第 4 章 RIP

动态路由协议包括距离向量路由协议和链路状态路由协议。RIP(Routing Information

Protocols,路由信息协议)是使用最广泛的距离向量路由协议。RIP 是为小型网络环境设

计的,因为这类协议的路由学习及路由更新将产生较大的流量,占用过多的带宽。

4.1 RIP 概述

RIP 是由 Xerox 在 70 年×××发的,最初定义在 RFC1058 中。RIP 用两种数据包传输更新:

更新和请求,每个有 RIP 功能的路由器默认情况下每隔 30 秒利用 UDP 520 端口向与它直连

的网络邻居广播(RIP v1)或组播(RIP v2)路由更新。因此路由器不知道网络的全局情况,

如果路由更新在网络上传播慢,将会导致网络收敛较慢,造成路由环路。为了避免路由环路,

RIP 采用水平分割、毒性逆转、定义最大跳数、闪式更新、抑制计时 5 个机制来避免路由环

路。

RIP 协议分为版本 1 和版本 2。不论是版本 1 或版本 2,都具备下面的特征:

1. 是距离向量路由协议;

2. 使用跳数(Hop Count)作为度量值;

3.默认路由更新周期为 30 秒;

4. 管理距离(AD)为 120;

5. 支持触发更新;

6. 最大跳数为 15 跳;

7. 支持等价路径,默认 4 条,最大 6 条;

8. 使用 UDP520 端口进行路由更新。

而 RIPv1 和 RIPv2 的区别如表 4-1。

表 4-1 RIPv1 和 RIPv2 的区别

RIPv1  RIPv2

表 4-1 RIPv1 和 RIPv2 的区别

RIPv1  RIPv2

在路由更新的过程中不携带子网信息  在路由更新的过程中携带子网信息

不提供认证  提供明文和 MD5 认证

不支持 VLSM 和 CIDR  支持 VLSM 和 CIDR

采用广播更新  采用组播(224.0.0.9)更新

有类别(Classful)路由协议  无类别(Classless)路由协议

4.2 RIPv1

4.2.1 实验 1:RIPv1 基本配置

1.实验目的

通过本实验可以掌握:

(1)在路由器上启动 RIPv1 路由进程

(2)启用参与路由协议的接口,并且通告网络

(3)理解路由表的含义

(4)查看和调试 RIPv1 路由协议相关信息

2.拓扑结构

实验拓扑如图 4-1 所示。

图 4-1 RIPv1 的基本配置

3.实验步骤

(1)步骤 1:配置路由器 R1

R1(config)# router rip //启动 RIP 进程

R1(config-router)# version 1 //配置 RIP 版本 1

R1(config-router)# network 1.0.0.0 //通告网络

R1(config-router)# network 192.168.12.0

(2)步骤 2:配置路由器 R2

R2(config)# router rip

R2(config-router)# version 1

R2(config-router)# network 192.168.12.0

R2(config-router)# network 192.168.23.0

(3)步骤 3:配置路由器 R3

R3(config)# router rip

R3(config-router)# version 1

R3(config-router)# network 192.168.23.0

R3(config-router)# network 192.168.34.0

(4)步骤 4:配置路由器 R4

R4(config)# router rip

R4(config-router)# version 1

R4(config-router)# network 192.168.34.0

R4(config-router)# network 4.0.0.0

4.实验调试

(1)  show ip route

该命令用来查看路由表。

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 192.168.12.0/24 is directly connected, Serial0/0/0

1.0.0.0/24 is subnetted, 1 subnets

C 1.1.1.0 is directly connected, Loopback0

R 4.0.0.0/8 [120/3] via 192.168.12.2, 00:00:03, Serial0/0/0

R 192.168.23.0/24 [120/1] via 192.168.12.2, 00:00:03, Serial0/0/0

R 192.168.34.0/24 [120/2] via 192.168.12.2, 00:00:03, Serial0/0/0

R 4.0.0.0/8 [120/3] via 192.168.12.2, 00:00:03, Serial0/0/0

R 192.168.23.0/24 [120/1] via 192.168.12.2, 00:00:03, Serial0/0/0

R 192.168.34.0/24 [120/2] via 192.168.12.2, 00:00:03, Serial0/0/0

以上输出表明路由器 R1 学到了 3 条 RIP 路由,其中路由条目“R 4.0.0.0/8 [120/3]

via 192.168.12.2, 00:00:03, Serial0/0/0

R 4.0.0.0/8 [120/3]

via 192.168.12.2, 00:00:03, Serial0/0/0”的含义如下:

① R:路由条目是通过 RIP 路由协议学习来的;

② 4.0.0.0/8 :目的网络;

③ 120:RIP 路由协议的默认管理距离;

④ 3: 度量值,从路由器 R1 到达网络 4.0.0.0/8 的度量值为 3 跳;

⑤ 192.168.12.2:下一跳地址;

⑥ 00:00:03:距离下一次更新还有 27(30-3)秒;

⑦ Serial0/0/0:接收该路由条目的本路由器的接口。

同时通过该路由条目的掩码长度可以看到,RIPv1 确实不传递子网信息。

(2)show ip protocols

该命令查看 IP 路由协议配置和统计信息。

R1# show ip protocols

【注意 】

“//”后的信息表示注释,不是输出内容。

Routing Protocol is "rip"

//路由器上运行的路由协议是 RIP

Outgoing update filter list for all interfaces is not set

//在出方向上没有设置过滤列表

Incoming update filter list for all interfaces is not set

//在入方向上没有设置过滤列表

Sending updates every 30 seconds, next due in 23 seconds

//更新周期是 30 秒,距离下次更新还有 23 秒

【注意 】

为了防止更新同步,RIP 会以 15%的误差发送更新,即实际发送更新的周期的范围是

25.5-30 秒。

Invalid after 180 seconds, hold down 180, flushed after 240

// invalid after:路由条目如果在 180 秒还没有收到更新,则被标记为无效

【技术要点 】

被标记为无效的路由条目类似如下所示:

