[c-nsp] Suppressing/Over-riding Longer Prefixes

[Roland Dobbins]

On 31 Dec 2014, at 7:47, f287cd76 at opayq.com wrote:

> Much of this is random, and for the most part isn't an issue other 
> than the asymmetric routing.

Asymmetric routing is how the Internet works.

> But there are some business partner AS's I'd like to over-ride and 
> force their traffic to use the local ISP as much as possible.    No 
> point backhauling it to my other site.

With regards to inbound traffic (from your perspective), you can control 
what you advertise and how.  Many ISPs allow you to tag routes with 
communities/attributes which can influence route propagation.  That 
being said, those are the only mechanisms you have; you can't control 
route selection on remote networks beyond the the parameters of your 
route advertisements.

> Looking for suggestions on how to influence routing to do this.

For outbound traffic (from your perspective), you can do this with 
prefix-lists.

Here's an example (scroll down to the bottom of the page):

<http://www.networkgalaxy.org/2013/07/filtering-routes-in-bgp-using-route.html>

-----------------------------------
Roland Dobbins <rdobbins at arbor.net>