As an alternative point of view, the network represents an essential component of modern technology infrastructure, offering the ability to interconnect computers, storage devices, computer peripherals, cellular telephones, personal digital assistants, video and audio devices, and, most importantly, other networks, to share resources and services, to share and exchange data and knowledge, and even to communicate and socialize.
A SIMPLE VIEW OF DATA COMMUNICATIONS
From the naivest perspective, it is usual to compare data communication by its comparison to the I/O methods that we have previously considered. In each case, the computer sends data to or receives data in the form of ‘‘messages’’ from another stratagem. For example, the ‘‘messages in the Little Man Computer were three-digit numbers that were ‘‘communicated’’ with the user using the effort and output baskets as a communiqué channel.
General Channel Characteristics
The communication frequency provides the pathway for the message between the two cooperating nodes in the model. Though the model in represents the channel as a straight point-to-point joining between the nodes, this is not normally the case. In realism, the channel can take numerous different procedures. In the simplest case, it strength be a direct joining between nodes in a local area network. More classically, the communication channel is actually divided into segments, called links.
NUMBER OF CONNECTIONS
Like buses, a communication channel can be point-to-point or multipoint, although the choice is often predetermined by the nature of the medium. Wireless networking, for example, is, of necessity, multipoint, because there is no realistic technological way to limit the number of radio signals in a given space. Conversely, fiber optics are usually point-to-point because of the difficulty of tapping into a fiber optic cable. Note that even a point-to-point channel can be shared by packets arriving at its input node from different sources.
Today, the most common end-node interface to a channel is a local area network connection, usually either wired or wireless Ethernet. Nonetheless, there are other possible interfaces to consider: Bluetooth, WiMax, DSL or cable link, various forms of cell phone technology, older types of network connections, and, to a more limited extent, telephone modem.