Configuring pbr, Overview, Policy – H3C Technologies H3C S5560 Series Switches User Manual

Page 343: If-match clause, Apply clause

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Configuring PBR

Overview

Policy-based routing (PBR) uses user-defined policies to route packets. A policy can specify the next hop

for packets that match specific criteria such as ACLs.
A device forwards received packets using the following process:

1.

The device uses PBR to forward matching packets.

2.

If the packets do not match the PBR policy or the PBR-based forwarding fails, the device uses the
routing table, excluding the default route, to forward the packets.

3.

If the routing table-based forwarding fails, the device uses the default next hop or default output
interface defined in PBR to forward packets.

4.

If the default next hop or default output interface-based forwarding fails, the device uses the default
route to forward packets.

PBR includes local PBR and interface PBR.

Local PBR guides the forwarding of locally generated packets, such as the ICMP packets generated
by using the ping command.

Interface PBR guides the forwarding of packets received on an interface only.

Policy

A policy includes 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 contains 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 matches the 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 the if-match acl clause to set an ACL match criterion. You can specify only one if-match acl
clause for a node.

apply clause

PBR supports the apply next-hop clause to set next hops for packets.

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