[ppml] alternative realities (was PIv6 for legacy holders (/wRSA + efficient use))

William Herrin arin-contact at dirtside.com
Thu Aug 2 13:01:13 EDT 2007

On 8/2/07, Peter Eisch <peter at boku.net> wrote:
> Multi-homing in that reality becomes hit and miss.  It's not worth paying
> any fees to the second ISP if anyone who wants to reach you is sitting
> behind a filtering ISP.  The funny part is that they lose you as a customer
> based on policy enacted by a non-related entity.


That's only true if a sufficiently high percentage of the ASes filter
the route. If only a few ISPs filter the route then their customers
suffer at least as much as you do. That can be a real problem for the
filtering ISP if you have interesting content and the ISP's business
model happens to be predicated on hyper-optimized routing with a
strong SLA.

Prefix filtering by a network operator weakens his ability to reach
others on the Internet at the same time that it weakens yours. In
fact, it weakens him more than you: your access is only obstucted to
one entity. His is obstructed to many. That's a weakness his
competitors can exploit.

Now you know why most of us stopped filtering to prefixes shorter than
/24 the last time we tried it.

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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