Connecting
Personal Computers To The Enterprise Internetwork
A
Hummingbird Communications Ltd. White Paper
Copyright ©1995 Hummingbird Communications Ltd.
Table
Contents
Network
Computing, the computing paradigm of the 1990's,
has demanded technologies that deliver the
computing power and information of the enterprise
internetwork to the PC desktop. These
technologies are rapidly evolving to provide the
PC with a seamless interface to the internetwork,
and the growing global area network (GAN)- called
the World Wide Web. Although legacy technologies
such as terminal emulation, and the classic
Novell PC-LAN client server model, have served us
well, today they offer limited connectivity,
interoperability and overall functionality.
During the 1980's, TCP/IP network transport
software, the Network File System (NFS), and the
X Window System emerged as new enabling
technologies in the UNIX network environment.
TCP/IP, NFS and X Windows have gained widespread
acceptance in the rapidly expanding PC enterprise
connectivity market, and have radically changed
the concept of PC desktop internetwork
connectivity, and enterprise-wide distribution of
information and computing resources.
Today,
information system managers are confronted with a
jungle of PC to internetwork connectivity
products all claiming higher performance,
reliability, interoperability, and to be the best
"open system implementation." The focus
of this white paper is to present a general
overview of PC to enterprise connectivity, define
the components of a PC to internetwork
connectivity product, and examine new and
existing enabling technologies based on open
standards. PC to internetwork connectivity will
be addressed from the perspective of the PC
user's requirements, and the organizational
benefits and issues of integrating PCs with the
enterprise internetwork.
In
today's global economy the distribution of
computing resources and information is paramount
to organizational competitiveness. The ability to
effectively distribute information and leverage
computing resources throughout the organization
is a major force driving PC to enterprise
internetwork integration. Networked PCs empower
the workforce and increase productivity by
bringing information to the desktop. The physical
location of applications, information and
computing resources becomes irrelevant in
internetwork computing environments, as
applications both remote and local, are
seamlessly integrated into the PC users desktop.
Organizational investment in PC hardware and
software mandates the PC's integration within the
internetwork computing environment. In 1994, an
estimated 40 million personal computers were
purchased worldwide, International Data
Corporation (IDC) forecasts that an additional 57
million will be sold in 1995, and more than 70
million will be sold in 1996. The personal
computer is the desktop of the present and
future. Personal computers have metamorphosed
into personal workstations delivering enormous
computing power and functionality to the desktop.
Organizational
Benefits of PC to Enterprise Internetwork
Connectivity
Amortizes investment in PC
hardware and software.
Leverages PC user's
experience with PC software.
Integrates PC desktops into
the organization's information
infrastructure.
Leverages investment in
internetwork based hardware and software.
Enables network based
applications to be distributed throughout
the enterprise.
Integrates heterogeneous PC
environments- Windows-NT-OS/2-Macintosh.
Integrates heterogeneous
Mainframe-Midrange and Minicomputer
environments.
The
enterprise internetwork of the 1990's typically
consists of multivendor computer environments
often requiring more sophisticated and highly
functional connectivity technologies than existed
during the 1980's. During the 1980's, PC users
connected to hosts via serial lines or modems, or
by running terminal emulation software on the PC
- making the PC appear as a terminal. Terminal
emulation software enabled the PC user to view
host applications in character mode, and provided
the ability to copy files to and from the host.
Today's PC to enterprise connectivity products
integrate a suite of connectivity technologies,
providing more than simplistic terminal emulation
to proprietary hosts. Their rapidly evolving
feature sets and application suites are
responding to the increasingly sophisticated
needs of PC users in multivendor internetwork
computing environments. The graphic below depicts
common types of communication technologies used
in multivendor computing environments.
