H3C Technologies H3C SecPath F1000-E - Manual (Page 285)

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Collaboration Between the Track Module and the Detection
Modules
With the collaboration between the track module and the detection modules, the detection modules
probe the interface status or link status, and inform the track module of the probe results. The track
module then changes the status of the track entry accordingly:
• If the probe succeeds, the status of the corresponding track entry is Positive;
• If the probe fails, the status of the corresponding track entry is Negative.
NOTE:
If the probe result is invalid (for example, the NQA test group collaborating with the track entry does not
exist.), the status of the track entry is Invalid.
At present, the detection modules that can collaborate with the track module include the Network
Quality Analyzer (NQA) module, the Bidirectional Forwarding Detection (BFD) module and the
interface management module.
• For more information about NQA, see NQA Configuration in the System Volume.
• The interface management module is used to monitor the physical status or Layer 3 protocol status
of an interface. When the physical status or Layer 3 protocol status of an interface is up, the status
of a track entry is Positive; when the physical status or Layer 3 protocol status of an interface is
down, the status of a track entry is Negative.
Collaboration Between the Track Module and the Application
Modules
With the collaboration between the track module and the application modules, if the status of the track
entry changes, the track module notifies the application modules to deal with the change accordingly.
At present, the application modules that can collaborate with the track module include:
• Virtual Router Redundancy Protocol (VRRP)
• Static routing
• Policy routing
• Interface backup
In some cases, when the status of the track entry changes, if the track module notifies the application
modules immediately, communication may be interrupted because routes cannot be recovered in time.
For example, the master in a VRRP group monitors the uplink interface through the track module. When
the uplink interface fails, the track module notifies the master to reduce its priority so that a backup with
a higher priority can preempt as the master to forward packets. When the uplink interface recovers, if
the track module notifies the original master to restore its priority immediately, the master will forward
packets immediately; however, the uplink route has not been recovered yet, which may result in packet