OSPF邻居与邻接关系笔记+实验验证(学习笔记)

ospf邻居邻接关系
原理概述
1.ospf网络中，路由发送的任何链路信息必须建在ospf邻居邻接关系之上
2.hello报文：
1）Router-ID
2）Area-ID
3）认证信息
4）网络掩码
5）Hello时间间隔
2.ospf路由器建立邻居关系建立完成之后，下一步才是建立邻接关系；
3.并不是所有ospf邻居之间都可以建立邻接关系，这取决于ospf邻居之间的网络类型；点到点网络可之间建立邻接关系；在广播型网络上，会选举DR和BDR，DR和BDR会与所有其他路由器建立邻接关系，其他路由器都只与DR和BDR建立邻接关系。

实验验证

拓扑

---

1.配置接口（略）

2.配置ospf路由协议

1）配置R1

[R1]ospf router-id 10.0.1.1

[R1-ospf-1]area 0
[R1-ospf-1-area-0.0.0.0]network 10.0.1.1 0.0.0.0
[R1-ospf-1-area-0.0.0.0]network 10.0.123.0 0.0.0.255
[R1-ospf-1-area-0.0.0.0]q
[R1-ospf-1]area 1
[R1-ospf-1-area-0.0.0.1]network 10.0.14.0 0.0.0.255
[R1-ospf-1-area-0.0.0.1]q
[R1-ospf-1]area 2
[R1-ospf-1-area-0.0.0.2]network 10.0.15.0 0.0.0.255

[R1-ospf-1]dis this 
[V200R003C00]
#
ospf 1 router-id 10.0.1.1 
 area 0.0.0.0 
  network 10.0.1.1 0.0.0.0 
  network 10.0.123.0 0.0.0.255 
 area 0.0.0.1 
  network 10.0.14.0 0.0.0.255 
 area 0.0.0.2 
  network 10.0.15.0 0.0.0.255 
#
return

2）配置R2

[R2]ospf router-id 10.0.2.2
[R2-ospf-1]area 0
[R2-ospf-1]dis this 
[V200R003C00]
#
ospf 1 router-id 10.0.2.2 
 area 0.0.0.0 
  network 10.0.2.2 0.0.0.0 
  network 10.0.123.0 0.0.0.255 
#
return

3）配置R3

[R3]ospf router-id 10.0.3.3
[R3-ospf-1]area 0
[R3-ospf-1]dis this 
[V200R003C00]
#
ospf 1 router-id 10.0.3.3 
 area 0.0.0.0 
  network 10.0.3.3 0.0.0.0 
  network 10.0.123.0 0.0.0.255 
#
return

4）配置R4

[R4]ospf router-id 10.0.4.4
[R4-ospf-1]area 1
[R4-ospf-1]dis this 
[V200R003C00]
#
ospf 1 router-id 10.0.4.4 
 area 0.0.0.1 
  network 10.0.4.4 0.0.0.0 
  network 10.0.14.0 0.0.0.255 
#
return

5）配置R5

[R5]ospf router-id 10.0.5.5 
[R5-ospf-1]area 2
[R5-ospf-1]dis this 
[V200R003C00]
#
ospf 1 router-id 10.0.5.5 
 area 0.0.0.2 
  network 10.0.5.5 0.0.0.0 
  network 10.0.15.0 0.0.0.255 
#
return

6）查看邻居关系

dis ospf peer brief

	 OSPF Process 1 with Router ID 10.0.1.1
		  Peer Statistic Information
 ----------------------------------------------------------------------------
 Area Id          Interface                        Neighbor id      State    
 0.0.0.0          GigabitEthernet0/0/0             10.0.2.2         Full        
 0.0.0.0          GigabitEthernet0/0/0             10.0.3.3         Full        
 0.0.0.1          Serial1/0/0                      10.0.4.4         Full        
 0.0.0.2          Serial1/0/1                      10.0.5.5         Full        
 ----------------------------------------------------------------------------
 Full表示邻居邻接关系建立成功

