用Route Map实现多ISP Internet接入问题请高手赐教

R2:为公网接入点,为了保证能一天24小时公司的网络能上INTERNET,现接入两家供应商的线路来连接INTERNET,

即然接入了两家供应商线路,当然希望两条线路能同时启用做到负载均衡的目的,当一条线路出了问题,客户端还可以走另一条线路出到INTERNET,现在要在R2路由器上做相关设置以达到我们所需求.以下是在R2上的配置如下:

R2#show run

Building configuration...

Current configuration : 1449 bytes

!

version 12.4

service timestamps debug datetime msec

service timestamps log datetime msec

no service password-encryption

hostname R2

boot-start-marker

boot-end-marker

no aaa new-model

memory-size iomem 5

ip cef

!

interface Serial0/0

ip address 150.17.232.2 255.255.254.0

ip nat inside

ip virtual-reassembly

serial restart-delay 0

interface Serial0/1

ip address 192.168.2.1 255.255.255.0

ip nat outside

interface Serial0/2

ip address 172.16.20.1 255.255.0.0

!

ip http server

no ip http secure-server

ip nat inside source route-map isp1 interface Serial0/1 overload

ip nat inside source route-map isp2 interface Serial0/2 overload

access-list 100 permit ip 150.17.232.0 0.0.0.255 192.168.2.0 0.0.0.255

access-list 101 permit ip 150.17.232.0 0.0.0.255 any

route-map isp2 permit 10

match ip address 101

match interface Serial0/2

route-map isp1 permit 10

match ip address 100

match interface Serial0/1

control-plane

line con 0

exec-timeout 0 0

logging synchronous

line aux 0

line vty 0 4

login

问:用router-map 与直接用PAT它们之间有什么区别?

是不是用router-map能够自动做负载均衡,而用PAT则只能走一条线路呢?

第一种方法用router-map来配置

ip nat inside source route-map isp1 interface Serial0/1 overload

ip nat inside source route-map isp2 interface Serial0/2 overload

!

access-list 100 permit ip 150.17.232.0 0.0.0.255 192.168.2.0 0.0.0.255

access-list 101 permit ip 150.17.232.0 0.0.0.255 any

route-map isp2 permit 10

match ip address 101

match interface Serial0/2

route-map isp1 permit 10

match ip address 100

match interface Serial0/1