Re: Redploying most of 127/8 as unicast public

[Owen DeLong via NANOG <nanog () nanog org>]

This will break a significant number of existing deployments where people
have come to depend on a feature in Linux where any address within 127.0.0.0/8
can be “listened” and operate as a valid loopback address without configuring
the addresses individually as unicast on the interface.

In fact, this is true of any prefix assigned to the loopback interface, but 127.0.0.0/8
is automatic and difficult to change.

While I’m not sure this implementation in the Linux kernel was such a wonderful
idea, it is widely deployed and in use in a number of environments.

If we’re still using IPv4 widely enough that GUA space matters, we will have
far bigger problems than the lack of available GUA for it.

Owen


> On Nov 17, 2021, at 16:15 , William Herrin <bill () herrin us> wrote:
>
> On Wed, Nov 17, 2021 at 3:31 PM Jay R. Ashworth <jra () baylink com> wrote:
> > This seems like a really bad idea to me; am I really the only one who noticed?
> >
> > https://www.ietf.org/id/draft-schoen-intarea-unicast-127-00.html
>
> Hi Jay,
>
> I think it's a good idea. It won't be usable any time in the next two
> decades but if we're still using IPv4 in two decades we'll be glad to
> have anything we can scrounge. Why not ask OS authors to start
> assigning 127.0.0.1/16 to loopback instead of 127.0.0.1/8?
>
> Regards,
> Bill Herrin
>
>
> -- 
> William Herrin
> bill () herrin us
> https://bill.herrin.us/