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至顶网网络频道路由交换OSPF实验1:基本的OSPF配置

OSPF实验1:基本的OSPF配置

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路由器的RID是路由器接口的最高的IP地址,当有环回口存在是,路由器将使用环回口的最高IP地址作为起RID,从而保证RID的稳定。

来源:chinaitlab 2010年3月27日

关键字: OSPF 路由协议

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  实验步骤:

  1.首先在3台路由器上配置物理接口,并且使用ping命令确保物理链路的畅通。

  2.在路由器上配置loopback接口:

  R1(config)#int loopback 0

  R1(config-if)#ip add 1.1.1.1 255.255.255.0

  R2(config)#int loopback 0

  R2(config-if)#ip add 2.2.2.2 255.255.255.0

  R3(config)#int loopback 0

  R3(config-if)#ip add 3.3.3.3 255.255.255.0

  路由器的RID是路由器接口的最高的IP地址,当有环回口存在是,路由器将使用环回口的最高IP地址作为起RID,从而保证RID的稳定。

  3. 在3台路由器上分别启动ospf进程,并且宣告直连接口的网络。

  R1(config)#router ospf 10

  R1(config-router)#network 192.168.1.0 0.0.0.255 area 0

  R1(config-router)#network 1.1.1.0 0.0.0.255 area 0

  R1(config-router)#network 192.168.3.0.0.0.255 area 0

  ospf的进程号只有本地意义,既在不同路由器上的进程号可以不相同。但是为了日后维护的方便,一般启用相同的进程号。

  ospf使用反向掩码。Area 0表示骨干区域,在设计ospf网络时,所有的非骨干区域都需要和骨干区域直连!

  R2,R3的配置和R1类似,这里省略。不同的是我们在R2和R3上不宣告各自的环回口。

  *Aug 13 17:58:51.411: %OSPF-5-ADJCHG: Process 10, Nbr 2.2.2.2 on Serial1/0 from LOADING to FULL, Loading Done

  配置结束后,我们可以看到邻居关系已经到达FULL状态。

  4. 在R1上查看路由表,可以看到以下信息:

  R1#show 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, Loopback0

  C 192.168.1.0/24 is directly connected, Serial1/0

  O 192.168.2.0/24 [110/65] via 192.168.1.2, 00:03:42, Serial1/0

  C 192.168.3.0/24 is directly connected, FastEthernet0/

  我们看到R1学到了192.168.2.0/24这个网段的路由。后面的数字[110/65],分别表示OSPF的管理距离(AD)和路由的Metric值

  OSPF的Metric值是由cost值逐跳累加的。Cost=100Mb/带宽值。

  5. 在R1上show ip ospf neighbor 、show ip ospf interface

  R1#show ip ospf neighbor

  Neighbor ID Pri State Dead Time Address Interface

  3.3.3.3 1 FULL/BDR 00:00:34 192.168.3.3 FastEthernet0/0

  2.2.2.2 0 FULL/ - 00:00:32 192.168.1.2 Serial1/0

  我们看到R1和R3选取了DR和BDR,而R1和R2没有选取。

  在ospf的五种网络类型中。Point-to-Point,Point-to-Multipoint(广播与非广播)这三种网络类型不选取DR与BDR; Broadcast,NBMA选取DR与BDR。

  R1#show ip ospf interface

  FastEthernet0/0 is up, line protocol is up

  Internet Address 192.168.3.1/24, Area 0

  Process ID 10, Router ID 1.1.1.1, Network Type BROADCAST, Cost: 1

  Transmit Delay is 1 sec, State DR, Priority 1

  Designated Router (ID) 1.1.1.1, Interface address 192.168.3.1

  Backup Designated router (ID) 3.3.3.3, Interface address 192.168.3.3

  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5

  oob-resync timeout 40

  Hello due in 00:00:03

  Index 3/3, 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 1, Adjacent neighbor count is 1

  Adjacent with neighbor 3.3.3.3 (Backup Designated Router)

  Suppress hello for 0 neighbor(s)

  Serial1/0 is up, line protocol is up

  Internet Address 192.168.1.1/24, Area 0

  Process ID 10, Router ID 1.1.1.1, Network Type POINT_TO_POINT, Cost: 64

  Transmit Delay is 1 sec, State POINT_TO_POINT,

  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5

  oob-resync timeout 40

  Hello due in 00:00:02

  Index 1/1, flood queue length 0

  Next 0x0(0)/0x0(0)

  Last flood scan length is 1, maximum is 1

  Last flood scan time is 4 msec, maximum is 4 msec

  Neighbor Count is 1, Adjacent neighbor count is 1

  Adjacent with neighbor 2.2.2.2

  Suppress hello for 0 neighbor(s)

  Loopback0 is up, line protocol is up

  Internet Address 1.1.1.1/24, Area 0

  Process ID 10, Router ID 1.1.1.1, Network Type LOOPBACK, Cost: 1

  Loopback interface is treated as a stub Host

  在这里我们看到环回口的网络网络类型是Loopback,这是一种特殊的网络类型,只针对环回口存在。我们到R2上看看路由表:

  R2#show 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

  1.0.0.0/32 is subnetted, 1 subnets

  O 1.1.1.1 [110/65] via 192.168.1.1, 00:12:34, Serial1/0

  2.0.0.0/24 is subnetted, 1 subnets

  C 2.2.2.0 is directly connected, Loopback0

  C 192.168.1.0/24 is directly connected, Serial1/0

  C 192.168.2.0/24 is directly connected, Serial1/1

  O 192.168.3.0/24 [110/65] via 192.168.1.1, 00:12:34, Serial1/0

  [110/65] via 192.168.2.3, 00:12:34, Serial1/1

  R2的路由表显示来自环回口的路由,掩码为/32,既我们所说的“主机路由”。在实际应用中,环回口以32位的居多,用作ospf的管理接口。但是如果你想让环回口模拟一个网段,我们可以通过以下配置来消除。

  R1(config)#int loopback 0

  R1(config-if)#ip ospf network point-to-point

  环回口只能配置成point-to-point这种类型,不可以配置成其它的类型。

  回到R2查看路由表:

  R2#show 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

  O 1.1.1.0 [110/65] via 192.168.1.1, 00:00:24, Serial1/0

  2.0.0.0/24 is subnetted, 1 subnets

  C 2.2.2.0 is directly connected, Loopback0

  C 192.168.1.0/24 is directly connected, Serial1/0

  C 192.168.2.0/24 is directly connected, Serial1/1

  O 192.168.3.0/24 [110/65] via 192.168.1.1, 00:00:24, Serial1/0

  [110/65] via 192.168.2.3, 00:00:24, Serial1/1

  我们看到主机路由没有了,取而代之的是一个/24的网段。

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