Re: [rrg] Locator: routing scalability

[Paul Jakma <[e-mail]>]

On Thu, 14 May 2009, Toni Stoev wrote:

> Does locator have to facilitate routing with its structure?
> My answer is: yes, it must.

I have a question, a stupid one probably... Is the following thinking 
of mine correct?:

If we encode routing information into the locator somehow, then this 
implies the 2 are tied together, and that (at least) the initial 
top-level hierarchy of internet routing is fixed for the life-time of 
the locator. So this implies either one or more of:

- that the lifetime of locators be short, and that they are
   re-calculated/re-assigned frequently enough to have a sufficient
   level of reachability between hosts on the internet.

   (e.g. imagine a scheme that assigned locators empirically, by
    examining the structure of the internet and calculating a
    spanning-tree that approximated a power-law distribution
    as good as possible and then assigning locators in an according
    fashion, thus maximising the aggregation of routing information.

    I think there may be papers describing such things, but I'm not
    sure there are RRG proposals ???).

- fairly long-lived, indeed static locator assignments. This implies
   a quite broad and flat, top-level routing table. This is basically
   what we have today, if ASes advertised just one prefix.

   Proposals under this model generally split routing into a 2-tier
   system: the flat, top-level routing table + a secondary table of
   networks behind the top-level locators (either aggregated locators,
   or remapped/tunneled somehow)

Is this right so far?

If so, and if the prevailing proposals so far are of the static 
top-level kind, then do know if a flat top-level is sufficiently 
scalable? Is there any data/work on how fast this top-level might 
grow? To what extent is the AS growth reflective of how that 
top-level might grow? To what extent is the transit-AS growth 
reflective of it?

I ask because AS growth might not be linear:

 	http://www.potaroo.net/tools/asn32/

though transit-AS growth is unclear (it doesn't grow much in fact, so 
its perhaps impossible to get a trend from it):

 	http://www.potaroo.net/ispcol/2009-03/bgp2008.html

Basically, what I wonder is whether a static top-level 
locator->routing mapping is sufficient to meet the scaleability 
requirement?

If it is not, then facilitating routing with the locator is just a 
delaying tactic - a more dynamic system would eventually be 
necessary.

If it is sufficient, great, of course - any dynamic system would by 
definition be more complex.

(There may be ways of statically assigning locators according to some 
kind of power-law distribution - but this means impressing some kind 
of order onto ISPs, which probably isn't socio-politically 
tractable).

regards,
-- 
Paul Jakma	[e-mail]	[e-mail]	Key ID: 64A2FF6A
Fortune:
Neutrinos are into physicists.