实验24:广播多路访问链路上的OSPF
1.
实验目的
通过本实验可以掌握：
（1）在路由器上启动OSPF 路由进程
（2）启用参与路由协议的接口，并且通告网络及所在的区域
（3）修改参考带宽
（4）DR 选举的控制
（5）广播多路访问链路上的OSPF 的特征
2.
实验拓扑
本实验的拓扑结构如图所示。
3.
实验步骤
注：
（1）为了避免路由器之间建立完全邻接关系而引起的大量开销，OSPF 要求在多路访问
的网络中选举一个DR，每个路由器都与之建立邻接关系。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，而且所有其它路由器只与DR 和BDR 建立邻接关
系；
（2）DR 和BDR 有它们自己的组播地址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，最先启动的路由器被选举成DR；
② 如果同时启动，或者重新选举，则看接口优先级（范围为0-255），优先级最高的被
选举成DR，默认情况下，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”，如果接口的优先级被设置为0，那么该接口将
不参与DR 选举；
③ 如果前两者相同，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，除非人为地重新选举。重新选举DR 的方法有两种，一是路
由器重新启动，二是执行“clear ip ospf process”命令。
（1）步骤1：配置路由器r0
r0(config)#int loo 1
r0(config-if)#ip add 1.1.1
*Mar 1 00:01:29.683: %LINEPROTO-5-UPDOWN: Line protocol on Interface Loopback1, changed state to up
r0(config-if)#ip add 1.1.1.1 255.255.255.0
r0(config-if)#int f0/0
r0(config-if)#ip add 172.16.1.1 255.255.255.0
r0(config-if)#no sh
r0(config-if)#
*Mar 1 00:01:50.631: %LINK-3-UPDOWN: Interface FastEthernet0/0, changed state to up
*Mar 1 00:01:51.631: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed state to up
r0(config-if)#do ping 172.16.1.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.1.2, timeout is 2 seconds:
.!!!!
Success rate is 80 percent (4/5), round-trip min/avg/max = 40/63/92 ms
r0(config-if)#do ping 172.16.1.3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.1.3, timeout is 2 seconds:
.!!!!
Success rate is 80 percent (4/5), round-trip min/avg/max = 48/60/76 ms
r0(config-if)#exit
r0(config)#router ospf 1
r0(config-router)#net 1.1.1.0 0.0.0.255 area 0
r0(config-router)#net 172.16.1.0 0.0.0.255 area 0
r0(config-router)#
*Mar 1 00:05:59.931: %OSPF-5-ADJCHG: Process 1, Nbr 2.2.2.2 on FastEthernet0/0 from LOADING to FULL, Loading Done
r0(config-router)#do ping
*Mar 1 00:06:39.855: %OSPF-5-ADJCHG: Process 1, Nbr 3.3.3.3 on FastEthernet0/0 from LOADING to FULL, Loading Done
r0(config-router)#do ping 3.3.3.3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:
.!!!!
