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New Member

ISDN dial backup - Layer 1

Hello,

I have a router Cisco 1721 with IP software version 12.3, in ISDN dial backup configuration.

The output for show isdn status is :

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

Router_1721#sh isdn status

Global ISDN Switchtype = basic-net3

ISDN BRI0 interface

dsl 0, interface ISDN Switchtype = basic-net3

Layer 1 Status:

DEACTIVATED

Layer 2 Status:

Layer 2 NOT Activated

Layer 3 Status:

0 Active Layer 3 Call(s)

Active dsl 0 CCBs = 0

The Free Channel Mask: 0x80000003

Total Allocated ISDN CCBs = 0

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

I would like to ask if it’s normal for Layer 1 to become ACTIVATED only when traffic will pass through ISDN interface.

BR,

Sorin

1 REPLY
New Member

Re: ISDN dial backup - Layer 1

Yes, Sorin, that is normal for basic-net3 switch-type BRIs. Some European ISDN always in the past charged for Layer 2 connectivity so BRIs using basic-net3 were kept down (Layer 1 DEACTIVATED) until needed. "debug dialer packet" will tell you when an interesting packet has reached your dialing interface. Then you should see Layer 1 go up and Layer 2 negotiation will occur. If you also turn on "debug isdn q921" you will see the Layer 2 negotiation, and you'll see the ISDN call messages more easily if you turn on "debug isdn q931". None of the debugs are needed of course, but you can see the messages if you want to.

Scott

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