R 4.0.0.0/8 is possibly down, routing via 192.168.12.2, Serial0/0/0

可以通过很多方式使路由条目进入无效周期,例如在接口上加拒绝接收 UDP520 端口的

ACL,还比如将接口设置为被动接口等。

// hold down:抑制计时器的时间为 180 秒

// flushed after:路由条目如果在 240 秒还没有收到更新,则从路由表中删除此路由条目

【提示 】

可以通过下面的命令来调整以上三个时间参数:

R1(config-router)# timers basic  update invalid holddown flushed

Redistributing: rip

//只运行 RIP协议,没有其它的协议重分布进来

Default version control: send version 1, receive version 1

//默认发送版本 1 的路由更新,接收本版 1 的路由更新

Interface Send Recv Triggered RIP Key-chain

Serial0/0/0 1 1

Loopback0 1 1

//以上三行显示了运行 RIP协议的接口,以及可以接收和发送的 RIP路由更新的版本

Automatic network summarization is in effect

//RIP 路由协议默认开启自动汇总功能

Maximum path: 4

//RIP 路由协议可以支持 4 条等价路径,最大为 6 条

【提示 】

可以通过下面的命令来修改 RIP 路由协议支持等价路径的条数:

R1(config-router)# maximum-paths number-paths

Routing for Networks:

1.0.0.0

192.168.12.0

//以上三行表明 RIP 通告的网络

Routing Information Sources:

Gateway Distance Last Update

192.168.12.2 120 00:00:03

//以上三行表明路由信息源,其中:

// gateway:学习路由信息的路由器的接口地址,也就是下一跳地址

// distance:管理距离

// last update:更新发生在多长时间以前

Distance: (default is 120)

//默认管理距离是 120

(3)debug ip rip

该命令可以查看 RIP 路由协议的动态更新过程。

R1#clear ip route *

R1#debug ip rip

clear ip route *

R1#debug ip rip

Feb 9 12:43:13.311: RIP: sending request on Serial0/0/0 to 255.255.255.255

Feb 9 12:43:13.315: RIP: sending request on Loopback0 to 255.255.255.255

Feb 9 12:43:13.323: RIP:  received v1 update from 192.168.12.2 on  Serial0/0/0

Feb 9 12:43:13.323: 4.0.0.0 in 3 hops

Feb 9 12:43:13.323: 192.168.23.0 in 1 hops

Feb 9 12:43:13.323: 192.168.34.0 in 2 hops

Feb 9 12:43:15.311: RIP:  sending v1 flash update to  255.255.255.255 via  Loopback0 (1.1.1.1)

Feb 9 12:43:15.311: RIP: build flash update entries

Feb 9 12:43:15.311: network 4.0.0.0 metric 4

Feb 9 12:43:15.311: network 192.168.12.0 metric 1

Feb 9 12:43:15.311: network 192.168.23.0 metric 2

Feb 9 12:43:15.311: network 192.168.34.0 metric 3

Feb 9 12:43:15.311: RIP:  sending v1 flash update to  255.255.255.255 via  Serial0/0/0

(192.168.12.1)

Feb 9 12:43:15.311: RIP: build flash update entries

Feb 9 12:43:15.311: network 1.0.0.0 metric 1

通过以上输出,可以看到 RIPv1 采用广播更新(255.255.255.255),分别向 Loopback0

和 s0/0/0 发送路由更新,同时从 s0/0/0 接收三条路由更新,分别是 4.0.0.0,度量值是 3

跳;192.168.34.0, 度量值是 2 跳;192.168.23.0,度量值是 1 跳。

【技术要点】

flash update

flash update(闪式更新)指的是当网络上某个路径的度量值发生变化,路由器立即

发出更新信息,而不管是否到达常规路由信息更新的周期。

4.2.2 实验 2:被动接口与单播更新

1.实验目的

通过本实验可以掌握:

(1)被动接口的含义、配置和应用场合

(2)单播更新的应用场合和配置

2.拓扑结构

实验拓扑如图 4-2 所示。

图 4-2 配置被动接口

由于以太口 g0/0 和 g0/1 连接主机,不需要向这些接口发送路由更新,所以可以考虑将

路由器的该接口设置为被动接口。

3.实验步骤

(1)步骤 1:配置路由器 R1

R1(config)# router rip

R1(config-router)# version 1

R1(config-router)# network 10.0.0.0

R1(config-router)# network 172.16.0.0

R1(config-router)# network 192.168.12.0

R1(config-router)# passive-interface GigabitEthernet0/0

R1(config-router)# passive-interface GigabitEthernet0/1

(2)步骤 2:配置路由器 R2

R2(config)# router rip

R2(config-router)# version 1

R2(config-router)# network 192.168.12.0

R2(config-router)# network 2.0.0.0

4.实验调试

R1# debug ip rip

R1# clear ip route *

Feb 9 13:24:41.275: RIP: sending request on Serial0/0/0 to 255.255.255.255

Feb 9 13:24:41.283: RIP: received v1 update from 192.168.12.2 on Serial0/0/0

Feb 9 13:24:41.283: 2.0.0.0 in 1 hops

Feb 9 13:24:43.275: RIP: sending v1 flash update to 255.255.255.255 via  Serial0/0/0

(192.168.12.1)

Feb 9 13:24:43.275: RIP: build flash update entries

Feb 9 13:24:43.275: network 10.0.0.0 metric 1

Feb 9 13:24:43.275: network 172.16.0.0 metric 1

从以上输出可以看出,路由器 R1 确实不向被动接口 g0/0 和 g0/1 发送路由更新。

【技术要点 】

被动接口只能接收路由更新,不能以广播或组播方式发送更新,但是可以以单播的方式

发送更新,配置单播更新的命令如下:

