Line Printer Deamon protocol (LPD) supports remote printing over TCP/IP from Unix or Linux hosts. Windows server products support LPD for printing from Unix or Linux hosts. LDP is also featured in CUPS.
See RFC 1179.
References:
http://technet.microsoft.com/en-us/library/cc731857.aspx
http://www.brooksnet.com/content/lprlpd-protocol