Date: Wed, 26 Nov 2014 09:31:38 +0200 From: Riaan Kruger <riaank@gmail.com> To: jd1008 <jd1008@gmail.com> Cc: freebsd-questions@freebsd.org Subject: Re: Possible CARP routing issue Message-ID: <CABNwDi067MrMQk9x5=3fjC-jmKC7tioCxFOM6P2bKBvQ-5-LhA@mail.gmail.com> In-Reply-To: <54757216.5090502@gmail.com> References: <CABNwDi0LiEueW%2BU9jypPGvtSxYqShSLZZNnpT1b1oRc-f=DTZA@mail.gmail.com> <54757216.5090502@gmail.com>
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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@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@freebsd.org mailing list >> http://lists.freebsd.org/mailman/listinfo/freebsd-questions >> To unsubscribe, send any mail to "freebsd-questions- >> unsubscribe@freebsd.org" >> >> Did you enable forwarding? > _______________________________________________ > freebsd-questions@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to "freebsd-questions- > unsubscribe@freebsd.org" >
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