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New Member

Cisco - PBX problem - LOS detected

Hi guys,

I have two routers, a 3745 with c3745-ipvoicek9-mz.124-18.bin and a 2811 with c2800nm-spservicesk9-mz.124-3i.bin connected to a PBX Mitel.

Both my routers connect to the Pbx via on E1.

The configs are

3745:

sh run | s controll

controller E1 1/0

pri-group timeslots 1-31 service mgcp

controller E1 1/1

shutdown

sh run | s Serial

interface Serial1/0:15

no ip address

encapsulation hdlc

isdn switch-type primary-qsig

isdn timer T310 120000

isdn overlap-receiving

isdn protocol-emulate network

isdn incoming-voice voice

isdn bind-l3 ccm-manager

no cdp enable

2811

sh run | s controll

controller E1 0/0/0

pri-group timeslots 1-31 service mgcp

sh run | s Serial

interface Serial0/0/0:15

no ip address

isdn switch-type primary-qsig

isdn protocol-emulate network

isdn incoming-voice voice

isdn T310 120000

isdn bind-l3 ccm-manager

no cdp enable

The problem is that from time to time (about 20 times a month) the E1 connection is dropped and then restarted in a couple of minutes.

This is a log form the routers

006980: Aug 26 11:37:52.711: %CONTROLLER-5-UPDOWN: Controller E1 0/0/0, changed state to down (LOS detected)

006981: Aug 26 11:37:52.739: %ISDN-6-LAYER2DOWN: Layer 2 for Interface Se0/0/0:15, TEI 0 changed to down

006982: Aug 26 11:37:54.712: %LINK-3-UPDOWN: Interface Serial0/0/0:15, changed state to down

006983: Aug 26 11:38:38.712: %CONTROLLER-5-UPDOWN: Controller E1 0/0/0, changed state to up

006984: Aug 26 11:38:40.712: %LINK-3-UPDOWN: Interface Serial0/0/0:15, changed state to up

006985: Aug 26 11:39:29.305: %ISDN-6-LAYER2UP: Layer 2 for Interface Se0/0/0:15, TEI 0 changed to up

I can see the reason is LOS detected but i don't really know what that is.

Can anyone help me please?

Thank you,

Good day.

3 REPLIES
Hall of Fame Super Gold

Re: Cisco - PBX problem - LOS detected

you should use "clock source internal" for this connection.

Also check you're using proper 120 Ohm cable with the right pairing.

New Member

Re: Cisco - PBX problem - LOS detected

Indeed my conf on CUCM 7 is clock source external. My question is why do you think changing the clock source will solve the problem?

Thank you very much for your help.

Hall of Fame Super Gold

Re: Cisco - PBX problem - LOS detected

Clock source must be internal, because from your configuraation appears that PBX is left as "user side".

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