R1(config-router)# neighbor  A.B.C.D

【实例 】

如图 4-3 所示,路由器 R1 只想把路由更新送到路由器 R3 上,由于 RIPv1 路由协议采用

广播更新,默认情况下,路由更新将发送给以太网上任何一个设备,为了防止这种情况发生,

把路由器 R1 的 g0/0 配置成被动接口,然而路由器 R1 还想把路由更新发送给 R3,这时候必

须采用单播更新,为指定的相邻路由器 R3 发送路由更新。路由器 R1 具体的配置如下:

R1(config)# router rip

R1(config-router)# passive-interface GigabitEthernet0/0

R1(config-router)# neighbor 172.16.1.3

图 4-3 配置单播更新

4.2.3 实验 3:使用子网地址

1.实验目的

通过本实验可以掌握:

(1)RIPv1 使用子网地址的条件

(2)RIPv1 接收子网路由的原则

2.拓扑结构

实验拓扑如图 4-4 所示。

图 4-4 RIPv1 使用子网地址

3.实验步骤

(1)步骤 1:配置路由器 R1

R1(config)# router rip

R1(config-router)# version 1

R1(config-router)# network 172.16.0.0

(2)步骤 2:配置路由器 R2

R2(config)# router rip

R2(config-router)# version 1

R2(config-router)# network 172.16.0.0

4.实验调试

分别查看 R1、R2 的路有表:

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

172.16.0.0/24 is subnetted, 3 subnets

C 172.16.1.0 is directly connected, Loopback0

C 172.16.2.0 is directly connected, Serial0/0/0

R 172.16.3.0 [120/1] via 172.16.2.2, 00:00:03, Serial0/0/0

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

172.16.0.0/24 is subnetted, 3 subnets

R 172.16.1.0 [120/1] via 172.16.2.1, 00:00:21, Serial0/0/0

C 172.16.2.0 is directly connected, Serial0/0/0

C 172.16.3.0 is directly connected, Loopback0

从路由器 R1 和 R2 的路由表输出可以看出,它们互相学习到了 24 位的路由条目,从而

可以说明,某些情况下 RIPv1 更新确实可以携带子网信息。

【技术要点 】

RIPv1 路由更新可以携带子网信息必须同时满足两个条件:

(1)整个网络所有地址在同一个主类网络;

(2)子网掩码长度必须相同。

【思考 】

假如在图 4-4 中,路由器 R2 的 s0/0/0 接口的 IP 地址的掩码长度为 25 位,那么,R2

的路由表是怎样的呢?结果如下:

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

172.16.0.0/ 16 is variably subnetted,  3 subnets, 2 masks

R 172.16.1.0/25 [120/1] via 172.16.2.1, 00:00:17, Serial0/0/0

C 172.16.2.0/25 is directly connected, Serial0/0/0

C 172.16.3.0/24 is directly connected, Loopback0

由此得出 RIP v1 接收子网路由的原则:如果路由器收到的是子网路由条目,那么就以接

收该路由条目的接口的掩码长度作为该子网路由条目的掩码长度。

4.3 RIPv2

4.3.1 实验 4:RIPv2 基本配置

1.实验目的

通过本实验可以掌握:

(1)在路由器上启动 RIPv2 路由进程

(2)启用参与路由协议的接口,并且通告网络

(3)auto-summary 的开启和关闭

(4)查看和调试 RIPv2 路由协议相关信息

2.拓扑结构

实验拓扑如图 4-1 所示。

3.实验步骤

(1)步骤 1:配置路由器 R1

R1(config)# router rip

R1(config-router)# version 2

R1(config-router)# no auto-summary

R1(config-router)# network 1.0.0.0

R1(config-router)# network 192.168.12.0

(2)步骤 2:配置路由器 R2

R2(config)# router rip

R2(config-router)# version 2

R2(config-router)# no auto-summary

R2(config-router)# network 192.168.12.0

R2(config-router)# network 192.168.23.0

(3)步骤 3:配置路由器 R3

R3(config)# router rip

R3(config-router)# version 2

R3(config-router)# no auto-summary

R3(config-router)# network 192.168.23.0

R3(config-router)# network 192.168.34.0

(4)步骤 4:配置路由器 R4

R4(config)# router rip

R4(config-router)# version 2

R4(config-router)# no auto-summary

R4(config-router)# network 192.168.34.0

R4(config-router)# network 4.0.0.0

4.实验调试

(1)  show ip route

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 192.168.12.0/24 is directly connected, Serial0/0/0

1.0.0.0/24 is subnetted, 1 subnets

C 1.1.1.0 is directly connected, Loopback0

4.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

R 4.4.4.0/24 [120/3] via 192.168.12.2, 00:00:22, Serial0/0/0

R 192.168.23.0/24 [120/1] via 192.168.12.2, 00:00:22, Serial0/0/0

R 192.168.34.0/24 [120/2] via 192.168.12.2, 00:00:22, Serial0/0/0

从上面输出的路由条目“ 4.4.4.0/24”,可以看到 RIPv2 路由更新是携带子网信息的。

(2)show ip protocols

R1#show ip protocols

Routing Protocol is "rip"

Outgoing update filter list for all interfaces is not set

Incoming update filter list for all interfaces is not set

Sending updates every 30 seconds, next due in 19 seconds

Invalid after 180 seconds, hold down 180, flushed after 240

Redistributing: rip

Default version control: send version 2, receive version 2

Interface Send Recv Triggered RIP Key-chain

Serial0/0/0 2 2

Loopback0 2 2

// RIPv2 默认情况下只接收和发送版本 2 的路由更新

【提示 】

可以通过命令“ ip rip send version”和“ ip rip receive version”来控制在路由

器接口上接收和发送的版本,例如在 s0/0/0 接口上接收版本 1 和 2 的路由更新,但是只发

送版本 2 的路由更新,配置如下:

