Cisco Systems 3560 Manual De Usuario

You can use policy-based routing (PBR) to configure a defined policy for traffic flows. By using PBR, 
you can have more control over routing by reducing the reliance on routes derived from routing 
protocols. PBR can specify and implement routing policies that allow or deny paths based on:

Identity of a particular end system

Application

Protocol

You can use PBR to provide equal-access and source-sensitive routing, routing based on interactive 
versus batch traffic, or routing based on dedicated links. For example, you could transfer stock records 
to a corporate office on a high-bandwidth, high-cost link for a short time while transmitting routine 
application data such as e-mail over a low-bandwidth, low-cost link.

With PBR, you classify traffic using access control lists (ACLs) and then make traffic go through a 
different path. PBR is applied to incoming packets. All packets received on an interface with PBR 
enabled are passed through route maps. Based on the criteria defined in the route maps, packets are 
forwarded (routed) to the appropriate next hop. 

If packets do not match any route map statements, all set clauses are applied.

If a statement is marked as permit and the packets do not match any route-map statements, the 
packets are sent through the normal forwarding channels, and destination-based routing is 
performed. 

For PBR, route-map statements marked as deny are not supported.

For more information about configuring route maps, see the 

.

You can use standard IP ACLs to specify match criteria for a source address or extended IP ACLs to 
specify match criteria based on an application, a protocol type, or an end station. The process proceeds 
through the route map until a match is found. If no match is found, normal destination-based routing 
occurs. There is an implicit deny at the end of the list of match statements.

If match clauses are satisfied, you can use a set clause to specify the IP addresses identifying the next 
hop router in the path.

For details about PBR commands and keywords, see the Cisco IOS IP Command Reference, Volume 2 of 
3: Routing Protocols, Release 12.2. For a list of PBR commands that are visible but not supported by the 
switch, see 

This software release does not support PBR when processing IPv4 and IPv6 traffic. 

Before configuring PBR, you should be aware of this information:

To use PBR, you must have the IP services image installed on the switch.

Multicast traffic is not policy-routed. PBR applies to only to unicast traffic.

You can enable PBR on a routed port or an SVI.

The switch does not support route-map deny statements for PBR.