Andrey Borzenko
Today, printers directly connected to the network have become traditional office equipment. They provide fast printing and easy installation regardless of location, which is so important for network administrators. However, in organizations with a small and medium-sized local area network, the most common option for joint network printing remains personal printer connected to one of the PCs (Fig. 1). The main advantage of this option is economy. However, keep in mind that this method of printing uses the resources of the PC to which the printer is connected, and the performance of the computer is significantly reduced. So with large volumes of network printing, it becomes very difficult to use this PC for its intended purpose. Dedicating one computer only for network printing, as well as purchasing a dedicated network printer, often unjustifiably financial point vision, especially if the print volumes do not exceed the capabilities of the printing device used. In solving this problem, the so-called print servers, or print servers, are designed to help.
Print servers are small network devices, to which one or more printers can be connected (Fig. 2). They are of two types: external and internal (Fig. 3). The latter are made in the form of a board and, as a rule, can only be used with certain printing devices. The most noticeable limitation of internal NICs is that a specific printer must support them. And this means that if the printer was manufactured before the advent of such devices, or if the printer is new, but internal maps it does not support, you will have to apply external device network printing.
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Rice. 2. Print server for two printers. |
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Rice. 3. External and embedded print servers. |
In addition, the internal board serves only one printer. External print servers are able to serve multiple printers at the same time, and thus save on additional ports. When single device works with many printers, it also reduces configuration needs and required resources. For example, one IP address is enough for each of the printers, while printers with internal board Everyone will have to allocate a separate address.
Often internal network boards are limited in the number of supported network protocols and their simultaneous support: it happens that desired protocol is not supported or the two protocols cannot work simultaneously.
An external print server provides transparent, network printer sharing. As well as network computer with a printer connected to it, the external print server has its own network connection, and the printer (or printers) connects directly to the server. In this case, there is no need to spend money on the purchase and maintenance of a relatively expensive PC - instead, an inexpensive, small-sized, easy-to-use device is used.
Benefits of External Print Servers
Print servers are generally recommended to be installed in medium and large networks where required remote control printing devices. Their use is especially effective in cases where the network has a lot of printers located on different floors and even in different buildings, and it is necessary to provide the administrator with maximum control options, and the user - maximum convenience for working with them.
Saving money
To print from a computer or file server with a printer attached, you need to have that computer or server, and they are quite expensive. Costs increase significantly if many printers that need network access are distributed throughout the office. Even the simplest computer is significantly more expensive than a powerful multi-protocol print server, the latter supporting multiple printers at the same time. In addition, the print server allows you to reduce the time spent on support and service (maintenance of a computer requires significantly more time).
Unloading the main processor
Processing print jobs takes up a lot of CPU time on the computer to which the printer is connected. If the PC is performing other tasks or providing files to general access, printing can significantly affect its ability to perform other tasks. Printing performance also leaves a lot to be desired when the computer is running multiple, processor-intensive jobs at the same time.
Cause heavy load on the processor lies in the so-called software character-by-character I/O mechanism. Its essence is that when the server sends a print job to the printer, a processor interrupt is initiated for each character. It does not matter which computer is used - an outdated XT-box or the most fast car based on Pentium 4. Server requirements increase significantly if it serves multiple printers.
The print server uses DMA (Direct Memory Access) instead of software character-by-character I/O. In this case, the processor interrupt is triggered only for entire data packets. Thus, the print server not only offloads the computer or file server, making them more efficient in other tasks, but also allows you to achieve faster network printing.
Convenient accommodation
When connecting printers to a computer or file server You don't have to choose their location. And since servers, for example, are usually located in a secure, specially air-conditioned room or closer to the system administrator, they are often inaccessible to most users, who have to make long "walks" to pick up documents sent for printing. Network print servers, on the other hand, allow printers to be placed anywhere on the network, exactly where they are needed most. Thanks to small size such devices can be connected directly to the printer or placed in places where they do not interfere with anyone.
