RADVISION's viaIP multifunction platform provides similar capabilities. You can purchase a viaIP chassis with four slots for expansion cards for about $6000, then configure it with viaIP MCU, viaIP Gateway, and viaIP Video Processor Server cards to provide the functionality and capacity you need. A viaIP MCU module costs about $40,000 for a 30-port card and about $100,000 for a 100-port card; a viaIP gwP-20 Gateway card with two PRI T1/E1 network interfaces costs approximately $40,000. The RADVISION OnLAN PRI Gateway with an E1/T1 PRI network interface, which has half of the capacity of the viaIP gwP-20 Gateway card, costs about $29,000. At press time, RADVISION hadn't set a price for its viaIP Video Processor Server card, which handles rate matching and transcoding functions.
If you plan to implement desktop videoconferencing by using just NetMeeting clients with WebCams, you might want to consider Microsoft's ECS, which provides MCU functionality along with conference-scheduling and resource-management capabilities. The product can reside on the same server as Exchange 2000 or on another server in the same domain (you can continue to run your mailbox servers on Exchange Server 5.5). Microsoft says that ECS can support multiple concurrent videoconferences with as many as 60 participants in each conference, depending on the server and network configuration. However, limited screen real estate makes 10 to 15 conference participants a more workable figure. Figure 1 shows ECS's Web-based client.
ECS includes a multicast ActiveX control that downloads to XP and Win2K clients (these OSs support IP multicast), minimizing the videoconference's network bandwidth requirements. For example, if each of the six participants that Figure 1 shows is running Win2K, the videoconference will use six audio/video streams (typically 60Kbps to 128Kbps each). If all six users run earlier versions of Windows or the network doesn't support multicast, the ECS H.323 bridge converts each unicast stream to a multicast stream. The bridge would also send to each participant a unicast stream of the participant who's speaking, for a total of 18 streams. If one of the six participants uses NT or Windows 9x, the conference would use only 8 audio/video streams. Clients running NT or Win9x see only their own video and that of the speaker.
ECS also comes with an ActiveX control that adds NetMeeting's data conferencing controls to ECS's Web-based client, as Figure 1 shows. ECS's management capabilities include the ability to limit the number of simultaneous conferences and the bandwidth allocated for each conference. ECS also provides failover and load-balancing capabilities to ensure high availability.
ECS costs $3999, and Client Access Licenses (CALs) cost $67 each. If you already have Exchange 2000 CALs, you don't need new ones for ECS. Compared with the cost of third-party MCU's, ECS can be an inexpensive way to bring multipoint desktop videoconferencing to your enterprise, depending on the number of CALs you need to purchase, whether you'll need to buy server hardware to run ECS, whether you choose to use third-party H.323 clients, and the maximum number of users who might need to join a videoconference.
Unfortunately, ECS doesn't support third-party H.323- or H.320-based desktop videoconferencing endpoints, so you'll need a dedicated MCU if you'll have a heterogeneous videoconferencing environment. ECS also lacks support for the Session Initiation Protocol (SIP) suite, meaning that XP users must use NetMeeting rather than the more advanced Windows Messenger conferencing product. At press time, Microsoft wouldn't comment on its plans to add SIP support to ECS.
Where Do We Go from Here?
The installed base of room conferencing systems uses primarily the H.320 ISDN videoconferencing standard, but LAN-based room videoconferencing systems are slowly gaining favor as H.323-based desktop videoconferencing becomes more popular. This trend should accelerate as the installed base of Exchange 2000 and ECS continues to grow. Ultimately, IP-based solutions should be less expensive because you won't need to pay the monthly and per-minute ISDN service charges. If you plan to use the Internet instead of leased lines for IP-based videoconferencing systems, talk to prospective vendors about their solutions to the Quality of Service (QoS) problems inherent to the Internet.
Microsoft is promoting SIP as a replacement for the H.323 standard to accommodate wireless products (for more information about SIP, see "Conferencing, Windows XP—Style"). However, most vendors of room-based systems, gateways, and MCUs are taking a wait-and-see attitude toward the new protocol. Even if wireless-device manufacturers adopt SIP, I expect that the H.323 and SIP standards will coexist for some time, just as H.320 and H.323 do now. If you plan to purchase a room-based or desktop videoconferencing product but are considering videoconferencing with wireless devices for the future, ask prospective vendors about their SIP upgrade path.