> On Nov 20, 2021, at 20:37 , Joe Maimon <jmai...@jmaimon.com> wrote:
>
>
>
> Owen DeLong wrote:
>>
>>> On Nov 20, 2021, at 19:11 , Joe Maimon <jmai...@jmaimon.com> wrote:
>>>
>>>
>>>
>>> Owen DeLong wrote:
>>>> I guess I don’t see the need/benefit for a dedicated loopback prefix in
>>>> excess of one address. I’m not necessary inherently opposed to designating
>>>> one (which would be all that is required for IPv6 to have one, no software
>>>> updates would be necessary), but I’d need some additional convincing of
>>>> its utility to support such a notion.
>>> Since the loopback prefix in IPv4 is present and usable on all systems,
>>> IPv6 parity would require the same, so merely designating a prefix would
>>> only be the beginning.
>>>
>>> There may not be a need. But there is clearly some benefit.
>> Which is? You still haven’t answered that question.
>
> You have right below.
>
> And if there is indeed no benefit, than there is no reason not to repurpose
> 127/8 considering that you may use many other ranges in IPv4 for loopback and
> that you can just use IPv6 for loopback and there you go you have a whole /10.
One doesn’t need a reason for inaction… One needs a reason to act. There is (so
far) no compelling reason to repurpose 127/8 as far as I can see.
> Its not like it will overnight cause system admin headaches. And they should
> be running their loopback apps on IPv6 anyways.
You are arguing that just because we can do a thing, we should do a thing. I am
arguing that unless there’s a compelling reason to change the standard, we
should leave it as is until it dies a natural death of old age.
(or alternatively until we finally disconnect the life support keeping it
artificially alive which is a more accurate metaphor for the current state of
IPv4).
>> Well, technically, fe80::/10 is also present and predictable on every
>> loopback interface. It does come with the additional baggage of having to
>> specify a scope id when referencing it, but that’s pretty minor.
>>
>>
>> Nope… It’s every bit as deterministic as 127.0.0.0/8.
>>
>> If you send packets to fe80::*%lo0 on a linux box, they’ll get there. If you
>> try it on something other than linux, it probably doesn’t work.
>> That’s also true of 127.*.*.*.
>
> So fe80::/10 is the loopback prefix for IPv6
It’s link local. It’s present on loopback. fe80::/10%lo0 (on a linux box) is a
loopback prefix for IPv6 which is universally deployed.
The scope id becomes important in this context, but other than that, it’s
identical to the semantics of IPv4.
Owen