LPR/LPD is the printing protocol most commonly used in TCP/IP networks. LPR/LPD is used extensively on university and business campuses where AS400, UNIX, and mainframes systems are common.
The current generation of mainframe printing and business workstation operating systems supports TCP/IP and LPR/LPD. It is a computer-to-computer printing method, rather than PC-to-PC.
The LPD Protocol Specification is documented in RFC 1179, Line Printer Daemon Protocol, dated August 1990, edited by L. McLaughlin III, and downloadable.
Definition of LPR
LPR stands for Line Printer Requester; it's the part submitting the requests.
Definition of LPD
LPD stands for Line Printer Daemon; it's the part that receives and processes the request. A "daemon" is a server or agent.
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Easy, Platform-Independent Protocol
LPR/LPD is a platform-independent printing protocol widely used on the Internet for remote printing that allows multiple platforms to print to the same printer without any extra configurations.
Advantages of LPR/LPD Protocol
- Simple to implement, which implies it's a good approach.
- Supports queueing, spooling and ordering; handles network and/or system interruptions.
- Using LPD/LPR protocol is inherently compatible with the majority of UNIX and other systems that implement LPD services.
- Unlimited number of queues.
- Control file contains information that can be used for various implementations.
Comparison to FTP
- Everyone knew the password, which led to inappropriate interactive use
- Old trash accumulated since it was hard to control
- Hard to identify the sender or recipient of a file