At 02:28 AM 12/17/2000 -0500, J. Noel Chiappa wrote:
To put it another way, let's imagine an alternate reality in which IPv4 had
48-bit addresses - enough so pretty much everyone could get as many as they
wanted, and nobody used NAT boxes because they couldn't get enough addresses.
Now, think about what the routing table would look like in that alternative
reality. I expect it would have pretty much the same number of entries as we
do now - but on average, each entry would be "bigger".
In other words, the routing system may be running into problems, but those
problems have basically nothing to do with the address space shortage, and the
measures taken to deal with it (i.e. NAT). (I'll leave unstated the obvious
corollary - I'm sure Perry will figure it out! :-)
I'm with you in that I do not see a causal relationship between the
availability and deployment of NATs and the increase in routing table size.
However, I do think that there is a definite causal relationship between
the address space shortage and the number of prefixes in the routing tables.
People who allocate addresses (registries and ISPs) use slow-start
algorithms in their allocation policies due to the shortage of addresses.
Therefore many organizations end up announcing several non-aggregatable
prefixes which they have acquired over time.
If we did have an address space where "pretty much everyone could get as
many [addresses] as they wanted," there would be fewer prefixes in the
routing tables. If everyone could get "enough" addresses the first time,
we'd be much closer to the ideal of one prefix per AS.
Bradley