Additional job processing
Often in a heterogeneous network environment, print jobs created on different operating systems or networks require additional processing before sending to a particular printer. For example, many print jobs created on UNIX require "carriage returns" to be inserted at the end of lines, otherwise the printer prints the text in a "ladder". Another standard pre-treatment requirement is printing title page for each job so that users can find their documents in the printer's output stack. In many cases, the printer needs to be configured differently for different users.
This feature is often provided on print servers using virtual printer technology, allowing significant savings on the purchase of additional printer devices. In this technology, special virtual printers configured directly on the print server. Users submit their jobs to the virtual printer, and the jobs are pre-processed according to predefined conditions. For example, one virtual printer can be used to insert carriage returns in jobs from computers running UNIX, another to convert ASCII jobs to PostScript for users whose applications do not support this format, a third to prioritize jobs for users who need provide a certain level of security. In addition, all virtual printers can be configured to print a banner page. The advantage of the print server is that all these virtual printers are located on the same server and all users are served by one physical printer.
Management options
It is vital for network administrators to know what is happening on the network. When the server is tasked with printing, it generates messages about the status of print jobs, the number of pages printed, and notifications about printer problems such as unavailable, paper jammed, or missing. These messages are sent directly to the network administrator via e-mail or logged to the system log.
In addition, print servers often support software management. SNMP protocol, allowing full control over standard SNMP applications such as Hewlett-Packard's OpenView, Sun's SunNet Manager, or Castle Rock's SNMPc.
Print Server Capabilities
Print servers are currently produced by companies such as Axis Communications (http://www.axis.com), Digi International (http://www.digi.com), D-Link Systems (http://www.dlink .com), Hewlett-Packard (http://www.hp.com), Intel (http://www.intel.com), Lantronix (http://www.lantronix.com), Lexmark (http:/ /www.lexmark.com), Microplex Systems (http://www.microplex.com), NetGear (http://www.netgear.com) and others (Fig. 4). In terms of dimensions, these devices are slightly larger than a conventional video cassette. Each has a power supply connector, a 10/100 Mbps RJ-45 Ethernet jack, and multiple printer ports (parallel and serial). Some devices have built-in hubs. Typically, all print servers can work with text printers and PostScript printers at the same time. Most printers on the market are compatible with these servers, but there are some that do not work with them. These are inexpensive printers such as the HP DeskJet 700, 820, or 1000. They use Windows 95/98 to perform most image rasterization functions and only function when connected directly to a PC running one of these operating systems.
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Rice. 4. Print server D-Link DP313. |
With embedded Web servers, all print servers can be configured using a browser. New devices usually support the IPP (Internet Printing Protocol) protocols. Automatic IP address assignment and intuitive naming of DHCP and WINS/DNS enabled printers makes them easy to install and configure. Each device can perform a test print or display a status printout containing information about its IP address, active protocols, the number of documents in the print queue, the types of printers connected to it, and other information. Some print servers are equipped with special button test, which, when clicked, displays a diagnostic printout with information on the printer. In most cases, the print server is able to determine the type of printer connected and the required network protocols. Automatic recognition speed and media eliminates the need to configure these settings during installation.
Typically, each print server comes with a CD-ROM containing configuration and management utilities. Because the new print servers are open architecture, they can be updated by downloading new firmware stored in flash memory. This allows you to adapt print servers (according to at least, for some time) to ongoing technical changes.
To network servers and client PCs could work with the print server, they must be properly configured with new network printer drivers installed on them. There are two main configuration methods, one is to create a virtual local printer port (on a PC or server) using software supplied by the print server manufacturer, and the other is to use the new IPP protocol (if the client OS supports it). Some print servers have special means, which create an installation disk for a new network printer containing the driver for this printer, as well as information about the IP address of the print server and the password for accessing this printer. You can install the printer driver in another way - using the IPP protocol.
Speed up printing
The printer is the bottleneck in almost any printing configuration. Print servers are capable of delivering speeds much faster than standard parallel port computer, and in most cases deliver data faster than a conventional printer can handle. For example, Microplex print servers are equipped with parallel ports with a performance of more than 200 thousand characters per second. A standard computer parallel port transmits approximately 30,000 characters per second.
