In a Huawei network, which command is used to track an ISIS session for VRRP?

The command used to track an ISIS session for VRRP is specifically designed to integrate the VRRP (Virtual Router Redundancy Protocol) with the BFD (Bidirectional Forwarding Detection) session. In this context, the correct command allows the VRRP instance to monitor the state of the ISIS session, enabling it to change its operational state based on the status of the BFD session. This provides a more efficient mechanism for failover and improves network resilience by ensuring that the virtual router remains active only when the underlying routing protocol (ISIS) is functioning correctly.

The command incorporates essential parameters such as specifying the VRID (Virtual Router ID) and the reduction value, which indicates how VRRP should respond if the tracked session goes down. This ensures the network can react promptly to failures, maintaining high availability.

The other options do not use the correct syntax or parameters required for tracking an ISIS session specifically in conjunction with VRRP, contributing to their incorrectness. The absence of the BFD session specification, or incorrect command structure, means they cannot effectively achieve the desired tracking functionality for VRRP in this scenario.