CSE 561 Computer Networking Introduction

CSE 320 Internet Applications (2011) Internet Users 3.2B users worldwide 1.32 B in Asia Web 976 m – Number of websites (December 2011). 300 m – Added websites in B people used Facebook 1.39 B users in m users added in Youtube 1 T video playbacks 48 hours of video uploaded per min

CSE 320 Internet Statistics (2011) 3

CSE 320 Internet Statistics (2011) Source; 4

CSE 320 Source; Bangladesh Internet Statistics (2011) 5

CSE 320 Networks supporting the way we live. 6

CSE 320 Networks supporting the way we learn. 7

CSE 320 Networks supporting the way we learn. 8

CSE 320 Networks supporting the way we work. 9

CSE 320 Networks supporting the way we play. 10

CSE 320 Networks- Purpose??? Communication. 11

CSE 320 Elements of Communication 12

CSE 320 Elements of Communication What are the elements? 13

CSE 320 Devices (Sender/Receiver) These are used to communicate with one another Medium This is how the devices are connected together Messages Information that travels over the medium Rules Governs how messages flow across network Elements of Communication over Networks 14

CSE 320 Elements of Communication over Networks 15

CSE 320 Network Elements/Components Network Devices Hardware (Devices and Media) Software (Services and Processes) 16

CSE 320 Devices Two Types: End Devices Intermediary Devices 17

CSE 320 End Devices and their Role End devices form interface with human network & communications network 18

CSE 320 Provides connectivity between end devices. Manages data as it flows through the network. Examples? Switches Routers Intermediary devices 19

CSE 320 Intermediary devices Switch Router Hub Wireless Router 20

CSE 320 Software Services : provides information in response to a request. For example hosting services and web hosting services. Processes : Provide the functionality that directs and moves the messages through the network. Processes are less obvious to us but are critical to the operation of networks. 21

CSE 320 Processes and Services 22

CSE 320 Media 23

CSE 320 Network Media The channel over which a message travels 24

CSE 320 Messages- Data Representation Information today comes in different forms such as text, numbers, images, audio, and video. 25

CSE 320 Data Representation-Text Text : Different sets of bit patterns are designed to represent text symbols. Each set is called a code. ASCII American Standard Code for Information Interchange: 7-bit code/char, 1 bit for parity. Constitutes the first 127 characters in Unicode and known as basic latin. Unicode - 16 bit codes to represent a symbol. 26

CSE 320 Data Representation-Text 27

CSE 320 Text- Data Representation 28

CSE 320 Numbers : Directly converted in to binary which is base 2. The number 101 in base 2 is really Data Representation- Numbers 29

CSE 320 Images – Also represented by bit patterns. Mechanism different. Matrix of Pixels used. Each pixel is assigned to a bit pattern. Color images uses RGB or YCM methods. Data Representation 30

CSE 320 Audio- Continuous, not discrete. Converted to digital or analog signal. Data Representation 31

CSE 320 Rules - Protocols A set of predetermined rules that govern communication. Defines: What is communicated?? How it is communicated?? When it is communicated?? 32

CSE 320 Network Types PAN LAN MAN WAN 33

CSE 320 Personal Area Networks (PAN) A network that connects computers, peripherals and other devices within a personal operating space. Eg. Bluetooth 34

CSE 320 Local Area Networks (LAN) Connects computers, peripherals and other devices within a building (e.g. office, home) or in a limited area. Typical coverage 50 to 300 meters. Ex. Ethernet, Wireless LANs 35

CSE 320 Metropolitan Area Network (MAN) Is a city wide network. The coverage limitation is not strict, but real implementation may have range of up to 50 km in urban, suburban, or rural area. Ex. WiMax 36

CSE 320 Wide Area Networks (WANs) A network that spans larger geographical area. LANs separated by geographic distance are connected by a Wide Area Network (WAN) PSTN, Cellular Networks (GSM etc) 37

CSE 320 Internet The internet is defined as a global mesh of interconnected networks. Intranet ? 38

CSE 320 Internet 39

CSE 320 Internet 40 From Smart Computing: Tier 1 ISPs are large national or international ISPs. They are directly connected to the Internet backbone and can be considered part of the backbone itself. They have the highest speed connections and very reliable networks. Their customers are either lower-tiered ISPs or large companies that are looking for a very reliable and fast access to the Internet. A major advantage of purchasing service from a tier 1 ISP is if there is a problem with access, only one company is involved, so solving the problem is that much easier. Sprint is a tier 1 ISP. Tier 2 ISPs purchase their Internet service from a tier 1 ISP. Tier 2 ISPs tend to cover a specific region. They focus on business customers and have lower quality networks and slower access than tier 1 ISPs. Tier 3 ISPs also purchase their Internet service from tier 1 ISPs. Tier 3 ISPs tend to focus on the retail market, and they also tend to cover a specific region. Network quality and access speed are relatively low. Prices are much lower than for tier 2 or tier 1 ISPs."

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