1-26To do… Use the command… RemarksSpecify a cost for the defaultroute advertised to the NSSAareadefault-cost cost OptionalDefaults to 1.z It is required to use the nssa command on all the routers attached to an NSSA area.z Using the default-cost command only takes effect on the ABR/ASBR of an NSSA area.Configuring a Virtual LinkNon-backbone areas exchange routing information via the backbone area. Therefore, connectivitybetween the backbone and non-backbone areas and within the backbone itself must be maintained.If necessary physical links are not available for this connectivity maintenance, you can configure virtuallinks to solve it.Follow these steps to configure a virtual link:To do… Use the command… RemarksEnter system view system-view —Enter OSPF viewospf [ process-id | router-idrouter-id | vpn-instanceinstance-name ] *—Enter area view area area-id —Configure a virtual linkvlink-peer router-id [ helloseconds | retransmit seconds |trans-delay seconds | deadseconds | simple [ plain |cipher ] password | { md5 |hmac-md5 } key-id [ plain |cipher ] password ] *RequiredYou need to configure thiscommand on both ends of avirtual link.Note that hello and deadintervals must be identical onboth ends of the virtual link.Configuring OSPF Network TypesOSPF classifies networks into four types: broadcast, NBMA, P2MP, and P2P, upon the link layerprotocol.z Broadcast: When the link layer protocol is Ethernet or FDDI, OSPF considers the network type asbroadcast by default.z NBMA: When the link layer protocol is Frame Relay, ATM or X.25, OSPF considers the networktype as NBMA by default.
