Network designers and implementers try to avoid policy routing, as its common implementation in Cisco IOS requires a complex mix of access-lists and route-maps that have to be deployed on a hop-by-hop basis. In most cases, distance vector routing protocols can be used to implement policy routing requirements in large networks. The article describes how you can use BGP to implement an architecture where a set of applications should prefer a different subset of links than other applications.
Summary
Most network designers and implementers try to avoid policy routing, as its common implementation in Cisco IOS requires a complex mix of access-lists and route-maps that have to be deployed on a hop-by-hop basis. In reality, distance vector routing protocols can be used to implement common policy routing requirements in enterprise networks where a set of applications should prefer a different subset of links than other applications.
Routing protocol-based policy routing should be implemented (if at all possible) with BGP, as it gives you the richest set of tools to use to influence the route selection policy. EIGRP is a viable alternative (you can manipulate the delay portion of the metric for each individual IP prefix), with RIP being the solution of last resort. You cannot implement the same mechanisms with any link-state protocol, as you cannot increase the link cost for individual IP prefixes (OSPF with type-of-service support would allow you to do that, but it’s never been implemented in a mainstream routing device).
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