Although
thousands of PC users still connect to character
based applications with terminal emulation
software, and access print and file services with
proprietary protocols, the new generation of PC
to internetwork connectivity products are built
on open standards integrating TCP/IP, NFS and X
Windows. Since Microsoft's endorsement of TCP/IP,
and subsequent integration with Windows NT and
Windows 95 operating systems, these open standard
technologies have rapidly gained widespread
acceptance as key interoperability solutions for
integrating the personal computer and the
enterprise internetwork.
At
the core of PC internetwork connectivity products
is TCP/IP network transport software: a feature
rich routable protocol suite that provides
interoperability between disparate computer
systems. TCP/IP paves an " application
highway" for many enterprise internetwork
applications to run over, including NFS, PC X
servers and Internet browsers. The following
table depicts a generic PC to enterprise
internetwork connectivity suite.
Emerging
in the early 1980's, Ethernet and the TCP/IP
protocol suite represented major technological
advances in the evolution of PC to UNIX
connectivity. Ethernet significantly increased
the bandwidth, speed, and functionality of
networks from snail like 2400-9600 baud of serial
lines, to a warp speed of 10 Mbps and now 100
Mbps with fast Ethernet and switching. Although a
variety of other options (proprietary protocols)
exist for connecting the PC to the enterprise
internetwork , TCP/IP has rapidly become a
defacto standard for more than PC-UNIX
connectivity. The TCP/IP protocol is scaleable,
provides transparent internetwork connectivity,
and integrates NFS as a common element. TCP/IP is
actually a lower level specification of the
Internet protocol suite which includes
specifications for common Internet applications
such as electronic mail, terminal emulation and
NFS file and print services.
Original
Source: Stacks Malamud, 1992
TCP/IP
is the protocol that can take the PC user
virtually anywhere - across the hall to an NFS
file server - or to a Web server on another
continent. TCP/IP implementations for the
personal computer have undergone a significant
evolution over the last five years, and are now
shamelessly integrated into personal computer
operating environments. Many TCP/IP products
support both NDIS and ODI Ethernet standards and
can coexist with other protocol stacks such as
NetWare IPX/SPX, LAN Manager, Windows for
Workgroups and Banyan Vines.
Along
with NFS, TCP/IP is usually integrated with UNIX
operating systems, however, Microsoft has
recently integrated TCP/IP with the Windows NT
operating system, and is expected to do the same
with Windows 95. The 32-bit processing and
virtual memory of Windows NT (no longer
constrained by 640 K of the DOS/Windows
environment) offers a tremendous advantage over
16-bit DOS/Windows implementations. The advantage
of integrated TCP/IP is not only in convenience
and cost saving, but more importantly in
performance, and the ability to multitask
applications. Some Windows NT users exploit the
improved memory management of Windows NT, by
employing four or five different protocol stacks
for connectivity to the enterprise computing
network.
Microsoft
Windows 3.1 users, however, must rely on TCP/IP
implementations from third party developers, and
are also constrained by the memory boundaries
inherent in the DOS operating system. The
following table depicts the most common TCP/IP
implementations currently available for Windows
3.1 based personal computers
TCP/IP
Implementations For Microsoft Windows 3.1
Implementation
Advantage/Disadvantage
Terminate
Stay Resident (TSR) Conventional RAM used
MS-Windows Dynamic Link Libraries (DLL) Minimal
conventional RAM used
MS-Windows (VxD) No RAM used
A
compelling argument exists for each TCP/IP
implementation, and they have their own strengths
and weakness, which may impact performance,
memory, and functionality. Depending on your
specific PC and/or network configuration it may
be necessary to run several protocol stacks on
your PC; for example TCP/IP and IPX/SPX. In this
case many networked PC users use DLL or VxD
TCP/IP implementations to conserve conventional
memory and avoid RAM-CRAM.
The
Windows Sockets Application Programming Interface
(WinSock API) is recognized as an open standard
specification for the development of Microsoft
Windows, Windows NT and Windows 95 TCP/IP
applications. The leading vendors of TCP/IP
participated in the development of WinSock and it
has become a component of the Windows Open
Services Architecture API suite. The objective of
WinSock is to provide a single transport level
API for application developers, and a standard
interface that all TCP/IP suppliers can support.
