[arin-ppml] IPv4 Fragment Managemnt policy proposal

Owen DeLong owen at delong.com
Thu Apr 29 10:55:33 EDT 2010

On Apr 29, 2010, at 12:59 AM, <michael.dillon at bt.com> wrote:

>> Each time ARIN approves an IPv4 request which it cannot 
>> satisfy from 4 or fewer bit-aligned blocks of free address 
>> space, ARIN shall notify the requestor that there is 
>> insufficient free address space to meet their request and 
>> shall offer the requestor their choice of the following
>> alternatives:
>> a. They can have the largest 4 available bit-aligned blocks 
>> of free addresses.
>> b. This section reserved -- (in case we implement the waiting 
>> list for unmet requests policy)
>> c. They can seek resources through the directed transfer 
>> policy in section 8.3 of the NRPM.
> Seems like a good idea. 
> One thing to be aware of is that ARIN does not allocate CIDR
> blocks. They allocate IP address ranges, i.e. from a start
> address to an ending address. One time we received an allocation
> that consisted of two disjoint ranges. One of those was 3/4
> of a reserved block where we had already received 1/4 of the
> block previously. And the other was 1/4 of a new reserved block.
While that is true, it does not need to remain true.  ARIN allocates
IP resources according to policy.  If policy states that ARIN will
allocate bit-aligned prefixes, then, ARIN will begin allocating in
that manner.

> It might be a good idea to think this through and see whether
> or not it can be simplified to say that ARIN will never allocate
> more than 4 blocks to satisfy a request, and leave off the bit
> about when there is insufficient free space.

Having thought that through, I believe it would complicate the
policy and reduce clarity. Brevity is not always simplicity.


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