ITGS

1. ITGS Types of network

2. WiMax • WiMax (Worldwide Interoperability for Microwave Access) • A wireless technology designed to transfer data over distances of up to 50 kilometres (31 miles) • Bandwidth = relatively high, but reduces with distance • Good for providing Internet access to homes in areas where lying cables would be difficult • Also good for providing hotspont access in large areas, such as cities

3. Wi-Fi • Wi-Fi (Wireless Fidelity) • A standard for wirelessly connecting devices in a relatively small area, such as an office • Wi-fi devices connect to a wireless router, then to the Internet • Common in laptop computers and mobile devices • Wireless hotspots - common in public restaurants and businesses • Bandwidth can be up to 108 Mbps. • Bluetooth • A wireless technology used only for short distance or PANs • Examples: headsets to music players, phones, game controllers to computers, etc.

4. 3G and 4G • 3rd generation and 4th generation • standards for wireless communication that operate using the mobile phone network • Used by smart phones and the modems in some laptop computers • Because they use the mobile phone network, 3G and 4G connections do not require the user to be near a Wi-Fi hotspot, making them good solutions for mobile Internet access • 4G is faster than 3G, but speed varies greatly depending on signal quality

5. Measuring Network Speed • Bandwidth - the amount of data a network can transfer at once • Narrowband - older, dialup network connections which have low speed • Broadband - more modern cable connections • Higher bandwidth connections are needed for tasks that involve large amounts of data transfer: • Video conferencing • VoIP calls • Quickly downloading large files • Network speeds are measured in bits per second (bps) • If your internet connection is 1 megabit per second, this is 128 kilobytes per second

6. Connection Speeds

7. Connection Speeds, pt. 2

8. Network Communication • In order to send and receive data on a computer network, you need a way to identify both the sender and receiver • MAC Address (also “hardware address”) • Media access control address - a unique number built into virtually every network device • Each MAC address is unique • They are stored in a device’s ROM, not designed to be changed • Sometimes wireless networks prevent access by unauthorized devices by filtering MAC addresses • Some computer users can change, or “spoof” their MAC address to get around this

9. Protocols • Protocol • A set of rules about how to do something. • Network communication couldn’t occur without networking protocols • Different protocols are used for different types of communication • IP (Internet Protocol) • Governs how devices on a network are identified and how information is routed between them • Used on many networks, not just the internet • On an IP network, each machine is assigned an IP address, which uniquely identifies it on that network • An IP address contains 4 groups of digits separated by dots (like 10.5.7.115) • You don’t want 2 devices to have the same IP address, so addresses are usually assigned by a DHCP (Dynamic Host Control) Server

10. IP Protocol, continued • With all of the computers in the world, it is impossible to have a unique IP Address for each one • Because of this, the IP protocol features private addresses - only used by computers on private networks such as LANs • Other computers on other networks can use the same private IP addresses • When a private network is connected to the Internet, the network gateway (the router) is assigned one public IP address which represents the entire network on the Internet

11. Assigning IP Addresses • Geolocation - since IP Addresses are assigned to ISPs by regions, then assigned to users by the ISPs, a record exists which can find a user’s location • All IP addresses are managed by the Internet Assigned Numbers Authority (IANA) • IANA assigns blocks of IP addresses to Regional Internet Registries (RIR), who manage IP addresses in different geographical regions • The RIRs assign addresses to Internet Service Providers (ISPs) • The ISP assigns you one of the IP addresses from its allocation • Dynamic IP address - changes each time you connect • Static IP address - remains the same each time you connect

12. TCP • Transmission Control Protocol - the other half of the most common network protocol, TCP/IP • TCP is a group of rules that govern how data is sent over a network • Ports • Identify the services available on networked computers • For example, when connecting to a web server to retrieve a web page, your computer will connect to port 80 because that is the standard port used by the HTTP protocol