Here it should be emphasized once again that print servers support most of the known printing devices - from the latest lasers to the oldest dot matrix printers. In addition, any printing languages are supported, such as PostScript, PCL, HP-GL, and others. The print server doesn't care what type of data passes through it. It simply sends data transparently to the connected printer or printers. The only exception is when special data processing is required, such as conversion from ASCII to PostScript. In this case, the print server only looks at the beginning of the data to determine if a conversion is required.
Generally speaking, in order to evaluate the performance of printing, it is necessary to know the "bottlenecks" of this process. So, when preparing a print job word processor takes time to convert the document from its own internal format to a printer format such as PCL or PostScript. The conversion process depends on the size of the document and the performance of the word processor when performing this operation; it can be fast or take a fair amount of time. The conversion time is also highly dependent on PC performance. The time it takes to transfer a job from a word processor to the print queue is called paging time. It is determined by factors such as performance application program when moving data to a printer port (or spooling to print), as well as network performance when transferring data for printing and queuing them. The time that a print job waits in the print queue is called the wait time. It depends on a number of factors, including the number of jobs in front of it, their size, the speed of the server, and how it is used. The print server periodically checks the print queue, if it exists at all, to see if there are jobs to print. If there is such a queue, and the printer is online and ready to receive, then the print server will begin moving the job from the queue to the printer. This process is called de-paging or queuing, and the time it takes to move the entire print job to the printer is called de-paging time. Factors that govern paging time are the rate at which the print server can purge data from the print queue and the rate at which it sends that data to the printer. Another key factor- the speed at which data is received by the printer.
As practice shows, it is the paging time that often has the maximum impact on network system print. In a well-organized network printing system, the waiting time is usually short, since the print job is often the only one in the queue. In this case, once the word processor has finished paging, the only thing left for it to do is print, which will take depaging time, depending on the print server.
Print servers serve all jobs on an equal basis on a FIFO basis: first in - first out (First In - First Out), i.e. there is no preference for individual computers or networks. Each I/O port usually has its own queue, which is processed independently of other ports' queues. Thus, a print server with four I/O ports (two parallel and two serial) can support four queues, each serving a different printer. The ports support printing simultaneously without the risk of mixing or job loss.
At any given time, the print server stores only a few kilobytes of data per I/O port, and the rest of the data is stored at the job source. There are simply no print servers on the market today that can fully spool print jobs, so the source computer is always involved in spooling jobs. In most cases, this operation is very fast.
Access control
If the print server is not equipped with security features, then no matter how many security enhancements are hidden in the network OS, the network administrator receives open system, where there is no way to prevent access by users without sufficient rights. The ability to restrict printer access has significant potential benefits. In particular, unauthorized use of the printing device leads to increased maintenance costs and expendable materials. If the printer prints unauthorized jobs, then it is not available for urgent business projects that have tight deadlines. The consequences of poor control over printer usage can be more severe if print servers serve printers that print receipts, invoices, and other accounting documents. In many cases, access control helps to prevent serious negative consequences that unauthorized printing in institutions that work with confidential documents can entail.
In many cases, network administrators organize a centralized print job queue. Users submit jobs to a centralized queue on the file server, which then forwards those jobs to the print server, which in turn forwards the job to the printer. With this discipline, system administrators can centrally manage all user print jobs. This allows you to use such network operating system features as automatic download printer driver when connecting to a queue, while maintaining the performance and location freedom of print servers.
In some situations, sending print jobs to a centralized queue is either not possible or efficient. An example is remote office, equipped only with workstations and connected to the headquarters by a slow communication channel. It is often not possible to create a centralized print queue, either because the file servers are overloaded or for other reasons. AT similar situations it is reasonable to have workstations print directly to print servers. Print servers support both sharing and direct printing.
Because the network OS security features can restrict access to only the file server's print queue, any computer connected to the network can send a print job directly to the print server without being controlled by the network OS. A reasonable solution in this case is to equip the print server itself with security measures.
