CCNA,RIP协议

cisco CCNA RIP 协议

路由信息协议 RIP

深圳职业技术学院计算机系网络专业

© 2006, Shenzhen Polytechnic. All rights reserved.

cisco CCNA RIP 协议

教学目标( 教学目标( Objectives )

1. 动态路由(Dynamic Routing) 动态路由( ) 2. 距离向量路由协议( Distance Vector Protocol) 距离向量路由协议( ) 3.管理距离和度量值 管理距离和度量值 ( Administrative Distance and Metric) ) 4. 路由信息协议(RIP) 路由信息协议( ) 5. RIP配置(Configing RIP) 配置( 配置 ) 6. 路由环路( Routing Loops ) 路由环路(

© 2006, Shenzhen Polytechnic. All rights reserved.

cisco CCNA RIP 协议

路由器怎样传递数据包 (How routers route packets from source to destination )

1.拆包 拆包(remove the data link layer address) 拆包 2.查表 查表(refer to the routing table) 查表 3.打包 打包(encapsulating a new frame) 打包 4.转发 转发(forwarding the packet) 转发

© 2006, Shenzhen Polytechnic. All rights reserved.

cisco CCNA RIP 协议

动态路由(Dynamic Routing) 动态路由( )

适应拓扑结构的变化 Adapting to topology change© 2006, Shenzhen Polytechnic. All rights reserved.4

cisco CCNA RIP 协议

动态路由协议分类 (Classes of Dynamic Routing Protocols) )

Distance Vector:rip : 距离向量

B C D A

Hybrid Routing:eigrp 混合路由B C D A

Link State:ospf 链路状态

如何衡量路径的好坏呢© 2006, Shenzhen Polytechnic. All rights reserved.

?5

cisco CCNA RIP 协议

管理距离( 管理距离(Administrative Distance) )管理距离用于衡量其作为路由信息源的可信度。 管理距离用于衡量其作为路由信息源的可信度。 A measure of the reliability of the route 管理距离越低 路由选择协议的可信度越高 管理距离越低，路由选择协议的可信度越高。I need to send a packet to Network E. Both router B and C will get it there. Which route is best? Router A

A lower value for the administrative distance indicates the more reliable route

Router B

RIP Administrative Distance=120

IGRP Administrative Distance=100

E© 2006, Shenzhen Polytechnic. All rights reserved.

Router C

Router D6

cisco CCNA RIP 协议

默认管理距离 (Default Administrative Distance) )路由选择协议 Routing Protocol 直连的接口 (connected) static EIGRP IGRP OSPF RIP 管理距离 AD 0 1 90 100 110 120

© 2006, Shenzhen Polytechnic. All rights reserved.

cisco CCNA RIP 协议

度量值( 度量值( Metric )度量值越小 路径就越好 度量值越小，路径就越好。 A lower value for the metric indicates the more reliable route 度量因素( 度量因素(factors for metric): ): 带宽( 带宽(Bandwidth) ) 延迟( 延迟(Delay) ) 负载( 负载(Load) ) 可靠性( ) 可靠性(Reliability) 跳数( 跳数(Hop Count) )

© 2006, Shenzhen Polytechnic. All rights reserved.

cisco CCNA RIP 协议

用度量值选择最佳路径 (Selecting Best Route with Metrics) )A 56 RIP Hop count 跳数 T1 56 IGRP Bandwidth Delay Load Reliabil

ity MTU T1 B

© 2006, Shenzhen Polytechnic. All rights reserved.

cisco CCNA RIP 协议

Case Study 1根据管理距离和度量值对路径由好到坏排序： 根据管理距离和度量值对路径由好到坏排序：

1. [120/2] 2. [120/2] 3. [100/35556] 4. [90/1288] 5. [90/19999]© 2006, Shenzhen Polytechnic. All rights reserved.

4 5 3 2 110

cisco CCNA RIP 协议

距离向量路由协议 (Distance Vector Routing Protocols) )

B C Distance—多远 多远 Vector—方向 方向 A

D

D

C

B

A

Routing Table

Routing Table

Routing Table

Routing Table

Pass periodic copies of routing table to neighbor routers and accumulate distance vectors 定期拷贝路由表给邻居路由器， 定期拷贝路由表给邻居路由器，并累积向量© 2006, Shenzhen Polytechnic. All rights reserved.11

cisco CCNA RIP 协议

距离向量—发现路由 距离向量 发现路由 (Distance Vector— Discovering Routes) )10.1.0.0E0

10.2.0.0 AS0 S0

10.3.0.0 BS1 S0

10.4.0.0 CE0

Routing Table 10.1.0.0 10.2.0.0 E0 S0 0 0

Routing Table 10.2.0.0 10.3.0.0 S0 S1 0 0

Routing Table 10.3.0.0 10.4.0.0 S0 E0 0 0

路由器从邻居那里发现到目的的最佳路径 Routers discover the best path to destinations from each neighbor© 2006, Shenzhen Polytechnic. All rights reserved.12

