[arin-ppml] IPv6 adoption, map-encap for IPv4?

Robin Whittle rw at firstpr.com.au
Sat Jun 14 04:12:19 EDT 2008

Hi Dan,

Thanks very much for your message, in which you wrote:

> I hope you make it to the ARIN meeting in LA this fall, and have
> a chance to talk directly to many of the people on this list.
> These are discussions that should continue.

That would be great, but I don't work for a big company and am based
in Melbourne, Australia.

> As I've been reading this thread, however I can't get past two
> concepts. These are that you are of the opinion the IPv4 Internet
> is underutilized because experiments can only ping ~100 million
> IP. The other is that IPv6 deployment is a failure because its not
> already deployed.

IPv6 may well be widely adopted at some time.  I just think the
transition arrangements are a shambles and that it is a very long
way from being widely adopted.  I think the chicken and egg problem
is far to big and that there is great scope for keeping most
customers on IPv4, albeit in an increasingly ugly way if it involves
less capable or multi-layer NAT.

> People continue to think that someone will be able to "see" the
> whole (I)nternet. That it is a static, while growing, thing that
> can be mapped. Since everyone likes to use Comcast as a
> reference, here are some facts. Comcast has more than 38 million
> active interfaces using RIR allocated IP addresses. If you factor
> in re-use of private networks, another 35 million IP are being
> used of RFC1918 space. Your thoughts on utilization would imply
> that Comcast makes up around 37% of the Internet. 

The question is to what extent the ping figures underestimate the
real figure of utilization, full or part time, of IPv4 addresses.  I
wasn't suggesting the real figure is close to the ping figure.  I
wrote I guess it was 1.5 to 2 times this figure, but have pointed to
this discussion and changed my guesstimate to 3 to 5:


> I can't speak
> with authority, but I'm quite confident that is not the case.
> Also keep in mind what you consider "utilized". If you have a
> VLAN with a /26, and 50 interfaces connected, are the 50 IP 
> utilized, or are all 64 now unusable anywhere else on the
> network. The 38 million number I quote does not include subnet
> loss, aggregation, capacity maintenance, or deployment plans.
> Also consider, we have had arrangements with other providers,
> where we routed RFC1918 space outside our AS boundries. My point
> to this paragraph is simply the Internet is much more utilized
> that anyone can, or will ever see.

OK, thanks for this.

> Paul made a good point that applies to IPv6 deployment. It didn't
> matter that you had a week to study for the final exam. Other
> items were prioritized and the studying happens the night before.
> It is a fair assumption that there is at least one or two years
> of IPv4 space left in the IANA pool. Would it be remotely
> responsible for any company to drop everything to ensure IPv6 is
> already deployed, when Ipv4 space is still readily available? Now
> I'm not saying they wait until the last minute. I'm simply saying
> many companies will prioritize accordingly. Where your assumption
> is off, is that you think no one is, or wants to work on it. 

I wasn't suggesting no-one was working on it, just that I didn't see
any evidence that an IPv6-only service would be useful to many
customers for a very long time.  Recent messages from Alain Durand
indicate that the future Comcast 464 service is simply a centralised
NAT system to put multiple customer homes and offices on
single-layer NAT behind a single IPv4 address.  The service will
provide native IPv6 connectivity too, but I think it will be many
years before IPv6 itself is important to a significant number of

> Any company that wants to wait until the night before, will suffer
> the appropriate fate in the marketplace. But like the utilization
> of the IP address space, no one will never see what most
> companies are working on, or how they have prioritized IPv6
> deployment, until after the fact. In the end, the IPv4 space will
> become fully allocated, and IPv6 deployments will spread like a
> brushfire.

Yes, but I think there is much more scope for squeezing the IPv4
toothpaste tube than most other people think.  This is especially
the case if a map-encap system such as LISP, APT or Ivip was
implemented for IPv4.  I may be wrong, but it is an interesting

> Of course this should all be considered just another opinion.

It contains some useful *facts* too!

  - Robin

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