311 lines
5.3 KiB
HTML
311 lines
5.3 KiB
HTML
<HTML
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><HEAD
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><TITLE
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>Xerox, Novell, and History</TITLE
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.57"><LINK
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TITLE="Linux Network Administrators Guide"
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HREF="index.html"><LINK
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TITLE="IPX and the NCP Filesystem"
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TITLE="IPX and the NCP Filesystem"
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>Linux Network Administrators Guide</TH
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WIDTH="10%"
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><TD
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WIDTH="80%"
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>Chapter 15. IPX and the NCP Filesystem</TD
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><TD
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WIDTH="10%"
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><DIV
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CLASS="SECT1"
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><H1
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CLASS="SECT1"
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><A
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NAME="AEN11684"
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>15.1. Xerox, Novell, and History</A
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></H1
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><P
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>
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First, let's look at where the protocols came from and what they look
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like. In the late 1970s, the Xerox Corporation developed and
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published an open standard called the Xerox Network Specification
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(XNS). The Xerox Network Specification described a series of protocols
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designed for general purpose internetworking, with a strong emphasis
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on the use of local area networks. There were two primary networking
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protocols involved: the Internet Datagram Protocol (IDP), which
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provided a connectionless and unreliable transport of datagrams from
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one host to another, and the Sequenced Packet Protocol (SPP), which
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was a modified form of IDP that was connection-based and reliable. The
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datagrams of an XNS network were individually addressed. The
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addressing scheme used a combination of a 4-byte IDP network
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address (which was uniquely assigned to each Ethernet LAN segment),
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and the 6-byte node address (the address of the NIC card). Routers
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were devices that switched datagrams between two or more separate IDP
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networks. IDP has no notion of subnetworks; any new collection of
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hosts requires another network address to be assigned. Network
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addresses are chosen such that they are unique on the internetwork in
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question. Sometimes administrators develop conventions by having each
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byte encode some other information, such as geographic location, so that
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network addresses are allocated in a systemic way; it isn't a
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protocol requirement, however.</P
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><P
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>
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The Novell Corporation chose to base their own networking suite on the
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XNS suite. Novell made small enhancements to IDP and SPP and renamed
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them IPX (Internet Packet eXchange) and SPX (Sequenced Packet
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eXchange). Novell added new protocols, such as the NetWare Core
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Protocol (NCP), which provided file and printer sharing features that
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ran over IPX, and the Service Advertisement Protocol (SAP), which
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enabled hosts on a Novell network to know which hosts provided which
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services.</P
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><P
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> <A
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HREF="x11684.html#X-087-2-IX.PROTOCOL.FAMILY"
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>Table 15-1</A
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> maps the relationship between
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the XNS, Novell, and TCP/IP suites in terms of function. The relationships
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are an approximation only, but should help you understand what is
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happening when we refer to these protocols later on.</P
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><DIV
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CLASS="TABLE"
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><A
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NAME="X-087-2-IX.PROTOCOL.FAMILY"
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></A
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><P
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><B
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>Table 15-1. XNS, Novell, and TCP/IP Protocol Relationships</B
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></P
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><TABLE
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BORDER="1"
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CLASS="CALSTABLE"
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><THEAD
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><TR
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><TH
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ALIGN="LEFT"
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VALIGN="TOP"
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>XNS</TH
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><TH
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ALIGN="LEFT"
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VALIGN="TOP"
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>Novell</TH
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><TH
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ALIGN="LEFT"
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VALIGN="TOP"
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>TCP/IP</TH
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><TH
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ALIGN="LEFT"
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VALIGN="TOP"
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>Features</TH
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></TR
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></THEAD
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><TBODY
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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>IDP</TD
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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>IPX</TD
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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>UDP/IP</TD
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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>Connectionless, unreliable transport</TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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>SPP</TD
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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>SPX</TD
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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>TCP</TD
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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>Connection-based, reliable transport</TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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><EFBFBD></TD
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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>NCP</TD
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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>NFS</TD
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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>File services</TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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><EFBFBD></TD
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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>RIP</TD
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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>RIP</TD
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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>Routing information exchange</TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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><EFBFBD></TD
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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>SAP</TD
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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><EFBFBD></TD
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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>Service availability information exchange</TD
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></TR
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></TBODY
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></TABLE
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></DIV
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></DIV
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><DIV
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CLASS="NAVFOOTER"
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WIDTH="100%"><TABLE
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WIDTH="100%"
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CELLPADDING="0"
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CELLSPACING="0"
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><TR
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><TD
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WIDTH="33%"
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ALIGN="left"
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VALIGN="top"
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><A
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HREF="x-087-2-ipx.html"
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>Prev</A
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WIDTH="34%"
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ALIGN="center"
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><A
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HREF="index.html"
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>Home</A
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>Next</A
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WIDTH="33%"
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>IPX and the NCP Filesystem</TD
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WIDTH="34%"
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ALIGN="center"
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VALIGN="top"
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HREF="x-087-2-ipx.html"
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>Up</A
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WIDTH="33%"
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ALIGN="right"
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VALIGN="top"
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>IPX and Linux</TD
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></TR
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> |