Scalable Policy Routing

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By Ivan Pepelnjak

Common implementation of policy routing in Cisco IOS is performed within a single device and requires a complex configuration mix of access-lists and route-maps. In a larger network where you have to influence the end-to-end packet flow, the hop-by-hop method of the IOS policy routing clearly does not scale.

If you need professional help in designing or deploying solutions described in this article, contact the author or NIL's Professional Services team

Routing protocol-based policy routing

Server virtualization has allowed us to dedicate virtual servers (and, consequently, specific IP addresses) to individual applications, and distance-vector routing protocols (or MPLS Traffic Engineering) help you provision alternate paths for specific IP prefixes. You could influence route selection for individual prefixes with EIGRP (using the per-interface or per-neighbor offset-list), but it’s much better if you could deploy BGP due to its support for a rich set of path attributes.

Sample policy routing with BGP

Read more in the Scalable Policy Routing IP Corner article

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