1. From Analog to Digital Analog Most phenomena in life are analog. Analog signals use wave variations, continuously changing. Sound, light, and temperature are analog forms. Traditional TV and radio use analog signals. Humans' vision operates in analog mode.
Peer to Peer All computers on the network are "equal" and communicate directly with one another, without relying on a server. Easy to setup Less expensive Work effectively for up to 25 computers Slow down under heavy use
Client-Server Clients are microcomputers that request data. Servers are central computers used to supply data. File server is a computer acts like a disk drive, storing the programs and data files. Database server is a computer that stores data but doesn’t store programs. Print server controls one or more printers and stores the print-image output. Web server contains web pages. Mail server manages email.
5. Intranet Intranet is an organization’s internal private network that serves employee only.
6. Extranet Extranet is private intranets that connect internal personnel and selected suppliers and other parties such as purchasing, production planning.
7. VPN (Virtual Private Networks) VPNs use a public network (usually the internet) plus intranets and extranets to connect an organization's various sites but on a private basis, via encryption and authentication; regular internet users do not have access to the VPNs data and information.
8. Firewall Protect Network from Intruders FIREWALL Networking Basic https://www.youtube.com/watch?v=- xnqC2aPb00 https://www.youtube.com/watch?v=- xnqC2aPb00 Software Firewall > One computer Hardware Firewall > Many computers
9.1 Host & Nodes Host computer controls the network Node is any device that is attached to a network. – Computer – Storage devices – Scanner – Printer
9.2 Packet A packet is a fixed-length block of data for transmission. A sending computer breaks an electronic message apart into packets, each of which typically contains 1000-1500 bytes. http://youtube.com/watch?v=n4H26PlmfaQ https://www.youtube.com/watch?v=3_EHaM 3tr98 https://www.youtube.com/watch?v=3_EHaM 3tr98
9.3 Protocol Protocol is a set of conventions governing the exchange of data between hardware and software components in a communication network.
Switch A switch is a device that connects computers to a network and facilitates communication by sending message between sender and receiver nodes.
9.4.2 Bridge A bridge is a device used to connect two similar networks, LAN and LAN A bridge has a single connection point.
9.4.3 Gateway A gateway is an interface permitting communication between dissimilar network, LAN and WAN
9.4.4 Router Routers are specialized devices for transmitting data, physical devices that join multiple networks. Router calculates the best possible transmission path of data packets between networks.
9.5 Network Interface Card Network interface card enables the computer to send and receive messages over a cable network.
Star All computers and other communication devices are directly connected to a switch. The switch prevents collisions between messages. If a connection is broken, the rest of the devices will continue operating. If the switch goes down, the entire network stops.
Ring All computers and other devices are connected in a continuous loop. Messages are passed around the ring until they reach the destination. There is no central server. Messages flow in one direction. Thus, there is no collisions. If one node malfunctions, the entire network can stop working.
Bus All nodes are connected to a single wire. The bus has two endpoints, which stop the network signal. Advantage If some message collide, the sending device waits and tries to transmit again. Inexpensive, easy to use, good for small network Disadvantage Need extra software to avoid collision Limited to 20 devices Cannot exceed 185 meters in length
Mesh Each node has more than one connection to the other nodes so that a message can take any possible shortest, easiest route to reach its destination. If a path between two nodes is disrupted, data can be automatically rerouted along another path.
Fiber-optic Cable A fiber-optic cable consists of dozens of thin strands of glass or plastic that transmit pulsating beams of light rather than electricity. A fiber-optic cable can carry data at the rate of 2 gigabits per second. It is not affected by electromagnetic interference. It has a much lower error rate than telephone wire. It requires less power to transmit signals than co- ax cable.
12. Wireless Communications Media 12.1 Infrared Transmission 12.2 Broadcast Radio 12.3 Cellular Radio 12.4 Microwave Radio 12.5 Communications Satellites
12.1 Infrared Transmission Infrared wireless transmission sends data signals using infrared-light waves at a frequency too low for human eyes to receive and interpret. Infrared port can be found on TV remote- control. 1-16 megabits per second
12.2 Broadcast Radio Broadcast radio is a wireless transmission medium that send data over long distances at up to 2 megabits per second. Broadcast radio is used in AM and FM radio station.
12.3 Cellular Radio Cellular radio is used for cellphones and wireless modems, using high-frequency radio waves to transmit voice and digital messages.
12.4 Microwave Radio Microwave radio transmits voice and data at 45 megabits per second through the atmosphere as super high-frequency radio waves.
12.5 Communication Satellite Communications satellites are microwave relay stations in orbit around Earth.
13. Long-Distance Wireless One-way Communication > GPS, Pager Two-way Communication > 4G
14. Short-Distance Wireless Local area networks > range 100-228 feet > Wi-Fi Personal area networks > range 30-33 feet > Bluetooth Home automation network > range 100-150 feet > Insteon https://www.youtube.com/watch?v=YpuqceW 3qu8 https://www.youtube.com/watch?v=YpuqceW 3qu8