Re: [RRG] End user network size [ [Q] draft-farinacci-lisp: IPv4 address depletion]

[Robin Whittle <rw@firstpr.com.au>]

In the absence of a new architecture (LISP/eFIT-APT/Ivip/TRRP), year
by year, X number (X will grow with each year) of end-user networks
will want and/or need stable IPv4 addresses, for the purposes of
multihoming and/or so they can choose ISPs without renumbering.
Without a new architecture, some proportion Y of those networks will
get PI address space, with each such network adding at least one
advertisement to the BGP system.

So without a new architecture, X*Y new advertisements will be added
to the global IPv4 BGP routing table - and each such network will
chew address space in multiples of 256 addresses.  (Of course this
would quickly run into limits due to shortage of fresh address
space, so to the extent that this shortage thwarts the reasonable
needs and desires of end-users - reducing Y - the impact on the
global routing table wouldn't be as bad.)

I don't know what X*Y will be for each year, but the number will
grow and soon be a few hundred thousand or more.

The question is:

  What proportion Z of these end-user networks could be run (in a
  way which reasonably meets the end-user's needs) with
  significantly less than 256 IP addresses?  (Say 128, 64, 32, 16,
  8, 4, 2 or even 1.)


My guess is that the answer would be "quite a large proportion".

This proportion Z will grow over time, since there will be more and
more general pressure to conserve IP addresses, and more development
and acceptance NAT etc. technologies to do this.

Any of the just mentioned new architectural proposals enable the
doling out of stable address space in increments of 128, 64 ... 1 -
for the purposes of multihoming and of choosing a new ISP without
renumbering.

X will grow forever.  Z will grow over time.

So X*Y*Z can be expected to grow to a large enough number within a
few years that I think it is fair to say that any of these new
architectures could and should make a significant contribution to
the more efficient use of IPv4 address space.  That won't resolve
the address shortage, but it will provide much-needed benefits.


Through no fault of its own, I can't see how IPv6 will be widely
adopted in the foreseeable future.  IPv4 was not designed to
facilitate migration to any other system.

I think the IPv4 address crunch will just lead to more and more
inventive ways of using address space efficiently.  Without a new
architecture, this will surely bloat the IPv4 global routing table
to double and beyond its current size in a few years.

No-one will be happy with an IPv6-only address until 99% or more of
other Internet users have an IPv6 address too.  There seems to be
little reason to get an IPv6 address at present, for most people,
and I can't see why this would change.

I think we are still going to be clamouring for IPv4 addresses in
ten or fifteen years time.  Maybe we will be stuck with it forever.
 I hope a new routing and addressing architecture can be implemented
around 2012.

 - Robin


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