Fractionally MGCP

Answered Question
Jul 31st, 2008
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Is this workable, I know it is not offically supported but I`m sure on another site I worked on, this was configured and working- We do not wish to use H323 just yet -thanks

Correct Answer by pcameron about 8 years 11 months ago

Yes - you have to configure the Gateway with the fractional config , and turn off the config server feature to prevent the ccm from overwriting this config the next time it re-registers. The config on the router will not affect the registration of the gateway to the call manager.


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pcameron Thu, 07/31/2008 - 05:17
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Call Manager has no awareness of fractional T1 or E1 interfaces so it always assumes the T1 interface always has 24 timeslots and an E1 has 30 timeslots.


Therefore there is no obvious way to configure a MGCP fractional PRI. The workaround, while not perfect, is to do the following -


1) Not using ccm-manager config since this will always configure a full PRI. When the gateway is reset, the call manager downloads a new config file and will over write any previous configuration. So if you have a fractional T1/E1 configured under the channelised controller, it will be changed back to a full T1 or E1 when the gateway re-registers.


2) Using b channel maintenance in Call Manager to busyout the unused channels so it doesn't try to set up a call on those channels.


Here are the steps:


Go to ....

CCM Administrator > Service > Service Parameters > Cisco Call Manager >

Advanced


Then on the Advanced page, you need to go to any one of the five "Change B-Channel Maintenance Status"


For example:


Change B-Channel Maintenance Status 1


0 -- In service

1 -- Graceful out of service

2 -- Forceful out of service


e.g. so, if you wanted to only have the first 6 channels, you would add the following :


[email protected] = 0000 0011 1111 1111 1111 1111


where SDA... is the MGCP name of the gateway and the S0/DS1-0 means the slot/port of the gateway (in other words the MGCP endpoint identifier)


Enable Status polling on the Gateway configuration page.


On your MGCP Gateway, you would remove these commands to prevent the config from being downloaded and overwriting the controller settings if it re-registers


ccm-manager config

ccm-manager config server


You also need to configure the IOS gateway to use a fractional PRI config under the T1/E1 controller.


For example


controller e1 0/0/0

pri-group timeslots 1-6, 15


or


controller t1 0/0/0

pri-group timeslots 1-6, 24


iptuser55 Thu, 07/31/2008 - 05:40
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Thanks for the quick reply, Does that mean we can config. it as 1-6,15 but not to load the CCM-MANAGER CONFIG. statement so to stop teh override of teh MGCP config? Would this 1-x,15 set up stop the Router registering at all. thanks

Correct Answer
pcameron Thu, 07/31/2008 - 05:47
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Yes - you have to configure the Gateway with the fractional config , and turn off the config server feature to prevent the ccm from overwriting this config the next time it re-registers. The config on the router will not affect the registration of the gateway to the call manager.


Ayodeji Okanlawon Thu, 07/31/2008 - 06:13
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Pcameron,


+5 point for this. This is good. Never even though of busying out the unavailable channels. I just use Fractional E1 with mgcp directly.

Tommer Catlin Thu, 06/25/2009 - 07:53
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Super great post here. I have a question for you. I will this work with your MGCP configuration in the Features, if i do this:


controller T1 0/0/0


framing esf


linecode b8zs


cablelength long 0db


pri-group timeslots 1-24 service mgcp


!


controller T1 0/0/1


framing esf


linecode b8zs


cablelength long 0db


pri-group timeslots 1-7,24 service mgcp



Then take out the CCM-Manager Config in the vg config?


Thanks much!!

Tommer Catlin Tue, 07/28/2009 - 09:48
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I got this to work with (2) PRIs. One with 1-24 and the other with 1-7. No problem


So now I have 3 PRIs and the provider wants to it configured with 1-20 1-20 and 1-20.


I went in and everytime I go to configure it, i lose my serial 0/3/0 card. Its really odd.


Register the gateway with the ccm-manager config

Once I see Serial 0/0/0 and 0/0/1 and 0/3/0, I then remove the ccm-manager config.


I shut down the voice-port 0/0/0-1 0/3/0

remove bind-l3 ccm-manager from each.

Go into each controller and configure 1-20-,24

on the third controller 0/3/0, I lose it completely. Int serial 0/3/0 just drops off the config. The controller T1 0/3/0 is there, but it will not let me configure it.

or it defaults to 1-10, 24.


and whats weird is that I never put in 1-10, 24 anywhere. So Im not sure if its defaulting to this because of DSP resources or? I have 8 DSPs available and should be enough?

Tommer Catlin Tue, 07/28/2009 - 10:58
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Figured it out. I had 8 sessions for conferencing, and not enough DSPs to configure what i needed. So for whatever reason, the IOS pulls that card completely out. In ccm-config mode, it keeps it there, but leaves the channels remaining it can use... such as 1-10. I turned off my Conferencing profile, then configured my 1-14 channels, then turned on my conference profile and it flagged me to change to 6 because of DSP resources!



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