Printer connection technology Overview (LPR & raw & appletalk)

Introduction

Network Printing connection has a significant impact on the performance and scalability of Microsoft Windows Printing server. First, it is important to know the options that can be used to connect a customer workstation to a print server. In addition, the printer port type used to send jobs on the server to the actual printer device is critical.

 

Client-server connection

Windows clients usually connect to the print server through Remote Procedure Call (RPC) or SMB service. RPC is the preferred connection type because it supports enhanced point-and-print features. SMB connections are mainly related to Windows 98 and earlier systems. You can create a local printer port and redirect it to printer sharing on the Windows Printer server to establish a printer connection on a Microsoft Windows-based client. HTTP provides another available connection type from the client to the server. Windows 2000 and Windows Server 2003 implement the Internet print protocol (Internet
Printing Protocol, iPP) standard version 1st. This protocol allows the client to view the printer and its status, connect to the shared printer, and use the HTTP Print Provider to submit the job.

 

Printer Port Selection

Microsoft Windows Server 2003 provides built-in support for the following network port types:

•	Standard TCP/IP Port Monitor
•	Lpr print monitor
•	Appletalk printing Monitor
•	HTTP print monitor

Note:Hewlett-Packard printer port is unavailable in Windows 2003

Windows Server 2003 also supports the following local printer ports:

•	USB 1.0 and 2.0
•	Parallel Port (IEEE 1284)
•	IRDA (infrared port)
•	IEEE 1, 1394
•	Serial Port
•	SCSI printing Port

Internet Printing is also supported for Windows 2000. Although the print port involves the client and server, we will discuss this topic based on the general situation, rather than comparing the local print port with the network print port.

In addition, some printer manufacturers choose to provide their own local or network printer port types.

 

Network Print port standard TCP/IP Port Monitor

For print devices connected to the network, the standard TCP/IP Port monitor is the best choice. Standard Port monitors enhance LPR (line printer remote, remote row printer) and LPR has been widely used as a true standard for network printing over the past few years. The standard port monitor is faster, more scalable, and bidirectional 1. In contrast, LPR is limited in all these aspects. Although Windows NT 4 and later versions provide registry modifications to help extend the lpr print 2 feature, these changes do not match the advantages of using standard port monitors.

The standard port monitor uses TCP/IP as the Transport Protocol, making it the preferred port monitor for Windows Server 2003. Standard Port monitors also use Simple Network Management Protocol (SNMP) to configure and monitor printer statuses.

The standard port monitor uses the raw or lpr print protocol to send documents to the printer. All in all, these protocols support most TCP/IP printers currently. Do not confuse these print protocols with transport protocols such as TCP/IP or data link protocol (DLC.

Raw is the default protocol for most printing devices. To send jobs in raw format, the Print Server opens a TCP stream for the printer network interface. For many devices, this interface will be port 9100. After creating a TCP/IP Port, Windows uses SNMP to query the object identifier (OID) of the device according to RFC 1759 (printer MIB ). If the device returns a value, parse the System File tcpmon. ini to find the matching item. If the printer manufacturer provides special configuration information for a specific device, the configuration information is created together with the configuration settings. For example, some external printing server interfaces support multiple printers (for example, Hewlett with three parallel port connections)
Packard jetdirect ex ). The manufacturer can use different ports to specify the printer to which a job should be submitted (for example, submit job 9102 to Port 1 and job 9103 to Port 2 ). This function is helpful for printing server interfaces that require special port names, suchPassPort.

You can configure a standard port monitor to bring it closer to the LPR standard (RFC 1179 ). In particular, you can useServer PropertiesOfPortTabConfigure portTo enable byte count. This setting may be helpful if the row printer Monitor (LPD) requires precise byte counts (which complies with RFC.

By default, the standard port monitor is inconsistent with the LPR standard in two aspects:

•

First, the standard port monitor does not comply with RFC 1179 requirements that the source TCP port should be located between port 721 and port 731. The standard port monitor uses the ports (ports 1024 and above) in the reserved general port pool ).

•

The LPR Standard specifies that the print job must contain information about the job size sent by the port monitor. To send a print job with job size information, the port monitor needs to perform a fake offline operation twice for the job, one for determining the job size, and the other for sending the job to the print daemon process. The printing performance can be improved only when the job is offline. Therefore, the standard port monitor sends messages directly to the offline program, but does not know the actual job size, and claims that the job has the default size, regardless of the actual size of the job.

The following table compares standard TCP/IP Port monitors with LPR port monitors.

LPR (compliant with RFC 1179)	Standard TCP/IP Port Monitor
Only 721731 Source Port	Source Port starting from the temporary port (9100 by default)
The timeout time for each port is 4 minutes and 3	No active port timeout
One-way single error status report	Use SNMP to provide rich status and error reports
The control file requires two off-line operations for exact Byte Count	By default, single file offline is enabled. (Configured through "port properties)
Print the target port 515	Print the target port 515 in LPR Mode

LPR

Although Windows Server 2003 uses standard TCP/IP Port monitors for network printers by default, to achieve interoperability with early systems and RFC-compliant LPR/lpd clients and devices, it still supports LPR/LPD printing.

