MGCP Protocol and Gateway configuration

MGCP PROTOCOL:

·         Plain text protocol that uses the server to client relationship

·         MGCP protocol contains a central component call agent(Media Gateway controller) to remotely control various devices

·         MGCP uses UDP port 2427 for Control traffic and TCP port 2428 for backhaul.

·         Call agent ---> Gateway (UDP Port used by the call agent:2427 to talk to Gateway)

·         Gateway  --->  Call agent (UDP Port used by the Gateway:2727 to talk to Call agent)

MGCP GATEWAY CONFIGURATION:

·         MGCP allows CUCM to take control of the Gateway voice ports.

·         Dial-plan completely administered from the CUCM.

·         An endpoint can be either the source or the destination for a media stream

·         Endpoint names have two components a local identifier, and a gateway identifier. The entire name consists of the local identifier, followed by the @ symbol, and then the gateway identifier.

Example: local_identifier@gateway_identifier.domain_name
The format of a local identifier varies depending on the type of interface. The local identifier for analog ports uses the following syntax:
Endpoint type/Slot #/Subunit #/Port #
For example, an endpoint name for an FXO port might look something like this: AALN/S0/SU0/1@Router1
AALN (Analog Access Line Endpoint) means that it is either an FXS or FXO interface.
S0 is the slot number that contains the voice module.
SU0 (for Subunit 0) is the slot within the network module that holds the voice interface card (VIC) or voice/WAN interface card (VWIC). 1 is the number of the voice port on the VIC or VWIC.
Router 1 is the hostname of the gateway.

·         You can get the domain name of the router by the command sh run | begin domain.

Configuration of MGCP Gateway:
      Router1(config)#mgcp
      Router1(config)#mgcp call-agent [ip-address|hostname] [port] service-type mgcp [version 0.1 | 1.0 | rfc3435-1.0] -->specifies the primary call manager ip address
      Router1(config)#ccm-manager mgcp    --->enables the mgcp to support call manager

To download much of its MGCP configuration from CallManager
      Router1(config)#ccm-manager config server {ip-address of call manager | dns-name}

Router1(config)#ccm-manager config

·         Next, you need to bind MGCP to the voice ports. You do this by configuring a dial peer for each voice port and binding MGCP to it using the application MGCPAPP command

·         Note: the directory number is not specified in the port since its configured in call manager

 Router1(config)#dial-peer voice 100 pots

Router1(config-dial-peer)#application MGCPAPP

Router1(config-dial-peer)#port 1/0/0

Configuring MGCP Fallback:
    Router1(config)#application
    Router1(config-app)#global
    Router1(config-app-global)#service alternate Default

When using MGCP fallback, you must also configure at least one dial peer with a destination pattern so that it can route outbound calls when CallManager is not available
      Router1(config)#dial-peer voice 200 pots
       Router1(config-dial-peer)#destination-pattern 9T
       Router1(config-dial-peer)#incoming called-number .

 Configuration of PRI Backhaul:

·         PRI Backhaul is the reliable transport layer connection between the CUCM and the MGCP Gateway.

·         It is the encapsulation of the Q.931 signalling in the D channel of the ISDN TDM interface.

·         Q.921 is handled by the gateway and the Layer3 in isdn q.931 is sent to the call manager.

·         The protocol q.931 is the signalling protocol and it contains the ANI, DNIS numbers.

·         The Q.931(Q.931 contains the call setup and teardown signalling) messages are tunnelled to the Voice gateway using the port 2428.

MGCP GATEWAY ADDITION IN CALL MANAGER:
Cisco CM Administration------->Device menu----->Add Gateway----->select the cisco model--->protocol=MGCP
Domain name ==>host.domainname
host==>host name of the router
domain name ===>sh run | begin domain.

MGCP REGISTRATION PROCESS:

1) gateway opens a TCP connection to Call manager
2) Gateway sends the Restart in Progress(RSIP) message to CCM
3) CCM acknowledges it
4) CCM sends audit end point(AUEP) message to gateway
5) Gateway acknowledges it
6) CCM sends Notification Request message.

MGCP Interaction with call manager:

·         MGCP uses nine types of messages between the gateway and CallManager to control the endpoints and connections.

·         The receiver must acknowledge each message. Messages between the CallManager and the gateway are sent by default to port 2427.

MGCP Gateway verification:

·         show ccm-manager  ---- > show mgcp registration status & this gives the call amanger ip address and other important details.

·         show mgcp endpoints ---- > when MGCP Gateway is registered and the end point in question is not registered. So end point registration can be verified by this command.

·         show mgcp statistics---- > to see the messages exchanged between the gateway

·         show mgcp connections---- >to check for the active calls

·         show isdn status ---- > when MGCP is controlling the T1/E1 link.

MGCP TROUBLESHOOTING STEPS:

·         Verify network connectivity ping from both directions

·         Verify call manager service is running

·         Verify CCM/IOS for compatability.

·         Verify the Hostname and domain name match.

·         Verify CCM MGCP port configuration match

Issue: MGCP Gateway is  not registering with the call manager

·         Try the command no ccm-manager config server followed by the ccm-manager config server

·         Another method no mgcp followed by mgcp will reset the MGCP Gateway-->it will drop the existing calls-->not to be used when calls volume is high.

·         Use show voice port summary--it will display the active calls in the TDM interface.