Re: Non routable IPv6 registry proposal

[David Farmer <[e-mail]>]

Fred,

Yes, I agree with what you are saying, but I’m confused, what does that
have to do with ULA?

On Thu, Mar 11, 2021 at 16:25 Fred Baker <[e-mail]> wrote:

> I can tell you definitively that the DNS Root Servers use IPv6 addresses
> for anycast, but they are indistinguishable from unicast addresses in
> format. The anycast magic is in BGP.
>
> Sent using a machine that autocorrects in interesting ways...
>
> On Mar 11, 2021, at 12:53 PM, David Farmer <farmer=
> [e-mail]> wrote:
>
> 
>
> On Thu, Mar 11, 2021 at 2:16 PM Brian E Carpenter <
> [e-mail]> wrote:
>
>> David,
>> On 12-Mar-21 08:19, David Farmer wrote:
>> > On Thu, Mar 11, 2021 at 10:49 AM Keith Moore <
>> [e-mail] <mailto:[e-mail]>> wrote:
>> >
>> >     On 3/11/21 5:22 AM, Nico Schottelius wrote:
>> >
>> >>>     Another question I have is whether such ULA allocations
>> >>>     will realistically remain local.
>> >>     ULAs are unlikely staying local, as we have seen with radio
>> networks in
>> >>     Germany. Tunnels are being used to interconnect remote cities and
>> >>     non-collision (not necessarily public routing) are a primary
>> concern.
>> >
>> >     Despite the name, there's no reason that ULAs should stay local.
>> As long as they are properly chosen, it's perfectly reasonable to route
>> them privately between cooperating networks, and IMO this is part of their
>> design.   One of the problems with RFC 1918 addresses in IPv4 was that
>> enterprises had a need to route traffic between networks each using that
>> space.   The resulting address collisions generally required explicit NAT
>> configurations to work around, and these were failure-prone and difficult
>> to manage.  ULAs were intended in part to remedy this problem.
>> >
>> >     Keith
>> >
>> > The "L" for Local isn't intended to have a strict definition of Local.
>> However, similarly, the "U" for Unique isn't intended to have a strict
>> definition of Unique either, especially a mathematical definition of
>> Unique.
>> >
>> > You can easily interconnect thousands or even tens of thousands of ULA
>> prefixes without much chance of an address collision, as long as the random
>> assignment process is actually used. Whereas, if you try to interconnect
>> billions of ULA prefixes, you will probably start running into the birthday
>> paradox.
>> >
>> > So the interconnection of ULA prefixes, the route-ability of them, is
>> not intended to be unlimited. There are limits to the number of ULA
>> prefixes that SHOULD be interconnected to each other; nevertheless, this
>> limit is extremely generous for the intended use cases.
>> >
>> > If you disregard the intended use cases and use them outside the
>> intended use cases, then address collisions could become an issue.
>>
>> I'm not sure where you get your "intended" from. I don't think we've ever
>> really written done the intended use cases in such detail. (Except for the
>> abandoned
>> https://datatracker.ietf.org/doc/html/draft-ietf-v6ops-ula-usage-considerations-02
>> )
>>
>>     Brian
>>
>
> The first sentence of the Abstract for RFC4193 says;
>
>
> This document defines an IPv6 unicast address format that is globally
> unique and is intended for local communications, usually inside of a site.
>
>
> This is expanded upon in the first paragraph of the Introduction to
> RFC4193;
>
> This document defines an IPv6 unicast address format that is
> globally unique and is intended for local communications [IPV6]. ...
> They are routable inside of a more limited area such as a site.  They may
> also be routed between a limited set of sites.
>
>
> Those sound a lot like intended use cases to me, the key phrases in that
> for me are, "local communications", "usually ... a site", and "a limited
> set of sites."
>
> Yes, that's pretty vague, but I don't see a reasonable interpretation of
> those phrases that include every site on the Internet, or even every site
> in a country or state, maybe it could include every site in a small to
> modest city, but even that's a bit of a stretch in my opinion.
>
> YMMV
> Thanks
>
>
> --
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> David Farmer               Email:[e-mail]
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> --
===============================================
David Farmer               Email:[e-mail]
Networking & Telecommunication Services
Office of Information Technology
University of Minnesota
2218 University Ave SE        Phone: [phone]
Minneapolis, MN 55414-3029   Cell: 612-812-9952
===============================================