When will 128M not be enough?

Wed Jul 18 03:09:53 UTC 2001

> Two factors appear to be at play at present:
> 
> 1 - there has been an effort by many AS's to reduce the number of address
> fragments advertised into the global routing tables. The 'noise' in the
> routing table is being reduced (slightly)
> 
> 2 - there is some slowdown in overall Internet growth in terms of a) the
> number of new AS's being added into the global routing table and b) the
> total span of address space being announced into the global routing table.
> Either this is an effect of an economic condition (most likely) or a number
> of folk at the edge are increasing their use of NAT and are disappearing
> behind the NAT boxes (less likely,but also possible).

There is a third force behind this -- one that I've rarely seen mentioned
here. It's called entropy.

Of course, actual new autonomous systems appear all the time, needing new AS
numbers. Likewise, the number of actual hosts on the Internet is increasing,
justifying the need for new IP addresses.

But I'd venture to guess that most of the increase in AS numbers and routes
is because of increasing entropy on the Internet. We are losing those
resources to natural inefficiency.

It should be noted that aggregation is only part of the story; while it can
reduce the number of advertised prefixes (usually just once!), it can not
turn back the passage of time. And time introduces routing table bloat -- by
introducing situations that make aggregation impractical or impossible.

Case in point: an ISP merger or acquisition, something very common in this
quickly consolidating business. You end up with two AS numbers (at minimum)
and two sets of netblocks. Because of practical reasons, those assets may be
combined into one in a) a week b) a month c) a year d) never. The recent
example of Exodus and GlobalCenter is, to my understanding, a good one,
since they are renumbering. This seems to be an exception to the rule,
though.

I can't see anything else changing this than mandary, RIR-enforced
renumbering. My company is a member of RIPE, and the spectre of mandatory
renumbering *is* flashed in the RIPE documents -- I'm just enough of a
novice to never have seen or heard it happen. Does it?

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