动态路由——OSPF(开放式最短路径优先协议)简介
一.OSPF协议原理简介
二.OSPF协议特点
三.OSPF区域
1.OSPF区域划分作用
2.OSPF 区域划分方式：基于接口(链路)划分区域
3.OSPF 区域标识： 最终归结为32个二进制
4.区域分类： 便于区域设计
5.OSPF 路由器角色：
四.OSPF简单配置
1.路由配置
2.缺省路由配置
一.OSPF协议原理简介
路由器向邻居发送报文，报文中包含自己所知道的路由信息，与邻居形成邻居表，后路由器之间发送链路状态通告告知邻居自己的链路连接状态，形成LSDB拓扑表，后形成路由表。
二.OSPF协议特点
1.协议范围是IGP内部网关协议，协议算法采用链路状态型路由协议，传递网络掩码(无类别的路由协议) ，基于IP协议封装，IP层协议号为89。
2.OSPF是一种链路状态型协议（既传递路由信息也传递拓扑信息），传递的是 LSA (链路状态通告 共6种类型LSA1 2 3 4 5 7) 。
3.OSPF 更新方式： 触发更新 + 30分钟的周期链路状态刷新 。触发更新—网络结构稳定的时候不发数据，网络结构产生变化（网段数量或信息变化，接口状态变化等）时发数据，OSPF 更新地址： 224.0.0.5/6
4.OSPF 支持区域划分，比较消耗路由器资源。
5.开销值计算方式为100Mbps（参照带宽）/真实带宽，若产生小数点直接舍弃
三.OSPF区域
1.OSPF区域划分作用
限制LSA的传播范围
减少LSA的数量
2.OSPF 区域划分方式：基于接口(链路)划分区域
3.OSPF 区域标识： 最终归结为32个二进制
十进制数或者类似于IP地址形式
4.区域分类： 便于区域设计
骨干区域(0区域)
非骨干区域 (非0区域)
区域设计原则：
OSPF网络中必须存在并且唯一的骨干区域(单区域可以不为骨干区域 )
有非骨干区域时，非骨干区域必须与骨干区域直接相连
5.OSPF 路由器角色：
骨干路由器：路由器所有接口都属于骨干区域
非骨干路由器：路由器接口都不属于骨干区域
ABR：区域边界路由器，骨干区域和非骨干区域的接界
ASBR：自治系统边界路由器，位于使用不同协议的路由器边界上，将路由引入为对方能够学习成功的路由
四.OSPF简单配置
[r1]display ip interface brief
Interface IP Address/Mask Physical Protocol
GigabitEthernet0/0/0 10.1.1.1/24 up up
LoopBack0 1.1.1.1/24 up up(s)
[r2]display ip interface brief
Interface IP Address/Mask Physical Protocol
GigabitEthernet0/0/0 20.1.1.1/24 up up
GigabitEthernet0/0/1 10.1.1.2/24 up up
LoopBack0 2.2.2.2/24 up up(s)
[r3]display ip interface brief
Interface IP Address/Mask Physical Protocol
GigabitEthernet0/0/1 20.1.1.2/24 up up
LoopBack0 3.3.3.3/24 up up(s) 1.路由配置
（1）启用ospf指定进程号（和rip协议相同，进程号只具有本地意义），指定router id(路由标识符)，必须书写，代表着该设备在ospf网络中的唯一性，有两种方式——手工指定，这是最简易的也是最优先的；自动选取环回接口/物理接口最大的作为标识
[r1]ospf 100 router-id 91.1.1.1
[r2]ospf 100 router-id 92.1.1.1
[r3]ospf 100 router-id 93.1.1.1（2）进入ospf区域（以全区域为例）
[r1-ospf-100]area 0
[r1-ospf-100-area-0.0.0.0]
[r2-ospf-100]area 0
[r2-ospf-100-area-0.0.0.0]
[r3-ospf-100]area 0
[r3-ospf-100-area-0.0.0.0]（3）network通告，使用反掩码，实现精确通告，连续的0和连续的1组成，0代表固定位，1代表可变位，仅告知是否可变，不告知网络/主机位
[r1-ospf-100-area-0.0.0.0]network 1.1.1.1 0.0.0.0
[r1-ospf-100-area-0.0.0.0]network 10.1.1.1 0.0.0.0
[r2-ospf-100-area-0.0.0.0]network 2.2.2.2 0.0.0.0
[r2-ospf-100-area-0.0.0.0]network 10.1.1.2 0.0.0.0
[r2-ospf-100-area-0.0.0.0]network 20.1.1.1 0.0.0.0
[r3-ospf-100-area-0.0.0.0]network 3.3.3.3 0.0.0.0
[r3-ospf-100-area-0.0.0.0]network 20.1.1.2 0.0.0.0（4）查表
邻居表
[r1-ospf-100-area-0.0.0.0]display ospf peer brief
OSPF Process 100 with Router ID 91.1.1.1
Peer Statistic Information
----------------------------------------------------------------------------
Area Id Interface Neighbor id State
0.0.0.0 GigabitEthernet0/0/0 92.1.1.1 Full
----------------------------------------------------------------------------
[r2-ospf-100-area-0.0.0.0]display ospf peer brief
OSPF Process 100 with Router ID 92.1.1.1
Peer Statistic Information
----------------------------------------------------------------------------
Area Id Interface Neighbor id State
0.0.0.0 GigabitEthernet0/0/1 91.1.1.1 Full
0.0.0.0 GigabitEthernet0/0/0 93.1.1.1 Full
