实验2 配置OSPF DR 选举过程.doc

实验2 配置OSPF DR 选举过程一、 实验拓扑，如图1.1所示图1.1 广播多路访问链路上的OSPF二、 实验配置1. 配置路由器R1R1(config-if)#router os 1R1(config-router)#router-id 1.1.1.1R1(config-router)#net 1.1.1.0 0.0.0.255 a 0R1(config-router)#net 192.168.0.0 0.0.0.255 a 02. 配置路由器R2R2(config)#router ospf 1R2(config-router)#router-id 2.2.2.2R2(config-router)#net 2.2.2.0 0.0.0.255 a 0R2(config-router)#net 192.168.0.0 0.0.0.255 a 03. 配置路由器R3R3(config-if)#router os 1R3(config-router)#router-id 3.3.3.3R3(config-router)#net 3.3.3.0 0.0.0.255 a 0R3(config-router)#net 192.168.0.0 0.0.0.255 a 0三、 实验调试1. 在R1上查看OSPF邻居信息R1(config-router)#do sh ip os neNeighbor ID Pri State Dead Time Address Interface2.2.2.2 1 FULL/DR 00:00:38 192.168.0.2 FastEthernet0/03.3.3.3 1 FULL/DROTHER 00:00:36 192.168.0.3 FastEthernet0/0以上输出说明，R2为DR，R1为BDR，R3为DROTHER。为了防止建立完全的邻接关系而引起大量的开销，在多路访问的网络中需要选举DR和BDR，除自身外，每个路由器均与之建立邻接关系，来同步信息。DR和BDR的组播地址为224.0.0.6选举DR和BDR有一定的顺序，且DR和BDR只具有接口特性：首先启动的路由器将选举为DR，如果同时启动则看接口的优先级，优先级最高的被选举为DR,在BMA网络中，优先级默认为1，如果优先级被设置为0则不参与DR与BDR的选举。如果优先级相同就看router ID，routerID最大的将被选为DR。2. 在三个路由器上同时清OSPF进程，重新选举DR/BDR，验证上述内容。/R1上清OSPF进程R1#clear ip os process Reset ALL OSPF processes? no: yR1#/R2上清OSPF进程R2#clear ip ospf prReset ALL OSPF processes? no: yR2#/R3上清OSPF进程R3#clear ip o pReset ALL OSPF processes? no: yR3#/在R1上查看OSPF邻居信息R1#sh ip os neNeighbor ID Pri State Dead Time Address Interface2.2.2.2 1 FULL/BDR 00:00:34 192.168.0.2 FastEthernet0/03.3.3.3 1 FULL/DR 00:00:36 192.168.0.3 FastEthernet0/0由上可知，在DR/BDR的选举中，遵循“选最大”原则。3. 控制DR/BDR的选举，选择R1为DR，R2为BDR，可以调整各路由器的接口优先级达到所需实验结果/将R1的Fa0/0口接口优先级设为10R1#conf tEnter configuration commands, one per line. End with CNTL/Z.R1(config)#int f0/0R1(config-if)#ip ospf priority 10/将R2的Fa0/0口接口优先级设为5R2#conf tEnter configuration commands, one per line. End with CNTL/Z.R2(config)#int f0/0R2(config-if)#ip ospf priority 5/将R3的Fa0/0口接口优先级设为0，使之不参与选举R3#conf tEnter configuration commands, one per line. End with CNTL/Z.R3(config)#int f0/0R3(config-if)#ip ospf priority 0/在三台路由器上同时清OSPF进程后，在R1上查看OSPF邻居信息R1(config-if)#do sh ip os neNeighbor ID Pri State Dead Time Address Interface2.2.2.2 5 FULL/BDR 00:00:37 192.168.0.2 FastEthernet0/03.3.3.3 0 FULL/DROTHER 00:00:36 192.168.0.3 FastEthernet0/0可以看到，如预先所愿，R1和R2已成功选举成为DR和BDR，R3不参与选举。4. 在R1上查看并解读邻接关系建立的全过程/在R1上开启邻接调试，关闭Fa0/0接口，重新启用R1(config-if)#do deb ip os adjOSPF adjacency events debugging is onR1(config-if)#sh R1(config-if)#no shR1(config-if)#*Aug 2 19:27:01.122: OSPF: Interface FastEthernet0/0 going Up/发送Hello包，建立邻居关系，状态转变为2 Way*Aug 2 19:27:01.286: OSPF: 2 Way Communication to 3.3.3.3 on FastEthernet0/0, state 2WAY*Aug 2 19:27:01.290: OSPF: 2 Way Communication to 2.2.2.2 on FastEthernet0/0, state 2WAY*Aug 2 19:27:01.294: OSPF: Backup seen Event before WAIT timer on FastEthernet0/0/根据Hello信息，选举DR/BDR*Aug 2 19:27:01.294: OSPF: DR/BDR election on FastEthernet0/0 *Aug 2 19:27:01.298: OSPF: Elect BDR 1.1.1.1*Aug 2 19:27:01.298: OSPF: Elect DR 2.2.2.2*Aug 2 19:27:01.298: OSPF: Elect BDR 1.1.1.1*Aug 2 19:27:01.302: OSPF: Elect DR 2.2.2.2*Aug 2 19:27:01.302: DR: 2.2.2.2 (Id) BDR: 1.1.1.1 (Id)/NBR协商，建立主从关系，由master开始交换DBD过程,状态转为EXSTART*Aug 2 19:27:01.302: OSPF: Send DBD to 2.2.2.2 on FastEthernet0/0 seq 0x1734 opt 0x52 flag 0x7 len 32*Aug 2 19:27:01.306: OSPF: Send DBD to 3.3.3.3 on FastEthernet0/0 seq 0x806 opt 0x52 flag 0x7 len 32*Aug 2 19:27:01.338: OSPF: Rcv DBD from 2.2.2.2 on FastEthernet0/0 seq 0x11C5 opt 0x52 flag 0x7 len 32 mtu 1500 state EXSTART*Aug 2 19:27R1(config-if)#:01.342: OSPF: NBR Negotiation Done. We are the SLAVE/双方开始交换DBD，并发送LSAck进行确认，状态转为EXCHANGE*Aug 2 19:27:01.342: OSPF: Send DBD to 2.2.2.2 on FastEthernet0/0 seq 0x11C5 opt 0x52 flag 0x2 len 92*Aug 2 19:27:01.358: OSPF: Rcv DBD from 2.2.2.2 on FastEthernet0/0 seq 0x11C6 opt 0x52 flag 0x3 len 112 mtu 1500 state EXCHANGE*Aug 2 19:27:01.362: OSPF: Send DBD to 2.2.2.2 on FastEthernet0/0 seq 0x11C6 opt 0x52 flag 0x0 len 32*Aug 2 19:27:01.382: OSPF: Rcv DBD from 2.2.2.2 on FastEthernet0/0 seq 0x11C7 opt 0x52 flag 0x1 len 32 mtu 1500 state EXCHANGE/双方发送LSR,向对方请求响应的LSA，回复LSU，状态为Loading*Aug 2 19:27:01.386: OSPF: Exchange Done with 2.2.2.2 on FastEthernet0/0*Aug 2 19:27:01.386: OSPF: Synchronized with 2.2.2.2 on FastEthernet0/0, state FULL/彼此交换完成LSA，同步LSDB，互相发送LSAck确认，进入FULL状态，/确立邻接关系*Aug 2 19:27:01.390: %OSPF-5-ADJCHG: Process 1, Nbr 2.2.2.2 on FastEthernet0/0 from LOADING to FULL, Loading Done整个过程所经历的状