网络设备安装与调试chp25路由优化课件

1、路由优化 Route Optimization 教学目标（ Objectives ）1. 被动接口（Passive Interface）2.分布列表（ Distribute List ）3.前缀列表（ Prefix List）4.偏移列表（Offset List）第一节 被动接口和分布列表控制路由更新（Controlling Routing Updates）Passive interfaceStatic routesDefault routeRoute mapsDistribute listsPrefix lists被动接口（Passive Interfaces）对于特定的协议，被动接口阻止发

2、送或者接收路由更新Passive interfaces prevent routing updates from being sent and/or received for a specified protocol. RIP可以接收更新，但是不能发送更新RIP interfaces listen but will not send updates. OSPF和EIGRP不接受也不发送更新，因而不能形成邻居关系OSPF and EIGRP interfaces do not listen for or send updates and therefore no neighbor adjacen

3、cies can be established.passive-interface default Command大的企业可能配置多个被动接口，在一些网络中，可能要使用200多次passive-interface命令。Large enterprise may need to set multiple interfaces as passive.In some networks, this could mean coding 200 or more passive-interface statements. passive-interface default命令把参与相应路由协议的所有接口配置为

4、被动接口。The passive-interface default command sets all interfaces as passive by default.需要参与路由更新的接口通过命令passive-interface default 激活。Interfaces on which adjacencies updates are desired can be set as active with the passive-interface default command.使用passive-interface命令（Using the passive-interface Comma

5、nd）使用分布列表（Using Distribute Lists）分布列表允许ACL应用到路由更新中，达到过滤的目的Distribute list allows an ACL to be applied to routing updates for filtering purposes.过滤入向更新（Filter Incoming Routing Updates）Router(config-router)#distribute-list access-list-number | name route-map map-tag in interface-type interface-numberP

6、arameterDescriptionaccess-list-number | nameSpecifies the standard access list number or name.map-tag(Optional) Specifies the name of the route map that defines which networks are to be installed in the routing table and which are to be filtered from the routing table. This argument is supported by

7、OSPFonly.inApplies the access list to incoming routing erface-type interface-number(Optional) Specifies the interface type and number from which updates are filtered.过滤出向更新（Filter Outgoing Routing Updates）Router(config-router)#distribute-list access-list-number | name out interface-name |

8、 routing-process routing-process parameter ParameterDescriptionaccess-list-number | nameSpecifies the standard access list number or name.outApplies the access list to outgoing routing erface-name(Optional) Specifies the name of the interface out of which updates are filtered. routing-pro

9、cess(Optional) Specifies the name of the routing process, or the keyword static or connected, that is being redistributed and from which updates are filtered.routing-process parameter(Optional) Specifies a routing process parameter, such as the AS number of the routing process.distribute-list out Or

10、 inFilter outgoing routing updatesR1(config-router)# distribute-list 1 outFilter incoming routing updatesR1R1R1(config-router)# distribute-list 2 in使用接口过滤，隐藏了网络Hides network using interface filtering用分布列表过滤路由更新（Filtering Routing Updates Using Distribute List）Case Study 1：配置被动接口和分布列表

11、1.R1发送EIGRP更新时，过滤172.16.X.0路由,其中X为奇数的路由条目过滤2.在R2上把EIGRP重分布到OSPF时，包含172.16.X.0，其中X能被4整除和路由3.在R3上，只希望收到和两条路由条目第二节 前缀列表使用前缀列表（Using Prefix Lists）在很多路由过滤命令中，ACL被前缀列表替代。Prefix lists can be used as an alternative to access lists in many route filtering commands.前缀列表特征（Prefix

12、list characteristics include）:对于大的列表，装载和查询效率比ACL显著提升A significant performance improvement over ACLs in loading and route lookup of large lists. 支持增量修改（Support for incremental modifications.）在指定掩码长度范围方面具有更大的灵活性Greater flexibility in specifying subnet mask ranges.配置前缀列表（Configure a Prefix List）Router(

