User guide

D-2 Glossary
asynchronous Asynchronous transmission mode (ATM). A start/stop
transmission in which each character is preceded by a start signal
and followed by one or more stop signals. A variable time interval
can exist between characters. ATM is the preferred technology for
the transfer of images.
BSS Basic Service Set. A wireless topology consisting of one Access
Point connected to a wired network and a set of wireless devices.
Also called an infrastructure network. See also IBSS.
Captive Portal A browser-based authentication mechanism that forces
unauthenticated users to a Web page. Sometimes called a
‘reverse firewall’.
CDR Call Data (Detail) Record
In Internet telephony, a call detail record is a data record that
contains information related to a telephone call, such as the
origination and destination addresses of the call, the time the call
started and ended, the duration of the call, the time of day the call
was made and any toll charges that were added through the
network or charges for operator services, among other details of
the call.
In essence, call accounting is a database application that
processes call data from your switch (PBX, iPBX, or key system)
via a CDR (call detail record) or SMDR (station message detail
record) port. The call data record details your system's incoming
and outgoing calls by thresholds, including time of call, duration of
call, dialing extension, and number dialed. Call data is stored in a
PC database
CHAP Challenge-Handshake Authentication Protocol. One of the two
main authentication protocols used to verify a user's name and
password for PPP Internet connections. CHAP is more secure
than PAP because it performs a three-way handshake during the
initial link establishment between the home and remote machines.
It can also repeat the authentication anytime after the link has
been established.
CLI Command Line Interface.
Collision Two Ethernet packets attempting to use the medium
simultaneously. Ethernet is a shared media, so there are rules for
sending packets of data to avoid conflicts and protect data
integrity. When two nodes at different locations attempt to send
data at the same time, a collision will result. Segmenting the
network with bridges or switches is one way of reducing collisions
in an overcrowded network.
Datagram A datagram is “a self-contained, independent entity of data
carrying sufficient information to be routed from the source to the
destination computer without reliance on earlier exchanges
between this source and destination computer and the
transporting network." (RFC1594). The term has been generally
replaced by the term packet. Datagrams or packets are the
message units that the Internet Protocol deals with and that the
Internet transports.
dBm An abbreviation for the power ratio in decibels (dB) of the
measured power referenced to one milliwatt.
Decapsulation See tunnelling.
Term Definition