Example for Configuring Basic OSPF Functions
This section describes how to configure basic OSPF functions, including enabling OSPF on each router and specifying network segments in different areas.
Networking Requirements
On the network shown in Figure 1, all routers run OSPF, and the entire AS is divided into three areas. Device A and Device B function as ABRs to forward inter—area routes.
After the configuration is complete, each router should learn the routes to all network segments in the AS.
Precautions
When configuring basic OSPF functions, note the following rules:
The backbone area is responsible for forwarding inter-area routes. In addition, the routing information between non-backbone areas must be forwarded through the backbone area. OSPF defines the following rules for the backbone area:
- Connectivity must be available between non-backbone areas and the backbone area.
- Connectivity must be available over the backbone area.
- The intervals at which Hello, Dead, and Poll packets are sent on the local interface must be the same as those on the remote interface. Otherwise, the OSPF neighboring relationship cannot be established.
Configuration Roadmap
The configuration roadmap is as follows:
Enable OSPF on each router.
Specify network segments in different areas.
Data Preparation
To complete the configuration, you need the following data:
Device Name |
Router ID |
Process ID |
IP Address |
Device A |
1.1.1.1 |
1 |
Area 0: 192.168.0.0/24 Area 1: 192.168.1.0/24 |
Device B |
2.2.2.2 |
1 |
Area 0: 192.168.0.0/24 Area 2: 192.168.2.0/24 |
Device C |
3.3.3.3 |
1 |
Area 1: 192.168.1.0/24 and 172.16.1.0/24 |
Device D |
4.4.4.4 |
1 |
Area 2: 192.168.2.0/24 and 172.17.1.0/24 |
Device E |
5.5.5.5 |
1 |
Area 1: 172.16.1.0/24 |
Device F |
6.6.6.6 |
1 |
Area 2: 172.17.1.0/24 |
Procedure
- Assign an IP address to each interface. For configuration details, see Configuration Files in this section.
- Configure basic OSPF functions.
# Configure Device A.
[~DeviceA] router id 1.1.1.1 [~DeviceA] ospf 1 [*DeviceA-ospf-1] area 0 [*DeviceA-ospf-1-area-0.0.0.0] network 192.168.0.0 0.0.0.255 [*DeviceA-ospf-1-area-0.0.0.0] quit [*DeviceA-ospf-1] area 1 [*DeviceA-ospf-1-area-0.0.0.1] network 192.168.1.0 0.0.0.255 [*DeviceA-ospf-1-area-0.0.0.1] quit [*DeviceA-ospf-1] commit
# Configure Device B.
[~DeviceB] router id 2.2.2.2 [~DeviceB] ospf 1 [*DeviceB-ospf-1] area 0 [*DeviceB-ospf-1-area-0.0.0.0] network 192.168.0.0 0.0.0.255 [*DeviceB-ospf-1-area-0.0.0.0] quit [*DeviceB-ospf-1] area 2 [*DeviceB-ospf-1-area-0.0.0.2] network 192.168.2.0 0.0.0.255 [*DeviceB-ospf-1-area-0.0.0.2] quit [*DeviceB-ospf-1] commit
# Configure Device C.
[~DeviceC] router id 3.3.3.3 [~DeviceC] ospf 1 [*DeviceC-ospf-1] area 1 [*DeviceC-ospf-1-area-0.0.0.1] network 192.168.1.0 0.0.0.255 [*DeviceC-ospf-1-area-0.0.0.1] network 172.16.1.0 0.0.0.255 [*DeviceC-ospf-1-area-0.0.0.1] commit [~DeviceC-ospf-1-area-0.0.0.1] quit
# Configure Device D.
[~DeviceD] router id 4.4.4.4 [~DeviceD] ospf 1 [*DeviceD-ospf-1] area 2 [*DeviceD-ospf-1-area-0.0.0.2] network 192.168.2.0 0.0.0.255 [*DeviceD-ospf-1-area-0.0.0.2] network 172.17.1.0 0.0.0.255 [*DeviceD-ospf-1-area-0.0.0.2] commit [~DeviceD-ospf-1-area-0.0.0.2] quit
