This sample configuration statically routes both IP and IPX using PPP with CHAP authentication over an asynchronous modem connected to the auxiliary port. With static routes between the two routers, there is no need for the routers to exchange routing updates and the phone line activates only when traffic demands. This is known as dial-on-demand routing (DDR).

An alternative to DDR using static routes is DDR using a snapshot routing protocol. Snapshot routing allows routes to be automatically exchanged during a defined time interval instead of burdening a network administrator with the chore of manually maintaining static routes. Although the phone line must be activated for each snapshot routing update, the duration and frequency of the snapshot interval can be configured such that any phone costs due to dynamic routing are relatively negligible compared with the benefits of simplified network administration.

Get A Configuration Using Snapshot Routing (recommended)
Faxback Doc #0557

Info On PPP Faxback Doc #ppp

Info On Snapshot Routing Faxback Doc #snapshot

Info On IP Unnumbered Faxback Doc #ip_unnum

Before You Begin

Get The IOS Async Command Glossary. Faxback Doc #0552 Detailed descriptions of all IOS commands used in Async configurations. Also provides links to the IOS Command Reference if more information is required

Get The IOS Command Line Interface Tutorial Faxback Doc #ios_tutorial Instructions on configuring an IOS router using the command line interface

Note: Commands followed by a <*> are on by default and do not have to be configured. The "!" marks that appear in the configuration are automatically entered by the router and function as line separators for easier reading.

Atlanta Router Configuration
In IOS "show running-config" format

version 11.2 <*>
service udp-small-servers <*>
service tcp-small-servers <*>
!
hostname Atlanta
!
enable secret cisco
!
username Boston password gocisco1
ip subnet-zero
no ip domain-lookup
ipx routing 0000.0caa.1111
chat-script rstmdm "" "AT&FS0=1&B1&C1&D2&H1&K1&M4&R2" OK
chat-script dialnum ABORT ERROR ABORT BUSY "" "ATDT \T" TIMEOUT 60 CONNECT
!
interface Ethernet0
 ip address 10.1.1.1 255.0.0.0
 ipx network 100
!
interface Serial0
 no ip address <*>
 shutdown <*>
!
interface Async1
 no ip address <*>
 encapsulation ppp
 async default routing
 async mode dedicated
 dialer in-band
 dialer rotary-group 0
 no cdp enable <*>
!
interface Dialer0
 ip unnumbered Ethernet0
 ip tcp header-compression passive
 encapsulation ppp
 ipx network AAAA
 dialer in-band
 dialer map ipx AAAA.0000.0cbb.2222 name Boston 16175553333
 dialer map ip 20.1.1.1 name Boston 16175553333
 dialer-group 1
 no cdp enable <*>
 ppp authentication chap
!
ip classless
ip route 20.1.1.1 255.255.255.255 Dialer0
ip route 20.0.0.0 255.0.0.0 20.1.1.1
!
ipx route 2000 AAAA.0000.0cbb.2222
ipx route 200 AAAA.0000.0cbb.2222
!
ipx sap 4 BostonFS 2000.0000.0000.0001 451 2
!
dialer-list 1 protocol ip permit
dialer-list 1 protocol ipx permit
!
line con 0
 password console
 login
line aux 0
 script dialer dialnum
 script reset rstmdm
 modem InOut
 transport input all
 rxspeed 38400
 txspeed 38400
 stopbits 1
 flowcontrol hardware
line vty 0 4
 password telnet
 login
!
end <*>

Boston Router Configuration
In IOS "show running-config" format

version 11.2 <*>
service udp-small-servers <*>
service tcp-small-servers <*>
!
hostname Boston
!
enable secret cisco
!
username Atlanta password gocisco1
ip subnet-zero
no ip domain-lookup
ipx routing 0000.0cbb.2222
chat-script rstmdm "" "AT&FS0=1&B1&C1&D2&H1&K1&M4&R2" OK
chat-script dialnum ABORT ERROR ABORT BUSY "" "ATDT \T" TIMEOUT 60 CONNECT
!
interface Ethernet0
 ip address 20.1.1.1 255.0.0.0
 ipx network 200
!
interface Serial0
 no ip address <*>
 shutdown <*>
!
interface Async1
 no ip address <*>
 encapsulation ppp
 async default routing
 async mode dedicated
 dialer in-band
 dialer rotary-group 0
 no cdp enable <*>
!
interface Dialer0
 ip unnumbered Ethernet0
 encapsulation ppp
 ipx network AAAA
 dialer in-band
 dialer map ip 10.1.1.1 name Atlanta 14045551111
 dialer map ipx AAAA.0000.0caa.1111 name Atlanta 14045551111
 dialer-group 1
 no cdp enable <*>
 ppp authentication chap
!
ip classless
ip route 10.1.1.1 255.255.255.255 Dialer0
ip route 10.0.0.0 255.0.0.0 10.1.1.1
!
ipx route 1000 AAAA.0000.0caa.1111
ipx route 100 AAAA.0000.0caa.1111
!
ipx sap 4 AtlantaFS 1000.0000.0000.0001 451 2
!
dialer-list 1 protocol ip permit
dialer-list 1 protocol ipx permit
!
line con 0
 password console
 login
line aux 0
 script dialer dialnum
 script reset rstmdm
 modem InOut
 transport input all
 rxspeed 38400
 txspeed 38400
 stopbits 1
 flowcontrol hardware
line vty 0 4
 password telnet
 login
!
end <*>

After You've Tried

You've tried the configuration and it doesn't work. Help is available!

Get IOS Router Async Troubleshooting Assistance Faxback Doc #async_ts

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