Dell Force10 MXL Blade MXL 10/40GbE Switch IO Module Configuration Guide - Page 373

Loopback interfaces also assist in the OSPF process. OSPF picks the highest interface address as the router-id and a loopback interface address has a higher precedence than other interface addresses. Figure 20-11 shows the show ip ospf process-id interface command with a loopback interface. Figure 20-11. show ip ospf process-id interface Command Example FTOS#show ip ospf 1 int TenGigabitEthernet 13/23 is up, line protocol is up Internet Address 10.168.0.1/24, Area 0.0.0.1 Process ID 1, Router ID 10.168.253.2, Network Type BROADCAST, Cost: 1 Transmit Delay is 1 sec, State DROTHER, Priority 1 Designated Router (ID) 10.168.253.5, Interface address 10.168.0.4 Backup Designated Router (ID) 192.168.253.3, Interface address 10.168.0.2 Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 Hello due in 00:00:08 Neighbor Count is 3, Adjacent neighbor count is 2 Adjacent with neighbor 10.168.253.5 (Designated Router) Adjacent with neighbor 10.168.253.3 (Backup Designated Router) Loopback 0 is up, line protocol is up Internet Address 10.168.253.2/32, Area 0.0.0.1 Process ID 1, Router ID 10.168.253.2, Network Type LOOPBACK, Cost: 1 Loopback interface is treated as a stub Host. FTOS# Configure Stub Areas OSPF supports different types of LSAs to help reduce the amount of router processing within the areas. Type 5 LSAs are not flooded into stub areas; the ABR advertises a default route into the stub area to which it is attached. Stub area routers use the default route to reach external destinations To ensure connectivity in your OSPFv2 network, never configure the backbone area as a stub area. To configure a stub area, follow these steps, starting in EXEC Privilege mode. Step 1 2 3 4 Command Syntax Command Mode Usage show ip ospf process-id database database-summary EXEC Privilege Review all areas after they were configured to determine which areas are NOT receiving type 5 LSAs. configure EXEC Privilege Enter CONFIGURATION mode. router ospf process-id area area-id stub [no-summary] CONFIGURATION CONFIG-ROUTER-O SPF-id Enter ROUTER OSPF mode. Process ID is the ID assigned when configuring OSPFv2 globally. Configure the area as a stub area. To prevent transmission to the area of summary ASBR LSAs., use the keywords no-summary. Area ID is the number or IP address assigned when creating the Area. Open Shortest Path First (OSPFv2) | 371