Chapter 1: Questions 7, 14, and 17
How do local area networks (LANs) differ from metropolitan area networks (MANs), wide area networks (WANs), and backbone networks (BNs)?
A Local Area Network (LAN) is a group of microcomputers or terminals located in the same general area.
A Backbone Network (BN) is a large central network that connects most everything on a single company site.
A Metropolitan Area Network (MAN) encompasses a city or county area.
A Wide Area Network (WAN) spans cities, states, or national boundaries.
Explain how a message is transmitted from one computer to another using layers.
When a message is transmitted from one computer to another through these seven layer protocols are wrapped around the data, the layers in the network use a formal language or protocol that is a set of instructions of what the layer will do to the message, these ...view middle of the document...
The network layer takes the message generated by the application layer and if necessary, breaks it into several smaller messages. It then addresses the message(s) and determines their route through the network, and records message accounting information before passing it to the data link layer.
The data link layer formats the message to indicate where it starts and ends, decides when to transmit it over the physical media, and detects and corrects any errors that occur in transmission.
The physical layer is the physical connection between the sender and receiver, including the hardware devices (e.g., computers, terminals, and modems) and physical media (e.g., cables, and satellites).
When the server receives the web request message the whole process is reversed. The Ethernet frame is “unpacked” going back through each layer until it reaches the application layer and the message is read. The process is then started again as the web page requested is sent back in another message, to the person requesting it.
Describe two important data communications standards-making bodies. How do they differ?
International Organization for Standardization, One of the most important standards-making bodies is the International Organization for Standardization (ISO), which makes technical recommendations about data communication interfaces (see www.iso.org). ISO is based in Geneva, Switzerland. The membership is composed of the national standards organizations of each ISO member country.
International Telecommunications Union—Telecommunications Group - The Telecommunications Group (ITU-T) is the technical standards-setting organization of the United Nations International Telecommunications Union, which is also based in Geneva (see www.itu.int). ITU is composed of representatives from about 200 member countries. Membership was originally focused on just the public telephone companies in each country, but a major reorganization in 1993 changed this, and ITU now seeks members among public- and private-sector organizations who operate computer or communications networks (e.g., RBOCs) or build software and equipment for them (e.g., AT&T).