Mgcp Inspection; Mgcp Inspection Overview - Cisco 7604 Configuration Manual

Chapter 22 Applying Application Layer Protocol Inspection

MGCP Inspection

This section describes how to enable and configure MGCP application inspection and change the default
port configuration. This section includes the following topics:
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MGCP Inspection Overview

MGCP is a master/slave protocol used to control media gateways from external call control elements
called media gateway controllers or call agents. A media gateway is typically a network element that
provides conversion between the audio signals carried on telephone circuits and data packets carried over
the Internet or over other packet networks. Using NAT and PAT with MGCP lets you support a large
number of devices on an internal network with a limited set of external (global) addresses. Examples of
media gateways are as follows.
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MGCP messages are transmitted over UDP. A response is sent back to the source (IP address and UDP
port number) of the command, but the response may not arrive from the same address as the command
was sent to. This can happen when multiple call agents are being used in a failover configuration and the
call agent that received the command has passed control to a backup call agent, which then sends the
response.
Catalyst 6500 Series Switch and Cisco 7600 Series Router Firewall Services Module Configuration Guide using ASDM
OL-20748-01
MGCP Inspection Overview, page 22-65
Configuring MGCP Call Agents and Gateways, page 22-67
Configuring and Enabling MGCP Inspection, page 22-67
Configuring MGCP Timeout Values, page 22-69
Verifying and Monitoring MGCP Inspection, page 22-69
MGCP Sample Configuration, page 22-70
Trunking gateways that interface between the telephone network and a VoIP network. Such
gateways typically manage a large number of digital circuits.
Residential gateways that provide a traditional analog (RJ11) interface to a VoIP network. Examples
of residential gateways include cable modem/cable set-top boxes, xDSL devices, broad-band
wireless devices.
Business gateways that provide a traditional digital PBX interface or an integrated soft PBX
interface to a VoIP network.
Figure 22-11 illustrates how NAT can be used with MGCP.
MGCP Inspection
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