Topics: Computer network, Local area network, Network topology Pages: 6 (1322 words) Published: May 3, 2013
* Computer Network
* Any system of interconnected computers, computer peripheral equipments used for transmit and receive of information. * Applications of Networks
* Resource Sharing
* Hardware (computing resources, disks, printers)
* Software (application software)
* Information Sharing
* Easy accessibility from anywhere (files, databases) * Search Capability (WWW)
* Communication
* Email
* Message broadcasting
* Components of a Network
A computer network typically includes four things:
1. Network interface cards (NICs)
2. Networking Software
3. Networking Media
4. Networking Devices
* Network interface cards (NICs):
* Plugs into the back of your computers and lets them send and receive messages from other computers * The MAC address is a 48 bit long unique value associated with a network adapter. * MAC addresses are also known as hardware addresses or physical addresses. * IP Address

* Every machine on the Internet has a unique identifying number, called an IP Address. * A typical IP address looks like this:
* Computers communicate in binary form. Look at the same IP address in binary:
* Networking Software
* The basic communication language or protocol of the Internet. * The TCP/IP model has four layers.
* Each layer performs a certain role or task.
* Each layer a packet of information travels through adds what is called a header. * TCP/IP
Data Communication Example
* Networking Devices
All networks are made up of basic hardware building blocks to interconnect network nodes, such as: * Hubs
* Switches
* Routers
* Building an Internetworking using Router
* An Internetwork is a collection of individual networks, connected by intermediate networking devices that function as a single large network. * A router is needed to connect individual networks.

* Router maintains routing table to keep track of individual networks. * Networking Media
* Networking media can be defined simply as the means by which signals (data) are sent from one computer to another (either wired or wireless means). * Physical communications Channels

* Twisted Pair
* uses copper wire, twisted together in pairs to form a telephone wire. * Maximum segment length of 100 meters
* Coaxial Cable/Co-ax
* uses one or more central wire conductors surrounded by an insulator and encased in metal sheathing. * thin coaxial cable is able to transport a signal up to around 185 meters without line loss. * thick coaxial cable is able to carry signals over long distances: up to 500 meters without line loss * Fiber-optic Cable

* A physical communications channel that uses light and glass fibers. * It is light-weight and tolerates data rates on the order of 100Mbps up to 60km. * Wireless Channels
Wireless channels transmit data through air or space
* Radio Waves
* RF frequency ranges from roughly 30 kilohertz to 1 gigahertz * A radio wave is an electromagnetic wave propagated by an antenna. * All FM radio stations transmit in a band of frequencies between 88 megahertz and 108 megahertz. * Microwave

* Microwaves frequency ranges between 1 GH(109 Hz) to 1 TH (1012 Hz). * Networking Media
* They are the principal carriers of television, telephone, and data transmissions between stations on Earth and between the Earth and satellites. * Radar beams are short pulses of microwaves used to locate ships and planes etc. * Infrared

* Transmits data and information by means of an infrared light. The signal cannot travel through objects. * commonly used in remote control of TVs, VCRs and CD players * Network Topology

* The network...
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