Configuring Equal-Cost IS-IS Routes
Context
Configure load balancing for equal-cost IS-IS routes so that traffic will be evenly balanced among these links.
This mechanism increases the link bandwidth usage and prevents network congestion caused by link overload. However, this mechanism may make traffic management more difficult because traffic will be randomly forwarded.
Configure preference values for equal-cost IS-IS routes so that only the route with the highest preference will be used and the others function as backups.
This configuration facilitates traffic management and improves the network reliability, without the need to change original configurations.
Procedure
- Configure equal-cost IS-IS routes to work in load-balancing mode.
- Run maximum load-balancing number
The maximum number of load-balancing equal-cost IS-IS routes is set.
By default, the maximum number of equal-cost routes on the S6720SI, S6720S-SI, S5730SI, S5730S-EI, S5720S-SI or S5720SI is 8, and the maximum number of equal-cost routes on the S5720EI, S5720HI, S6720S-EI, or S6720EI is 16.
![]()
NOTE: When the number of equal-cost routes is greater than number specified in the maximum load-balancing command, valid routes are selected for load balancing based on the following criteria:- Route preference: Routes with lower preference value (higher preference) are selected for load balancing.
- Next hop System ID: If routes have the same priorities, routes with smaller System ID are selected for load balancing.
- Interface index: If routes have the same priorities and System ID, routes with lower interface index values are selected for load balancing.
- Run maximum load-balancing number
- Configure preference values for equal-cost IS-IS routes.
Previous
