Supported Platforms
Configuring the Reference Bandwidth Used in IS-IS Metric Calculations
All IS-IS interfaces have a cost, which is a routing metric that is used in the IS-IS link-state calculation. Routes with lower total path metrics are preferred over those with higher path metrics. When there are several equal-cost routes to a destination, traffic is distributed equally among them.
The cost of a route is described by a single dimensionless metric that is determined using the following formula:
To modify the reference bandwidth, include the reference-bandwidth statement:
For a list of hierarchy levels at which you can include this statement, see the statement summary section for this statement.
reference-bandwidth is the reference bandwidth. If the reference bandwidth is not configured, all interfaces have a default metric of 10 (with the exception of the lo0 interface, which has a default metric of 0).
For example, if you set the reference bandwidth to 1 Gbps (that is, reference-bandwidth is set to 1,000,000,000), a 100-Mbps interface has a default metric of 10.
For more information about IS-IS route metrics, see Configuring Levels on IS-IS Interfaces.