One solution to the problem of unauthorized access is the use of Intel password protection technology. This technology complements the security features found in most network operating systems. A security check is performed whenever a user attempts to print directly to a network printer, bypassing network OS security. For example, with the Intel NetportExpress 10 and 10/100 print servers, administrators can set a password to access any connected printer. In an environment with sharing printing, for example, when users submit print jobs to a queue for Windows server NT, the administrator can configure the NT server settings to forward jobs to the print server with a password. The file server is the only computer that needs to know this password. The administrator controls access to the print queue using normal network OS security. It should also be noted that in a situation where workstations print directly to a printer, there is no centralized print job queue on the network and the network OS does not control access to the print server. Anyone can use the printer. This technology overcomes this limitation by replacing the security features of the network OS. Only those users who know the corresponding password can print documents to a specific printer from their workstations. If a work station specifies an incorrect password, the print job simply fails, as if the printer were not connected to the network at all. So, if the administrator has three printers connected to the same print server, then any of them (or all at once) can be provided with a unique password. For example, if a monochrome laser printer and a color inkjet printer are connected to the print server, then access to the laser printer can be allowed to everyone, and access to the color inkjet printer restrict with a password. Printer passwords can be used in UNIX systems, Linux, Windows NT, Novell and even AS/400.
Today, for most new devices, you can limit network access to them and to their individual printer ports. Such a restriction may be required, for example, if printers contain special paper ( different kind forms, letterheads, etc.) or if you want to ensure printing only through a file server (running under Linux control, NetWare or Windows NT). If the print server is configured to allow access only to the file server, then users will not be able to print bypassing the file server by communicating directly with the print server. Print servers also have the ability to restrict access to their Web interfaces with a password.
Protocol support
In heterogeneous network environments, administrators must maintain multiple various services printing and protocols. Print servers allow multiple network users to print to the same printer using different network protocols. Thus it is great way reduce the cost of a job. Users can use the same printer even if they are working on different platforms. Modern servers Printers generally support TCP/IP, IPX, DLC/LCC, AppleTalk/EtherTalk, NetBIOS/NetBEUI, LAT protocols, so they can be used even in mixed environments. As for printing protocols, they usually include LPD, RSHD, FTPD, direct connection, PSERVER, RPRINTER, LPD, print manager, etc.
With the constant growth of computer networks, the process of managing print in them is noticeably more complicated. Print servers are designed to solve this problem. And the more "smart" they are, than more features begin to take over, the easier it will be for the administrator to solve network problems, and users will be able to work much more efficiently. Per last years There has been a fundamental change in online printing, and there is no end in sight to this process of change. Companies want enterprise-scale remote printing solutions and network administrators are interested in tools that would simplify management and provide greater centralization of printing processes.
As soon as the first local network appeared (and printers appeared even earlier), a very sensible idea arose - you can organize access for several or all computers included in the "local" at once to a common printing device. But obviously, this requires something between the network and the printer. This "something" is the print server. You can, of course, immediately purchase a printer with the ability to direct connection but for this option you will have to pay at least the equivalent of $ 50.
Like many network concepts such as a firewall or gateway, the print server can be software or hardware.
The software print server is implemented on the basis of conventional computer A to which one or more printers are connected locally. By means of the operating system, all other computers and their users, if they have the appropriate access rights, are given the opportunity to work remotely with these printers. This principle of implementation of the print server is most often used in homes or small offices.
A hardware print server looks like a small box (usually the size of a large ashtray) with several I / O ports. Minimum necessary set ports - one standard RJ-45 network port and one (a device with an LPT port, due to its obsolescence, is already extremely difficult to find). Manufacturers equip more expensive models with several USB connectors, so that the server can serve multiple printers at once. AT recent times many manufacturers are starting to promote this type of device as a wireless print server. WiFi adapter this device intended to replace wired network connection and get rid of the need to extend the extra to the print server How much such a solution is justified in a stationary office in the immediate vicinity of a no less stationary printer is up to the administrator to decide.
