Configuring OSPF,Configuring OSPF Routing,router ospf process-id vrf vpn-name,Router(config)#,Enables one or more OSPF routing processes,Configuring Basic OSPF,network ip-address wildcard-mask area area-id,Router(config-router)#,Defines the interfaces that OSPF will run on,Router(config-if)#,ip ospf process-id area area-id secondaries none,Optional method to enable OSPF explicitly on an interface,Configuring OSPF on Internal Routers of a Single Area,Configuring OSPF for Multiple Areas,network 10.1.2.1 0.0.0.0 area 1,OSPF Router ID,The router is known to OSPF by the OSPF router ID number.LSDBs use the OSPF router ID to differentiate one router from the next.By default, the router ID is the highest IP address on an active interface at the moment of OSPF process startup.A loopback interface can override the OSPF router ID. If a loopback interface exists, the router ID is the highest IP address on any active loopback interface.The OSPF router-id command can be used to override the OSPF router ID.Using a loopback interface or a router-id command is recommended for stability.,Router(config)#interface loopback 0Router(config-if)#ip address 172.16.17.5 255.255.255.255,If the OSPF process is already running, the router must be reloaded or the OSPF process must be removed and reconfigured before the new loopback address will take effect.,Loopback Interfaces,router-id ip-address,This command is configured under the router ospf process-id command.Any unique arbitrary 32-bit value in an IP address format (dotted decimal) can be used.If this command is used on an OSPF process that is already active, then the new router ID is used after the next reload or manual OSPF process restart using:,OSPF router-id Command,Router(config-router)#,Router(config)#router ospf 1Router(config-router)#router-id 172.16.1.1Router#clear ip ospf process,clear ip ospf process,Router#,OSPF Router ID Verification,RouterB#sh ip ospf Routing Process ospf 50 with ID 10.64.0.2 Number of areas in this router is 2. 2 normal 0 stub 0 nssa Number of areas transit capable is 0 External flood list length 0 Area BACKBONE(0) Area BACKBONE(0) Area has no authentication SPF algorithm last executed 00:01:25.028 ago SPF algorithm executed 7 times Area 1 Number of interfaces in this area is 1 Area has no authentication SPF algorithm last executed 00:00:54.636 ago SPF algorithm executed 3 times,show ip protocols,Router#,Verifies the configured IP routing protocol processes, parameters, and statistics,Verifying OSPF Operation,show ip route ospf process-id ,Router#,Displays all OSPF routes learned by the router,show ip ospf interface type number,Router#,Displays the OSPF router ID, area ID, and adjacency information,show ip ospf,Router#,Displays the OSPF router ID, timers, and statistics,Verifying OSPF Operation (Cont.),show ip ospf neighbor type number neighbor-id detail,Router#,Displays information about the OSPF neighbors, including DR and BDR information on broadcast networks,Example: The show ip route ospf Command,RouterA#show ip route ospf 10.0.0.0/8 is variably subnetted, 3 subnets, 2 masksO IA 10.2.1.0/24 110/782 via 10.64.0.2, 00:03:05, FastEthernet0/0RouterA#,Example: The show ip ospf interface Command,RouterA#show ip ospf interface fastEthernet 0/0FastEthernet0/0 is up, line protocol is up Internet Address 10.64.0.1/24, Area 0 Process ID 1, Router ID 10.64.0.1, Network Type BROADCAST, Cost: 1 Transmit Delay is 1 sec, State DROTHER, Priority 0 Designated Router (ID) 10.64.0.2, Interface address 10.64.0.2 No backup designated router on this network Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 oob-resync timeout 40 Hello due in 00:00:04 Supports Link-local Signaling (LLS) Index 1/1, flood queue length 0 Next 0x0(0)/0x0(0) Last flood scan length is 1, maximum is 4 Last flood scan time is 0 msec, maximum is 4 msec Neighbor Count is 1, Adjacent neighbor count is 1 Adjacent with neighbor 10.64.0.2 (Designated Router) Suppress hello for 0 neighbor(s),Example: The show ip ospf neighbor Command,RouterB# show ip ospf neighborNeighbor ID Pri State Dead Time Address Interface10.64.0.1 0 FULL/DROTHER 00:00:30 10.64.0.1 FastEthernet0/010.2.1.1 0 FULL/ - 00:00:34 10.2.1.1 Serial0/0/1,RouterB# show ip ospf neighbor detail Neighbor 10.64.0.1, interface address 10.64.0.1 In the area 0 via interface FastEthernet0/0 Neighbor priority is 0, State is FULL, 16 state changes DR is 10.64.0.2 BDR is 0.0.0.0Neighbor 10.2.1.1, interface address 10.2.1.1 In the area 1 via interface Serial0/0/1 Neighbor priority is 0, State is FULL, 6 state changes DR is 0.0.0.0 BDR is 0.0.0.0,Summary,Configuration of OSPF is a two-step process:Enter OSPF configuration with the router ospf command.Use the network command to describe which interfaces will run OSPF in which area.OSPF selects a router ID at startup time: The router IDs specified in the router-id command under the OSPF process.Otherwise, the highest IP address of a loopback interface, if there are any, is used.By default, the highest IP address of all active interfacesUse the show ip ospf command to verify the router ID.Use the show ip protocols, show ip route ospf, show ip ospf interface, show ip ospf, and show ip ospf neighbor commands to verify OSPF operation.,