思科OSPF实验1：基本的OSPF配置

OSPF实验1：基本的OSPF配置

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

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, Loopback0C

192.168.1.0/24 is directly connected, Serial1/0C

192.168.2.0/24 is directly connected, Serial1/1O

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。