Dampening is part of the protocol and has nothing to do with the speed
of light.
Well, not really. Assume a simplistic model of the Internet with M
"core" routers (in the default free zone) and N "leaf" AS, i.e. networks
that have their own non-aggregated prefix. Now, assume that each of the
leaf AS has a "routing event" with a basic frequency, F. Without
dampening, each core router would see each of these events with that
same frequency, F. Each router would thus see O(N*F) events per second.
Since events imply some overhead in processing, message passing, etc,
one can assume that at any given point in time there is a limit to what
a router can swallow. In either N or F is too large, the router is
cooked. Hence dampening at a rate D, so that N*F/D remains lower than
the acceptable limit.
Bottom line, you can only increase the number of routes if you are ready
to dampen more aggressively. There is an obvious "tragedy of the
commons" here: if more network want to "multi-home" and be declared in
the core, then more aggressive dampening will be required, and each of
the "multi-homed" networks will suffer from less precise routing, longer
time to correct outages, etc.
There are different elements at play that also limit the number of core
routers. Basically, an event in a core router affects all the path that
go through it, which depending on the structure of the graph is
somewhere between O(M*log(M)) or O(M.log(M)). In short, the routing load
grows much faster than linearly with the number of core routers.
-- Christian Huitema
_______________________________________________
Ietf mailing list
Ietf(_at_)ietf(_dot_)org
https://www1.ietf.org/mailman/listinfo/ietf