using "reserved" IPv6 space

Owen DeLong owen at
Tue Jul 17 04:28:18 UTC 2012

On Jul 16, 2012, at 7:35 PM, Karl Auer wrote:

> On Mon, 2012-07-16 at 22:04 -0400, Lee wrote:
>> Each site gets a /48.  Even the ones with less than 200 people.
>> [...]
>> Which is *boring*.  Nothing novel, no breaking out of "IPv4 think"
>> aside from massively wasting address space.
> It's only a waste if you get nothing for it. By using /64 everywhere you
> get a more homogeneous network, easier to administer, manage, document,
> maintain... There are similar advantages, writ larger, to using /48 for
> every site.

It's also a waste if you don't ever use the address and the protocol gets deprecated
before a significant percentage of the addresses are allocated.

Earlier in this thread, I did the math showing how it will likely, even with very liberal
allocation policies, be 100 years or more before we allocate 1/40th of the total
IPv6 space to RIRs.

> Whether you have 2, 20, 200, 2000 or 20,000 hosts in a /64 subnet, you
> have still only used 0% of it, to a dozen or more decimal places.
> IPv4-think says that's a waste. IPv6-think says "great - all my subnets
> are large enough". Resizing IPv4 subnets is common; resizing IPv6
> subnets will be rare.
> IPv4-think is conserving addresses. IPv6-think is conserving subnets. We
> don't buy dining chairs based on the number of atoms in them - we buy
> enough to seat the people who need seating.


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