网络设置如下图所示：

R1(config)#interface fastEthernet 0/0
R1(config-if)#ip address 192.168.1.1 255.255.255.0
R1(config-if)#no shutdown
R1(config-if)#exit
R1(config)#interface loopback 0                      
R1(config-if)#ip address 1.1.1.1 255.255.255.255
R1(config-if)#no shutdown
R1(config-if)#exit
R2(config)#interface fastEthernet 0/0
R2(config-if)#ip address 192.168.1.2 255.255.255.0
R2(config-if)#no shutdown
R2(config-if)#exit
R2(config)#interface loopback 0
R2(config-if)#ip address 2.2.2.2 255.255.255.255
R2(config-if)#no shutdown
R2(config-if)#exit
R3(config)#interface fastEthernet 0/0
R3(config-if)#ip address 192.168.1.3 255.255.255.0
R3(config-if)#no shutdown
R3(config-if)#exit   
R3(config)#interface loopback 0
R3(config-if)#ip address 3.3.3.3 255.255.255.255
R3(config-if)#no shutdown
R3(config-if)#exit
R4(config)#interface fastEthernet 0/0
R4(config-if)#ip add 192.168.1.4 255.255.255.0
R4(config-if)#no shut
R4(config-if)#exit
R4(config)#interface loopback 0
R4(config-if)#ip address 4.4.4.4 255.255.255.255
R4(config-if)#no shutdown
R4(config-if)#exit
R1(config)#router ospf 1
R1(config-router)#network 1.1.1.1 0.0.0.0 area 0
R1(config-router)#network 192.168.1.1 0.0.0.255 area 0
R1(config-router)#exit
R1(config)#interface fastEthernet 0/0
R1(config-if)#ip ospf priority 10
R1(config-if)#no shutdown
R1(config-if)#exit
R2(config)#router ospf 1
R2(config-router)#network 2.2.2.2 0.0.0.0 area 0
R2(config-router)#network 192.168.1.2 0.0.0.255 area 0
R2(config-router)#exit
R2(config)#interface fastEthernet 0/0
R2(config-if)#ip ospf priority 5
R2(config-if)#no shutdown
R2(config-if)#exit
R3(config)#router ospf 1
R3(config-router)#network 3.3.3.3 0.0.0.0 area 0
R3(config-router)#network 192.168.1.3 0.0.0.255 area 0
R3(config-router)#exit
R3(config)#interface fastEthernet 0/0
R3(config-if)#ip ospf priority 0
R3(config-if)#no shutdown
R3(config-if)#exit
R4(config)#router ospf 1
R4(config-router)#network 4.4.4.4 0.0.0.0 area 0
R4(config-router)#network 192.168.1.4 0.0.0.255 area 0
R4(config-router)#exit
R4(config)#interface fastEthernet 0/0
R4(config-if)#ip ospf priority 0
R4(config-if)#no shutdown
R4(config-if)#exit
R1(config)#do show ip route
     1.0.0.0/32 is subnetted, 1 subnets
C       1.1.1.1 is directly connected, Loopback0
     2.0.0.0/32 is subnetted, 1 subnets
O       2.2.2.2 [110/2] via 192.168.1.2, 00:00:51, FastEthernet0/0
     3.0.0.0/32 is subnetted, 1 subnets
O       3.3.3.3 [110/2] via 192.168.1.3, 00:00:51, FastEthernet0/0
     4.0.0.0/32 is subnetted, 1 subnets
O       4.4.4.4 [110/2] via 192.168.1.4, 00:00:51, FastEthernet0/0
C    192.168.1.0/24 is directly connected, FastEthernet0/0

R1#show ip ospf nei
Neighbor ID     Pri   State           Dead Time   Address         Interface
2.2.2.2           5   FULL/BDR        00:00:35    192.168.1.2     FastEthernet0/0
3.3.3.3           0   FULL/DROTHER    00:00:31    192.168.1.3     FastEthernet0/0
4.4.4.4           0   FULL/DROTHER    00:00:39    192.168.1.4     FastEthernet0/0

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指定广播网络中的DR和BDR