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Viewpoint
VBX Small Office Server
The
Viewpoint VBX� Small Office server is designed to meet the
needs of the modest-size organization with a requirement for
leading-edge video on a limited budget. This server can manage
up to 16 clients. It consists a tower-configuration PC running
the Windows NT 4.0 operating system. The PC is based on a
passive backplane with ISA and PCI card slots, and a Pentium
CPU on a card. Codecs for wide-area interface may be mounted
within the server.
Each
small office server can handle up to 32 one-way or 16 two-way
users. Two Viewpoint VBX� control cards are included in the
configuration. VBX cards are full-length ISA cards that plug
into standard ISA slots in the passive backplane. External
VBX connections from each card are located at the backplate
of each card. DIP switches on each card set the card address
to allow the software to control the card.
The
Viewpoint VBX� Server software running on the PC performs
the following functions:
- Communicates
with clients and other servers
- Maintains
a database of installed hardware and connected users
- Controls
the flow of video and audio through the switch
- Logs
the system usage for management and billing purposes
Software
for the management of the Codecs runs as a separate process,
communicating directly with the server software. Control of
Viewpoint VBX�-based communications is performed using the
existing LAN infrastructure. The WorkFone VBX client software,
running on an individual workstation, communicates with the
server software, running on the VBX Server using the TCP/IP
protocol. Messages passed from client to server include Dial
User, Get Directory Listing, and Hang Up. Messages typically
use only a few bytes (a directory listing may use a few hundred
bytes), so there is virtually no impact on other LAN traffic.
Audio
and video data travels off the LAN. Because video and audio
are passed over dedicated UTP wiring, there is no effect on
network data traffic. The Viewpoint VBX� makes use of spare
Unshielded Twisted Pair (UTP) wiring for distribution of video
and audio. Each twisted wire pair can carry both video and
audio in one direction up to 3,500 feet. Most installed UTP
cabling includes four twisted pairs (a total of eight wires).
Of these, only two pairs are used by 10BaseT Ethernet networks,
leaving two unused pairs. Using these two spare pairs, the
VBX Server can implement bi-directional video and audio communication.
In addition to these spare wires, many installations run multiple
four-pair UTP cables to each destination. Even if no UTP cabling
is available in your facility, UTP cabling is easier and much
less expensive to install than coaxial (coax) cable. Like
10BaseT Ethernet networks, Viewpoint VBX UTP connections use
a hub-and-spoke topology where each user is wired directly
to the VBX Server.
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