33
Policy-based Routing (PBR)
Policy-based Routing (PBR) allows a switch to make routing decisions based on policies applied to an
interface.
Overview
When a router receives a packet, the router normally decides where to forward the packet based on the
destination address in the packet, which is used to look up an entry in a routing table. However, in some
cases, there may be a need to forward the packet based on other criteria: size, source, protocol type,
destination, and so forth. For example, a network administrator might want to forward a packet that uses
transmission control protocol (TCP) across a different next-hop than packets using Internet control
message protocol (ICMP). In these situations, you can configure switch route packets according to a
policy applied to interfaces.
When the packet comes from this source and wants to go to that destination, you must route it to this
next-hop or onto that specific interface. This permits routing over different links or towards different
networks when the destination is the same but the packet origins are different.
Policy-based Routing (PBR)
679