IP videoconferencing arrives
- By Michelle Speir
- Apr 03, 2000
Testing by Lisa L. McNair, Michelle Speir and Ania Bernat
What's the latest videoconferencing buzz? To sum it up in two letters:
Before the Internet swept the world, videoconferencing systems were
limited to running over Integrated Services Digital Network (ISDN) lines.
But now that IP, or Internet Protocol, is becoming established as the networking
standard of choice, videoconferencing vendors are stepping up to the plate
with IP-based systems. The only problem is the IP network infrastructure
isn't quite ready yet.
The primary issue is that many of the lines that support IP networks,
such as the Internet and intranets, offer a pipeline that is too small to
handle the bandwidth required for TV-quality video and audio transmission.
Also, some standards have not yet been ratified, such as one for remote
camera control. For now, if you want to control a camera at a remote site,
you'll have to use ISDN.
Further, IP only supports voice- activated video for multipoint conferences.
So, unlike ISDN systems, which allow viewers to see multiple locations at
once, IP systems can only show one location at a time.
In addition to these quality-of-service issues, many would-be customers
are afraid that videoconferencing equipment will bog down their networks,
if not crash them completely.
Indeed, some networks may require an upgrade in order to run IP video-
conferencing. Vendors generally recommend using switched Ethernet, which
provides a dedicated data pipe to workstations rather than sharing the bandwidth
with other network traffic, and Fast Ethernet to the desktop, which supports
100 megabits/sec transfer rates.
The good news is that, slowly but surely, videoconferencing over IP is becoming
a viable reality. A worldwide standard dubbed H.323 enables different brands
of systems to communicate with one another. (The ISDN equivalent of this
standard is called H.320.) H.323 tells any IP device (including network
routers and gateways) how to compress and transmit audio and video over
a network that wasn't designed for it.
To assess the current state of IP videoconferencing, we looked at systems
from the three largest U.S. vendors: PictureTel Corp. (which partnered
with Intel Corp. and is the exclusive distributor of the Intel TeamStation
System), Polycom Inc. and VTEL Corp.
We chose a price point of $10,000 and under, which buys a system in what
is considered the low end of the market. Therefore, the standard systems
we chose lacked extras such as software that allows administrators to manage
the devices remotely. However, all are upgradeable to handle features such
as dual cameras and dual monitors. Management software and other software
upgrades can also be purchased as add-ons.
The systems we chose fell into two general categories. Polycom's ViewStation
SP fits into the conferencing appliance category. This type of system is
typically composed of a set-top box coupled with a television or other type
of National Television Standard Code (NTSC) display and is used for presentations
and small group meetings.
The Intel TeamStation System and VTEL's Galaxy 725 MT, on the other
hand, are collaborative computing systems that are PC-based. These systems
display the video in one portion of the computer screen and the collaborative
conferencing tools in the other.
Conferencing no longer is just about seeing people on a screen. Thanks
to a standard called T.120, participants can send files, share applications
and use a real-time whiteboard function to share and explain ideas. Since
we looked at low-end systems, we did not test T.120 functionality because
only the PictureTel system included it as a standard feature. However, the
other two systems can be upgraded to accommodate T.120.
There is good news about all three systems. First, none of them requires
an IS manager's expertise to set up. Hardly videoconferencing experts, we
were able to accomplish each setup in about 30 minutes or less.
Next, all of the products feature reasonably intuitive software interfaces.
In some cases we had to consult the documentation to figure out a function
or two, but once we looked them up, we were able to breeze through with
no trouble. All of the software featured handy functions, such as dialing
Video and audio quality were good across the board. The video appeared smooth,
and lips synchronized well with voices. When on-screen subjects made large
movements, however, blurring and jerkiness resulted.
One feature of our test plan prevented us from determining the specific
source of this degradation. Because we had only obtained one set of video-
conferencing equipment from each vendor, we used different vendors' equipment
on different ends of the connection.
This means, of course, that we can't be sure whether the degradation occurred
primarily on the sending or receiving end. But VTEL's 512 kilobits/sec line
rate (the highest of the products we tested), if used on both ends of the
transmission, should result in generally smooth video. Expect some jerkiness,
however, if your transmission rate dips to 256 kilobits/sec.
However, the important fact to note is that we didn't run into any trouble
getting all three systems to communicate with one another over our network.
Our testing proved that the H.323 standard really works, enabling different
videoconferencing brands to work together seamlessly.
Another significant finding was that placing calls during the day, when
network traffic was high, did not slow down our 10Base-T Ethernet network
at all. Neither the 50 to 60 users on the system nor system administrators
noticed anything unusual.