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Desktop Video |
September 14, 1998
Contact: Pamela Perdue
Executive Summary
Desktop video is clearly in the educational and computer industry's short-term future. Software and electronics required for the desktop are evolving fast and the pricing is dropping rapidly. During summer 1998, network vendors began releasing network software intended to manage the video streams. This software is version 1.0 and will evolve over the next year or two to insure consistent delivery of the video steams. Rapid expansion of the low cost desktop video without concurrent network improvements will create a network overload condition if these two worlds are not coordinated well.
VCCS guidelines and college implementations of campus networks are satisfactory for current intermittent data handling. However, continuous video streams to every desktop will increase the load on the campus network electronics. The fiber and copper cabling will support the additional demands, but the VCCS must upgrade its network electronics guidelines and prepare for a second round of investment in network software. This round of investments will be software driven which means that software provides the features and techniques as opposed to the hardware. Hardware may have to be upgraded to support the software.
The Technology Infrastructure Steering Committee has initiated a study to develop the guidelines for this electronics upgrade. Each college will need to review its college technology plans to insure college networks are ready to handle the potential demand of desktop video. This awareness and planning will provide an organized transition into this new world. Video streams are part of the Internet 2 strategy; Net.Work.Virginia has been in the forefront of Wide Area Networks; the industry direction is clear, and potential instruction and administrative uses of desktop video is a natural for integration into the VCCS's application world. We must prepare carefully to avoid problems that could impact the VCCS.
Desktop Video
Many college staff members are eager to begin using desktop video. Prices have dropped and more vendors are integrating their video and audio support with Microsoft's Net Meeting for sharing documents in a white board approach. At this time, entry level quarter screen equipment lists at $200 and up. Full screen technology is still in the $2,000 list price range. It all appears deceptively simple to plug in the desktop equipment and begin talking with another person at some distance away. In fact, it is easy once certain "rules of the road" are learned, video bridges are installed, and the network electronics are in place.
Each desktop takes a separate network stream that it uses on a continuous basis (like using a TV). Typical data access via the network is a start and stop burst of information so a network path can be shared (similar to using the telephone). In essence, twenty five desktops in a classroom are twenty five separate paths and not a single shared path. The following table shows the calculated number of concurrent sessions supported by the typical network bandwidths installed in the colleges.
| Desktop Video (H323) - Calculated Number of Concurrent Sessions | ||||||||
|
Working |
Quarter Screen |
Full
Screen | ||||||
|
bps |
384,000 |
768,000 |
1,500,000 |
3,000,000 |
4,500,000 |
6,000,000 | ||
| Desktop | ||||||||
| 10 shared |
6,000,000 |
16 |
8 |
4 |
2 |
1 |
1 | |
| 16 shared |
12,000,000 |
31 |
16 |
8 |
4 |
3 |
2 | |
| 10 switched |
8,000,000 |
1 |
1 |
1 |
1 |
1 |
1 | |
| 25 ATM Switched |
21,250,000 |
1 |
1 |
1 |
1 |
1 |
1 | |
| Backbone | ||||||||
| 10 shared |
4,000,000 |
10 |
5 |
3 |
1 |
1 |
1 | |
| 10 switched |
8,000,000 |
21 |
10 |
5 |
3 |
2 |
1 | |
| 16 shared |
12,000,000 |
31 |
16 |
8 |
4 |
3 |
2 | |
| 25 ATM switched |
21,250,000 |
55 |
28 |
14 |
7 |
5 |
4 | |
| 45 DS3 ATM - Sonet |
38,250,000 |
100 |
50 |
26 |
13 |
9 |
6 | |
| 100 Ethernet |
60,000,000 |
156 |
78 |
40 |
20 |
13 |
10 | |
| 155 ATM - Sonet |
131,750,000 |
343 |
172 |
88 |
44 |
29 |
22 | |
| 622 ATM - Sonet |
528,700,000 |
1,377 |
688 |
352 |
176 |
117 |
88 | |
As one can see, a classroom of
twenty five quarter screen desktops requires at least ATM or 100 Ethernet in the
backbone to handle the bandwidth demand created by quarter screen video. Full
screen video requires ATM in the backbone. This assumes that all video stays on
campus. Once it begins to leave the campus, the bandwidth in the
Net.Work.Virginia link would have to be expanded for full screen sessions but
could handle a given number of quarter screen sessions as shown in the 45 DS3
row above.
