Mis589 Text Book Question

Chapter 1

7) 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. Where as a metropolitan area network (MAN) encompasses a city or county area. Coming to wide area network (WAN) it spans city, state, or national boundaries. Finally coming to back bone network it is a large network that connects almost everything on a single company site.

MANs

The next larger network than LAN may be the Metropolitan Area Networks (MANs). MAN usually spans a geographical area that usually encompasses a city or county area. It interconnects various buildings or other facilities within this citywide area. For example, linkages can be established between two commercial buildings. A more recent use of MAN technology has been the rapid development of cellular phone systems.

WANs

A wide area network (WAN) is one that operates over a vast distance (e.g., nationwide). Its nodes may span cities, states, or national boundaries. This network interconnects computers, LANS, BNs, MANS, and other data transmission facilities. Typically, WAN will employ communications circuits such as long- distance telephone wires, microwaves and satellites. FOR example, nationwide automated teller machines used in banking represent a common application of a wide area network.

BAN's

A backbone network or network backbone is a part of computer network infrastructure that interconnects various pieces of network, providing a path for the exchange of information between different LANs or sub networks. A backbone can tie together diverse networks in the same building, in different buildings in a campus environment, or over wide areas. Normally, the backbone's capacity is greater than the networks connected to it.

A large corporation that has many locations may have a backbone network that ties all of the locations together, for example, if a server cluster needs to be accessed by different departments of a company that are located at different geographical locations. The pieces of the network connections (for example: Ethernet, wireless) that bring these departments together is often mentioned as network backbone. Network congestion is often taken into consideration while designing backbones.

Backbone networks should not be confused with the Internet backbone.

14) Explain how a message is transmitted from one computer to another using layer.

When a message is transmitted from one computer to another through these seven layers 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 protocols are labeled or encapsulated onto the data. You could think of the protocols as layers of paper with a message that only the individual layer understands. Each layer handles other aspect of the connection these will be discussed below.

The first layer is the application layer it controls what data is submitted and deals with communication links such as establishing authority, identifying communication partners and the level of privacy. It is not the interface of what the user sees the client program creates this. When a user clicks a web link the software on the computer which understands HTTP (such as internet explorer and Netscape communicator) transfers it into a HTTP request message.

The presentation layer may perform encryption and decryption of data, data compression and translation between different data formats. This layer is also concerned about displaying formatting and editing user inputs and outputs. A lot of requests such as website requests do not use the presentation layer also there is no software installed at the presentation layer and is therefore rarely used.

The session layer as the name suggests deals with organization of the session. The layer creates the connection between the applicants, enforces the rules for carrying session and if the session does fail the layer will try to reinstate the connection. When computers communicate they need to be in synchronization so that if either party fails to send information the session layer provides a synchronization point so the communication can continue.

The transport layer ensures that a reliable channel exists between the communicating computers. The