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Community Member

ISDN Disconnection Problem

hi,

I am unable to connect from bri isdn location to PRI isdn loaction. call is connected only for one second and immedialtely disconnects.

I am attaching here with debug isdn q931.

Lokmanya_nagar a BRI location is initiating ISDN test call To Bhopal Location ( which is PRI location ).

Thanks

Subodh

11 REPLIES

Re: ISDN Disconnection Problem

Hello,

the debug looks like it has something to do with wrong authentication. Can you post the configs of both routers ?

Regards,

GNT

Hall of Fame Super Gold

Re: ISDN Disconnection Problem

Subodh

There are some things I would like to verify. The file you posted has two sets of debug output. Even though the dates do not match, would I be correct in assuming that they are the debugs for the router placing the call and the debug for the router receiving the same call?

While I agree with GNT that authentication errors are a likely cause and something to investigate, I am not sure what in the debug GNT thinks is pointing to authentication errors. Perhaps he can clarify this - and I might learn something new about ISDN.

If we think it might be authentication errors in addition to asking for the config of the routers it would be helpful to see the output of debug ppp authentication (and perhaps debug ppp negotiation).

HTH

Rick

Community Member

Re: ISDN Disconnection Problem

hi,

Both parts of the attached file are for the same isdn test call.

I will get configuration files.

Second on emore question, This isdn line we are using as a back up for serial link. In this case will isdn test call work and will hold till idle timer expires. I have even tried to shut down serial link and then try

the test call it didnt work. Secondly I have tried to initiate a call from both locations at least one should work ( even that will solve my problem at least for time being ). I will post configurations.

I will also post ppp and nego debug output.

I think is has shown me "PASS"

I will confirm again.

Thanks

Subodh

Bronze

Re: ISDN Disconnection Problem

Hi Subodh,

From what I can see, the two sites establish a call (albeit for only 1 second). Therefore it is unlikely to be authentication.

What we will need is a snippet of your configuration, with the passwords removed for both ends.

To answer your second question, the isdn test call should work as a backup and should stay up until the idle time expires.

Also, are there any other routers in your network with this similar configuration?

Thank you,

Michael.

Community Member

Re: ISDN Disconnection Problem

Hi Friends,

I am attaching herewith debug output and

configurations of both locations.

And debug output file.

Please suggest if you find any error ?

Any chance that this problem is due to some error in ISDN Service provider ISDN switch configuration ?

Thanx.

Subodh

Re: ISDN Disconnection Problem

Hi,

As you can see in the debug output the authentication is successful, call connects but disconnects right away. There doesn't appear to be anything in the configuration that would cause this behavior. I believe this is happening because you have configured the BRI interface to be your backup interface for s0/0.

The output shows you issued the 'isdn test call' to test the connection and the 'backup delay 5 10' command forces the ISDN connection to drop 10 seconds after the router recognizes the s0/0 is up. To test the ISDN (DDR) link, remove the 'backup interface bri' command from s0/0 and initiate a test call and it would stay up as long as there is interesting traffic across the ISDN link.

Hope that helps!

Regards,

Sundar

Community Member

Re: ISDN Disconnection Problem

Hi

I Mr. Sunder I removed the dial back delay.

But still isdn test call is not getting through. secondly I have tried isdn test call with the similar type of configuration. ISDN test call still works even if back up is configured.

Please suggest..

Thanks

Subodh

Re: ISDN Disconnection Problem

Hello Subodh,

can you verify that the numbers you are calling from actually match the numbers configured with your 'dialer caller'?

Regards,

GNT

Re: ISDN Disconnection Problem

Subodh,

Can you remove both the 'backup interface' from s0/0 and initiate a test call and let us know the outcome. If problem still persists, can you turn on 'debug dialer' and post the output to see what's making the router hang up quickly.

Regards,

Sundar

Community Member

Re: ISDN Disconnection Problem

Subodh,

By chance what does your environment look like? I'm having a very similar issue with my 2821s configured to use a modem connected to the AUX port as a backup solution. All my routers using IOS prior to 12.4(3) work. And router using 12.4(3) and later have this issue. I'm hoping this is a config issue, not a bug.

Re: ISDN Disconnection Problem

Hello,

one other thing I noticed in your configuration is that on your Lokmanyangr_0768 router, you are using two dialer interfaces, one for inbound and one for outbound, and on the outbound dialer interface, you are using PPP multilink. In order to be sure that the configuration itself doesn't cause your probelm, try this simplified configuration (which actually has the same functionality):

interface BRI1/0

description *** ISDN No.(0731-2369024) ***

no ip address

encapsulation ppp

no ip route-cache

no ip mroute-cache

dialer pool-member 1

isdn switch-type basic-net3

ppp multilink

!

interface Dialer0

description *** dial out to (0755-2413002) ***

ip address 172.29.3.16 255.255.255.0

encapsulation ppp

no keepalive

dialer pool 1

dialer enable-timeout 5

dialer redial interval 15 attempts 2

dialer string 957552413015

dialer remote-name Bhopal_Dist

dialer hold-queue 50

dialer-group 1

ppp authentication chap

ppp multilink

!

dialer-list 1 protocol ip permit

Regards,

GNT

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