Success rate is 80 percent (4/5), round-trip min/avg/max = 28/46/68 ms
r0(config-router)#do sh ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route
Gateway of last resort is not set
1.0.0.0/24 is subnetted, 1 subnets
C 1.1.1.0 is directly connected, Loopback1
2.0.0.0/32 is subnetted, 1 subnets
O 2.2.2.2 [110/2] via 172.16.1.2, 00:00:06, FastEthernet0/0
3.0.0.0/32 is subnetted, 1 subnets
O 3.3.3.3 [110/2] via 172.16.1.3, 00:00:06, FastEthernet0/0
172.16.0.0/24 is subnetted, 1 subnets
C 172.16.1.0 is directly connected, FastEthernet0/0
r0(config-router)#do sh ip ospf nei
Neighbor ID Pri State Dead Time Address Interface
2.2.2.2 1 FULL/BDR 00:00:31 172.16.1.2 FastEthernet0/0
3.3.3.3 1 FULL/DROTHER 00:00:33 172.16.1.3 FastEthernet0/0
r0(config-router)#do sh ip ospf int
FastEthernet0/0 is up, line protocol is up
Internet Address 172.16.1.1/24, Area 0
//
该接口的地址和运行的OSPF 区域
Process ID 1, Router ID 1.1.1.1, Network Type BROADCAST, Cost: 1
//
进程ID，路由器ID，网络类型，接口Cost 值
Transmit Delay is 1 sec, State DR, Priority 1
//
自己state 是DR
Designated Router (ID) 1.1.1.1, Interface address 172.16.1.1
//DR
的路由器ID 以及接口地址
Backup Designated router (ID) 2.2.2.2, Interface address 172.16.1.2
//BDR
的路由器ID 以及接口地址
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
oob-resync timeout 40
//
显示几个计时器的值
Hello due in 00:00:05
//
距离下次发送Hello 包的时间
Supports Link-local Signaling (LLS)
Index 2/2, flood queue length 0
Next 0x0(0)/0x0(0)
Last flood scan length is 1, maximum is 1
Last flood scan time is 0 msec, maximum is 0 msec
Neighbor Count is 2, Adjacent neighbor count is 2
//
邻居的个数以及已建立邻接关系的邻居的个数
Adjacent with neighbor 2.2.2.2 (Backup Designated Router)
//R2
是BDR
Adjacent with neighbor 3.3.3.3
//
已经建立邻接关系的邻居路由器ID
邻居关系和邻接关系是不能混为一谈的，邻居关
系是指达到2WAY 状态的两台路由器，而邻接关系是指达到FULL 状态的两台路由器。
Suppress hello for 0 neighbor(s)
//
没有进行Hello 抑制
Loopback1 is up, line protocol is up
Internet Address 1.1.1.1/24, Area 0
Process ID 1, Router ID 1.1.1.1, Network Type LOOPBACK, Cost: 1
Loopback interface is treated as a stub Host
r0(config-router)#do debug ip ospf packet
OSPF packet debugging is on
r0(config-router)#
*Mar 1 00:07:49.591: OSPF: rcv. v:2 t:1 l:52 rid:2.2.2.2
aid:0.0.0.0 chk:8666 aut:0 auk: from FastEthernet0/0
r0(config-router)#
*Mar 1 00:07:51.151: OSPF: rcv. v:2 t:1 l:52 rid:3.3.3.3
aid:0.0.0.0 chk:8666 aut:0 auk: from FastEthernet0/0
r0(config-router)#
*Mar 1 00:07:59.591: OSPF: rcv. v:2 t:1 l:52 rid:2.2.2.2
aid:0.0.0.0 chk:8666 aut:0 auk: from FastEthernet0/0
r0(config-router)#
*Mar 1 00:08:01.119: OSPF: rcv. v:2 t:1 l:52 rid:3.3.3.3
aid:0.0.0.0 chk:8666 aut:0 auk: from FastEthernet0/0
r0(config-router)#
*Mar 1 00:08:09.591: OSPF: rcv. v:2 t:1 l:52 rid:2.2.2.2
aid:0.0.0.0 chk:8666 aut:0 auk: from FastEthernet0/0
r0(config-router)#
*Mar 1 00:08:11.119: OSPF: rcv. v:2 t:1 l:52 rid:3.3.3.3
aid:0.0.0.0 chk:8666 aut:0 auk: from FastEthernet0/0
r0(config-router)#
*Mar 1 00:08:19.603: OSPF: rcv. v:2 t:1 l:52 rid:2.2.2.2
aid:0.0.0.0 chk:8666 aut:0 auk: from FastEthernet0/0
r0(config-router)#
*Mar 1 00:08:21.135: OSPF: rcv. v:2 t:1 l:52 rid:3.3.3.3
aid:0.0.0.0 chk:8666 aut:0 auk: from FastEthernet0/0
r0(config-router)#
*Mar 1 00:08:29.603: OSPF: rcv. v:2 t:1 l:52 rid:2.2.2.2
aid:0.0.0.0 chk:8666 aut:0 auk: from FastEthernet0/0
r0(config-router)#
*Mar 1 00:08:31.135: OSPF: rcv. v:2 t:1 l:52 rid:3.3.3.3
aid:0.0.0.0 chk:8666 aut:0 auk: from FastEthernet0/0
r0(config-router)#do un all
All possible debugging has been turned off
r0(config-router)#do debug ip ospf adj
OSPF adjacency events debugging is on
r0(config-router)#clear ip ospf process
^
% Invalid input detected at '^' marker.
