Table of Contents    Preface    Chapter 2    Netguru.net    Glossary

Chapter 1 - The Growth of Networking Technology

For those of us who have grown accustomed to seeing and utilizing various networks, it's hard to imagine what life would be like without them. The many conveniences that we enjoy, such as easy sharing of data and sharing of printers, would be hard to part with even for a day. Since the technology for linking personal computers together as well as with shared peripherals is not that old, many of us can remember the pains we had to go through to get a copy of a file to someone, especially if that someone was some distance away. Fortunately, those days are past.

Today networks link every part of the globe. As would be expected, they are primarily found in the developed nations, but new networks are popping up daily in developing nations. The influence of Hong Kong on Mainland China is spurring the growth of networking there as well as in surrounding Asian countries. The Middle East, especially Saudi Arabia and Israel, are investing in networks as well. Though Eastern European countries were technologically starved under Soviet control, many are now starting afresh, purchasing advanced technology, taking a sizable leap in the upgrade path. Gradually a global linking is taking place, and thousands more join in the benefits of networking daily.

Sharing data today is easier than ever, thanks to networking. Perhaps nothing else illustrates this better than the proliferation of electronic mail. E-mail has become one of the leading motivators for companies to invest in networks. As a means of sharing important information, E-mail is indispensable among organizations from every industry imaginable. A large number of us have become used to seeing a flashing icon or some other indicator signaling a letter waiting in our electronic mailboxes. The letter itself may contain notes about a friendly after-work game of golf, or last year's fiscal report. The ability to effortlessly and quickly move data from one person to the next is an option too good to pass up for many organizations.

Transmitting E-mail is one method of sharing data, but obviously there are others. Shared files may exist in one location with multiple people accessing them or updating parts of them. Database applications are found in virtually every computerized organization. Networks offer the capabilities of multi-user access. As you can imagine, there is inherent danger in two people accessing and altering the same file at the same time. What happens if two people update the same record at once? In times past this scenario would result in the "deadly embrace", where both parties became locked up and had to reboot, resulting in lost or corrupted data. More sophisticated database applications incorporate record locking, a means by which a person updating a record has exclusive use of the record while others who attempt to access it can not do so. This certainly eliminates the problems surrounding lock-ups but doesn't really eliminate the frustration of waiting on a record that someone else is updating, especially if that someone forgot what they were doing and headed off to lunch.

Novell attempts to add to database functionality by providing BTRIEVE. This package is NetWare's database manager and it allows the implementation of features like record locking in the NetWare environment.

Not only data files may be shared, but executable files may be shared as well. When a user invokes an executable file on a network server, a copy of it is transmitted over the network into the memory of the local user's workstation. That is where the actual execution takes place, not on the file server. The fact that execution takes place locally is what distinguishes PC networks from mainframe networks where processing is done centrally on the host and the terminals merely display the result. Once the executable file has been copied, it is then available for copying by other users. In this manner, a single executable file on a central file server can work for multiple users. Great care should be taken, however, to ensure that sufficient licensure has been secured in a multi-user environment so as to remain legal.

Figure 1-1: Modern networks can contain several components for allowing data and resource sharing.

One of the distinct benefits of modern networking is the ability to share peripherals. Few companies have the available resources to place a printer on every user's desk. Networks offer a logical and cost-effective solution. Since, once again, the introduction of several users could cause conflict at the printer, spooling is utilized so that print jobs can be arranged in an orderly manner. NetWare provides such services in the form of print queues and print servers.

The ability of sharing printers and disk space has been the driving force behind many companies installing PC-based networks. Networks are now found in nearly every type of industry there is. From small companies to large multi-national corporations, all benefit from sharing peripherals, including modems. Shared modems are typically called modem servers. Today's incarnations support multiple lines and are feature-laden.

Computers have been around for several decades now. Forty years ago when large organizations utilized them, they were neither inexpensive nor portable. It's interesting to watch television documentaries of the computer industry's growth, especially the old footage of gentlemen proudly standing next to a glittering behemoth, full of flashing lights and whirring tapes. Those same film clips usually show roomfuls of data entry personnel clicking away at card punch machines, a sight you are not likely to see today.

Figure 1-2: Early computer systems had no provisions for networking. Data was shared via punched card or tape.

The early computers were large in size due to the fact that vacuum tubes were used to facilitate their processing. It wasn't until the transistor was developed, and then the integrated circuit, that hardware began to assume a more compact size.

Memory in the early days of computing was extremely costly so machines had relatively little. The type of memory utilized was called "core memory" consisting of metal rings and rods that were bulky at best.

Storing data involved transferring it to tape, to punched cards, or later, to large hard disk systems. There were no floppy drives, and computers were not hooked together, so there was no easy way of sharing data without first placing it on tape or on punched card. As you can imagine, this placed a great deal of overhead on data sharing, and time truly became scarce as the computer became useful to more and more departments.

The first computers were not sophisticated enough to allow several users to utilize resources at once. Early operating systems were designed to process one job at a time. This type of processing was often called "batch" processing. Later, multitasking operating systems were de-veloped to allow several jobs to be processed simultaneously. Up to this point, computers were not "interactive". That is, they did not permit a user or operator to interact with the program while it was running.

As soon as the operating systems became multitasking, the next trend was to interactive systems. Operating systems had to be developed that could facilitate this. Once developed, multiple users could interact with the CPU simultaneously via a computer terminal. This alleviated the tremendous backlog of jobs waiting to be done in the single-user, single-task environment. Early connections for multiple users were the first fledgling steps for computer networking.

