What is LPR/LPD?

What is LPR/LPD?

LPR/LPD is the printing method most commonly used in TCP/IP networks. It is in use on university and business campuses where UNIX, AS/400 and mainframe systems have been in place for a while; the new generation of operating systems, for both mainframe and desktop, now support TCP/IP and LPD as well. It is a computer-to-computer printing method, rather than PC-to-PC.

The LPR/LPD protocol is broken into two parts, LPR and LPD. The standard LPD port is 515.

LPR is an acronym for Line Printer Request; this is the part that submits the print request. LPR is the client part of the protocol and is sometimes confused when used on a mainframe. Any system submitting requests via an "LPR client" is a client. INTELLIscribe is an LPR client.

LPD stands for Line Printer Daemon; this is the piece that receives and processes the request. A "daemon" is a server or agent. RPM is a LPR/LPD server. This component is often refered to as the "LPD service".

The phrase "LPD printing" refers to the setup or process required to print to an LPD server, like RPM. Often what people have in mind is system of organizing their print requirements into LPD print queues. For instance a queue named "printronix132" might be setup to print 132 column text to a printronix printer. It's easier to keep your work organized if you are systematic and print queue names certainly give you that opportunity.

The phrase "LPR printing" is very closely related, and often refers to using an LPR capable program on your system to send print jobs to an LPD server.

The LPD Protocol Specification is documented in RFC 1179, Line Printer Daemon Protocol, dated August 1990, edited by L. McLaughlin III.

RFC stands for Request for Comments. The RFCs document Internet protocols, practices and proposed standards. They are available via anonymous FTP at http://www.ietf.org/rfc/.

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