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Cisco ASA 5500 Series Configuration Guide using ASDM
Chapter 48 Configuring Inspection for Voice and Video Protocols
MGCP Inspection
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. Figure 48-1 illustrates how NAT can be used with MGCP.
Figure 48-1 Using NAT with MGCP
MGCP endpoints are physical or virtual sources and destinations for data. Media gateways contain
endpoints on which the call agent can create, modify and delete connections to establish and control
media sessions with other multimedia endpoints. Also, the call agent can instruct the endpoints to detect
certain events and generate signals. The endpoints automatically communicate changes in service state
to the call agent.
MGCP transactions are composed of a command and a mandatory response. There are eight types of
commands:
• CreateConnection
• ModifyConnection
• DeleteConnection
• NotificationRequest
• Notify
• AuditEndpoint
• AuditConnection
• RestartInProgress
119936
Cisco
CallManager
Gateway is told
to send its media
to 209.165.200.231
(public address
of the IP Phone)
M
IP
M
M
Cisco
PGW 2200
H.323
To PSTN
209.165.201.10
209.165.201.11
209.165.201.1
IP IP
Branch offices
RTP to 209.165.201.1
from 209.165.200.231
RTP to 10.0.0.76
from 209.165.200.231
10.0.0.76
209.165.200.231
MGCP
SCCP
GW
GW
209.165.200.231