# Configure Device E.
[~DeviceE] router id 5.5.5.5 [~DeviceE] ospf 1 [*DeviceE-ospf-1] area 1 [*DeviceE-ospf-1-area-0.0.0.1] network 172.16.1.0 0.0.0.255 [*DeviceE-ospf-1-area-0.0.0.1] commit [~DeviceE-ospf-1-area-0.0.0.1] quit
# Configure Device F.
[~DeviceF] router id 6.6.6.6 [~DeviceF] ospf 1 [*DeviceF-ospf-1] area 2 [*DeviceF-ospf-1-area-0.0.0.2] network 172.17.1.0 0.0.0.255 [*DeviceF-ospf-1-area-0.0.0.2] commit [~DeviceF-ospf-1-area-0.0.0.2] quit
- Verify the configuration.
# Display the OSPF neighbors of Device A.
[~DeviceA] display ospf peer (M) Indicates MADJ interface OSPF Process 1 with Router ID 1.1.1.1 Neighbors Area 0.0.0.0 interface 192.168.0.1(GigabitEthernet0/1/0)'s neighbors Router ID: 2.2.2.2 Address: 192.168.0.2 State: Full Mode:Nbr is Master Priority: 1 DR: 192.168.0.2 BDR: 192.168.0.1 MTU: 0 Dead timer due in 36 sec Retrans timer interval: 5 Neighbor is up for 1h15m4s Neighbor up time : 2020-06-08 01:41:57 Authentication Sequence: [ 0 ] Area 0.0.0.1 interface 192.168.1.1(GigabitEthernet0/1/8)'s neighbors Router ID: 3.3.3.3 Address: 192.168.1.2 State: Full Mode:Nbr is Master Priority: 1 DR: 192.168.1.2 BDR: 192.168.1.1 MTU: 0 Dead timer due in 39 sec Retrans timer interval: 5 Neighbor is up for 1h15m4s Neighbor up time : 2020-06-08 01:41:57 Authentication Sequence: [ 0 ]
# Display the OSPF routes of DeviceA.
[~DeviceA] display ospf routing OSPF Process 1 with Router ID 1.1.1.1 Routing Tables Routing for Network Destination Cost Type NextHop AdvRouter Area 172.16.1.0/24 2 Transit 192.168.1.2 3.3.3.3 0.0.0.1 172.17.1.0/24 3 Inter-area 192.168.0.2 2.2.2.2 0.0.0.0 192.168.2.0/24 2 Inter-area 192.168.0.2 2.2.2.2 0.0.0.0 Total Nets: 3 Intra Area: 1 Inter Area: 2 ASE: 0 NSSA: 0
# Display the LSDB of Device A.
[~DeviceA] display ospf lsdb OSPF Process 1 with Router ID 1.1.1.1 Link State Database Area: 0.0.0.0 Type LinkState ID AdvRouter Age Len Sequence Metric Router 1.1.1.1 1.1.1.1 93 48 80000004 1 Router 2.2.2.2 2.2.2.2 92 48 80000004 1 Sum-Net 172.16.1.0 1.1.1.1 1287 28 80000002 2 Sum-Net 192.168.1.0 1.1.1.1 1716 28 80000001 1 Sum-Net 172.17.1.0 2.2.2.2 1336 28 80000001 2 Sum-Net 192.168.2.0 2.2.2.2 87 28 80000002 1 Area: 0.0.0.1 Type LinkState ID AdvRouter Age Len Sequence Metric Router 1.1.1.1 1.1.1.1 1420 48 80000002 1 Router 3.3.3.3 3.3.3.3 1294 60 80000003 1 Router 5.5.5.5 5.5.5.5 1296 36 80000002 1 Network 172.16.1.1 3.3.3.3 1294 32 80000001 0 Sum-Net 172.17.1.0 1.1.1.1 1325 28 80000001 3 Sum-Net 192.168.0.0 1.1.1.1 1717 28 80000001 1 Sum-Net 192.168.2.0 1.1.1.1 1717 28 80000001 2
