From owner-freebsd-net@freebsd.org Thu Sep 12 03:33:45 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 D58ACE8BFD for ; Thu, 12 Sep 2019 03:33:45 +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 46TPWB2CSNz3FqW for ; Thu, 12 Sep 2019 03:33:41 +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 x8C3X99D050498 (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"); Thu, 12 Sep 2019 12:33:22 +0900 (JST) (envelope-from hrs@allbsd.org) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=allbsd.org; s=20190220; t=1568259210; bh=9s6MJJq9JewJhPvxZCBuPK0u4+Ojp2dYb0emVuzRwxM=; h=Date:To:Cc:From:In-Reply-To:References; b=nQoYKYWoAY+Tfyb02XAV+M74eVEtWRBpAELdNlJRHefXuvucvzIFU/fmVq7GSALDC takj+ZqX1LxdPqizs+uLnWFvAnl3B8kDrUHCxYUeoVCrXu6mycx+8FAGiABll6QNCe tFa/sxp6zr8yiv67AmlJ4D/lLZhuP/6nYq0D7Nkc= 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 x8C3X3x3020233 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Thu, 12 Sep 2019 12:33:04 +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 x8C3X0ob020225; Thu, 12 Sep 2019 12:33:03 +0900 (JST) (envelope-from hrs@allbsd.org) Date: Thu, 12 Sep 2019 12:32:49 +0900 (JST) Message-Id: <20190912.123249.93293774363511628.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: <20190906035608.GA45741@admin.sibptus.ru> References: <20190901141047.GA56954@admin.sibptus.ru> <20190902.044135.1812305046881448068.hrs@allbsd.org> <20190906035608.GA45741@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(Thu_Sep_12_12_32_49_2019_424)--" 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]); Thu, 12 Sep 2019 12:33:30 +0900 (JST) X-Rspamd-Queue-Id: 46TPWB2CSNz3FqW X-Spamd-Bar: ----- Authentication-Results: mx1.freebsd.org; dkim=pass header.d=allbsd.org header.s=20190220 header.b=nQoYKYWo; 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 [-5.01 / 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)[]; 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(-1.91)[ip: (-8.56), ipnet: 2001:2f0::/32(-3.84), asn: 7514(2.86), country: JP(-0.02)] 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: Thu, 12 Sep 2019 03:33:45 -0000 ----Security_Multipart(Thu_Sep_12_12_32_49_2019_424)-- Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Victor Sudakov wrote in <20190906035608.GA45741@admin.sibptus.ru>: va> Hiroki Sato wrote: va> > va> Can any IPv6 unicast or link-local address be configured as an anycast va> > va> address of a router? va> > va> > Yes. There is no restriction about address scope. va> > va> > You might want to read RFC 4291, which defines Subnet-Router anycast va> > address, and RFC 2526, which defines the other reserved IPv6 subnet va> > anycast addresses. In general, the former one can be used for va> > routing purpose. va> va> Interestingly, RFC4291 says that "All routers are required to support va> the Subnet-Router anycast addresses for the subnets to which they have va> interfaces." In practice, I don't observe this. A FreeBSD router does va> not configure such an address automatically, for example. They will be automatically configured when an ipv6_prefix_IF rc.conf(5) variable is used to configure a prefix: ----(from rc.conf(5) man page)---- ipv6_prefix_ed0="2001:db8:1:0 2001:db8:2:0" is equivalent to the following: ifconfig_ed0_alias0="inet6 2001:db8:1:: eui64 prefixlen 64" ifconfig_ed0_alias1="inet6 2001:db8:1:: prefixlen 64 anycast" ifconfig_ed0_alias2="inet6 2001:db8:2:: eui64 prefixlen 64" ifconfig_ed0_alias3="inet6 2001:db8:2:: prefixlen 64 anycast" These Subnet-Router anycast addresses will be added only when ipv6_gateway_enable is YES. ---------------------------------- va> RFC2526 is dim, I think it's because of this RFC the last usable address va> on a subnet ends in ff7f instead of ffff. I wonder if anyone anywhere va> uses those subnet anycast addresses. That is because there are few practical applications of the IPv6 anycast address other than failover across multiple routers. -- Hiroki ----Security_Multipart(Thu_Sep_12_12_32_49_2019_424)-- Content-Type: application/pgp-signature Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- iMgEABMKAC0WIQRsDSNTJ8+Ax5Ae/dLbsH3Gbx9zfwUCXXm8YQ8caHJzQGFsbGJz ZC5vcmcACgkQ27B9xm8fc38S/gIJAcwUb3Ryw6kARieLYhNOMv5BH0VsyVVuXNHu xqnZvUX2OuzHOdXEWPSKSifKarzg/dzbaQJQfvb6Tv6tfnF+382TAgiChka4ljSk BAWxqFtRSOQCTLi1MaJ/5U5XNnTAH/+uRLpZfcXofojot20SCkOeIF4tFGxJ+hb9 Aafc4L7UMWBOcw== =9znI -----END PGP SIGNATURE----- ----Security_Multipart(Thu_Sep_12_12_32_49_2019_424)----