Configuring a Reference Bandwidth to Set a Default Metric

By default, all IS-IS interfaces without a configured metric have the same routing metric, 10, However, when you configure a reference bandwidth for IS-IS, the default metric is calculated differently for each IS-IS interface. The default routing metric in this case is the reference bandwidth divided by the bandwidth of the particular interface.

For example, if you set the IS-IS reference bandwidth to 50,000,000, the default metric for a 10-Mbps interface is calculated as 5. Interfaces with lower bandwidths have higher default metrics than this interface. Similarly, links with higher bandwidths have lower default metrics than this interface.

reference-bandwidth

• Use to set a reference bandwidth from which a default metric can be calculated by IS-IS for interfaces without a configured metric.
• Example

  host1(config-router)#reference-bandwidth 100000000

• Use the no version to remove the reference bandwidth. When you do so, the default metric reverts to 10.
• See reference-bandwidth

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