On Sat 13 Aug 2022 at 09:37:02 (-0000), Curt wrote: > On 2022-08-13, David Wright <deb...@lionunicorn.co.uk> wrote: > > On Wed 10 Aug 2022 at 08:12:11 (-0000), Curt wrote: > >> I never realized that local addresses were fundamentally identical in all > >> local networks because there weren't enough addresses in the first place, > > > > Don't you need them to be identical because otherwise everybody > > would have to configure their border equipment (like routers) > > to recognise /their/ choice as local. > > I guess they've got it all figured out. > > > It's not clear, either, how you would select your own local > > range without accidentally choosing addresses that are in use > > somewhere on the globe, unless the choice was a fixed, well- > > known set of possible values (as it is: 10, 172.16–31, 192.168). > > The IETF RFC 7084 (formerly RFC 6204), Basic Requirements for IPv6 > Customer Edge Routers, [ … … … … ]
AFAICT the rest of your post is concerned with global IPv6 addresses rather than local (ULA) ones, which is why the prefix for the home LAN has to be given to you rather than generated/assigned by yourself. AIUI IPv6 local addresses are designed to be not fundamentally identical, by having a 40-bit pseudorandom global ID embedded within them. So were they to leak out onto the Internet, the chances are that you wouldn't get a collision. (Mind you, I don't know just what that chance would be.) OTOH the betting is that the IPv4 address of a home internet's router, for example, is going to be either 192.168.1.1 or 192.168.0.1, with a scattering of 192.168.1.254 (like British Telecom users, YMMV). And not forgetting Gene's choice of 71. Cheers, David.
