From owner-freebsd-net@freebsd.org Sun Sep 1 14:10:57 2019 Return-Path: Delivered-To: freebsd-net@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 9BD26DB316 for ; Sun, 1 Sep 2019 14:10:57 +0000 (UTC) (envelope-from vas@mpeks.tomsk.su) Received: from admin.sibptus.ru (admin.sibptus.ru [IPv6:2001:19f0:5001:21dc::10]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 46Lw9X38hCz4M9s for ; Sun, 1 Sep 2019 14:10:55 +0000 (UTC) (envelope-from vas@mpeks.tomsk.su) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sibptus.ru; s=20181118; h=In-Reply-To:Message-ID:Subject:To:From:Date; bh=2zeJp7L7Kf9LUzKXNuCeGxDY9SU0ZAegy90oS7rKkAg=; b=Q8bA4WmtGT5wnFn2RmbBzC1YFB lNvZgB696QRn81NFCSfibKjJjeFWAkCVmPKtO+J2jJY0l5QQh0b/rOYi1+QzCPBFYwI3hKRdnjH96 8JfG6hneD3lzFJPIf/kkaRnGz+2DzJvojpu+GVfnQ1ECahT/reyDMV/Ox9gO00eX55l8=; Received: from vas by admin.sibptus.ru with local (Exim 4.92.1 (FreeBSD)) (envelope-from ) id 1i4QZ5-000Eqf-Tl for freebsd-net@freebsd.org; Sun, 01 Sep 2019 21:10:47 +0700 Date: Sun, 1 Sep 2019 21:10:47 +0700 From: Victor Sudakov To: freebsd-net@freebsd.org Subject: Re: Several IPv6 routers and default gateway choice Message-ID: <20190901141047.GA56954@admin.sibptus.ru> References: <20190830021228.GA66465@admin.sibptus.ru> <20190830.121543.1108900942284640156.hrs@allbsd.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="PEIAKu/WMn1b1Hv9" Content-Disposition: inline In-Reply-To: <20190830.121543.1108900942284640156.hrs@allbsd.org> X-PGP-Key: http://admin.sibptus.ru/~vas/ X-PGP-Fingerprint: 10E3 1171 1273 E007 C2E9 3532 0DA4 F259 9B5E C634 User-Agent: Mutt/1.12.1 (2019-06-15) Sender: Victor Sudakov X-Rspamd-Queue-Id: 46Lw9X38hCz4M9s X-Spamd-Bar: -------- Authentication-Results: mx1.freebsd.org; dkim=pass header.d=sibptus.ru header.s=20181118 header.b=Q8bA4Wmt; dmarc=none; spf=pass (mx1.freebsd.org: domain of vas@mpeks.tomsk.su designates 2001:19f0:5001:21dc::10 as permitted sender) smtp.mailfrom=vas@mpeks.tomsk.su X-Spamd-Result: default: False [-8.57 / 15.00]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-1.000,0]; R_DKIM_ALLOW(-0.20)[sibptus.ru:s=20181118]; FROM_HAS_DN(0.00)[]; R_SPF_ALLOW(-0.20)[+mx]; TO_MATCH_ENVRCPT_ALL(0.00)[]; MIME_GOOD(-0.20)[multipart/signed,text/plain]; TO_DN_NONE(0.00)[]; DMARC_NA(0.00)[tomsk.su]; RCPT_COUNT_ONE(0.00)[1]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; IP_SCORE(-2.98)[ip: (-9.46), ipnet: 2001:19f0:5000::/38(-4.73), asn: 20473(-0.65), country: US(-0.05)]; DKIM_TRACE(0.00)[sibptus.ru:+]; NEURAL_HAM_SHORT(-0.99)[-0.991,0]; SIGNED_PGP(-2.00)[]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+,1:+,2:~]; RCVD_TLS_LAST(0.00)[]; ASN(0.00)[asn:20473, ipnet:2001:19f0:5000::/38, country:US]; RCVD_COUNT_TWO(0.00)[2] X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 01 Sep 2019 14:10:57 -0000 --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--