[cisco-voip] MGCP Fallback to H323 fails with frac pri andccm-manager config

[Fred Nielsen]

I think a better statement might be to say that CallManager's support for
fractional PRIs when running MGCP is not very well rounded.  
 
Used to be the only way you could really get this accomplished at all was to
use the "Change B-Channel Maintenance Status" service parameters to "busy
out" individual B-channels you didn't want to use, but this didn't scale
well when you had many fractional PRIs.
 
Now it seems you are able to configure fractional service with an MGCP
configuration on the gateway, but the CallManager configuration context does
not yet consider fractional configurations.  So if you use "ccm-manager
config" CallManager will overwrite these port's configurations exactly as
you have already seen.
 
I frankly am not a big fan of "ccm-manager config" anyhow as there are not
enough people who understand that when they are tweaking knobs in CM they
are actually changing their router configurations... and performing the
equivalent of a "write mem" on those same gateways.  I don't use it ever,
even when I'm turning a gateway up.  
 
One loses the ability to reset a PRI directly from the CallManager interface
though, that is in my opinion the single biggest drawback.
 
-- Fred Nielsen

  _____  

From: cisco-voip-bounces at puck.nether.net
[mailto:cisco-voip-bounces at puck.nether.net] On Behalf Of Jason Aarons (US)
Sent: Friday, November 03, 2006 8:13 AM
To: Kevin Thorngren; cisco-voip at puck.nether.net
Subject: Re: [cisco-voip] MGCP Fallback to H323 fails with frac pri
andccm-manager config



In production we are seeing no known issues with  "pri-group timeslots
1-10,24 service mgcp"  (minus ccm-manager config) back to CallManager.

 

Am I missing something, is something broke I am not seeing? I'm wondering if
I should go back onsite and re-work it to H.323?

 

http://www.cisco.com/en/US/tech/tk1077/technologies_tech_note09186a00806fedb
e.shtml

 

I was thinking the above document had old info and needed tech review. I
thought it was unsupported as older IOS didn't allow timeslots 1-X,X service
mgcp.  Remember when service mgcp was application mgcpapp on the voice-port?
Versus being on the controller and timeslots?

 

I've seen FXS voice ports randomly shutdown in IOS, so from a best practice
I've been removing ccm-manager config once the router is up/working.

  _____  

From: Kevin Thorngren [mailto:kthorngr at cisco.com] 
Sent: Friday, November 03, 2006 10:46 AM
To: Jason Aarons (US)
Cc: cisco-voip at puck.nether.net
Subject: Re: [cisco-voip] MGCP Fallback to H323 fails with frac pri and
ccm-manager config

 

No, this is not a bug. CallManager does not support fractional T1/E1 MGCP
ports. So with the "ccm mananger config" command, CallManager will update
the GW with the config file which includes all the channels for the T1/E1
port. 

 

Kevin 

On Nov 3, 2006, at 10:34 AM, Jason Aarons ((US)) wrote: 

 

Before resetting gateway 12.4(9)T in CallManager via CCMAdmin 

controller t1 0/0/0 

pri-group timeslots 1-10,24 service mgcp 

! 

ccm-manager config 

  

  

  

After resetting gateway in CallManager 

controller t1 0/0/0 

pri-group timeslots 1-24 service mgcp 

! 

ccm-manager config 

  

The Trombone feature in ccm-manager config would replace the 10 channels
with all 23 B Channels causing SRST to attempt to use Channel 23 which
doesn't exist, resolution was to remove "ccm-manager config" 

  

Is this a bug in CallManager? 

  

  

 

From: Jason Aarons (US) 

Sent: Tuesday, October 31, 2006 8:28 PM 

To: cisco-voip at puck.nether.net 

Subject: RE: [cisco-voip] MGCP FAllback to H323 

  

In 12.4(4)XC I had FXS ports randomly shutdown on 2811/VIC2-4FXO, fix from
TAC was to remove ccm config -jason 

  

 

From: cisco-voip-bounces at puck.nether.net
[mailto:cisco-voip-bounces at puck.nether.net] On Behalf Of Joe Pollere (US) 

Sent: Tuesday, October 31, 2006 7:09 PM 

To: Ruben Montes (EU); cisco-voip at puck.nether.net 

Subject: Re: [cisco-voip] MGCP FAllback to H323 

  

Ruben, 

  

Had similar issues in the past; If you are using the ccm config server and
ccm config commands Tac says that there is a long history of problems with
them. Once the ports are initially configured via CM (and ccm config
server); the ccm config server and ccm config command should be removed. 

  

Joe 

 


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