Question and Answer

Keven Cahoon, vice president, Enterprise Services, GlobeCast

March 09, 2004
Why should network managers consider satellite vs. terrestrial Webcasting for training networks?

Network managers responsible for building wide-area video-based training networks typically think of Webcasting as a solution. For companies needing to deliver full-motion video to more than a dozen sites, satellite is the best way to go. Compared to terrestrial Webcast-based training networks, enterprise satellite solutions offer advantages such as:

Reliability: A terrestrial solution has unique routes to each training site with many unknown points of failure and separate networks on each route. Network availability is much higher and easier to track on satellite. Satellite overcomes terrestrial failure points offering superior end-end network reliability and easier management.

Quality of Service: Satellite solutions can guarantee quality-of-service with dedicated bandwidth end-to-end. Terrestrial Webcast solutions, particularly if over the public Internet, only provide best-effort delivery of packets at each routing point on each route.

Video quality: Satellite provides consistent, dedicated bandwidth up to 9 Mbs at an economical price. Terrestrial solutions are limited from 128 Kbs to 1.5 Mbps depending on the type of connection available at a particular home or field office and the amount of traffic on the connection.It is not economical to terrestrially deliver 3 Mbs video to geographically dispersed sites. If the end user’s career depends on successful training, then Webcasting’s jerky, grainy video, audio-drop-outs and frame-locks are not acceptable. If you were the person requiring training to keep your job certification and paycheck, would you want to rely on poor video and intermittent audio of a Webcast?

WAN performance: Delivering video on a separate satellite network will not flood your WAN. Adding video to your terrestrial WAN takes a huge amount of capacity away from critical data/voice services. In fact, satellite integrations can supplement and improve WAN performance.

Network architecture: A satellite solution provides a single box, fully integrated solution for remote site network connectivity, video decoding, video recording, content management, video playback, encryption and network management. In contrast, terrestrial solutions typically require a box for network connectivity, a LAN server with specialized content management and redistribution software and a dedicated client PC performing software decode of the video and video graphics array to composite video conversion. Unlike the satellite solution, additional software may be needed for encryption and limited network management.

Latency: The satellite provides a uniform, acceptable latency. Terrestrial latency can vary greatly, depending on each individual end user path. We’ve seen cases of buffering on terrestrial based software decoders as high as 20 seconds in order to overcome network inconsistencies.

Scalability: The satellite solution is scalable to handle growth to multiple simultaneous high quality video streams, and virtually unlimited additional broadcast receive sites. In addition, it’s scalable from desktop video distribution to HDTV quality. The terrestrial solution can only handle a single stream of high quality desktop video or a marginal quality conference room television stream.Unlike with satellite, the more sites, the more terrestrial bandwidth you need to buy. For more information, visit GlobeCast at www.globecast.com.

Keven Cahoon is vice president of Enterprise Services for GlobeCast in the United States..