OSPF Metrics (Cost)

Earlier, the “Calculating the Best Routes with SPF” section discussed how SPF calculates the metric for each route, choosing the route with the best metric for each destination subnet. OSPF routers can influence that choice by changing the OSPF interface cost on any and all interfaces.

Cisco routers allow two different ways to change the OSPF interface cost. The one straightforward way is to set the cost directly, with an interface subcommand: ip ospf cost x. The other method is to let IOS choose default costs, based on a formula, but to change the inputs to the formula. This second method requires a little more thought and care and is the focus of this next topic.

Setting the Cost Based on Interface Bandwidth

The default ...

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