04-04-2012, 11:36 AM
network
[attachment=19423]
A network consists of two or more computers that are linked in order to share resources (such as printers and CD-ROMs), exchange files, or allow electronic communications. The computers on a network may be linked through cables, telephone lines, radio waves, satellites, or infrared light beams.
TYPES OF NETWORKS
The three basic types of networks include: LAN, MAN and WAN.
LOCAL AREA NETWORK (LAN)
A network is said to be Local Area Network (LAN) if it is confined relatively to a small area. It is generally limited to a building or a geographical area, expanding not more than a mile apart to other computers.
LAN configuration consist of:
A file server - stores all of the software that controls the network, as well as the software that can be shared by the computers attached to the network.
A workstation - computers connected to the file server (Mac or PCs). These are less powerful than the file server
Cables - used to connect the network interface cards in each computer.
METROPOLITAN AREA NETWORK (MAN)
Metropolitan Area Network (MAN) covers larger geographic areas, such as cities. Often used by local libraries and government agencies often to connect to citizens and private industries.
WIDE AREA NETWORK (WAN)
Wide Area Networks (WANs) connect larger geographic areas, such as London, the UK, or the world. In this type of network dedicated transoceanic cabling or satellite uplinks may be used.
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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
OSI MODELS
The standard model for networking protocols and distributed applications is the International Standard Organization's Open System Interconnect (ISO/OSI) model. It defines seven network layers.
Layer 1 - Physical
This layer defines the cable or physical medium itself, e.g. unshielded twisted pairs (UTP). All media of transmission are functionally equivalent in this layer and the main difference is in convenience and cost of installation and maintenance.
Layer 2 - Data Link
Data Link layer defines the format of data on the network ( a network data frame, packet and destination address). The Maximum Transmission Unit (MTU) is defined by the largest packet that can be sent through a data link layer.
Layer 3 - Network
This layer defines the protocols that are responsible for data delivery at the required destination, and requires.
Layer 4 - Transport
This layer subdivides user-buffer into network-buffer sized datagrams and enforces desired transmission control. Two transport protocols, Transmission Control Protocol (TCP) and User Datagram Protocol (UDP), sits at the transport layer. Reliability and speed are the primary difference between these two protocols.
[attachment=19423]
A network consists of two or more computers that are linked in order to share resources (such as printers and CD-ROMs), exchange files, or allow electronic communications. The computers on a network may be linked through cables, telephone lines, radio waves, satellites, or infrared light beams.
TYPES OF NETWORKS
The three basic types of networks include: LAN, MAN and WAN.
LOCAL AREA NETWORK (LAN)
A network is said to be Local Area Network (LAN) if it is confined relatively to a small area. It is generally limited to a building or a geographical area, expanding not more than a mile apart to other computers.
LAN configuration consist of:
A file server - stores all of the software that controls the network, as well as the software that can be shared by the computers attached to the network.
A workstation - computers connected to the file server (Mac or PCs). These are less powerful than the file server
Cables - used to connect the network interface cards in each computer.
METROPOLITAN AREA NETWORK (MAN)
Metropolitan Area Network (MAN) covers larger geographic areas, such as cities. Often used by local libraries and government agencies often to connect to citizens and private industries.
WIDE AREA NETWORK (WAN)
Wide Area Networks (WANs) connect larger geographic areas, such as London, the UK, or the world. In this type of network dedicated transoceanic cabling or satellite uplinks may be used.
top
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
OSI MODELS
The standard model for networking protocols and distributed applications is the International Standard Organization's Open System Interconnect (ISO/OSI) model. It defines seven network layers.
Layer 1 - Physical
This layer defines the cable or physical medium itself, e.g. unshielded twisted pairs (UTP). All media of transmission are functionally equivalent in this layer and the main difference is in convenience and cost of installation and maintenance.
Layer 2 - Data Link
Data Link layer defines the format of data on the network ( a network data frame, packet and destination address). The Maximum Transmission Unit (MTU) is defined by the largest packet that can be sent through a data link layer.
Layer 3 - Network
This layer defines the protocols that are responsible for data delivery at the required destination, and requires.
Layer 4 - Transport
This layer subdivides user-buffer into network-buffer sized datagrams and enforces desired transmission control. Two transport protocols, Transmission Control Protocol (TCP) and User Datagram Protocol (UDP), sits at the transport layer. Reliability and speed are the primary difference between these two protocols.