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New Member

debug isdn

Please, could somebody help me with ISDN problems? The config is OK, but something wrong with ISDN or WIC. Here is attach with debug output of isdn q921.


Re: debug isdn


With ref to the debug logs attached and the debug msg explaination given in CCO it seems that the remote location is tearing off the L3 connectivity.

Do find the below mentioned workarounds for the same and also the link which can help u out..


The side sending the DISConnect message has terminated Layer 3 operation on the link. It may be UAcknowledged by the other side.

The router should then send a SABME message reestablishing the link

If the disconnect message originated from the router, reset the interface using clear interface bri number or shut/no shut on the interface.

If the DISC message originated from the ISDN switch, contact the telco. If the router does not initiate a SABME, reset the interface first.


New Member

Re: debug isdn

hi again,

I red docs (ID:5705, ID:5707) about troubleshooting ISDN and put "isdn tei-negotiation first-call" command. But when I try to make connection I'm getting error messages again. Look in the attach.

When I use Lucent P75 ISDN router it works without problem (this is very old model). So I'm confused.


Re: debug isdn


try to add the command ´ppp authentication pap´ to the physical BRI interface as well:

interface BRI0

no ip address

encapsulation ppp

dialer pool-member 1

isdn switch-type basic-net3

isdn tei-negotiation first-call

isdn point-to-point-setup

--> ppp authentication pap

It is also possible that your provider is using an older type of ISDN switch that supports only speeds of 56K. Try the following configuration:

interface Dialer0

ip address negotiated

ip nat outside

ip virtual-reassembly

encapsulation ppp

dialer pool 1

--> dialer string 1499 class SPEED_56

dialer-group 1

no cdp enable

ppp authentication pap callin

ppp pap sent-username xxxx password 0 xxxxx


map-class dialer SPEED_56

dialer isdn speed 56



New Member

Re: debug isdn

I know surely that they use 64 kbps for Bs channels.

This situation is very strange because when I call isdn line attached on router than isdn status is changed and after about 30 sec is dropped. But from inside when I try pick the line up I getting errors message.

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