OSPF综合实验大全.doc

OSPF综合实验大全

OSPF实验1：基本的OSPF配置
实验级别：Assistant
实验拓扑：

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
R1config-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       22.2.0 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。
本文出自 “盖如鹤的步徒” 博客，请务必保留此出处

OSPF实验2：DR/BDR的选取
实验级别：Professional

情况一：

   我们都知道OSPF选取DR的过程是首先比较优先级，在优先级相同的情况下选择RID较高的为DR，但是我多次实验后发现在很多时候DR并非RID最高的路由器，这是什么原因呢？
    在翻阅了卷一有关OSPF DR选取的介绍时，发现了这么一句话：“在一个多址网络上，最先初始化启动的两台具有DR选取资格的路由器将成为DR和BDR路由器。”这是我总结了非最高RID而成为DR的实验，发现这些路由器都是我在进行OSPF配置的时候首先启动ospf的路由器，那会不会是因为这些路由器首先启动了OSPF，然后把自己设置为DR导致其他路由器启动OSPF后就不再进行DR的选取了呢？于是我做了下面的这个实验。

    实验的topo很简单，我就不画了，就是两台路由器通过fa0/0口相连接。
R1:
conf t
ho R1
int lo0
ip add 1.1.1.1 255.255.255.0
int fa0/0
ip add 172.1.1.1 255.255.255.0
no sh
router ospf 10
net 172.1.1.1 0.0.0.0 a 0
R2:
conf t
ho R2
int lo0
ip add 2.2.2.2 255.255.255.0
int fa0/0
ip add 172.1.1.2 255.255.255.0
no sh
R1启动ospf进程后，我们在R2上暂时先不开启ospf，在R1上发现了以下信息：

R1#sho ip ospf int
FastEthernet0/0 is up, line protocol is up 
  Internet Address 172.1.1.1/24, 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 172.1.1.1
  No backup designated router on this network
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    oob-resync timeout 40
    Hello due in 00:00:01
  Index 1/1, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 0, maximum is 0
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 0, Adjacent neighbor count is 0 
  Suppress hello for 0 neighbor(s)

    我们看到R1已经把自己设定为DR了，按照OSPF的规则，新加入的路由器即使RID比DR高，也不会替换DR。这就说明了为什么在有些时候DR并非RID最高的路由器。

    当然这个实验也顺便验证了ospf中DR选取结束后，除非DR路由器出现故障，否则就是有更高优先级或者RID的路由器进入OSPF进程，也是无法改变DR的。既DR是不可以抢夺的！

情况二（本实验参照了ITAA实验室Netfish的实验）：
    ospf中有一个Wait Timer计时器，在这个计时器所限定的时间内起来的OSPF可以视为同时起机。

  TCP/IP卷1第292页对于这个时间间隔是这样定义的：
    Wait Timer:在开始选举DR和BDR之间，路由器等待邻居路由器的Hello数据包通告DR和BDR的时长。长度就是RouterDeadInterval的时间。

