Computer Networks

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Networking

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Computer Networks A computer network is a system for communicating between two or more computers and associated devices. It is an interconnection of computers for the purposes of sharing information and resources. A popular example of a computer network is the internet, which allows millions of users to share information Computer networks can be classified according to their size: Personal area network (PAN) Local area network (LAN) Metropolitan area network (MAN) Wide area network (WAN)

An example of a network : 

3 An example of a network Router Internet Segment Node Hub Hub Bridge

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A personal area network (PAN) is a computer network used for communication among computerized devices, including telephones and personal digital assistants. PANs can be used for communication among the personal devices themselves (intrapersonal communication), or for connecting to a higher level network and the Internet (an uplink). Personal Area Network

Wide Area Network : 

Wide Area Network A wide area network (WAN) is a telecommunication network that covers a broad area (i.e., any network that links across metropolitan, regional, or national boundaries). Business and government entities utilize WANs to relay data among employees, clients, buyers, and suppliers from various geographical locations. In essence this mode of telecommunication allows a business to effectively carry out its daily function regardless of location.

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Local Area Network A local area network (LAN) is a computer network that interconnects computers in a limited area such as a home, school, computer laboratory, or office building. The defining characteristics of LANs, in contrast to wide area networks (WANs), include their usually higher data-transfer rates, smaller geographic area, and lack of a need for leased telecommunication lines.

Ethernet : 

Ethernet  is a family of computer networking technologies for local area networks(LANs) commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies. Systems communicating over Ethernet divide a stream of data into individual packets called frames. Ethernet

Network Topologies : 

Bus Topology Each node is connected one after the other (like Christmas lights) Nodes communicate with each other along the same path called the backbone 8 Network Topologies

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The ring network is like a bus network, but the “end” of the network is connected to the first node Nodes in the network use tokens to communicate with each other Backbone Ring Topology

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Each node is connected to a device in the center of the network called a hub The hub simply passes the signal arriving from any node to the other nodes in the network The hub does not route the data Star Topology

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Branching Tree Topology

Types of Ethernet LANs : 

10Base-T Operates at 10 Mbps IEEE 802.3 standard Fast Ethernet (100Base-T) Operates at 100 Mbps Gigabit Ethernet Operates at 1 Gbps Uses fiber optic cable 10 Gbps Ethernet Latest development of Ethernet Uses fiber optic cable Developed to meet the increasing bandwidth needs of the LAN market Wireless Ethernet IEEE 802.11 standard Operates at around 2.4 Gbps Types of Ethernet LANs

Fiber-Distributed Data Interface (FDDI) : 

Fiber-Distributed Data Interface (FDDI) provides a standard for data transmission in a local area network that can extend in range up to 200 kilometers (124 miles). The FDDI protocol uses as its basis the token ring protocol. In addition to covering large geographical areas, FDDI local area networks can support thousands of users. As a standard underlying medium it uses optical fiber (though it can use copper cable, in which case one can refer to CDDI). FDDI uses a dual-attached, counter-rotating token-ring topology. Fiber-Distributed Data Interface (FDDI)

Optical Fiber Cable : 

An optical fiber cable is a cable containing one or more optical fibers. The optical fiber elements are typically individually coated with plastic layers and contained in a protective tube suitable for the environment where the cable will be deployed. Optical Fiber Cable

Coaxial Cable : 

Coaxial cable, or coax, has an inner conductor surrounded by a flexible, tubular insulating layer, surrounded by a tubular conducting shield. The term coaxial comes from the inner conductor and the outer shield sharing the same geometric axis. Coaxial cable was invented by English engineer and mathematician Oliver Heaviside, who patented the design in 1880. Coaxial Cable

Twisted Pair Cable : 

Twisted pair cabling is a type of wiring in which two conductors (the forward and return conductors of a single circuit) are twisted together for the purposes of canceling out electromagnetic interference (EMI) from external sources; for instance, electromagnetic radiation from unshielded twisted pair (UTP) cables, and crosstalk between neighboring pairs. It was invented by Alexander Graham Bell. Twisted Pair Cable

WIRELESS NETWORKING : 

WIRELESS NETWORKING Wireless network refers to any type of computer network that is not connected by cables of any kind. It is a method by which homes, telecommunications networks and enterprise (business) installations avoid the costly process of introducing cables into a building, or as a connection between various equipment locations. Wireless telecommunications networks are generally implemented and administered using a transmission system called radio waves. This implementation takes place at the physical level (layer) of the network structure.

Bluetooth : 

Bluetooth is a proprietary open wireless technology standard for exchanging data over short distances (using short wavelength radio transmissions in the ISM band from 2400-2480 MHz) from fixed and mobile devices, creating personal area networks (PANs) with high levels of security. Created by telecoms vendor Ericsson in 1994, it was originally conceived as a wireless alternative to RS232data cables. It can connect several devices, overcoming problems of synchronization. Bluetooth

Wireless Fidelity (Wifi) : 

Wi-Fi , is a mechanism for wirelessly connecting electronic devices. A device enabled with Wi-Fi, such as a personal computer, video game console, Smartphone, tablet, or digital audio player, can connect to a network resource such as the Internet via a wireless network access point. An access point (or hotspot) has a range of about 20 meters (65 ft) indoors and a greater range outdoors. Multiple overlapping access points can cover large areas. Wireless Fidelity (Wifi)

Radio Wave : 

Radio wave are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies from 300 GHz to as low as 3 kHz, and corresponding wavelengths from 1 millimeter to 100 kilometers. Like all other electromagnetic waves, they travel at the speed of light. Naturally occurring radio waves are made by lightning, or by astronomical objects. Radio Wave