User guide

Glossary 433
C
CDB
Configuration Data Base. A file containing a
device’s configuration information.
Class of Service
Class of Service (CoS). Class of Service is the 802.1p
priority scheme. CoS provides a method for tagging
packets with priority information. A CoS value
between 0-7 is added to the Layer II header of
packets, where zero is the lowest priority and seven
is the highest.
A overlapping transmission of two or more packets
that collide. The data transmitted cannot be used,
and the session is restarted.
Combo Ports
A single logical port with two physical connections,
including an RJ-45 connection and an SFP
connection.
CLI
Command Line Interface. A set of line commands
used to configure the system. For more information
on using the CLI, see Using the CLI.
Communities
Specifies a group of users which retains the same
system access rights.
CPU
Central Processing Unit. The part of a computer
that processes information. CPUs are composed of a
control unit and an ALU.
D
DHCP Client
An Internet host using DHCP to obtain
configuration parameters, such as a network
address.
DSCP
DiffServe Code Point (DSCP). DSCP provides a
method of tagging IP packets with QoS priority
information.
Domain
A group of computers and devices on a network that
are grouped with common rules and procedures.
Duplex Mode
Permits simultaneous transmissions and reception
of data. There are two different types of duplex
mode:
• Full Duplex Mode — Permits for
bisynchronous communication, for example,
a telephone. Two parties can transmit
information at the same time.
• Half Duplex Mode — Permits asynchronous
communication, for example, a walkie-talkie.
Only one party can transmit information at a
time.
Dynamic VLAN Assignment (DVA)
Allows automatic assignment of users to VLANs
during the RADIUS server authentication. When a
user is authenticated by the RADIUS server, the user
is automatically joined to the VLAN configured on
the RADIUS server.