2.1.1 Network History
The history of computer networking is complex.
It has involved many people from all over the world over the past 35 years. Presented here is a simplified view of how the Internet evolved. The processes of invention and commercialization are far more complicated, but it is helpful to look at the fundamental development.
In the 1940s computers were large electromechanical devices that were prone to failure. In 1947 the invention of a semiconductor transistor opened up many possibilities for making smaller, more reliable computers. In the 1950s mainframe computers, which were run by punched card programs, began to be used by large institutions. In the late ...view middle of the document...
The drawback to this type of system was that there was very little direct communication and then only with those who knew about the bulletin board. Another limitation was that the bulletin board computer required one modem per connection. If five people connected simultaneously it would require five modems connected to five separate phone lines. As the number of people who wanted to use the system grew, the system was not able to handle the demand. For example, imagine if 500 people wanted to connect at the same time. Starting in the 1960s and continuing through the 70s, 80s, and 90s, the Department of Defense (DoD) developed large, reliable, wide-area networks (WANs) for military and scientific reasons. This technology was different from the point-to-point communication used in bulletin boards. It allowed multiple computers to be connected together using many different paths. The network itself would determine how to move data from one computer to another. Instead of only being able to communicate with one other computer at a time, many computers could be reached using the same connection. The DoDs WAN eventually became the Internet.
2.1.3 Networking Devices
Equipment that connects directly to a network segment is referred to as a device. These devices are broken up into two classifications. The first classification is end-user devices. End-user devices include computers, printers, scanners, and other devices that provide services directly to the user. The second classification is network devices. Network devices include all the devices that connect the end-user devices together to allow them to communicate.
End-user devices that provide users with a connection to the network are also referred to as hosts.
These devices allow users to share, create, and obtain information. The host devices can exist without a network, but without the network the host capabilities are greatly reduced. Host devices are physically connected to the network media using a network interface card (NIC). They use this connection to perform the tasks of sending e-mails, printing reports, scanning pictures, or accessing databases.
A NIC is a printed circuit board that fits into the expansion slot of a bus on a computer motherboard, or it can be a peripheral device. It is also called a network adapter. Laptop or notebook computer NICs are usually the size of a PCMCIA card.
Each individual NIC carries a unique code, called a Media Access Control (MAC) address. This address is used to control data communication for the host on the network. More about the MAC address will be covered later. As the name implies, the NIC controls host access to the medium.
There are no standardized symbols for end-user devices in the networking industry.
They appear similar to the real devices to allow for quick recognition.
Network devices provide extension of cable connections, concentration of connections, conversion of data formats, and management...