H3C Technologies H3C MSR 5600 - Manual (Page 69)

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Associating Track with PBR
PBR is a routing mechanism based on user-defined policies. Different from the traditional
destination-based routing mechanism, PBR allows you to use a policy (based on such criteria as the
source address and packet length) to route packets. You can specify the VPN instance, packet priority,
outgoing interface, next hop, default outgoing interface, default next hop, and other parameters to guide
the forwarding of packets that match specific ACLs or have specific lengths. For more information about
PBR, see Layer 3—IP Routing Configuration Guide.
PBR cannot detect the availability of any action taken on packets. When an action is not available,
packets processed by the action might be discarded. For example, configure PBR to forward packets that
match certain criteria through a user-specified interface. When the interface fails, PBR cannot sense the
failure, and continues to forward matching packets out of the interface.
This problem can be solved by associating Track with PBR, which improves the flexibility of the PBR
application and enables PBR to sense topology changes.
After you associate a track entry with an apply clause, the detection module associated with the track
entry sends the detection result of the availability of the object (an interface or an IP address) specified
in the apply clause.
• The Positive state of the track entry shows that the object is available, and the apply clause is valid.
• The Negative state of the track entry shows that the object is not available, and the apply clause is
invalid.
• The NotReady state of the track entry shows that the apply clause is valid.
The following objects can be associated with a track entry:
• Outgoing interface.
• Next hop.
• Default outgoing interface.
• Default next hop.
Configuration prerequisites
Before you associate Track with PBR, create a policy or a policy node and configure the match criteria as
well.
Configuration procedure
You can associate a nonexistent track entry with PBR. The association takes effect only after you use the
track command to create the track entry.
To associate Track with PBR:
Step Command Remarks
1. Enter system view. system-view N/A
2. Create a policy or policy
node and enter PBR policy
node view.
policy-based-route policy-name [ deny |
permit ] node node-number
N/A