广播多路访问链路的（OSPF）

时间 2020-06-15

标签广播多路访问链路 ospf 繁體版

原文原文链接

步骤：网络

（1）步骤1：配置路由器R1 ide

R1(config)#router ospf 1 oop

R1(config-router)#router-id 1.1.1 .1 ui

R1(config-router)#network 1.1.1 .1 0.0.0.255 area 0 this

R1(config-router)#network 192.168.1.0 0.0.0 .255 area 0 spa

（2）步骤2：配置路由器R2 debug

R2(config)#router ospf 1 orm

R2(config-router)#router-id 2.2.2 .2 router

R2(config-router)#network 2.2.2 .2 0.0.0.255 area 0 blog

R2(config-router)#network 192.168.1.0 0.0.0 .255 area 0

（3）步骤3：配置路由器R3

R3(config)#router ospf 1

R3(config-router)#router-id 3.3.3 .3

R3(config-router)#network 3.3.3 .3 0.0.0.255 area 0

R3(config-router)#network 192.168.1.0 0.0.0 .255 area 0

（4）步骤4：配置路由器R4

R4(config)#router ospf 1

R4(config-router)#router-id 4.4.4 .4

R4(config-router)#network 4.4.4 .4 0.0.0.255 area 0

R4(config-router)#network 192.168.1.0 0.0.0 .255 area 0

（2）show ip ospf neighbor：查看ospf邻居关系

R1#show ip ospf neighbor

Neighbor ID Pri State Dead Time Address Interface

2.2.2 .2 1 FULL/BDR 00:00:36 192.168.1.2 Ethernet0/0

3.3.3 .3 1 FULL/DROTHER 00:00:39 192.168.1.3 Ethernet0/0

4.4.4 .4 1 FULL/DROTHER 00:00:39 192.168.1.4 Ethernet0/0

以上输出代表在该广播多路访问网络中，R1 是DR,R2 是BDR,R3 和R4 为DROTHER。

【技术要点】

（1）为了不路由器之间创建彻底邻接关系而引发的大量开销，OSPF 要求在多路访问的网络中选举一个DR，每一个路由器都与之创建邻接关系。选举DR 的同时也选举出一个BDR，在DR 失效的时候，BDR 担负起DR 的职责，并且全部其它路由器只与DR 和BDR 创建邻接关系；

（2）DR 和BDR 有它们本身的组播地址224.0.0.6；

（3）DR 和BDR 的选举是以各个网络为基础的，也就是说DR 和BDR 选举是一个路由器的接口特性，而不是整个路由器的特性；

（4）DR 选举的原则：

① 首要因素是时间，最早启动的路由器被选举成DR；

② 若是同时启动，或者从新选举，则看接口优先级（范围为0-255），优先级最高的被选举成DR，默认状况下，多路访问网络的接口优先级为1，点到点网络接口优先级为0，修改接口优先级的命令是“ ip ospf priority”，若是接口的优先级被设置为0，那么该接口将不参与DR 选举；

③ 若是前二者相同，最后看路由器ID，路由器ID 最高的被选举成DR；

（5）DR 选举是非抢占的，除非人为地从新选举。从新选举DR 的方法有两种，一是路由器从新启动，二是执行“clear ip ospf process”命令。

（3）debug ip ospf adj：显示OSPF 邻接关系建立或中断的过程

R2#debug ip ospf adj

OSPF adjacency events debugging is on

R2#clear ip ospf process

Reset ALL OSPF processes? [no]: y

*Mar 1 00:18:23.543: OSPF: Interface Ethernet0/0 going Down

*Mar 1 00:18:23.543: OSPF: 2.2.2 .2 address 192.168.1.2 on Ethernet0/0 is dead,

state DOWN

*Mar 1 00:18:23.543: OSPF: Neighbor change Event on interface Ethernet0/0

*Mar 1 00:18:23.543: OSPF: DR/BDR election on Ethernet0/0

*Mar 1 00:18:23.547: OSPF: Elect BDR 4.4.4 .4

*Mar 1 00:18:23.547: OSPF: Elect DR 1.1.1 .1

*Mar 1 00:18:23.547: OSPF: Elect BDR 4.4.4 .4

*Mar 1 00:18:23.547: OSPF: Elect DR 1.1.1 .1

*Mar 1 00:18:23.547: DR: 1.1.1 .1 (Id) BDR: 4.4.4.4 (Id)

