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Re: Generic anycast addresses...

Toerless Eckert <tte@cs.fau.de> Thu, 30 May 2019 20:39 UTC

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Date: Thu, 30 May 2019 22:39:18 +0200
From: Toerless Eckert <tte@cs.fau.de>
To: Michael Richardson <mcr+ietf@sandelman.ca>
Cc: "6man@ietf.org" <6man@ietf.org>
Subject: Re: Generic anycast addresses...
Message-ID: <20190530203918.tga5sntyywg35e3h@faui48f.informatik.uni-erlangen.de>
References: <BN6PR21MB04978DB375C05CB3CE4C914EA31F0@BN6PR21MB0497.namprd21.prod.outlook.com> <4EF97F31-1F39-4150-B044-955C46E96FB4@fugue.com> <20190530002833.wfvjfbj2lv2ig664@faui48f.informatik.uni-erlangen.de> <7A9560FC-0393-45DF-8389-B868455AC6DD@fugue.com> <20190530005734.7d2alod2zoaemmhc@faui48f.informatik.uni-erlangen.de> <D6E27B45-437F-45BE-A305-47DD460BCE02@fugue.com> <26144.1559226966@localhost> <1DD451A7-D898-4105-974C-53776A3DA9F2@fugue.com> <20190530152902.l2nmyhadr4e4kt7x@faui48f.informatik.uni-erlangen.de> <32061.1559243459@localhost>
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On Thu, May 30, 2019 at 03:10:59PM -0400, Michael Richardson wrote:
> 
> Toerless Eckert <tte@cs.fau.de> wrote:
>     >> That seems reasonable.  Even if at some point we want to have a
>     >> mechanism for allocating ULAs globally, this would just be one that was
>     >> allocated globally.
> 
>     > I still haven't seen an argument why this anycast scoped app could not
>     > simply use an existing ULA prefix. AFAIK, there is nothing prohibiting
> 
> there are three reasons I can give:
> 1) it won't be distinguishable

None of the current uses of anycast is and that hasn't been a problem.

> 2) there is some small chance that someone will pick that /48 for it's use.

Thats the problem between any two independent ssignments of ULA space,
but that hasn't stopped ULA space to be defined.

> 3) we won't be able to give it intelligent reverse DNS and whois (which we
>    *can* with ULA-C or some other GUA space)

AFAIK you can not have multiple zones with the same address(es) if you
want reverse DNS lookup. So you can not use well-known/hard-coded
anycast addresses but need again to first do another
lookup/resolution/algo to figure out your local sites Anycast address(/prefix).

Cheers
    Toerless

> --
> ]               Never tell me the odds!                 | ipv6 mesh networks [
> ]   Michael Richardson, Sandelman Software Works        |    IoT architect   [
> ]     mcr@sandelman.ca  http://www.sandelman.ca/        |   ruby on rails    [
> 
> 
> --
> Michael Richardson <mcr+IETF@sandelman.ca>, Sandelman Software Works
>  -= IPv6 IoT consulting =-

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