r0(config-router)#do clear ip ospf process
Reset ALL OSPF processes? [no]: y
r0(config-router)#
*Mar 1 00:09:08.895: OSPF: Interface FastEthernet0/0 going Down
*Mar 1 00:09:08.895: OSPF: 1.1.1.1 address 172.16.1.1 on FastEthernet0/0 is dead, state DOWN
*Mar 1 00:09:08.895: OSPF: Neighbor change Event on interface FastEthernet0/0
*Mar 1 00:09:08.895: OSPF: DR/BDR election on FastEthernet0/0
*Mar 1 00:09:08.899: OSPF: Elect BDR 2.2.2.2
*Mar 1 00:09:08.899: OSPF: Elect DR 2.2.2.2
*Mar 1 00:09:08.899: OSPF: Elect BDR 2.2.2.2
*Mar 1 00:09:08.899: OSPF: Elect DR 2.2.2.2
*Mar 1 00:09:08.899: DR: 2.2.2.2 (Id) BDR: 2.2.2.2 (Id)
*Mar 1 00:09:08.899: OSPF: Reset adjacency with 3.3.3.3 on FastEthernet0/0, state 2WAY
*Mar 1 00:09:08.899: OSPF: Flush network LSA immediately
*Mar 1 00:09:08.899: OSPF: Remember old DR 1.1.1.1 (id)
*Mar 1 00:09:08.899: OSPF: 2.2.2.2 address 172.16.1.2 on FastEthernet0/0 is dead, state DOWN
*Mar 1 00:09:08.899: %OSPF-5-ADJCHG: Process 1, Nbr 2.2.2.2 on FastEthernet0/0 from FULL to DOWN, Neighbor Down: Interface down or detac
r0(config-router)#hed
*Mar 1 00:09:08.899: OSPF: Neighbor change Event on interface FastEthernet0/0
*Mar 1 00:09:08.899: OSPF: DR/BDR election on FastEthernet0/0
*Mar 1 00:09:08.899: OSPF: Elect BDR 3.3.3.3
*Mar 1 00:09:08.899: OSPF: Elect DR 3.3.3.3
*Mar 1 00:09:08.899: DR: 3.3.3.3 (Id) BDR: 3.3.3.3 (Id)
*Mar 1 00:09:08.899: OSPF: Send DBD to 3.3.3.3 on FastEthernet0/0 seq 0x25C6 opt 0x52 flag 0x7 len 32
*Mar 1 00:09:08.899: OSPF: Remember old DR 2.2.2.2 (id)
*Mar 1 00:09:08.899: OSPF: 3.3.3.3 address 172.16.1.3 on FastEthernet0/0 is dead, state DOWN
*Mar 1 00:09:08.899: %OSPF-5-ADJCHG: Process 1, Nbr 3.3.3.3 on FastEthernet0/0 from EXSTART to DOWN, Neighbor Down: Interface down or detached
*Mar 1 00:09:08.899: OSPF: Neighbor change Event on interface FastEthernet0/0
*Mar 1 00:09:08.899: OSPF: DR/BDR election on FastEthernet0/0
*Mar 1 00:09:08.899: OSPF: Elect BDR 0.0.0.0
*Mar 1 00:09:08.899: OSPF: Elect DR 0.0.0.0
*Mar 1 00:09:08.899: DR: none BDR: non
r0(config-router)#e
*Mar 1 00:09:08.899: OSPF: Remember old DR 3.3.3.3 (id)
*Mar 1 00:09:08.899: OSPF: Interface Loopback1 going Down
*Mar 1 00:09:08.899: OSPF: 1.1.1.1 address 1.1.1.1 on Loopback1 is dead, state DOWN
*Mar 1 00:09:08.915: OSPF: Interface FastEthernet0/0 going Up
*Mar 1 00:09:08.919: OSPF: Interface Loopback1 going Up
