You can’t use multicast because multicast addresses work today on private networks

Lol, then what do we do with all the multicast traffic?

Surely something from https://en.wikipedia.org/wiki/Reserved_IP_addresses could be repurposed?

Why? It would be to the benefit of relatively few and be an enormous technical problem for everyone for decades. If we did this, the IPv4 addresses would run out again after a few months at most, leaving us all in the same position we are in today, but also with a huge technical problem of fixing all the old devices which had these now-repurposed networks hardcoded.

If you are fine with doing the work of obsoleting old equipment, then just start using IPv6.

240/4 can be hijacked/used as private IP space currently by a lot of devices. I think Windows might be the hold out. But for internal routing and IoT it’s very useful. Can never be used as publicly routable space.

I’d like to see it added to the official list of private space alongside RFC1918.

Not sure why you'd need more than 10/8, but I suppose it looks even cooler too those who know and find such things cool.

Does Windoze prevent you from using certain IPv4 addresses?

Aws sized companies, we also use them in aws. And no doesn't work on windows.

> Not sure why you'd need more than 10/8

Large organizations have moved to IPv6 because they, and everyone else, are using 10/8, and so when mergers and acquisitions happen trying to connect the networks together becomes a nightmare.

See this talk from Wells Fargo as an example:

* https://www.youtube.com/watch?v=EzTWjNUb4H4

The pain of merging acquired company networks cannot be overstated!

IPv6 can help, but in my experience there's just soo much old IPv4 tech that no one is prepared to migrate to IPv6.

https://www.ietf.org/archive/id/draft-schoen-intarea-unicast... is a nice historical overview of 240/4

Holy cow. Didn’t realize there is an entire /4 reserved for future use.

No. It will take 10 years for everyone to update their router configuration/software to treat the new “formely-reserved” addresses as global unicast. There’s no point in doing that whatsoever. That effort would be spent much better by adopting IPv6.

and what, earn 5 more years till we have the same problem?

That's a problem for the people in 5 years

At this point, time would be better spent moving to IPv6, don't you think?

We have been trying to deploy IPv6 for 20 years now. This would be comparatively easier and buy us another 20 years to finish v6 deployment.

A ton of old equipment would need to be upgraded to use 240/4 for IPv4 unicast. We'd run into weird issues where it works for some people and not others. I'm not convinced. If this was done 25 years ago, maybe.

And 50% of the internet traffic is IPv6. The proposal here is to introduce a separate (arguably harder) change which would start at 0% support again. Beyond that, it'd just be a temporary fix.

Just 240/4 allowed specifically for private network use (like the 10/8 range)... that I could get behind though. This would still exclude 255.255.255.255/32 of course.

The problem is that you can't really move completely to IPv6. You actually will have to run both IPv4 and IPv6 networks indefinitely. Which isn't a lot of fun.

Now, yes. But eventually, we'll reach a tipping point where that isn't necessary. When? Your guess is as good as mine.

"You actually will have to run both IPv4 and IPv6 networks *indefinitely*."

Sure you can. You can do it today even, let alone in some unspecified number of years.