13. The future of IP Addresses • IPv4, the current IP addressing system, uses 32 bit addresses • There are a total of around 4.3 billion possible IP addresses • According to the IANA, there were 150 million unassigned addresses remaining in 2010. • 243 million a year are being assigned • Soon, there will be no addresses for new users • IPv6 uses 128 bit addresses

14. The Internet • The Internet Backbone • The internet is a network of networks • Local networks are connected via Internet Service Providers (ISPs) • ISPs are connected to national Network Service Providers (NSPs) • NSPs are large companies that sell access to the Internet backbone • Internet backbone - the series of high speed links which connect major geographical areas • Backbone cables run under oceans and are usually high speed fiber optic cables • Backbones need to be high speed because of huge amounts of internet traffic • Everything from ‘below them’ on the internet travels through them • For example: Seacom backbone in Africa runs through the Indian Ocean and makes land in Mombasa, Kenya • From Mombasa, the connectivity filters down to the rest of Kenya

15. The Internet Backbone

16. Data Routing • When you send an email or access a web page, your data does not go directly to the recipient’s computer. • You don’t have a direct cable between your computer and every person’s computer that you are going to communicate with • Example: an email from El Paso to New York City • When the user clicks send, the data travels from his computer on the LAN to the ISP. • His ISP sends it to a National Service Provider, connected directly to the Internet Backbone. • An internet backbone lands at new York City, where the email travels from an NSP to the recipient’s ISP, then her computer. • Security: any of the systems that the data passes through can view or alter that data • So, don’t send sensitive info through email • When sen

17. Data Routing • Online shopping sites and banking systems always protect their users with SSL or TLS encryption to guard against electronic eavesdroppers. • Example of how the backbone can affect the world: • In early 2008, a ship performing work on the sea bed accidentally cut a primary backbone cab.e, affecting tens of millions of people in the Middle East and Asia. • Domain Names and DNS • URL (Universal Resource Locators) - are short enough to remember but provide enough details about the owner or content of the web site to be more memorable than IP addresses • Parts of a URL: • Domain name: kimhaefner.com • Top level domain: .com • Hostname: www.kimhaefner.com • File name: index.html • When sen

18. Domain Names • Top level domains: • Org - charities and non-profits • Mil - military sites • Edu- educational sites • Gov- governmental sites • Domain Name System (DNS) - a system responsible for translating domain names that people type into their web browser address bars into IP addresses that computers can use to locate each other. • DNS consists of servers connected to the Internet whose purpose is simply to map these domain names to IP addresses. • When sen

19. Internet Protocols • HyperText Transfer Protocol (HTTP) • The protocol that goeverns communication between web servers and web browsers • Every time you visit a web site, your browser is using http to communicate with the web server which hosts the site • HyperText Transfer Protocol Secure (https) • A version of the http protocol designed to encrypt data to provide communication secure from eavesdroppers • Essential for sensitive transactions such as sending passwords or bank account details • https uses Transport Layer Security (TLS) or Secure Socket Layer (SSL) encryption to achieve this security • A secure web connection is indicated by a https at the start of the address and a padlock icon • When sen

20. Synchronous or Asynchronous Transfer • Data transfer between computers can occur either synchronously or asynchronously • Asynchronous transfer - the sender and receiver are not synchronized in terms of time • Synchronous transfer - the sender and receiver synchronize times and agree on a transfer rate before the start of the transfer • They then transfer data at a fixed, regular intervals • This allows faster data transfer • The Internet or the Web? • The Internet is the physical network of computers across the globe, using the TCP/IP protocol to operate. • The World Wide Web is just one of the services that runs over the Internet, providing access to interlinked web pages containing text and images. • When sen

21. The Internet or the Web? • The Web uses the HTTP protocol • Many other services also run over the internet, each using their own protocols • Email uses Simple Mail Transfer Protocol (SMTP) • POP 3 (Post office Protocol)

22. The Internet or the Web? • What is Web 2.0? • Web 2.0 - web sites that allow users to contribute information as well as view it.