42 lines
1.8 KiB
HTML
42 lines
1.8 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 User Datagram Protocol</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="node15.html">More on Ports</A>
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<B>Up:</B> <A HREF="node7.html">TCP/IP Networks</A>
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<B> Previous:</B> <A HREF="node13.html">The Transmission Control Protocol</A>
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<BR> <P>
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<H2><A NAME="SECTION003370000">The User Datagram Protocol</A></H2>
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<A NAME="introtcpipudp"></A>
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Of course, TCP isn't the only user protocol in TCP/IP networking.
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Although suitable for applications like rlogin, the overhead
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involved is prohibitive for applications like NFS. Instead, it uses a
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sibling protocol of TCP called UDP, or <em>User Datagram Protocol</em>.
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Just like TCP, UDP also allows an application to contact a service on a
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certain port on the remote machine, but it doesn't establish a
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connection for this. Instead, you may use it to send single packets to
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the destination service-- hence its name.
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<P>
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Assume you have mounted the TeX directory hierarchy from the
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department's central NFS server, galois, and you want to view a
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document describing how to use LaTeX. You start your editor, who
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first reads in the entire file. However, it would take too long to
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establish a TCP connection with galois, send the file, and release
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it again. Instead, a request is made to galois, who sends the file
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in a couple of UDP packets, which is much faster. However, UDP was not
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made to deal with packet loss or corruption. It is up to the
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application-- NFS in this case-- to take care of this.
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<P>
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<HR>
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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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