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Software Configuration Guide for the Cisco VG200
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Chapter 1
Using the Cisco Voice Gateway 200
Voice over IP Overview
H.323 is a peer-to-peer protocol, helping to establish and manage connections
among H.323 endpoints. As with other peer-to-peer protocols, the many-to-many
relationships become difficult to configure and maintain in large networks. MGCP
was developed specifically to overcome the problem of scalability inherent in the
H.323 protocol.
Media Gateway Control Protocol
MGCP establishes a master-slave protocol which, when compared to H.323,
simplifies voice network administration and improves reliability and
performance. In particular, it makes configuration and administration of gateway
devices easy. With MGCP, gateways are defined by MGCP as slave devices in
relation to the master, referred to as a call agent, which manages connections
between endpoints and controls how gateways function.
Figure 1-3
MGCP
Because an MGCP gateway is a slave device, it derives most of the configuration
it requires from the call agent. To configure an MGCP gateway, all you need to do
is to identify the call agent on the gateway and identify the gateway to the call
agent. In addition, MGCP optionally supports multiple call agents, which can
eliminate a potential single point of failure in the voice network.
POTS phones
MGCP-managed endpoints
PSTN
MGCP Gateway
MGCP call agent
TCP/IP network
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