Date: Fri, 6 Sep 2019 19:06:36 -0700 From: Kevin Oberman <rkoberman@gmail.com> To: Victor Sudakov <vas@mpeks.tomsk.su> Cc: freebsd-net <freebsd-net@freebsd.org> Subject: Re: Several IPv6 routers and default gateway choice Message-ID: <CAN6yY1sNif16MNgH5Pd5AXBEtwVG5PF=Mkh9FNYr2MwvcigH3A@mail.gmail.com> In-Reply-To: <20190906035608.GA45741@admin.sibptus.ru> References: <20190830021228.GA66465@admin.sibptus.ru> <20190830.121543.1108900942284640156.hrs@allbsd.org> <20190901141047.GA56954@admin.sibptus.ru> <20190902.044135.1812305046881448068.hrs@allbsd.org> <20190906035608.GA45741@admin.sibptus.ru>
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On Thu, Sep 5, 2019 at 8:56 PM Victor Sudakov <vas@mpeks.tomsk.su> wrote: > Hiroki Sato wrote: > > va> Can any IPv6 unicast or link-local address be configured as an > anycast > > va> address of a router? > > > > Yes. There is no restriction about address scope. > > > > You might want to read RFC 4291, which defines Subnet-Router anycast > > address, and RFC 2526, which defines the other reserved IPv6 subnet > > anycast addresses. In general, the former one can be used for > > routing purpose. > > Interestingly, RFC4291 says that "All routers are required to support > the Subnet-Router anycast addresses for the subnets to which they have > interfaces." In practice, I don't observe this. A FreeBSD router does > not configure such an address automatically, for example. > > RFC2526 is dim, I think it's because of this RFC the last usable address > on a subnet ends in ff7f instead of ffff. I wonder if anyone anywhere > uses those subnet anycast addresses. > I have to look it up on the status page, but I thought 2526 had been deprecated back before I retired. I thought I discovered this while setting up anycast for our DNS servers. I'll look when I get back from walking our dog. (Priorities change when you retire.)
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