Using ISDN as backup line for 878 router

[naorelkayam]

Hi,

We started using the 878 router for our SDSL subscribers. Now, I noticed that it has an ISDN modem included (BRI0 interface).

How can I use it to act as a backup line?

I already know the commands for configure the backup interface. but what next?

how to make it dial with the user and password?

Thanks...

Naor Elkayam

[Georg Pauwen]

Hello,

from your post, it looks like you already have configured the BRI/Dialer interfaces on your router. Regarding the authentication, typically the commands 'ppp authentication pap' and 'ppp pap sent-username USERNAME password PASSWORD' are configured on the dialer interface. The username and password should have been given to you by your ISP.

If you post your configuration, I can have a look at what might be missing...

Regards,

GP

[naorelkayam]

Hi,

Thank you for helping!!

Well, I only configured it to work as DSL router.

Tommorow I will make some configurations and post them here for you.

As I understood, these are the steps:

1. Configure the BRI0 as a backup interface

2. Configure the BRI0 (Dont know how but I will look)

3. Create a dialer interface with the commands that defines the number to dial and these two commands you gave me.

Is that correct? (more or less)

[naorelkayam]

O.K, That's the sh run output:

Current configuration : 1117 bytes

!

version 12.3

no service pad

service timestamps debug datetime msec

service timestamps log datetime msec

no service password-encryption

!

hostname Router

!

boot-start-marker

boot-end-marker

!

enable secret ****

!

username **** password ****

no aaa new-model

ip subnet-zero

no ip routing

no ip cef

!

!

no ftp-server write-enable

isdn switch-type basic-net3

!

!

!

!

controller DSL 0

mode atm

line-term cpe

line-mode 2-wire line-zero

dsl-mode shdsl symmetric annex A

line-rate auto

!

!

!

!

interface BRI0

no ip address

no ip route-cache

encapsulation ppp

dialer pool-member 1

isdn switch-type basic-net3

!

interface ATM0

backup interface BRI 0

ip address x.x.x.x 255.255.255.0

no ip route-cache

no atm ilmi-keepalive

pvc 8/35

broadcast

encapsulation aal5snap

!

bridge-group 1

!

interface FastEthernet0

no ip address

no shutdown

!

interface FastEthernet1

no ip address

no shutdown

!

interface FastEthernet2

no ip address

no shutdown

!

interface FastEthernet3

no ip address

no shutdown

!

interface Vlan1

no ip address

no ip route-cache

bridge-group 1

!

interface Dialer0

ip address negotiated

encapsulation ppp

dialer pool 1

dialer string *******

dialer-group 1

ppp authentication pap

ppp pap sent-username **** password ****

!

ip default-gateway x.x.x.x

ip classless

!

no ip http server

no ip http secure-server

!

dialer-list 1 protocol ip permit

!

control-plane

!

bridge 1 protocol ieee

!

line con 0

no modem enable

transport preferred all

transport output all

line aux 0

line vty 0 4

!

scheduler max-task-time 5000

end

[attrgautam]

it looks fine.Can you paste the sh isdn status, sh isdn active and debug ppp auth logs if it isnt working?

[Georg Pauwen]

Hello,

you might want to change the 'backup interface bri0' statement to 'backup interface dialer0'. Also, make sure that you have two default routes with different administrative distances is your config:

ip route 0.0.0.0 0.0.0.0 atm0

ip route 0.0.0.0 0.0.0.0 dialer0 200

A common problem with backing up xDSL is that the main interface often does not go down when you loose connectivity. A workaround would be to create a tunnel and then to configure tunnel keepalives, as described in the document below:

Generic Routing Encapsulation (GRE) Tunnel Keepalive

http://www.cisco.com/en/US/products/sw/iosswrel/ps1839/products_feature_guide09186a0080087cec.html

Regards,

GP

[supreme.nkosi]

here is a good example of a config set up on one of my routers - I am sure irt will help, I twicked it so Ican dial thru a NAS:

isdn switch-type basic-net3

!

!

!

interface BRI0

ip unnumbered FastEthernet0

encapsulation ppp

dialer pool-member 1

isdn switch-type basic-net3

no cdp enable

!

interface Dialer0

ip address negotiated

encapsulation ppp

no ip split-horizon

dialer pool 1

dialer remote-name ******

dialer idle-timeout 100

dialer string **********

dialer-group 1

no cdp enable

ppp chap hostname

ppp chap password *******

!

!

ip classless

ip route 0.0.0.0 0.0.0.0 Serial0

ip route 0.0.0.0 0.0.0.0 Dialer0 100

!

access-list 1 permit any

dialer-list 1 protocol ip list 100

!

end