(一) Route Maps
特性:
Route Maps类似于access lists,不同之处在于Route Maps可以改变Packets/Routes的部分属性。
用途:
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实现策略路由转发。
Redistribution发送Routes到Route Maps实现路由条目的过滤。
配置说明:
Route Maps如果没有指定Action及Sequence Number属性,默认:
Action: permit
Sequence Number: 10
且Sequence Number不会自动增加。
即如果在使用Route Maps语句时不指定Sequence Number,则覆盖Sequence Number为10的默认条目。
Route Maps Deny Action:
Redistribution: 特定路由条目不会被重分布。
Policy Routing: 特定的Packets不会按策略路由转发,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)可以使用Standard及Extended ACL.
(3)全局配置ip local policy route-map sense可将策略路由应用于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 0.0.0.255
access-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 any
access-list 105 permit tcp 172.16.1.0 0.0.0.255 eq ftp-data any
access-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 0.0.0.255
access-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:如果没有第一个route-map条目,router本身的Packets及OSPF的Packets都会由于后两个route-map语句被转发到错误的地址。 |