April 1998
by Claire Tristram
Video Conferencing: A Work in Progress
H.323 will be the dominant video conferencing standard but not for a few years. Here's
the full story.
Remember the "information super-highway"? Back when Al Gore
popularized the term in 1994, hopes were high, video-on-demand was just around the corner,
and the word network in any business plan was enough to get venture capitalists excited.
But four years later, that superhighway is still characterized by traffic jams, gridlock,
and toll booths at every LAN. Although some video applications are making their way onto
networks, at least one application - desktop video conferencing over IP networks -
continues to be more hype than reality.
The networking industry is currently promoting its latest
video conferencing standard, H.323, which addresses the challenge of delivering real-time
video and audio signals over IP networks. The International Telecommunications Union's
(ITU) H.323 standard extends H.320 (the standard developed for circuit-switched networks
like ISDN) to packet-switched networks such as Ethernet, Token Ring, FDDI, frame relay,
and the Internet. H.323 specifies how to compress and transmit real-time audio and video,
and defines protocols for managing audio and video streams. The standard also specifies
how to connect with noncompliant equipment.
IP has become the dominant network protocol, and H.323 is
therefore expected to eventually become the dominant video conferencing standard. But
H.323 is still a work in progress: Many of the vendors interviewed for this story were
still testing their H.323-compatible products, and none could provide actual customers who
have made H.323, video conferencing work for them in a production environment.
"There are many companies that have announced H.323
support," says Andrew Davis, research analyst for Forward Concepts, a market research
firm based in Tempe, AZ. "But to date, only a handful of vendors have shipped
products. Getting everything in place to make H.323 work is going to take at least five
years."
While H.323 is still a few years away from being viable, any
company with an IP network (and that's most of us) will benefit from being aware of the
trends.
The H.323 standard enjoys widespread industry enthusiasm;
every video conferencing vendor has either announced a forthcoming H.323-compliant desktop
offering or has recently come to market with one.
END STATIONS SOLVED (SORT OF)
The H.323 standard enjoys widespread industry enthusisiasm; every video conferencing
vendor has either announced a forthcoming H.323-compliant desktop offering or has recently
come to market with one.
Early entrants with fully integrated products include
PictureTel (Andover, MA), with its LiveLAN 3.0, (see Video conferencing for the
Enterprise, page 98, by William Wong) and Intel (Santa Clara, CA), with its Business Video
Conferencing System 3.0 Both products, which are aimed at corporate business users, are
hardware-based solutions that include a camera, compression/decompression (codec) boards,
and networking elements.
Other players likely to capitalize on their strong
experience in codec technology include Austin, TX-based VTEL, Manchester, NH-based
Zydacron, and Dallas- based VCON (a subsidiary of VCON Ltd. in Herzliya, Israel). Along
with PictureTel and Intel, these vendors will target corporate users and try to
differentiate their products in terms of picture quality, audio quality, bandwidth
efficiency, and ease of management
A few software-only solutions are also on the market,
including CU-SeeMe 3.1 from White Pine Software (Nashua, NH) and NetMeeting 2.1 from
Microsoft. Software-based desktop video conferencing products deliver lower quality than
their hardware-based counterparts, but they are priced to attract widespread adoption. For
example, NetMeeting, which comes sans camera, can be downloaded from Microsoft's Web site
for free.
Both Microsoft and White Pine are offering products they
believe will appeal to a new class of user: someone who wants the enhanced communication
that video can provide, but who doesn't necessarily need the high quality provided by H.320
room systems. Both vendors believe there is a market for low-cost, low-quality video
conferencing products - in the consumer market as well as in the low end of the business
market.
But there's still a question of whether these solutions
enhance communication or squash it.
"NetMeeting's performance is horrible," says
Forward Concepts' Davis. "I need to quit after about 30 seconds. Half the syllables
you speak are lost because the infrastructure isn't there to support it yet."
To be fair, although NetMeeting has video conferencing
capabilities, Microsoft isn't planning to market them heavily to the corporate market.
"For consumers, the key capability of NetMeeting is the
use of video," says Brent Ethington, Microsoft product manager for NetMeeting.
"Video enhances the ability to communicate with family and friends. But in the
corporate world, does the fact that we don't have video on a telephone call really detract
from our communication? I don't think so."
In the corporate world, Microsoft is instead positioning
NetMeeting as a tool for collaborative document sharing.
"Most corporations are using [the product] for data
conferencing," says Ethington. "It lets users connect in a multipoint conference
and share applications. One participant can share a spreadsheet with other participants,
so they all see the same data; meanwhile, they audio conference over the telephone."
