HP 6125XLG R2306-HP 6125XLG Blade Switch Layer 3 - IP Routing Configuration Gu - Page 279

Configuring PBR Introduction to PBR Policy-based routing (PBR) uses user-defined policies to route packets. A policy can specify the next hop and other parameters for packets that match specific criteria, such as ACLs. A device uses PBR to forward matching packets and uses the routing table to forward other packets. If PBR is not configured, the device uses the routing table to forward packets. The device supports only interface PBR, which guides the forwarding of packets received on an interface only. Policy A policy comprises match criteria and actions to be taken on the matching packets. A policy can have one or multiple nodes as follows: • Each node is identified by a node number. A smaller node number has a higher priority. • A node comprises if-match and apply clauses. An if-match clause specifies a match criterion, and an apply clause specifies an action. • A node has a match mode of permit or deny. A policy matches nodes in priority order against packets. If a packet satisfies the match criteria on a node, it is processed by the action on the node. Otherwise, it goes to the next node for a match. If the packet does not match the criteria on any node, it is forwarded according to the routing table. if-match clause PBR supports only the if-match acl clause, which sets an ACL match criterion. You can specify only one if-match clause of each type for a node. apply clause PBR supports only the apply next-hop clause, which sets the next hop for packets. Relationship between the match mode and clauses on the node Does a packet match all the if-match clauses on the node? Yes. No. Match mode permit Deny • If the node is configured with an apply clause, PBR executes the apply clause on the node. The packet is forwarded according • If the node is configured with no to the routing table. apply clause, the packet is forwarded according to the routing table. PBR matches the packet against the next PBR matches the packet against the node. next node. 268