BGP multihoming with two address spaces

William Herrin bill at
Wed Jan 29 18:44:53 UTC 2014

On Wed, Jan 29, 2014 at 6:32 AM, Joseph Jenkins
<joe at> wrote:
> I am seeking some feedback/help with my BGP configuration.
> I am peering with two providers level3 and tw.  Unfortunately all of
> my address spaces are preferring the route over tw rather than level3.

Hi Joe,

I had a situation like this a couple months ago but my two providers
were: Centurylink and Centurylink. No matter how many prepends I
added, the traffic preferred the slow link in one state to the fast
link in another.

It turned out that Centurylink (Embarq) gets to the Internet via
Centurylink (Qwest). Unless modified by communities, Qwest has a local
pref that delivers traffic to direct customers in preference to other
ASes. And the folks in Embarq's support had no idea what Qwest was

This sort of local-pref default seems to be a common practice with
backbones. It's very annoying. I wish they'd stop.

Bill Herrin

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

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