-questions at freebsd.org mailing list
>> http://lists.freebsd.org/mailman/listinfo/freebsd-questions
>> To unsubscribe, send any mail to "freebsd-questions-
>> unsubscribe at freebsd.org"
>>
>>  Did you enable forwarding?
> _______________________________________________
> freebsd-questions at freebsd.org mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-questions
> To unsubscribe, send any mail to "freebsd-questions-
> unsubscribe at freebsd.org"
>