ISDN - Layer 2 Drops - Any way to automatically reset ISDN

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Nov 28th, 2008
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I have an ISDN connection that on occasion loses Layer 2 connectivity. The telco cannot find anything wrong and we have replaced the ISDN BRI module.

Is it possible to configure the interface or script something that monitors the L2 status and resets the ISDN interface automatically when it fails ?

The router is a 3745 acting as a voice gateway.

Thank you in advance.

Roger Norton.

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Giuseppe Larosa Fri, 11/28/2008 - 15:24
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Hello Roger,

you could build a script with a polling logic that:

a) issue show isdn status, parses its output

b) if L2 ISDN is fine does nothing else perform a shut/ no shut cycle

the correct state is :


For example you could use EXPECT that is now included in activetcl at

or other scripting library of your choice

Hope to help



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