7）邻居状态详细信息

dis ospf peer 

	 OSPF Process 1 with Router ID 10.0.1.1
		 Neighbors 

 Area 0.0.0.0 interface 10.0.123.1(GigabitEthernet0/0/0)'s neighbors
 Router ID: 10.0.2.2         Address: 10.0.123.2      
   State: Full  Mode:Nbr is  Master  Priority: 1
   DR: 10.0.123.3  BDR: 10.0.123.1  MTU: 0    
   Dead timer due in 37  sec 
   Retrans timer interval: 5 
   Neighbor is up for 00:02:56     
   Authentication Sequence: [ 0 ] 

 Router ID: 10.0.3.3         Address: 10.0.123.3      
   State: Full  Mode:Nbr is  Master  Priority: 1
   DR: 10.0.123.3  BDR: 10.0.123.1  MTU: 0    
   Dead timer due in 33  sec 
   Retrans timer interval: 5 
   Neighbor is up for 00:03:28     
   Authentication Sequence: [ 0 ] 

		 Neighbors 

 Area 0.0.0.1 interface 10.0.14.1(Serial1/0/0)'s neighbors
 Router ID: 10.0.4.4         Address: 10.0.14.4       
   State: Full  Mode:Nbr is  Master  Priority: 1
   DR: None   BDR: None   MTU: 0    
   Dead timer due in 36  sec 
   Retrans timer interval: 5 
   Neighbor is up for 00:02:51     
   Authentication Sequence: [ 0 ] 

		 Neighbors 

 Area 0.0.0.2 interface 10.0.15.1(Serial1/0/1)'s neighbors
 Router ID: 10.0.5.5         Address: 10.0.15.5       
   State: Full  Mode:Nbr is  Master  Priority: 1
   DR: None   BDR: None   MTU: 0    
   Dead timer due in 40  sec 
   Retrans timer interval: 5 
   Neighbor is up for 00:02:57     
   Authentication Sequence: [ 0 ] 

可以看到，R1,R2,R3的广播网络完成了DR和BDR的选举，R3为DR，R2为BDR；R1和R4，R1和R5没有选举DR和BDR是因为他们是点到点网络

3.观察OSPF邻居邻接关系的建立过程

通过命令
debugging ospf packaget
reset ospf process 
可以看到过程

4.观察DRothers只会建立邻居关系

（现在R3 为DR，R1为BDR ;将R1的G0/0/0和R2 的G0/0/0优先级改为0 进行观察）

[R1-GigabitEthernet0/0/0]ospf dr-priority 0
[R2-GigabitEthernet0/0/0]ospf dr-priority 0

R3与R1和R2建立了邻接

R1与DRother路由R2建立了邻居关系


可以看出R1与R3 为邻接full状态，与R2 为邻居状态2-way

5.观察点到点网络中OSPF邻居关系建立情况

[R1]int s1/0/0
[R1-Serial1/0/0]undo shutdown 
[R1-Serial1/0/0]int s1/0/1
[R1-Serial1/0/1]undo shutdown 
[R1]int g0/0/0
[R1-GigabitEthernet0/0/0]shutdown 

可以看到R1与R4和R5建立了邻接关系
dis ospf peer brief 

	 OSPF Process 1 with Router ID 10.0.1.1
		  Peer Statistic Information
 ----------------------------------------------------------------------------
 Area Id          Interface                        Neighbor id      State    
 0.0.0.1          Serial1/0/0                      10.0.4.4         Full        
 0.0.0.2          Serial1/0/1                      10.0.5.5         Full        
 ----------------------------------------------------------------------------
 重启OSPF进行观察状态
 Down->init->Exstart->Exchange->Loading->full

得出结论：点到点网络里面，能够建立OSPF邻居关系的路由器一定会继续建立邻接关系

6.观察OSPF链路状态数据库的同步过程

在R１　S１／０／０接口抓包
重启OSPF进程

debugging ospf packet 
reset ospf process 

在第一次交互报文时可以看到I,M,MS都为1.R1和R4都宣称自己为主路由器.