Overview of PBR
Definition
Policy-based routing (PBR) allows switches to select routes based on user-defined policies, and it takes precedence over direct routes, static routes, and routes generated by dynamic routing protocols. After PBR is configured on the device, if the received packets (including Layer 2 packets) match PBR rules, the device forwards the packets according to the rules. If the packets do not match PBR rules, the device forwards the packets according to the destination address of the packets.
- PBR changes the forwarding path of packets based on user-defined policies instead of based on the routes in an IP routing table.
- Routing policies change the forwarding path of packets by filtering routes and setting route attributes. For example, route attributes (including reachability) can be set to change the forwarding path of network traffic.
Purpose
Traditionally, to determine the routes used to forward packets, a switch searches its IP routing table based on the destination address carried in the packets. To allow switches to route packets based on user-defined policies, PRB can be configured.
Benefits
PBR has the following advantages:
- Allows network administrators to define policies for routing packets, improving route selection flexibility.
- Enables different data flows to be forwarded on different links, increasing link efficiency.
- Allows cost-effective links to be used for transmitting service data without affecting service quality, reducing the cost of enterprise data services.