Dell PowerConnect B-RX BigIron RX Series Configuration Guide v02.7.02 - Page 781

Configuring OSPF 25 Syntax: metric-type type1 | type2 The default is type2. Modify administrative distance The device can learn about networks from various protocols, including Border Gateway Protocol version 4 (BGP4), RIP, ISIS, and OSPF. Consequently, the routes to a network may differ depending on the protocol from which the routes were learned. The default administrative distance for OSPF routes is 110. Refer to "Changing administrative distances" on page 765 for a list of the default distances for all route sources. The router selects one route over another based on the source of the route information. To do so, the router can use the administrative distances assigned to the sources. You can bias the device's decision by changing the default administrative distance for OSPF routes. Configuring administrative distance based on route type You can configure a unique administrative distance for each type of OSPF route. For example, you can use this feature to prefer a static route over an OSPF inter-area route but you also want to prefer OSPF intra-area routes to static routes. The distance you specify influences the choice of routes when the device has multiple routes for the same network from different protocols. The device prefers the route with the lower administrative distance. You can specify unique default administrative distances for the following route types: • Intra-area routes • Inter-area routes • External routes The default for all these OSPF route types is 110. NOTE This feature does not influence the choice of routes within OSPF. For example, an OSPF intra-area route is always preferred over an OSPF inter-area route, even if the intra-area route's distance is greater than the inter-area route's distance. To change the default administrative distances for inter-area routes, intra-area routes, and external routes, enter the following command. BigIron RX(config-ospf-router)# distance external 100 BigIron RX(config-ospf-router)# distance inter-area 90 BigIron RX(config-ospf-router)# distance intra-area 80 Syntax: distance external | inter-area | intra-area The external | inter-area | intra-area parameter specifies the route type for which you are changing the default administrative distance. The parameter specifies the new distance for the specified route type. Unless you change the distance for one of the route types using commands such as those shown above, the default is 110. BigIron RX Series Configuration Guide 709 53-1001810-01