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 [email protected] [email protected] Key ID: 64A2FF6A
Fortune:
Neutrinos are into physicists.
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