Redploying most of 127/8 as unicast public

Fri Nov 19 17:56:00 UTC 2021

So see, that was kinda my view, though I hadn't realized there was a kernel
hack advancing the football...

----- Original Message -----
> From: "Owen DeLong" <owen at delong.com>
> To: "William Herrin" <bill at herrin.us>
> Cc: "jra" <jra at baylink.com>, "nanog" <nanog at nanog.org>
> Sent: Friday, November 19, 2021 9:28:01 AM
> Subject: Re: Redploying most of 127/8 as unicast public

> 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 at herrin.us> wrote:
>> 
>> On Wed, Nov 17, 2021 at 3:31 PM Jay R. Ashworth <jra at 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 at herrin.us
> > https://bill.herrin.us/

-- 
Jay R. Ashworth                  Baylink                       jra at baylink.com
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