Media Gateway Control Protocol (MGCP)is one of the most commonly used VoIP gateway signaling protocols with Cisco Unified Communications deployments. One of it chief virtues is that it requires very limited knowledge of Cisco Internetwork Operating System (IOS) and most of the configuration can be accomplished from within the Communications Manager GUI interface. Alternative Gateway signaling protocols include H323, Session Initiation Protocol (SIP) and Skinny Call Control Protocol (SCCP).
In this post I want to focus on some common issues that you may run into when deploying MGCP voip gateway. At a high level you will need to create the gateway in the Cisco Communications Manager database. I then typically recommend that you assign that newly created gateway to a Route Group. That Route Group should in turn be added to a Route-List.
When creating the gateway it is very important that you first check network connectivity. The gateway and Communications Manager server should be able to ping one another. Once you have chosen the router model the next important step is input the right information:
There are several items that need to be configured here correctly or they will not allow the gateway and Communications Manager to register. The Domain Name must match exactly that what is configured on the router. Secondly, you must verify the ports and slots. If you are not physically near the router you can use the “show Inventory” IOS command and that will give you the information you need. Each voice card has to be in the correct slot or else you will get unexpected results. Finally, select the ISDN switch type and click “Save”.
To configure a PRI port click on the PRI port that needs to be configured. You may or may not have some of these options set but do configure the PRI Protocol Type to the ISDN Switch Type.
After the Gateway is configured in Communications Manager and the PRI port is configure it is time to telnet to the router. I recommend you use a telnet client like Putty or SecureCRT:
pod4cme#Configuration Terminal
!
Card type t1 0 2
network-clock-participate wic 2
no ip domain name
!
ccm-manager config server 10.0.40.11
ccm-manager config
end
!
By adding five lines the gateway should be able to download all the rest of the configuration information from the Communications Manager Server.
Here are a few commands that you use to verify registration are:
1) Show ccm-manager
2) Show mgcp endpoint
3) Show isdn status
pod4cme#Show isdn status
Global ISDN Switchtype = primary-ni
%Q.931 is backhauled to CCM MANAGER 0×0003 on DSL 0. Layer 3 output may not apply
ISDN Serial0/2/0:23 interface
dsl 0, interface ISDN Switchtype = primary-ni
L2 Protocol = Q.921 0×0000 L3 Protocol(s) = CCM MANAGER 0×0003
Layer 1 Status:
ACTIVE
Layer 2 Status:
TEI = 0, Ces = 1, SAPI = 0, State = MULTIPLE_FRAME_ESTABLISHED
Layer 3 Status:
0 Active Layer 3 Call(s)
Active dsl 0 CCBs = 0
The Free Channel Mask: 0×807FFFFF
Number of L2 Discards = 0, L2 Session ID = 1
Total Allocated ISDN CCBs = 0
Pod4cme#
pod5cme#sh ccm-manager
MGCP Domain Name: pod4cme
Priority Status Host
============================================================
Primary Registered 10.0.40.11
First Backup None
Second Backup None
Current active Call Manager: 192.168.1.10
Backhaul/Redundant link port: 2428
Failover Interval: 30 seconds
Keepalive Interval: 15 seconds
Last keepalive sent: 01:32:11 UTC Nov 16 2008 (elapsed time: 00:00:11)
Last MGCP traffic time: 01:32:11 UTC Nov 16 2008 (elapsed time: 00:00:11)
Last failover time: None
Last switchback time: None
Switchback mode: Graceful
MGCP Fallback mode: Not Selected
Last MGCP Fallback start time: None
Last MGCP Fallback end time: None
MGCP Download Tones: Disabled
TFTP retry count to shut Ports: 2
Backhaul Link info:
Link Protocol: TCP
Remote Port Number: 2428
Remote IP Address: 192.168.1.10
Current Link State: OPEN
Statistics:
Packets recvd: 4
Recv failures: 0
Packets xmitted: 10
Xmit failures: 0
PRI Ports being backhauled:
Slot 0, VIC 2, port 0
Configuration Auto-Download Information
=======================================
No configurations downloaded
Current state: Waiting for commands
Configuration Download statistics:
Download Attempted : 2
Download Successful : 2
Download Failed : 0
TFTP Download Failed : 16
Configuration Attempted : 2
Configuration Successful : 0
Configuration Failed(Parsing): 0
Configuration Failed(config) : 2
Last config download command:
FAX mode: cisco
Configuration Error History:
voice-port 0/2/0:23
echo-cancel coverage 8
end
voice-port 0/2/0:23
echo-cancel coverage 8
end
pod5cme#
If the gateway does not register make sure to verify all of the options mentioned above. One common issue that I have seen is were the PRI is not up and that will not allow the gateway to register with Communications Manager. To verify that everything is working the “Show CCM-Manager” command and the Communications Manager Port configuration GUI pages has to say registered. If one is showing registered but the other is not, verify that the ports are in the correct slots and that the PRI has sending ISDN q931 and q921 packets.
#Terminal Monitor
#Debug isdn q921
#Debug isdn q931
#Undebug all
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