Print Servers Pull Your Printing Needs Togetherby Jay Milne
To print or not to print, that is the question. Printing is a task that most people take for granted, but it is often one of the more complex and difficult aspects of networking. There are many different ways to implement a printing solution and this article will discuss two of the most common methods: external print server devices and print server software running on a workstation or server.
Before exploring the issues to consider when selecting a print server, let's review two alternatives. One of the most common and inexpensive solutions is to connect the printer, either via serial or parallel port, directly to the file server. This is easy to implement, but it requires locating the printer near the server. This approach places the server near the wandering hands of users who might mistakenly think that rebooting the server, just as they do with their workstations, will reset the printer.
Another method is to use the built-in peer-to-peer functions of Windows for Workgroups, Windows95, LANtastic, NetWare Lite or other peer-to-peer operating systems. These products allow locally attached printers to be accessible over the network. While this is an extremely cost-effective solution--requiring no additional software and only a parallel or serial cable--it is only effective for small companies or workgroups.
The two solutions discussed here are external print servers and software print servers. External print servers are the size of a videotape, or slightly larger. They have one or more network ports and one or more output ports. All of the necessary software and drivers are stored on firmware inside the unit.
Software print servers load a program on a PC or server that has a network card in it and use the serial and parallel ports of that computer. For NetWare 3.x LANs, Novell provides a program, PSERVER.EXE, that runs on a DOS PC and can be a print server. Additionally, any Microsoft Windows NT server can be a print server. Of the two, the hardware-based solution is more common, easier to install and configure, and faster. Let's concentrate next on the issues to consider when buying an external print server.
When selecting a print server, you need to take into account the type of physical network in your environment. Is it 10BASE-T or 10BASE-2 Ethernet? Is it UTP 16-Mbps or 4-Mbps Token-Ring, or perhaps both? What about your Macintosh computers? Are they LocalTalk or EtherTalk (that is, Ethernet with AppleTalk running over it)? What about high-speed Ethernet 100BASE-T or 100BASE-VG? If you have multiple network types, be sure the print server can service all the networks simultaneously.
Do you need a serial or parallel input? These can be handy for connecting gateway systems or special workstations to the print server. Look for print servers that have all the ports active and can switch between them. Some print servers use a round-robin algorithm when servicing different interfaces--but watch out for print servers that continually service only one network if there are print jobs pending. This will lock out all other ports.
The next issue to consider is the type of input on your printer. Most low-end printers come with a serial port and a parallel port. Almost all new printers are coming out with the new bidirectional parallel port that offers higher-speed and bidirectional communications between the printer and the host.
Some print servers offer several ports, such as the Hewlett-Packard JetDirect EX Plus3, which has three parallel ports, or the Digital Products NetPrint/50, which has four parallel ports (or three parallel and one serial port). Units with m ultiple serial and parallel ports have been offered for several years, such as the Milan or Emulex print servers. This allows the print server to have multiple printers attached to it, reducing the number of network drops needed.
Check that your print server does not have any special requirements. For instance, the HP external print server requires that any printer that wants to be advertised over EtherTalk must have a bidirectional parallel port. Some print servers also offer proprietary communications ports that offer higher speed and longer distance than existing serial or parallel ports. One such product comes from Extended Systems. Its high-speed link, called ExtendedLink, allows printers to be far away from the print server while maintaining a high throughput. ExtendedLink is a combination of a transmitter and receiver that at a distance of more than 500 feet works over RJ-45 at the speed of a parallel port. Transmitters, receivers and cable need to be purchased separately.
The Protocol Soup One of the major benefits of external print servers is that they can be integration devices to allow computers on a variety of networks to share one or more printers. Watch out for print servers that promise to support a certain network operating system but require you to install additional software on the server, such as TCP/IP, to work with their unit. Also, be knowledgeable about the protocols supported on particular physical LAN interfaces. Many print servers support numerous protocols on Ethernet but only a handful of protocols on Token-Ring.
Many print servers support Unix but get the specifics of which versions are supported. Additionally, many TCP/IP print servers require a bootp server to get an IP address and other information before they can be configured for TCP/IP support. In addition, the support of lpd/lpr on the print server is important and allows it to be compatible with most Unix systems.
A good setup and management program can simplify the configuration and troubleshooting of a print serv er. One of the best setup programs available for the Windows environment is the JetAdmin utility by Hewlett-Packard. There is also a DOS version of JetAdmin and a text-based Unix version. Another good feature is the ability to sort the list of HP print servers and print it out as documentation. JetAdmin, though, only works with HP print servers.
A good setup program should have different versions, depending on the workstation operating system you're using. Check to see if DOS and Windows versions are available and if Macintosh or Unix versions are also offered.
Also, see what is required to set up the print server. Some print servers, such as the Intel NetportExpress, require you to have a NetWare server running to configure them, regardless of the network operating systems you are using. This is because NetportExpress uses Remote Boot Login to retrieve configuration information.
Another feature to consider is how the status pages of the print server are done. Some print servers print status pages in PostScript, but this only works if the print server is connected to a PostScript-compatible printer. Others require you to telnet into a box to configure them. Ideally, look for print servers that have a graphical user interface setup and management program.
Be sure that you can adjust the print server polling rate, which sets how often the print server asks the file server for print jobs. By reducing the polling time, you reduce the lag time between when a job is submitted and when it gets serviced. However, it can also increase the traffic on your network and the number of requests that your server must handle. Look also for status LEDs, which aid in troubleshooting.
Make sure that your print servers are covered by a warranty program of at least one year and that technical support is available. Some companies even provide a CompuServe forum and ftp sites to download firmware revisions.
Finally, check with friends, browse on-line services and read Network Computing for evaluations of the various prin t servers available. Word of mouth and experience are often your best sources for product information.
Jay Milne can be reached on the Internet at firstname.lastname@example.org.