----------------------------------------------------------------------------
[r3-ospf-100-area-0.0.0.0]display ospf peer brief
OSPF Process 100 with Router ID 93.1.1.1
Peer Statistic Information
----------------------------------------------------------------------------
Area Id Interface Neighbor id State
0.0.0.0 GigabitEthernet0/0/1 92.1.1.1 Full
----------------------------------------------------------------------------LSDB表
[r1-ospf-100-area-0.0.0.0]display ospf lsdb
OSPF Process 100 with Router ID 91.1.1.1
Link State Database
Area: 0.0.0.0
Type LinkState ID AdvRouter Age Len Sequence Metric
Router 93.1.1.1 93.1.1.1 284 48 80000005 1
Router 92.1.1.1 92.1.1.1 292 60 80000009 1
Router 91.1.1.1 91.1.1.1 428 48 80000005 1
Network 10.1.1.2 92.1.1.1 422 32 80000002 0
Network 20.1.1.2 93.1.1.1 284 32 80000002 0
[r2-ospf-100-area-0.0.0.0]display ospf lsdb
OSPF Process 100 with Router ID 92.1.1.1
Link State Database
Area: 0.0.0.0
Type LinkState ID AdvRouter Age Len Sequence Metric
Router 93.1.1.1 93.1.1.1 302 48 80000005 1
Router 92.1.1.1 92.1.1.1 310 60 80000009 1
Router 91.1.1.1 91.1.1.1 448 48 80000005 1
Network 10.1.1.2 92.1.1.1 440 32 80000002 0
Network 20.1.1.2 93.1.1.1 302 32 80000002 0
[r3-ospf-100-area-0.0.0.0]display ospf lsdb
OSPF Process 100 with Router ID 93.1.1.1
Link State Database
Area: 0.0.0.0
Type LinkState ID AdvRouter Age Len Sequence Metric
Router 93.1.1.1 93.1.1.1 317 48 80000005 1
Router 92.1.1.1 92.1.1.1 327 60 80000009 1
Router 91.1.1.1 91.1.1.1 465 48 80000005 1
Network 10.1.1.2 92.1.1.1 457 32 80000002 0
Network 20.1.1.2 93.1.1.1 317 32 80000002 0
路由表
[r1-ospf-100-area-0.0.0.0]display ip routing-table protocol ospf
Route Flags: R - relay, D - download to fib
------------------------------------------------------------------------------
Public routing table : OSPF
Destinations : 3 Routes : 3
OSPF routing table status :
Destinations : 3 Routes : 3
Destination/Mask Proto Pre Cost Flags NextHop Interface
2.2.2.2/32 OSPF 10 1 D 10.1.1.2 GigabitEthernet
0/0/0
3.3.3.3/32 OSPF 10 2 D 10.1.1.2 GigabitEthernet
0/0/0
20.1.1.0/24 OSPF 10 2 D 10.1.1.2 GigabitEthernet
0/0/0
OSPF routing table status :
Destinations : 0 Routes : 0
[r2-ospf-100-area-0.0.0.0]display ip routing-table protocol ospf
Route Flags: R - relay, D - download to fib
------------------------------------------------------------------------------
Public routing table : OSPF
Destinations : 2 Routes : 2
OSPF routing table status :
Destinations : 2 Routes : 2
Destination/Mask Proto Pre Cost Flags NextHop Interface
1.1.1.1/32 OSPF 10 1 D 10.1.1.1 GigabitEthernet
0/0/1
3.3.3.3/32 OSPF 10 1 D 20.1.1.2 GigabitEthernet
0/0/0
OSPF routing table status :
Destinations : 0 Routes : 0
[r3-ospf-100-area-0.0.0.0]display ip routing-table protocol ospf
Route Flags: R - relay, D - download to fib
------------------------------------------------------------------------------
