Subject: Re: [GROW] Call for GROW WG adoption of grow-overlapping-routes

From: [email-masked] (Noel Chiappa)
Date: Thu, 30 Aug 2012 21:32:29 -0400 (EDT)

> From: Robert Raszuk <[email-masked]>

    > even those proposed just push the issue to a mapping plane 

I did say that doing TE in a mapping would not be as good as an upgraded,
modern routing architecture (one suited to a global-scale information network
- but let's not get me started on that rant) that had TE capabilities built
into it... _but_ using the mapping plane is still much better than using
more-specifics.

Just like doing multi-homing by injecting routes into the global
destination-vector routing is just about the worst way to support MH, same
thing for TE. Every router in the entire default-free core has to dedicate a
routing table slot to each more-specific - and not just that, it's not just
table entries, there's also routing system overhead to maintain it (CPU, etc,
etc).

If you do it in a mapping plane the only people who have to pay the overhead
are the people _who actually talk to that destination_ - not everyone in the
whole world. Does this not sound like a fairer way to support this?

	Noel

---

From: Nick Hilliard <[email-masked]>
Date: Fri, 31 Aug 2012 10:10:55 +0100

On 31/08/2012 02:32, Noel Chiappa wrote:
> destination-vector routing is just about the worst way to support MH,

reminds me of that saying: "... democracy is the worst form of government
except all the others that have been tried."

No-one's going to argue that multihoming by multiple prefix announcement
isn't a pile of poo.  It's just that all that all the alternatives are even
worse.  At least multihoming by multiple prefix announcement is simple and
has well-understood problems and failure modes.  All the alternatives are
significantly more complicated in a variety of different ways, and all open
up many more and many more complicated failure modes.

Re: the draft, I don't think it should be adopted by the WG unless the
authors can provide analysis showing that it doesn't fail in the two modes
which were mentioned on the list in the last couple of days.

Nick