R1(config-if)# ip rip send version 2

R1(config-if)# ip rip receive version 1 2

【注意 】

接口特性是优于进程特性的,对于本实验,虽然在 RIP 进程中配置了“ version 2” ,

但是如果在接口上配置了“ ip rip receive version 1 2” ,则该接口可以接收版本 1 和

2 的路由更新。

Automatic network summarization is not in effect

Maximum path: 4

Routing for Networks:

1.0.0.0

192.168.12.0

Routing Information Sources:

Gateway Distance Last Update

192.168.12.2 120 00:00:26

Distance: (default is 120)

4.3.2 实验 5:RIPv2 手工汇总

1.实验目的

通过本实验可以掌握:

(1)RIPv2 路由的手工汇总

(2)RIPv2 不支持 CIDR 汇总

(3)RIPv2 可以传递 CIDR 汇总

2.拓扑结构

实验拓扑如图 4-5 所示。

图 4-5 RIPv2 路由手工汇总

3.实验步骤

路由器 R1、R2 和 R3 的配置和 4 4.3.1 实验 4 相同,R4 的配置如下:

R4(config)# router rip

R4(config-router)# version 2

R4(config-router)# no auto-summary

R4(config-router)# network 192.168.34.0

R4(config-router)# network 4.0.0.0

R4(config)# interface s0/0/0

R4(config-if)# ip summary-address rip 4.4.0.0 255.255.252.0//RIP 手工路由汇总

4.实验调试

(1)在没有执行汇总之前路由器 R1 的路由表如下:

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 192.168.12.0/24 is directly connected, Serial0/0/0

1.0.0.0/24 is subnetted, 1 subnets

C 1.1.1.0 is directly connected, Loopback0

4.0.0.0/24 is subnetted, 4 subnets

R 4.4.0.0 [120/3] via 192.168.12.2, 00:00:21, Serial0/0/0

R 4.4.1.0 [120/3] via 192.168.12.2, 00:00:21, Serial0/0/0

R 4.4.2.0 [120/3] via 192.168.12.2, 00:00:12, Serial0/0/0

R 4.4.3.0 [120/3] via 192.168.12.2, 00:00:05, Serial0/0/0

R 4.4.0.0 [120/3] via 192.168.12.2, 00:00:21, Serial0/0/0

R 4.4.1.0 [120/3] via 192.168.12.2, 00:00:21, Serial0/0/0

R 4.4.2.0 [120/3] via 192.168.12.2, 00:00:12, Serial0/0/0

R 4.4.3.0 [120/3] via 192.168.12.2, 00:00:05, Serial0/0/0

R 192.168.23.0/24 [120/1] via 192.168.12.2, 00:00:21, Serial0/0/0

R 192.168.34.0/24 [120/2] via 192.168.12.2, 00:00:22, Serial0/0/0

从上面的输出看到路由器 R1 的路由表中有 R4 的 4 条环回接口的明细路由。

(2)在执行汇总以后路由器 R1 的路由表如下:

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 192.168.12.0/24 is directly connected, Serial0/0/0

1.0.0.0/24 is subnetted, 1 subnets

C 1.1.1.0 is directly connected, Loopback0

4.0.0.0/22 is subnetted, 1 subnets

R 4.4.0.0 [120/3] via 192.168.12.2, 00:00:21, Serial0/0/0

R 192.168.23.0/24 [120/1] via 192.168.12.2, 00:00:21, Serial0/0/0

R 192.168.34.0/24 [120/2] via 192.168.12.2, 00:00:22, Serial0/0/0

上面的输出表明在路由器 R1 的路由表中接收到汇总路由,当然 R2,R3 上也能收到汇总

路由。

【思考】

现在将路由器 R4 上四个环回接口 lo0-lo4 的地址分别修改为 192.168.96.4/24,

192.168.97.4/24, 192.168.98.4/24, 192.168.99.4/24,在 s0/0/0 接口下还能够实现路由

汇总吗?R4 上做如下的配置:

R4(config-if)# router rip

R4(config-router)# network 192.168.96.0

R4(config-router)# network 192.168.97.0

R4(config-router)# network 192.168.98.0

R4(config-router)# network 192.168.99.0

R4(config-if)# ip summary-address rip 192.168.96.0 255.255.252.0

路由器会提示如下信息:

“ Summary mask must be greater or equal to major net”

显示的提示信息表明汇总后的掩码长度必须要大于或等于主类网络的掩码程度,因为

“22<24”,所以不能汇总。

所以  RIPv2 不支持 CIDR 汇总,但是可以传递 CIDR 汇总。

解决方案如下:

(1)用静态路由发布被汇总的路由

R4(config)# ip route 192.168.96.0 255.255.252.0 null0

(2)将静态路由重分布到 RIP 网络中

R4(config)# router rip

R4(config-router)# redistribute static //将静态路由重分布到 RIP 路由协议中

R4(config-router)# no network 192.168.96.0

R4(config-router)# no network 192.168.97.0

R4(config-router)# no network 192.168.98.0

R4(config-router)# no network 192.168.99.0

(3)在路由器 R1 上查看路由表

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, 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 192.168.12.0/24 is directly connected, Serial0/0/0

1.0.0.0/24 is subnetted, 1 subnets

C 1.1.1.0 is directly connected, Loopback0

R 192.168.23.0/24 [120/1] via 192.168.12.2, 00:00:18, Serial0/0/0

R 192.168.34.0/24 [120/2] via 192.168.12.2, 00:00:18, Serial0/0/0

R 192.168.96.0/22 [120/3] via 192.168.12.2, 00:00:18, Serial0/0/0

通过输出不难看出 RIPv2 是可以传递 CIDR 汇总信息的。

4.3.3 实验 6:RIPv2 认证和触发更新

1.实验目的

通过本实验可以掌握:

