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Tandberg Video on Frame Relay
D11624 rev.01 3
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.