On Sun, Aug 01, 2021 at 10:59:16PM -0700, Seth David Schoen wrote: > Hi, > > John Gilmore, Dave Taht and I have proposed a recent Internet-Draft that > relates to the Internet Area. We hope you'll read it and discuss it: > > https://datatracker.ietf.org/doc/draft-schoen-intarea-lowest-address/
I'd suggest you'd have a hard job making local links safe for on-link use of the all-0-host address, if only because of the number of routers deployed (e.g. Cisco boxes, but probably others as wlll) which have that knowledge hard coded. i.e. they treat them on RX just like the IPv6 "any router" case, so will not ARP for the target. It isn't difficult to remove from some places in s/w, but getting the boxes upgraded may well be difficult. Fixing the 'directed broadcast' case was an easier sell. So I'd suggest that ship has sailed wrt on-link all-0-host addresses. That said, I already make use of the the subnet all-0 and all-1 host addresses, but off-link. e.g. as NAT addresses because off link devices simply can not know where the CIDR boundaries are. I suspect that is about the best which can be done. I'd suggest it wouldn't be safe to hand such out to "normal" hosts, e.g. by DHCP, but one could envisage some special UDP based services using the address. So while we could make this change, I suspect it will be a long time before such all-0-host addresses are generally usable on-link. It is possible some routers drop off-link packets destined to the all zero host address not only due to ACLs, but due to the don't forward directed broadcast behaviour. (Note you could also pursue deprecating the all-1-host address being used as a local broadcast, as 255.255.255.255 can replace most such on link uses. That would also strike me as a forlone hope). DF _______________________________________________ Int-area mailing list [email protected] https://www.ietf.org/mailman/listinfo/int-area
