[arin-ppml] Routing table growth, was Re: IPv4 is depleted today

Iljitsch van Beijnum iljitsch at muada.com
Wed Sep 3 11:57:22 EDT 2008

On 3 sep 2008, at 17:32, Tom Vest wrote:

>> It's not the cost: it's the benefits. If it costs $50 to implement v4
>> and you can reach 500 sites out of the Alexa top 500, that's $0.10  
>> per
>> destination. If v6 is only $40 but you can only reach the 0.4% of the
>> Alexa top 500 sites that have IPv6 that's $5 per destination.

> The question is, what mechanisms will contribute to increasing that  
> benefit number?

I don't think being able to reach IPv6 destinations in the immediate  
future will drive IPv6 adoption. The driver will be the lack of IPv4  
space for ISPs. They will then have to choose a mechanism to get  
content (which will presumably still be predominately on v4) to their  
users. One way is to do NAT in the ISP network. Another is NAT-PT  
(well, probably NAT64, (hopefully) its successor) and yet another  
"dual stack lite".

I'll assume the first familiar, the second is IPv6 clients talking to  
IPv4 servers through a v6-v4 translator + NAT and the third IPv4  
clients talking through an IPv6 cloud and an IPv4 NAT to an IPv4 server.

The last two both have the advantage that an ISP can support many  
customers behind a big fat NAT box without having to do routing/ 
addressing trickery and there's just the one NAT box. With the first  
solution internal routing and management becomes a nightmare and if  
there are additional NATs peer-to-peer becomes REALLY hard.

So NAT64 and/or dual stack light, along with futureproofness, may be  
what gets IPv6 in the door at ISPs. Then, when the number of IPv6  
eyeballs is sufficiently large, it becomes interesting for content  
providers to talk to those people directly over v6, this helps them  
track people more easily, among other things.

> 1. Incumbent IPv4-based operators altruistically make their own  
> content and services transparently accessible to remote IPv6-only  
> networks,

0.4% of the Alexa top 500...

Note that once we're at about 10% or so IPv6 use, it really doesn't  
matter all that much if it grows beyond that, until we reach 50/50 and  
then, 90%. At that point, people will start turning off IPv4. Between  
10% and 90% we'll have a de facto dual stack internet.

> 2. Topologically adjacent IPv6-only networks grow and proliferate,  
> driven solely by IPv6-based demand for IPv6-based content and  
> services,

Peer-to-peer. I already have IPv6 bittorrent peers regularly these days.

> 3. IPv4 transfer prices and/or outsourced v4/v6 translation services  
> remain low enough so that otherwise IPv6-only networks can exchange  
> traffic with each other remotely without being substantially /  
> differentially disadvantaged relative to IPv4-based incumbents.

I don't understand.

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