This sample configuration dynamically routes both IP and IPX between two Cisco IOS routers using snapshot IP RIP, snapshot IPX RIP/SAP, and PPP with CHAP authentication over an ISDN link. With snapshot routing, IP route updates and IPX route and service updates are exchanged between routers during a user configured interval rather than the constant periodic exchange required of normal IP RIP and IPX RIP/SAP. Aside from this snapshot interval, the ISDN line activates only when traffic demands. This is known as dial-on-demand routing (DDR). In contrast, the periodic exchange of normal RIP would force the ISDN line to be permanently active, potentially resulting in high ISDN costs.

An alternative to DDR using a snapshot routing protocol is DDR using static routes. Routing tables are statically created by the network administrator eliminating the need for snapshot routing exchanges. For smaller networks, static routes may suffice. However, for larger networks, manually maintaining static routing tables on every router can be an administrative chore. Fortunately, the duration and frequency of the snapshot routing interval can be configured such that any ISDN costs due to dynamic routing are relatively negligible compared with the benefits of simplified network administration.

Get A DDR Configuration Using Static Routes if static routing is still desired.
Faxback Doc #0514

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 ISDN Command Glossary. Faxback Doc #0551 Detailed descriptions of all IOS commands used in ISDN 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
isdn switch-type basic-ni1
!
interface Ethernet0
 ip address 10.1.1.1 255.0.0.0
 ipx network 100 encapsulation SAP
 ipx network 101 encapsulation NOVELL-ETHER secondary
!
interface BRI0
 no ip address <*>
 encapsulation ppp
 dialer rotary-group 0
 isdn spid1 014045551111000 5551111
 isdn spid2 014045552222000 5552222
 no fair-queue <*>
 no cdp enable <*>
!
interface Dialer0
 ip unnumbered Ethernet0
 encapsulation ppp
 ipx network AAAA
 no ipx route-cache
 ipx watchdog-spoof
 dialer in-band
 dialer idle-timeout 300
 dialer map snapshot 1 name Boston speed 56
 dialer map ipx AAAA.0000.0cbb.2222 name Boston speed 56 broadcast 16175553333
 dialer map ipx AAAA.0000.0cbb.2222 name Boston speed 56 broadcast 16175554444
 dialer map ip 20.1.1.1 name Boston speed 56 broadcast 16175553333
 dialer map ip 20.1.1.1 name Boston speed 56 broadcast 16175554444
 dialer hold-queue 10
 dialer load-threshold 200 either
 dialer-group 1
 snapshot server 15
 no fair-queue <*>
 no cdp enable <*>
 ppp authentication chap
 ppp multilink
!
router rip
 version 2
 network 10.0.0.0
 no auto-summary
!
ip classless
ip http server
!
dialer-list 1 protocol ip permit
dialer-list 1 protocol ipx permit
!
line con 0
 password console
 login
line aux 0 <*>
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
isdn switch-type basic-5ess
!
interface Ethernet0
 ip address 20.1.1.1 255.0.0.0
 ipx network 200
!
interface BRI0
 no ip address <*>
 encapsulation ppp
 dialer rotary-group 0
 isdn spid1 0155533330 5553333
 isdn spid2 0155533330 5554444
 no fair-queue <*>
 no cdp enable <*>
!
interface Dialer0
 ip unnumbered Ethernet0
 encapsulation ppp
 ipx network AAAA
 no ipx route-cache
 ipx watchdog-spoof
 dialer in-band
 dialer idle-timeout 300
 dialer map snapshot 1 name Atlanta speed 56 14045551111
 dialer map ipx AAAA.0000.0caa.1111 name Atlanta speed 56 broadcast 14045551111
 dialer map ipx AAAA.0000.0caa.1111 name Atlanta speed 56 broadcast 14045552222
 dialer map ip 10.1.1.1 name Atlanta speed 56 broadcast 14045551111
 dialer map ip 10.1.1.1 name Atlanta speed 56 broadcast 14045552222
 dialer hold-queue 10
 dialer load-threshold 200 either
 dialer-group 1
 snapshot client 15 600 suppress-statechange-update dialer
 no fair-queue <*>
 no cdp enable <*>
 ppp authentication chap
 ppp multilink
!
router rip
 version 2
 network 20.0.0.0
 no auto-summary
!
ip classless
ip http server
!
dialer-list 1 protocol ip permit
dialer-list 1 protocol ipx permit
!
line con 0
 password console
 login
line aux 0 <*>
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 ISDN Troubleshooting Assistance Faxback Doc #isdn_ts

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