Public routing table : OSPF
Destinations : 3 Routes : 3
OSPF routing table status :
Destinations : 3 Routes : 3
Destination/Mask Proto Pre Cost Flags NextHop Interface
1.1.1.1/32 OSPF 10 2 D 20.1.1.1 GigabitEthernet
0/0/1
2.2.2.2/32 OSPF 10 1 D 20.1.1.1 GigabitEthernet
0/0/1
10.1.1.0/24 OSPF 10 2 D 20.1.1.1 GigabitEthernet
0/0/1
OSPF routing table status :
Destinations : 0 Routes : 0 可以注意到表内环回接口掩码被标注为32位，表示一条主机路由，固定为一个主机，是由于OSPF测试到你是一个环回接口，默认给你识别为32位。进入环回更改network类型即可还原真实网络掩码。
[r1]interface LoopBack 0
[r1-LoopBack0]ospf network-type broadcast
[r2]interface LoopBack 0
[r2-LoopBack0]ospf network-type broadcast
[r3]interface LoopBack 0
[r3-LoopBack0]ospf network-type broadcast
[r1]display ip routing-table protocol ospf
Route Flags: R - relay, D - download to fib
------------------------------------------------------------------------------
Public routing table : OSPF
Destinations : 3 Routes : 3
OSPF routing table status :
Destinations : 3 Routes : 3
Destination/Mask Proto Pre Cost Flags NextHop Interface
2.2.2.0/24 OSPF 10 1 D 10.1.1.2 GigabitEthernet
0/0/0
3.3.3.0/24 OSPF 10 2 D 10.1.1.2 GigabitEthernet
0/0/0
20.1.1.0/24 OSPF 10 2 D 10.1.1.2 GigabitEthernet
0/0/0
OSPF routing table status :
Destinations : 0 Routes : 0
[r2]display ip routing-table protocol ospf
Route Flags: R - relay, D - download to fib
------------------------------------------------------------------------------
Public routing table : OSPF
Destinations : 2 Routes : 2
OSPF routing table status :
Destinations : 2 Routes : 2
Destination/Mask Proto Pre Cost Flags NextHop Interface
1.1.1.0/24 OSPF 10 1 D 10.1.1.1 GigabitEthernet
0/0/1
3.3.3.0/24 OSPF 10 1 D 20.1.1.2 GigabitEthernet
0/0/0
OSPF routing table status :
Destinations : 0 Routes : 0
[r3]display ip routing-table protocol ospf
Route Flags: R - relay, D - download to fib
------------------------------------------------------------------------------
Public routing table : OSPF
Destinations : 3 Routes : 3
OSPF routing table status :
Destinations : 3 Routes : 3
Destination/Mask Proto Pre Cost Flags NextHop Interface
1.1.1.0/24 OSPF 10 2 D 20.1.1.1 GigabitEthernet
0/0/1
2.2.2.0/24 OSPF 10 1 D 20.1.1.1 GigabitEthernet
0/0/1
10.1.1.0/24 OSPF 10 2 D 20.1.1.1 GigabitEthernet
0/0/1
OSPF routing table status :
Destinations : 0 Routes : 0 2.缺省路由配置
在边界路由器上新建一个环回接口，此时其他路由器不能到达
（1）强制产生
进入ospf进行配置强制产生
[r1]ospf 100
[r1-ospf-100]default-route-advertise always
[r2]display ip routing-table protocol ospf
Route Flags: R - relay, D - download to fib
------------------------------------------------------------------------------
Public routing table : OSPF
Destinations : 3 Routes : 3
OSPF routing table status :
Destinations : 3 Routes : 3
Destination/Mask Proto Pre Cost Flags NextHop Interface
0.0.0.0/0 O_ASE 150 1 D 10.1.1.1 GigabitEthernet
0/0/1
1.1.1.0/24 OSPF 10 1 D 10.1.1.1 GigabitEthernet
0/0/1
3.3.3.0/24 OSPF 10 1 D 20.1.1.2 GigabitEthernet
0/0/0