The LPR utility allows applications on a computer to print background programs on a remote computer. The receiving component is called the row printer Monitor (LPD ). The LPR/lpd combination is developed for Unix computers, but is widely used in many other operating systems. Both utilities are included in the Unix "Print Service.

Default data type

The Unix print service sets the print data type when sending documents to the background print program. This data type is derived from the control commands included in the print job on the LPR client. It may be necessary to change the default data type on the client to avoid processing the PCL or postscript print job in raw format as text.

If the control command isFOrPThe data type is text, and the background print program will edit the document file to print it correctly. If the command isLThe data type is raw, and the background printer does not edit the document. If the command isOThe document has been formatted as postscript code and specified as raw data type.

Some UNIX systems generally send messages by default.FCommand to display the following symptoms:

•	The output data includes the PCL or postscript code.
•	Print out invalid extension characters.
•	Use the default font of the printer.
•	Print out unnecessary pages at the end.

You can use a registry key to force Windows 2000 to process data in raw format. For more information, see the following Knowledge Base Article:

•	"150930: LPD server plug-in and print control code"
•	"168457: Configure an independent printer to correctly handle LPR jobs"
•	"243729: prevents background print programs from performing character conversion from Cr or LF to Cr/LF"

LPR must include a precise byte count in the control file, but it cannot be obtained from the local print provider. After lprmon receives a document from the local print provider, the file will be taken offline again as a temporary file in the System32 subfolder to check the file size, then, the file size information is sent to the LPD printing server. The standard TCP/IP Port monitor does not comply with this RFC requirement, but sends a very large byte count to LPD to start printing. After the job is completed, it will close the connection directly. This step reduces the time and I/O by eliminating the creation of temporary offline files.

The LPR protocol does not return detailed error status reports. If a problem occurs, the returned message is always displayed as error, while windows reports "Printer error )". As discussed above, standard TCP/IP Ports provide more detailed error reports by using SNMP and standard printer MIB (RFC 1759.

Currently, almost all printer models are compatible with standard TCP/IP Port monitors. In most cases, the Unix print service (LPR/lpd) is required only for interoperability with other computer systems that strictly comply with the LPR/lpd RFC (1179) requirements ). Some LPD servers only require the exact Byte Count specified in RFC. For these systems, you only need to useEnable LPR Byte CountTo eliminate any errors. To improve performance and provide status monitoring, Microsoft recommends that you use standard TCP/IP ports whenever possible.

Appletalk

For the appletalk protocol, you can select an optional Windows component.Macintosh printing serverInstall it. The "Macintosh printing server" is selected in the control panelAdd/delete programs,Add/delete Windows Components,Other network file and printing servicesAnd then clickDetails. This option allows the server to receive jobs from the Macintosh client and print the jobs for devices using the appletalk protocol.

When creating an appletalk printer port, the system will prompt youCapturePort. If you capture the appletalk printing device, the latter will only receive print jobs from this printing server. This option may be helpful for providing more device management and control. To achieve higher level of interoperability, or in a hybrid environment of multiple servers or clients that print the device, you should not capture the port to support job-based connections.

In addition, when the "Macintosh printing service" is installed, the Macintosh client can connect to the printer sharing on the Windows Printing server. These printers can be locally connected to the server or through any network port, such as standard port monitors and LPR.

 

Local printer port USB Printing

Windows Server 2003 supports printing a Universal Serial Bus (USB) printer. USB consists of an external bus architecture and a communication protocol. The former is used to connect peripheral devices supporting USB to the master computer, the latter is used to support serial data transmission between the host system and peripherals supporting USB.

Parallel Port

Concurrent port printing is supported in Windows XP and Windows Server 2003. Traditionally, parallel port devices do not benefit from the introduction of the plug-and-play feature a few years ago. Windows XP and Windows Server 2003 perform regular round robin on parallel ports to provide a similar but not identical experience as plug-and-play. USB and ieee1394 fully support the "out-of-the-box" function and should be used in any situations where the printing performance and system performance are important. Parallel printing is slow and consumes more CPU overhead than other printing options.

IRDA (infrared port)

The infrared data transmission standard (IRDA) is a mechanism for information exchange between computers using infrared transmission without cable connections. IRDA can be performed between any two devices (such as computers and printers) that support IRDA. Windows 2003 supports IrDA printing.

IRDA is a Point-to-Point Protocol Based on TCP/IP and Winsock APIs (application programming interfaces. Generally, the IrDA printer supports out-of-the-box use. If the corresponding driver is available on the workstation, the driver is automatically installed. You can also selectAvailable PortThe following IrDA port uses the "Add Printer wizard ".

