Doug Barton dougb at
Mon Dec 2 23:02:07 UTC 2013

On 12/02/2013 02:35 PM, Ricky Beam wrote:
> We don't know what we'll need in the future. We only know what we need
> right now. Using the current dynamic mechanisms we can provide for now
> and "later", as "later" becomes apparent.

I hate to keep repeating this, but each time the argument comes up the 2 
camps split into their factions and ignore my suggestion, so here goes. :)

I have been proposing for years now that ISPs reserve a /48 per customer 
end site, which aligns with both the protocol design and the policies of 
most if not all RIRs. Then as rollout actually occurs make the first /56 
(1/2 way between /48 and /64) available to the customer (in whatever 
form 'make available' occurs, such as DHCPv6-PD). That way you have 
protected your customer from having to renumber in the future should 
they need the full /48. Then down the road IF you run out of space, and 
IF you can't get more, you can then go back and start assigning the 
second /56 out of the /48s you had previously reserved.

Of course this same logic could be applied to /60s instead of /56s, but 
even I (sympathetic to the argument of not repeating the wasteful 
mistakes of the past as I am) think that's too small.



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