13、config)#ip prefix-list list-name | list-number seq seq-value deny | permit network/length ge ge-value le le-valueParameterDescriptionlist-nameThe name of the prefix list that will be created (it is case sensitive).list-numberThe number of the prefix list that will be created.seq seq-valueDefault seq

14、uence numbers are in increments of 5 (5, 10, 15, and so on).deny | permitThe action taken when a match is work/lengthThe prefix to be matched and the length of the prefix. ge ge-valueThe range is assumed to be from ge-value to 32 if only the ge attribute is specified.le le-valueThe range is assumed

15、to be from length to le-value if only the le attribute is specified.配置前缀列表（Configure a Prefix List）全局模式下，使用no ip prefix-list 命令删除前缀列表Use the no ip prefix-list list-name global configuration command to delete a prefix list.全局命令ip prefix-list list-name description text 可以增加或者删除前缀列表描述The ip prefix-list

16、 list-name description text global configuration command can be used to add or delete a text description for a prefix list.提示（Tip）:为了达到最佳性能，最常用到的陈述应该使用较低的序号。For best performance, the most frequently processed prefix list statements should be configured with the lowest sequence numbers. 前缀列表匹配规则（Pref

17、ix List Matching rules）精确匹配范围匹配没有le或ge匹配（Prefix List Matching without le or ge）类似没有通配符掩码的IP ACL有le或ge匹配（Prefix List Matching with le or ge）前缀列表匹配实例（Example:Prefix List Matching）ip prefix-list test1 seq 5 permit /0 ge 32 匹配所有主机路由ip prefix-list test2 seq 10 permit /0 le 32 匹配所有路由ip prefi

18、x-list test4 seq 20 permit /1 ge 8 le 8 匹配A类地址ip prefix-list test5 seq 25 permit /2 ge 16 le 16 匹配B类地址ip prefix-list test6 seq 30 permit /3 ge 24 le 24 匹配C类地址ip prefix-list test7 seq 35 permit /16 le 20ip prefix-list test8 seq 40 permit /16 ge 20Case St

19、udy 2：配置前缀列表/24.1.2s0/0s0/0R1R2Lo0:/24Lo1:/27Lo2:3/28Lo3:5/29Lo4:7/30Lo0:/24.2.3s0/1R3/24s0/1area0area1网络运行OSPF路由协议，在R1上重分布直连路由，对主类地址/16网络的子网路由进行控制，使得：1.直连路由掩码长度为24-28的，重分布时设置路由类型为1,种子度量值为1002.直连路由掩码长度大于29的，重

20、分布时设置路由类型为2,种子度量值为200，路由Tag为2003.重分布其他直连路由时不做控制。Case Study 2：配置前缀列表R1(config)#ip prefix-list CONN1 seq 5 permit /16 ge 24 le 28R1(config)#ip prefix-list CONN2 seq 5 permit /16 ge 29R1(config)#route-map CONN permit 10R1(config-route-map)#match ip address prefix-list CONN1R1(config

21、-route-map)#set metric 100R1(config-route-map)#set metric-type type-1R1(config)#route-map CONN permit 20R1(config-route-map)#match ip address prefix-list CONN2R1(config-route-map)#set metric 200R1(config-route-map)#set tag 200R1(config)#route-map CONN permit 30R1(config)#router ospf 1R1(config-route

22、r)#redistribute connected subnets route-map CONN第三节 偏移列表用偏移列表控制路径（Path Control Using Offset Lists）偏移列表用于出站或者入站方向增加EIGRP或者RIP路由条目的度量值。 An offset list is the mechanism for increasing incoming and outgoing metrics to routes learned via EIGRP or RIP.使用命令offset-list创建偏移列表。To create an offset-list, use th

23、e offset-list router configuration command.只适用于距离向量路由协议(Distance Vector Routing Protocol only)定义偏移列表（Defining an Offset-List）Router(config-router)#offset-list access-list-number | access-list-name in | out offset interface-type interface-numberParameterDescriptionaccess-list-number | access-list-name Standard access list number or name to be applied. Access list number 0 indicates all access lists. in Applies the access list to incoming metrics. outApplies the access list to outgoing metrics. offset Positive offset to be applied to metrics. If the offset is 0, no action is takenin