*Mar 1 00:09:08.935: %OSPF-4-NONEIGHBOR: Received database description from unknown neighbor 3.3.3.3
*Mar 1 00:09:08.943: OSPF: 2 Way Communication to 3.3.3.3 on FastEthernet0/0, state 2WAY
*Mar 1 00:09:08.947: OSPF: 2 Way Communication to 2.2.2.2 on FastEthernet0/0, state 2WAY
*Mar 1 00:09:09.075: OSPF: Rcv DBD from 2.2.2.2 on FastEthernet0/0 seq 0x276 opt 0x52 flag 0x7 len 32 mtu 1500 state 2WAY
*Mar 1 00:09:09.075: OSPF: Nbr state is 2WAY
*Mar 1 00:09:09.399: OSPF: Build router LSA for area 0, router ID 1.1.1.1, seq 0x80000001
*Mar 1 00:09:09.399: OSPF: We are not DR to build Net Lsa for interface FastEthernet0/0
*Mar 1 00:09:09.631: OSPF: Rc
r0(config-router)#v DBD from 3.3.3.3 on FastEthernet0/0 seq 0x2522 opt 0x52 flag 0x7 len 32 mtu 1500 state 2WAY
*Mar 1 00:09:09.631: OSPF: Nbr state is 2WAY
*Mar 1 00:09:11.115: OSPF: Backup seen Event before WAIT timer on FastEthernet0/0
*Mar 1 00:09:11.115: OSPF: DR/BDR election on FastEthernet0/0
*Mar 1 00:09:11.115: OSPF: Elect BDR 3.3.3.3
*Mar 1 00:09:11.119: OSPF: Elect DR 2.2.2.2
*Mar 1 00:09:11.119: DR: 2.2.2.2 (Id) BDR: 3.3.3.3 (Id)
*Mar 1 00:09:11.119: OSPF: Send DBD to 2.2.2.2 on FastEthernet0/0 seq 0x54 opt 0x52 flag 0x7 len 32
*Mar 1 00:09:11.123: OSPF: Send DBD to 3.3.3.3 on FastEthernet0/0 seq 0x2564 opt 0x52 flag 0x7 len 32
r0(config-router)#
*Mar 1 00:09:14.067: OSPF: Rcv DBD from 2.2.2.2 on FastEthernet0/0 seq 0x276 opt 0x52 flag 0x7 len 32 mtu 1500 state EXSTART
*Mar 1 00:09:14.067: OSPF: NBR Negotiation Done. We are the SLAVE
*Mar 1 00:09:14.071: OSPF: Send DBD to 2.2.2.2 on FastEthernet0/0 seq 0x276 opt 0x52 flag 0x2 len 52
*Mar 1 00:09:14.163: OSPF: Rcv DBD from 2.2.2.2 on FastEthernet0/0 seq 0x277 opt 0x52 flag 0x3 len 92 mtu 1500 state EXCHANGE
*Mar 1 00:09:14.163: OSPF: Send DBD to 2.2.2.2 on FastEthernet0/0 seq 0x277 opt 0x52 flag 0x0 len 32
*Mar 1 00:09:14.255: OSPF: Rcv DBD from 2.2.2.2 on FastEthernet0/0 seq 0x278 opt 0x52 flag 0x1 len 32 mtu 1500 state EXCHANGE
*Mar 1 00:09:14.255: OSPF: Exchange Done with 2.2.2.2 on FastEthernet0/0
*Mar 1 00:09:14.259: OSPF: Send LS REQ to 2.2.2.2 length 36 LSA count 3
*Mar 1 00:09:14.259: OSPF: Send DBD to 2.2.2.2 on FastEthernet0/0 seq 0x278 opt 0x52 flag 0x0 len 32
*Mar 1 00:09:14.287: OSPF: Rcv LS UPD from 2.2.2.2 on FastEthernet0/0 length 156 LSA
r0(config-router)# count 3
