1. NETWORK TOPOLOGY
1.1. DEFINITION
1.1.1. Refers to the layout of the nodes (computers and devices) in a communications network.
1.2. LAYOUT OF NETWORK
1.2.1. Physical topology
1.2.1.1. The arrangement of a cabling.
1.2.2. Logical topology
1.2.2.1. The path that data travels between computers on a network.
1.3. TYPES OF NETWORK TOPOLOGY
1.3.1. Bus network topology
1.3.1.1. Consists of a single central cable (backbone) to which all computers and other devices connect.
1.3.1.2. ADVANTAGES
1.3.1.2.1. - Inexpensive and easy to install.
1.3.1.2.2. - Other devices can be attached or detached without disturbing the network.
1.3.1.2.3. - Failure of one device does not affect the rest of the network.
1.3.1.3. DISADVANTAGES
1.3.1.3.1. - There might be distruption when computer or other devices are added or removed.
1.3.1.3.2. - The break in the main cable will prevent all systems from accessing the network.
1.3.1.3.3. - It is difficult to identify the problem if the entire network shut down.
1.3.2. Star network topology
1.3.2.1. All the computers an other devices on the network connect to a central device, thus forming a star.
1.3.2.2. ADVANTAGES
1.3.2.2.1. - If one device fails, only that device is affected.
1.3.2.2.2. - Devices can be added or removed from network with no disruption.
1.3.2.2.3. - Easy to troubleshoot and isolate problem.
1.3.2.3. DISADVANTAGES
1.3.2.3.1. - If the hub or switch fails, the entire network will be inoperabled.
1.3.2.3.2. - Requires more cables than most of the other topologies.
1.3.2.3.3. - More expensive because of the cost of hub/switch.
1.3.3. Ring network topology
1.3.3.1. A cable forms a closed loop (ring) with all computers and devices arranged along the ring.
1.3.3.2. ADVANTAGES
1.3.3.2.1. - Transmission of data is simple as packets travel in one direction only.
1.3.3.2.2. - Cable faults are easily located, making troubleshooting easier.
1.3.3.2.3. - All devices share the network resources fairly.
1.3.3.3. DISADVANTAGES
1.3.3.3.1. - A failure in any cable or device breaks the loop and can take down entire network.
1.3.3.3.2. - Data packets must pass through every computer thus make it slower.
1.3.3.3.3. - More difficult to install than a bus network.
2. CLASSIFICATION OF NETWORK
2.1. LOCAL AREA NETWORK (LAN)
2.1.1. DEFINITION
2.1.1.1. A network that connects computers and devices in a limited geographical area such as home and lab.
2.1.2. ADVANTAGES
2.1.2.1. . Easy to share devices (printers, scanners, external drives)
2.1.2.2. - Easy to share (homework, pictures)
2.1.2.3. - Cost of LAN setup is low.
2.1.3. DISADVANTAGES
2.1.3.1. - POWER - a good LAN is required to be 'ON' all the times.
2.1.3.2. - SECURITY - each computer and device become another point of entry for undesirables.
2.1.3.3. - Can REDUCE SPEED for each if all computers running at once.
2.1.3.4. - Area covered is LIMITED.
2.2. METROPOLITAN AREA NETWORK (MAN)
2.2.1. DEFINITION
2.2.1.1. A high-speed network that connects local area networks such as a city or town.
2.2.2. EXAMPLES
2.2.2.1. . Surveillance System
2.2.2.2. . Traffic Light Monitoring System
2.2.2.3. . Cable Network TV
2.2.3. TYPE OF MAN
2.2.3.1. Campus Area Network (CAN)
2.2.3.1.1. - A campus network is a computer network made up of an interconnection of local area networks (LAN's)
2.2.4. ADVANTAGES
2.2.4.1. - Efficiency and shared access.
2.2.4.2. - All the compter-owning residents of the area have equal ability to go on line.
2.2.5. DISADVANTAGES
2.2.5.1. - It can be costly (hardware, software, support, etc.)
2.2.5.2. - Security problems
2.2.5.3. - As the network consists of many computers over the span of a city, the connection can lag or become quite slow.
