[arin-ppml] Rationale for /22

William Herrin bill at herrin.us
Fri Jul 31 10:17:59 EDT 2009

On Thu, Jul 30, 2009 at 11:30 PM, Leo Bicknell<bicknell at ufp.org> wrote:
> If a network multihomes with a subnet of a PA block and someone
> somewhere else in the routing table filters that route but not the
> PA block, there is still full reachability.  If someone multihomes
> with a PI block and that same person filters the same route, there
> is no reachability.
> Thus the size of the set of all routes is the same; but the size
> of the filtered routes but still global reachability set is reduced.
> *There are a number of people trying to use the second set.*


I'll ask you the same question I asked Jon: Who?

People vote with their feet. In 2009, those feet have voted as
unanimously as we can detect against filtering on the RIR minimums
without also employing a default route to a transit provider that

Seriously, if you know of an ISP that's filtering on RIR minimums and
relying on announced covering routes (with no default route) to catch
the missing routes, I'd like to know who so I can go win an argument
with one of my transit providers about which space to assign me.

> While the most traveled road is Multihome with PA, then Multihome
> with PI, there are plenty of folks who single home with PA (no
> global routing table slot) until they can qualify for an ARIN PI
> block, then they multi-home.

I've encountered something like this exactly twice. In both cases they
were multiply single-homed with a malfunctioning network. I was
brought in to clean up my predecessor's mess.

That the /22 policy encourages folks to screw up their networks is
hardly a point in its favor.

> I suspect many of the folks on this list would spend a lot more
> effort trying to multi-home if they could get 1 /32 from ARIN for
> $10 per year.  The number of cable modem and DSL customers asking
> their providers for BGP would skyrocket.  It's not because those
> folks are multi-homed with PA space today.

Straw man. We're talking about /24's not /32's. And $10 per year
doesn't buy you BGP with any ISP I've ever talked to. Further, with
the right language in a /24 policy we can, if we want to, make sure it
never does.

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

More information about the ARIN-PPML mailing list