NETWORKS AND COMMUNICATION

History of Communication Middle Ages Communication and Transportation are linked Printing Press Guttenburg Telegraph Samuel Morse Telephone Alexander Graham Bell Internet

History of the Internet 1950’s XEROX developed Networked computers 1960’s – ARPANET - Originally a network connecting military installations to safeguard US military secrets in case of a nuclear attack 1970’s – Universities – shared resources 1980’s – Nerds 1990’s – Normal People

Physical Methods of Connectivity Wired Category 5 cable – Twisted Pair (4x2) Coaxial POTS FIOS Wireless Satellite TV (Disk Network) WiFi ( standard) 3G 4G (Phone Networks) Infrared (TV Remote control) Bluetooth

LAN vs WAN Local Area Network IHA,Small business Home Networks Wide Area Network Multinational Corporations Internet

How do computers Communicate TCP/IP Transfer Control Protocol / Internet Protocol Protocol used for most networks including the Internet Every computer on a network has its own IP address for that network. IP address consists of 4 bytes separated by periods – Over 4 billion possible addresses. All Internet IP’s are taken ?. ? are reserved for LANs

IP addresses – Static vs Dynamic Static IP addresses Some computers never change their IP address immaculateheartacademy.org = Ntserver121 (LAN) = Dynamic IP addresses – DHCP – Dynamic Host Control Configuration Most Home Routers are given a different available address every time they connect.

How does a computer get an IP address? Every Network device (laptop, smartphone, iPad, etc.) has a unique “MAC” address that never changes Consists of 6 hexadecimal pairs ( 00 3A BC 14 F3 29 ) Every LAN has a DHCP server When a device joins the network it sends a broadcast to every device it can find: “Are you a DHCP server? If so, give me an IP address.” The DHCP server answers and temporarily gives an IP address ( ) to your computer which it then uses to communicate with the network.

Packets of Data Data arrives in a series of addressed packets. Only a limited number of bytes (1000 – 4000) are transmitted in each packet. Each packet starts with the IP address. Your network card only accepts packets that are addressed to it. Your Internet browser reassembles the file as the packets arrive.

Hubs, Switches and Routers All three devices send packets over a network Hub – sends all packets out each port Switch – learns where each IP addresses lives and only sends packets down that switch Router – sends packets onto a different network

How a router works Your router is given an Internet IP address by your ISP. ie Your router gets a LAN IP address for your local network Any computer on your home network speaks to its default gateway (the router) using its local IP address. The router then speaks to the Internet, fetches your page and sends it to your computer.

Wired Bandwidth (Speed) LANs 10 mbs (megabits/sec) – Ethernet Older computers (> 10 years old) 100 mbs – Fast Ethernet 1000 mbs – Gigabit All new laptops and computers have a gigabit port for wired connections

WiFi Speeds – mbs (“B”) 54 mbs (“G”) 54 mbs (“A”) – used in some businesses 300 mbs (“N”) All standards are “backwards compatible”

ISP – Internet Service Providers Client computers must connect to a computer on the backbone of the Internet. Popular ISP’s in Bergen County: Optimum Online (cable) Verizon (FIOS)

WAN Bandwidth (Speed) FIOS – 50 mbs Optimum – 20 mbs 4G – 10 mbs 3G – 4 mbs Test your speed at speedtest.net

Browsers A browser is software on the client computer that is need to convert html text into a web page. Most popular – Google Chrome MS Internet Explorer Mozilla Firefox Apple Safari Opera

Analyzing a URL 1. Protocol 2. Domain Name or server 3. Folders 4. File Name

Protocol determines what type of data is being transmitted

Internet protocols http: – hypertext transfer protocol – by far the most common https: - secure (encrypted) ftp: - file transfer protocol mailto: – sends

Domain Name Name of the computer (server) that holds the desired information

DNS – Domain Name Server Large database of domain name sends the IP address back to the computer that requested the domain name. There are 7 “master” domain controllers on the Internet LANs have their own DNS. Networksolutions.com Network-tools.com – website that will display names and IP addresses Network-tools.com

Domain Name Domain Name Extensions (7 Original) 3 – letter.com - commercial.edu – educational (now just colleges).org – organization (usually non-profit ).net – internet related.gov – US federal government.mil – military.int – international databases

Additional Common Extensions.biz – businesses.info – information.name – individuals (john.smith.name).pro – professionals (johndoe.med.pro)

Domain Name Extensions 2 letter extensions Usually Country names.uk.jp.us.au.de.ch.tv Sometimes State names.nj.in.ca registration/popup-extensions.jsp

Subdomains There is a hierarchy working from the back of the URL:

Registering your own Domain You must have someplace to host the site- A computer with a static IP address running Web Server software It cost about $10 / year to register your name. Check availability of your name. Check availability Iha.netiha.comihahs.org Iha.netiha.comihahs.org

Folders (optional) Just like your computer, the server is divided into folders or directories. There may be many. There may be none.

File Name The name of the file to be viewed If no file is mentioned, the index.htm or default.htm is displayed. If index.htm or default.htm don’t exist, a listing of all files in the folder is sometimes displayed.

File names.html or.htm – hypertext markup language.asp – active server page File types that are associated with certain applications will automatically start that application or run within the browser. (.ppt,.jpg,.mp3, etc.) Go to ihahs.com. Download a form.

Cookies Cookies are small text files stored on the client computer by many websites. They contain info such as account name, preferences, etc. In general they are “good” files, saving you time. Look in c:\documents and settings\user\cookies (Win XP)

Miscellaneous URLs Open a browser Go to Yahoo. Click an article. Do a Google Search. Check your mail.