(1)RIPv2 明文认证的配置和匹配原则

(2)RIPv2 MD5 认证的配置和匹配原则

(3)RIPv2 触发更新

2.拓扑结构

实验拓扑如图 4-1 所示。

3.实验步骤

(1)步骤 1:配置路由器 R1

R1(config)# key chain test //配置钥匙链

R1(config-keychain)# key 1 //配置 KEY ID

R1(config-keychain-key)# key-string cisco //配置 KEY ID 的密匙

R1(config)# interface s0/0/0

R1(config-if)# ip rip authentication mode text

//启用认证,认证模式为明文,默认认证模式就是明文,所以也可以不用指定

R1(config-if)# ip rip authentication key-chain test //在接口上调用钥匙链

R1(config-if)# ip rip triggered //在接口上启用触发更新

(2)步骤 2:配置路由器 R2

R2(config)# key chain test

R2(config-keychain)# key 1

R2(config-keychain-key)# key-string cisco

R2(config)# interface s0/0/0

R2(config-if)# ip rip triggered

R2(config-if)# ip rip authentication key-chain test

R2(config-if)# interface s0/0/1

R2(config-if)# ip rip authentication key-chain test

R2(config-if)# ip rip triggered

(3)步骤 3:配置路由器 R3

R3(config)# key chain test

R3(config-keychain)# key 1

R3(config-keychain-key)# key-string cisco

R3(config)# interface s0/0/0

R3(config-if)# ip rip authentication key-chain test

R3(config-if)# ip rip triggered

R3(config-if)# interface s0/0/1

R3(config-if)# ip rip authentication key-chain test

R3(config-if)# ip rip triggered

(4)步骤 4:配置路由器 R4

R4(config)# key chain test

R4(config-keychain)# key 1

R4(config-keychain-key)# key-string cisco

R4(config)# interface s0/0/0

R4(config-if)# ip rip authentication key-chain test

R4(config-if)# ip rip triggered

4.实验调试

(1) show ip protocols

R2# show ip protocols

Routing Protocol is "rip"

Outgoing update filter list for all interfaces is not set

Incoming update filter list for all interfaces is not set

Sending updates every 30 seconds, next due in 4 seconds

Invalid after 180 seconds,  hold down 0, flushed after 240

// 由于触发更新,hold down 计时器自动为 0

Redistributing: rip

Default version control: send version 2, receive version 2

Interface Send Recv Triggered RIP Key-chain

Serial0/0/0 2 2 Yes test

Serial0/0/1 2 2 Yes test

//以上两行表明 s0/0/0 和 s0/0/1 接口启用了认证和触发更新

Automatic network summarization is not in effect

Maximum path: 4

Routing for Networks:

192.168.12.0

192.168.23.0

Routing Information Sources:

Gateway Distance Last Update

192.168.12.1 120 00:26:10

192.168.23.3 120 00:26:01

Distance: (default is 120)

(2) debug ip rip

R2# debug ip rip

RIP protocol debugging is on

R2# clear ip route *

*Feb 11 13:51:31.827: RIP: sending  triggered request on Serial0/0/0 to 224.0.0.9

*Feb 11 13:51:31.831: RIP: sending  triggered request on Serial0/0/1 to 224.0.0.9

*Feb 11 13:51:31.843: RIP: sending triggered request on Serial0/0/0 to 224.0.0.9

*Feb 11 13:51:31.847: RIP: sending triggered request on Serial0/0/1 to 224.0.0.9

*Feb 11 13:51:31.847: RIP: send v2  triggered flush update to 192.168.12.1 on Serial0/0/0 with

no route

*Feb 11 13:51:31.851: RIP: start retransmit timer of 192.168.12.1

*Feb 11 13:51:31.855: RIP: send v2 triggered flush update to 192.168.23.3 on Serial0/0/1 with

no route

*Feb 11 13:51:31.855: RIP: start retransmit timer of 192.168.23.3

*Feb 11 13:51:32.019: RIP: received packet with  text authentication cisco

*Feb 11 13:51:32.019: RIP: received v2 triggered update from 192.168.12.1 on Serial0/0/0

*Feb 11 13:51:32.023: RIP: sending v2 ack to 192.168.12.1 via Serial0/0/0 (192.168.12.2),

flush, seq# 1

*Feb 11 13:51:32.027: 1.1.1.0/24 via 0.0.0.0 in 1 hops

*Feb 11 13:51:32.031: RIP: received packet with text authentication cisco

*Feb 11 13:51:32.035: RIP: received v2 triggered update from 192.168.23.3 on Serial0/0/1

*Feb 11 13:51:32.035: RIP: sending v2  ack to 192.168.23.3 via Serial0/0/1(192.168.23.2),

flush, seq# 2

*Feb 11 13:51:32.039: 192.168.34.0/24 via 0.0.0.0 in 1 hops

*Feb 11 13:51:32.043: 4.4.4.0/24 via 0.0.0.0 in 2 hops

*Feb 11 13:51:32.071: RIP: received packet with text authentication cisco

*Feb 11 13:51:32.071: RIP: received v2 triggered update from 192.168.23.3 on Serial0/0/1

*Feb 11 13:51:32.071: RIP: sending v2 ack to 192.168.23.3 via Serial0/0/1(192.168.23.2),

flush, seq# 3

*Feb 11 13:51:32.075: 192.168.34.0/24 via 0.0.0.0 in 1 hops

*Feb 11 13:51:32.079: 4.4.4.0/24 via 0.0.0.0 in 2 hops

*Feb 11 13:51:32.083: RIP: received packet with text authentication cisco

*Feb 11 13:51:32.083: RIP: received v2 triggered ack from 192.168.23.3 on Serial0/0/1

flush seq# 2

*Feb 11 13:51:32.087: RIP: send v2 triggered update to 192.168.23.3 on Serial0/0/1

