ISDN down but there are open channels

Wassim Aouadi · ‎08-26-2009

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

slmansfield · ‎08-26-2009

Did you shutdown the controller or the serial interface associated with the D channel?

Wassim Aouadi · ‎08-27-2009

yes I shut it down, along with the dialer interface. But still I have ISDN circuit up in "show isdn active" !

slmansfield · ‎08-27-2009

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.

http://www.cisco.com/en/US/tech/tk713/tk628/technologies_tech_note09186a00801509d7.shtml

HTH

chinkevi_2 · ‎08-27-2009

sound strange. Can you post your relevent config and output for everyone to see?

also sh isdn status before and after shut.