# Display the routing table on Device D and perform the ping operation to test the connectivity.
[~DeviceD] display ospf routing OSPF Process 1 with Router ID 4.4.4.4 Routing Tables Routing for Network Destination Cost Type NextHop AdvRouter Area 172.16.1.0/24 4 Inter-area 192.168.2.1 2.2.2.2 0.0.0.2 192.168.0.0/24 2 Inter-area 192.168.2.1 2.2.2.2 0.0.0.2 192.168.1.0/24 3 Inter-area 192.168.2.1 2.2.2.2 0.0.0.2 Total Nets: 3 Intra Area: 0 Inter Area: 3 ASE: 0 NSSA: 0 [~DeviceD] ping 172.16.1.1 PING 172.16.1.1: 56 data bytes, press CTRL_C to break Reply from 172.16.1.1: bytes=56 Sequence=1 ttl=253 time=62 ms Reply from 172.16.1.1: bytes=56 Sequence=2 ttl=253 time=16 ms Reply from 172.16.1.1: bytes=56 Sequence=3 ttl=253 time=62 ms Reply from 172.16.1.1: bytes=56 Sequence=4 ttl=253 time=94 ms Reply from 172.16.1.1: bytes=56 Sequence=5 ttl=253 time=63 ms --- 172.16.1.1 ping statistics --- 5 packet(s) transmitted 5 packet(s) received 0.00% packet loss round-trip min/avg/max = 16/59/94 ms
Configuration Files
Device A configuration file
# sysname DeviceA # router id 1.1.1.1 # interface GigabitEthernet0/1/0 undo shutdown ip address 192.168.0.1 255.255.255.0 # interface GigabitEthernet0/1/8 undo shutdown ip address 192.168.1.1 255.255.255.0 # ospf 1 area 0.0.0.0 network 192.168.0.0 0.0.0.255 area 0.0.0.1 network 192.168.1.0 0.0.0.255 # return
Device B configuration file
# sysname DeviceB # router id 2.2.2.2 # interface GigabitEthernet0/1/0 undo shutdown ip address 192.168.0.2 255.255.255.0 # interface GigabitEthernet0/1/8 undo shutdown ip address 192.168.2.1 255.255.255.0 # ospf 1 area 0.0.0.0 network 192.168.0.0 0.0.0.255 area 0.0.0.2 network 192.168.2.0 0.0.0.255 # return
Device C configuration file
# sysname DeviceC # router id 3.3.3.3 # interface GigabitEthernet0/1/0 undo shutdown ip address 192.168.1.2 255.255.255.0 # interface GigabitEthernet0/1/8 undo shutdown ip address 172.16.1.1 255.255.255.0 # ospf 1 area 0.0.0.1 network 192.168.1.0 0.0.0.255 network 172.16.1.0 0.0.0.255 # return
Device D configuration file
# sysname DeviceD # router id 4.4.4.4 # interface GigabitEthernet0/1/0 undo shutdown ip address 192.168.2.2 255.255.255.0 # interface GigabitEthernet0/1/8 undo shutdown ip address 172.17.1.1 255.255.255.0 # ospf 1 area 0.0.0.2 network 192.168.2.0 0.0.0.255 network 172.17.1.0 0.0.0.255 # return
Device E configuration file
# sysname DeviceE # router id 5.5.5.5 # interface GigabitEthernet0/1/8 undo shutdown ip address 172.16.1.2 255.255.255.0 # ospf 1 area 0.0.0.1 network 172.16.1.0 0.0.0.255 # return
Device F configuration file
# sysname DeviceF # router id 6.6.6.6 # interface GigabitEthernet0/1/8 undo shutdown ip address 172.17.1.2 255.255.255.0 # ospf 1 area 0.0.0.2 network 172.17.1.0 0.0.0.255 # return