ISDN ISP Dial Access from C876

Unanswered Question
Apr 17th, 2009
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I have a Cisco 876W router and would like some assistance to enable the router to connect to ISP using the ISDN interface as the WAN link. The IOS has been upgraded to c870-advipservicesk9-mz.124-15.T7.bin. I have attached the running-config file The link led light on the router front panel is lit and the cd light is also blinking. The BRI0 & Dialer0 config were obtained from firewall.cx website. Please know that I am relatively new to cisco routers. I have tried different ISDN cables between telco ISDN unit and the router (all to no avail). Is a chat script required to initialize the ISDN dial up system in a way analagous to modem chat script initialization? SDM Config helped set up basic router configuration. Do I need to contact ISP for advice from their side?




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Giuseppe Larosa Fri, 04/17/2009 - 07:04
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Hello Philip,

you need to contact ISP people for sure to know what account to use and what authentication protocol, and how they present to you


Under int dialer config you need:


ppp authentication pap chap



in global config you need


username isp-remote-name password shared-pwd


or other variations like:

ppp authentication pap chap callin



you can troubleshoot using


terminal monitor


debug ppp negotiation

debug ppp authentication


if you like you can attach in a text file the output of the show commands


But the first step is to contact your ISP.


to check isdn use


sh isdn status


it should show


L1: activated

L2 multiple-frame-established


Hope to help

Giuseppe


oconnor.philip Fri, 04/17/2009 - 08:49
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Many thanks Giuseppe for bothering to reply:

I don't know if the following is any help. I haven't got any output from the debug settings.

The output of show isdn status is as follows:


Global ISDN Switchtype = basic-net3

ISDN BRI0 interface

dsl 0, interface ISDN Switchtype = basic-net3

Layer 1 Status:

ACTIVE

Layer 2 Status:

TEI = 78, Ces = 1, SAPI = 0, State = MULTIPLE_FRAME_ESTABLISHED

Layer 3 Status:

0 Active Layer 3 Call(s)

Active dsl 0 CCBs = 0

The Free Channel Mask: 0x80000003

Total Allocated ISDN CCBs = 0


I have the correct ISP login details entered into the running-config file. I can authenticate to ISP under Linux with an ISDN T/A using /etc/ppp/pap or chap-secrets. I masked out ISP Login details in the config file posted earlier.


Giuseppe Larosa Fri, 04/17/2009 - 09:05
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Hello Philip,


the best way is to do


int bri0


shut


then you do

terminal monitor

debug ppp neg

debug ppp auth


int bri0

no shut


this triggers a new negotiation


ISDN status is fine


to use authentication you need

the

ppp authentication pap chap


command under dialer interface


Hope to help

Giuseppe


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