----- Original Message ----- From: "Iljitsch van Beijnum" <[EMAIL PROTECTED]> To: "Robin Whittle" <[EMAIL PROTECTED]> Cc: "Routing Research Group list" <[email protected]> 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 [EMAIL PROTECTED] 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