*Mar 1 00:18:23.551: OSPF: Reset adjacency with 3.3.3 .3 on Ethernet0/0, state 2

WAY

*Mar 1 00:18:23.551: OSPF: 1.1.1 .1 address 192.168.1.1 on Ethernet0/0 is dead,

state DOWN

*Mar 1 00:18:23.551: %OSPF-5-ADJCHG: Process 1, Nbr 1.1.1 .1 on Ethernet0/0 from

FULL to DOWN, Neighbor Down: Interface down or detached

*Mar 1 00:18:23.555: OSPF: Neighbor change Event on interface Ethernet0/0

*Mar 1 00:18:23.555: OSPF: DR/BDR election on Ethernet0/0

*Mar 1 00:18:23.555: OSPF: Elect BDR 4.4.4 .4

*Mar 1 00:18:28.803: OSPF: Rcv LS UPD from 1.1.1 .1 on Ethernet0/0 length 76 LSA

count 100:18:23.555: DR: 4.4.4 .4 (Id) BDR: 4.4.4.4 (Id)

*Mar 1 00:18:29.127: OSPF: Rcv LS UPD from 1.1.1 .1 on Ethernet0/0 length 76 LSA

count 100:18:23.559: OSPF: 3.3.3 .3 address 192.168.1.3 on Ethernet0/0 is dead,

*Mar 1 00:18:29.179: OSPF: Rcv LS UPD from 4.4.4 .4 on Ethernet0/0 length 76 LSA

count 100:18:23.559: %OSPF-5-ADJCHG: Process 1, Nbr 3.3.3 .3 on Ethernet0/0 from

*Mar 1 00:18:29.571: OSPF: Build router LSA for area 0, router ID 2.2.2 .2, seq

0x80000004:18:23.559: OSPF: Neighbor change Event on interface Ethernet0/0

*Mar 1 00:18:29.611: OSPF: Rcv LS UPD from 1.1.1 .1 on Ethernet0/0 length 76 LSA

count 100:18:23.563: OSPF: Elect BDR 4.4.4 .4

*Mar 1 00:18:31.475: %CDP-4-DUPLEX_MISMATCH: duplex mismatch discovered on Ethe

rnet0/0 (not full duplex), with Router FastEthernet0/2 (full duplex).

*Mar 1 00:18:23.563: OSPF: 4.4.4 .4 address 192.168.1.4 on Ethernet0/0 is dead,

state DOWN

*Mar 1 00:18:23.567: %OSPF-5-ADJCHG: Process 1, Nbr 4.4.4 .4 on Ethernet0/0 from

FULL to DOWN, Neighbor Down: Interface down or detached

*Mar 1 00:18:23.567: OSPF: Neighbor change Event on interface Ethernet0/0

*Mar 1 00:18:23.567: OSPF: DR/BDR election on Ethernet0/0

*Mar 1 00:18:23.571: OSPF: Elect BDR 0.0.0 .0

*Mar 1 00:18:23.571: OSPF: Elect DR 0.0.0 .0

*Mar 1 00:18:23.571: DR: none BDR: none

*Mar 1 00:18:23.571: OSPF: Remember old DR 4.4.4 .4 (id)

