Configuring OSPF and OSPFv3 983Configuring Virtual LinksBeginning in Privileged EXEC mode, use the following commands toconfigure OSPF Virtual Links.Command Purposeconfigure Enter global configuration mode.router ospf Enter OSPF configuration mode.areaarea-id virtual-linkneighbor-idCreate the OSPF virtual interface for the specified area-id and neighbor router. Theneighbor-id variable is the IPaddress of the neighboring router.areaarea-id virtual-linkrouter-id [authentication[message-digest | null]][[authentication-keykey]| [message-digest-keykey-id md5key]]Create the OSPF virtual interface for the specified area-id and neighbor router.Use the optional parameters to configure authenticationfor the virtual link. If the area has not been previouslycreated, it is created by this command. If the area alreadyexists, the virtual-link information is added or modified.• authentication—Specifies authentication type.• message-digest—Specifies that message-digestauthentication is used.• null—No authentication is used. Overrides password ormessage-digest authentication if configured for thearea.• md5—Use MD5 Encryption for an OSPF Virtual Link•key—Authentication key for the specified interface.(Range: 8 bytes or less if the authentication type issimple and 16 bytes or less if the type is encrypt.)•key-id—Authentication key identifier for theauthentication type encrypt. (Range: 0-255)areaarea-id virtual-linkneighbor-id retransmit-intervalsecondsSet the OSPF retransmit interval for the virtual linkinterface.Theseconds variable is the number of seconds to waitbetween retransmitting LSAs if no acknowledgement isreceived. (Range: 0–3600)
