Collaboration fundamentals
The Track module collaborates with detection modules and application modules.
Collaboration between the Track module and a detection module
The detection module sends the detection result of the tracked object to the Track module. The Track module changes the status of the track entry as follows:
If the tracked object operates correctly, the state of the track entry is Positive. For example, the track entry state is Positive in one of the following conditions:
The target interface is up.
The target network is reachable.
If the tracked object does not operate correctly, the state of the track entry is Negative. For example, the track entry state is Negative in one of the following conditions:
The target interface is down.
The target network is unreachable.
If the detection result is invalid, the state of the track entry is NotReady. For example, the track entry state is NotReady if its associated NQA operation does not exist.
The following detection modules can be associated with the Track module:
NQA.
BFD.
CFD.
Interface management.
Route management.
LLDP.
Collaboration between the Track module and an application module
The following application modules can be associated with the Track module:
VRRP.
Static routing.
PBR.
Smart Link.
EVI IS-IS.
VPLS.
VXLAN.
MPLS L2VPN.
EAA.
ERPS.
When configuring a track entry for an application module, you can set a notification delay to avoid immediate notification of status changes.
When the delay is not configured and the route convergence is slower than the link state change notification, communication failures occur. For example, when the master in a VRRP group detects an uplink interface failure through Track, Track immediately notifies the master to decrease its priority. A backup with a higher priority then preempts as the new master. When the failed uplink interface recovers, the Track module immediately notifies the original master to restore its priority. If the uplink route has not recovered, forwarding failure will occur.