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Re: Generic anycast addresses...

Michael Richardson <mcr+ietf@sandelman.ca> Fri, 31 May 2019 15:49 UTC

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From: Michael Richardson <mcr+ietf@sandelman.ca>
To: Ted Lemon <mellon@fugue.com>, "6man@ietf.org" <6man@ietf.org>
Subject: Re: Generic anycast addresses...
In-Reply-To: <D648647D-60E1-4DCE-B0BE-11002E0AE5A4@fugue.com>
References: <D22E680C-3EE3-4AD7-90C0-9339DA2E5A29@fugue.com> <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> <0FF19D6D-1A45-41EF-BE34-CC35B5E51E1E@steffann.nl> <D91629F6-73AC-4A80-80EF-16644F73DA36@fugue.com> <701687d4-842c-6a16-3c97-349125324e3f@gmail.com> <D648647D-60E1-4DCE-B0BE-11002E0AE5A4@fugue.com>
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Date: Fri, 31 May 2019 11:48:58 -0400
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Ted Lemon <mellon@fugue.com> wrote:
    > On May 30, 2019, at 2:19 PM, Brian E Carpenter <brian.e.carpenter@gmail.com> wrote:
    >> Ted, please do think about the main point: "the fuzzy nature of the
    >> site concept". (And, shameless plug, see
    >> https://tools.ietf.org/html/draft-carpenter-limited-domains
    >> <https://tools.ietf.org/html/draft-carpenter-limited-domains>). Limited
    >> scope anycast needs a non-fuzzy scope boundary.

    > Do ULAs have a non-fuzzy scope boundary?   Serious question—I actually
    > do not know how this is handled in the network.

I'm not sure I a non-fuzzy definition of a non-fuzzy boundary ;-)

When I ping/traceroute ULAs from my home network, they die !N at my ISP's DFZ
machine:

   lando-[~] mcr 10005 %traceroute6 fd2e:82a1:f3c4::1
   traceroute to fd2e:82a1:f3c4::1 (fd2e:82a1:f3c4::1), 30 hops max, 80 byte packets
   1  2abc:efgh:f:2::241 (2abc:efgh:f:2::241)  0.521 ms  0.517 ms  0.508 ms
   2  2abc:efgh:9:8:209:87:239:232 (2abc:efgh:9:8:209:87:239:232)  13.113 ms
   3  2001:550:2:8::ab:1 (2001:550:2:8::ab:1)  32.078 ms !N  32.618 ms !N

hop 1 is the router at home, and hope 2 is the access router at my ISP, and
hop 3 is my ISP's core router connect to upstream peers.

Should hop 1 (home router) or hop 2 (access node) were to blackhole route
fc00::/6 (ULA-R and ULA-C), would that affect your use case?  Or could the
anycast service possibly be at the ISP?

On a campus situation, I would assume that ULA, if used, should be routed to
the all edges, but not beyond.   Or alternatively, consider an ISP+plus it's
customers to be a "campus", or "admin-scope".

Should home routers install routes to 2000::/3 when they see "default" rather
than "::/0"?  I have made that argument, but I see the other point about
how limiting it could be in the future.

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

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