cisco 单区域实现OSPFv2
开放最短路径优先（OSPF）协议是一种链路状态路由协议，一般用于同一个路由域内。
- 实现步骤：
- 在接口启用OSPF
- 通配符掩码
- 配置被动接口
- 验证OSPF配置
以下是ospf拓扑
地址分配表
R1配置
R1(config)#router ospf 10 //进程ID
R1(config-router)#rou
R1(config-router)#router-id 1.1.1.1 //路由ID注意：现在只是进入了ospf配置，并没有开启，所以现在要使用network命令来决定那些接口参与ospfv2区域的路由进程
所以我们下一步查看路由表来决定那些接口参与路由进程
R1(config-router)#do show ip rou //在配置模式下查看路由表
Gateway of last resort is not set
172.16.0.0/16 is variably subnetted, 4 subnets, 3 masks
C 172.16.1.0/24 is directly connected, GigabitEthernet0/0
L 172.16.1.1/32 is directly connected, GigabitEthernet0/0
C 172.16.3.0/30 is directly connected, Serial0/0/0
L 172.16.3.1/32 is directly connected, Serial0/0/0
192.168.10.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.10.4/30 is directly connected, Serial0/0/1
L 192.168.10.5/32 is directly connected, Serial0/0/1得知我们要参与路由进程的接口为s0/0/0、s0/0/1
所以到第二步计算通配符掩码
- 通配符掩码位0：匹配地址中对应位的值
- 通配符掩码位1：忽略地址中对应位的值
在通配符掩码中，反码为真
计算通配符掩码最简单的方法就是从255.255.255.255减去网络子网掩码
路由表中s0/0/0接口掩码30位，即255.255.255.252，255.255.255.255减去255.255.255.252结果为0.0.0.3
下一步就是network命令通告网络了
R1(config-router)#network 172.16.1.0 0.0.0.255 area 0 //area跟接入域名
R1(config-router)#network 172.16.3.0 0.0.0.3 area 0
R1(config-router)#network 192.168.10.4 0.0.0.3 area 0由于我们配置的是单域，所以我们配置同一域（0），我这里默认设置为0
最后就是配置被动接口了
启用了ospf的路由，默认情况下都会想所有直连接口发送Hello数据包以此来发现邻居，注意：这时直连接口状态为Init
我们必须知道，在被动接口上无法形成邻居关系的
PC机不需要和路由形成邻居关系，所以配置为被动接口
被动接口会阻止路由信息从指定接口发送出去。但是，从其他接口发出的路由信息仍将通告指定接口所属的网络。
R1(config)#router ospf 10
R1(config-router)#passive-interface g0/0 //配置被动接口g0/0使用show ip protocols检验ospf路由
R1#show ip protocols
Routing Protocol is "ospf 10" //进程id
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Router ID 1.1.1.1 //ospf的id
Number of areas in this router is 1. 1 normal 0 stub 0 nssa
Maximum path: 4
Routing for Networks:
172.16.1.0 0.0.0.255 area 0 //通告网络
172.16.3.0 0.0.0.3 area 0
192.168.10.4 0.0.0.3 area 0
Passive Interface(s):
GigabitEthernet0/1 //被动接口
Routing Information Sources:
Gateway Distance Last Update
1.1.1.1 110 00:22:12 //邻居信息
Distance: (default is 110)
上面只是讲了一下R1单一的配置，R2、R3的脚本如下
R2！！！
R2(config)#router ospf 10
R2(config-router)#router-id 2.2.2.2
R2(config-router)#do show ip rou
Gateway of last resort is not set
172.16.0.0/16 is variably subnetted, 4 subnets, 3 masks
C 172.16.2.0/24 is directly connected, GigabitEthernet0/0
L 172.16.2.1/32 is directly connected, GigabitEthernet0/0
C 172.16.3.0/30 is directly connected, Serial0/0/0
L 172.16.3.2/32 is directly connected, Serial0/0/0
192.168.10.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.10.8/30 is directly connected, Serial0/0/1
L 192.168.10.9/32 is directly connected, Serial0/0/1
R2(config-router)#network 172.16.2.0 0.0.0.255 area 0
R2(config-router)#network 172.16.3.0 0.0.0.3 area 0
R2(config-router)#network 192.168.10.8 0.0.0.3 area 0
R2(config-router)#passive-interface g0/0R3！！！
R3(config)#router ospf 10
R3(config-router)#router-id 3.3.3.3
R3(config-router)#do show ip rou
Gateway of last resort is not set
192.168.1.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.1.0/24 is directly connected, GigabitEthernet0/0
L 192.168.1.1/32 is directly connected, GigabitEthernet0/0
192.168.10.0/24 is variably subnetted, 4 subnets, 2 masks
C 192.168.10.4/30 is directly connected, Serial0/0/0
L 192.168.10.6/32 is directly connected, Serial0/0/0
C 192.168.10.8/30 is directly connected, Serial0/0/1
L 192.168.10.10/32 is directly connected, Serial0/0/1
R3(config-router)#network 192.168.1.0 0.0.0.255 area 0
R3(config-router)#network 192.168.10.4 0.0.0.3 area 0
R3(config-router)#network 192.168.10.8 0.0.0.3 area 0
R3(config-router)#passive-interface g0/0
好啦，本期内容就分享到这里，我们下期见！