Dial-In Issues

Answered Question
May 4th, 2008
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Hello all,


Currently trying to troubleshoot some dialin issues that we are having. We have a cisco router connected to various modems through an Async card.


Currently the dial-up is not working correctly, the call connects, then drops after the inital connection, never getting to our authentication server.


I haven't really dealt with these issues before, is there any debug commands that I can run to see exactly where the call is failing, and why?


Thanks for any help.


Jon

Correct Answer by Makarand Chitale about 8 years 11 months ago

We have a flapping T1 line and need to get in touch with the telco, this is not an Access server problem but a telco T1 line problem. Let me explain what is happening here:


The incoming modem call get connected on the ISDN layer (initially we the isdn status as normal) and is then gets transferred to the modem, the two modem (calling and called) reach a trainup state followed by the T1 resetting causing the modem call to drop.


See explanations marked with annotation


--------------------------------------------

*Mar 1 21:19:12: %ISDN-6-CONNECT: Interface Serial0/0:22 is now connected to XXXXXXXXXX


- connected on isdn layer on bearer channel 23 (Cisco starts from 0 thru 23, where 23 is actually the 24th channel for signaling)

---------------------------------------------

Modem 1/21 Mica: in modem state CALL_SETUP

Modem 1/21 Mica: in modem state CONNECT

Modem 1/21 Mica: in modem state LINK

Modem 1/21 Mica: in modem state TRAINUP


- modem reached trainup state - now see below the T1 controller flaps.


*Mar 1 21:19:37: %CONTROLLER-5-UPDOWN: Controller T1 0/0, changed state to down

--------------------------------------------


*Mar 1 21:19:39: %LINK-5-CHANGED: Interface Serial0/0:23, changed state to reset

21:19:39: ISDN Se0/0:23: Could not bring up interface

21:19:39: ISDN Se0/0:23: Event: received MNL_RESET_REQ

21:19:41: ISDN Se0/0:23: Could not bring up interface

21:19:41: ISDN Se0/0:23: Event: received MNL_RESET_REQ

21:19:42: ISDN Se0/0:23: Could not bring up interface

21:19:42: ISDN Se0/0:23: Event: received MNL_RESET_REQ

*Mar 1 21:19:51: %CONTROLLER-5-UPDOWN: Controller T1 0/0, changed state to up


- controller finally comes to UP state.

---------------------------------------------


*Mar 1 21:19:51: %CSM-5-PRI: add ISDN at slot 0, unit 0, channel 23 with index 0

*Mar 1 21:19:53: %LINK-3-UPDOWN: Interface Serial0/0:23, changed state to up

*Mar 1 21:19:57: %ISDN-6-LAYER2DOWN: Layer 2 for Interface Se0/0:23, TEI 0 changed to down

21:19:57: ISDN Se0/0:23: Event: received NL_REL_IND

21:20:01: ISDN Se0/0:23: Event: received NL_REL_IND

21:20:05: ISDN Se0/0:23: Event: received NL_REL_IND

21:20:09: ISDN Se0/0:23: Event: received NL_REL_IND


Thanks, Mak

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Makarand Chitale Sun, 05/04/2008 - 20:30
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Jon, can you please provide more details on the setup, that is, the type of async card, the types of modems connected to them (I am assuming these are external modems connected to an async card), the configuration on the router etc?


Is this being configured for PPP? Have you tried an exec call and see if it works?


Thanks, Mak

jkloza Mon, 05/05/2008 - 03:25
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Yes this is being configured for PPP.


Can you explain the exec call ? Not sure what this is.


I can provide more information about the modems when I actually look at them :P. Unfortuantley I cannot provide configs, I can give general information, but nothing too in depth.


Thanks,


Jon

Richard Burts Mon, 05/05/2008 - 03:40
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Jon


The request from Mak is very reasonable. We need certain levels of information to be able to provide good suggestions. If you are restricted to "nothing too in depth" then you make it impossible for us to help you.


HTH


Rick

jkloza Tue, 05/06/2008 - 08:52
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Of course :), I understand that you need information to troubleshoot, but theres only so much information that I can post.


This has been working for the past 2 years, and I haven't been involved in troubleshooting this before, it was kind of a "set it and forget it" requirement.


We actually have 2 dial in solutions, an ISDN pri, and a dial-in solution. Both quit working, so now I'm trying to troubleshoot the primary one which is the ISDN PRI.