As systems grew, it became evident that the complete burden of processing rested on the CPU. It had to withstand access and processing for many users and had to oversee the routing of output to printers and terminals. Managing a CPU's resources effectively meant offloading mundane tasks that ate up CPU time. These tasks included communication processes. As the number of users interacting with a machine increased, the need for a device to take over this type of task became evident. When developed, the front-end processor experienced widespread usage. Front-end processors are still in use today, freeing up mainframe CPUs for more important tasks.

Once the attachment of several users to a mainframe at a local site had been mastered, the next task was to offer connections at remote sites. This was accomplished via telephone lines. Obviously connecting one user remotely didn't seem such a chore, but connecting multiple users via a single telephone line presented a greater challenge. Special devices were created to meet this need. Concentrators allowed the blending of signals at various rates from terminal devices. A controller could oversee the routing of these signals to the appropriate host. The combination of these two devices into a single device, called a cluster controller, allowed remote terminals to seamlessly interact with a host computer. This technology opened the door of computing to many organizations that couldn't afford to buy a mainframe of their own. Computer owners worked out time-sharing deals with less fortunate companies. In short, computer resource availability increased quite dramatically.

Figure 1-3: Remote access to computers via telephone lines greatly enhanced computer resource availability.

In the midst of these new advances, however, there was a major drawback. Purchasing a computer from a particular company locked you into the support provided by that company and it also locked you into using the particular communication technology employed by that company. If they shut down, so did your support. This problem was exacerbated by the poor interoperability among early computer vendors. As has always been the case, third-party companies sprang up to meet the interoperability needs, but significant differences in architecture and hardware implementation made their tasks difficult at best, sometimes impossible.

The major players on the block in early networking included the International Business Machines Corporation (IBM), which should be no surprise, and Digital Equipment Corporation (DEC). IBM's early networking followed a specification called SNA, or Systems Network Architecture. Several devices were developed using SNA allowing the combination of computer resources from several internal groups within a large organization. This feat was important because for the first time, companies could readily share data from one department with another as well as balance processing loads between computer resources. DEC's DECnet offered similar advantages.

The ability to balance processing load and resources was the prime motivator for launching us into the modern era of networking. There was one very large organization that discovered the necessity of spreading out the loads on its numerous computers. That organization was the United States Government. Spearheaded by the Department of Defense, a move to create a network linking the government's vast computer resources was undertaken. The end result brought together just about any group that might be in some way involved in defense and defense research, including many educational institutions. This expansive network was called ARPANET (Advanced Research Projects Agency Network).

What was so important about the development of ARPANET was the creation of protocols for linking dissimilar computers together. The evolution of these successes in interoperability led to the development of a very dominant set of protocols (called a suite) called TCP/IP protocols (Transmission Control Protocol / Internetwork Protocol). This unique group of specifications governs and facilitates the linking of computers practically all over the world. The huge internetwork that sprang from ARPANET is now called the Internet.

Development of networking on a more local level was also progressing, especially among developers of minicomputers. In the late 70s, DEC, Intel and Xerox developed a scheme for networking across multi-vendor platforms. This new type of localized network, called Ethernet, served these purposes well. Ethernet governs the physical aspects of interconnecting local computers such as the cabling type, allowable distances, how data is placed onto the wire, how the data is formatted, etc. Because of these characteristics, Ethernet is often referred to as a "media" protocol. Ethernet is still in use today, in the PC network era, offering speeds of data transfer up to 10 million bits per second (Mbps). Current Ethernet standards are governed by IEEE committee 802.

About the same time, a company called DataPoint developed a new protocol called ARCnet, short for Attached Resources Computer network. Like Ethernet, ARCnet is a set of media protocols. Interestingly enough, ARCnet is still marketed today at a price that is very budget oriented. It's speed, which is slow compared to other PC network protocols, is only 2.5 Mbps. This was based on the speed of early computer disk drive system speeds. ARCnet standards are governed by an informal group comprised of ARCnet-related vendors, not by IEEE. Yet, ARCnet is probably the most standardized network in terms of interoperability because of the strong commitment to interoperability amongst the vendors.

The ability to link computers, often those created by different vendors, is made feasible by the adoption of standards. Standards-setting organizations include the International Organization for Standardization (formerly the International Standards Organization or ISO) and the Institute of Electrical and Electronic Engineers (or IEEE). The contributions of these entities have pushed us into the next logical step of networking which is internetworking -- the linking of networks, which may differ significantly.

The technology of performing internetworking is still evolving as new feature-laden products are introduced almost daily. Realizing the benefits and importance of data and resource sharing, many companies are now connecting their networks from various departments or subsidiaries to each other, and implementing management tools that can govern the entire collection. These departments or other organizational units might be geographically located on opposite sides of the world or in the same building. Some may link with other companies on different continents creating a truly global network. The extension of networks across organizational, geographical and political boundaries will serve to bring our information, resources, and consequently our world, closer together.

Figure 1-4: Some enterprise networks or global networks span nearly the whole world.

From Novell's point of view, the movement toward global networking requires appropriate technology. The latest incarnation of NetWare reflects this line of thinking as it is specifically geared toward managing network resources beyond the confines of a single office, building or campus. NetWare 4.0 now allows a multiple file server environment to be administered with greater ease than with previous versions. Also many of the inner workings of the operating system itself has been shielded from the user.

The growth of modern networking will continue on its rapid curve for quite some time as technology continues to develop. Networks will continue to grow in both size and complexity. From their humble beginnings to the colossal systems of today, networks have evolved into an integral and necessary part of the corporate world.

Chapter 1 Study Tips

 

1. Be able to briefly identify the major developments in computer networking.

 

2. Know the beginning and development of the Internet and TCP/IP.

 

3. Know some of today's uses for computer networks.

 

4. Cite trends for future networking.

Table of Contents    Preface    Chapter 2    Netguru.net    Glossary

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