Section+1+-+Week+10+-+How+the+Internet+Works

media type="youtube" key="YU3KR7pHYw0" height="315" width="560"media type="youtube" key="7_LPdttKXPc" height="315" width="420"media type="youtube" key="g6NMFHuef6Y" height="315" width="420" Networking article Vocabulary words: http://lis3353.wikispaces.com/Lab+A8+-+Networking+Terminology+Glossary

**XHTML**- A markup language for Web pages from the W3C. _ combines HTML and XML into a single format (HTML 4.0 and XML 1.0). Like XML, XHTML can be extended with proprietary tags and (also like XML) must be coded more rigorously than HTML. HTML expressed as valid XML. XHTML is to be used in the same places you would use HTML (creating web pages) but is much more strictly defined.

A network is a collection of computer systems configured to share digital data and resources.

Computer to computer : Sender<-Channel->Receiver Message-->Signal--->Message


 * Using “ping” or “traceroute,” you can discover the length of time that data is in transit


 * On average, data within the US usually arrives at its destination 110-120 milliseconds (ms) after it is sent


 * Overseas transmissions require a little more time


 * NetTraffic


 * Network Monitors-**
 * Keep track of network traffic, number of packets, packet size, collisions, re-transmissions, etc.


 * Enable planning for growth and quality


 * Network Analyzers-**


 * Randomly dissect packets, analyze problems, and determine the source of errors


 * Web entry stations that offer quick and easy access to a variety of services**
 * Consumer portals include search engines, e-mail services, chat rooms, references, news headlines, shopping malls, and other services
 * Corporate portals on intranets serve the employees of particular corporations
 * Vertical portals are targeted at members of a particular industry or economic sector


 * Other Web Stuff**
 * Push (auto-updates) versus Pull (browser in client-server model) technology


 * Nets-**
 * Intranets
 * Extranets
 * Electronic data interchange (EDI)

layers || [|Data] || 7. [|Application] || Network process to application || layers || [|Packet]/[|Datagram] || 3. [|Network] || Path determination and [|logical addressing] || >>>> >>>> **Nets**
 * ~ OSI Model ||
 * ~  ||~ Data unit ||~ Layer ||~ Function ||
 * ~ Host
 * ^  ||^   || 6. [|Presentation] || Data representation, encryption and decryption, convert machine dependent data to machine independent data ||
 * ^  ||^   || 5. [|Session] || Interhost communication, managing sessions between applications ||
 * ^  || [|Segments] || 4. [|Transport] || End-to-end connections, reliability and [|flow control] ||
 * ~ Media
 * ^  || [|Frame] || 2. [|Data link] || [|Physical addressing] ||
 * ^  || [|Bit] || 1. [|Physical] || Media, signal and binary transmission ||
 * Why do we network
 * Reduces hardware and software costs
 * Provides access to a wide range of services and specialized peripheral devices
 * Enables people to work together, regardless of time and place
 * Network 101
 * Network Topography
 * May be physical or logical
 * Physical Topography
 * relates to a core network whereas logical topology relates to basic network
 * the physical design of a network including the devices, location and cable installation
 * Logical Topography
 * refers to how data is actually transferred in a network as opposed to its physical design
 * Client/server
 * Contains servers and clients
 * Peer-to-peer
 * every computer is considered an equal
 * network
 * a collection of computer systems configured to share digital data and resources
 * types
 * computer-to-computer
 * LANs (Local Area Networks)
 * Connectivity supporting two-way communication
 * Resource sharing
 * They extend across limited Geographical area
 * Servers, terminals, etc
 * Transparency of use
 * Support from hardware and software
 * Positives
 * communications
 * management control
 * cost-effectiveness
 * Negatives
 * need for additional equipment
 * maintenance
 * support staff
 * The defining characteristics of LANs, in contrast to wide area networks (WANs),
 * usually higher data-transfer rates
 * smaller geographic area
 * lack of a need for leased telecommunication lines
 * WAN (Wide Area Network)
 * 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
 * OFTEN OWNED BY SINGLE CORP
 * MAN (Metropolitan Area Network)
 * a computer network that usually spans a city or a large campus.
 * It interconnects a number of local area networks (LANs) using a high-capacity backbone technology, such as fiber-optical links
 * It provides up-link services to wide area networks (or WAN) and the Internet.
 * PAN (Personal Area Network)
 * a computer network used for communication among computerized devices, including telephones and personal digital assistants
 * It 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)
 * Intranets--collection of private computer networks within an organization
 * Extranets--computer network that allows controlled access from the outside for specific business or educational purposes.

