Policy-based routing (PBR) is a feature that enables flexible routing based on policies rather than on static routing protocols. PBR allows you to override the traditional routing table's decision based on packet attributes such as source address, destination address, source port, or other protocol-level information.
PBR is a flexible substitute for traditional routing protocols such as OSPF, BGP and so on. Instead of routing all traffic according to a single set of routing rules, PBR allows network engineers to apply specific policies to different types of traffic, giving more granular and flexible control over network traffic. Policies are created based on various criteria such as source IP address, destination IP address, application type, or protocol type.
For example, certain traffic can be routed over a higher bandwidth connection, while other traffic can be routed over a different path that may have lower latency or specific security policies. PBR operates by matching traffic to predefined policies and then applying a specific route map to it. Route maps contain a set of rules designed to modify routing behavior based on the selected policy. The rules in the route map can perform actions like matching based on specific criteria, setting a next-hop address, or modifying the source or destination IP address of the packet.
There are various advantages of using PBR in network infrastructures:
- Greater network control and flexibility: PBR offers granular control over network traffic and gives network engineers more fine-tuned control to manage routing behavior based on specific business needs.
- Better network security: PBR gives network administrators the capability to route traffic through specific security policies and firewalls, enabling higher network security
- Interdependent traffic load sharing: PBR can enable organizations with multiple entry points, to break internal traffic away from external traffic and offer more precise load sharing.
