> > Is there really such as thing as pure IPV6 only? > Yup.
On Thu, Sep 8, 2022 at 11:32 AM Paul Amaral via NANOG <nanog@nanog.org> wrote: > Is there really such as thing as pure IPV6 only? I don’t think you will be > able to run IPV6 for transport without the router locally knowing how to > handle IPV4, at least not right now as there’s a lot of legacy code. > Usually IPV6 is enabled longer after IPV4 has been running. With that said, > can’t you just enable ipv4 and not route it passed the router, then use > RFC1918 to manually general your 32 bit ID. > > > > Paul > > > > *From:* NANOG <nanog-bounces+razor=meganet....@nanog.org> *On Behalf Of *Crist > Clark > *Sent:* Thursday, September 8, 2022 1:39 AM > *To:* nanog@nanog.org list <nanog@nanog.org> > *Subject:* Router ID on IPv6-Only > > > > During some IPv6 numbering discussions at work today, someone had a > question that I hadn't really considered before. How to choose 32-bit > router IDs for IPv6-only routers. > > > > Quick background. We have a requirement to convert a significant portion > of our network to IPv6-only over the next few years. Previously, I, and > everyone else on the team, have only ever set up routers in dual-stack > environments. Choosing a router ID for use in routing protocols just > followed whatever rules you used for your IPv4 networking. You used the > same router ID in IPv4 and IPv6. > > > > Well, now there is no IPv4. But BGP, OSPFv3, and other routing protocols > still use 32-bit router IDs for IPv6. On the one hand, there are plenty of > 32-bit numbers to use. Generally speaking, router IDs just need to be > unique inside of an AS to do their job, but (a) for humans or automation to > generate them and (b) to easily recognize them, it's convenient to have > some algorithm or methodology for assigning them. > > > > Has anyone thought about this or have a good way to do it? We had ideas > like use bits 32-63 from an interface. Seems like it could work, but also > could totally break down if we're using >64-bit prefixes for things like > router-to-router links or pulling router loopbacks out of a common /64. > > > > Also, various network OS implementations will typically automatically > choose a router ID from the IPv4 addresses on the router by some algorithm > (e.g. numerically lowest) if not explicitly configured. Was curious what > IPv6-only routers do. Haven't had the chance to get on some lab gear or > GNS3 to just try it and see. >
