Videoconferencing Standards

VIDEO CONFERENCING

H.323

H.323 is a standard that specifies the components, protocols, and procedures that provide multimedia communications services - real-time audio, video and data communications-over packet networks, including Internet protocol (IP) based networks.

The videoconference services provided will be broken down into four separate subsections:

H.323 Clients (Endpoints)
H.323 Multiple Control Units (MCU)
Gateways
Gatekeepers

Terminals (Endpoints):

Videoconference devices
- Camera
- Microphone
- Codec (Coder and Decoder)
- Display unit.
Telephones
Video phones

H.323 Multipoint Control Units (MCU's)

If two or more H.323 endpoints are participating in a conference, then there are two choices: Multicasting or MCU's

Multipoint Control Units (MCU's) are required to connect two or more devices in a videoconference. All traffic destined for the conference will pass through the MCU and will be regulated there. There are many forms of MCU; they come as dedicated hardware or software solutions.

Networking infrastructure is a major concern when it comes to hosting an MCU. For every person participating in a conference on an MCU, bandwidth is taken out of the total network where the MCU is hosted. For instance, if ten people were conferencing at one time at 384Kbps, it would require a total of 7.680Mbps. For this reason it is imperative that an MCU is located as close to a customers ISP as possible, hence HEAnet's hosting of an MCU located in HEAnet's office in IFCS, Dublin 1. Figure below shows a block diagram for the MCU which different terminals are connecting to each other via MCU.

Block Diagram of MCU

A secondary use for the H.320-to-H.323 gateway could be to provide redundancy for a LAN-based MCU service. Should a network break occur, a conference couldbe routed alternately from one MCU, across a local LAN, through an H.320 gateway over ISDN, back through a second gateway and onto the LAN local to the second MCU.

Gateways

A gateway provides transcoding service es such as address translation, network protocol translation and audio/video coding translation between dissimilar conferencing technologies. For example a user using the H323 another one using the H320 (ISDN)

The MCU contains a Multipoint Controller (MC) that manages the call signaling and may optionally have Multipoint Processors (MPs) to handle media mixing, switching, or other media processing.

Gatekeepers

A gatekeeper can be considered the brains of the H.323 network. It is the focal point for all calls within the H.323 network.

Although, they are not required, gatekeepers provide important services such as addressing, authorisation and authentication of terminals and gateways, bandwidth management, accounting, billing and charging. Gatekeepers may also provide call-routing services. In order to take full advantage of the H.323 standard, all H.323 compliant terminals should register with a gatekeeper.In order to see how you can register with HEAnet's Gatekeeper please refer to quick setup guide page.

This process allows the gatekeeper to identify them to others and control their activities within the zone to provide access to an organized integrated system of users and services. The IP address of this gatekeeper for registering is 193.1.31.194

IP address in relation to GDS

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HEAnet is very happy to be the local host for the RIPE 66 meeting which is taking place on 13 - 17 May 2013 at The Burlington Hotel, Dublin.

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