Return Traffic path when doing Policy Based Routing (Route maps)

Unanswered Question
Sep 20th, 2007


Consider a case where by Voice traffic uses one link and data traffic uses a different link when route maps have been configured on a spoke router.


Will the voice traffic use the same path it used when leaving the spoke router or the headend router will use any path (optimal) for the return traffic to the spoke?



I have this problem too.
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Richard Burts Thu, 09/20/2007 - 08:41


If you have successfully configured Policy Based Routing on the spoke router to send voice traffic from a spoke router over a particular link to the head end router, then it will have no effect on traffic from the head end router coming back to the spoke. If you want the voice traffic from the head end router to use a particular path then you will need to configure Policy Based Routing on the head end router.



edwardwaithaka Thu, 09/20/2007 - 09:07

What would be the effect in the following scenario;

- I dont configure PBR on the hub router hence the router load balances

- On the Spoke router, I configure CBAC (Context Based Access Control) IOS Firewall on the interfaces facing the Hub.

Would the IOS Firewall drop some of the traffic due to statefull firewalling?

Have a look at Figure 3 in this doc;

Richard Burts Thu, 09/20/2007 - 09:55


I have looked at both links. I do not see how figure 3 in the second link relates to your question. But I believe that figure 17 in the first one does address your question. It mentions an example in which there are two outbound interfaces and discusses the possibility that CBAC can be enabled on both outbound interfaces. In the case where you enabled it on both interfaces I believe that all voice traffic would pass through CBAC. If CBAC were configured on just one interface then I believe that it would lead to dropping some packets.




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