2.3. WIDE AREA NETWORK (WAN)
2.3.1. DEFINITION
2.3.1.1. A network that covers a large geographical area such as a city, country and world using a communications channel that combines many types of media such as telephone lines, cables and radio waves.
2.3.2. ADVANTAGES
2.3.2.1. - Increase efficiency, ease of communication and lowered costs.
2.3.3. DISADVANTAGES
2.3.3.1. . Security problems
2.3.3.2. . Training costs
2.3.3.3. . Maintenance problems. Large enterprises will dedicate personnel to maintaining their WAN.
3. INTRODUCTION
3.1. DEFINITION
3.1.1. NETWORK is a collection of computers and devices connected together via communication device and transmission media to share resources.
3.2. COMMUNICATIONS SYSTEM
3.2.1. SENDING DEVICE - Initiates an instruction to transmit data, instructions or information.
3.2.2. COMMUNICATIONS DEVICE - Connects the sending device to a communications channel.
3.2.2.1. - Hardware or equipment which are designed to transfer signals or data from a sender to receiver.
3.2.2.1.1. EXAMPLE
3.2.3. TRANSMISSION MEDIA - Which the data, instructions or information travel.
3.2.3.1. - Transmission media consist of materials or substances capable of carrying one or more signals.
3.2.3.1.1. WIRED
3.2.3.1.2. WIRELESS
3.2.4. COMMUNICATIONS DEVICE - Connects the communications channel ta a receiving device.
3.2.5. RECEIVING DEVICE - Accepts the transmission of data, instructions or information.
3.3. ADVANTAGES
3.3.1. Facilitating communications
3.3.1.1. - People communicate efficiently and easily via chat applications
3.3.2. Sharing hardware
3.3.2.1. - Each computer on the network can have access to all hardware on the network.
3.3.3. Sharing data and information
3.3.3.1. - Any authorized computer user can access data and information stored o other computers
3.3.4. Sharing software
3.3.4.1. - Users connected to a network have access to software on the network.
3.3.5. Transferring funds
3.3.5.1. - Allows user connected to a network to transfer money from one bank account to another via transmission media.
3.4. DISADVANTAGES
3.4.1. Virusses
3.4.1.1. - The virus can spread itself electronically at computer speeds.
3.4.2. Network failure
3.4.2.1. - Nobody can do any work if the file server fails then no one on the network can access any files or folders.
3.4.3. Slow service
3.4.3.1. - The network can start to slow down when more users log onto the network.
3.4.4. Cost
3.4.4.1. - Every workstation needs a network interface interface card to enable it to be connected to the network.
3.4.5. Expert support required
3.4.5.1. - Networks need constant monitoring to ensure that the performance is maintained and that all the components are working properly.
4. NETWORK ARCHITECTURE
4.1. DEFINITION
4.1.1. The design of computers, devices and media on a network.
4.2. PEER-TO-PEER
4.2.1. Each computer , called a peer has equal responsibilities and capabilities, sharing hardware (such as a printer), data and information with other computers.
4.3. CLIENT-SERVER
4.3.1. One or more computers act as a server and the other computers on the network request services from the server.
4.3.1.1. CLIENT - other computers and mobile devices on the network that rely on the server for its resources.
4.3.1.2. SERVER - Controls access to the hardware, software and other resources on the network and provides a centralized storage area for programs, data and information.
4.4. PEER-TO-PEER VS CLIENT-SERVER
4.4.1. PEER-TO-PEER
4.4.1.1. * Every user is taking care of his/her own machine so could be difficult to administer the network.
4.4.1.2. * Easy to install and configure for the computers in the network.
4.4.1.3. * Cost to install and maintain network is inexpensive.
4.4.1.4. * Each computer has equal responsibilities and capabilities.
4.4.2. CLIENT-SERVER
4.4.2.1. *Centralized control by the server can be more efficient at administering the whole network.
4.4.2.2. * Network professionals are normally needed to manage and maintain the whole network.
4.4.2.3. * Cost to install and manage the network can be expensive.
4.4.2.4. * Only server have high responsibilities and capabilities.