Given the draft lies about the status of 127/8. Words have meanings. When all of 127.0.0.0/8 was reserved for loopback addressing, IPv4 addresses were not yet recognized as scarce. Today, there is no justification for allocating 1/256 of all IPv4 addresses for this purpose, when only one of these addresses is commonly used and only a handful are regularly used at all. Unreserving the majority of these addresses provides a large number of additional IPv4 host addresses for possible use, alleviating some of the pressure of IPv4 address exhaustion. It is not RESERVED, it is ASSIGNED. The class A network number 127 is assigned the "loopback" function, that is, a datagram sent by a higher level protocol to a network 127 address should loop back inside the host. No datagram "sent" to a network 127 address should ever appear on any network anywhere. If it was actually reserved there would be much less complaint. People have made use of that space based on the fact that it was ASSIGNED a purpose whether you like that or feel that it was a good use of resources. Compulsory acquisition is something that should not be done lightly. It also requires fair compensation to be paid.
On 9 Mar 2022, at 13:35, Seth David Schoen <schoen@loyalty.org> wrote:
John R. Levine writes:
This still doesn't mean that screwing around with 240/4 or, an even worse 127/8 minus 127/24, is a good idea.
I hope you'll be slightly mollified to learn that it's actually 127/8 minus 127/16.
https://datatracker.ietf.org/doc/draft-schoen-intarea-unicast-127/
That's the most challenging one, but we've still seen something of a lack of people getting in touch to point out concrete problems.
One person did get in touch to describe an unofficial use of, apparently, all of 127/8 as private address space in a VPN product. If people let us know about more, we can investigate workarounds or possible changes to our proposals.
What’s “unofficial” about it? The point of ASSIGNING 127/8 for loopback meant the ANYONE could use that address space OFFICIALLY so long as packets with those addresses didn’t leave the machine.
We previously thought that the reference NTP implementation was using all of 127/8 to identify hardware clock drivers. But it turns out it doesn't actually connect to these.
If anyone reading this knows of something that uses a loopback address outside of 127/16 for an application, or something that can't be updated and would be harmed if the rest of the network stopped treating this as loopback, we'd be glad to hear about it.
What does it matter what people are using those addresses for. They are using them in good faith and are under no obligation to report how they are using them. -- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: marka@isc.org