If multiple routes to the same destination are discovered by different routing protocols, configuring the highest preference value for IS-IS allows a route discovered by IS-IS to be selected preferentially.
If multiple equal-cost IS-IS routes are available on a network, configure the equal-cost IS-IS routes to work in load-balancing mode to increase the bandwidth usage of each link.
If an IS-IS device needs to be temporarily isolated, configure the IS-IS device to enter the overload state to prevent other devices from forwarding traffic to this IS-IS device and prevent blackhole routes.