[AusNOG] steering inbound BGP (Telstra)

[Ben]

On Sun, Feb 16, 2014 at 08:12:15PM -0800, Matthew Moyle-Croft wrote:
> 
> On 16 Feb 2014, at 8:09 pm, Joshua D'Alton <joshua at railgun.com.au> wrote:
> 
> > Whoops completely forgot about localpref!
> > 
> > @Andrew  2x24/s wouldn't work for Telstra inbound though as they'd still be preferring their learned /23 from their customer vs the 2x/24s from their peer(s), right? Or do you mean it would work for making the majority of the traffic come in via the other provider?
> 
> Yes it would - /24s are more specific so preferred.  /23 would only kick in if /24s stopped being advertised.

Although that may work, I wouldn't advocate it without fallback routes.

What happens if Telstra receive traffic internationally from a peer on your advertised / 23?

It comes into their network, and they have to do something with it.  Either they have a limited
set of routes of their customer routes in that network, or they have a full BGP table.

In the first instance - they'd still route directly via the /23, in the second instance they would
then send traffic to you via domestic transit via another provider from international source.

In the first instance it doesn't fix your problem, and in the second instance it could be considered
against reasonable network usage.

Ben.