cisco CCNA RIP 协议

距离向量—发现路由 距离向量 发现路由 (Distance Vector— Discovering Routes)10.1.0.0E0

10.2.0.0 AS0 S0

10.3.0.0 BS1 S0

10.4.0.0 CE0

Routing Table 10.1.0.0 10.2.0.0 10.3.0.0 E0 S0 S0 0 0 1

Routing Table 10.2.0.0 10.3.0.0 10.4.0.0 10.1.0.0 S0 S1 S1 S0 0 0 1 1

Routing Table 10.3.0.0 10.4.0.0 10.2.0.0 S0 E0 S0 0 0 1

路由器从邻居那里发现到目的的最佳路径 Routers discover the best path to destinations from each neighbor© 2006, Shenzhen Polytechnic. All rights reserved.13

cisco CCNA RIP 协议

距离向量—发现路由 距离向量 发现路由 (Distance Vector— Discovering Routes) )10.1.0.0E0

10.2.0.0 AS0 S0

10.3.0.0 BS1 S0

10.4.0.0 CE0

Routing Table 10.1.0.0 10.2.0.0 10.3.0.0 10.4.0.0 E0 S0 S0 S0 0 0 1 2

Routing Table 10.2.0.0 10.3.0.0 10.4.0.0 10.1.0.0 S0 S1 S1 S0 0 0 1 1

Routing Table 10.3.0.0 10.4.0.0 10.2.0.0 10.1.0.0 S0 E0 S0 S0 0 0 1 2

路由器从邻居那里发现到目的的最佳路径 Routers discover the best path to destinations from each neighbor© 2006, Shenzhen Polytechnic. All rights reserved.14

cisco CCNA RIP 协议

路由环路( 路由环路(Routing Loop )10.1.0.0E0

10.2.0.0 AS0 S0

10.3.0.0 BS1 S0

10.4.0.0 CE0

X

到达网络0.4.0.0的数据包在 的数据包在A,B,C之间无限传递 到达网络 的数据包在 之间无限传递 Packets for network 10.4.0.0 bounce between routers A, B, and C© 2006, Shenzhen Polytechnic. All rights reserved.15

cisco CCNA RIP 协议

解决方案： 解决方案：定义最大跳数 (Solution: Defining a Maximum) )10.1.0.0E0

10.2.0.0 AS0 S0

10.3.0.0 BS1 S0

10.4.0.0 CE0

X

Routing Table 10.1.0.0 10.2.0.0 10.3.0.0 10.4.0.0 E0 S0 S0 S0 1 16 0 0

Routing Table 10.2.0.0 10.3.0.0 10.4.0.0 10.1.0.0 S0 S1 S1 S0 16 1 0 0

Rout

ing Table 10.3.0.0 10.4.0.0 10.2.0.0 10.1.0.0 S0 S0 S0 S0 0 16 1 2

通过定义最大跳数来阻止路由无限循环 Define a limit on the number of hops to prevent infinite loops© 2006, Shenzhen Polytechnic. All rights reserved.16

cisco CCNA RIP 协议

解决方案： 解决方案：水平分割 (Solution: Split Horizon) )10.1.0.0E0

10.2.0.0 AS0

10.3.0.0 BS1

10.4.0.0S0

X

S0

X

C

E0

X

路由信息不能够发回其起源的路由器 It is never useful to send information about a route back in the direction from which the original packet came© 2006, Shenzhen Polytechnic. All rights reserved.17

cisco CCNA RIP 协议

解决方案： 解决方案：路由毒化 Solution: Route Poisoning10.1.0.0E0

10.2.0.0 AS0 S0

10.3.0.0 BS1 S0

10.4.0.0 CE0

X

Routing Table 10.1.0.0 10.2.0.0 10.3.0.0 10.4.0.0 E0 S0 S0 S0 1 2 0 0

Routing Table 10.2.0.0 10.3.0.0 10.4.0.0 10.1.0.0 S0 S1 S1 E1 1 2 0 0

Routing Table 10.3.0.0 10.4.0.0 10.2.0.0 10.1.0.0 S0 0

S0 Infinity 1 S0 S0 2

路由器马上将down的路由设为不可达(如，16跳) 的路由设为不可达( 路由器马上将 的路由设为不可达 跳 Routers set the distance of routes that have gone down to infinity© 2006, Shenzhen Polytechnic. All rights reserved.18

cisco CCNA RIP 协议

解决方案： 解决方案：毒化反转 ) (Solution: Poison Reverse)10.1.0.0E0

10.2.0.0 AS0 S0

10.3.0.0 BS1 S0

10.4.0.0 CE0

X

Poison ReverseRouting Table 10.1.0.0 10.2.0.0 10.3.0.0 10.4.0.0 E0 S0 S0 S0 1 2 0 0 Routing Table 10.2.0.0 10.3.0.0 10.4.0.0 10.1.0.0 S0 S1 S1 E1 2 0 0Possibly Down

Routing Table 10.3.0.0 10.4.0.0 10.2.0.0 10.1.0.0 S0 0

S0 Infinity 1 S0 S0 2

毒化反转和水平分割一起使用 Poison Reverse overrides split horizon© 2006, Shenzhen Polytechnic. All rights reserved.19