Networks

QUME 185Introduction to Computer Applications

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Fundamental Concepts

Network: two or more computers, or other devices, connected together.

Connections: cables, wireless or other means.

Network communications follow rules: protocols

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Networks: large and small LAN, WAN, Internet, Intranet

LAN – Local Area Network WAN – Wide Area Network Internet (public) Intranet (private)

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Benefits of LANs and WANs

Increased efficiency and lowered costs sharing equipment (printers etc)

sharing of files and documents (group work)

sending messages (e-mail, conferencing)

sharing databases (access to customer lists, price and inventory information)

administering shared software

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Client/Server model

Most networks rely on the client/server model the client is the requesting program or

user (usually a personal computer)

the server is the computer that: manages network resources receives the request from client delivers the requested file (or other service) to

the client

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Servers

Servers can have many roles, and often serve multiple roles. They can be one or any of the following: File Server Print Server Database Server Web Server

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The Internet

The Internet is a group of networks linked together with routers in a way that allows any computer on any network to be able to communicate with another computer on any other network.

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The Internet

Corporate LANs and WANs also connect to the Internet

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Components & Protocols

Network Components: Transmit and receive data Conform to a common set of rules that enable

them to communicate with each other. These rules are called protocols

Network Protocols check to see if a connection is free to send data, and ensure that data do not collide on the network

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TCP/IP

These two protocols form the basis of Internet technology

Powerful and flexible Used on the Internet to enable data to

be sent from one computer to another across multiple networks

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IP – Internet Protocol

Each computer, or other device, attached to the Internet has an IP address that uniquely identifies it from the millions of other computers on the Internet

Typical format: 142.25.103.249 (This is the IP address for viu.ca)

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TCP – Transmission Control Protocol

Divides large data files into packets Each packet is transmitted separately Packets are reassembled at the

destination so that they are understandable as an e-mail message, Web page or other file type

Process is controlled by TCP

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Transmission process

Data packets are forwarded from one network gateway to another across the Internet

The packets don’t necessarily all take the same route

Therefore, may not arrive at their destination in the same order they were sent

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Keeping Track of Packets

Each packet carries: IP address of sender IP address of destination Where it belongs in the larger file

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Summary of TCP/IP

Simply stated, TCP/IP allows for the "handshake" that introduces distant and different computers to each other. ... TCP controls and keeps track of the flow of data packets, IP addresses and forwards individual packets. TCP/IP, which became the required protocol of ARPANET in 1983, also allowed ARPANET to expand into the Internet, facilitating features like remote login via Telnet --- and, later, the World Wide Web.

FROM: http://web.mit.edu/invent/iow/cerf.html Vinton Cerf – Developed TCP/IPhttp://www.ibiblio.org/pioneers/

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The World Wide Web

Just one application of the Internet Web pages are stored on servers

throughout the world The application software used to

access web pages is called a Browser (such as Firefox, Safari, Internet Explorer and Opera)

Web browser = Web client

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Some Web Acronyms

HTTP – Hypertext Transfer Protocol URL – Uniform Resource Locator – the

unique address of the web page http://www.viu.ca/index.aspprotocol | domain name | web page

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Corporate Intranets / Extranets

Organizations use TCP/IP networking protocols and web technology to create private, corporate networks Intranets – for use within the organization itself:

InVIU for example Extranets – for use by the organization and, for

example, its suppliers or customers

These networks use the same network infrastructure (hardware) as the LAN or WAN, but send the data using internet protocols.

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Networking – just the basics

Networking is a very complex topic

This was a very simple overview

Best to refer to networking specialists

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Class discussion exercise

What do you think are the basic computer skills that a person needs for 2012 and beyond?

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How a web server works on the Internet