Transcript Course overview

IP packets and addresses
Skills: none
Concepts: data and program files, IP packet, packet
header, packet body, IP address, host name
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Where does this topic fit?
• Internet concepts
– Applications
– Technology (communication)
– Implications
• Internet skills
– Application development
– Content creation
– User skills
Internet protocol (IP) packets
10011
00110
11101
121.115.14.3
10101
155.135.1.1
Two parts of an Internet protocol (IP) data packet
Header
To: <IP address>
From: <IP address>
(and more)
Body
A portion of a Web page, video stream, image, etc.
Comparing an envelope with a packet
What do you write on the front of an envelope?
Is the packet header like the envelope or its contents?
Break the file into packets
↓
0101010111001010100111001010101010101001
0101010101010101011001010100101010101001
↓
Header1
Header2
Header3
Header4
|
|
|
|
01010101110010101001
11001010101010101001
01010101010101010110
01010100101010101001
Internet protocol (IP) packets
H1 | Body
H4 | Body
H2 | Body
H3 | Body
121.115.14.3
155.135.1.1
Re-assemble the image
Header1
Header2
Header3
Header4
|
|
|
|
01010101110010101001
11001010101010101001
01010101010101010110
01010100101010101001
↓
0101010111001010100111001010101010101001
0101010101010101011001010100101010101001
↓
IP addresses and domain names
155.135.55.165 = www.csufh.com
http://155.135.55.165/
http://www.csudh.edu
What happens if you enter the URLs shown above?
Why does it display a page when you only specified the domain
name of the Web server and no file name like larry.html?
Summary
100110
101010
011101
100101
Self-study questions
1.
2.
3.
4.
An IP packet consists of two parts, what are they?
An IP header has several fields, three of them are __, __, and __.
What is the difference between an IP address and a host name?
What is the difference between an IP address and a URL? Why do
we need both?
5. Is there any difference between an image and a copy made on a
computer that retrieves it? Explain.
6. Why do you think the overall packet length limit of 65,535 bytes is
such an odd number?
7. Is a receiving computer able to display any image it receives?
Explain your answer.