Gatekeepers

Gabe MoultonThe Ohio State UniversityMoulton.13@osu.edu

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