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Appendix A: Glossary
A-9
LLC. The Logical Link Control layer is one of two sub layers of the Data-Link layer and is con-
cerned with managing traffic (flow and error control) over the physical medium. The Logical Link
Control layer identifies a line protocol, such as SDLC, NetBIOS or NetWare, and may also as-
sign sequence numbers to frames and track acknowledgements.
The other Data-Link sub layer is the Media Access Control layer.
LocalTalk. A low-speed (230.4Kbps) local area network standard developed by Apple Com-
puter. Normally used with the AppleTalk protocol.
Logical. Refers to conceptual rather than physical. For example, a computer may have a single
physical connection to the network (an Ethernet adapter card), but may have logical connections
to many different devices on the network.
Lpd. Line Printer Daemon. A program that runs on a host computer or a dedicated print server
that allows other host computers to print jobs on that computer or print server. IntelliBar print
servers use lpd to allow printing from computers on the network.
lpd-Plus. A feature of IntelliBar print servers that allows the user to define multiple services, each
with a different setup and reset string. For example, a user could have one service for landscape
printing and another for portrait printing. Also called logical printers.
LPR. Line printer. The Unix print command. This does not actually print files but rather copies
(or links) them to a spool area from where a daemon copies them to the printer.
Lpq. A Berkeley UNIX command for obtaining the status of printers.
Lpstat. An AT&T UNIX command for obtaining the status of printers.
LPT. Line printer. See LPR.
LPT1 The primary parallel port on a PC. Many networking programs allow transparent printing
to network printers by accepting output intended for LPT1 and redirecting it over the network.
LU. Logical Unit(s). LUs are specialized IBM network service program products such as Cus-
tomer Information Control System (CICS) and Information Management System (IMS). LU2 is
used for host communication sessions with workstations such as 3270s. LU 3 is defined for host
sessions driving line printers. These include emulation of LU2 (IBM 3278/3279 Model 2, 3, 4, or
5 display) and LU1/LU3 (IBM 3287 host printer) type devices. IPDS printers have to be de-
fined as LU type 1 in the VTAM log mode. In IBM's SNA, a logical unit (LU) identifies an end
user in an SNA network. By end user, IBM means either a human being that is interacting with
the network or an application program that is indirectly representing such an end user. Two logi-
cal units that communicate depend on physical connections being established through associated