Re: what problem is solved by proscribing non-64 bit prefixes?

[Brian E Carpenter <brian.e.carpenter at gmail.com>]

On 2008-10-01 23:35, michael.dillon at bt.com wrote:
>> In a typical IPv6 ADSL household landscape...
>>
>> An ADSL IPv6 operational deployment offers a /64 prefix at 
>> home.  With that, I can't subnet _and_ use IPv6 stateless 
>> auto-configuration.
> 
> In a typical IPv6 ADSL household landscape the ISP will assign
> you a /48 with plenty of subnetting space. In some regions
> there will be some ISPs who will only assign a /56 to residential
> sites, but that still gives you a reasonable amount of subnetting
> ability. Under RIR rules, an ISP can justify giving you a /48
> if you ask them for it.

Yes. We shouldn't forget that there are, objectively, 15 trillion
/48s available, so whatever religious faith people may have
in the HD ratio, there *are* plenty of /48s. The value of the
HD ratio (and the RIR practices related to it) is to avoid
wasteful use of the bits *before* the /48 boundary.

   Brian
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