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.
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