[rrg] Summary of architectural solution space

[William Herrin]

On Thu, Dec 4, 2008 at 11:36 AM, Teco Boot <teco at inf-net.nl> wrote:
> On Strategy G:
>>> Make everybody attach to only one ISP using IPv6 and the ISP's single set
> of PA addresses, as originally intended for IPv6.
> Can you provide a xref for this statement?
> RFC1887 describes 4 solutions for Multi-homed Routing Domains (section 4.4).

Hi Teco,

I was being sarcastic and a little condescending. I should probably
rewrite it more like RFC 1987 4.4.3  and move the sarcasm to the
criticisms section.


RFC 1887 4.4.1 is strategy F: do nothing.

RFC 1887 4.4.2 is obviously not functional with *currently deployed
network stacks*. It would need the kind of software described in
strategy B or H in order to be viable. Or do you disagree?

RFC 1887 4.4.3 turns into strategy G once you actually fill in the
details. Hence my condescension.

RFC 1887 4.4.4 is knuckleheaded. You want to avoid a dependence on one
ISP so you get another ISP who won't work except by sending traffic
through the first ISP? Seriously? It doesn't belong in the solution
domain.



> On Strategy B and H:
> I think the difference of the two strategies is minor. Make methods A2a and
> A2b for these?

I vacillated on that for a while and eventually came down on the side
of calling it a different strategy. I think if the difference was
truly minor, IPv6 would have worked out a whole lot better than it
has.



> And on the criticisms:
> With B: Why would LOCs be constantly in flux? Fixing this should be part of
> the strategy.

Because link state changes on the nearby upstream path are satisfied
by renumbering instead of rerouting. When I said "dynamic," I really
really meant it.

Actually, that's not strictly true. You'd reroute for a few minutes,
long enough to be sure the state change wasn't ephemeral. Then you'd
renumber and on completion discontinue the exception route. That's
because renumbering looks like a distance-vector protocol; I can't
think of a way to describe it as a faster link-state protocol.

Regards,
Bill Herrin


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