If it isn't an address issue, is it a routing issue? Is it that the
routing tables/protocols/hardware can't handle the large number of
routes? Are ISPs refusing to carry reasonable routes? Seems to me if
the entire address space was broken up into subnets of 4096, there
would be about 1 million routes. What is the current size? I think I
remember seeing numbers on the order of 50,000.
Current size as of a few months ago was 85k routes.
correct. Now its pushing around 100,000, That's a relatively steep
growth curve. (www.telstra.net/ops/bgp)
The rate of growth in the table and the prefix length distribution
in the table both point to the growth of small prefixes (/24)
as a major factor in the growth of the routing table.
There are strong indications that NAT is one factor behind this
part of the BGP table.
Now I'm not saying that this is either good or bad - what is evident
is that much of the recent growth in the deployed Internet has happened
behind NATs of various forms and the side effect is low levels of overall
address space growth as reflected in the span of address space advertised
in the BGP tables, but an increasing finer level of granularity in the
routing table. There are of course other factors also at play which
are causing the same outcomes, so NAT is not the only driver.
So its not NATS *are* evil - NATs are very commonly used these
days and we simply cannot deny their existence nor condemn their
use as unworkable. NATs are a *compromise* - some folk find the compromise
unacceptable - others do not. These days out there in the network as
my bgp table sees it, a large number of folk find NATs a comfortable
I won't speculate whether these folk are making a fully informed decision
or not - the BGP table has no such data embedded in it that can
be reliably interpreted.