312 CHAPTER 34: OSPF C ONFIGURATIONn ■ You must use the stub command on all the routers connected to a stub area toconfigure the area with the stub attribute.■ You must use the nssa command on all the routers connected to an NSSA areato configure the area with the NSSA attribute.OSPF Network TypeConfigurationOSPF divides networks into four types by link layer protocol. See “OSPF NetworkType” on page 303. An NBMA network must be fully connected. That is, any tworouters in the network must be directly reachable to each other through a virtualcircuit. However, in many cases, this cannot be implemented and you need to usea command to change the network type forcibly.Configure the interface type as P2MP if not all the routers are directly accessibleon an NBMA network. Change the interface type to P2P if the router has only onepeer on the NBMA network.In addition, when configuring a broadcast network or NBMA network, you canalso specify DR priority for each interface to control the DR/BDR selection in thenetwork. Thus, the router with higher performance and reliability can be selectedas a DR or BDR.ConfigurationPrerequisitesBefore configuring the network type of an OSPF interface, perform the followingtasks:■ Configuring the network layer address of the interface so that the adjacentnode is reachable at network layer■ Performing basic OSPF configurationConfiguring theNetwork Type of anOSPF InterfaceCreate and configure a virtual link vlink-peer router-id[ hello seconds |retransmit seconds |trans-delay seconds |dead seconds | simplepassword | md5 keyidkey ]*OptionalFor a virtual link to takeeffect, you need to usethis command at bothends of the virtual link andensure consistentconfigurations of thehello, dead, and otherparameters at both ends.Table 232 Configure OSPF area attributesOperation Command DescriptionTable 233 Configure the network type of an OSPF interfaceOperation Command DescriptionEnter system view system-view -Enter interface view interface interface-typeinterface-number-Configure the network type of theOSPF interfaceospfnetwork-type { broadcast| nbma | p2mp | p2p }OptionalBy default, the networktype of an interfacedepends on the physicalinterface.
