Hi Remco, I also like this idea. In addition to Jen’s comments.
I’m a little skeptical about magic. I.e. using the special IPv4 address both to signal that IPv6 router discovery should be used and to represent the IPv6 next-hop(s). I’m also skeptical about how the “rest” of the routing stack is meant to deal with this. e.g. a manually added static route like “ip route add 0.0.0.0/0 via 192.0.0.11”. I haven’t tried to implement this so I am sure there are more gremlins that I haven’t thought of. Could we somehow make this explicitly signalled? So the default route would look like: “0.0.0.0/0 via fe80::1” Compatible with draft-ietf-intarea-v4-via-v6. Regardless of approach this would also break the assumption that the default gateway is on-link. It would be neat to have text explicitly stating that (and have implementations support it if NH is v4 instead of depending on DHCP static route option trickery). Best regards, Ole > On 21 Oct 2025, at 13:06, Remco van Mook <[email protected]> wrote: > > Dear all, > > I'd like to draw your attention to a draft I submitted last night - > https://datatracker.ietf.org/doc/draft-ipv6-resolved-gateway/ . > The short version is to get a standardised approach for hosts to send IPv4 > traffic to the link layer address of their IPv6 default gateway, bypassing > the need for v4 subnetting and link layer discovery (ARP) to send IPv4 > traffic upstream. > This aligns fully with the current v4-via-v6 efforts that are currently > ongoing inside of the IETF, and extends it to the host level. The approach is > to assign an address from the IPv4 special purpose registry to this end - i.e > if this IP address is found as default gateway, the host should use IPv6 > NDP/RA to resolve the link layer next hop. This can be made fully backward > compatible by having the gateway also send ARP replies for this IP if needed. > > I presented on this during RIPE91, currently in Bucharest. Due to > overwhelmingly positive response (and a midnight deadline that I was unaware > of until then) to just submit the I-D in its current rough form. > > The presentation can be found here: > https://ripe91.ripe.net/programme/meeting-plan/sessions/10/Y8YVLE/ > I would very much like to hear your opinion - I've asked the chair for an > opportunity to present on this at the Montreal meeting. > > Kind regards > > Remco van Mook > _______________________________________________ > Int-area mailing list -- [email protected] > To unsubscribe send an email to [email protected] _______________________________________________ Int-area mailing list -- [email protected] To unsubscribe send an email to [email protected]
