[menog] IPv4 March 2011 depletion

Brian Candler B.Candler at pobox.com
Mon Nov 15 12:36:07 GMT 2010

On Mon, Nov 15, 2010 at 03:30:00AM -0800, Owen DeLong wrote:
> If you are talking about doing this on a per customer basis, it
> is absurd.
> If you have NAT44+IPv6, you don't need NAT64.

Yes you do, if there are any IPv6-only devices in the customer's network.

Presumably you *do* want to see people starting to deploy IPv6-only devices
in their network, rather than running dual-stack forever?  Because, for as
long as you admit that some sort of IPv4 is necessary in the customer's LAN,
you give people a strong disincentive against deploying V6 in the first

> If you have IPv6 with NAT64, you don't need RFC-1918 or NAT44.

Yes you do, if there are any IPV4-only devices in the customer's network.

We don't have the luxury of redesigning every customer's network from
scratch, nor of telling them what devices they may add or not add to their

> > 2. new V6-only users, which is where you want the growth to be
> Eventually, growth will be forced in this direction.

I am old enough to remember when people connected to two networks:

(1) X25 and The Internet
(2) CLNP and The Internet

Today we have:
(3) IPV6 and The Internet

You don't need me to tell you what happened in cases (1) and (2), despite
strong government and management pressures to "force" people in a particular

Compared to what people have and are using today, V6 gives exactly *zero*
benefit to the vast majority of users.  Cost without benefit = no business

AFAICS, the types of "forcing" required would be:
a. ISPs cease to offer V4 services at all (not even NAT44)
b. ISPs increase their charges to V4 users, or offer discounts to V6-only

Maybe there is some mileage in (b). However ISPs work on such small margins
and in such a competitive market that it may be very hard in practice.

> Equipment which does not know about IPv6
> should safely ignore it like any other unknown protocol.

I don't think "should" and hope is good enough. Any across-the-board change
to the service you provide has potential impact, and there are hundreds of
different types of no-name routers with buggy firmware, partial or untested
V6 implementations.  If and when those calls hit the callcentre, it would be
wise to be able to offer a quick solution to the affected customers, rather
than "sorry, your equipment doesn't work with our service, please buy a new
one or go somewhere else"

This will of course vary between markets. It won't be as much of a problem
where the ISP owns and manages the CPE - although the user may still be
affected if you turn on V6 on the LAN side, it's relatively easy to turn it
back off again.



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