1.静态路由的工作原理及应用场景

2.默认路由的应用场景及配置方法

3.静态浮动路由的应用场景及配置方法

实验拓扑图

正常情况下c1和c2通过交换机直连就可以通，但是c1和c2和c3都通信不了，因为

它们不在一个网段。需要在R1上面设置两个口f0/0和f0/1 ip ,即c1 c2 和c3的网关，这样c1才能Ping通c3.数据包c1->sw1-》f0/0 查看R1路由表（给R1路由器配置ip地址记得加ip add ,配置完ip 记得no shut启动，路由器互相ping端口的时候记得前面加do  ping,R2(config-if)#do ping 192.168.2.1）

配置好后查看R1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 not set

C    192.168.1.0/24 is directly connected, FastEthernet0/0

C    192.168.2.0/24 is directly connected, FastEthernet0/1

实验拓扑2

c1 ping 192.168.2.2不通行走路线

c1 pingR2f0/0 c1会先到R1，R1会查看路由表，有到192.168.2.2的网段

查看R2是否收到pc1发过来的数据命令

R2#debug ip icmp

ICMP packet debugging is on

R2#

*Mar  1 00:39:22.971: ICMP: echo reply sent, src 192.168.2.2, dst 192.168.1.20

R2#show ip route发现左侧和右侧f0/0和f0/1怎么走，但是没有到达192.168.1.1段怎么走，它会将c1发过来的数据包丢弃

C    192.168.2.0/24 is directly connected, FastEthernet0/0

C    192.168.3.0/24 is directly connected, FastEthernet0/1

解决c1 ping 192.168.2.2通行语法：在R2上加入静态路由命令

R2(config)#ip route  192.168.1.0 255.255.255.0 192.168.2.1

R2(config)#ip route 目标ip 目标掩码  中转IP

同理，c1 ping 192.168.3.1不通，需要在R1上加入静态路由

R1(config)#ip route 192.168.3.0 255.255.255.0 192.168.2.2

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

C    192.168.1.0/24 is directly connected, FastEthernet0/0

C    192.168.2.0/24 is directly connected, FastEthernet0/1

S    192.168.3.0/24 [1/0] via 192.168.2.2（s静态）

此时c1 ping 192.168.3.0 ping通

现实中R1不可能会添加很多静态路由告诉路由器如何走通，此时需要用到默认路由

R3(config)#ip route 0.0.0.0 （任意网段）0.0.0.0（任意掩码） 192.168.3.1（R3上添加默认路由，不管到达哪个路由，都通过192.168.3.1行走）R1，R3可以用到默认路由，R2多个出口的路由器，不能用到默认路由，只能用到静态路由.

R3#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 192.168.3.1 to network 0.0.0.0

C    192.168.3.0/24 is directly connected, FastEthernet0/0

S*  0.0.0.0/0 [1/0] via 192.168.3.1（s*表示默认路由）

R1#write保存R1配置文件

浮动路由拓扑图1

1.R1->R2 或者2.R1->R3->R2 默认走1，如果R1->R2线路出故障，走2