The hello-option neighbor-tracking command enables the neighbor tracking function.
The undo hello-option neighbor-tracking command restores the default configuration.
By default, the neighbor tracking function is not enabled.
Usage Scenario
When sending a Hello message, the switch generates a Generation ID and encapsulates it into the message. The Generation ID changes only when the device status changes. In this case, the neighboring device detects the Generation ID change after receiving the Hello message and immediately sends a Join message to the device to update the neighbor relationship. If multiple devices on a shared network segment prepare to send Join messages to the same upstream PIM neighbor, only one device is allowed to send the Join message. After other devices detect the Join message, they do not send Join messages to the upstream neighbor. This means that the upstream neighbor cannot update neighbor relationships with downstream devices after a Generation ID change.
When the switch with neighbor tracking enabled detects Join messages from other devices, the switch still sends the Join messages to the same upstream PIM neighbor.
Prerequisites
IPv6 multicast routing has been enabled using the multicast ipv6 routing-enable command in the system view.
Precautions
This command is valid for only PIM-SM (IPv6).
Neighbor tracking can be implemented only when this function is enabled on all devices on the shared network segment.
The hello-option neighbor-tracking command has the same function as the pim ipv6 hello-option neighnor-tracking command in the interface view. By default, if neighbor tracking is not used on an interface, the neighbor tracking configuration in the PIM-IPv6 view takes effect.