Date: Mon, 21 Nov 2005 15:02:17 +0300 From: Gleb Smirnoff <glebius@FreeBSD.org> To: Kazuaki Oda <kaakun@highway.ne.jp> Cc: freebsd-net@FreeBSD.org Subject: Re: gratuitous ARP from CARP backup host Message-ID: <20051121120217.GQ24212@cell.sick.ru> In-Reply-To: <4381B26B.6080407@highway.ne.jp> References: <437F4D18.9030003@highway.ne.jp> <20051121111717.GO24212@cell.sick.ru> <4381B26B.6080407@highway.ne.jp>
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On Mon, Nov 21, 2005 at 08:41:31PM +0900, Kazuaki Oda wrote: K> >On Sun, Nov 20, 2005 at 01:04:40AM +0900, Kazuaki Oda wrote: K> >K> I reported a problem a few days ago that CARP backup host replies ARP K> >K> request. This problem has been fixed, thanks. But I found one more K> >K> problem. K> >K> K> >K> 1) master host and backup host are connected to the same layer 3 K> >K> switch. K> >K> K> >K> 2) at master host, I run the following command: K> >K> # ifconfig carp2 create K> >K> # ifconfig carp2 vhid 22 advskew 10 pass xxxx 192.168.1.7/24 K> >K> K> >K> 3) master host sends gratuitous ARP. K> >K> K> >K> 4) at backup host, I run the following command: K> >K> # ifconfig carp2 create K> >K> # ifconfig carp2 vhid 22 advskew 100 pass xxxx 192.168.1.7/24 K> >K> K> >K> 5) backup host sends gratuitous ARP. K> >K> And so, layer 3 switch sends packets addressed for 192.168.1.7 to K> >K> the port connected to backup host, sigh... K> > K> >Does it sends packets until next advertisement from master or forever? K> K> Forever. K> Master host never receives the packets. Well, I'm afraid I will just answer that your L3 switch is stupid, if it builds its FIB based only on ARP packets. The correct behavior IMHO would be to correct FIB on every packet with given IP address as src. Since master continously sends the CARP announcements, the FIB of the switch should be corrected in next second. -- Totus tuus, Glebius. GLEBIUS-RIPN GLEB-RIPE
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