路由过滤号令详解route-map[网络技术]

（一）Route Maps 　　特点:

　　Route Maps近似于access lists,差别之处在于Route Maps可以改变Packets/Routes的部份属性.

　　用处:

　　Route Maps主要用于Redistribution和Policy Routing及BGP的实现.

　　实现:

　　Policy Routing发送Packets到Route Maps实现战略路由转发.

　　Redistribution发送Routes到Route Maps实现路由条目的过滤.

　　配置阐明:

　　Route Maps假如没有指定Action及Sequence Number属性,默许:

　　Action:   permit

　　Sequence Number:   10

　　且Sequence Number不会自动增添.

　　即假如在利用Route Maps语句时不指定Sequence Number,则覆盖Sequence Number为10的默许条目.

　　Route Maps Deny Action:

　　Redistribution: 特定路由条目不会被重分布.

　　Policy Routing: 特定的Packets不会按战略路由转发,但会梗概正常的路由表条目转发.

　　Case Study:Policy Routing

　　注:（1）Policy Routing只影响入流量.

　　（2）可以利用Standard及Extended ACL.

　　（3）全局配置ip local policy route-map sense可将战略路由利用于Router本身发送的Packets.

<1> Standard ACL

interface Serial 0   ip address 172.16.5.1 255.255.255.0   ip policy route-map sense!access-list 1 permit 172.16.6.0 0.0.0.255access-list 2 permit 172.16.7.0 0.0.0.255!route-map sense permit 10   match ip address 1   set ip next-hop 172.16.4.2!route-map sense permit 20   match ip address 2   set ip next-hop 172.16.4.3

<2> Extended ACL
 

interface Ethernet 0   ip address 172.16.1.4 255.255.255.0   ip policy route-map sense!access-list 105 permit tcp 172.16.1.0 0.0.0.255 eq ftp anyaccess-list 105 permit tcp 172.16.1.0 0.0.0.255 eq ftp-data anyaccess-list 106 permit tcp 172.16.1.0 0.0.0.255 eq telnet any!route-map sense permit 10   match ip address 105   set ip next-hop 172.16.2.1!route-map sense permit 20   match ip address 106   set ip next-hop 172.16.3.1

<3> Length of the Packets
 

interface Ethernet0   ip address 172.16.1.4 255.255.255.0   ip policy route-map sense!route-map sense permit 10   match length 1000 1600   set ip next-hop 172.16.2.1!route-map sense permit 20   match length 0 400   set ip next-hop 172.16.3.1

<4> Router's Packets
 

interface Ethernet0   ip address 172.16.1.4 255.255.255.0   ip policy route-map sense!ip local policy route-map sense!access-list 120 permit ip any 172.16.1.0 0.0.0.255access-list 120 permit ospf any any!route-map sense permit 10   match ip address 120!route-map sense permit 20   match length 1000 1600   set ip next-hop 172.16.2.1!route-map sense permit 30   match length 0 400   set ip next-hop 172.16.3.1

注:假如没有第一个route-map条目,router本身的Packets及OSPF的Packets城市由于后两个route-map语句被转发到错误的地址.
 

Case Study:Policy Routing and Quality of Service Routing 　　Policy Routing结合ip包头的Precedence和Type of Service（TOS）可以实现基于QOS的战略路由.

　　注:Precedence和TOS的配置既可以利用Number字段,也可以利用Keyword.

set ip precedence-------------------------------------Bits     Number     Keyword000        0        routine001        1        priority010        2        immediate011        3        flash100        4        flash-override101        5        critical110        6        internet111        7        network-------------------------------------set ip tos-------------------------------------Bits     Number     Keyword0000       0        normal0001       1        min-monetary-cost0010       2        max-reliability0100       4        max-throughput1000       8        min-delay-------------------------------------interface Serial0   ip address 10.1.18.67 255.255.255.252   ip policy route-map sense!interface Serial1   ip address 10.34.16.83.255.255.255.252   ip policy route-map sense!access-list 1 permit 172.16.0.0 0.0.255.255access-list 110 permit tcp any eq www any!route-map sense permit 10   match ip address 1 110   set ip precedence critical!route-map sense permit 20   set ip tos 10   set ip precedence priorityCase Study: Route Tagging

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