What Is a Gatekeeper?
The gatekeeper acts as an intelligent, central point of control for a real-time,
multimedia (H.323) network. It monitors endpoints and gateways as well as
audio, video and collaborative data calls.The gatekeeper can control (based on its
configuration) what stations (endpoints) participate in the network. It can also
restrict calls based on the endpoint that places or receives the call, the time of day,
and so on. In addition, it can perform various management functions such as
address resolution, directory services, as well as call authorization and accounting.
In most Cisco networks, the gatekeeper is also known as the Multimedia
Conference Manager (MCM).This is an IOS-based gatekeeper that runs on
many router platforms.The gatekeeper can be configured on an existing router
or on a new, dedicated router. Cisco recommends the 2600, 3600, or 7200 platforms
for the MCM gatekeeper. As with any function, performance will vary
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depending on the platform. (Table 5.3 later in this chapter compares the performance
of these three product families.)
Cisco has recently introduced an extension to the MCM, called the High
Performance Gatekeeper.This product greatly enhances the scalability and redundancy
of the MCM.The final type of Cisco gatekeeper comes with the Cisco
Video over IP conferencing (IP/VC) video products and is known as an
embedded gatekeeper. (Table 5.1 later in the Gatekeeper Basics section compares
the features of the three different types of gatekeepers.)