TANDBERG D11624 manual Introduction

Tandberg Video on Frame Relay

1. Introduction

This document is designed as an 'eye-opener' to video over frame relay and the idea is to show a solution that works. The equipment described in this document is the VFX-250S, a framer unit from Science Dynamics Corporation. Tandberg video conferencing codecs are being used over frame relay together with this equipment and according to the setup described here. The setup has been tested and found reliable and it works well. For abbreviations throughout the document a glossary is provided in the back.

The costs and savings of using frame relay network for video transmissions are taken from calculations by Science Dynamics and should be considered examples only. Tandberg disclaims any responsibility for inaccuracies or subsequent changes in the tariffs used in developing the above costs and savings.

Here's what it takes to make videoconferencing work on frame relays today:

∙Unfailing QoS (Quality of Service). The single most important factor in the delivery of acceptable videoconferencing over frame relay is protection of the video stream from frame drops.

∙Adequate bandwidth. You'll need 384 Kbps or more for room-based systems, 128 to 256 Kbps for desktop systems and up to 56 Kbps for surveillance systems. This is comparable to the requirements for circuit-switched connections such as ISDN (Integrated Services Digital Network).

∙CIR(Committed Information Rate) in the frame relay WAN(Wide Area Network). It must be 1 percent to 3 percent higher than selected bandwidth; you'll need additional transmission space to carry frame relay packet overhead without impeding delivery of the payload.

Tests have shown that even when flooding the concurrently running Ethernet with so much traffic that 98 percent of data packets were thrown away, the video stream rolled merrily along at 30 frames per second with no evidence of tiling faults or frame drops.

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