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Gatekeepers
Gabe MoultonThe Ohio State [email protected]
Seventh Annual Digital Video Conference March 31, 2005Atlanta, Georgia
Gatekeepers Provide:
Admission Control
Call Authorization
Address Translations
Bandwidth Management
Zone Management
Call Signal Routing
Management Functions
H.323 Gatekeeper
Necessary for operations, but not mandatory in H.323
Required Functions• Address translation• Call admission/authorization
Some bandwidth management
Typical Gatekeeper Components
Gatekeeper Core Functionality
Web Server Management
SNMP Services
H.323 Zone
Definition• A single gatekeeper and all of the end points (clients, MCUs, and gateways) that register with the gatekeeper.
Typically is a community• E.g., University or organization
Basic Operation
Endpoints register with gatekeeper
Endpoint asks gatekeeper for permission to place call to another endpoint
Endpoint signals call with other endpoint
Endpoints exchange media directly
Endpoints disconnect, notify gatekeeper
Gatekeeper Functionality
Services: • Gives access to multipoint conferences and
gateways Neighbor Gatekeepers:
• Provides inter-zone communication Network Topology:
• Allow administrator to employ traffic shaping Endpoints:
• Live list of registered users Call Control:
• Live list of active calls
Registrants
Client Authorization
Open Gatekeepers• anyone can register
Predefined Endpoints
LDAP Authenticated Endpoints
Services
Multipoint Conferences (most prominent use)
Gateways to other services
Defined by a dial string• Commons conferences use 3 digits
–EG 001189700 accesses a 384K conference
Conferences differentiate by pins• Commons uses 4 digits
–EG 0011897001234 access my 384K conference
Defined Services
Gatekeeper Alternatives
Standalone Gatekeeper• (e.g., Radvision ECS)
System Blade• (e.g., Radvision ECS on a blade of a ViaIP)
Embedded in an Endpoint• (e.g., A gatekeeper embedded in a Radvision OnLAN MCU or gateway)
Backup Gatekeeper• (e.g., Radvision Alternate Gatekeeper)
Gatekeeper Alternatives
Other Gatekeepers:• Polycom PathNavigator• Cisco (Radvision code running on Cisco IOS)• VCON Media Exchange Manager, MXM• GNU Gatekeeper (Based on open H.323)
Specific Example
Radvision embedded gatekeeper• Runs in a Radvision MCU or gateway.• PC configuration software. Provides parameter
setting, remote monitoring and user definition and control.
• Built-in telnet server. Provides optional monitoring and remote control.
• 100 simultaneous registrants and 30 simultaneous calls.
• Free !
Questions?
Gabe Moulton
Technology Engineer
The Ohio State University
614 292 8443