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:

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

  • December 16, 2008 at 18:18
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    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!

    Reply
  • December 17, 2008 at 11:26
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    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!

    Reply

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