mirror of https://github.com/tLDP/LDP
193 lines
5.7 KiB
XML
193 lines
5.7 KiB
XML
<sect1 id="PLIP">
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<title>PLIP</title>
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<para>
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PLIP (Parallel Line IP), is like SLIP, in that it is used for
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providing a point to point network connection between two machines,
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except that it is designed to use the parallel printer ports on your
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machine instead of the serial ports (a cabling diagram in included in
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the cabling diagram section later in this document). Because it is
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possible to transfer more than one bit at a time with a parallel port,
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it is possible to attain higher speeds with the plip interface than
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with a standard serial device. In addition, even the simplest of
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parallel ports, printer ports, can be used in lieu of you having to
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purchase comparatively expensive 16550AFN UART's for your serial
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ports. PLIP uses a lot of CPU compared to a serial link and is most
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certainly not a good option if you can obtain some cheap ethernet
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cards, but it will work when nothing else is available and will work
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quite well. You should expect a data transfer rate of about 20
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kilobytes per second when a link is running well.
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</para>
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7.2. PLIP for Linux-2.0
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<para>
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PLIP device names are `plip0', `plip1 and plip2.
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</para>
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<para>
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<screen>
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Kernel Compile Options:
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Network device support --->
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<*> PLIP (parallel port) support
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</screen>
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</para>
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<para>
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The PLIP device drivers competes with the parallel device driver for
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the parallel port hardware. If you wish to use both drivers then you
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should compile them both as modules to ensure that you are able to
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select which port you want to use for PLIP and which ports you want
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for the printer driver. Refer to the ``Modules mini-HOWTO'' for more
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information on kernel module configuration.
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</para>
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<para>
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Please note that some laptops use chipsets that will not work with
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PLIP because they do not allow some combinations of signals that PLIP
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relies on, that printers don't use.
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</para>
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<para>
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The Linux plip interface is compatible with the Crynwyr Packet Driver
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PLIP and this will mean that you can connect your Linux machine to a
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DOS machine running any other sort of tcp/ip software via plip.
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</para>
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<para>
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In the 2.0.* series kernel the plip devices are mapped to i/o port and
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IRQ as follows:
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</para>
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<para>
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<screen>
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device i/o IRQ
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------ ----- ---
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plip0 0x3bc 5
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plip1 0x378 7
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plip2 0x278 2
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</screen>
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</para>
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<para>
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If your parallel ports don't match any of the above combinations then
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you can change the IRQ of a port using the ifconfig command using the
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`irq' parameter (be sure to enable IRQ's on your printer ports in your
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ROM BIOS if it supports this option). As an alternative, you can
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specify ``io='' annd ``irq='' options on the insmod command line, if
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you use modules. For example:
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</para>
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<para>
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<screen>
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root# insmod plip.o io=0x288 irq=5
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</screen>
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</para>
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<para>
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PLIP operation is controlled by two timeouts, whose default values are
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probably ok in most cases. You will probably need to increase them if
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you have an especially slow computer, in which case the timers to
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increase are actually on the other computer. A program called
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plipconfig exists that allows you to change these timer settings
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without recompiling your kernel. It is supplied with many Linux
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distributions.
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</para>
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<para>
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To configure a plip interface, you will need to invoke the following
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commands (or add them to your initialization scripts):
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</para>
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<para>
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<screen>
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root# /sbin/ifconfig plip1 localplip pointopoint remoteplip
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root# /sbin/route add remoteplip plip1
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</screen>
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</para>
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<para>
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Here, the port being used is the one at I/O address 0x378; localplip
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amd remoteplip are the names or IP addresses used over the PLIP cable.
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I personally keep them in my /etc/hosts database:
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</para>
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<para>
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<screen>
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# plip entries
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192.168.3.1 localplip
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192.168.3.2 remoteplip
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</screen>
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</para>
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<para>
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The pointopoint parameter has the same meaning as for SLIP, in that it
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specifies the address of the machine at the other end of the link.
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</para>
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<para>
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In almost all respects you can treat a plip interface as though it
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were a SLIP interface, except that neither dip nor slattach need be,
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nor can be, used.
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</para>
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<para>
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Further information on PLIP may be obtained from the ``PLIP mini-
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HOWTO''.
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</para>
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7.3. PLIP for Linux-2.2
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<para>
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During development of the 2.1 kernel versions, support for the
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parallel port was changed to a better setup.
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</para>
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<para>
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<screen>
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Kernel Compile Options:
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General setup --->
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[*] Parallel port support
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Network device support --->
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<*> PLIP (parallel port) support
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</screen>
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</para>
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<para>
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The new code for PLIP behaves like the old one (use the same ifconfig
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and route commands as in the previous section, but initialization of
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the device is different due to the advanced parallel port support.
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</para>
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<para>
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The ``first'' PLIP device is always called ``plip0'', where first is
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the first device detected by the system, similarly to what happens for
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Ethernet devices. The actual parallel port being used is one of the
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available ports, as shown in /proc/parport. For example, if you have
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only one parallel port, you'll only have a directory called
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/proc/parport/0.
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</para>
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<para>
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If your kernel didn't detect the IRQ number used by your port,
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``insmod plip'' will fail; in this case just write the right number to
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/proc/parport/0/irq and reinvoke insmod.
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</para>
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<para>
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Complete information about parallel port management is available in
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the file Documentation/parport.txt, part of your kernel sources.
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</para>
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<EFBFBD> PLIP information can be found in The Network Administrator Guide
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<http://metalab.unc.edu/mdw/LDP/nag/nag.html>
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PLIP allows the cheap connection of two machines.
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It uses a parallel port and a special cable, achieving speeds of
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10kBps to 20kBps.
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</sect1>
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