ISDN down but there are open channels

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Aug 26th, 2009
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It seemed strange. I have a Leased line as primary interface and ISDN as backup.

When primary link goes down, ISDN goes up. that's fine.

But when primary link goes up, ISDN is still up. And even if I shut down PRI interface AND dialer interfaces, router show me one open circuit in "show isdn active". I don't get it. How's that? physical interface is down and yet there's an open ISDN circuit?

my IOS version is 12.4(22)T

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slmansfield Wed, 08/26/2009 - 13:05
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Did you shutdown the controller or the serial interface associated with the D channel?

Wassim Aouadi Thu, 08/27/2009 - 09:04
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yes I shut it down, along with the dialer interface. But still I have ISDN circuit up in "show isdn active" !

slmansfield Thu, 08/27/2009 - 12:17
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The command you are using displays any active calls, as opposed to active circuits.

The middle of the attached document illustrates that layer 2 goes down when you shutdown the T1 controller.

I don't know why it would still show an active call over the PRI.


chinkevi_2 Thu, 08/27/2009 - 16:02
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sound strange. Can you post your relevent config and output for everyone to see?

also sh isdn status before and after shut.


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