[arin-ppml] Policy Proposal: IPv4 Recovery Fund
bonomi at mail.r-bonomi.com
Sun Nov 23 21:33:56 EST 2008
> From owen at delong.com Sun Nov 23 19:08:03 2008
> Cc: arin-ppml at arin.net
> From: Owen DeLong <owen at delong.com>
> To: Robert Bonomi <bonomi at mail.r-bonomi.com>
> Subject: Re: [arin-ppml] Policy Proposal: IPv4 Recovery Fund
> Date: Sun, 23 Nov 2008 17:07:33 -0800
> > 2) The allocation methodology specified/required by the language at
> > the end of
> > the section named "Distribution of Recovered Space" has a major,
> > if not
> > fatal, flaw. To wit:
> > IF, for example, while nothing of a /21 or larger is available,
> > two ORGs
> > are each approved for a /21 on May 15, two more are approved (for
> > /21s) on June 1, AND an ORG is approved for a /20 on July 1,
> > THEN, when a /19 becomes available on July 15, under the 'best
> > prefix
> > match' rule, the "July 1" ORG would get a /20, and each "May 15"
> > ORG would get a /21, with the two "June 1" ORGs being left out.
> > I believe that the 'desirable' outcome in that situation is that
> > all 4 of
> > the /21 requesters should get space, and that the /20 requester
> > should have
> > to wait for the -next- free block.
> I actually thought about this, and, frankly, I think that the
> desirable outcome
> is that the /20 requester gets in front of the two /21s.
Desirable for whom? <grin>
It's obviously not desirable for the 3rd/4th requesters of the /21s,
who _have_ been waiting longer -- and thus, their 'need' _is_ more
acute than the party requesting the /20.
> The reason being that /21s are, by definition more likely to come up
> often. However, even in a situation where /20s or /19s are more
> the end result would be that the next /19 or /20 would most likely
> fill the
> two /21s needs. Since block fragmentation tends to be pretty much a
> one-way process, I think minimizing block fragmentation in this way
> is actually a desirable outcome.
This approach favors the large requester over the smaller one. Obviously,
those making larger requests will prefer this. ;)
I will point out that the "tighter" the return market is, the longer
people will have to wait for a block to become available. AND, the longer
they have to wait, the more likely it is that someone needing a 'slightly'
bigger allocation will show up into the queue. If the bigger requests
are always given preference, then the littler guy is going to get a chance
_only_ when something =exactly= his size comes along. If most of what does
come back is 'bigger' than his needs, this could be a _long_ wait. This is
*not* fair to the smaller requester.
I will also note that it is statistically proven that "best fit" match causes
_more_ fragmentation (over time) than "first fit". I don't have cites
to hand, but this was a routine part of late-1970s undergrad CS coursework
having to do with memory allocator schemes. 'Power of 2' block-sizing
greatly reduces, but does not completely eliminate the downside of best-
fit. I will concede that there are assumptions in that analysis concerning
repeated return, consolidation, and re-allocation -- assumptions that may
not be applicable to IP address-block allocations.
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