Networking:

-Packet Switching:
 * The message is made of separate data packets, each addressed to the destination
 * Packets are transmitted over any available connection to the destination
 * The receiving node reassembles the message

Connecting:

-Modem / Dial-up -Modulation – changing the characteristics of a signal (digital to analog)
 * “modem” = modulate-demodulate

-Demodulation – changing the signal back to its original state (analog to digital)

Cables:

-Most networks use twisted-pair cables UTP (unshielded twisted pair) STP (shielded twisted pair) Looks similar to telephone cable Has a square plastic RJ-45 connector

-Twisted Pair Wire Cable Insulated pairs of wires historically used in telephone service Category 1 – Telephones Category 3 – Up to 10Mbps Category 5 – Up to 100Mbps

-Another option is coaxial cable Resembles cable-TV cable Round, silver BNC or F-type connector

-Coaxial Cable (BNC)
 * Consists of an inner conductor wire surrounded by insulation, called the dielectric. The dielectric is surrounded by a conductive shield, which is surrounded by a non-conductive jacket. Coaxial cable has a better data transmission rate than twisted pair.

-Fiber-optic cable is a bundle of extremely thin tubes of glass
 * Many extremely thin fibers of glass or plastic, coated with a cladding and bound together in a sheathing which transmits signals with light beams
 * Fast transfer rates
 * Immune to electrical interference (emi occurs over long distances)
 * Hard to tap into
 * Takes less space
 * Each optical fiber (tube) is thinner than a human hair

Networks:

-Repeaters boost the signal strength over transmission medium -Bridges isolate LANs from unnecessary traffic, but connect LANs to neighboring networks

-TCP/IP: Internet protocol suite is the set of communications protocols used for the Internet and similar networks, and generally the most popular protocol stack for wide area networks.Provides end-to-end connectivity specifying how data should be formatted, addressed, transmitted, routed and received at the destination

-IP address: is a numerical label assigned to each device (e.g., computer, printer) participating in a computer network that uses the Internet Protocol for communication.An IP address serves two principal functions: host or network interface identification and location addressing. -An IP address is a series of numbers, such as 204.127.129.001

-Domain names are pseudonyms for IP addresses

-Protocols: A communications protocol is a set of rules for efficiently transmitting data from one network node to another The best-known protocol is probably TCP/IP

-Sending Computer: Breaks the data into packets; adds addressing information; prepares the data for transmission

-Receiving Computer: Takes packets off the cable; strips the packets of addressing information; reassembles the data from the packets

-TCP/IP provides a standard that is public, free, extensible, and fairly easy to implement. TCP/IP is the glue that holds the Internet together.

-ISPs need static IP addresses

-Numbers are hard to remember, so host computers also have names called domain names; a domain names corresponds to an IP address; domain name system – huge database that houses the names and IP addresses of key computers

-Domain name servers – computers that house this database

Internet 2- consortium of government, industry, and education

The consortium- establishes network capabilities to support national research develops the next generation of Internet applications transfers these to worldwide Internet Internet 2- remote instrumentation and virtual laboratories distance learning digital libraries Tele-immersion multicasting

National LambdaRail- High-speed national network running on fiber LambdaRail will merge with I2 Testing service network University-based and -owned initiative

Wireless infrared broadcasting radio frequency broadcasting spread spectrum (cell telephony) direct sequence spread spectrum (DSSS) frequency hopping spread spectrum (FHSS)