manipulating the best path, eBGP, MED?

Ondrej Zajicek santiago at
Tue Mar 7 19:08:10 CET 2017

On Tue, Mar 07, 2017 at 03:43:13PM +0100, Thomas at PhaseHosting wrote:
> Supp,
> thnqx for the reply,
> The BGP i have figured out and i have confirmation from my host they accept
> customer-set MEDs. Only i couldn't get these working and i found 2 posts on
> the internet with a different configuration and i don't know which one is
> the right one, "med metric 10;" or "default bgp_med 10;"
> Am i right that MED is the only option to influence the  eBGP and manipulate
> the prefered path? ( Values like AS are the same and others are not
> accepted)


I do not understand if you are trying to manipulate your hosts/routers (i.e.
outgoing direction) or neighbors routers (i.e. incoming direction).
Both could be influenced by bgp_med attribute (e.g. 'bgp_med = 100;' in
import or export filter) assuming your neighbors are from the same AS.

Option 'default bgp_med' is probably not what you want, that is used only if
a route with MED is compared to a route without MED.

Option 'med metric' could be used if you want to compare bgp_med
attributes on routes received from different AS numbers. But it is a
true/false option, the MED still must be set in filters.

Elen sila lumenn' omentielvo

Ondrej 'Santiago' Zajicek (email: santiago at
OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3,
"To err is human -- to blame it on a computer is even more so."

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