Re: [RRG] Idea for shooting down

["Tom Petch" <nwnetworks@dial.pipex.com>]

----- Original Message -----
From: "Brian E Carpenter" <brian.e.carpenter@gmail.com>
To: "Iljitsch van Beijnum" <iljitsch@muada.com>
Cc: "RRG" <rrg@psg.com>
Sent: Thursday, November 22, 2007 9:59 PM
Subject: Re: [RRG] Idea for shooting down

> On 2007-11-23 01:13, Iljitsch van Beijnum wrote:
> > On 19 nov 2007, at 22:59, Brian E Carpenter wrote:
> >
> >> http://www.cs.auckland.ac.nz/~brian/DFZng.pdf
> >
> > I don't understand how this works... Would ISPs at each level aggregate
> > the address prefixes used at the level below, or would addressing be
> > completely separate from the hierarchy so some kind of
> > mapping/encapsulation would need to happen?
>
> The second case. There would not only be a separate instantiation of
> BGP4 in each region, but also a separate instantiation of (e.g.)
> LISP-ALT. The idea is to recurse the whole model (EGP and locator-locator
> mapping). ((Er, LISP EIDs are a special case of locator as far as
> I'm concerned.))
>
> I realise it's badly explained, but it seems quite hard to explain
> clearly.

For once, I think the .pdf explains it clearly (or perhaps I do not
understand:-)

I think that every scheme proposed, and every scheme that will be proposed, is
based on a heirarchy in some abstract sense and that the feature of this one is
to use AFI to 'expand' the IP address range, and to allow multiple levels.

I wonder about router capacity, that is that the Internet only works because
routers are incredibly fast at 'parsing' IPv4 addresses and I think that that is
the inherent nature of an IP address, rather than because ASICs have been
optimised for that task.  So what I wonder about is the speed of routers at the
transition from s+x flat routing to the next level down, s+x-1; an alternative
could be to put the equivalent of the AFI bits into the middle of an IPv6
address (howls of protest) with an IPv4 address in the lower order bits, so
preserving the single bit-structure to parse.

My other thought is the political one, that ISPs have had a fairly free rein to
place points of presence where they will, unconstrained by the sorts of
considerations of Internet technology that drive these discussions, and that
some day they may (will?) have to change and accept that eg because they are in
a particular location, then they must aggregate in a certain way and use a
certain transit to access the rest of the world.

Tom Petch

> Since I won't be in Vancouver, I will try to come up with
> a better description and more diagrams at some point.
>
>     Brian


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