[ppml] IPv6 Assignment Guidelines, Straw Man #2

Leo Bicknell bicknell at ufp.org
Mon Aug 20 12:00:46 EDT 2007

In a message written on Mon, Aug 20, 2007 at 04:36:36PM +0100, michael.dillon at bt.com wrote:
> I object to this use of the HD Ratio. Unless ARIN policy is changed to
> require all ISPs to regularly report their IPv6 utilization and current
> HD ratio, then I think ARIN should not require ISPs to "meet" an HD
> Ratio. Many ISPs will be getting an IPv6 allocation with the expectation
> that they will never come back for another allocation, or at least not
> for many years. In that time, the HD Ratio requirement could well be
> removed or changed. It is a burden to require ISPs to track that HD
> Ratio. If ARIN wishes to impose the burden it must be done openly and
> explicitly, not tacked on to another policy change.

I'm not sure I understand your complaint at all.

LIR's are already required to "meet" an HD Ratio of 0.94, from
section 6.5.2: http://www.arin.net/policy/nrpm.html#six52

It clearly states that if you come back for more space, your existing
space must be used to at least an HD Ratio of 0.94.

Now, consider you're a LIR, and you have an end site that actually
needs more than 65536 subnets.  Under the current policy (,
http://www.arin.net/policy/nrpm.html#six542), here's the policy:

] When a single end site requires an additional /48 address block, it must
] request the assignment with documentation or materials that justify the
] request. Requests for multiple or additional /48s will be processed and
] reviewed (i.e., evaluation of justification) at the RIR/NIR level.

There is no objective criteria.  Does needing 65537 subnets get you
a second /48 (or /47)?  Can you get a /47 to have room for growth
when you've used 65500?

This change would make it so that if the first /48 is utilized to
an HD Ratio of 0.94, then a second /48 (or /47 in total) could be

When would an ISP report this information to ARIN?  Only when they
come back and ask for more space.  When would they have to track
HD Ratio for a downstream customer, ONLY if the customer received
more than a /48 for a single site.

Could it change?  Sure.  The same problem exists in IPv4, but of
course much worse as you have to track every customer, not just the
very large ones (http://www.arin.net/policy/nrpm.html#four2341, 80%
rule).  Surely you're not trying to say that since these rules may
change in the future there should be no rules, no guidence for
existing ISP's?

       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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