On Tue, Feb 13, 2024 at 2:34 PM Christopher Hawker <chris@thesysadmin.au> wrote:
Having [240/4] reclassified as unicast space is indeed much easier.
Hi Chris, If I were spending my time on the effort, that's what I'd pursue. It's a low-impact change with no reasonable counter-argument I've seen. As you noted, half the vendors already treat it as unicast space anyway.
With that, comes the argument - what about legacy hardware that vendors no longer support, or are out of warranty and no longer receive software updates?
What about legacy hardware that doesn't support CIDR? What about the 1990s Sparc Stations that don't have enough ram to run anything vaguely like a modern web browser? You make the key standards change (from reserved undefined use to reserved unicast use) and over time varying potential uses for those unicast addresses become practical despite the receding legacy equipment. None of us has a crystal ball saying when IPv4 use will start to fall off. It's entirely possible It'll still be going strong in 20 more years. If so, and if 240/4 was defined as unicast now, it'll surely be practical to use it by then. Making the simple standards change also lets us debate the "best" use of the addresses while the needed software change happens in parallel, instead of holding up the software changes while we debate. Allocating them to the RIRs isn't the only practical use of a new set of unicast IP addresses. Other plausible uses include: * More RFC1918 for large organizations. * IXP addresses which only host routers, not the myriad servers and end-user client software. * ICMP unreachable source address block, for use by routers which need to emit a destination unreachable message but do not have a global IP address with which to do so. * A block of designated private-interconnect addresses intended to be used by off-internet networks using overlapping RFC1918 which nevertheless need to interconnect. Indeed, the only use for which we definitely -don't- need more IPv4 addresses is Multicast. So, a rush to deploy 240/4 to RIRs is not really warranted. Regards, Bill Herrin -- William Herrin bill@herrin.us https://bill.herrin.us/