Cisco ISDN PRI Data Configuration

Below is the sample of configuration on setting up a PRI data connection as a backup line when the primary link is down.

The PRI module need to be supporting data channel instead of voice only.
(eg. HWIC-1CE1T1-PRI)

The following configurations work on Malaysia PRI network.

First, you need to activate the PRI module.

card type e1 0 1

Configure the PRI module for E1 channel with PRI groups.

controller E1 0/1/0
 pri-group timeslots 1-31

The primary link configuration

interface Serial0/0
 description Primary Link
 bandwidth 1024
 backup interface Dialer1
 ip address x.x.x.x y.y.y.y

The PRI D-channel configuration, mostly involve the encapsulation and isdn switch type.

interface Serial0/1/0:15
 description PRI Backup
 no ip address
 encapsulation ppp
 dialer pool-member 1
 isdn switch-type primary-net5
 ppp authentication chap
 ppp multilink

The Dialer interface configuration. Normally, only one site require the dialer string input as there will be only one site initiate the dialling while the other site listen.

As CHAP authentication will be used, so the device credential must be created on each router.

The following example will be Site A dialing while Site B listening.

 Site B Device

 username remote_siteA password abc

interface Dialer 1

 bandwidth 1024

 ip address a.a.a.a b.b.b.b

 encapsulation ppp

 dialer pool 1

 dialer remote-name remote_siteA

 dialer idle-timeout 600

 dialer load-threshold 1 outbound

 dialer-group 1

 ppp authentication chap

 ppp multilink

Site A Device

username remote_siteB password abc

interface Dialer 1

 bandwidth 1024

 ip address a.a.a.b b.b.b.b

 encapsulation ppp

 dialer pool 1

 dialer remote-name remote_siteB

dialer string #######

dialer persistent

 dialer idle-timeout 600

 dialer load-threshold 1 outbound

 dialer-group 1

 ppp authentication chap

 ppp multilink

The timeout/idle timer can be adjusted to prevent the line stuck.

The ip route configurations,

ip route c.c.c.c d.d.d.d Serial0/0/0

ip route c.c.c.c d.d.d.d Dialer1 200