4-21Configuring OSPF to Redistribute External RoutesFollow these steps to configure OSPF to redistribute external routes:To do... Use the command... RemarksEnter system view system-view —Enter OSPF view ospf [ process-id [ router-idrouter-id ] ] —Configure OSPF toredistribute routes fromanother protocolimport-route protocol [ process-id ][ cost value | type value | tag value |route-policy route-policy-name ] *RequiredBy default, OSPF does notimport the routing informationof other protocols.Configure OSPF to filteroutgoing routesfilter-policy { acl-number | ip-prefixip-prefix-name } export [ protocol ]OptionalBy default, OSPF does not filteradvertised routes.Enable OSPF to importthe default routedefault-route-advertise [ always |cost value | type type-value |route-policy route-policy-name ]*OptionalBy default, OSPF does notimport the default route.Configure the defaultparameters forredistributed routes,including cost, interval,limit, tag, and typedefault { cost value | intervalseconds | limit routes | tag tag | typetype } *OptionalThese parameters respectivelydefault to:z Cost: 1z Interval: 1 (second)z Limit: 1000z Tag: 1z Type: 2z The import-route command cannot import the default route. To import the default route, you mustuse the default-route-advertise command.z The filtering of advertised routes by OSPF means that OSPF only converts the external routesmeeting the filter criteria into Type-5 or Type-7 LSAs and advertises them.z When enabling OSPF to import external routes, you can also configure the defaults of someadditional parameters, such as cost, limit, tag, and type. A route tag can be used to identifyprotocol-related information.OSPF Network Adjustment and OptimizationYou can adjust and optimize an OSPF network in the following aspects:z By changing the OSPF packet timers, you can adjust the convergence speed of the OSPF networkand the network load brought by OSPF packets. On some low-speed links, you need to considerthe delay experienced when the interfaces transmit LSAs.
