[arin-ppml] Rationale for /22

Michael K. Smith mksmith at adhost.com
Thu Jul 30 20:10:26 EDT 2009

On 7/30/09 4:05 PM, "Owen DeLong" <owen at delong.com> wrote:

> On Jul 30, 2009, at 3:46 PM, Leo Bicknell wrote:
>> In a message written on Thu, Jul 30, 2009 at 05:48:06PM -0400, William Herrin
>> wrote:
>>> If I may draw it back to the question I started with: Can you offer a
>>> well grounded reason to believe that changing the minimum allocation
>>> size for *multihomed* systems is likely to affect the size of the
>>> global table?
>> I believe it is reasonable to assume each decrease in prefix size
>> allows more orgs to qualify, and thus increases the routing table.
>> Now it may be we only add 1000 orgs, of which 800 previously were
>> multi-homing with cutouts, so the net is 200 routes, but that doesn't
>> mean it's not a decrease.
> I don't get this...
> Under current policy, any org that multihomes qualifies for a /24 from their
> upstream.
> Given that, any org that multihomes already qualifies to put a route in the
> DFZ.
> What increase are you concerned about that is added by moving the ARIN
> boundary from /22 to /24?
> Today, they can save $100/year and get space from an upstream that
> they don't pay ARIN for, as well as getting a  /24 even if they want to
> multihome a single host.  That's CURRENT ARIN policy.
> If we move the boundary to /24, then, in addition to that option, networks
> that have ~128 - ~400 hosts would gain the option of applying to ARIN
> and getting a /24 or /23 to multihome with that was independent of
> both of their providers.
> Why would someone who is not willing to multihome for $100 less
> pay $100 more to multihome _AND_ jump through more hoops just
> because we changed the ARIN boundary?
> Owen
Are you saying you think that a small provider with a upstream-provided /24
wouldn't want to jump through the hoops to be provider independent?  In the
past, I've been in just this type of position, advertising multiple /24's
assigned from upstreams until I could justify a /20 from ARIN.  If I had the
opportunity to number out of a /24 instead of waiting until I had a /22 I
would have jumped at the chance.

What was the rationale for the /20 in the first place?  Was it more than an
arbitrary number?  I can't see any detraction from getting providers to get
an ARIN-assigned /24 instead of having to get a /24 from one provider and
route it out another, being historically on the "purchasing" side of that
arrangement.  The only downside I can see is providers that think having a
customer with their assigned space somehow binds them together, fiscally



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