ch05.htm

this describes managing multivendor networks

<P>Sun's unique contributions to ONC are mainly in the upper application and service
layers (see Figure 5.1).</P>
<P>The lower layers of ONC are handled by TCP/IP running over Ethernet (or other
TCP/IP-compatible networks). The portions of TCP/IP that are relevant to understanding
ONC are as follows:

<UL>
	<LI><I>Transmission Control Protocol (TCP).</I> TCP delivers information between
	systems participating in the TCP/IP network. As part of this delivery process, TCP
	confirms receipt of the information and handles the retransmission of corrupted information.<BR>
	<BR>
	
	<LI><I>User Datagram Protocol (UDP).</I> UDP is a facility available for applications
	to deliver information between systems. Although similar to TCP, UDP does not provide
	the automatic error correction facilities of TCP and cannot verify receipt of data.
</UL>

<P><A HREF="javascript:if(confirm('http://docs.rinet.ru:8080/MuNet/ch05/05fig01.gif  \n\nThis file was not retrieved by Teleport Pro, because it was redirected to an invalid location.  You should report this problem to the site\'s webmaster.  \n\nDo you want to open it from the server?'))window.location='http://docs.rinet.ru:8080/MuNet/ch05/05fig01.gif'" tppabs="http://docs.rinet.ru:8080/MuNet/ch05/05fig01.gif"><B>FIG. 5.1</B></A> <I>Sun's ONC Architecture</I>

<UL>
	<LI><I>Internet Protocol (IP).</I> While TCP handles the delivery of data, IP determines
	the best possible route between two systems. This might or might not include moving
	the information between LANs or across WAN bridges.
</UL>

<P>TCP/IP is discussed in more detail in Chapter 9, &quot; PC LAN Network Operating
Systems&quot; (p. 198).</P>
<P>Sun's ONC services and functions lie on the standard TCP/IP layers as follows:

<UL>
	<LI><I>Remote Procedure Call (RPC).</I> RPC provides a common set of routines that
	programs can use to communicate with each other throughout the network. Whereas the
	TCP/IP UDP service facilitates the movement of information between two programs in
	the ONC environment, RPC adds structure and context on top of the delivery mechanism.
	From a broad perspective, RPC provides a common interface that two programs can use
	to converse with one another.<BR>
	<BR>
	
	<LI><I>External Data Representation (XDR).</I> XDR furnishes a common format for
	information moved through the ONC environment. Because different systems in a network
	might represent data in many different formats (for example, signed, packed decimal
	fields are invariably unique to each system), a common format that does not sacrifice
	efficiency for compatibility is necessary. XDR is a data description language that
	applications can use with RPC to enable two programs sharing information on the network
	to use a common format (even though the information might actually be stored on the
	two systems in different formats).<BR>
	<BR>
	
	<LI><I>Network File System (NFS).</I> In many respects, Sun is best known in the
	networking world for its implementation of NFS. NFS provides a networkwide file system
	that enables other systems supporting NFS to mount and access files (or sets of files).
</UL>

<P>As previously noted, Sun's approach to ONC has been to recruit other vendors and
manufacturers into the ONC fold, and NFS has been a key factor in the recruiting
process. For example, DEC, HP, and IBM have NFS implementations for many of their
proprietary operating systems. In the world of UNIX, NFS is frequently bundled with
TCP/IP to provide a LAN-wide file system. In fact, nearly 100 different companies
have implementations of NFS, XDR, and RPC for their particular systems or applications.</P>
<P>However, NFS, XDR and RPC are not the sole components of Sun's ONC environment.
Other members of this environment include the following:

<UL>
	<LI><I>Secure RPC.</I> An implementation of RPC with additional security that verifies
	the identity of each RPC user.<BR>
	<BR>
	
	<LI><I>RPC Generator (RPCGEN).</I> A high-level program development tool that simplifies
	RPC programming.<BR>
	<BR>
	
	<LI><I>RPC Application Program Interface (RPC API).</I> The combined library of the
	RPC and XDR interfaces made available for applications development on a given system.
	This is normally a high-level interface used by programmers.<BR>
	<BR>
	
	<LI><I>Automounter.</I> Works in conjunction with NFS to automatically mount and
	dismount files and file sets as they are needed.<BR>
	<BR>
	
	<LI><I>Network Information Services (NIS).</I> Maintains a common list (database)
	of files that can be accessed by various systems in the ONC environment. NIS implements
	a form of network security. Note that NIS was formerly known as Yellow Pages (YP).<BR>
	<BR>
	
	<LI><I>Network Lock Manager.</I> Provides record- and file-level locking of information
	accessed through NFS.<BR>
	<BR>
	
	<LI><I>Status Monitor.</I> Enables one system to determine whether another system
	has been restarted.<BR>
	<BR>
	
	<LI><I>Remote Execution (REX).</I> Enables a user on one system to execute commands
	and programs on other systems in the network.<BR>
	<BR>
	
	<LI><I>NETdisk.</I> Provides a booting mechanism for diskless workstations in the
	network.<BR>
	<BR>
	