Config snippets follow -


Controller T1 0/0

framing esf

linecode b8zs

pri-group timeslots 1-24


interface loopback0

ip address 192.168.1.1 255.255.255.0


interface fa0/0

ip address x.x.x.x 255.255.255.0

no ip redirects

no ip unreachables

no ip mroute-cache

speed auto

half-duplex


interface s0/0:23

no ip address

no ip redirects

no ip unreachables

encapsulation ppp

dialer rotary-group 0

isdn switch-type primary-ni

isdn incoming-voice modem

no fair-queue

no cdp enable


interface Group-Async1

ip unnumbered loopback0

no ip redirects

no ip unreachables

encapsulation ppp

dialer in-band

dialer idle-timeout 28800

peer default ip address pool XXXXXXX-group1

no cdp enable

ppp authentication chap pap dialin

group-range 33 56


interface dialer0

ip unnumbered loopback0

no ip redirects

no ip unreachables

encapsulation ppp

no ip mroute-cache

dialer in-band

dialer idle-timeout 28800

dialer-group 1

peer default ip address pool dialin_pool

no fair-queue

no cdp enable

ppp authentication chap pap dialin

ppp multilink


ip local pool XXXXXXX-group1 X.X.X.X - X.X.X.X

ip classless


line 33 56

login authentication async

modem InOut

transport output none

autoselect during-login

autoselect ppp


If any of this seems wrong, again let me know, I'm not the one who set it up, and its my first time troubleshooting a remote access solution, I have router / switching / voip knowledge, so I've been chosen to fix this :)


Thanks for any help!

Makarand Chitale Tue, 05/06/2008 - 17:41
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Looking at the configuration it appears to be a 3600 platform with MICA (NM-24DM) modems in slot 1. It will be interesting to see if the isdn layer is fine or not and the modem status is ok or not - show isdn status and show modem is required.


Debugs to capture for an incoming call provided the above is ok:


debug isdn q931 / debug modem / debug modem csm / debug ppp nego / debug aaa authen / debug aaa authorization


Thanks, Mak

jkloza Wed, 05/07/2008 - 00:34
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Not at my job right now, but I did a show isdn status yesterday, and it showed L1, active, L2 Multiple frame established.


This is correct right?

jkloza Wed, 05/07/2008 - 06:32
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Ok, just got in, thanks again for the help. Still having the same issue, call connects, and then drops out. Attached is the debug / show commands that were needed.


Thanks again!


Jon



Attachment: 
jkloza Fri, 05/09/2008 - 03:20
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Any help would be greatly appreciated :), still having the same issues.

Correct Answer
Makarand Chitale Fri, 05/09/2008 - 15:32
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  • Cisco Employee,

We have a flapping T1 line and need to get in touch with the telco, this is not an Access server problem but a telco T1 line problem. Let me explain what is happening here:


The incoming modem call get connected on the ISDN layer (initially we the isdn status as normal) and is then gets transferred to the modem, the two modem (calling and called) reach a trainup state followed by the T1 resetting causing the modem call to drop.


See explanations marked with annotation


--------------------------------------------

*Mar 1 21:19:12: %ISDN-6-CONNECT: Interface Serial0/0:22 is now connected to XXXXXXXXXX


- connected on isdn layer on bearer channel 23 (Cisco starts from 0 thru 23, where 23 is actually the 24th channel for signaling)

---------------------------------------------

Modem 1/21 Mica: in modem state CALL_SETUP

Modem 1/21 Mica: in modem state CONNECT

Modem 1/21 Mica: in modem state LINK

Modem 1/21 Mica: in modem state TRAINUP


- modem reached trainup state - now see below the T1 controller flaps.


*Mar 1 21:19:37: %CONTROLLER-5-UPDOWN: Controller T1 0/0, changed state to down

--------------------------------------------


*Mar 1 21:19:39: %LINK-5-CHANGED: Interface Serial0/0:23, changed state to reset

21:19:39: ISDN Se0/0:23: Could not bring up interface

21:19:39: ISDN Se0/0:23: Event: received MNL_RESET_REQ

21:19:41: ISDN Se0/0:23: Could not bring up interface

21:19:41: ISDN Se0/0:23: Event: received MNL_RESET_REQ

21:19:42: ISDN Se0/0:23: Could not bring up interface

21:19:42: ISDN Se0/0:23: Event: received MNL_RESET_REQ

*Mar 1 21:19:51: %CONTROLLER-5-UPDOWN: Controller T1 0/0, changed state to up


- controller finally comes to UP state.

---------------------------------------------


*Mar 1 21:19:51: %CSM-5-PRI: add ISDN at slot 0, unit 0, channel 23 with index 0

*Mar 1 21:19:53: %LINK-3-UPDOWN: Interface Serial0/0:23, changed state to up

*Mar 1 21:19:57: %ISDN-6-LAYER2DOWN: Layer 2 for Interface Se0/0:23, TEI 0 changed to down

21:19:57: ISDN Se0/0:23: Event: received NL_REL_IND

21:20:01: ISDN Se0/0:23: Event: received NL_REL_IND

21:20:05: ISDN Se0/0:23: Event: received NL_REL_IND

21:20:09: ISDN Se0/0:23: Event: received NL_REL_IND


Thanks, Mak

jkloza Mon, 05/12/2008 - 03:38
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Thanks so much for the help, I'm working w/ our carrier now.


Again, this was much appreciated, thanks for taking the time out.


Jon

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