The topic in this lecture is securiy in network. A computer network is a group of computers that are connected to each other for the purpose of communication. Networks may be classified according to a wide variety of characteristics. This article provides a general overview of some types and categories and also presents the basic components of a network.
One way to categorize the different types of computer network designs is by their scope or scale. For historical reasons, the networking industry refers to nearly every type of design as some kind of area network. Common examples of area network types are:
• LAN - Local Area Network
• WLAN - Wireless Local Area Network
• WAN - Wide Area Network
• MAN - Metropolitan Area Network
• SAN - Storage Area Network, System Area Network, Server Area Network, or sometimes Small Area Network
1. Bus - Both ends of the network must be terminated with a terminator. A barrel connector can be used to extend it.
2. Star - All devices revolve around a central hub, which is what controls the network communications, and can communicate with other hubs. Range limits are about 100 meters from the hub.
3. Ring - Devices are connected from one to another, as in a ring. A data token is used to grant permission for each computer to communicate.
Advantages of network
Speed-Sharing and transferring files within Networks are very rapid. Thus saving time, while maintaining the integrity of the file.
Cost-Individually licensed copies of many popular software programs can be costly. Networkable versions are available at considerable savings. Shared programs, on a network allows for easier upgrading of the program on one single file server, instead of upgrading individual workstations.
Security-Sensitive files and programs on a network are passwords protected (established for specific directories to restrict access to authorized users) or designated as "copy inhibit," so that you do not have to worry about illegal copying of programs.
Centralized Software Management-Software can be loaded on one computer (the file server) eliminating that need to spend time and energy installing updates and tracking files on independent computers throughout the building.
Resource Sharing-Resources such as, printers, fax machines and modems can be shared.
Electronic Mail-E-mail aids in personal and professional communication. Electronic mail on a LAN can enable staff to communicate within the building having tot to leave their desk.
Flexible Access-Access their files from computers throughout the firm.
Workgroup Computing-Workgroup software (such as Microsoft BackOffice) allows many users to work on a document or project concurrently.
Disadvantages of network
• Server faults stop applications being available
• Network faults can cause loss of data.
• Network fault could lead to loss of resources
• User work dependent upon network
• System open to hackers
• Decisions tend to become centralised
• Could become inefFicient
• Could degrade in performance
• Resources could be located too far from users
• Network management can become dif
