Information Technology Reference
In-Depth Information
MGCP
MGCP is a client/server signaling protocol that is used to allow centralized call processing
agents (such as CUCM) to control gateways in VoIP networks. MGCP is defined in RFC
3661. MGCP's primary advantage is centralized device and dial plan configuration. Figure
14-19 shows a network where MGCP is used by the CUCM to control a voice gateway.
MGCP gateways handle transition between TDM and IP voice network. MGCP is also
used to provide enhanced functionality such as QSIG trunking, which is not supported in
H.323 or SIP IOS gateways, and gateway failover and load balancing.
CUCM
MPLS
MGCP
V
Gateway
PSTN
IP Phones
RTP
Figure 14-19
MGCP
MGCP defines two components: call agents and endpoints. In MGCP networks, endpoints
cannot function without communication and control from the call agent. Call agents such
as CUCM control the gateways. An endpoint is any gateway interface, such as a PRI trunk
or analog interface.
H.323
H.323 is a standard published by the ITU that works as a framework document for multi-
media protocols, including voice, video, and data conferencing, for use over packet-
switched networks. H.323 standards describe terminal (endpoints), gateway, gatekeeper,
and multipoint control unit (MCU) devices to be used in a multimedia network.
As shown in Figure 14-20, H.323 includes the following elements:
Te r m i n a l s :
Te l e p h o n e s , v i d e o p h o n e s , a n d v o i c e - m a i l s y s t e m s (d e v i c e s t h a t p r o v i d e
real-time two-way voice).
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MCUs:
An MCU is a device used for joining together multiple audio/video streams
into a single bridge, or conference. The MCU is responsible for taking streams from
the different conference participants, mixing the streams together, and then sending
the combined stream back to the participants.
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Gateways:
A device that provides transitional services from one network type to an-
other such as connecting a VoIP network to a TDM network such as the PSTN (ana-
log/T1 PRI). Gateways also provide translation services between H.323 endpoints
and non-H.323 devices.
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