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Using IPv6 with prefixes shorter than a /64 on a LAN

On 2/4/2011 6:45 PM, Mark Andrews wrote:
> I used to work for CSIRO.  Their /16's which were got back in the
> late 80's will now be /48's.

That's why I didn't try doing any adjustments of X is the new /32. The 
whole paradigm changes. Many ISPs devote large amounts of space to 
single corporate network sites. Those sites will now have a single /48. 
On the other hand, we currently give /32 to residential customers. They 
also are getting a /48.

Which is why the only way to consider address usage from an ISP and RIR 
perspective is by how it is handed to a standard ISP of a given size. 
Originally, ARIN was being overly restrictive and it was "/32 for every 
ISP". They have loosened up, and will continue to do so (including ISP 
to ISP) as future proposals come to fruition. So from an ISP 
perspective, you have to consider your total IPv6 allocation size 
(within the first 32 bits of IPv6) in comparison to your total IPv4 
allocations summed.

 From what I can tell, on average, all ISPs are shifting between 8 and 
16 bits to the right from their total IPv4 size depending on their 
primary customer type (residential ISPs shift less than ISPs that 
primarily only service corporations).