Cisco: BGP path selection for inbound traffic

In some previous post we saw how we can manipulate BGP paths using attributes for outgoing traffic. Today we will see how to use another BGP attribute, but this time for manipulating inbound traffic. First I would like to ask you to have a look into the topology file and also to check the config files (if you have a basic idea about how BGP is configured that you don’t need the config files).

From the table above:
we see that the attributes needed for inbound traffic manipulation are AS-Path and MED. Today we will use AS-Path for traffic manipulation (MED sometime in closer future).

Beside using BGP attributes, there are other ways to manipulate traffic and paths in a BGP environment, but usually this need that the provider will support your actions. As an example to understand, you can do route tagging in your network (for example in MPLS on your CE) and your ISP will apply rules based on different tags (on PE side), but this is out of the scope of this tutorial and will be discussed maybe in another tutorial.

For our test environment, that you see in the topology, we advertise everything into BGP domain, exactly as draw, so there will be no problems of reachability.

Please see the tutorial and explanations below:

Published by

Calin

Calin is a network engineer, with more than 8 years of experience in designing, installing, troubleshooting, and maintaining large enterprise WAN and LAN networks. Currently he's Cisco (CCNA, CCNP, CCIP) and Linux (LPIC) certified and working to obtain CCIE certification.

3 thoughts on “Cisco: BGP path selection for inbound traffic”

  1. This post together with the one for outgoing traffic path selection are very good to follow in the real networks. In general I like your blog, pretty nice and useful tutorials. Please write me at [email protected] in case that you want me to contribute with some ideas for new articles.
    Keep on the good work!

  2. Thanks for your comment BrownLeaf. I’m glad that you find this blog useful and be sure that I’ll write to you in case that I need some ideas, but for now the only thing that it’s missing is time to put here everything that I want!

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