11.5. Network Print Server Boxes

A network print server is usually a box (external model) or card in a printer (internal model) which has a network connection to a TCP network and software to implement a LPD print server. If it is an external model, The parallel or serial port of the printer is connected to the box, and the print server may support multiple printers. If it is an internal model, the server is usually nothing more than a Network Interface Controller and a ROM containing software that the microprocessor in the printer uses.

The print server may support multiple printing protocols, such as RFC1179 (TCP/IP printing using the LPD print protocol), Novell Printer Protocols, SMB print protocols, and AppleTalk protocols. One of the observed problems with Network Print servers is that while they can usually support one protocol and one user at a time quite well, when you try to use multiple protocols and/or multiple users try to transfer print jobs to the printer, the printer may behave in a very odd manner. Usually this results in a printer failing to finish a job currently being printed, and unable to accept new jobs.

Several of the newer models of print servers have Simple Network Management Protocol (SNMP) agents built into them, and can provide detailed information about their internal functions. By using a SNMP manager such as SunNetmanage or HP-Openview, you can monitor your network printers activities.

I recommend that you use only a single protocol to send jobs to the printer. If you can, I also recommend that you use a print spooler and have only a single host system send a job to the printer.

My best advice on connecting to network printers is not to use the the built-in LPD server, but to use the direct TCP/IP connection to the print engine. Usually this is done to particular TCP/IP port on the printer. For the HP JetDirect and other HP products, this is usually TCP port 9100.

Once you have the direct connection, you can now use various filters to preprocess the print job, insert PJL and PCL commands, or convert text to PostScript or PCL for better print quality.