4-25To do… Use the command… RemarksEnter 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 this commandon both ends of a virtual link.Note that hello and dead intervalsmust be identical on both ends of thevirtual 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.z P2P: When the link layer protocol is PPP, LAPB, HDLC, or POS, OSPF considers the networktype as P2P by default.You can change the network type of an interface as needed. For example:z When an NBMA network becomes fully meshed through address mapping, namely, when any tworouters in the network have a direct virtual link in between, you can change the network type tobroadcast, without manually configuring the neighbors.z When some routers in the broadcast network do not support multicast, you can change thenetwork type to NBMA.z An NBMA network is fully meshed, which means any two routers in the NBMA network have adirect virtual link for communication. If direct connections are not available between some routers,the type of interfaces associated should be configured as P2MP, or as P2P for interfaces with onlyone neighbor.If two interfaces on a link are both configured as the broadcast, NBMA or P2MP type, they cannotestablish a neighbor relationship unless they are on the same network segment.PrerequisitesBefore configuring OSPF network types, you have configured:z IP addresses for interfaces, making neighboring nodes accessible with each other at networklayer.z OSPF basic functions.
