ISDN: DDR Static IP Routing

ISDN Dial-On-Demand Sample Configuration Static IP Routing	Cisco ConfigMaker Windows 95/NT 4.0 configuration tool

This sample configuration statically routes IP between two Cisco IOS routers using PPP with CHAP authentication over an IP unnumbered ISDN link. With static routes between the two routers, there is no need for the routers to exchange routing updates and the ISDN 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 ISDN line must be activated to exchange snapshot routing updates, the duration and frequency of the snapshot interval can be configured such that any associated ISDN costs are relatively negligible compared with the benefits of simplified network administration.

Get A DDR Configuration Using Snapshot Routing (recommended)
Faxback Doc #0511

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

Preconfiguration Checklist

ISDN Information
The following info must be gathered from the ISDN service provider

ISDN Switch Type
ISDN SPIDs (where applicable)
In North America, SPIDs are required for all ISDN switch types except for 5ESS Custom Point-to-point
ISDN Directory Numbers
The directory number is the local seven digit ISDN phone number (no area codes) of your router

Network Information
The following info must be gathered from the network administrator

PPP Client Name
A PPP client name must be assigned to both locations
PPP Authentication Type
CHAP authentication is preferred and used in this example
PPP Password
A PPP password must be assigned to both locations
IP Address Information
An IP network design must be created
Phone Numbers
ISDN phone numbers of both locations

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
isdn switch-type basic-ni1
!
interface Ethernet0
ip address 10.1.1.1 255.0.0.0
!
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
dialer in-band
dialer idle-timeout 300
dialer map ip 20.1.1.1 name Boston speed 56 16175553333
dialer map ip 20.1.1.1 name Boston speed 56 16175554444
dialer hold-queue 10
dialer load-threshold 200 either
dialer-group 1
no fair-queue <*>
no cdp enable <*>
ppp authentication chap
ppp multilink
!
ip classless
ip route 20.0.0.0 255.0.0.0 Dialer0
ip http server
!
dialer-list 1 protocol ip 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
isdn switch-type basic-5ess
!
interface Ethernet0
ip address 20.1.1.1 255.0.0.0
!
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
dialer in-band
dialer idle-timeout 300
dialer map ip 10.1.1.1 name Atlanta speed 56 14045551111
dialer map ip 10.1.1.1 name Atlanta speed 56 14045552222
dialer hold-queue 10
dialer load-threshold 200 either
dialer-group 1
no fair-queue <*>
no cdp enable <*>
ppp authentication chap
ppp multilink
!
ip classless
ip route 10.0.0.0 255.0.0.0 Dialer0
ip http server
!
dialer-list 1 protocol ip 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