PBR allows performing the following tasks:
Classifying traffic based on the extended access list to identify the match criteria
Rewriting or changing header options such as IP precedence, DF, or ToS bits, influence the next-hop
address or interface
Routing packets to specific traffic-engineered paths
Example 7-15 shows configuration of a PBR and provides details on how to route traffic from different sources to
different next-hops. Traffic can be routed by overwriting the path devised by an IP routing table and setting
various parameters in the packet header, such as the IP precedence or the ToS bit. All packets arriving on the
specified interface matching the match clauses will be subject to the action defined in the set command.
The example shows that all packets arriving from source 1.1.1.1 are forwarded to the next-hop address at
11.11.11.11 with the Precedence bit set to priority, whereas packets arriving from source 2.2.2.2 are forwarded
to a different next-hop address at 22.22.22.22 with the max-throughput TOS (4) bit set. The example also
shows that all TCP packets that arrive with a minimum and maximum packet length of 100 are sent to the Null 0
interface (black holing the packets).
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