MGCP Ascendancy Commands
MGCP packets are clashing what you acquisition in abounding added protocols. Usually captivated in
UDP anchorage 2427, the MGCP datagrams are formatted with white space, abundant like you
would apprehend to acquisition in TCP protocols. An MGCP packet is either a command or a
response.
A alarm abettor uses ascendancy letters to absolute its gateways and their operational behavior.
Gateways use the ascendancy letters in responding to requests from a alarm abettor and notifying
the alarm abettor of contest and aberrant behavior.
Figure 5-18 Calls and Connections
There are eight command verbs.
Two verbs are acclimated by a alarm abettor to concern the accompaniment of a media gateway:
■ AuditEndpoint (AUEP): This bulletin requests the cachet of an endpoint. The call
agent issues the command.
■ AuditConnection (AUCX): This bulletin requests the cachet of a connection. The
call abettor issues the command.
Three verbs are acclimated by a alarm abettor to administer an RTP affiliation on a media gateway.
(A media aperture can additionally accelerate a DLCX aback it needs to annul a affiliation for its selfmanagement.)
■ CreateConnection (CRCX): This bulletin instructs the aperture to authorize a connection
with an endpoint. The alarm abettor issues the command.
■ DLCX: This bulletin informs the almsman to annul a connection. The alarm abettor or
the aperture can affair the command. The aperture or the alarm abettor issues the command
to admonish that it no best has the assets appropriate to sustain the call.
■ ModifyConnection (MDCX): This bulletin instructs the aperture to amend its connection
parameters for a ahead accustomed connection. The alarm abettor issues the
command.
Chapter 5: Examining VoIP Gateways and Aperture Ascendancy Protocols 281
Create Affiliation (CRCX)
Delete Affiliation (DLCX)
Delete ACK
Create Affiliation (CRCX)
Modify Affiliation (MDCX)
Delete Affiliation (DLCX)
Delete ACK
V V
User Information
Exchange
One verb is acclimated by a alarm abettor to appeal notification of contest on the media gateway
and to appeal a media aperture to administer signals:
■ NotificationRequest (RQNT): This bulletin instructs the aperture to watch for
events on an endpoint and specifies the activity to booty aback they occur. The call
agent issues the command.
One verb is acclimated by a media aperture to announce to the alarm abettor that it has detected an
event for which the alarm abettor had ahead requested notification (via the RQNT command
verb):
■ Notify (NTFY): This bulletin informs the alarm abettor of an accident for which notification
was requested. The aperture issues the command.
One verb is acclimated by a media aperture to announce to the alarm abettor that it is in the process
of restarting:
■ RestartInProgress (RSIP): This bulletin notifies the alarm abettor that the aperture and
its endpoints are removed from account or are actuality placed aback in service. The gateway
issues the message.