Debugging ISDN Backup of Serial Link

[robert.peters]

We have an ISDN backup to a serial link that simply does not seem to kick in. The config seems to be correct. Can someone tell me how I could run debugging to get to the bottom of the problem.

I am only just studying my CCNA and have yet to get to debugging as yet. I also be grateful if you could tell me how to turn it off afterwards. Many thanks!

[Georg Pauwen · Accepted solution]

Hello,

the debug commands you can use are:

debug isdn q921

debug isdn q931

and

debug dialer events

To turn debugging off, type:

u all

Make sure that you have at least layer 1 connectivity, you can check this by typing:

show isdn status

The output should look like this:

Global ISDN Switchtype = basic-net3

ISDN BRI1/0 interface

dsl 0, interface ISDN Switchtype = basic-net3

Layer 1 Status:

ACTIVE

Layer 2 Status:

TEI = 81, Ces = 1, SAPI = 0, State = TEI_ASSIGNED

Layer 3 Status:

0 Active Layer 3 Call(s)

Active dsl 0 CCBs = 0

The Free Channel Mask: 0x80000003

Number of L2 Discards = 0, L2 Session ID = 212

Total Allocated ISDN CCBs = 0

Also, to view the output of the debugging, type:

term mon

and to turn this off, type:

term no mon

HTH,

GP

[robert.peters]

Many thanks!!

Can we do this remotely via Telnet or would you have to be connected via terminal?

[Georg Pauwen · Accepted solution]

Hello Robert,

no problem to do this via Telnet, you do not need to be connected via a Terminal.

Regards,

GP