Hi,
As we know, when a routing table has a large number of routing entries on an IS-IS device, it takes a long time to implement the SPF calculation on the device. The prefix-priority command can be used to allow some key routes to be preferentially calculated.
The convergence priorities of IS-IS routes can be critical, high, medium, and low. The priorities are listed in descending order.
The convergence priority of IS-IS routes is used as follows:
l For the existing IS-IS routes, IS-IS resets the convergence priority for the routes based on the prefix-priority command.
l For the newly added IS-IS routes, IS-IS sets the convergence priority for the routes based on the filtering result of the prefix-priority command.
l If an IS-IS route matches the matching rules of multiple convergence priorities, the highest convergence priority is used.
l If an IS-IS route matches tags of multiple convergence priorities, the highest convergence priority is used.
l If the route level is not specified, IS-IS configures convergence priorities for both Level-1 routes and Level-2 routes.
If we need to configure the priority of a route, you can first label the route and then set the priority of the label in IS-IS.
The configuration example is as below:
#
interface loopback 0
isis tag-value 100
#
isis 1
prefix-priority level-2 high tag 100
#
commit
#
That's all for the example.
If you have any further questions, kindly let us know.