OSPF routing table status :
Destinations : 0 Routes : 0
[r2]ping 6.6.6.6
PING 6.6.6.6: 56 data bytes, press CTRL_C to break
Reply from 6.6.6.6: bytes=56 Sequence=1 ttl=255 time=20 ms
Reply from 6.6.6.6: bytes=56 Sequence=2 ttl=255 time=20 ms
Reply from 6.6.6.6: bytes=56 Sequence=3 ttl=255 time=30 ms
Reply from 6.6.6.6: bytes=56 Sequence=4 ttl=255 time=20 ms
Reply from 6.6.6.6: bytes=56 Sequence=5 ttl=255 time=20 ms
--- 6.6.6.6 ping statistics ---
5 packet(s) transmitted
5 packet(s) received
0.00% packet loss
round-trip min/avg/max = 20/22/30 ms
[r3]ping 6.6.6.6
PING 6.6.6.6: 56 data bytes, press CTRL_C to break
Reply from 6.6.6.6: bytes=56 Sequence=1 ttl=254 time=40 ms
Reply from 6.6.6.6: bytes=56 Sequence=2 ttl=254 time=20 ms
Reply from 6.6.6.6: bytes=56 Sequence=3 ttl=254 time=30 ms
Reply from 6.6.6.6: bytes=56 Sequence=4 ttl=254 time=20 ms
Reply from 6.6.6.6: bytes=56 Sequence=5 ttl=254 time=20 ms
--- 6.6.6.6 ping statistics ---
5 packet(s) transmitted
5 packet(s) received
0.00% packet loss
round-trip min/avg/max = 20/26/40 ms （2）新建或已存在其它类型的缺省
进入ospf进行配置
[r1]display ip interface brief
Interface IP Address/Mask Physical Protocol
GigabitEthernet0/0/0 10.1.1.1/24 up up
GigabitEthernet0/0/1 unassigned down down
GigabitEthernet0/0/2 unassigned down down
LoopBack0 1.1.1.1/24 up up(s)
LoopBack1 6.6.6.6/24 up up(s)
NULL0 unassigned up up(s)
[r1]ospf 100
[r1-ospf-100]default-route-advertise
[r1]ip route-static 0.0.0.0 0.0.0.0 LoopBack 1
[r1]display ip routing-table protocol static
Route Flags: R - relay, D - download to fib
------------------------------------------------------------------------------
Public routing table : Static
Destinations : 1 Routes : 1 Configured Routes : 1
Static routing table status :
Destinations : 1 Routes : 1
Destination/Mask Proto Pre Cost Flags NextHop Interface
0.0.0.0/0 Static 60 0 D 6.6.6.6 LoopBack1
Static routing table status :
Destinations : 0 Routes : 0
[r2]ping 6.6.6.6
PING 6.6.6.6: 56 data bytes, press CTRL_C to break
Reply from 6.6.6.6: bytes=56 Sequence=1 ttl=255 time=30 ms
Reply from 6.6.6.6: bytes=56 Sequence=2 ttl=255 time=20 ms
Reply from 6.6.6.6: bytes=56 Sequence=3 ttl=255 time=30 ms
Reply from 6.6.6.6: bytes=56 Sequence=4 ttl=255 time=20 ms
Reply from 6.6.6.6: bytes=56 Sequence=5 ttl=255 time=20 ms
--- 6.6.6.6 ping statistics ---
5 packet(s) transmitted
5 packet(s) received
0.00% packet loss
round-trip min/avg/max = 20/24/30 ms
[r3]ping 6.6.6.6
PING 6.6.6.6: 56 data bytes, press CTRL_C to break
Reply from 6.6.6.6: bytes=56 Sequence=1 ttl=254 time=40 ms
Reply from 6.6.6.6: bytes=56 Sequence=2 ttl=254 time=30 ms
Reply from 6.6.6.6: bytes=56 Sequence=3 ttl=254 time=30 ms
Reply from 6.6.6.6: bytes=56 Sequence=4 ttl=254 time=20 ms
Reply from 6.6.6.6: bytes=56 Sequence=5 ttl=254 time=30 ms
--- 6.6.6.6 ping statistics ---
5 packet(s) transmitted
5 packet(s) received
0.00% packet loss
round-trip min/avg/max = 20/30/40 ms