*Feb 11 13:51:32.087: RIP: build update entries

*Feb 11 13:51:32.091: route 176: 192.168.12.0/24 metric 1, tag 0

*Feb 11 13:51:32.091: route 181: 1.1.1.0/24 metric 2, tag 0

*Feb 11 13:51:32.095: RIP: Update contains 2 routes, start 176, end 188

*Feb 11 13:51:32.095: RIP: start retransmit timer of 192.168.23.3

*Feb 11 13:51:32.099: RIP: received packet with text authentication cisco

*Feb 11 13:51:32.099: RIP: received v2 triggered update from 192.168.12.1 on Serial0/0/0

*Feb 11 13:51:32.103: RIP: sending v2 ack to 192.168.12.1 via Serial0/0/0 (192.168.12.2),

flush, seq# 2

*Feb 11 13:51:32.107: 1.1.1.0/24 via 0.0.0.0 in 1 hops

*Feb 11 13:51:32.107: RIP: received packet with text authentication cisco

*Feb 11 13:51:32.111: RIP: received v2 triggered ack from 192.168.12.1 on Serial0/0/0

flush seq# 3

*Feb 11 13:51:32.111: RIP: send v2 triggered update to 192.168.12.1 on Serial0/0/0

*Feb 11 13:51:32.115: RIP: build update entries

*Feb 11 13:51:32.115: route 178: 192.168.23.0/24 metric 1, tag 0

*Feb 11 13:51:32.119: route 184: 192.168.34.0/24 metric 2, tag 0

*Feb 11 13:51:32.123: route 187: 4.4.4.0/24 metric 3, tag 0

*Feb 11 13:51:32.123: RIP: Update contains 3 routes, start 178, end 188

*Feb 11 13:51:32.123: RIP: start retransmit timer of 192.168.12.1

*Feb 11 13:51:32.263: RIP: received packet with text authentication cisco

*Feb 11 13:51:32.263: RIP: received v2 triggered ack from 192.168.23.3 on Serial0/0/1

seq# 3

*Feb 11 13:51:32.267: RIP: received packet with text authentication cisco

*Feb 11 13:51:32.271: RIP: received v2 triggered ack from 192.168.12.1 on Serial0/0/0

seq# 4

从上面的输出可以看出,在路由器 R2 上,虽然我们打开了  debug ip rip,但是由于采

用触发更新,所以并没有看到每 30 秒更新一次的信息,而是清除了路由表这件事件触发了

路由更新。而且所有的更新中都有“ triggered”的字样,同时在接收的更新中带有“ text

authentication

authentication”的字样,证明接口 s0/0/0 和 s0/0/1 启用了触发更新和明文认证。

(3) show ip rip database

该命令可以查看 RIP 数据库。

R2# show ip rip database

1.0.0.0/8 auto-summary

1.1.1.0/24

[1] via 192.168.12.1, 00:12:22 (permanent), Serial0/0/0

*  Triggered Routes:

- [1] via 192.168.12.1, Serial0/0/0

4.0.0.0/8 auto-summary

4.4.4.0/24

[2] via 192.168.23.3, 00:12:22 (permanent), Serial0/0/1

*  Triggered Routes:

- [2] via 192.168.23.3, Serial0/0/1

192.168.12.0/24 auto-summary

192.168.12.0/24 directly connected, Serial0/0/0

192.168.23.0/24 auto-summary

192.168.23.0/24 directly connected, Serial0/0/1

192.168.34.0/24 auto-summary

192.168.34.0/24

[1] via 192.168.23.3, 00:12:22 (permanent), Serial0/0/1

*  Triggered Routes:

- [1] via 192.168.23.3, Serial0/0/1

以上输出进一步说明了在 s0/0/0 和 s0/0/1 启用了触发更新。

(4) show run

R2# show run | begin router rip

router rip

version 2

timers basic 30 180  0 240

//由于触发更新,在配置中自动加入上面一行,且 hold down 计时器被设置为 0 0

network 192.168.12.0

network 192.168.23.0

no auto-summary

关于 MD5 认证,只需要在接口下声明认证模式为 MD5 即可,例如在 R1 上的配置如下:

R1(config)# key chain test //定义钥匙链

R1(config-keychain)# key 1

R1(config-keychain-key)# key-string cisco

R1(config)# interface s0/0/0

R1(config-if)# ip rip authentication mode md5 //认证模式为 MD5

R1(config-if)# ip rip authentication key-chain test

其他的配置和明文认证相同,这里不再赘述。当在 R2 上执行“ debug ip rip”时显示

类似如下的信息:

*Feb 11 14:04:36.851: RIP: sending  triggered request on Serial0/0/0 to 224.0.0.9

*Feb 11 14:04:36.855: RIP: sending  triggered request on Serial0/0/1 to 224.0.0.9

*Feb 11 14:04:36.867: RIP: sending triggered request on Serial0/0/0 to 224.0.0.9

*Feb 11 14:04:36.871: RIP: sending triggered request on Serial0/0/1 to 224.0.0.9

*Feb 11 14:04:36.871: RIP: send v2  triggered flush update to 192.168.12.1 on Serial0/0/0 with

no route

*Feb 11 14:04:36.875: RIP: start retransmit timer of 192.168.12.1

*Feb 11 14:04:36.875: RIP: send v2 triggered flush update to 192.168.23.3 on Serial0/0/1 with

no route

*Feb 11 14:04:36.879: RIP: start retransmit timer of 192.168.23.3

*Feb 11 14:04:36.927: RIP: received packet with  MD5 authentication

*Feb 11 14:04:36.931: RIP: received v2 triggered update from 192.168.23.3 on Serial0/0/1

