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Used to tell directly connected neighbors that a router is still up
and functioning.
local area network: Broadly, any network linking two or more com-
puters and related devices within a limited geographical area (up to a few
kilometers). LANs are typically high-speed, low-error networks within a
company. Cabling and signaling at the Physical and Data Link layers of the
OSI are dictated by LAN standards. Ethernet, FDDI, and Token Ring are
among the most popular LAN technologies. Compare with: MAN.
LAN emulation: The technology that allows an ATM network to
operate as a LAN backbone. To do so, the ATM network is required to pro-
vide multicast and broadcast support, address mapping (MAC-to-ATM),
SVC management, in addition to an operable packet format. Additionally,
LANE defines Ethernet and Token Ring ELANs. See also: ELAN.
LAN switch
A high-speed, multiple-interface transparent bridging mecha-
nism, transmitting packets between segments of data links, usually referred
to specifically as an Ethernet switch. LAN switches transfer traffic based on
MAC addresses. Multilayer switches are a type of high-speed, special-
purpose, hardware-based router. See also: multilayer switch and store-and-
forward packet switching.
Link Accessed Procedure, Balanced: A bit-oriented Data Link layer
protocol that is part of the X.25 stack and has its origin in SDLC. See also:
and X.25.
Link Access Procedure on the D channel: The ISDN Data Link layer
protocol used specifically for the D channel and defined by ITU-T Recom-
mendations Q.920 and Q.921. LAPD evolved from LAPB and is created to
comply with the signaling requirements of ISDN basic access.
Broadly, the time it takes a data packet to get from one location to
another. In specific networking contexts, it can mean either 1) the time
elapsed (delay) between the execution of a request for access to a network by
a device and the time the mechanism actually is permitted transmission, or 2) the
time elapsed between when a mechanism receives a frame and the time that
frame is forwarded out of the destination port.
Copyright ©2001 SYBEX , Inc., Alameda, CA