*Mar 1 00:09:14.291: OSPF: Synchronized with 2.2.2.2 on FastEthernet0/0, state FULL
*Mar 1 00:09:14.291: %OSPF-5-ADJCHG: Process 1, Nbr 2.2.2.2 on FastEthernet0/0 from LOADING to FULL, Loading Done
*Mar 1 00:09:14.639: OSPF: Rcv DBD from 3.3.3.3 on FastEthernet0/0 seq 0x2522 opt 0x52 flag 0x7 len 32 mtu 1500 state EXSTART
*Mar 1 00:09:14.639: OSPF: NBR Negotiation Done. We are the SLAVE
*Mar 1 00:09:14.643: OSPF: Send DBD to 3.3.3.3 on FastEthernet0/0 seq 0x2522 opt 0x52 flag 0x2 len 112
*Mar 1 00:09:14.711: OSPF: Rcv DBD from 3.3.3.3 on FastEthernet0/0 seq 0x2523 opt 0x52 flag 0x3 len 92 mtu 1500 state EXCHANGE
*Mar 1 00:09:14.711: OSPF: Send DBD to 3.3.3.3 on FastEthernet0/0 seq 0x2523 opt 0x52 flag 0x0 len 32
*Mar 1 00:09:14.743: OSPF: Rcv DBD from 3.3.3.3 on FastEthernet0/0 seq 0x2524 opt 0x52 flag 0x1 len 32 mtu 1500 state EXCHANGE
*Mar 1 00:09:14.743: OSPF: Exchange Done with 3.3.3.3 on FastEthernet0/0
*Mar 1 00:09:14.747: OSPF: Synchronized with
r0(config-router)#3.3.3.3 on FastEthernet0/0, state FULL
*Mar 1 00:09:14.747: %OSPF-5-ADJCHG: Process 1, Nbr 3.3.3.3 on FastEthernet0/0 from LOADING to FULL, Loading Done
*Mar 1 00:09:14.747: OSPF: Send DBD to 3.3.3.3 on FastEthernet0/0 seq 0x2524 opt 0x52 flag 0x0 len 32
*Mar 1 00:09:14.803: OSPF: Rcv LS UPD from 2.2.2.2 on FastEthernet0/0 length 64 LSA count 1
r0(config-router)#
*Mar 1 00:09:16.623: OSPF: Build router LSA for area 0, router ID 1.1.1.1, seq 0x80000002
*Mar 1 00:09:16.711: OSPF: Rcv LS UPD from 2.2.2.2 on FastEthernet0/0 length 76 LSA count 1
*Mar 1 00:09:16.715: OSPF: Rcv LS UPD from 3.3.3.3 on FastEthernet0/0 length 76 LSA count 1
r0(config-router)#
*Mar 1 00:09:18.899: OSPF: Rcv LS UPD from 2.2.2.2 on FastEthernet0/0 length 64 LSA count 1
*Mar 1 00:09:19.555: OSPF: Rcv LS UPD from 3.3.3.3 on FastEthernet0/0 length 64 LSA count 1
r0(config-router)#
*Mar 1 00:09:21.431: OSPF: Rcv LS UPD from 2.2.2.2 on FastEthernet0/0 length 76 LSA count 1
*Mar 1 00:09:21.623: OSPF: Build router LSA for area 0, router ID 1.1.1.1, seq 0x80000004
r0(config-router)#
*Mar 1 00:09:26.663: OSPF: Rcv LS UPD from 2.2.2.2 on FastEthernet0/0 length 76 LSA count 1
r0(config-router)#do un all
All possible debugging has been turned off
r0(config-router)#
① DR 重新选举的过程和结果② 在OSPF 邻接关系建立的过程中，接口的状态的变化包括DOWN、2 Way、EXSTART、
EXCHANGE、Loading 和FULL。
（2）步骤2：配置路由器r1
r1(config)#int loo 1
r1(config-if)#ip add 2.2.2.
