Date: Thu, 12 Sep 2019 11:14:12 +0700 From: Victor Sudakov <vas@mpeks.tomsk.su> To: freebsd-net@freebsd.org Subject: Re: Several IPv6 routers and default gateway choice Message-ID: <20190912041412.GA2851@admin.sibptus.ru> In-Reply-To: <20190912.123249.93293774363511628.hrs@allbsd.org> References: <20190901141047.GA56954@admin.sibptus.ru> <20190902.044135.1812305046881448068.hrs@allbsd.org> <20190906035608.GA45741@admin.sibptus.ru> <20190912.123249.93293774363511628.hrs@allbsd.org>
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--UugvWAfsgieZRqgk Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable 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 anyca= st > 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. >=20 > They will be automatically configured when an ipv6_prefix_IF > rc.conf(5) variable is used to configure a prefix: >=20 > ----(from rc.conf(5) man page)---- > ipv6_prefix_ed0=3D"2001:db8:1:0 2001:db8:2:0" >=20 > is equivalent to the following: >=20 > ifconfig_ed0_alias0=3D"inet6 2001:db8:1:: eui64 prefixlen 64" > ifconfig_ed0_alias1=3D"inet6 2001:db8:1:: prefixlen 64 anycast" > ifconfig_ed0_alias2=3D"inet6 2001:db8:2:: eui64 prefixlen 64" > ifconfig_ed0_alias3=3D"inet6 2001:db8:2:: prefixlen 64 anycast" >=20 > These Subnet-Router anycast addresses will be added only when > ipv6_gateway_enable is YES. > ---------------------------------- Dear Hiroki, You are an invaluable source of information. I wish all the above should make it into the Handbook, the chapter on IPv6. --=20 Victor Sudakov, VAS4-RIPE, VAS47-RIPN 2:5005/49@fidonet http://vas.tomsk.ru/ --UugvWAfsgieZRqgk Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEcBAEBAgAGBQJdecYUAAoJEA2k8lmbXsY0rV8H+wcqmOBz9RD/Rfg7xPSH4Hat B5uZoHEkCnRS9XzCechvjFI0X76BmT7Rhkqlkkp0xUr6avVJl6dwvEnEfPFCCQze ZS+gMLGgEwWYK0Og5irsle9Clp4kajqtuaUT6v2EksxLjn55eaHk78EU6NXwixv5 IaezhI4fA/p0nMEPSqHog+6usVCODQe+QJ/xxvSjmsGNOLipr6hwyWRVl+o2MuIK 5mI/EIIxV/p3wP7DzBlR8jqahw8e3Q/svuq2HTdM+zJKt9WqpMBMwWh6mS5Wbv8P ubFT6fzLy50ip66CB7jfUmlavQ3q0JPEzKrZ/sK95oXEgiVoW2wjjGKRS1jy2X8= =3UiN -----END PGP SIGNATURE----- --UugvWAfsgieZRqgk--
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