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Multiflex Card: Drop & Insert problem.

I have installed a multiflex card (VWIC-2MFT-E1-DI) on a Cisco 2600 running ISO 12.2(12a). I have configure the Drop & Insert as such:

controller E1 1/0

clock source line primary

pri-group timeslots 16-31

tdm-group 1 timeslots 1-15


controller E1 1/1

pri-group timeslots 16-31

tdm-group 1 timeslots 1-15

connect tdm1 E1 1/0 1 E1 1/1 1

Where E1 1/0 connects to the PSTN and E1 1/1 to a Nortel PBX.

Everything works fine, except that incomming calls are failing 50 % of the time.

What I noticed that the E1 1/0 controller is using the PRI channels sequentially starting from channel 1 (which it shouldn't, as I understand D&I). So from channel 1-15 the calls are failing, then they succeed for 15 times and fail again.

I am receiving the following message on the console:

%ISDN-6-CHAN_UNAVAILABLE: Interface Se1/0:15 Requested Channel 1 is not available.

Does anyone have a clue of what is going on? Is it a bug or a some misconfiguration? I really appreciate any help.


New Member

Re: Multiflex Card: Drop & Insert problem.

Do you have enough DSP's?? If this is the case you will usually see an error at boot, but it will continue to boot.

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New Member

Re: Multiflex Card: Drop & Insert problem.

I have 60 DSPs, 30 allocated to the pri-groups on both controllers.

New Member

Re: Multiflex Card: Drop & Insert problem.

From what I can see is that you have 1 e1 pri from the phone company and you want to share the circuit between your ip gateway and your nortel pbx.

can't do it the way you have setup.

I dont know what you set up with the phone company but if you have just ordered a regular pri circuit from them the switch at the phone company thinks it is connected to only one endpoint.

so what you get is calls comming in an acending or decending order. the gateway is setup to be the pri endpoint but only has half of the avaible ds0's connfigured on it. So the switch at the phone company will start at one end of the ds0 slots and work it's way through them. hence half of the calls fail. The calls that are comming on the dso's that you have mapped through go to the nortel. The nortel and the phone company switch do not have a layer 3 isdn connection so the call gets droped.

If you were to leave you configuration as described above and get a telco tec on the phone he would see only half of the ds0's in service.

If you want to use the same circuit for both devices i would set it up this way.

on the first e1 set up all the ds0's as one pri circuit. then set up the second e1 with all the ds0 as one pri. If you have different blocks of numbers and are using the gateway as h.323 set up a dial peer with a pattern match for all the number that need to go to the nortel. I.E. destition-pattern 5XXX go to the second e1 and then dial peers for the extensions that need to stay on the voip side.

If you are running the gateway as an mgcp gateway then use a blanket routepatterens to send the nortel extension out the second e1 and the voip extension will be allready be know from callmanager.

What you have setup would work if the circuit was not a pri circuit but a cas circuit and you have the phone company send calls for number 5100-5149 on ds0 1-15 and 5150-5199 on 16-31 but in the design you lose the benifits of isdn.

hope this helps


New Member

Re: Multiflex Card: Drop & Insert problem.

thanx for your reply, it was quite informative.

I was thinking along the same lines, and now will give a try using all 31 channels without D&I

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