Networks Are you Wired?

Networking A network is defined as two or more computers connected together –Peer-to-peer when a server is not involved. –Client-server when a server is involved.

How do I connect … You need a Network Interface Card (NIC) Most newer PCs include an Ethernet port on the main circuit board, so they don’t require NICs to connect to Ethernet networks

Communication á la Modem Modem: a hardware device that connects a computer’s serial port to a telephone line (for remote access) May be internal on the system board or external, sitting in a box linked to a serial port Modem transmission speed is measured in bits per second (bps) and modems generally transmit at 28,000 bps to 56.6K bps Computers send digital signals and the modem converts them to analog

Broadband Connection much greater bandwidth than modems DSL uses standard phone lines and is provided by phone companies in many areas Cable modems provide fast network connections through cable television networks in many areas High-speed wireless connections can connect computers to networks using radio waves rather than wires Satellite dishes can deliver fast computer network connections as well as television programs

Fiber Optic Connections DSL and cable modems have no where near the bandwidth of the fiber optic cables that are replacing copper wires in the worldwide telephone network A fiber optic network can rapidly and reliably transmit masses of multimedia data at the same time that it’s handling voice messages

Local Area Network (LAN) Uses and Benefits of a LAN –Security through id and password –Shared peripherals –Shared storage –Shared Applications –Reliability and Resilience –Centralized backup systems for data recovery –Centralized virus protection –New ways to work together

LAN vs WiFi A LAN, computers are physically close to each other, usually in the same building. In a wireless network each node has a tiny radio (or, less commonly, infrared) transmitter connected to its network port –Sends and receives data through the air rather than through cables –Each computer and peripheral is an individual node on the network –Nodes are connected by cables which may be either twisted pair (copper wires) or coaxial cable

Wireless Network Technology When bandwidth is less important than mobility and portability, wireless technology can provide practical solutions Another type of wireless technology is Named for a Danish king who overcame his country’s religious differences Overcomes differences between mobile phones, handheld computers, and PCs, making it possible for all of these devices to communicate with each other regardless of operating system

Bluetooth PAN With Bluetooth it’s possible to create a personal area network (PAN)—a network that links a variety of personal electronic devices so they can communicate with each other Bluetooth technology is currently limited to simple device connectivity, but in the future it will open up all kinds of possibilities: –A pacemaker senses a heart attack and notifies the victim’s mobile phone to dial 911 –A car radio communicates with parking-lot video cameras to find out where spaces are available

Wide Area Network (WAN) A computer network that spans a relatively large geographical area. Typically, a WAN consists of two or more LANs. The largest WAN being the Internet itself.

Networks TypeUsesMax Distance Cost Twisted pair Small LANs 300 feetLow Coxial cable Large LANs feet Medium Fiber Optic Network backbones WANs 1-25 milesHigh WirelessLANs feetMedium Wireless/ radio Moving Objects VariesHigh

Specialized Networks: From GPS to Financial Systems Global Positioning System (GPS) –Specialized network developed by U.S. Department of Defense –Includes 24 satellites that circle the Earth –Each satellite contains a computer, an atomic clock, and a radio –On the ground, a GPS receiver can use signals broadcast by three or four visible satellites to determine its position Networks that keep our global financial systems running: –An Automated Teller Machine (ATM): a specialized terminal linked to a bank’s main computer through a commercial banking network

Types of Networks Star Network –Centralized hub (typical systems) –Each machine runs independently from the other, but hubs connect. Ring Network –All machines arranged in a ring –Built in redundancy with dual-ring –Fibre optics and token ring Bus Network –All machines on the same line –Difficult to repair but inexpensive to construct

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