实验目的：

1、掌握静态浮动路由的基本配置。

2、理解静态浮动路由的主备切换。

实验拓扑：

实验步骤：

1、依据图中拓扑配置各设备的IP地址，并保证直连连通性;

在R1上做如下配置：

R1(config)#int f0/0

R1(config-if)#no shutdown

R1(config-if)#ip address 12.1.1.1 255.255.255.0

R1(config-if)#exit

R1(config)#int f1/0

R1(config-if)#no shutdown

R1(config-if)#ip address 13.1.1.1 255.255.255.0

R1(config-if)#exit

R1(config)#int loopback 1

R1(config-if)#ip address 1.1.1.1 255.255.255.255

R1(config-if)#exit

在R2上做如下配置：

R2(config)#int f0/0

R2(config-if)#no shutdown

R2(config-if)#ip address 12.1.1.2 255.255.255.0

R2(config-if)#exit

R2(config-if)#exit

R2(config)#int loopback 1

R2(config-if)#ip address 8.8.8.8 255.255.255.255

R2(config-if)#exit

在R3上做如下配置

R3(config)#int f0/0

R3(config-if)#no shutdown

R3(config-if)#ip address 13.1.1.3 255.255.255.0

R3(config-if)#exit

R3(config)#int loopback 1

R3(config-if)#ip address 8.8.8.8 255.255.255.255

R3(config-if)#exit

在其中一台路由器上进行连通性测试：

R1#ping 12.1.1.2


Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 12.1.1.2, timeout is 2 seconds:

.!!!!

Success rate is 80 percent (4/5), round-trip min/avg/max = 20/34/48 ms

R1#ping 13.1.1.3


Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 13.1.1.3, timeout is 2 seconds:

.!!!!

Success rate is 80 percent (4/5), round-trip min/avg/max = 16/31/48 ms

此时说明直连连接没有问题。

2.在R1上部署浮动静态路由，如下：

R1(config)#ip route 0.0.0.0 0.0.0.0 12.1.1.2

R1(config)#ip route 0.0.0.0 0.0.0.0 13.1.1.3 100 

查看R1的路由表：

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 12.1.1.2 to network 0.0.0.0


     1.0.0.0/32 is subnetted, 1 subnets

C       1.1.1.1 is directly connected, Loopback1

     12.0.0.0/24 is subnetted, 1 subnets

C       12.1.1.0 is directly connected, FastEthernet0/0

     13.0.0.0/24 is subnetted, 1 subnets

C       13.1.1.0 is directly connected, FastEthernet1/0

S*   0.0.0.0/0 [1/0] via 12.1.1.2

由于管理距离的原因，备用路由被“隐藏”起来，只有最优的路由被放置进路由表。

3.此时进行浮动路由测试，如下：

在R2和R3上开启ICMP实时调试：

R2#debug ip icmp

ICMP packet debugging is on

R3#debug ip icmp

ICMP packet debugging is on

此时在R1上ping 互联网地址，如下：

R1#ping 8.8.8.8


Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 8.8.8.8, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 28/36/48 ms

再到R2上查看：

R2#debug ip icmp

ICMP packet debugging is on

R2#

*Mar  1 11:42:30.189: ICMP: echo reply sent, src 8.8.8.8, dst 12.1.1.1

*Mar  1 11:42:30.237: ICMP: echo reply sent, src 8.8.8.8, dst 12.1.1.1

*Mar  1 11:42:30.269: ICMP: echo reply sent, src 8.8.8.8, dst 12.1.1.1

*Mar  1 11:42:30.317: ICMP: echo reply sent, src 8.8.8.8, dst 12.1.1.1

*Mar  1 11:42:30.345: ICMP: echo reply sent, src 8.8.8.8, dst 12.1.1.1

可以看到，R2进行ICMP回应，说明正常情况下通往互联网的数据包往主链路走。此时关闭R1的主链路，模拟主链路出现故障，并查看路由表：

R1(config)#int f0/0

R1(config-if)#shutdown

R1(config-if)#end

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 13.1.1.3 to network 0.0.0.0


     1.0.0.0/32 is subnetted, 1 subnets

C       1.1.1.1 is directly connected, Loopback1

     13.0.0.0/24 is subnetted, 1 subnets

C       13.1.1.0 is directly connected, FastEthernet1/0

S*   0.0.0.0/0 [100/0] via 13.1.1.3

此时主链路路由消失，备用路由“浮出”路由表，再次在R1上Ping互联网地址，如下：

R1#ping 8.8.8.8


Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 8.8.8.8, timeout is 2 seconds:

.!!!!


Success rate is 80 percent (4/5), round-trip min/avg/max = 24/30/32 ms

切换到R3上：

R3#

*Mar  1 07:58:25.386: ICMP: echo reply sent, src 8.8.8.8, dst 13.1.1.1

*Mar  1 07:58:25.426: ICMP: echo reply sent, src 8.8.8.8, dst 13.1.1.1

*Mar  1 07:58:25.458: ICMP: echo reply sent, src 8.8.8.8, dst 13.1.1.1

*Mar  1 07:58:25.490: ICMP: echo reply sent, src 8.8.8.8, dst 13.1.1.1