A gatekeeper is a management tool for H.323 multimedia networks. A single gatekeeper controls interactions for each zone, which comprises the terminals, multipoint control units (MCUs), and gateways within a particular domain. Although the gatekeeper is an optional component, when it is included, it becomes the central administrative entity.
Depending on the demands of the specific network, the gatekeeper oversees authentication, authorization, telephone directory and PBX (private branch exchange) services, as well as call control and routing. Other functions may include monitoring the network for load balancing and real-time network management applications, intrusion detection and prevention, and providing interfaces to legacy systems. Gatekeepers are available as either hardware devices or software applications, and are offered as proprietary products from a number of vendors, including Cisco and Symantec, or as freeware.