In addition, print servers are increasingly being built into low-cost Internet routers designed primarily for home use(SOHO market segment - small office, home office). Everything said above and below about hardware print servers is true for these devices.
Now it's time to consider all the pros and cons of each method of implementing network access to a local printer.
The main advantage of a software print server is the absence of the need to purchase some new, highly specialized equipment, the cost of which can range from 40 to several hundred dollars. There is a computer, there is a printer, there is a cable connecting the printer and the computer, and there is System Administrator who knows how to make it work - that's it! Any modern operating system allows you to provide network access to any printer connected to your computer. But such a print server has one major disadvantage: with large volumes of printing (for example, in the accounting department the day before the deadline for submitting the annual report), the computer that serves as the hardware base for the software print server will spend quite a lot system resources to ensure the operation of the printer. If this computer is very outdated, which is not uncommon in the same accounting department, "slowing down" even ordinary routine tasks will be very noticeable. In addition, if we are talking not about a regular printer, but about its MFP additional features a photocopier or fax machine can only be used on the computer to which it is connected locally.
The main advantage of a hardware print server is that there is no need to allocate additional computing resources to service the print queue. Actually, this is the goal of creating all specialized devices - to transfer the execution of tasks of the same type to equipment specially "sharpened" for them. Also, some advanced models of print servers allow, when connected to an MFP, to use, say, fax or scanner functions.
But, unfortunately, not every printer will be able to work through hardware server print. The risk group includes, first of all, outdated models, as well as inexpensive devices, which are the majority in small offices. Manufacturers of print servers publish a list of supported printers on their websites and in the specifications of their devices. But, if you have already bought / borrowed / stolen a hardware print server, and only then got acquainted with such a list and did not find your printer in it, do not despair. This means that the print server manufacturer simply does not guarantee trouble-free operation of the bundle of these two devices.
"Print server"- many have probably heard this word, but do not know what it is. Let's lift the veil of secrecy and figure out what it is" print server".
To make it clearer, let's turn to history and see how printing took place before.
Long time ago when computer networks were a curiosity, and each computer worked by itself, users printed from computers to individual printers connected directly to each computer.
Time passed, computers began to be connected in a network, and one day the thought came to someone's bright head - what if you use one printer to print all computers? - in a network they are already united! No sooner said than done: a printer is connected to one computer, the rest print to it over the network. However, one serious drawback immediately emerged - if you turn off the computer to which the printer is connected, no one can print.
This is how network printers appeared - in addition to standard connectors for connecting to a computer, they have network ports, which allows you to connect them to the network directly without any computer. Thus, the printer becomes available at any time, since it is not tied to any computer on the network.
But the question is - what to do with old printers? How to make them network, unattached to a specific computer? The answer is simple: install print server!
So we come to the conclusion that print server is a device that allows you to connect a printer that does not have network port to the network. Those. to put it even more simply: print server, this is a box to which a printer is connected on one side, and a network wire on the other side.
However, it is worth noting that in nature there are also wireless print servers, i.e. instead of a network wire, they have an antenna through which they communicate with an access point and connect to the network without any wires, which is very convenient when there is a need to install a printer in the middle of a room, and network wires dragging on the floor are not allowed.
Most printers are connected to the computer via USB port, rarer (older models) via LPT port. As a consequence, there are print servers With various ports: USB and LPT; there are also combination options, when print server It has several ports, which allows you to connect several devices to it at once, and it happens that both via LPT and via USB. You can also find other devices equipped with print servers- it can be network drives(eg D-Link DNS-343), ADSL modems and other network devices.
If you decide buy a print server in Krasnodar- contact us - we will help you choose print server compatible with your particular printer, since not every print server Works with any printer models.
There are others technical solutions. One of these is the "Print Server" or print server, which is a separate network hardware- intermediate between your printer and the local network.
As you understand, both in the first considered case and with the use of a print server, the presence is required, and it does not matter what technology it is built on.
The print server was originally designed to cable networks, so the device was equipped with a connector type - RJ45; but over time versions have been developed with . There are combined models of print servers, but the minus of this option is a higher price.
