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Glossary
See xTU-R.
ITU-R
International Telecommunication Union Telecommunication Standardization Sector. ITU-T is the
ITU-T
telecommunication standardization sector of ITU and is responsible for making technical
recommendations about telephone and data (including fax) communications systems for service
providers and suppliers.
J
In telecommunications, analog communication line distortion caused by the variation of a signal from
jitter
its reference timing positions. Jitter can cause data loss, particularly at high speeds.
L
local-area network. High-speed, low-error data network covering a relatively small geographic area
LAN
(up to a few thousand meters). LANs connect workstations, peripherals, terminals, and other devices
in a single building or other geographically limited area. LAN standards specify cabling and signaling
at the physical and data link layers of the OSI model. Ethernet, FDDI, and Token Ring are widely used
LAN technologies. Compare with WAN.
light amplification by stimulated emission of radiation. Analog transmission device in which a
laser
suitable active material is excited by an external stimulus to produce a narrow beam of coherent light
that can be modulated into pulses to carry data. Networks based on laser technology are sometimes
run over SONET.
light emitting diode. The lights indicate status or activity of electronic equipment.
LED
See LED.
light emitting diode
The speed at which data is transferred over a particular line type, expressed in bps.
line rate
Network communications channel that consists of a circuit or transmission path and all related
link
equipment between a sender and a receiver. In a transmission network, a link is a point-to-point
connection between adjacent nodes.
See LAN.
local-area network
A logical entry to a server machine. Logical ports are mostly invisible to the user, though you may
logical port
occasionally see a URL with a port number included in it. These ports do not refer to physical
locations; they are set up by server administrators for network trafficking.
A diagnostic test that returns the transmitted signal to the sending device after the signal has passed
loopback
through a network or across a particular link. The returned signal can then be compared to the
transmitted one and the discrepancies between the two can be used to trace the fault. When you are
trying to locate a faulty piece of equipment, you can repeat loopbacks, eliminating satisfactory
machines, until the problem is found.
Cisco 6260 Hardware Installation Guide
GL-18
OL-2365-02
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