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Re: What is the limit? (was RE: multi-homing fixes)

  • From: Leo Bicknell
  • Date: Wed Aug 29 11:37:24 2001

On Wed, Aug 29, 2001 at 08:05:51AM -0700, Sean M. Doran wrote:
>   The global routing table size HAS grown exponentially 
> in the past.   Rationalize it any way you want, blame whatever
> you like, but there is no known way to construct a router that
> can handle that kind of growth in anything but a short term,
> and the trend for the components in the router growth curve
> is simply not going to increase to a long term superlinear rate.

Ah, but exponential growth can't happen forever, and we can build
a system to handle the largest possible Internet (with v4, anyway).

If you had a router that could handle 2^32 prefixes, it will handle
the IPv4 Internet.  Forever.  The whole growth curve argument is

The global routing table cannot grow exponentially forever.  There
are upper bounds all around, including but not limited to the number
of addresses.  Over time the growth curve must change to be linear,
and then logarithmic..

For reference, there are approximately 10^80 electrons in the
universe (per several physics sources I found on the net).  At
doubling every year that gives us an absolute upper bound of 265
years, if every route could be stored in a single electron.  Figuring
we can probably only do one per atom, and averaging 4 electrons
per atom (is that high or low?) that gives us 106 years.  We're 30
years into this IP thing, roughly, so we're 1/3 of the way there.

Not to minimze the short term issue, but to hand wave and say
"it's exponential and we'll never get ahead of it" is crap.  It
won't be forever, so let's get ahead of it.

Leo Bicknell - [email protected]
Systems Engineer - Internetworking Engineer - CCIE 3440
Read TMBG List - [email protected],