Glossary
GL-6 March 2001 3160-A2-GB24-10
ICMP Internet Control Management Protocol. Internet protocol that allows for the generation of
error messages, tests packets, and information messages related to IP.
ID branch Identity branch of the DSU/CSU menu tree.
interface A shared boundary between functional units.
Internet The worldwide internetwork, which predominantly uses the TCP/IP protocol.
internetwork An interconnected collection of networks (also called an internet).
IP address Internet Protocol address. The address assigned to an internet host.
ISO International Standards Organization.
ITU International Telecommunications Union. The telecommunications agency of the United
Nations, established to provide standardized communications procedures and practices.
Before March 1993 it was called CCITT.
kbps Kilobits per second. One kilobit is usually taken to be 1,024 bits.
LAN Local Area Network. A privately owned and administered data communications network
limited to a small geographic area.
LBO Line Build-Out. The amount of attenuation of the transmitted signal that is used to
compensate for the length of wire between the transmitter and the receiver.
LCD Liquid Crystal Display. Thin glass plates containing liquid crystal material. When voltage is
applied, the amount of light able to pass through the glass plates is altered so that
messages can be displayed.
LCP Link Control Protocol.
LED Light Emitting Diode. A light or status indicator that glows in response to the presence of a
certain condition (e.g., an alarm).
link layer protocol The protocol that regulates the communication between two network nodes.
link trap A trap that identifies the condition of the communications interface (linkDown or linkUp
traps).
LLB Line LoopBack. A test in which the received signal on the network interface is looped back
to the network without change.
LOF Loss of Frame. Occurs when a DS1 terminal is unable to sy nc hro nize on the DS1 signal for
some interval.
LOFC Loss Of Frame Count. The number of LOFs declared.
loopback test A test that verifies a device’s operation by connecting the device’s output to the device’s
input.
LOS Loss of Signal. The T1 line condition where there are no pulses.
Lpbk branch Local Loopback branch of the DSU/CSU menu tree.
LQR Link Quality Reports.
manager (SNMP) The device that queries agents for management information, or receives unsolicited
messages (traps) indicating the occurrence of specific events.
master clock The master timing source used to synchronize all of the T1 and data port interfaces on the
DSU/CSU.
MB Megabyte or megabytes. A unit of memory measurement equal to approximately one
millionbytes (typically 1,048,576 bytes).