Cisco ASA 5512-X Configuration Guide

14-12
Cisco ASA Series Firewall CLI Configuration Guide
Chapter 14 Inspection for Voice and Video Protocols
MGCP Inspection
Monitoring H.323 RAS Sessions
The show h323 ras command displays connection information for H.323 RAS sessions established
across the ASA between a gatekeeper and its H.323 endpoint. Along with the debug h323 ras event and
show local-host commands, this command is used for troubleshooting H.323 RAS inspection engine
issues.
The following is sample output from the show h323 ras command:
hostname# show h323 ras
Total: 1
GK Caller
172.30.254.214 10.130.56.14
This output shows that there is one active registration between the gatekeeper 172.30.254.214 and its
client 10.130.56.14.
MGCP Inspection
The following sections describe MGCP application inspection.
• MGCP Inspection Overview, page 14-12
• Configure MGCP Inspection, page 14-13
• Configuring MGCP Timeout Values, page 14-16
• Verifying and Monitoring MGCP Inspection, page 14-16
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:
• Trunking gateways, that interface between the telephone network and a Voice over IP network. Such
gateways typically manage a large number of digital circuits.
• Residential gateways, that provide a traditional analog (RJ11) interface to a Voice over IP 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 Voice over IP network.
MGCP messages are transmitted over UDP. A response is sent back to the source address (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. The following figure illustrates how you can use NAT with MGCP.

Cisco ASA 5512-X Specifications

General

Brand	Cisco
Model	ASA 5512-X
Category	Firewall
Language	English