    本实验拓扑与情况一相同，不同的地方在于当我们在R1上启动OSPF后，迅速（一定要迅速，非常迅速！40s之内）在R2上也启动ospf，通过debug信息可以看到以下情况：
R1#debug ip ospf adj
OSPF adjacency events debugging is on
R1#debug ip ospf ev 
OSPF events debugging is on
*Aug 14 00:56:19.047: OSPF: Interface FastEthernet0/0 going Up
*Aug 14 00:56:19.051: OSPF: Send hello to 224.0.0.5 area 0 on FastEthernet0/0 from 172.1.1.1
*Aug 14 00:56:19.551: OSPF: Build router LSA for area 0, router ID 1.1.1.1, seq 0x80000001
*Aug 14 00:56:19.555: OSPF: Rcv hello from 2.2.2.2 area 0 from FastEthernet0/0 172.1.1.2
Aug 14 00:56:19.555: OSPF: End of hello processing
R1(config-router)#
*Aug 14 00:56:29.051: OSPF: Send hello to 224.0.0.5 area 0 on FastEthernet0/0 from 172.1.1.1
*Aug 14 00:56:29.451: OSPF: Rcv hello from 2.2.2.2 area 0 from FastEthernet0/0 172.1.1.2
*Aug 14 00:56:29.455: OSPF: 2 Way Communication to 2.2.2.2 on FastEthernet0/0, state 2WAY
*Aug 14 00:56:29.455: OSPF: End of hello processing
R1(config-router)#
*Aug 14 00:56:39.051: OSPF: Send hello to 224.0.0.5 area 0 on FastEthernet0/0 from 172.1.1.1
*Aug 14 00:56:39.427: OSPF: Rcv hello from 2.2.2.2 area 0 from FastEthernet0/0 172.1.1.2
*Aug 14 00:56:39.427: OSPF: End of hello processing
R1(config-router)#
*Aug 14 00:56:49.051: OSPF: Send hello to 224.0.0.5 area 0 on FastEthernet0/0 from 172.1.1.1
*Aug 14 00:56:49.447: OSPF: Rcv hello from 2.2.2.2 area 0 from FastEthernet0/0 172.1.1.2
*Aug 14 00:56:49.447: OSPF: End of hello processing
R1(config-router)#
*Aug 14 00:56:59.051: OSPF: end of Wait on interface FastEthernet0/0
*Aug 14 00:56:59.051: OSPF: DR/BDR election on FastEthernet0/0 
*Aug 14 00:56:59.051: OSPF: Elect BDR 2.2.2.2
*Aug 14 00:56:59.055: OSPF: Elect DR 2.2.2.2
*Aug 14 00:56:59.055:        DR: 2.2.2.2 (Id)   BDR: 2.2.2.2 (Id)
*Aug 14 00:56:59.055: OSPF: Send DBD to 2.2.2.2 on FastEthernet0/0 seq 0x826 opt 0x52 flag 0x7 len 32
*Aug 14 00:56:59.059: OSPF: Send hello to 224.0.0.5 area 0 on FastEthernet0/0 from 172.1.1.1
*Aug 14 00:56:59.459: OSPF: Rcv hello from 2.2.2.2 area 0 from FastEthernet0/0 172.1.1.2
*Aug 14 00:56:59.463: OSPF: Neighbor change Event on interface FastEthernet0/0
*Aug 14 00:56:59.463: OSPF: DR/BDR election on FastEthernet0/0 
*Aug 14 00:56:59.463: OSPF: Elect BDR 1.1.1.1
*Aug 14 00:56:59.467: OSPF: Elect DR 2.2.2.2
*Aug 14 00:56:59.467: OSPF: Elect BDR 1.1.1.1
*Aug 14 00:56:59.467: OSPF: Elect DR 2.2.2.2
*Aug 14 00:56:59.471:        DR: 2.2.2.2 (Id)   BDR: 1.1.1.1 (Id)

这个时候我们发现两个路由器进行了DR/BDR的选取，并且结论和书上介绍的完全一致。

从Debug信息的时间上来看，从启动OSPF进程到开始选举DR和DBR的时间间隔是40秒，在这个时间段内，无论R1还是R2并没有选举DR和DBR。

在RFC2328中对这个时间间隔的定义如下：
Wait Timer
        A single shot timer that causes the interface to exit the
        Waiting state, and as a consequence select a Designated Router
        on the network.  The length of the timer is RouterDeadInterval
        seconds.

因为在广播链路中的RouterDeadInterval是40秒，所以我们看到的这个时间间隔为40秒。

结论：
      并不是先启动OSPF进程的路由器就是DR，而是有一个时间间隔让路由器来等待其他路由器，在这个时间间隔内，路由器相互监听Hello包中的DR和DBR字段中的信息，并且服从优先级原则，可以这样认为——选举是公平的。

实际情况：
     在实际的网络中，即使是40秒内同时起进程的情况也少见；实际情况下是率先启用ospf进程的路由器就很有可能成为DR，第二个启动的就很有可能成为BDR，考虑到路由器故障或者重启等情况，实际的运行效果是：“活”得最久的路由器成为DR（比多长时间不重起） .