*Feb 11 14:04:36.931: RIP: sending v2  ack to 192.168.23.3 via Serial0/0/1 (192.168.23.2),

flush, seq# 4

*Feb 11 14:04:36.935: 192.168.34.0/24 via 0.0.0.0 in 1 hops

*Feb 11 14:04:36.943: 4.4.4.0/24 via 0.0.0.0 in 2 hops

*Feb 11 14:04:36.947: RIP: received packet with MD5 authentication

*Feb 11 14:04:36.947: RIP: received v2 triggered update from 192.168.12.1 on Serial0/0/0

*Feb 11 14:04:36.951: RIP: sending v2 ack to 192.168.12.1 via Serial0/0/0 (192.168.12.2),

flush, seq# 3

*Feb 11 14:04:36.955: 1.1.1.0/24 via 0.0.0.0 in 1 hops

*Feb 11 14:04:36.959: RIP: received packet with MD5 authentication

*Feb 11 14:04:36.959: RIP: received v2 triggered update from 192.168.12.1 on Serial0/0/0

*Feb 11 14:04:36.963: RIP: sending v2 ack to 192.168.12.1 via Serial0/0/0 (192.168.12.2),

flush, seq# 4

*Feb 11 14:04:36.967: 1.1.1.0/24 via 0.0.0.0 in 1 hops

*Feb 11 14:04:36.967: RIP: received packet with MD5 authentication

*Feb 11 14:04:36.971: RIP: received v2 triggered ack from 192.168.12.1 on Serial0/0/0

flush seq# 5

*Feb 11 14:04:36.971: RIP: send v2 triggered update to 192.168.12.1 on Serial0/0/0

*Feb 11 14:04:36.975: RIP: build update entries

*Feb 11 14:04:36.975: route 191: 192.168.23.0/24 metric 1, tag 0

*Feb 11 14:04:36.979: route 194: 192.168.34.0/24 metric 2, tag 0

*Feb 11 14:04:36.979: route 197: 4.4.4.0/24 metric 3, tag 0

*Feb 11 14:04:36.983: RIP: Update contains 3 routes, start 191, end 201

*Feb 11 14:04:36.983: RIP: start retransmit timer of 192.168.12.1

*Feb 11 14:04:36.991: RIP: received packet with MD5 authentication

*Feb 11 14:04:36.991: RIP: received v2 triggered update from 192.168.23.3 on Serial0/0/1

*Feb 11 14:04:36.991: RIP: sending v2 ack to 192.168.23.3 via Serial0/0/1 (192.168.23.2),

flush, seq# 5

*Feb 11 14:04:36.999: 192.168.34.0/24 via 0.0.0.0 in 1 hops

*Feb 11 14:04:36.999: 4.4.4.0/24 via 0.0.0.0 in 2 hops

*Feb 11 14:04:37.003: RIP: received packet with MD5 authentication

*Feb 11 14:04:37.003: RIP: received v2 triggered ack from 192.168.23.3 on Serial0/0/1

flush seq# 4

*Feb 11 14:04:37.007: RIP: send v2 triggered update to 192.168.23.3 on Serial0/0/1

*Feb 11 14:04:37.007: RIP: build update entries

*Feb 11 14:04:37.011: route 189: 192.168.12.0/24 metric 1, tag 0

*Feb 11 14:04:37.015: route 200: 1.1.1.0/24 metric 2, tag 0

*Feb 11 14:04:37.015: RIP: Update contains 2 routes, start 189, end 201

*Feb 11 14:04:37.019: RIP: start retransmit timer of 192.168.23.3

*Feb 11 14:04:37.059: RIP: received packet with MD5 authentication

*Feb 11 14:04:37.059: RIP: received v2 triggered ack from 192.168.12.1 on Serial0/0/0

seq# 6

*Feb 11 14:04:37.067: RIP: received packet with MD5 authentication

*Feb 11 14:04:37.071: RIP: received v2 triggered ack from 192.168.23.3 on Serial0/0/1

seq# 5

以上输出信息表明采用了 MD5 认证和触发更新。

【技术要点 】

(1)在以太网接口下,不支持触发更新;

(2)触发更新需要协商,链路的两端都需要配置;

(3)在认证的过程中,如果定义多个 key ID,明文认证和 MD5 认证的匹配原则是不一

样的:

① 明文认证的匹配原则是:

A. 发送方发送最小Key ID的密钥

B. 不携带Key ID号码

C. 接收方会和所有 Key Chain 中的密钥匹配,如果匹配成功,则通过认证。

【实例 1 】

路由器 R1 有一个 Key ID,key1=cisco;

路由器 R2 有两个 Key ID,key1=ccie,key2=cisco

根据上面的原则,R1 认证失败,R2 认证成功,所以在 RIP 中,出现单边路由并不

稀奇。

② MD5 认证的匹配原则是:

A. 发送方发送最小Key ID的密钥

B. 携带Key ID号码

C. 接收方首先会查找是否有相同的Key ID,如果有,只匹配一次,决定认证是否

成功。如果没有该Key ID,只向下查找下一跳,匹配,认证成功;不匹配,认证失败。

【实例 2 】

路由器 R1 有三个 Key ID,key1=cisco,key3=ccie,key5=cisco ;