PictureTel, Intel, VTEL, VCON, and Zydacron have all bundled
NetMeeting into their video conferencing products for use as a data conferencing tool.
Microsoft has been shipping NetMeeting 2.0 with Windows 95, and Windows 98 includes
functionality that will allow users to request and reserve bandwidth for their H.323
applications.
THE NETWORK CONNECTION
Although product comparisons of H.323-compliant desktops have appeared with increasing
regularity in various trade magazines, H.323-compliant products offer such a range of
quality, management, and connectivity features that such comparisons are not very useful.
In addition, focusing so much attention on the end station has obscured the fact that the
greatest challenges of implementing desktop video conferencing are on the network, not on
the desktop.
"Most products today are just clients sitting on
desktops," says Smita Gupta, research group manager for VTEL. "The network to
support them isn't there yet. H.323 is a very good idea, and it uses billions of dollars
of infrastructure already in place. But these networks were never designed to carry
real-time traffic. The capability to do so is being slowly developed, but it's not going
to happen overnight."
The demands of video conferencing - two-way, continuous,
simultaneous delivery of audio and video signals - make it the most difficult video
application to run over a packet-switched network. The problem isn't about bandwidth;
compression technologies have evolved to the point where even a 56Kbit/sec pipe can carry
a video conference of acceptable quality. The real roadblock to desktop video conferencing
is TCP/IP, the ubiquitous protocol that chokes on real-time video.
TCP/IP is a great way to get data from one machine to
another, with 100 percent accuracy, and over multiple network technologies. What if a few
packets hit network congestion or a hardware failure? No problem: They just get rerouted.
What if a few packets get lost along the way? Again, no problem. Any computer in the
network can say the equivalent of, "Hold it, I need that retransmitted."
But the very strengths of TCP/IP make video conferencing a
tricky proposition. For a video application, the data must arrive consecutively, or it's
useless. A fundamental trade-off must be made between reliability and timeliness. TCP/IP
also provides developers with a choice of variable packet lengths (again, great for data
transfer, disastrous for video delivery). Because each device along the network needs to
determine the length of each packet, it copies the whole packet into memory before
forwarding it. This process slows transmission and degrades video delivery considerably.
The H.323 standard replaces TCP with UDP (User Datagram
Protocol), a simple protocol originally developed to send short messages that didn't
require data integrity. Using UDP guarantees that none of the network elements will
compromise the transmission by asking for packets again. It also means that H.323 has no
way to guarantee the data integrity of video signals. Although the use of Real-Time
Protocol (RTP) over UDP provides for sequential arrival of data, H.323 contains no
provision for ensuring that data arrives at all. The only way to preserve quality is to
avoid collisions altogether, which can be done by increasing bandwidth until collisions
don't occur.
"The H.323 standard provides no guidelines for
quality," notes Gupta. "It just tells you how to send the bits. There aren't any
guidelines for what to do if chunks of information are missing."
To preserve video and audio quality within local networks -
and at the same time protect those networks from the congestion that video conferencing
applications can cause - you currently have two options: You can buy an Ethernet switch
and provide a dedicated l0Mbit/sec segment to each desktop requiring video conferencing;
or, you can regulate the amount of bandwidth dedicated to each video call by using call
management software that employs the Resource Reservation Protocol (RSVP).
Scott Darling, director of Intel's small business
communication group, has observed that early adopters of H.323 video conferencing often
designate a switched Ethernet segment to a single desktop, and make this desktop a shared
resource within a workgroup. "We've sold some products as group systems, where there
is a unique LAN segment into a conference room running at l0Mbits/sec," he says.
"That's more than enough of a data rate for a quality experience."
The question IS managers have to ask is whether buying an
Ethernet switch to designate a l0Mbit/sec segment for the desktop video conferencing
system makes more economic sense than ordering and installing an ISDN line for that system
- a technology that has been proven for about 10 years.
"Microsoft and other vendors clearly want to convince
users that their network of choice is the Internet," notes Gold, president of
TeleSpan Publishing (Altadena, CA). "Some people are already convinced that there is
no reason or future in ISDN. I don't agree. One thing ISDN has going for it is that it
works today."
Intel has made it easier for its customers to migrate from
one network solution to another by offering an integrated H.320/H.323 product to its
customers.
"The reality is that 99.5 percent of [video
conferencing] deployment today is circuit-switched," says Darling. "There are
still significant bandwidth issues to. be solved. IS managers are hesitant to put video on
the corporate network. While Intel believes very strongly that H.323 and H.320 will merge
under the umbrella of H.323, it's important to offer a solution that customers can easily
implement now."
