[ppml] Policy Proposal: IPv6 Assignment Guidelines

Leo Bicknell bicknell at ufp.org
Thu Aug 23 10:03:46 EDT 2007

In a message written on Thu, Aug 23, 2007 at 03:08:51PM +0200, Iljitsch van Beijnum wrote:
> On 23-aug-2007, at 3:44, Leo Bicknell wrote:
> >Would you support my "Straw Man #2", reproduced here for your
> >convenience?
> >] LIR's may assign up to a /48 to an End Site.  End Sites requiring
> >] more address space than a /48 may be assigned a larger block  
> >provided
> >] the utilization inside that block meets an HD Ratio of 0.94.
> I'm not sure how that works. Do I need to use 33000 subnets in a /48  
> (that's about a HD ratio of 0.94) before I can get a /47? Or do I  
> need to submit a plan for 456000 subnets to get a /44? But 456000  
> subnets will also fit in a /45, so why the extra bit?

HD Ratio is defined in section 6.2.8:

I've created a little table, I presume ARIN would make such a table
available on the web site for easy reference.

In A	In Use	Out of	To Get
/48	33,689	65,536	/47
/47	64,634	131,072	/46
/46	124,002	252,144	/45

I could go on, but we're now talking about a single site, getting
PA space from a provider with over 100,000 subnets.  That seems,
unlikely.  However, should it occur, the foruma works.

Also, why the extra bit, we've decided with HD Ratio that as you
get larger you should have some extra bits here and there to allow
you to allocate efficiently internally, so it's more likely you'll
fit in a single block.  If you're worried about that, this is not
the place to worry.  Going from a /45 to a /44, inside of a PA block
that's nicely aggregated is not such a big deal.  Going from a /32
to a /19 due to the effects of HD ratio on larger providers is
probably a better place to start.

       Leo Bicknell - bicknell at ufp.org - CCIE 3440
        PGP keys at http://www.ufp.org/~bicknell/
Read TMBG List - tmbg-list-request at tmbg.org, www.tmbg.org
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