	<LI><I>PC-NFS.</I> Provides services in support of PCs in the ONC environment. This
	topic will be discussed in more detail later in this chapter.
</UL>

<H3><A NAME="Heading4"></A><FONT COLOR="#000077">Application/User Relationship</FONT></H3>
<P>Because Solaris combines two UNIX implementations (AT&amp;T and Berkeley versions),
it uses the same multiuser, multitasking capabilities as these mainstream versions.</P>
<P>For the most part, Sun systems are used as engineering workstations. In this highly
graphical application, virtually every cycle of every available processor goes toward
maintaining the display and display quality (especially when manipulating 2-D and
3-D objects).</P>
<P>Sun also produces systems targeted as servers in large, multiuser environments,
and these models do not fall into the same general category of the engineering workstations.
Instead, they typically fall into one of two extremes:

<UL>
	<LI><I>No-user systems.</I> These systems are used solely as network devices (normally
	file servers). Although other users access these systems, they are doing so through
	their own native systems.<BR>
	<BR>
	
	<LI><I>Data center servers.</I> The high end of the server line includes large-capacity
	disk storage for local and networkwide use and support for a moderate number of terminals
	(up to 64). This size of device is, in fact, multiuser oriented and is similar in
	concept to the DEC VAX midrange systems.
</UL>

<P>The application's interaction with the user is somewhat at arm's length. The user
interacts with the operating system in a session, as with DEC's VMS and HP's MPE.
This session orientation gives the user a working area in which to function that
is (theoretically) independent from other users on the same system.</P>
<P>The application program, however, relies on system-level (or network-level) routines
to make the communications bridge between the user and itself. The information passing
across this bridge might be simple character-oriented data or complex graphics-oriented
information, depending on the application.</P>
<P>This approach to programming is common in the UNIX environment. In fact, in the
UNIX environment, much effort is made to isolate the program from the physical aspects
of the systems and the network. With Solaris and the ONC architecture, this same
philosophy is extended to encompass a much broader range of possibilities.
<H3><A NAME="Heading5"></A><FONT COLOR="#000077">Terminal Attachment Philosophy</FONT></H3>
<P>Where Sun's older architecture was based primarily on freestanding workstations,
Sun's new UltraComputing architecture is focused on the network. As Sun's products
became more accepted in a broader range of functions, Sun began to push into the
midrange computing market dominated by DEC, among others. In this market, the need
to provide a reasonable per-user cost dictated that Sun offer basic terminal connectivity
to the products they targeted toward this market. This terminal connectivity requirement
was in addition to a requirement for LAN connectivity.</P>
<P>To address this requirement, Sun provides simple, point-to-point connections between
terminals and its higher-end servers. The nature of this connection follows the approach
used by other UNIX implementations: a standard RS-232C connection to a variety of
character-oriented terminal devices (from a variety of manufacturers). Again, this
is similar to the approach used by other midrange computer manufacturers (such as
DEC and HP).</P>
<P>However, with the increased popularity in graphics-based user interfaces and X
Window terminals, Sun--and the rest of the industry--was forced to take a stand on
implementing a noncharacter terminal interface. Sun's response was to use a graphics-oriented
user interface it had co-developed with AT&amp;T for UNIX. This product was named
Open Look, and it worked with existing X Window terminal standards. In the interest
of establishing a common UNIX desktop, however, Sun agreed to forsake Open Look in
favor of Motif, as specified by the Common Desktop Environment (CDE).</P>
<P>One of Sun's earlier GUI innovations was its SunTools product, which enabled a
user to have more than a single terminal emulator on the screen at one time. SunTools
included two terminal emulators, the Terminal Tool, which was a true VT100 emulator,
and Command Tool, which recorded a history of the login session. SunTools later became
OpenWindows, although it still required two separate terminal emulators. Later, the
Open Software Foundation came up with the Motif interface--which Sun did not immediately
embrace, despite a tremendous user demand for the Windows-like GUI. Sun now sells
an implementation of CDE that runs on top of Solaris, which effectively put an end
to OpenWindows.</P>
<P>In terms of actually manufacturing any character or graphics-oriented terminals,
Sun has kept its distance. In fact, instead of embracing the X Terminal approach
as a manufacturer, Sun has introduced diskless workstations that offer the functions
of an X Terminal at a low price but with the advantages of an engineering workstation.</P>
<P>Sun unveiled this approach with the SPARCstation SLC, a SPARC-based workstation
that comes close to the price of X Terminal offerings but still provides the basic
functions of a workstation. Although the SLC is diskless, the ONC/NFS architecture
enables the SLC to retrieve programs and data from the network to which it is attached.
This is not altogether different from using diskless workstations in PC LANs.</P>
<P>Succeeding the SLC is the SPARC Xterminal 1, which boasts a clock speed of 50
MHz and runs the microSPARC processor. This X terminal offers strong performance,
and a high-resolution color display. Besides running X terminal applications, the
Xterminal 1 can run software that would otherwise require an additional system, such
as Windows or Macintosh. The Xterminal 1 includes standard X11R5 software, giving
it access to a variety of servers using TCP/IP, NFS, SNMP, BootP, Telnet, and several