*Mar 1 00:18:23.571: OSPF: Interface Loopback0 going Down

*Mar 1 00:18:23.575: OSPF: 2.2.2 .2 address 2.2.2.2 on Loopback0 is dead, state

DOWN

*Mar 1 00:18:23.655: OSPF: Interface Ethernet0/0 going Up

*Mar 1 00:18:23.655: OSPF: Interface Loopback0 going Up

*Mar 1 00:18:23.675: OSPF: 2 Way Communication to 4.4.4 .4 on Ethernet0/0, state

2WAY

*Mar 1 00:18:23.679: OSPF: Backup seen Event before WAIT timer on Ethernet0/0

*Mar 1 00:18:23.679: OSPF: DR/BDR election on Ethernet0/0

*Mar 1 00:18:23.679: OSPF: Elect BDR 4.4.4 .4

*Mar 1 00:18:23.679: OSPF: Elect DR 4.4.4 .4

*Mar 1 00:18:23.679: DR: 4.4.4 .4 (Id) BDR: 4.4.4.4 (Id)

*Mar 1 00:18:23.683: OSPF: Send DBD to 4.4.4 .4 on Ethernet0/0 seq 0xE02 opt 0x5

2 flag 0x7 len 32

*Mar 1 00:18:23.683: OSPF: 2 Way Communication to 1.1.1 .1 on Ethernet0/0, state

2WAY

*Mar 1 00:18:23.687: OSPF: Neighbor change Event on interface Ethernet0/0

*Mar 1 00:18:23.687: OSPF: DR/BDR election on Ethernet0/0

*Mar 1 00:18:23.687: OSPF: Elect BDR 4.4.4 .4

*Mar 1 00:18:23.687: OSPF: Elect DR 1.1.1 .1

*Mar 1 00:18:23.687: DR: 1.1.1 .1 (Id) BDR: 4.4.4.4 (Id)

*Mar 1 00:18:23.691: OSPF: Send DBD to 1.1.1 .1 on Ethernet0/0 seq 0x 224A opt 0x

52 flag 0x7 len 32

*Mar 1 00:18:23.691: OSPF: Remember old DR 4.4.4 .4 (id)

*Mar 1 00:18:23.691: OSPF: Neighbor change Event on interface Ethernet0/0

*Mar 1 00:18:23.691: OSPF: DR/BDR election on Ethernet0/0

*Mar 1 00:18:23.695: OSPF: Elect BDR 4.4.4 .4

*Mar 1 00:18:23.695: OSPF: Elect DR 1.1.1 .1

*Mar 1 00:18:23.695: DR: 1.1.1 .1 (Id) BDR: 4.4.4.4 (Id)

*Mar 1 00:18:23.695: OSPF: 2 Way Communication to 3.3.3 .3 on Ethernet0/0, state

2WAY

*Mar 1 00:18:23.699: OSPF: Neighbor change Event on interface Ethernet0/0

*Mar 1 00:18:23.699: OSPF: DR/BDR election on Ethernet0/0

*Mar 1 00:18:23.699: OSPF: Elect BDR 4.4.4 .4

*Mar 1 00:18:23.699: OSPF: Elect DR 1.1.1 .1

*Mar 1 00:18:23.699: DR: 1.1.1 .1 (Id) BDR: 4.4.4.4 (Id)

*Mar 1 00:18:23.703: OSPF: Neighbor change Event on interface Ethernet0/0

*Mar 1 00:18:23.703: OSPF: DR/BDR election on Ethernet0/0

*Mar 1 00:18:23.703: OSPF: Elect BDR 4.4.4 .4

*Mar 1 00:18:23.703: OSPF: Elect DR 1.1.1 .1

*Mar 1 00:18:23.703: DR: 1.1.1 .1 (Id) BDR: 4.4.4.4 (Id)

*Mar 1 00:18:23.719: OSPF: Rcv DBD from 4.4.4 .4 on Ethernet0/0 seq 0xD85 opt 0x

以上的输出代表：

① DR 从新选举的过程和结果，新的DR 是R1，BDR 是R4；

② 在OSPF 邻接关系创建的过程当中，接口的状态的变化包括DOWN、2 Way、EXSTART、

EXCHANGE、Loading 和FULL。