If we consider the option of connecting via "Ethernet", then you will always have a chance to organize wireless access to the printer if the print server is connected to . So, first of all, it is worth starting from the current network capacities.
Like connections printing devices to a PC, and print - servers are of two types: LPT (obsolete port) and USB (popular standard). Also, like a network connection, it can be combined, and often, it makes it possible to operate.
Speaking about connecting several printers using one print server, do not forget about the pricing policy and the tasks to be solved. If you are installing a print server for a small office, then even for a group of 3 to 5 users, one printer will be enough.
Pros and cons of a print-server solution
Well, firstly, the print server gives Free access to one printing device, accepting requests to the print queue from different computers. This will not only save workspace but also the firm's cash savings.
The advantage of this connection is that you can leave the printer on and be able to print independently from other PCs on the network. When local connection to the user's computer, access to the printer disappears immediately after the OS shuts down.
This technology also has its downsides. Firstly, the user does not have minimal monitoring of the print queue, the only evidence will be an error, and the inability to resume the process.
Also, a computer on the network cannot receive notifications about the status of the equipment. Some commonplace messages are missing: ink or toner low, paper jam, paper tray empty, etc.
How to manage the "print - server"?
Like any high-tech device, the print server has firmware that provides a number of access and network settings. Regular user no changes to the configuration of the print server will be required as it comes with default settings that are sufficient in most cases.
If you need to correct current settings, then this can be done through the supplied software or through the web interface. The second is available in many models at:
192.168.0.1
worth checking out network settings your computer, since you need to be on the same subnet (255.255.255.0) and located at the same IP address to access:
192.168.0.xx
where "xx" is any number between 2 and 255.
More details about web access to the interface can be found in the manual supplied with the print server. Depending on the model you purchased, the manual may contain a number of technical features by connection.
Instead of an afterword
Print server, enough, a useful purchase, with correct use it optimizes office work. When buying this device, you should rely on a couple of things: a working printer (its connection standard is LPT or USB) and the type local network(cable or wireless connection); Having decided, you can reduce the start time!
As for larger offices, for a printing solution, it is worth considering buying a printer with a built-in network card. Such equipment combines a connection directly to the user's computer, as well as a connection to network stations. hallmark such a printer high speed processing network requests for printing, and a small percentage of failures! Minus one - the price.
For companies that have a small to medium sized LAN, a fairly common network printing option is to use a small local printer, which is connected to one of the computers on the network. The main advantage of using this option is economy. However, when implementing this option, printing uses additional resources the computer to which the machine is connected, resulting in a significant reduction in its performance. Dedicating a single computer for network printing only is costly, especially if the required amount of printing does not exceed the capacity of the printing device. The solution to this problem may be the use of the so-called print server.
The print server (print server) is small device, connected to the local network (cost from $ 40), to which they connect one or more printers(the number of connected devices depends on the type of device). Exists two types of print servers: internal and external. External print servers in most cases, they work with any device, regardless of the manufacturer, and internal exclusively with printers from the print server manufacturer. But regardless of the type of print server, it is "transparent" for operating systems and requires only correct setting parameters for the used data transfer protocols in the network.
Basically, print server models differ in the type and number of ports used to connect printing devices, network speed, dimensions, as well as the range of network protocols that it can support and, as a result, the ability to work in a "multi-operational" network (that is, a local network, to which PCs are connected. operating systems various types).
The print server comes with proprietary software that allows you to administer the work and has advanced or not diagnostic and configuration tools. Basically, this software allows you to work only with devices from the manufacturer of the print server.
Depending on the manufacturer and model of the print server there are several options for "behavior" it on the local network. When connected, some models are displayed in network environment how separate computer with connected printers. AT this case to install the printer on a work computer, the usual algorithm used to connect a regular network printer is used. In this case, there is no need to install additional software from the print server developer to the client machine. The print server can only be administered from the computer on which the configuration software has been installed. In another case, to install a printer that was connected to the print server, it is necessary to install and configure the printer on the user's computer. client side software. Wherein client program emulates local port printer on the computer.
