Date: Sun, 1 Sep 2019 21:10:47 +0700 From: Victor Sudakov <vas@mpeks.tomsk.su> To: freebsd-net@freebsd.org Subject: Re: Several IPv6 routers and default gateway choice Message-ID: <20190901141047.GA56954@admin.sibptus.ru> In-Reply-To: <20190830.121543.1108900942284640156.hrs@allbsd.org> References: <20190830021228.GA66465@admin.sibptus.ru> <20190830.121543.1108900942284640156.hrs@allbsd.org>
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--PEIAKu/WMn1b1Hv9 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hiroki Sato wrote: > va> > va> If a FreeBSD host receives router advertisements from several IPv6 > va> routers, on a LAN segment, which would be chosen as the default gatew= ay? >=20 > One reachable router will be selected based on the default router > preference value in RA, which is defined in RFC 4191. If all of the > routers have the same preference, the first one will win. >=20 > va> Can this be used for failover? >=20 > Yes. >=20 > Another way to realize failover is to use a common anycast address on > multiple routers. For example, a router is always able to have > fe80::/64 as an anycast address like this: >=20 > router# ifconfig igb0 inet6 fe80::/64 anycast >=20 > and you can simply configure fe80::/64 as the default router on the > hosts. Multiple routers with the same fe80::/64 can coexist on the > same segment, and hosts will choose one of them with no further > configuration. A caveat in this case is that the first router always > wins and there is no knob to set the preferences across the routers > with the same anycast address configured. Thank you Hiroki, this was very informative and useful. Can any IPv6 unicast or link-local address be configured as an anycast address of a router? Is this a replacement for VRRP and carp(4)?=20 --=20 Victor Sudakov, VAS4-RIPE, VAS47-RIPN 2:5005/49@fidonet http://vas.tomsk.ru/ --PEIAKu/WMn1b1Hv9 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEcBAEBAgAGBQJda9FnAAoJEA2k8lmbXsY0O0kIAKzE1B5osM27qk6vqPKBbTSI 2mHo4MG8MJzG+XTUNT7sr4kG1b1ABarkTA3iL2av93bEqNiQMAXbwVr3UVPptMIN eErkUENSQ66t2xa7eAVIW4/VA+hSJr7y35QKWgLlB7BnOXC4TgGTsK0QwwMcndqn xdGyLbQh4pE4LpQAkfX8juHTW2KWsEJsaxHQDDXaT/92MS2oEVfqmTn8W+ljnYqX GXM+2Xt4kZdLaYd6L0oM4LyT3KXoYbs74ZmXLcdKufCSMdgMiC2DHgCH2+GKobz+ TDYZUdxyd8IaTbar3N78rFBA0QhaH2KTVb5cDiMsMS0IEyBZmmvDFeu+xqlr5xo= =BYJc -----END PGP SIGNATURE----- --PEIAKu/WMn1b1Hv9--
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