[arin-ppml] Rationale for /22

Ted Mittelstaedt tedm at ipinc.net
Tue Jul 28 14:25:19 EDT 2009

Kevin Kargel wrote:
> Ted,
>> If you set the minimum size of a table entry to /25 instead of /24 then
>> you have now doubled the possible table entries.  It doesn't matter if
>> the entries are gratuitous or not, the way subnet mathematics works, for
>> every drop in the bit boundary, from /25 to /26 to /27 and so on, you
>> double, quadruple, etc. the total possible route entries.
>> With the increase in router ram and router CPU speed over the years,
>> some decrease in the minimum is warranted.  If we didn't have IPv6
>> coming up - which will also double the number of advertisements once
>> everyone runs dual-stack - we could support an even further decrease
>> in the minimum.  But we can't yet support multiplying the number of
>> potential routing slots by 200 on the Internet.
>> Ted
> So are you saying then that we need to limit the number of organizations
> that have IP allocations to manage the number of slots?  

This is a fallacious argument.  You are implying that limiting the 
number of ARIN-supplied IP allocations will limit the number of routing
slots.  In actual fact, an org can use up a routing slot by advertising
LIR-provided IP assignments.

I don't deny we should limit the number of slots but this is only
loosely related to the number of orgs that have IP allocations.

RIR policy has been to discourage growth of routing slots, but the
RIR cannot prevent this from happening.  Even if the RIR stops handing
out AS numbers, an org with an existing subnet can break it into
multiple advertisements if they choose which also increases slots.


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