Hi Paul,

>> A) "The Internet continuing down the current architectural path,
>>    whereby site multi-homing increases the size/entropy of the
>>    DFZ RIB/FIB is not believed to be scalable or viable."
> 
> (e.g. Geoff Huston's more recent BGP reports seem to show evidence
> that BGP is more stable than expected in the face of how the internet
> is growing).


Are you referring to Geoff's recent APRICOT talk on "BGP in 2009"?  If so,
that would seem to indicate convergence times for single prefixes are
relatively stable and seem to be proportional to AS path length.  It is not
terribly surprising that these are constant, as a significant fraction of
changes are due to tail circuit changes where only a small number of
prefixes are actually going to shift paths.  Since BGP convergence at a
single node is going to take time that is linear in the number of affected
prefixes, and only a few prefixes are changing, there would seem to be
nearly a constant amount of work to do.

That same talk reinforces the fact that we're still on a quadratic growth
curve, for both v4 and v6.  ;-(

What I didn't see in there was any discussion of the convergence time when
there is a point failure in the network, such as when a router reboots.
These are the cases where the BGP convergence time is going to be linear in
the number of prefixes.

Or, put another way, Geoff's work suggests that routers in the middle of the
net aren't rebooting frequently.  Whew.  ;-)

Regards,
Tony


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