OSPF实验:基本的OSPF配置思科认证

文章作者 100test 发表时间 2009:06:15 07:19:22
来源 100Test.Com百考试题网


  实验级别:Assistant
  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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