配置OSPF

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OSPF概述：

OSPF(Open Shortest Path First开放式最短路径优先）是一个内部网关协议(Interior Gateway Protocol，简称IGP），用于在单一自治系统（autonomous system,AS）内决策路由。是对链路状态路由协议的一种实现，隶属内部网关协议（IGP），故运作于自治系统内部。
Router-ID：
每一台OSPF路由器只有一个Router-ID，Router-ID使用IP地址的形式来表示，确定Router-ID的方法为：
★1 .手工指定Router-ID。
★2 .路由器上活动Loopback接口中IP地址最大的，也就是数字最大的，如C类地址优先于B类地址，一个非活动的接口的IP地址是不能被选为Router-ID的。
★3 .如果没有活动的Loopback接口，则选择活动物理接口IP地址最大的。
注：如果一台路由器收到一条链路状态，无法到达该Router-ID的位置，就无法到达链路状态中的目标网络。
Router-ID只在OSPF启动时计算，或者重置OSPF进程后计算。

使用设备为思科2900，均在模拟环境中完成

R1(config)#interface fastEthernet 0/0
R1(config-if)#ip address 10.1.1.1 255.255.255.252
R1(config-if)#no shutdown
R1(config-if)#exit
R1(config)#interface fastEthernet 1/0
R1(config-if)#ip address 40.4.4.1 255.255.255.252
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 10.1.1.2 255.255.255.252
R2(config-if)#no shutdown
R2(config-if)#exit
R2(config)#interface fastEthernet 1/0
R2(config-if)#ip address 20.2.2.1 255.255.255.252
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 1/0
R3(config-if)#ip address 20.2.2.2 255.255.255.252
R3(config-if)#no shutdown
R3(config-if)#exit
R3(config)#interface fastEthernet 0/0
R3(config-if)#ip address 30.3.3.1 255.255.255.252
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 address 30.3.3.2 255.255.255.252
R4(config-if)#no shutdown
R4(config-if)#exit
R4(config)#interface fastEthernet 1/0
R4(config-if)#ip address 40.4.4.2 255.255.255.252
R4(config-if)#no shutdown
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 10.1.1.1 0.0.0.3 area 0
R1(config-router)#network 40.4.4.1 0.0.0.3 area 0
R1(config-router)#exit
R2(config)#router ospf 1
R2(config-router)#network 2.2.2.2 0.0.0.0 area 0
R2(config-router)#network 20.2.2.1 0.0.0.3 area 0
R2(config-router)#network 10.1.1.2 0.0.0.3 area 0
R2(config-router)#exit
R3(config)#router ospf 1
R3(config-router)#network 3.3.3.3 0.0.0.0 area 0
R3(config-router)#network 30.3.3.1 0.0.0.3 area 0
R3(config-router)#network 20.2.2.2 0.0.0.3 area 0
R3(config-router)#exit
R4(config)#router ospf 1
R4(config-router)#network 4.4.4.4 0.0.0.0 area 0
R4(config-router)#network 30.3.3.2 0.0.0.3 area 0
R4(config-router)#network 40.4.4.2 0.0.0.3 area 0
R4(config-router)#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 10.1.1.2, 00:00:40, FastEthernet0/0
     3.0.0.0/32 is subnetted, 1 subnets
O       3.3.3.3 [110/3] via 40.4.4.2, 00:00:40, FastEthernet1/0
                [110/3] via 10.1.1.2, 00:00:40, FastEthernet0/0
     4.0.0.0/32 is subnetted, 1 subnets
O       4.4.4.4 [110/2] via 40.4.4.2, 00:00:40, FastEthernet1/0
     20.0.0.0/30 is subnetted, 1 subnets
O       20.2.2.0 [110/2] via 10.1.1.2, 00:00:42, FastEthernet0/0
     40.0.0.0/30 is subnetted, 1 subnets
C       40.4.4.0 is directly connected, FastEthernet1/0
     10.0.0.0/30 is subnetted, 1 subnets
C       10.1.1.0 is directly connected, FastEthernet0/0
     30.0.0.0/30 is subnetted, 1 subnets
O       30.3.3.0 [110/2] via 40.4.4.2, 00:00:44, FastEthernet1/0

R1#ping 2.2.2.2

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2.2.2.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 28/36/60 ms
R1#ping 3.3.3.3

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 56/100/144 ms
R1#ping 4.4.4.4

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 4.4.4.4, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 32/48/88 ms

R1#traceroute 3.3.3.3
Type escape sequence to abort.
Tracing the route to 3.3.3.3
  1 40.4.4.2 36 msec
    10.1.1.2 124 msec
    40.4.4.2 32 msec
  2 20.2.2.2 96 msec
    30.3.3.1 64 msec
    20.2.2.2 60 msec

R2(config)#interface fastEthernet 0/0
R2(config-if)#shutdown
R2(config-if)#exit
R1#traceroute 3.3.3.3
Type escape sequence to abort.
Tracing the route to 3.3.3.3
  1 40.4.4.2 76 msec 60 msec 80 msec
  2 30.3.3.1 92 msec 72 msec 60 msec