Service Providers behaviour for dual homed enterprises

Thu Sep 24 13:47:24 UTC 2015

On 24/Sep/15 15:21, William Herrin wrote:
> Hi Jason,
>
> That's normal. Verizon does it too. Both have "community" tags which
> you can attach to your route advertisement. Each will have one that
> indicates they should give external routes the same "local pref" as
> the route you announce to them. Tagging your route announcement with
> the proper community will cause them to route based on AS path length
> as you expect.

Depending on the provider, this can't always be guaranteed, i.e., that
the available LOCAL_PREF values a customer can trigger via a BGP
community support anything <= what routes the network considers "external".

What's possible (or available) may also be influenced by whether one's
upstream is "transit-free" or not, I imagine.

Mark.