NETWORK COMPONENT VENDORS
Bringing video conferencing capabilities to your corporate network also means taking on a
lot of the technical complexity that, if you video conference over a circuit-switched
network or dedicated line, is handled by your telecommunications carrier. As such, the
H.323 standard has several elements that define how networks running H.323 video and audio
should be managed within your network.
The H.323 Gatekeeper is a specification that lets IS
managers regulate user access and manage the bandwidth allocated to each video stream.
Intel's Darling notes that such a bandwidth allocation scheme is critical for any manager
planning to run mixed traffic over any portion of the corporate network where H.323 video
calls are taking place. "We've talked with many network administrators," he
says, "and they're concerned. They need the ability to control network usage."
H.323's Gateway specification lets H.323 devices connect to
equipment compliant with H.320 and other ITU video specifications. This capability is
critical for allowing desktop systems to communicate with a company's currently installed
base of video conferencing equipment. The H.323 gateway becomes a central point of
connectivity or disparate network types, allowing transparent connection from one
to another.
The H.323 Multipoint Control Unit (MCU) specification
describes how to link multiple H.323 users into a conference with more than two end
points.
Vendors are emerging with H.323-compliant network components
that package the gatekeeper, gateway, and MCU elements of H.323 in various ways. Although
the gateways and gatekeepers perform different functions than router or video server
elements, there is some overlap, particularly as vendors compete for where the network
intelligence will be located.
White Pine's MeetingPoint 3.0 Conference Server performs
both multipoint conferencing and gatekeeper functions, at prices ranging from $1,995 for a
10-user license to about $35,000 for loo-user license. MeetingPoint works on either a
Windows NT or Solaris platform, and allows administrators to monitor usage, allocate
bandwidth, and manage multiple simultaneous conferences from a browserlike interface.
"White Pine comes to the market with an
understanding of multipoint conferencing," says TeleSpan's Gold. "Its CU-SeeMe
product already allowed users to: see multiple sites at once. The company has taken its
original technology and made it as compatible to H.323 as possible."
Of all the hardware-based video conferencing vendors,
PictureTel has taken the most aggressive stance in its support of H.323-compliant
products, even though it is the leader in high-end, H.323-based solutions, a market that
will presumably be eroded by the advent of H.323 systems.
As early as 1994, PictureTel offered its first networked
desktop product, a proprietary software solution for both IP and Novell's IPX networks.
The company shipped its first H.323-compliant desktop systems in September 1997, and as of
January 1998 had filled over 3,000 orders.
"As we talk with IS managers, what we consistently hear
is that they want us to deliver a solution that works across their existing
infrastructure," says Rich Baker, vice president and chief technology officer for
PictureTel. "We're the only company positioned to deliver video conferencing on any
kind of network, from end to end. We're investing in providing customers with a single,
integrated solution, for which they can get the support they need in one telephone
call."
In addition to its LiveLAN desktop conferencing system,
PictureTel (as of this writing) has two network products shipping, and one scheduled for
release in early March 1998. LiveGateway is an H.323-compliant gateway that runs on a
Windows NT platform, and that supports H.323-to-H.320 and H.320-to-H.323 conferencing
capability. It sells for $2,395- LiveManager 3.0, which also runs on an NT platform,
performs H.323-compliant gatekeeper functions, including bandwidth control, SNMP
management, monitoring and logging, and call routing. It costs $595. PictureTel's MCU
solution, Netconference, runs on an NT server and manages up to 24 ports. PictureTel's
network elements currently recognize only Windows clients.
VideoServer (Burlington, MA) is marketing Encounter NetGate,
which allows interconnectivity between H.323 terminals and H.320 terminals, and Encounter
Gatekeeper, which performs H.323 gatekeeper functions. Both products are shipped on
standalone Windows NT workstations; VideoServer plans to integrate the two products into a
single workstation by the end of 1998. Both are priced at about $2,000 per user.
A third VideoServer product, Encounter NetServer, is
software that sells for $2,990. It can be installed on any NT server, and it adds
multipoint conferencing capability. As of this writing, its first customer ship date is
expected on March 20, 1998.
The LAN Video Gateway from Madge Networks (San Jose, CA),
introduced in the fall of 1997 at prices ranging from $11,000 to $13,000, and RADvision's
(Mahwah, NJ) OnLan L2W-323, priced from $5,950 to $12,000, are both marketed as gateway
products. However, they also come with software that can overlap with such gatekeeper
functions as bandwidth management and monitoring.