路由器 R2 有一个 Key ID,key2=cisco

根据上面的原则,R1 认证失败,R2 认证成功。

4.3.4 实验 7:浮动静态路由

1.实验目的

通过本实验可以掌握浮动静态路由原理、配置以及备份应用。

2.拓扑结构

实验拓扑如图 4-6 所示。

图 4-6 浮动静态路由

3.实验步骤

本实验通过修改静态路由的管理距离为 130,使得路由器选路的时候优先选择 RIP,而

静态路由作为备份。

(1)步骤 1:配置路由器 R1

R1(config)# ip route 2.2.2.0 255.255.255.0 192.168.12.2 130

//将静态路由的管理距离设置为 130

R1(config)# router rip

R1(config-router)# version 2

R1(config-router)# no auto-summary

R1(config-router)# network 1.0.0.0

R1(config-router)# network 192.168.21.0

(2)步骤 2:配置路由器 R2

R2(config)# ip route 1.1.1.0 255.255.255.0 192.168.12.1 130

R2(config)# router rip

R2(config-router)# version 2

R2(config-router)# no auto-summary

R2(config-router)# network 192.168.21.0

R2(config-router)# network 2.0.0.0

4.实验调试

(1)在 R1 上查看路由表:

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 192.168.12.0/24 is directly connected, Serial0/0/0

1.0.0.0/24 is subnetted, 1 subnets

C 1.1.1.0 is directly connected, Loopback0

2.0.0.0/24 is subnetted, 1 subnets

R 2.2.2.0 [120/1] via 192.168.21.2, 00:00:25, GigabitEthernet0/0

C 192.168.21.0/24 is directly connected, GigabitEthernet0/0

从以上输出可以看出,路由器将 RIP 的路由放入路由表中,因为 RIP 的管理距离为 120,

小于在静态路由中设定的 130,而静态路由处于备份的地位。

(2)在 R1 上将 g0/0 接口 shutdown,然后查看路由表:

R1(config)# interface gigabitEthernet 0/0

R1(config-if)# shutdown

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 192.168.12.0/24 is directly connected, Serial0/0/0

1.0.0.0/24 is subnetted, 1 subnets

C 1.1.1.0 is directly connected, Loopback0

2.0.0.0/24 is subnetted, 1 subnets

S 2.2.2.0 [130/0] via 192.168.12.2

以上输出说明,当主路由中断后,备份的静态路由被放入到路由表中,也很好地解释了

浮动静态路由作为备份的工作原理。

(3)在 R1 上将 g0/0 接口启动,然后查看路由表:

R1(config)# interface gigabitEthernet 0/0

R1(config-if)# no shutdown

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 192.168.12.0/24 is directly connected, Serial0/0/0

1.0.0.0/24 is subnetted, 1 subnets

C 1.1.1.0 is directly connected, Loopback0

2.0.0.0/24 is subnetted, 1 subnets

R 2.2.2.0 [120/1] via 192.168.21.2, 00:00:09, GigabitEthernet0/0

C 192.168.21.0/24 is directly connected, GigabitEthernet0/0

以上输出表明当主路由恢复后,浮动静态路由又恢复到备份的地位。

4.3.4 实验 8:ip default-network

1.实验目的

通过本实验可以掌握如何通过 ip default-network 向网络中注入一条默认路由。

2.拓扑结构

实验拓扑如图 4-7 所示。

图 4-7 ip default-network 向 RIP 网络中注入默认路由

3.实验步骤

(1)步骤 1:配置路由器 R1

R1(config)# router rip

R1(config-router)# version 2

R1(config-router)# no auto-summary

R1(config-router)# network 192.168.12.0

R1(config)# ip default-network 1.0.0.0

(2)步骤 2:配置路由器 R2

R2(config)# router rip

R2(config-router)# version 2

R2(config-router)# no auto-summary

R2(config-router)# network 192.168.12.0

R2(config-router)# network 2.0.0.0

4.实验调试

(1)在 R2 上查看路由表:

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 192.168.12.1 to network 0.0.0.0

//表明默认路由的网关为 192.168.12.1

C 192.168.12.0/24 is directly connected, Serial0/0/0

2.0.0.0/24 is subnetted, 1 subnets

C 2.2.2.0 is directly connected, Loopback0

R* 0.0.0.0/0 [120/1] via 192.168.12.1, 00:00:22, Serial0/0/0

从以上输出可以看出 R1 上的“ ip default-network”命令确实向 RIP 网络中注入一条

“ R* ”的默认路由。

(2)在 R2 上 ping 1.1.1.1;

R2# ping 1.1.1.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 12/14/16 ms

以上输出表明在路由器 R2 上可以 ping 通地址 1.1.1.1,虽然在 R1 的 RIP 进程中没有

通告该网络,也恰恰说明是默认路由起了作用。否则,因为在 R2 的路由表中没有 1.1.1.0

的路由条目,是不可能 ping 通的。

【技术要点 】

(1)ip default-network 后面的网络一定要是主类网络;

(2)ip default-network 后面的网络可以是直连的或者通过其它协议学到的网络。

4.4 RIP 命令汇总

表 4-2 列出了本章涉及到的主要的命令。

表 4-2 本章命令汇总

命令  作用

show ip route  查看路由表

show ip protocols  查看 IP 路由协议配置和统计信息

show ip rip database  查看 RIP 数据库

debug ip rip  动态查看 RIP 的更新过程

clear ip route *  清除路由表

router rip  启动 RIP 进程

network 通告网络

version  定义 RIP 的版本

no auto-summary  关闭自动汇总

ip rip send version  配置 RIP 发送的版本

ip rip receive version  配置 RIP 接收的版本

passive-interface  配置被动接口

neighbor  配置单播更新的目标

ip summary-address rip  配置 RIP 手工汇总

key chain 定义钥匙链

key  key-id 配置 Key ID

key-string 配置 Key ID 的密匙

ip rip triggered  配置触发更新

ip rip authentication mode  配置认证模式

ip rip authentication key-chain  配置认证使用的钥匙链

timers basic  配置更新的计时器

maximum-paths  配置等价路径的最大值

ip default-network  向网络中注入默认路由

RIP_第1张图片

RIP_第2张图片