valley free routing?

William Herrin bill at
Wed Mar 5 21:08:21 UTC 2014

On Wed, Mar 5, 2014 at 4:00 PM,  <Valdis.Kletnieks at> wrote:
> On Wed, 05 Mar 2014 15:23:55 -0500, William Herrin said:
>> Can anyone tell me about a situation in which a route which was not
>> valley free was not a result of a misconfiguration or a bad actor? For
>> those who don't recall the terminology, a network path is valley free
>> if it crosses exactly zero or one free peering links when traveling
>> between the two endpoints.
> Assume 3 providers A B and C, where you have a single-homed customer on A and a
> single-homed customer on C, and A and C don't peer.  Traffic may end up going
> thorugh an A-B peering and a B-C peering. And whether A-B and B-C are a free
> peering or a paid transit is a business deal, outside the scope of BGP, unless
> you want to abuse communities...
> Are A and/or C "bad actors" for not peering? Jury is still out on that one.

Hi Valdis,

It's that business deal I want to hear about. When A-B and B-C are
free peering but the traffic goes A-B-C for some reason other than a
misconfiguration or deliberate abuse. On or off list, I'd like to know
about real-life use cases where folks do this on purpose.

Bill Herrin

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

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