Configuring Pbr; Overview; Policy - HP FlexFabric 12900E Series Configuration Manual

Configuring PBR

Overview

Policy-based routing (PBR) uses user-defined policies to route packets. A policy can specify the next
hop, default next hop, and precedence for packets that match specific criteria such as ACLs.
The 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 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 the following types:
•
Local PBR—Guides the forwarding of locally generated packets, such as ICMP packets
generated by using the ping command.
•
Interface PBR—Guides the forwarding of packets received on an interface.
•
Outbound PBR on a VXLAN tunnel interface—Guides the forwarding of outgoing packets
when equal-cost routes exist.

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 compares packets with nodes in priority order. 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 following types of if-match clauses:
•
if-match acl—Sets an ACL match criterion.
•
if-match vxlan-id—Sets the VXLAN match criterion. For more information about VXLAN, see
VXLAN Configuration Guide.
On a node, you can specify multiple types of if-match clauses. To match a node, a packet must
match all types of the if-match clauses for the node but only one if-match clause for each type.
apply clause
PBR supports the types of apply clauses shown in
for a node, but some of them might not be executed.
Table 22. You can specify multiple apply clauses
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