Lucent Technologies (Basking Ridge, NJ) has been another
early player in the H.323 arena. Its H.323-compliant MMCX server for Unix and PC clients
supports four to loo users per system. The MMCX takes advantage of Lucent's strong
heritage in voice communications. In addition to supporting networked videoconferencing,
the MMCX is also designed to integrate a corporate PBX system so that voice, video, and
data are all brought onto the same call management platform. Prices ranges from $28,500 to
$90,000 (including client software).
Additionally, Cisco Systems, Bay Networks, and 3Com are
adding H.323-compliant network functions, such as RSVP, to their routers. When conducting
an initial investigation of desktop video conferencing, be sure to consult with your
primary router and switch vendors to see what H.323 functions they plan to support and ask
when those functions will be available.
WIDE AREA CHOICES
Of course, the real promise of H.323 video conferencing is the potential to use the
Internet as a low-cost, wide area transport mechanism. Unfortunately, TCP/IP's inherent
unsuitability for real-time video is compounded when the video conference is carried over
the Internet.
"All H.323 solutions have a tremendous latency,"
says TeleSpan's Gold, who believes that Internet connections for video calls are simply
too unpredictable and too low-quality to be of value to business users. "Put one toe
out on the Internet, and you introduce audio latency of at least a second."
"Of course the Internet is unpredictable,"
acknowledges Forrest Milkowski, cofounder of White Pine Software. "If you're looking
for full-motion video, you better not think of H.323. But we're not trying to replace room
systems. We believe that businesses see the value of. doing more at lower levels of
quality. Being able to see the person you're talking to puts a little emotion into the
communication. It's an intangible thing, but visibility adds value and improves
communication."
Milkowski laid it all on the line recently when he
demonstrated an Internet-based video call from his office in New Hampshire to a venue in
London, video conferencing with a group of 20 reporters for the NetMeeting product
introduction. "I'd say I averaged 10 frames per second," he says. "It
wasn't video quality. But I was able to communicate better than if I'd simply placed an
audio call."
Eventually, the Internet is likely to evolve to the point
where users can reserve a certain amount of bandwidth and be guaranteed an acceptable
level of quality. But how to bill for such value-added, usage-sensitive service is still
an insurmountable challenge for Internet service providers. The telephone companies
figured out how to bill for Usage a long time ago, but that capability required years of
development and millions of lines of code in the central office switches. And it's certain
that no ISP will be willing to provide classes of service unless it can figure out how to
make money from doing so.
In the meantime, IS managers who want to use H.323 to
conference outside of local networks will probably choose to carry the traffic over ISDN
so that they can interconnect with H.320 video systems currently installed within their
company and elsewhere.
OTHER CHALLENGES
While the technical challenges inherent in implementing H.323 video conferencing are
formidable, they are not the only ones you'll need to overcome to make desktop video
conferencing work in your corporate network.
For example, H.323 provides an excellent technical solution
to help you manage network congestion and contention issues so that data continues to flow
the way you've specified. But this solution does nothing to help you decide how to choose
among competing requests for bandwidth.
"An IS manager will be required to set the guidelines
for making sure the network continues to operate," says Forward Concept's Davis.
"In some cases, that means forcing users to drop calls." Most IS managers are
not looking forward to playing such a role, and few companies have analyzed how to
prioritize bandwidth requests based on business needs.
WHAT'S NEXT
So what are you to do now, particularly if you've started to see copies of NetMeeting
populate your networks?
First, if you have a business need for desktop video
conferencing, recognize that you currently have a reasonable, non-bleeding-edge solution
over the circuit-switched network. H.320-compatible desktop video conferencing units, for
use with ISDN circuits, are rapidly dropping in price in response to greater demand and
competition.
Second, talk with your current vendors. Even before you
begin H.323 conferencing trials within your networks for document sharing and other
low-bandwidth applications, meet with your router and switch vendors to understand their
current plans to support H.323 network specifications. If you have room-conferencing
systems in place, speak with your video conferencing vendor to learn about its long-term
strategy for supporting H.323.
Plan to deploy H.323 for real-time applications like
document sharing and audio conferencing first - before rolling out video. This way you can
learn about the technology while your users learn about the technology's ability to
support their business objectives.
"Whats clear is that IP is the dominant networking
foundation, and it's going to continue to be dominant," says Davis. "So it's
also clear that products that ride on IP will be important to businesses. The [video
conferencing] industry is still just delivering bits and pieces today, but it's a good
time to think in terms of strategic relationships so that those bits and pieces eventually
come together on your network." *
Claire Tristram writes frequently about business and technology. You
can reach her at claire@tristram.com.
