Gatekeepers

1
Gatekeepers
Ted Hanss H.323 Training 11 June 2004
2
Gatekeeper Services

• Admission Control
• Call Authorization
• Address Translations
• Bandwidth Management
• Zone Management
• Call Signal Routing
• Management Functions

3
H.323 Gatekeeper

• Necessary for operations, but not mandatory in
  H.323
• Required functions
• Address translation
• Call admission/authorization
• Some bandwidth management

4
Typical Gatekeeper Components

• Gatekeeper core functionality
• Web server management
• SNMP services

5
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

6
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

7
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

8
Registrants
9
Client Authorization

• Open gatekeepers
• anyone can register
• Predefined endpoints

10
Services

• Multipoint conferences (most prominent use)
• Gateways to other services
• Defined by a dial string
• Internet2 Commons conferences use 3 digits
• EG 001189700 accesses a 384K conference
• Conferences differentiate by PINs
• Internet2 Commons uses 4 digits
• EG 0011897001234 access my 384K conference

11
Defined Services
12
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)

13
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)

14
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.