Hungry for Bandwidth
Hungry for Bandwidth
By Lynn Haber
High bandwidth is a must for business quality videoconferencing, where 30 frames per second (fps) for near broadcast quality is expected by commercial and government customers alike, industry officials say.
In the business sector, most midsize and larger companies have circuits that are ISDN (128 kilobits per second), T1 (1.544 megabits per second) or even T3 (45 Mbps).
On the government side, private networks with asynchronous transfer mode backbones are common, insuring high-quality videoconferencing. In fact, the government sector leads the commercial sector by 12 to 18 months in its deployment of high-speed backbone wide-area networks (WAN), industry officials say. The ATM standard provides bandwidth of between 52 Mbps and 622 Mbps.
"We believe that 15 fps at 128 kilobits per second is minimal for business videoconferencing," says Marian Levy, vice president of marketing at Tandberg, a Montreal-based supplier of videoconferencing equipment. For groups of three or more, the preferable quality of 30 fps can be achieved at 364 Kbps, Levy notes.
Tandberg's government customers include the U.S. Postal Service, the Justice Department and the FBI, to name a few.
While the bulk of videoconferencing activity is taking place on the WAN, the technology and usage is moving rapidly to the local-area network (LAN) space, where industry standard H.323 provides LAN protocols for videoconferencing.
"The biggest issue in the LAN space is that there's no guaranteed bandwidth or quality of service," says Craig Reichenbach, vice president for the federal region for PictureTel Corp. of Andover, Mass. Industry adoption of Cisco Systems Inc.'s Resource Reservation Protocol (RSVP) technology would alleviate quality of service, or prioritization, issues over the LAN, officials say.
RSVP is a protocol developed to let applications designated as high priority reserve bandwidth on Internet protocol networks. The RSVP protocol will allow users to calibrate quality of service in unicast and multicast sessions.
While everyone's eye is on videoconferencing over IP, the technology is not yet ready for prime time, with most vendors agreeing that for business usage, traditional telephone circuits of 14.4 Kbps or 28.8 Kbps are just not acceptable.