学习日记（路由与交换技术）——浮动静态路由和缺省路由

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一、浮动静态路由

浮动静态路由的作用是实现备份路由

1、原理：如果链路发生故障，浮动静态路由即为主要静态或动态路由提供备份路径的静态路由。浮动静态路由仅在主路由不可用时使用。为了完成此操作，浮动静态路由配置了比主路由更高的管理距离

2、操作：浮动静态路由可配置为通过控制管理距离值来备份主链路。通过配置浮动静态路由做到路由备份，实现在网络中路由的有备无患。

3、简单的例子

拓扑结构：

主机的IP地址：

PC1

PC2

路由器的配置

Router 1:

Router>en

Router#conf t

Enter configuration commands, one per line. End with CNTL/Z.

R2(config)#host

R2(config)#hostname R1

R1(config)#int g 0/0

R1(config-if)#ip add

R1(config-if)#ip address 192.168.1.254 255.255.255.0（接口0/0 的IP地址）

R1(config-if)#no shu

R1(config-if)#no shutdown

R1(config-if)#

%LINK-5-CHANGED: Interface GigabitEthernet0/0, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/0, changed state to up

R1(config-if)#e

R1(config-if)#exit

R1(config)#int g 0/1

R1(config-if)#ip address 192.168.12.1 255.255.255.0（接口0/1 的IP地址）

R1(config-if)#no shutdown

R1(config-if)#

%LINK-5-CHANGED: Interface GigabitEthernet0/1, changed state to up

R1(config-if)#e

R1(config)#int g 0/2

R1(config-if)#ip address 192.168.21.1 255.255.255.0（接口0/2 的IP地址）

R1(config-if)#no shutdown

R1(config-if)#

%LINK-5-CHANGED: Interface GigabitEthernet0/2, changed state to up

R1(config-if)#e

R1(config)#

R1(config)#ip route 192.168.2.0 255.255.255.0 192.168.12.2（配置静态路由）

R1(config)#ip route 192.168.2.0 255.255.255.0 192.168.21.2 10(10代表的是开销，只要比1大就好)（这一条就是备份的，也是浮动静态路由）

R1(config)#do show ip route（查看路由表信息）

Codes: L - local, 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, E - EGP

i - IS-IS, 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

192.168.1.0/24 is variably subnetted, 2 subnets, 2 masks

C 192.168.1.0/24 is directly connected, GigabitEthernet0/0

L 192.168.1.254/32 is directly connected, GigabitEthernet0/0

S 192.168.2.0/24 [1/0] via 192.168.12.2（[1/0] 1代表的是管理距离（管理距离越小，优先级越高）0代表的是开销）

192.168.12.0/24 is variably subnetted, 2 subnets, 2 masks

C 192.168.12.0/24 is directly connected, GigabitEthernet0/1

L 192.168.12.1/32 is directly connected, GigabitEthernet0/1

192.168.21.0/24 is variably subnetted, 2 subnets, 2 masks

C 192.168.21.0/24 is directly connected, GigabitEthernet0/2

L 192.168.21.1/32 is directly connected, GigabitEthernet0/2

R1(config)#

路由器2的配置跟1差不多相同

Router 2 :

R2(config-if)#e

R2(config-if)#exit

R2(config)#int g 0/1

R2(config-if)#ip address 192.168.12.2 255.255.255.0

R2(config-if)#no shutdown

R2(config-if)#

%LINK-5-CHANGED: Interface GigabitEthernet0/1, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/1, changed state to up

R2(config-if)#e

R2(config)#int g 0/2

R2(config-if)#ip address 192.168.21.2 255.255.255.0

R2(config-if)#no shutdown

R2(config-if)#

%LINK-5-CHANGED: Interface GigabitEthernet0/2, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, changed state to up

R2(config-if)#e

R2(config)#ip route 192.168.1.0 255.255.255.0 192.168.12.1

R2(config)#ip route 192.168.1.0 255.255.255.0 192.168.21.1 10

R2#show ip route （特权模式下不用加 do）

Codes: L - local, 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, E - EGP

i - IS-IS, 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

S 192.168.1.0/24 [1/0] via 192.168.12.1

192.168.2.0/24 is variably subnetted, 2 subnets, 2 masks

C 192.168.2.0/24 is directly connected, GigabitEthernet0/0

L 192.168.2.254/32 is directly connected, GigabitEthernet0/0

192.168.12.0/24 is variably subnetted, 2 subnets, 2 masks

C 192.168.12.0/24 is directly connected, GigabitEthernet0/1

L 192.168.12.2/32 is directly connected, GigabitEthernet0/1

192.168.21.0/24 is variably subnetted, 2 subnets, 2 masks

C 192.168.21.0/24 is directly connected, GigabitEthernet0/2

L 192.168.21.2/32 is directly connected, GigabitEthernet0/2

结果验证

PC1 ping PC2

二、缺省路由

什么时候用到缺省路由呢？

答：当数据无论想去那个网络，都得通过那个路由器，这时候就可以把路由器设置成缺省（默认）路由。

例子：

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