Perspective for Desktop Video
The new versions of desktop video are available at a reasonable price for quarter screen products and can be considered emerging technology ready for organizing into an instructional, administrative, or other process. Full screen video will evolve for a while longer as TV quality full screen takes a lot of bandwidth or improved compression techniques. Today's full screen technology will be replaced as the products evolve and mature. Pricing will also come down at that time. No matter how good and value priced the desktop software and hardware becomes, it is the network that requires considerable investment of time, energy, and dollars.
Net.Work.Virginia and the campus networks must be checked and validated for the ability to handle video and voice "time dependent" packets. Data packets and circuit emulation (Vtel video) have been validated throughout the network. The new technologies for video and voice transmissions are continuous steams of information transmitted in IP (Internet Protocol) packets. This implies new features and management requirements. It requires a new round of investment in the supporting network technologies that are just now emerging from the vendor's product development facilities. In essence, this is what "Internet 2" consortium of research universities is all about.
Campus networks were installed based upon data network specifications. The category 5 copper wire and the fiber optic cables are capable of handling the higher bandwidths required for desktop video. However, the electronics purchased did not include today's desktop video specifications because they did not exist at that time. The vendors are beginning (summer 1998) to release the specifications and software to install in the electronics. Therefore, we have a new wave of technology coming at the colleges.
This is a time when the colleges will be able to test their electronics vendor's capability to keep pace with the marketplace. Electronics in this case includes network interface cards inserted in PCs, hubs, switches, routers, etc. Network interface cards will need additional memory for buffering to handle the video stream. Hubs, switches, and routers will need higher bandwidth ports.
Initially, a separate set of routers will be required to cleanly manage the video and voice requirements. Normal data packets are batch oriented and not "time dependent". It does not matter if the packets get delayed as they pass through the network. A large file transfer can interfere with many other packets for a few seconds and everything is okay. In a video and voice world, the packets are real time or very "time dependent". A delay in transmission impacts the video quality or the voice quality. It could destroy a video conference or video presentation. Therefore, it is a good idea to build two logical IP networks over the one physical ATM network. Using multiple routers and IP logical networks prevents packet backup when a large data file or video transmission places demands on the network.
New Management Software
Routers will require new video steaming software for proper handling of video and voice. This software manages the quality of service for sessions currently on the network. It also controls how many sessions that can be established based upon the bandwidth available. If the bandwidth is totally committed, then the software issues a "busy signal message" and asks the individual to try again later. Without this type of network management, too many sessions would be created and the performance for each of them would deteriorate until it became a worthless tool. This software also manages the connectivity for broadcast video. Instead of delivering it to every desktop (as in cable TV), the individual can provide a connection request and it delivers only to the requestor (like a conference phone call).
With this software, audiovisual departments will not have to bring a VCR, TV, or other equipment to a classroom. This software delivers satellite or cable TV, VCR, CD-ROM, videodisk, video server, and Oracle repository video to any desktop connected to a campus network or Net.Work.Virginia. It supports continuous video streaming (one way video and audio). It also supports two way video, audio, and data circuits. Depending on the type of desktop software used, it may include limited multiple locations conferencing and shared white board document changes.
