Configuring Equal-Cost IPv6 IS-IS Routes

Context

If there are redundant IS-IS links, multiple routes may have an equal cost.

Configure load balancing among 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.

Procedure

Configure load balancing among equal-cost IS-IS routes.
1. Run system-view
  The system view is displayed.
2. Run isis [ process-id ]
  The IS-IS view is displayed.
3. Run ipv6 maximum load-balancing number
  The maximum number of equal-cost IPv6 IS-IS routes for load-balancing is set.
  
  By default, load balancing is supported and a maximum of 8 equal-cost routes can participate in load balancing.
  When the number of equal-cost routes is larger than the value specified in the ipv6 maximum load-balancing command, valid routes are selected for load balancing based on the following criteria:
  Route preference: Routes with higher preferences are selected for load balancing.
  Next hop system ID: If routes have the same preference, routes with smaller system IDs are selected for load balancing.
  Interface index: If routes have the same preference and system ID, routes with lower interface index values are selected for load balancing.