From owner-freebsd-net@freebsd.org Fri Aug 30 03:16:58 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 EF68DE7B2E for ; Fri, 30 Aug 2019 03:16:58 +0000 (UTC) (envelope-from hrs@allbsd.org) Received: from mail.allbsd.org (mx.allbsd.org [IPv6:2001:2f0:104:e001::41]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) server-signature RSA-PSS (4096 bits) client-signature ECDSA (P-384) client-digest SHA384) (Client CN "mail.allbsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 46KPlr1LqFz4ZGd for ; Fri, 30 Aug 2019 03:16:55 +0000 (UTC) (envelope-from hrs@allbsd.org) Received: from mail-d.allbsd.org ([IPv6:2409:11:a740:4700:58:65ff:fe00:b0b]) (authenticated bits=56) by mail.allbsd.org (8.15.2/8.15.2) with ESMTPSA id x7U3GAEx068852 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=OK) (Client CN "/CN=mail-d.allbsd.org", Issuer "/C=US/O=Let's+20Encrypt/CN=Let's+20Encrypt+20Authority+20X3"); Fri, 30 Aug 2019 12:16:28 +0900 (JST) (envelope-from hrs@allbsd.org) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=allbsd.org; s=20190220; t=1567134999; bh=Xnw+T+T6jsAnkXtQeaitynaY2FDPDv/CZB9RGdcau44=; h=Date:To:Cc:From:In-Reply-To:References; b=sNWhVb/ilaeIR31puj+LeduEuLR6hlNP/oGJ/u0NOWW3bgdPRfuAo5hVJqBCaBOS+ ISsrRxcmDqK9SWA7gAZzwrQpa5+8f7h0fW3za59EiQedYazcc0UDafZRKAJQDBRpB9 opq2BQq5jQPbdx3Pbjex3aa6UoOWtg6ePtsiAQzA= Received: from alph.d.allbsd.org ([IPv6:2409:11:a740:4700:16:ceff:fe34:2700]) by mail-d.allbsd.org (8.15.2/8.15.2) with ESMTPS id x7U3G405010826 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Fri, 30 Aug 2019 12:16:04 +0900 (JST) (envelope-from hrs@allbsd.org) Received: from localhost (localhost [[UNIX: localhost]]) (authenticated bits=0) by alph.d.allbsd.org (8.15.2/8.15.2) with ESMTPA id x7U3G0eZ010822; Fri, 30 Aug 2019 12:16:04 +0900 (JST) (envelope-from hrs@allbsd.org) Date: Fri, 30 Aug 2019 12:15:43 +0900 (JST) Message-Id: <20190830.121543.1108900942284640156.hrs@allbsd.org> To: vas@mpeks.tomsk.su Cc: freebsd-net@freebsd.org Subject: Re: Several IPv6 routers and default gateway choice From: Hiroki Sato In-Reply-To: <20190830021228.GA66465@admin.sibptus.ru> References: <20190830021228.GA66465@admin.sibptus.ru> X-Old-PGPkey-fingerprint: BDB3 443F A5DD B3D0 A530 FFD7 4F2C D3D8 2793 CF2D X-PGPkey-fingerprint: 6C0D 2353 27CF 80C7 901E FDD2 DBB0 7DC6 6F1F 737F X-Mailer: Mew version 6.8 on Emacs 26.2 Mime-Version: 1.0 Content-Type: Multipart/Signed; protocol="application/pgp-signature"; micalg=pgp-sha512; boundary="--Security_Multipart(Fri_Aug_30_12_15_43_2019_253)--" Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.6.2 (mail.allbsd.org [IPv6:2001:2f0:104:e001:0:0:0:41]); Fri, 30 Aug 2019 12:16:39 +0900 (JST) X-Rspamd-Queue-Id: 46KPlr1LqFz4ZGd X-Spamd-Bar: ------ Authentication-Results: mx1.freebsd.org; dkim=pass header.d=allbsd.org header.s=20190220 header.b=sNWhVb/i; dmarc=none; spf=pass (mx1.freebsd.org: domain of hrs@allbsd.org designates 2001:2f0:104:e001::41 as permitted sender) smtp.mailfrom=hrs@allbsd.org X-Spamd-Result: default: False [-6.24 / 15.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; R_DKIM_ALLOW(-0.20)[allbsd.org:s=20190220]; NEURAL_HAM_MEDIUM(-1.00)[-1.000,0]; FROM_HAS_DN(0.00)[]; R_SPF_ALLOW(-0.20)[+mx]; MV_CASE(0.50)[]; MIME_GOOD(-0.20)[multipart/signed,text/plain]; TO_DN_NONE(0.00)[]; DMARC_NA(0.00)[allbsd.org]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; RCVD_COUNT_THREE(0.00)[4]; TO_MATCH_ENVRCPT_SOME(0.00)[]; DKIM_TRACE(0.00)[allbsd.org:+]; RCPT_COUNT_TWO(0.00)[2]; MID_CONTAINS_FROM(1.00)[]; NEURAL_HAM_SHORT(-0.99)[-0.989,0]; 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:7514, ipnet:2001:2f0::/32, country:JP]; IP_SCORE(-2.15)[ip: (-9.76), ipnet: 2001:2f0::/32(-4.31), asn: 7514(3.33), country: JP(-0.03)] 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: Fri, 30 Aug 2019 03:16:59 -0000 ----Security_Multipart(Fri_Aug_30_12_15_43_2019_253)-- Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Victor Sudakov wrote in <20190830021228.GA66465@admin.sibptus.ru>: va> Dear Colleagues, 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 gateway? 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. va> Can this be used for failover? Yes. 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: router# ifconfig igb0 inet6 fe80::/64 anycast 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. -- Hiroki ----Security_Multipart(Fri_Aug_30_12_15_43_2019_253)-- Content-Type: application/pgp-signature Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- iMgEABMKAC0WIQRsDSNTJ8+Ax5Ae/dLbsH3Gbx9zfwUCXWiU3w8caHJzQGFsbGJz ZC5vcmcACgkQ27B9xm8fc3/TcAIIpMfBK171VP5Wr0/6zkFZo3liHRZWReklB/dY 5Ot4kIBkzuogJLAImvikDG2M7RAPQ2O9tu26iq5/+8dSWM7WsSsCCQHQUtZvtqKp XuRAfgfyru94ji3gdN0liAWdpkBxEMPlUgUsTlSVnA9s+JUKitChfAICvnEAbd6N WYsQrM4fLdEHbg== =qcBz -----END PGP SIGNATURE----- ----Security_Multipart(Fri_Aug_30_12_15_43_2019_253)----