Cisco路由器配置DDR拨号


dial-on demand routing (ddr)是用公共电话网提供了网络连接 。通常的,广域网大多数使用专线连接的,路由器连接到类似MODEM OR ISDNTAS 的数据终端DCE设备上,他们支持同步V.25BITS协议,你可以用SCRIPTS AND DIALER命令设定拨号串 。
DDR比较适用于用户对数率要求不高,偶然有数据传输或只是在特定时候传输数据,比如银行每晚传送报表等等情况下 。
当一个感爱好的包到达路由器时,产生一个DDR请求,路由器发送呼叫建立信息给指定的串口的DCE设备,这个呼叫就把本地的和远程的设备连接起来,一旦没有数据传输,空闲时间开始记时,超过设置的记时时间,连接终止 。DDR现在都用静态路由来传输数据,避免路由交换引起的DDR拨号 。和XNS可以通过DDR路由寻址,同步串口,异步串口和ISDN端口可以配置成到一个或多个目的地的DDR连接 。
下面是一个典型的DDR连接:
在配置DDR过程中,我们可以把一个或几个物理端口配置成一个逻辑拨号接口,他可以是同步V.25方式,同步DYR启动拨号或异步CHATSCRIPT方式 。
具体配置:

interface serial 0
ip address 131.108.126.1 255.255.255.0
dialer in-band
dialer-group 1
!
dialer map ip 131.108.126.2 55551234
!
dialer idle-timeout 300
dialer backup example
A) 同步V.25bits方式
configuration for routerA:
interface serial 10:0
backup delay 0 10
backup interface serial 110
ip address 16.217.30.2 255.255.255.252
!
interface serial 110
ip address 16.30.16.81 255.255.255.25.0
encapsulation ppp
dialer in-band
dialer string 8292
dialer-group 1
pulse-time 1
!
dilar-list 1 protocol ip permit
B) 辅助口作拨号备份
configuration for routerA:
chat-script mydial “””atdt 8292” timeout 60 “connect”
!
interface serial 0
backup delay 0 0
backup interface async1
ip address 16.3.1.1 255.255.255.0
encapsulation ppp
!
interface async1
ip address 16.3.2.1 255.255.255.0
encapsulation ppp
keepalive 9
async default routing
async dynamic address
async dynamic routing
async mode dedicated
dialer string 8292
dialer-group 1
!
dialer-list 1 protocol ip permit
!
line aux 0
script dialer mydial
modeinout
transport output none
stopbits 1
flowcontrol hardware
speed 9600
subinterface example (frame realay)
configuration for routerA:
interface serial 0
encapsulation frame-relay
interface serial 0.1 multipoint
ip address 11.10.11.1 255.255.255.0
frame-relay interface-dlci 41
frame-relay interface-dlci42
configuration for routerC:
interface serial 0
encapsulation frame-relay
interface serial 0.1 point-point
ip address 11.10.16.2 255.255.255.0
frame-realy interface-dlci 46
configuration for routerB:
interface serial 0
encapsulation frame-relay
interface serial 0.1 multipoint
ip address 11.10.11.3 255.255.255.0
frame-relay interface-dlci 43
frame-relay interface-dlci 44
!
interface serial 0.2 point-point
ip address 11.10.13.1 255.255.255.0
frame-realy interface-dlci 48
frame relay switching example
configuration for routerA:
frame-relay switching
no ip address
frame-relay encapsulation
frame-relay route 163 tun0 43
frame-relay intf-type dce
!
interface serial0
ip address 131.108.100.1 255.255.255.0
!
interface tu 0
tunnel source serial 1
tunnel destintion 131.108.13.2

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