*Mar 1 00:03:04.643: %LINEPROTO-5-UPDOWN: Line protocol on Interface Loopback1, changed state to up
r1(config-if)#ip add 2.2.2.2 255.255.255.0
r1(config-if)#int f0/0
r1(config-if)#ip add 172.16.1.2 255.255.255.0
r1(config-if)#no sh
r1(config-if)#
*Mar 1 00:03:24.991: %LINK-3-UPDOWN: Interface FastEthernet0/0, changed state to up
*Mar 1 00:03:25.991: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed state to up
r1(config-if)#exit
r1(config)#router ospf 1
r1(config-router)#net 2.2.2.0 0.0.0.0.255 area 0
^
% Invalid input detected at '^' marker.
r1(config-router)#net 2.2.2.0 0.0.0.255 area 0
r1(config-router)#net 172.16.1.0 0.0.0.255
% Incomplete command.
r1(config-router)#net 172.16.1.0 0.0.0.255 area 0
r1(config-router)#
*Mar 1 00:05:59.455: %OSPF-5-ADJCHG: Process 1, Nbr 1.1.1.1 on FastEthernet0/0 from LOADING to FULL, Loading Done
r1(config-router)#
*Mar 1 00:06:39.343: %OSPF-5-ADJCHG: Process 1, Nbr 3.3.3.3 on FastEthernet0/0 from LOADING to FULL, Loading Done
r1(config-router)#
*Mar 1 00:09:13.843: %OSPF-5-ADJCHG: Process 1, Nbr 1.1.1.1 on FastEthernet0/0 from LOADING to FULL, Loading Done
r1(config-router)#
（3）步骤3：配置路由器r2
r2(config)#int loo 1
r2(config-if)#ip add 17
*Mar 1 00:02:37.347: %LINEPROTO-5-UPDOWN: Line protocol on Interface Loopback1, changed state to up
r2(config-if)#ip add 3.3.3.3 255.255.255.0
r2(config-if)#int f0/0
r2(config-if)#ip add 172.16.1.3 255.255.255.0
r2(config-if)#no sh
r2(config-if)#
*Mar 1 00:03:00.103: %LINK-3-UPDOWN: Interface FastEthernet0/0, changed state to up
*Mar 1 00:03:01.103: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed state to up
r2(config-if)#exit
r2(config)#router ospf 1
r2(config-router)#net 3.3.3.0 0.0.0.255 area 0
r2(config-router)#net 172.16.1.3 0.0.0.255 area 0
r2(config-router)#
*Mar 1 00:06:38.987: %OSPF-5-ADJCHG: Process 1, Nbr 2.2.2.2 on FastEthernet0/0 from LOADING to FULL, Loading Done
*Mar 1 00:06:38.991: %OSPF-5-ADJCHG: Process 1, Nbr 1.1.1.1 on FastEthernet0/0 from LOADING to FULL, Loading Done
r2(config-router)#
*Mar 1 00:09:13.971: %OSPF-5-ADJCHG: Process 1, Nbr 1.1.1.1 on FastEthernet0/0 from LOADING to FULL, Loading Done
r2(config-router)#
本文转自gauyanm 51CTO博客，原文链接：http://blog.51cto.com/gauyanm/237742，如需转载请自行联系原作者
