RIP Routes May Have a Different Metric Than Expected

• Microsoft Windows NT Server version 4.0
• Microsoft Routing and Remote Access Service Update for Windows NT Server 4.0

SUMMARY

Routes learned from the Routing Information Protocol (RIP) may not have the metrics that you would expect. When a Windows NT Router is advertising a non-RIP route over RIP, it will always be advertised with a metric of 2.

MORE INFORMATION

A metric is a value that shows how desirable a particular route is. Other routing protocols give different meanings to the metric. Because the meanings for the metric are different, the metrics cannot be directly converted. When RIP advertises a non-RIP route, RIP will advertise the route with a metric of 2.

A simple example is a Windows NT router advertising its local subnet routes. Routes for the locally attached LANs will show in the route table with a metric of 1 and the Protocol is Local. This local route will be advertised to a neighbor RIP router with the metric of 2. This neighbor router will then increase the metric for all routes by one to reflect its own hop count to the destination. In this neighbor's route table, you will see the metric of 3 when you would expect to see the metric of 2.