Dual stack IPv6 for IPv4 depletion

Wed Jul 15 21:34:13 UTC 2015

> On Jul 15, 2015, at 13:55 , Barry Shein <bzs at world.std.com> wrote:
> 
> 
> On July 15, 2015 at 09:20 owen at delong.com (Owen DeLong) wrote:
>> 
>> There are two ways to waste addresses. One is to allocate them to users who
>> don,Ab€™t actually use all of them.
>> 
>> The other is to keep them on the shelf in the free pool until well past the useful
>> life of the protocol.
> 
> I'd add a third which is segmentation and I think that's a real
> threat. That is, assigning large chunks to specific functions by
> policy usually in support of technical needs. For example IPv4's
> multicast block. Poof, 224/4 gone. Or similar.
> 
> Suddenly it's not 2^N bits it's just N bits.
> 
> My claim is that such segmentation tends to grow over time as people
> find good arguments to segment.
> 

fd00::/8 is already wasted on ULA.
fe80::/10 (effectively fe00::/8) is already allocated (somewhat wastefully, as a /64 probably would do the trick) to link local
ff00::/8 is already allocated to multicast.

That covers multicast and RFC-1918. Are there any other IPv4 segmentations that you can think of?

I’m not being snarky… I’m genuinely interested.

Given that we came up with 3 total segmentations in IPv4 over the course of 30 years of IPv4 protocol use,
which consumed a total of /4(multicast)+/8+/12+/16(RFC-1918)+/16(link local) of IPv4 and 3 /8s of IPv6.

Even if we toss 5 more /8s to segmentation over the next 30 years, I think we’re OK, though we would have
burned through a /5 at that point in segmentation.

I think effectively, we can consider that e000::/3 is essentially set aside for such purposes and we still have
5/8ths of the address space after burning through the current /3 of unicast and a second /3 of unicast while
we contemplate a more restrictive policy.

Owen

> -- 
>        -Barry Shein
> 
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