本文已参与「新人创作礼」活动，一起开启掘金创作之路。
一、OSPF原理
OSPF是指开放式最短路径优先协议，其具有灵活性好、易于扩展的特性，同时，其具有较高的可靠性。
OSPF的更新为触发更新，其建立路由表的过程如下：
① 建立邻居关系（确认其他路由器是否开启OSPF）
② 泛洪LSA（发送LSA）
③ 收集全网LSA得到LSDB(链路状态数据库)
④ 以自身为根计算最优路径
二、实验拓扑：
三、实验步骤
步骤一：如图配置路由器的IP地址
对R1：
[R1]int lo 0
[R1-LoopBack0]ip address 1.1.1.1 32
[R1-LoopBack0]int g0/0/0
[R1-GigabitEthernet0/0/0]ip address 192.168.1.1 24
对R2：
[R2]int lo0
[R2-LoopBack0]ip address 2.2.2.2 32
[R2-LoopBack0]int g 0/0/0
[R2-GigabitEthernet0/0/0]ip address 192.168.1.2 24
对R3：
[R3]int lo0
[R3-LoopBack0]ip address 3.3.3.3 32
[R3-LoopBack0]int g0/0/0
[R3-GigabitEthernet0/0/0]ip address 192.168.1.3 24
对R4：
[R4]int lo0
[R4-LoopBack0]ip address 4.4.4.4 32
[R4-LoopBack0]int g0/0/0
[R4-GigabitEthernet0/0/0]ip address 192.168.1.4 24
步骤二：进行OSPF配置
对R1：
[R1]ospf 1
[R1-ospf-1]area 0
[R1-ospf-1-area-0.0.0.0]network 1.1.1.1 0.0.0.0
[R1-ospf-1-area-0.0.0.0]network 192.168.1.0 0.0.0.255
对R2：
[R2]ospf
[R2-ospf-1]area 0
[R2-ospf-1-area-0.0.0.0]network 2.2.2.2 0.0.0.0
[R2-ospf-1-area-0.0.0.0]network 192.168.1.0 0.0.0.255
对R3：
[R3]ospf
[R3-ospf-1]area 0
[R3-ospf-1-area-0.0.0.0]network 3.3.3.3 0.0.0.0
[R3-ospf-1-area-0.0.0.0]network 192.168.1.0 0.0.0.255
对R4：
[R4]ospf
[R4-ospf-1]area 0
[R4-ospf-1-area-0.0.0.0]network 4.4.4.4 0.0.0.0
[R4-ospf-1-area-0.0.0.0]network 192.168.1.0 0.0.0.255
四、实验效果及验证
① 查看OSPF邻居关系是否建立
对R1：
[R1]dis ospf peer brief
OSPF Process 1 with Router ID 1.1.1.1
Peer Statistic Information
----------------------------------------------------------------------------
Area Id Interface Neighbor id State
0.0.0.0 GigabitEthernet0/0/0 2.2.2.2 2-Way
0.0.0.0 GigabitEthernet0/0/0 3.3.3.3 Full
0.0.0.0 GigabitEthernet0/0/0 4.4.4.4 Full
----------------------------------------------------------------------------
② 查看路由器之间能否相互ping通（这里以R1为例）
对R1：
[R1]ping 2.2.2.2
PING 2.2.2.2: 56 data bytes, press CTRL_C to break
Reply from 2.2.2.2: bytes=56 Sequence=1 ttl=255 time=60 ms
Reply from 2.2.2.2: bytes=56 Sequence=2 ttl=255 time=50 ms
Reply from 2.2.2.2: bytes=56 Sequence=3 ttl=255 time=40 ms
Reply from 2.2.2.2: bytes=56 Sequence=4 ttl=255 time=60 ms
Reply from 2.2.2.2: bytes=56 Sequence=5 ttl=255 time=40 ms
--- 2.2.2.2 ping statistics ---
5 packet(s) transmitted
5 packet(s) received
0.00% packet loss
round-trip min/avg/max = 40/50/60 ms
[R1]ping 3.3.3.3
PING 3.3.3.3: 56 data bytes, press CTRL_C to break
Reply from 3.3.3.3: bytes=56 Sequence=1 ttl=255 time=70 ms
Reply from 3.3.3.3: bytes=56 Sequence=2 ttl=255 time=40 ms
Reply from 3.3.3.3: bytes=56 Sequence=3 ttl=255 time=50 ms
Reply from 3.3.3.3: bytes=56 Sequence=4 ttl=255 time=40 ms
Reply from 3.3.3.3: bytes=56 Sequence=5 ttl=255 time=40 ms
--- 3.3.3.3 ping statistics ---
5 packet(s) transmitted
5 packet(s) received
0.00% packet loss
round-trip min/avg/max = 40/48/70 ms
[R1]ping 4.4.4.4
PING 4.4.4.4: 56 data bytes, press CTRL_C to break
Reply from 4.4.4.4: bytes=56 Sequence=1 ttl=255 time=60 ms
Reply from 4.4.4.4: bytes=56 Sequence=2 ttl=255 time=50 ms
Reply from 4.4.4.4: bytes=56 Sequence=3 ttl=255 time=50 ms
Reply from 4.4.4.4: bytes=56 Sequence=4 ttl=255 time=60 ms
Reply from 4.4.4.4: bytes=56 Sequence=5 ttl=255 time=60 ms
--- 4.4.4.4 ping statistics ---
5 packet(s) transmitted
5 packet(s) received
0.00% packet loss
round-trip min/avg/max = 50/56/60 ms
路由器之间可以ping通，实验完成。
五、OSPF其他常用配置
① 修改R3 Router-id 为 3.3.3.3
对R3：
[R3]router id 3.3.3.3
② 修改R3 的 dr 优先级为100
[R3]int g 0/0/0
[R3-GigabitEthernet0/0/0]ospf dr-priority 100
③ 修改R3的OSPF的cost值为1000
[R3]interface g0/0/0
[R3-GigabitEthernet0/0/0]ospf cost 1000
④ 修改R3的参考带宽为1000
[R3]ospf
[R3-ospf-1]bandwidth-reference 1000
