[arin-ppml] Rationale for /22

William Herrin bill at herrin.us
Tue Jul 28 11:29:35 EDT 2009

On Tue, Jul 28, 2009 at 10:32 AM, Joel Jaeggli<joelja at bogus.com> wrote:
> William Herrin wrote:
>> Given the shortage of IPv4 addresses, why structure the policies so
>> that we give anyone more than they actually want?
> The minimum number of addresses that can be used may not in fact reflect
> the minimum that should be used.
>        For the purposes of minimizing fragmention.
>        Supporting basic network operation (it's nice when traceroute
>        and pmtud work) because your intermediate routers are privately
>        numbered.
>        Limiting the consequences of imagination failure, which may
>        sound flippant but renumbering, requesting an additional block,
>        or and point one and two are good reasons to make a potential
>        multi-homer justify the assignment of a block of the appropriate
>        size for that activity.

Hi Joel,

I could almost see that argument on the ISP side but it doesn't make
sense to me on the end-user side, particularly when they may be
trivially multihomed. I surely wouldn't want to presume that I know
every registrant's address count needs better than he does though. f
you don't mind, let's just focus on the downside risk.

So, the registrant asks for a /24 and a year later his replacement who
is a better network engineer figures out he really needs a /22 after
all. What's the impact? Other than insisting on giving him a /22 up
front, is there another way to mitigate that impact?

Bill Herrin

William D. Herrin ................ herrin at dirtside.com  bill at herrin.us
3005 Crane Dr. ...................... Web: <http://bill.herrin.us/>
Falls Church, VA 22042-3004

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