320 CHAPTER 28: OSPF CONFIGURATION
DR: 192.168.1.1 BDR: 192.168.1.3 MTU: 0
Dead timer due in 39 sec
Neighbor is up for 00:01:41
Authentication Sequence:[0]
Neighbor state change count: 2
Switch A becomes the DR, and Switch C is the BDR.
n
If the neighbor state is full, it means Switch D has established the adjacency with
the neighbor. If the neighbor state is 2-way, it means the two switches are neither
the DR nor the BDR, and they do not exchange LSAs.
# Display OSPF interface information.
[SwitchA] display ospf interface
OSPF Process 1 with Router ID 1.1.1.1
Interfaces
Area: 0.0.0.0
IP Address Type State Cost Pri DR BDR
192.168.1.1 Broadcast DR 1 100 192.168.1.1 192.168.1.3
[SwitchB] display ospf interface
OSPF Process 1 with Router ID 2.2.2.2
Interfaces
Area: 0.0.0.0
IP Address Type State Cost Pri DR BDR
192.168.1.2 Broadcast DROther 1 0 192.168.1.1 192.168.1.3
n
The interface state DROther means the interface is not the DR/BDR.
Configuring OSPF
Virtual Links
Network requirements
In Figure 97, Area 2 has no direct connection to Area 0, and Area 1 acts as the
Transit Area to connect Area 2 to Area 0 via a configured virtual link between
Switch B and Switch C.
After configuration, Switch A can learn routes to Area 2.
Network diagram
Figure 97 Network diagram for OSPF virtual link configuration
Configuration procedure
1 Configure IP addresses for interfaces (omitted)
2 Configure OSPF basic functions
Area 1
Vlan-int100
192.168.1.2/24
Switch B
Vlan-int200
172.16.1.1/16
Area 2
Vlan-int100
192.168 .1.1/24
Switch A
Area 0
Vlan-int200
10.1.1.1/8
Virtual Link
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