Quality and extended multi-point connections will still require a multi-point control unit (video bridge) to provide the connectivity. Connectivity at different bandwidths would also require a multi-point control unit with speed matching buffers. Depending on how the college intends to use the desktop video, one or more multi-point control units may be required for each campus. If a faculty member has twenty five desktops each with their own video stream connected together, a video bridge will be required to connect the more than twenty five desktop video steams. However, if another faculty member uses a classroom computer with video and projects it on the wall or large screen for all to see, then only one video stream is used in that instance (similar to the Vtel approach). It is connected to a distant location in a point to point switched circuit and a video bridge is not required. In the above cases, the connections are all switched circuits.
Preparing for a Video Future
Several steps are required to accommodate a desktop video future. The path is not totally clear of hurdles and problems. It will take several years of evolving technology until a common denominator will be accepted by the industry. For the VCCS to adopt this emerging technology means that the following actions will be required:
1. Validate the ATM Switched Virtual Circuit (SVC) paths in Net.Work.Virginia. Execute pilots working together with the Net.Work.Virginia vendors and the other customers of the network to insure that switched virtual circuits work cleanly and properly throughout the network.
2. Validate and update electronics on the campuses. Install new network interface cards with additional buffer memory, adapter boards with higher speed ports on electronic equipment, new "time dependent" routers and software, and change to switched backbone paths instead of shared paths. Pilot test the upgrades to insure proper handling of the video and voice packets.
3. Budget planning for network upgrades to support the demand. Establish guidelines for a managed expansion of desktop video on campus.
4. Evaluate need for increased bandwidth for a campus access to Net.Work.Virginia.
Planning Guidelines
The colleges have just completed the installation of desktop microcomputers, networks, and servers during the last biennium. The advent of desktop video will cause that technology to be revisited and upgraded depending on the previous decisions and actions taken. This will not happen overnight but some planning will be required. "Crystal ball" technology is never accurate, but one needs some planning measures. Please use the following guidelines until better ones are available.
1. Vtel H320 type video upgraded to switched capabilities will continue to be viable for distance learning sessions over the next three years. Those colleges with Robotel equipment are included in this category as it uses H320 technology. After three years, the H323 full screen technology should overtake the H320 technology.
2. The desktop H323 quarter screen switched video will be the medium of choice for "one-on-one" sessions. It will not replace the H320 classroom because of the screen size and quality when projected. This will be the predominate version of desktop video for several years.
3. The desktop H323 full screen switched video will be the medium of choice for classroom and group conferences. This technology will need about two years for the maturation of industry standards. We can deploy versions of these products now, but there is no guarantee of interchangeability due to varying compression techniques.
4. Network software maturation will take about two to three years for the techniques and services to be fully implemented. The first release occurred summer of 1998. Net.Work.Virginia will be ahead of the industry acceptance due to its inherent bandwidth and capability. Nationally, the "Internet 2" project will set the standards by deploying the equipment and software from participating vendors. The VCCS is working with Cisco as a partner. Cisco is a dominant "Internet 2" participating vendor.
5. Net.Work.Virginia with video can provide the foundation for various content application development efforts. The techniques can be validated between the college campuses and then extended to the home market. When the xDSL, cable modem, or other technology finally reaches the home market, the VCCS will be in a position to include it for instructional and administrative activity. This approach will bypass the current slow speed phone line technology, which absorbs a large amount of individual effort and funds.
6. Developing content and techniques for using the base desktop video technology will take many years. Instructional techniques will have to be adjusted to include several forms of remote access technology as appropriate. Administrative tasks will change because of access from remote locations.
Conclusion
The world of Information Technology is still evolving. Each shift and change offers new opportunities for those who are willing to step forward and invest in them. Desktop video certainly offers an exciting opportunity. It is one where the VCCS and Net.Work. Virginia can provide leadership by early adoption of the vendor's technology. Desktop video is a goal for Internet 2 and the educational industry. However, the desktop and network activities must be planned carefully or the opportunity will disappear because the network capabilities will not be in place to support the demand of applications integrating desktop video.
