Re: [RRG] IPv4 shortage, new features and IPv6 inevitability

["Tom Petch" <nwnetworks@dial.pipex.com>]

----- Original Message -----
From: "Iljitsch van Beijnum" <iljitsch@muada.com>
To: "Robin Whittle" <rw@firstpr.com.au>
Cc: "Routing Research Group list" <rrg@psg.com>
Sent: Thursday, November 22, 2007 11:22 AM
Subject: Re: [RRG] IPv4 shortage, new features and IPv6 inevitability


> On 22 nov 2007, at 4:59, Robin Whittle wrote:
>
<snip>

> You assume a model where it would be possible for every device that
> connects to the network to get an individual public address. That's
> simply not possible with IPv4, because the need for addresses is so
> dynamic that ISPs can't realistically provision addresses this way.
> (For instance, currently I don't need any addresses at home. When I
> get home and start copying some data between different computers I
> need 4 or 5 addresses.)
>
> The current model is that in most cases, an ISP provisions one address
> per line to a customer. If this changes to a larger number of lines
> per address this makes NAT more problematic for end-users, but yes,
> that could save a lot of address space.
>
> > It is not meaningless.  My survey and the much better work at USC ISI:
>
> >  http://www.isi.edu/ant/address/
> >  http://www.firstpr.com.au/ip/host-density-per-prefix/
>
> > both surveyed address space which was advertised in BGP.
>
> I asked the guy from ANT, he said that they also pinged unrouted space.
>
> > Geoff Huston estimates 5 to 20% utilization.
>
> Could be. I'm pretty sure that many ISPs never bother to reuse old
> address space when customers leave etc but simply request new stuff.
>
> The real question is: why is the utilization so low? And is that
> reason still present today? If so, what would we need to do to
> overcome that factor? And if we do that, how much extra IPv4 time
> would that give us?
>
<snip>

What strikes me is that I - we? - really have no idea why IP addresses are
needed.  We can see who has the allocations, we can follow (and shape) the
policy for this, but I do not see why the number of addresses in use is rising
and I think it matters because the 'why' will affect predictions of future
growth.

If, for example, it is because addresses are being used to provide dial-up
access for new users in India and China, then clearly there is a latent demand
in the billions, which will continue for decades.

If instead it is because of the recent mass migration from dial-up to
broad-band, from a contended-for pool to a permanent /30 per potential user  -
and there is as much evidence to support this hypothesis as there is of the
widespread adoption of IPv6 - then this is a temporary phenomenon and the demand
will dry up in a few more years.

I really don't know (and see it as significant to the debate); does anyone?

Tom Petch


--
to unsubscribe send a message to rrg-request@psg.com with the
word 'unsubscribe' in a single line as the message text body.
archive: <http://psg.com/lists/rrg/> & ftp://psg.com/pub/lists/rrg