Where to buy Internet IP addresses

Stephen Sprunk stephen at sprunk.org
Tue May 5 15:43:20 CDT 2009

Jack Bates wrote:
> Mikael Abrahamsson wrote:
>> Why wouldn't DHCPv6-PD work within the home as well as between the 
>> ISP and the home?
> DHCPv6-PD requires manual configuration.

It doesn't need to; that's just a flaw in current implementations.

>> I see little reason why the main home gateway can't get a /56 from 
>> the ISP, and then hand out /62 (or whatever) to any routers within 
>> the home that asks for PD?
> Sure, but how does the router know it needs to hand out a /62? Then 
> what about the router after that? Does it hand out a /61? then the 
> router behind that?
> What if the ISP only gave a /60?

I think some folks are getting the model wrong.  Each router requests 
from its upstream router the delegation of a /64 for each downstream 
link and inserts the appropriate route when a response arrives.  If it 
receives a PD request on its downstream interface, it forwards it 
upstream; when the reply comes back, it inserts the appropriate route 
and forwards the reply to the requester.  Presto, a non-geek user can 
chain as many CPE devices as desired and they automagically configure 

(The ISP who's serving all these requests _could_ preallocate a /48 or 
/56 per customer, which might make aggregation in the PE router easier, 
or they could just have a gigantic pool per PE router and hand out as 
many /64s as required to each customer, which would [unnecessarily, 
IMHO] conserve address space.)

However, as interesting as this may be, it's not particularly useful to 
discuss how consumer ISPs _might_ do DHCPv6 PD when none of them have 
shown much interest in providing any IPv6 connectivity at all and many 
are blocking (through mandatory NAT) even 6to4.  And, until the eyeballs 
can speak IPv6, the content isn't going to speak it either...


Stephen Sprunk         "God does not play dice."  --Albert Einstein
CCIE #3723         "God is an inveterate gambler, and He throws the
K5SSS        dice at every possible opportunity." --Stephen Hawking

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