Connection speed:

Technology	Form of change	Speed
Parallelism (1284)	(Centronics)	250 kbps
	ECP/EPP	35 Mbps
IRDA		4 Mbps
Firewire (1394)	(Up to 63 devices)	400 Mbps
USB	1.0	12 Mbps
	2.0	480 Mbps
Bluetooth)		23 Mbps

IEEE 1, 1394

Windows Server 2003 supports the IEEE 1394 bus. The IEEE 1394 bus is designed for high-bandwidth devices, such as digital cameras, digital cameras, digital VCR, and storage devices. IEEE 1394 is a serial protocol that supports speed from 100 to 400 Mbps (depending on the implementation ). It provides an out-of-the-box high-speed bus that eliminates the need for peripherals to provide their own power, and provides support for synchronous data transmission.

You can connect up to 63 devices to an IEEE 1394 bus and connect up to 1,023 buses to form an ultra-large network with more than 64,000 devices. Each device can have up to 256 TB of memory that can be addressed through the bus. The internal mechanism ensures that all devices have the same access permissions to the bus.

Because IEEE 1394 can process very high data transmission rates, it is ideal for scanning or printing large-scale high-resolution data.

 

Internet print protocol (IPP)

Windows 2000 introduces support for the Internet print protocol (IPP) 1.0 specification. Windows Server 2003 continues to support the 1.0 standard. IPP contains two main components:

•	Web-based printer Management
•	Internet Printing

Web-based printer Management

Web-based printer management is very easy to use. The only premise is to install and run Internet Information Server (IIS) on the print server ). IIS is included in Windows 2000 Server by default and can be installed as an optional component on Windows 2000 Professional. On Windows Server 2003, you can use the "IIS lock" Wizard for web-based printer management and selectEnable Active Server PagesAndEnable Internet PrintingCheck box to configure. When a printer is created and shared, it can be managed through an Internet browser. To access web-based features, you can use the following URL:

Http ://Printserver/Printers

ReplacePrintserver. You must have sufficient permissions to pause the printer, clear jobs, and so on. Most Windows clients today use internal support for IPP, or the ability to download IPP support (http://www.microsoft.com) from Microsoft Web sites ). When IPP support is installed on the client, you can view and connect to the printer in a web browser. Microsoft strongly recommends this technology, especially for companies that want to deploy web-based solutions for finding and connecting printers.

Note:Windows XP provides Web-based management support for locally hosted printers by default. In the future, this option may be disabled by default (in Windows Server 2003 ), it can also be enabled through a process similar to the "IIS lock wizard" used in Windows Server 2003 series.

Internet Printing

When you connect to a printer through web-based printer management, one of the following two things will happen: Windows will create an IPP printer connection using the http port, or create a true-connect printer connection.

Establish an HTTP printer connection through a Web browser

If the security settings of the client Internet Explorer on the print server are set to "medium" or "high", Windows will create an IPP printer connection using the http port. Because this technology requires the installation of a local printer team column (unlike the true "Click-to-call" connection using RPC), the client must addLoad and uninstall driversPrivilegedAdministratorOrAdvanced UserPermission. (In Windows 2000, if the client only has "Advanced User Permissions", the connection is also valid .)

This solution is only recommended for untrusted specific Internet sites. The browser security settings for viewing these sites must be set to medium or higher. This type of printing is ideal for printing data at a location on a page to another location that does not share the same security and network infrastructure. However, in Windows Printing environments, HTTP printer connections are more restrictive than RPC connections (as described below) because they do not support Enhanced Metafile (EMF) features.

How to Establish an RPC printer connection through a Web browser

If the Internet Explorer setting of the client is set to "medium-low" or lower, selectConnectionWindows automatically creates an RPC to connect to the printer. True-connect or UNC connections have many advantages over IPP printer connections and should be used for Intranet printing (Local to company printing). In such an environment, the security settings in Internet Explorer can be set to "medium-low" or lower. True-connect connection is supported through the remote background Printing Program of windows. In the future, most innovations of Microsoft Softs will be aimed at RPC printer connections, instead
IPP printer connection.

For more information about RPC connections, see "click-and-click technical overview" on the following web address: http://www.microsoft.com/windowsserver2003/technologies/fileandprint/print/default.mspx.

 

Conclusion

Use the standard TCP/IP printer port and connect to the printer using Windows 2000 or later clients through rpc on TCP/IP. (Named Pipe implementation)

Using portconv. vbs script or print migrator 3.0 (or later), you can easily convert an existing LPR port to a standard TCP/IP Port.

Microsoft is evaluating support for standard TCP/IP ports for SNMP through the standard printer MIB (Management Information Base, management information library. In future versions, this implementation may be extended to include more status and error reports. The combination of new technologies such as generic plug-and-play (UPnP) and printer driver enhancements will bring device installation and management in the future enterprise print environment into a new era.

 

From: http://hi.baidu.com/tonywhj/blog/item/00b324fa657cf81f6c22eb15.html