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Re: Generic anycast addresses...

Michael Richardson <mcr+ietf@sandelman.ca> Thu, 30 May 2019 14:30 UTC

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From: Michael Richardson <mcr+ietf@sandelman.ca>
To: Ted Lemon <mellon@fugue.com>
cc: Dave Thaler <dthaler@microsoft.com>, "6man@ietf.org" <6man@ietf.org>
Subject: Re: Generic anycast addresses...
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Date: Thu, 30 May 2019 10:30:12 -0400
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Ted Lemon <mellon@fugue.com> wrote:
    > Unfortunately this document doesn’t really talk about the use case I’m
    > referring to.   We did talk about doing this for DNS and for PCP, but
    > neither of those proposals ever got the point of actually wanting to do
    > something.   I don’t think what I’m talking about is novel, but it
    > appears that not only hasn’t it caught on, but it’s not even really
    > talked about in the places where one might wish for it to be talked
    > about.

RFC7084 points out:

   Anycast addresses are syntactically indistinguishable from unicast
   addresses.  Anycast addressing is equivalent to that of unicast in
   multiple locations.

and I think you want an address which is synatically distinguishable from
unicast.  Maybe something that does not get caught by default route; although
I'm not sure about that.

Maybe we could have hacked in what you want into site-local space, but that's deprecated.
I don't think it can go into link-local space.

In the case where the service is not available in the homenet/campus, where
would the packet get discarded?   Maybe this could be done in an IANA
allocated /48 that we all agree to blackhole route on the DFZ, but this seems
like it might be a hack.

--
Michael Richardson <mcr+IETF@sandelman.ca>, Sandelman Software Works
 -= IPv6 IoT consulting =-

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