Subject: RE: draft-kurtis-multihoming-longprefix comments

From: "J. Noel Chiappa" <[email-masked]>
Date: Tue, 7 Jan 2003 16:38:08 -0500

> From: Iljitsch van Beijnum <[email-masked]>

    >> The current routing technology does NOT scale properly. There is not
    >> going to be any intermeidate approach based on the current technology
    >> that will scale.

    > With a reasonable level of aggregation current technology will scale
    > just fine.

I think Tony's talking about routing protocols, not hardware.

In any case, I too will disagree with Tony, and say that no possible routing
technology can scale as well as some people would like it to. :-)

    > Today, if routers are owned by the same owner, they hold the same
    > routing information. Maybe it's time we try aggregating based on
    > something else than router ownership.

Reading this, I literally had to cringe and hold my head in my hands.

The *only* way to aggregate *which is useful to the routing* is based on
*actual connectivity* - i.e. the actual ability send packets. Ownership of box
X and box Y is basically irrelevent (although policty routing may use it for
*additional* constraints), from the routing's point of view. If box X and box
Y are connected by a wire - now, that's different.

	Noel

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From: Iljitsch van Beijnum <[email-masked]>
Date: Tue, 7 Jan 2003 23:26:19 +0100 (CET)

> Reading this, I literally had to cringe and hold my head in my hands.

:-)

> Y are connected by a wire - now, that's different.

Suppose ASes 1, 2, 3 and 4 are all present with one router in Chicago,
NYC, Dallas and LA and they all interconnect there. Each router has 100
customer routes. So you can aggregate and have 400 internal and 3
external routes in each AS. Or you can do geo aggregation as per my
draft and have 400 LA routes regardless of which ISP each route belongs
to in LA, 400 Chicago routes in Chicago and so on and 3 pilot routes to
other locations. So it's exactly the same thing, only in this case you
can aggregate multihomers.

Now obviously in the real world interconnection between regions within
an ISP network is denser than between ISP networks within regions, but
regional interconnection is still dense enough to make it worth the
trouble.

But in the mean time I'm working on a multiple address draft which is of
course much cooler but upgrading all hosts in the world also has its
problems...

Iljitsch

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From: Pekka Savola <[email-masked]>
Date: Wed, 8 Jan 2003 01:00:48 +0200 (EET)

On Tue, 7 Jan 2003, Iljitsch van Beijnum wrote:
> external routes in each AS. [...]

Is this for real?

If you can assume some sane address plan which provides aggregation, each
AS would have about 7 routes in each router plus 100 local routes in each.
There is idea use passing the customer routes even in internal routing if
you can aggregate.  Ideally these kind of static routes are just a problem
of a single aggregation device.

Just to be sure we're not comparing apples to oranges..

-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings

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From: Iljitsch van Beijnum <[email-masked]>
Date: Wed, 8 Jan 2003 00:11:46 +0100 (CET)

On Wed, 8 Jan 2003, Pekka Savola wrote:

> > Each router has 100

> AS would have about 7 routes in each router plus 100 local routes in each.

In IPv4 that's not going to happen as it wastes too much address space.
I'm not sure how strict the RIRs are with IPv6 space, but it looks to me
they are still in the process of wrapping their minds around 128 bits.
(Think about it: 64 bits is enough to give every square millimeter of
earth surface an address.)

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From: Kurt Erik Lindqvist <[email-masked]>
Date: Fri, 10 Jan 2003 17:03:51 +0100

> earth surface an address.)

Then think that is not that long ago the address efficiency usage was 
around 4% (I might remember this incorrect but I have a vague feeling 
we where around that at pre-CIDR).  I think that the last figure I saw 
was at around 35-40%. It's still not that impressive, but also very 
hard to get much better (Without research in the field I would assume 
that 60% would be close to a practical/theoretical maximum limit (is 
there any research done in this field?).

- kurtis -

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From: Kurt Erik Lindqvist <[email-masked]>
Date: Fri, 10 Jan 2003 16:59:35 +0100

> regional interconnection is still dense enough to make it worth the

You are touching on one of the areas that makes me think twice about 
geo-aggregation and that is intra-operator routing and policy. It's not 
insolvable, and I will not make the claim that I understand this fully 
(on the contrary, I am just a hang-around..:) ), but it makes some of 
the night-mare set-ups I have seen so far look even worse. Then again, 
there is a lot out there that we need to clean up anyway....

> course much cooler but upgrading all hosts in the world also has its

Well, as discussed in Atlanta, I don't think we will come down with a 
"one-solution-fit-all". Sorry.

- kurtis -

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From: Iljitsch van Beijnum <[email-masked]>
Date: Sun, 12 Jan 2003 16:36:00 +0100 (CET)

> geo-aggregation and that is intra-operator routing and policy.

Read the draft, this issue is addressed and should not be a problem.

Iljitsch