[arin-ppml] IPv6 Non-connected networks

William Herrin bill at herrin.us
Thu Feb 4 17:37:41 EST 2010

On Thu, Feb 4, 2010 at 4:14 PM, Barbara Roseman
<barbara.roseman at icann.org> wrote:
> I think there's a subtle but important distinction
> that's being lost, and that Cathy and Marla tried to clarify.

Hi Barbara,

If I understood the distinction that Cathy and Marla drew, the point
they're making is that nowhere does ARIN say what routes an ISP has to
carry. ARIN doesn't even say what routes an ISP ought to carry. Nor is
there any other legal obligation which compels ISPs to carry any
particular routes for addresses ARIN allocates. Like Verizon has done
with IPv6 /48's, ISPs are welcome to disregard any routes they don't
like for any reason at all. That they rarely exercise that choice
means nothing more sinister than that routing the address ARIN
allocates is good for business.

Do you feel that's a reasonable re-statement of what they said? I'd
hate to be obtuse about it, so if I'm missing the their point please
help me understand.

I think I understand the claim, but I dispute it.

Cause and effect is no less potent for being indirect. The
practicality of altering BGP routing activity based on a second feed
of assignments matched to assignment classes is doubtful. Even if it
could be done from a technical perspective, ARIN doesn't publish the
criteria by which each registrant qualified for their addresses, so
such a feed has no source for its content.

Realistically, functionally, technically, the tools I as an operator
have for implementing routing policy can only paint with a broad
brush. Discard small announcements in this /8. Depreference that one.
Unless ARIN classifies registrants in a manner consistent with those
tools, my choices for routing policy devolve to two basic options:
accept routes announcing ARIN IP addresses or don't.

In other words, ARIN sets the routing policy for North America. Not
explicitly, cleanly and openly, but haphazardly, indirectly and

The unspoken and unintentional yet cumulative net effect of ARIN's
allocation practices make ISPs a mob-style offer they can't refuse:
carry all of the addresses we approve or carry none of them and lose
your business.

At this point we're stuck with that for IPv4. The addresses are
already deployed. With some mild adjustments to our allocation
practices, we don't have to be stuck with that effect for IPv6.

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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