86 lines
3.7 KiB
HTML
86 lines
3.7 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
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<!--Converted with LaTeX2HTML 96.1-c (Feb 29, 1996) by Nikos Drakos (nikos@cbl.leeds.ac.uk), CBLU, University of Leeds -->
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<HTML>
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<HEAD>
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<TITLE>The PLIP Interface</TITLE>
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</HEAD>
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<BODY LANG="EN">
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<A HREF="node1.html"><IMG WIDTH=65 HEIGHT=24 ALIGN=BOTTOM ALT="contents" SRC="contents_motif.gif"></A> <BR>
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<B> Next:</B> <A HREF="node71.html">The SLIP and PPP </A>
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<B>Up:</B> <A HREF="node65.html">Interface Configuration for IP</A>
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<B> Previous:</B> <A HREF="node69.html">Configuring a Gateway</A>
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<BR> <P>
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<H2><A NAME="SECTION007750000">The PLIP Interface</A></H2>
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When using a PLIP link to connect two machines, things are a
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little different from what you have to do when using an Ethernet.
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The former are so-called <em>point-to-point</em> links, because
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they involve only two hosts (``points''), as opposed
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to broadcast networks.
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<P>
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As an example, we consider the laptop computer of some employee at
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the Virtual Brewery that is connected to vlager via PLIP.
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The laptop itself is called vlite, and has only one
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parallel port. At boot time, this port will be registered as
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plip1. To activate the link, you have to configure the
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plip1 interface using the following commands:<A HREF="footnode.html#3180"><IMG ALIGN=BOTTOM ALT="gif" SRC="foot_motif.gif"></A>
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<Pre>
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# ifconfig plip1 vlite pointopoint vlager
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# route add default gw vlager
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</pre>
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The first command configures the interface, telling the kernel that this
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is a point-to-point link, with the remote side having the address of
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vlager. The second installs the default route, using
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vlager as gateway. On vlager, a similar ifconfig
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command is necessary to activate the link (a route invocation is
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not needed):
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<Pre>
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# ifconfig plip1 vlager pointopoint vlite
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</Pre>
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The interesting point is that the plip1 interface on
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vlager does not have to have a separate IP-address, but may also
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be given the address 191.72.1.1.<A HREF="footnode.html#2854"><IMG ALIGN=BOTTOM ALT="gif" SRC="foot_motif.gif"></A>
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<P>
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Now, we have configured routing from the laptop to the Brewery's
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network; what's still missing is a way to route from any of the
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Brewery's hosts to vlite. One particularly cumbersome way is
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to add a specific route to every host's routing table that names
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vlager as a gateway to vlite:
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<pre>
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# route add vlite gw vlager
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</Pre>
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<A NAME="2860"></A>
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<A NAME="2861"></A>
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<A NAME="3181"></A>
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<A NAME="2863"></A>
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<A NAME="2864"></A>
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A much better option when faced with temporary routes is to use dynamic
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routing. One way to do so is to use gated, a routing daemon,
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which you would have to install on each host in the network in order
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to distribute routing information dynamically. The easiest way,
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however, is to use <em>proxy</em> ARP. With proxy ARP, vlager will
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respond to any ARP query for vlite by sending its own Ethernet
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address. The effect of this is that all packets for vlite will wind
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up at vlager, which then forwards them to the laptop. We will come
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back to proxy ARP in section-<A HREF="#ifaceverifyarp"><IMG ALIGN=BOTTOM ALT="gif" SRC="cross_ref_motif.gif"></A> below.
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<P>
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Future Net-3 releases will contain a tool called plipconfig
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which will allow you to set the IRQ of the printer port to use. Later,
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this may even be replaced by a more general ifconfig command.
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<P>
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<HR><A HREF="node1.html"><IMG WIDTH=65 HEIGHT=24 ALIGN=BOTTOM ALT="contents" SRC="contents_motif.gif"></A> <BR>
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<B> Next:</B> <A HREF="node71.html">The SLIP and PPP </A>
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<B>Up:</B> <A HREF="node65.html">Interface Configuration for IP</A>
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<B> Previous:</B> <A HREF="node69.html">Configuring a Gateway</A>
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<P><ADDRESS>
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<I>Andrew Anderson <BR>
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Thu Mar 7 23:22:06 EST 1996</I>
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</ADDRESS>
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</BODY>
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</HTML>
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