Polycom ViewStation EX4000 User Manual

Page 13

Chapter 1 - About this Manual

ARJ

H.323 Admission Reject Message. This message is
from the Gatekeeper, rejecting the endpoint’s
request to connect to another endpoint.

ARQ

H.323 Admission Request Message. This message
is from an endpoint to the Gatekeeper requesting
a connection to another endpoint.

Automatic
Voice Tracking

A feature on Polycom ViewStation

systems that

allows the camera to point toward the person
speaking.

B channel

Bearer channel. B channels carry audio and video.

Bandwidth

The data-carrying capacity of a network
connection, given in terms of speed. For example,
an Ethernet link is capable of moving 10 million
bits of data per second. A Fast Ethernet link can
move 100 million bits of data per second – it has 10
times more bandwidth.

Bonding Calls

In ISDN BRI and PRI transmissions, bonding
refers to joining two or more B channels together
to get one channel whose bandwidth is equal to
the sum of the bonded channels’ bandwidths.
Using a Quad BRI interface, up to 8 channels may
be bonded. T1 allows up to 23 channels to be
bonded, and E1 allows up to 30.

BRI

ISDN Basic Rate Interface. Provides two B
channels and one 16 Kbps D channel (2B+D) for a
total of 144 Kbps, 128Kbps of which is available
for the audio and video content of the call.

Bridge

A device that passes packets between network
segments that use the same communications
protocol. If a packet’s destination is within the
sender’s own network segment, the bridge keeps
the packet local. Otherwise, the bridge passes the
packet to the network backbone. Also, in
videoconferencing, a Multipoint Control Unit. See
MCU.

Broadcast

A one-to-many transmission that can be received
by anyone connected to the network.