65 lines
2.9 KiB
HTML
65 lines
2.9 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
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<HTML>
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<HEAD>
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<META NAME="GENERATOR" CONTENT="SGML-Tools 1.0.9">
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<TITLE>IP Sub-Networking Mini-Howto: Why subnetwork?</TITLE>
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<LINK HREF="IP-Subnetworking-6.html" REL=next>
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<LINK HREF="IP-Subnetworking-4.html" REL=previous>
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<LINK HREF="IP-Subnetworking.html#toc5" REL=contents>
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<A HREF="IP-Subnetworking-6.html">Next</A>
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<A HREF="IP-Subnetworking.html#toc5">Contents</A>
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<HR>
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<H2><A NAME="s5">5. Why subnetwork?</A></H2>
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<P>The reasons behind sub-networking date back to the early specification of
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IP - where just a few sites were running on Class A network numbers,
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which allow for millions of connected hosts.
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<P>
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<P>It is obviously a huge traffic and administration problem if all IP
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computers at a large site need to be connected to the same network:
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trying to manage such a huge beast would be a nightmare and the network
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would (almost certainly) collapse under the load of its own traffic
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(saturate).
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<P>
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<P>Enter sub-networking: the A class IP network address can be split up to
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allow its distribution across several (if not many) separate networks.
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The management of each separate network can easily be delegated as well.
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<P>
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<P>This allows small, manageable networks to be established - quite
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possibly using different networking technologies. Remember, you cannot mix
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Ethernet, Token Ring, FDDI, ATM etc on the same physical network - they
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can be interconnected, however!
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<P>
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<P>Other reasons for sub-networking are:-
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<UL>
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<LI>Physical site layout can create restrictions (cable run lengths)
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in terms of the how the physical infrastructure can be connected,
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requiring multiple networks. Sub-networking allows this to be done in an
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IP environment using a single IP network number.<BR><BR>
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This is in fact now very commonly done by ISPs who wish to give their
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permanently connected clients with local networks static IP numbers.
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</LI>
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<LI>Network traffic is sufficiently high to be causing significant
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slow downs. By splitting the network up using subnetworks, traffic that
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is local to a network segment can be kept local - reducing overall
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traffic and speeding up network connectivity without requiring more
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actual network bandwidth;</LI>
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<LI>Security requirements may well dictate that different classes of
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users do not share the same network - as traffic on a network can always
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be intercepted by a knowledgeable user. Sub-networking provides a way to
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keep the marketing department from snooping on the R & D network traffic
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(or students from snooping on the administration network)!</LI>
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<LI>You have equipment which uses incompatible networking technologies
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and need to interconnect them (as mentioned above).</LI>
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</UL>
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<P>
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<HR>
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<A HREF="IP-Subnetworking-6.html">Next</A>
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<A HREF="IP-Subnetworking-4.html">Previous</A>
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<A HREF="IP-Subnetworking.html#toc5">Contents</A>
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