Packets

1
Packets

• Which of the following statements is NOT true. A
  typical packet on the Internet
• can become lost and never find its destination
• can be returned to the sender
• has a limited time to reach its destination
• can be routed through different routers than the
  rest of a file or message
• contains the address of the sender and the
  receiver

2
Networks Telecommunication
3
Learning Objectives
Any sufficiently advanced technology is
indistinguishable from magic. Arthur C. Clarke

• At the end of this class, you will be able to
• List the basic components of a network
• Diagram how ADSL and cable modems work
• Describe and list the basic component of Wireless
  networks
• Analyze the advantages that networks can provide

4
Connecting to the Internet

• Internet Service Provider (ISP)

5
Physical Media for Networks

• Networks are built on physical media.
• Twisted pair (Category 5)
• Twisted pair (Traditional)
• Coaxial Cable
• Fiber optic
• Wireless/infrared
• Wireless/radio

Never in history has distance meant less. Alvin
Toffler
6
How a Modem Works
The word modem comes from theterms modulation
and demodulation
Modulation
Demodulation
7
ADSL How it Works
Copper wirePOTSDigital data
To work properly the ADSL modem must be located
within a certain distance from the phone
companys answering ADSL modem.
8
Cable ModemHow it Works
EtherNet Card
9
The Network Interface

• A Network Interface Card (NIC)
• Is needed to connect directly to a network
• Can add an additional port to the computer
• Controls the flow of data between the RAM and
  the network cable
• Converts the computers digital signals into the
  type required for the particular network

10
ISP

• provides access to the internet
• Examples
• Shaw - Cable Internet
• Telus ADSL Internet
• often provide services, such as email

11
Client/Server Model
Server
Client software sends requests from the user to
the server
Client
Server software responds to client requests by
providing data
12
How does email work?

• We saw yesterday how messages are divided up when
  they are sent
• But where is the mailbox actually kept?
• They are kept on a server
• We tell our email client (application) where to
  look for our messages
• Example email clients
• Microsoft Outlook
• Microsoft Outlook Express
• Mozilla Thunderbird

13
Accessing Email
Incoming mail (i.e. mail sent to us)
Outgoing mail (i.e. mail we send)
14
Sending and Receiving Email
15
How does email work?

• When you set up your email client, it will ask
  you for information about the servers to use.
• What is your incoming server?
• What is your outgoing server?

16
Whats with all the protocols?

• POP (Post Office Protocol) e.g. pop.uvic.ca
• messages downloaded to computer, not kept on
  server
• once downloaded, can only be viewed on that
  computer, but you dont need access to the
  Internet to read them
• IMAP (Internet Messaging Access Protocol) -
  imap.uvic.ca
• messages kept on server
• messages accessible anywhere, but requires
  Internet connection
• SMTP (Simple Mail Transfer Protocol) e.g.
  smtp.uvic.ca
• common protocol for sending email

17
Online email
With online email, this process still
exists. However, since youre viewing them in a
web browser and not downloading them, these
details are hidden from you.
18
Networks

• Its all about communication!
• Linking computers to send messages
• Sending emails
• Transferring files
• Viewing webpages
• Transmitting information across a network.

19
Basic Network Anatomy

• A computer network is anycomputer system that
  linkstwo or more computers
• There are three essentialcomponents in a
  network
• Hardware
• Software
• People

20
Linking Up Network Basics
Why is networking important?

• Cost
• allows people to share hardware
• Efficiency Productivity
• allows people to share data and software
• Opportunity
• allows people to work together in ways that are
  otherwise difficult or impossible

21
LAN (Local Area Network)

• A LAN is a network in which the computers are
  physically close to each other

• They typically share peripherals (printers and
  servers)
• Each computer and shared peripheral is a node on
  the LAN

22
Networks

• Examples
• Home network linking computers
• Wireless networks
• Global Positioning System (GPS)

23
WAN (Wide Area Network)

• WANs are often made up of LANs

24
Fiber Optic Cables

• Fiber optic cables are replacing aging copper
  lines
• They use light waves to carry information
• They provide data rates over one billion bits per
  second
• They offer extremely low error rates

25
Peer-to-Peer Model

• The peer-to-peer model allows every computer on
  the network to be both client and server
• Peer-to-peer networking is built into some
  operating systems
• Many networks use a hybrid of client/server and
  peer-to-peer

26
Fiber Optic Cables

• Fiber optic cables are replacing aging copper
  lines
• They use light waves to carry information
• They provide data rates over one billion bits per
  second
• They offer extremely low error rates

27
Building Bandwidth

• The quality of information transmitted through a
  communication medium depends upon bandwidth.
• Increased bandwidth means faster transmission
  speed
• Bandwidth is affected by the amount of network
  traffic, software protocols, and type of network
  connection

28
Wireless network
29

• In a computer network setting, which of the
  following correctly defines a protocol
• An agreed-upon format for transmitting data
  between two devices. Protocol determines error
  checking methods, data compression, how the
  sending device will indicate it has finished
  sending, how the receiving device will indicate
  it has received a message.
• An agreed-upon format for a device to transmit
  data. Protocol determines error checking methods,
  data compression, how the device will indicate it
  has either sent or received a message.
• A network operating system (NOS) format for
  transmitting data between the client and the
  server. Protocol determines error checking
  methods, data compression, how the server will
  indicate it has finished sending, how client will
  indicate it has received a message.