A major advantage of WinSock for PC users is that
TCP/IP applications (PC X servers, NFS, terminal
emulators, etc.) that are compliant with the API
will be able to run over any WinSock compliant
TCP/IP. WinSock supports TCP/IP, IPX/SPX,
AppleTalk, DECnet and OSI, and provides a
framework for other transports to be added. A new
specification includes an API that supports
multimedia over ATM and ISDN.
The
OSI Model - TCP/IP and WinSock API
Perhaps
one of the most important software products to
emerge from the Ethernet-TCP/IP-UNIX environment
is the Network File System, which has become a
defacto standard for distributed print and file
services. NFS was designed as a true
client/server distributed file system that
provides transparent file access between
heterogeneous computers. A major advantage of NFS
is its ability to transparently mount and access
file systems, making the UNIX, NT or PC file
system appear to the PC user as if it were a
local drive.
NFS
is usually supplied as an extension of the
operating system, along with TCP/IP on UNIX
computers. As with Windows 3.1 based TCP/IP
(until Windows 95, and currently Windows NT), NFS
client and/or server implementations must be
added to the PC. In addition to providing print
and file services to the PC, some NFS
implementations can provide peer-to-peer LAN
networking, by enabling the PC to be configured
as an NFS client and server. This allows other
PCs and workstations to mount the server PC drive
and access file systems in the same way as
Microsoft's Windows for Workgroups, enabling file
sharing between PCs, rather than through a UNIX
server.
The X Window System
The X
Window System is an open network
software-windowing technology that enables many
different types of computing platforms to share
information and applications interoperably. X has
revolutionized PC to enterprise internetwork
connectivity by allowing the PC user to connect
to, and display applications from heterogeneous
computers. X has rapidly become a defacto
standard in network computing environments, and
is the accepted windowing system for all UNIX
systems employed on workstations, minicomputers,
mainframes and supercomputers. X is currently in
the process of migrating to the Windows NT
platform, as various UNIX application developers
are currently in the process of porting UNIX/X
Windows applications to NT servers and
workstations.
Contrasting
Legacy Terminal Emulation And X
Traditional
access to network based applications via terminal
emulation has limited the PC's access to
character mode emulation and connection to a
single or specific host platform. New PC
internetwork connectivity software products
integrate X within the PC environment (DOS,
Windows, Windows NT, Windows 95 and OS/2) and are
an integral component of internetwork
connectivity products. PC X Windows software
implementations are termed PC X servers, and
enable PC users to access applications from many
different computer systems anywhere on the
network. PC X server software has become one of
the most powerful PC - enterprise internetwork
connectivity technologies available today. They
are similar to PC terminal emulators only in the
sense that they both establish a connection to
networked computers. PC X servers utilize the X
Window System's graphics capability, which
enables the distribution of graphical user
interfaces, applications, and bitmapped images
across the network.
PC X
servers utilize the power of X to connect to
UNIX, VMS, Ultrix, and OSF/1 hosts over TCP/IP.
All variants of UNIX and VMS operating systems
incorporate X as their standard graphical
windowing system, and X provides a common bond
facilitating enterprise-wide computer
interoperability between these systems.
Provide a single software
technology for interoperable
PC-internetwork connectivity
Allow the PC user to
establish simultaneous connections to
many different computers
Display graphical
applications and user interfaces in
windows on the PC
Cut and paste information
(text and graphics) between different
computing systems
Access powerful applications
and information running on networked
computers from PC
Allow organizations to
leverage their investment in personal
computers
Preserves the user's
relationship and experience with the PC
Work within the PC
environment: Windows, Windows NT, Windows
95, and OS/2
The
primary function of PC-Internetwork connectivity
products is to make host and internetwork
resources available to the user. However,
internetwork resources now encompass LANs, WANs,
and a burgeoning Global Area Network. PC
internetwork product differentiation is occurring
at a rapid pace, most notably in the level of
product complexity, host connectivity support, PC
platforms supported, and Internet protocols
supported.
