In this lesson we will Examine the difference between the Internet the Web and the Intranet Cover packet switching and how the Internet enables the Web Starter Activity What do you do online ID: 651573
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Slide1
The Structure of the InternetSlide2
In this lesson we will…
Examine the difference between the Internet, the Web and the Intranet.
Cover packet switching and how the Internet enables the Web.Slide3
Starter Activity
What do you do online?
OMG
How would you feel if you couldn’t do any of this?
How would you cope? Slide4
Internet
Web
Intranet
The Internet houses the Web but why does the intranet overlap both?
How do these intercept?
What are their functions?
The Internet, the Web and the IntranetSlide5
Activity 1
Now we are going to fill in the gaps …Slide6
The Internet
This
is a
global system of networks which are connected together using a particular protocol called the
TCP/IP . This is a procedure which controls how computers send information to each other. One important feature of this system is its decentralised structure. Because there is no central point on which communications depend, the system can continue to
function
well even when some
connections
break down. Slide7
The World Wide Web
This application, which was created in 1989, sits on top of the
Internet
. It contains information resources in many forms (
documents written in HTML, images, music, video, etc.) which can be
linked
together. Users
can access information via a
browser
(which helps them find information, entertainment or services), or navigate between documents by clicking on
hyperlinks
.
Each information resource has a unique
URL
and these resources can be transferred using another protocol called
HTTP
.Slide8
Intranet
Many companies want to take advantage of the
networking
capabilities of computers, but also need to keep their information
restricted and secure. For this reason they often use a internal network to help them
communicate
, share information, provide computing services, or create
internal
websites. Employees of organisations can access the information in these systems, but
external
access is controlled or blocked.Slide9
The Internet…
The Resilience of the InternetSlide10
Communication and the Internet…
Protocols: Set of rules for communication
Transmission Control Protocol (TCP) and Internet Protocol (IP): Protocols for communicating across the InternetSlide11
TCP and IP
TCP: underlying layer of the Internet ensuring delivery of information
IP: Responsible for providing addresses for sending informationSlide12
IP Packets
Items that are transferred across the networks
IP Packet:
Header Actual Data
Source IP Address,
Destination IP Address,
Packet Number,
Number of packets that make up that itemSlide13
Foundations of communicating across the Internet:
Protocol are a set of rules
TCP: delivering the information
IP: Providing the addressesInformation is broken into IP PacketsQuestions?
So far…Slide14
Now to get your brains working that little bit more….Slide15
Post Office Analogy
When you send a Letter in the Post what is the process…Slide16
Digital Post Office
Write the Letter
Sign the Letter
Put it in an envelopeWrite the Address of Destination on Envelope
Place a Stamp on the EnvelopePlace Letter in Post BoxLocal Post Man picks up letter amongst others from post boxLetter goes through Sorting OfficeNew local Post Man delivers letter to destinationSlide17
Activity 2
Together, organise the slips which represent the steps for packet switching into the correct order – think about the post office analogy to help you
Slide18
Packet Switch Networks - 1
Moving a File from A to BSlide19
Packet Switching
Point A
Point BSlide20
Now Lets Give it a Go….Slide21
Packet Switching
Point A
Point BSlide22
Packet Switch Networks -
2
Routing around missing serversSlide23
Packet Switching
Point A
Point BSlide24
Packet Switch Networks -
3
Packet orderSlide25
Packet Switching
Point A
Point B
HE
LL
OSlide26
Packet Switch Networks -
4
Time-To-Live (TTL)Slide27
Packet Time To Leave (TTL)
Data packets have TTL number
TTL is number of server-to-server hops before the packet is no longer forwarded (hop limit).
A server receiving a packet reduces TTL by 1 before passing it on.A server receiving a packet with TTL discards it and sends a re-send message to the originating server (i.e. send packet again)Slide28
Point A
Point B
HE
LL
O
10
9
8
7
6
9
9
5
4
3
2
1
8
7
6
5
4
3
8
7
6
5
4
3
2
1
Packet Switching
0
Request new packet
9
8
7
6
5
4
3
10Slide29
IP Address
A
unique label assigned to each device in a computer network that uses the Internet Protocol. Does anyone know what is the most common form of IP Address and what is the newer IP Address? Slide30
IPv4
Most common Internet Protocol
Limited number of IP addresses
IPv6 – newer version (to be discussed at a later date)Slide31
IPv4
32-bits (4 bytes)
= 2
^32 different values (this is binary which will cover at a later date)Slide32
Bits/Bytes
If 32 bits = 4 bytes, so how many
bits
are there in 1 byte?Slide33
Fun Fact…
Half a Byte (4 bits) is called a Nibble!Slide34
IP Addresses
0 to 255
0 to 255
0 to 255
0 to 255
192 192 158 158
1 chunk
1 byte
1 chunk
1 byte
1 chunk
1 byte
1 chunk
1 byteSlide35
IP Addresses
192 192 158 158
Network Identifier
Host
IdentifierSlide36
IP Addresses
Are these IP addresses on the same network?
1) 126.203.123.123
and 126.203.100.100
2) 126.203.123.123 and 123.123.126.203 3)
126.203.97.54 and 126.203.123.123 Slide37
IP Addresses
Are these IP addresses on the same network?
1) 126.203.123.123
and 126.203.100.100 - YES
2) 126.203.123.123 and 123.123.126.203 - NO 3)
126.203.97.54 and 126.203.123.123 - YES Slide38
Summarise…
Can you individually write 4 or 5 points that you have learnt and can take away with you today…Slide39
Internet is the foundation
Web uses the Internet
Intranets are private networks
Communicating across the Internet:Protocol are a set of rulesTCP: delivering the informationIP: Providing the addresses
Information is broken into IP PacketsMethodology used for communicating IP Packets across the Internet is called Packet Switching
To Summarise…Slide40
To Summarise…
IP Addresses are used to identify a device on a network
IPv4 is most commonly used IP Address
IP Addresses are made up of 4 chunks, 32-bitsFirst 2 Chunks = Network IdentifierSecond 2 Chunks = Host Identifier
*Key Terms HandoutSlide41
Any Questions?