[arin-ppml] Rationale for /22
owen at delong.com
Tue Jul 28 17:39:15 EDT 2009
On Jul 28, 2009, at 10:46 AM, Kevin Kargel wrote:
>> AFAIK, there are no ISPs allowing customers to multihome with less
>> than a /24 currently but many who are allowing those /24s. So if
>> Org gets a /24 from ARIN or a /24 from it's ISP, there is the same 1
>> entry in the table.
> This is incorrect. If the Org gets a /24 from it's upstream ISP
> there is
> the same entry in the routing table. If the Org gets a
> discontiguous /24
> from ARIN there is an additional entry in the routing table.
> What it boils down to is whether or not the Org's ISP can aggregate
If an ORG multihomes with a /24 from their ISP, then, that /24 will
in the routing table either from the second transit provider, or, from
both transit providers, depending on configuration.
If an ORG multihomes with a /24 from ARIN, then, the /24 from ARIN will
appear in the routing table from both transit providers.
Otherwise, there is no difference to the routing table for a
> But if ARIN is handing out the /24's instead of the ISP isn't the
> far greater that the /24's will not be agregable? I doubt that ARIN
> will be
> able to only hand out /24's that would be.
The likelihood of the next /24 being aggregable is low regardless.
> I have no problem with extending the minimum mask length so long as
> it is
> tied hard to a requirement that anyone with a long mask have only one
> allocation, and to get another allocation the long mask netblock
> must either
> be aggregated in to the new allocation or returned.
So how about a policy like:
1. Amend current policy to extend mutihoming to /24 instead of /22 for
2. Add the following phrase to policy:
If an organization requesting additional space already possesses one
ARIN assignments less than /22, ARIN will, if possible make available
organization sufficient space to aggregate existing smaller blocks
into the new
space in addition to the justified additional space and shall allow a
of no less than 18 nor more than 36 months before reclaiming the
assigned smaller blocks. If ARIN does not have a sufficiently large
shall issue space in such a way as to alllow maximal aggregation
and the return of as many addresses as possible after renumbering.
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