While
the path to PC - internetwork connectivity
continues to be one of evolution, new products
are emerging that encompass nearly the entire
Internet protocol suite. These new products,
often coined connectivity suites, provide higher
levels of integration within the PC's operating
environment - Windows, Windows NT, Windows 95 and
OS/2. The PC connectivity suite's functionality
extends well beyond simplistic file and print
services. In a seemingly never ending quest for
differentiation, many PC connectivity suites are
taking on a Kmart look and feel, as more and more
Internet protocols (applications) are added to
the mix. Is more better? Or is seamless
integration of core best of breed applications
better?
In
defining the PC Internet connectivity product we
established that TCP/IP was a core application
functioning primarily as the network transport.
Depending on the needs of the organization, and
the PC user, some connectivity technologies may
be of greater or lessor importance. Beyond
simplistic print and file services, and
electronic mail, emulation technologies, such as
TN3270 or X Windows usually are a requirement for
many PC users. They provide access to mission
critical applications and data bases often
residing on mainframes and UNIX midrange servers.
Therefore,
emulation technologies could also be considered
core applications for the average PC user.
Additional applications such as ping, DHCP and
TFTP and Internet browsers, may indeed be of
lessor importance to the average user, than to a
network administrator, or technically oriented
users. In some cases more is not better.
Windows,
Windows NT and Windows 95 internetwork
connectivity applications provide a new level of
integration and connectivity beyond what was
offered by network operating systems and other
DOS applications that executed from a command
line. PC internetwork connectivity applications
now allow PC users to manage the complexity of
network computing within a familiar graphical
user environment. Icons represent TCP/IP stacks,
Internet browsers, electronic mail, and network
and local applications. File transfer and print
services are facilitated through drag and drop
procedures. The internetwork is now transparent
to the PC user. PC internetwork connectivity
products have become personal productivity tools.
As a personal productivity tool, the internetwork
connectivity product will be used much in the
same way word processors and spread sheets were
during the 1980's. There is no question they may
have as great an impact.
PC
internetwork connectivity products are rapidly
emerging to meet an extremely diverse set of
needs, many of which, however, are not universal.
In
conclusion, the core components of PC
internetwork products include: network transport
software (TCP/IP), legacy terminal emulation (DEC
VT and HP) , X Windows PC-UNIX integration (PC X
server), Internet tools (browsers HTML authoring
tools), IBM Services(TN3270), file and print
services (NFS, FTP, LPD) and email.
Factors To Consider When Selecting
PC Internetworking Products
1.)
Are the applications based on open system
technologies?
2.) Is the product easy to use, administer and
install?
3.) Are the
applications fully integrated within the PC's
environment, and do they run as native Windows,
Windows NT, Windows 95, OS/2 or Macintosh
applications?
4.) Will the performance of the product satisfy
PC users?
5.) What cost of ownership
issues are associated with the products?
6.) Does the vendor supply administrative tools?
7.) Can the product be installed on a network
file server and remotely configured, and can the
installation be automated?
8.) Does the product enable application
customization for your site and can components of
the software be removed and/or disabled?
9.) Are the applications considered "best of
breed" technology?
10.) Will all the applications you are paying for
be useful to everyday PC users?
11.) Does the product enable remote connectivity
for telecommuters and mobile employees?
12.) Finally, and also of great importance, did
the vendor develop the technology, or is the
application an OEM product?
- : -
The information in
this document represents the view of Hummingbird
Communications Ltd. on the topics discussed, as
of the publication’s date. The continually
changing market conditions and general dynamic
nature of the computer business mandates that
Hummingbird cannot guarantee the accuracy of any
information published after the date of
publication.
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