On Sat, 13 Mar 2010, Robin Whittle wrote:

Geoff's research is:

In the "Re: [rrg] draft-narten-radir-problem-statement-05.txt" thread

and in "BGP in 2009":

Those are the ones. I'd read that email too, but had forgotten of its existence in replying to this thread - thanks for highlighting it.

 It's possible that the current architecture of the internet is
 holding back growth that should otherwise be there.

Yes.  If we concentrate only on non-mobile networks, there are two
broad aspects of the routing scaling problem:

 1 - The unreasonable, arguably unscalable, burden placed on the
     DFZ routers individually, and on the DFZ control plane in
     general, by the set of end-user networks which currently
     get portability, multihoming and inbound TE by the only
     means available: getting their own space and advertising it
     as PI prefixes in the DFZ.

Well, why is it "unreasonable" exactly? If the system works and is scalable, what's the problem?

It's only unreasonable if there's a /good/ way to keep those prefixes out of the DFZ (i.e. good in the sense that it's at least as good as what we have today). If such a way exists, then that's great - we should definitely research ways to improve routing, of course.

However, it does not seem justified to say the current routing architecture has a scaling problem. So it would not be justified, at thhis time (AFAICT), to excuse inefficiencies added by proposed changes on the basis that there's a pressing problem with the current architecture.

 2 - The much larger number of end-user networks which could use 2
     or more ISPs and which want or need portability, multihoming or
     inbound TE but don't have it because they are unable to get the
     space and advertise it.  (Perhaps a subset of these could do
     it, but don't because they known how unscalable it is.)

The growth in BGP advertised PI prefixes is the simplest measure of the first aspect - which is like the tip of the iceberg. The less visible part is point 2, like the main body of the iceberg.

Well, the internet is going to grow. That's hardly a surprise. What's the problem with the internet growing? Geoff's results seem to show that the growth is well within the scaling abilities of the 'net.

So even if Moore's Law keeps up in some acceptable manner with the pace of growth in the number of PI prefixes in the DFZ, this doesn't help with point 2 or with mobility.

Sure, but:

a) If the scope of the problem suddenly is "those very small
   networks which want portability/multi-homing but aren't big enough
   to get an AS and PI", then:

   - it's a much, much smaller problem in terms of affected parties
     than "internet routing doesn't scale"

   - it's not clear even that such networks exist to any
     meaningful extent (OK, I'm geeky enough that I'd love portability
     and multihoming for my home network), i.e. if this is the
     problem being solved then that changes the economic incentives
     of roll-out.

b) If the problem is that fewer networks today can get PI, then we
   should be able to see a change in the mode of prefix growth in the
   historical data. However, TTBOMLK, we don't see this in the data.

Basically, if there's a problem then where is the evidence of it, now that we seem to have initial evidence to suggest otherwise?

Sorry I haven't had time to revisit our discussions in early February. I have a backlog of RRG messages to read and respond to - mainly discussion following from my critiques of several architectures - and I need to give priority to paying work.

No worries, that was just speculation on my part anyway. :)

Paul Jakma      p...@jakma.org  Key ID: 64A2FF6A
If you don't have a nasty obituary you probably didn't matter.
                -- Freeman Dyson
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