Cisco 500 Series, Configuration Manual

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25-55
Cisco Security Appliance Command Line Configuration Guide
OL-12172-03
Chapter 25 Configuring Application Layer Protocol Inspection
MGCP Inspection
Figure 25-4 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
The first four commands are sent by the call agent to the gateway. The Notify command is sent by the
gateway to the call agent. The gateway may also send a DeleteConnection. The registration of the MGCP
gateway with the call agent is achieved by the RestartInProgress command. The AuditEndpoint and the
AuditConnection commands are sent by the call agent to the gateway.
All commands are composed of a Command header, optionally followed by a session description. All
responses are composed of a Response header, optionally followed by a session description.
• The port on which the gateway receives commands from the call agent. Gateways usually listen to
UDP port 2427.
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