OSPF实验3：OSPF over NBMA下的五种网络类型
实验等级：Professional

实验拓扑：

实验基本配置：
1.       首先将R1配置成为帧中继交换机：
frame-relay switching
!
interface Serial1/0
 no ip address
 encapsulation frame-relay
 clock rate 64000
 frame-relay lmi-type ansi
 frame-relay intf-type dce
 frame-relay route 101 interface Serial1/1 102
!
interface Serial1/1
 no ip address
 encapsulation frame-relay
 clock rate 64000
 frame-relay lmi-type ansi
 frame-relay intf-type dce
     frame-relay route 102 interface Serial1/0 101
2.       R2和R3的基本配置：

R2：
interface Loopback0
 ip address 2.2.2.2 255.255.255.0
!        
interface Serial1/0
 ip address 12.1.1.2 255.255.255.0
 encapsulation frame-relay
 serial restart-delay 0
 frame-relay map ip 12.1.1.3 101 broadcast
 no frame-relay inverse-arp
!
router ospf 10
 router-id 2.2.2.2
 log-adjacency-changes
 network 2.2.2.0 0.0.0.255 area 0
 network 12.1.1.0 0.0.0.255 area 0

R3：
interface Loopback0
 ip address 3.3.3.3 255.255.255.0
!
interface Serial1/1
 ip address 12.1.1.3 255.255.255.0
 encapsulation frame-relay
 serial restart-delay 0
 frame-relay map ip 12.1.1.2 102 broadcast
 no frame-relay inverse-arp
!
router ospf 10
 router-id 3.3.3.3
 log-adjacency-changes
 network 3.3.3.0 0.0.0.255 area 0
     network 12.1.1.0 0.0.0.255 area 0
Type1----Non_Broadcast（默认）

我们在R2上show ip ospf neighbor，发现没有邻居。说明在这种情况下邻居需要手动配置！配置如下：
R2：
  R2(config)#router ospf 10
R2(config-router)#neighbor 12.1.1.3
R3：
R3(config)#router ospf 10
R3(config-router)#neighbor 12.1.1.2
此时在R2上查看邻居：
R2#sho ip ospf nei

Neighbor ID     Pri   State           Dead Time   Address         Interface
3.3.3.3           1   FULL/DR         00:01:46    12.1.1.3        Serial1/0
发现邻居已经形成并且有DR与BDR的选举！
在R2上查看接口
R2#show ip ospf interface
Serial1/0 is up, line protocol is up
  Internet Address 12.1.1.2/24, Area 0
  Process ID 10, Router ID 2.2.2.2, Network Type NON_BROADCAST, Cost: 64
  Transmit Delay is 1 sec, State BDR, Priority 1
  Designated Router (ID) 3.3.3.3, Interface address 12.1.1.3
  Backup Designated router (ID) 2.2.2.2, Interface address 12.1.1.2
  Flush timer for old DR LSA due in 00:01:40
  Timer intervals configured, Hello 30, Dead 120, Wait 120, Retransmit 5
在这种网络类型中，hello的间隔是30s。
打开debug信息，我们可以看到在这种网络类型中，OSPF的数据包是单播传送的。
R2#
*Aug 14 14:52:52.819: OSPF: Send hello to 12.1.1.3 area 0 on Serial1/0 from 12.1.1.2
R2#
*Aug 14 14:52:57.087: OSPF: Rcv hello from 3.3.3.3 area 0 from Serial1/0 12.1.1.3
*Aug 14 14:52:57.091: OSPF: End of hello processing
Type2---- Broadcast
首先去掉刚才手动配置的邻居关系：
R2(config)#router ospf 10
R2(config-router)#no neighbor 12.1.1.3 
R3(config)#router ospf 10
R3(config-router)#no neighbor 12.1.1.2
将R2和R3接口的网络类型改成broadcast
R2(config-router)#int s1/0
R2(config-if)#ip ospf network broadcast
R3(config-router)#int s1/1
R3(config-if)#ip ospf network broadcast
一会我们就看到了如下信息
R3#
*Aug 14 14:59:52.823: %OSPF-5-ADJCHG: Process 10, Nbr 2.2.2.2 on Serial1/1 from LOADING to FULL, Loading Done
这说明了在这种网络类型下是不需要手动配置邻居关系的！
R2#show ip ospf nei

Neighbor ID     Pri   State           Dead Time   Address         Interface
3.3.3.3           1   FULL/DR         00:00:39    12.1.1.3        Serial1/0
有DR与BDR的选举。
R2#sho ip ospf int
Serial1/0 is up, line protocol is up
  Internet Address 12.1.1.2/24, Area 0
  Process ID 10, Router ID 2.2.2.2, Network Type BROADCAST, Cost: 64
  Transmit Delay is 1 sec, State BDR, Priority 1
  Designated Router (ID) 3.3.3.3, Interface address 12.1.1.3
  Backup Designated router (ID) 2.2.2.2, Interface address 12.1.1.2
  Timer intervals configured, Hello 10, Dead 40