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by Member 31688719

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I have an ISDN link from place A to place B. The configuration is such that router at place A dials or calls router at place B.When ever the link is normal, at the command "Show ISDN status" in the router at place A, I get "layer 1 active".
Now when place A routers link is up does this layer (Place A) remain active even when the called router's (place B) isdn line is down?

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by techkid

Well, Layer 1 is the physical layer so I think it's telling you that the ISDN cable is present. So yes, it could say that.

by joseph moore

The ISDN Layer 1 message you are seeing referrs to the physical connection between your BRI interface on your router and to the telco infrastructure. It really doesn't have much to do with the remote ISDN connection ("Place B").
Now, as long as youhave your ISDN BRI port(s) set up with the NO SHUT command, and providing your physical cabling from the BRI port to the telco equipment is good, then you should always have:

Layer 1 Status:
ACTIVE

If you shut down your BRI interface, then you will get:

Layer 1 Status:
DEACTIVATED

So, in normal operations, Layer 1 is Active.

For more info, go to this Cisco page about the SHOW ISDN STATUS command:
http://www.cisco.com/warp/public/129/bri_sh_isdn_stat.html
(please remove any spaces)

hope this helps

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