3Com 3C10402B Administrator's Manual page 551

G 551
LOSSARY
Most codecs include the functions of A/D and D/A conversion as well as
compression and decompression.
COder/DECoder. A hardware circuit that converts analog audio or video
signals into digital code, and vice versa, using techniques such as pulse
code modulation and delta modulation. A CODEC is an A/D and
D/A converter.
collapsed backbone Network architecture in which the backplane of a device, such as a hub,
performs the function of a network backbone. Example: The backplane
routes traffic between desktop nodes and between other hubs serving
multiple LANs.
collision The result of two devices on a shared transmission medium, like Ethernet,
transmitting simultaneously. Both devices must retry their transmissions.
A delay mechanism used by both senders drastically reduces the chances
of another collision.
collision detection Ethernet devices detect collisions instantly and attempt to resend. This is
the principle on which CSMA/CD (Carrier Sense Multiple Access with
Collision Detection) is based and the access control method for Ethernet.
concentrator A central chassis into which various modules, such as bridging,
supervisory, and 10BASE-T cards are plugged.
congestion The result of increased network use on a LAN segment. Standard
network partitioning practices must be invoked to reduce bottlenecks
and maximize throughput speeds on the segment.
contention The method used to resolve which users gain access to crowded
bandwidth.
CO Central Office. A telephony term for the telephone company site that
houses the PSTN switching equipment.
CoS Class of Service. A collection of calling permissions that are assigned to
individual users and govern the times and types of calls these users can
make.
CPE Customer Premises Equipment. Telecommunications equipment,
including PBX systems and wiring, that is located in a user's premises.