The document provides an introduction to basic computer network concepts including the Internet, growth of the Internet, the World Wide Web, URLs, TCP/IP protocols, IP addresses, DNS, packets, email protocols, web protocols, Ethernet addressing, LANs, and WANs. Key points covered include how the Internet was created by ARPA, exponential growth over the past decades, how the Web uses HTTP and HTML, the purpose of URLs, how TCP/IP allows communication, IP address formats, how DNS translates names to addresses, how data is sent in packets, common email and web protocols, Ethernet addressing uses MAC addresses, characteristics of LANs and WANs, and that most standards are described in RFC documents.

1. Intro to Computer Networks
Basic Concepts of Networking

2. Intro to Computer Networks
The Internet
The global collection of connected networks that use
TCP/IP protocols.
The Internet was created from research done by the
U.S. Department of Defense Advanced Research
Projects Agency (ARPA) in the late 1960s – early
1970s.
The Internet became a commercial success in the
1990s.
No one group or country owns or “runs” the Internet,
because it is a collection of networks.

3. Intro to Computer Networks
Growth of the Internet
The Internet has experienced exponential growth
over two decades. It has been doubling in size every
nine to twelve months. (only recently has this
growth rate started to slow)
In 2001, there were over 100 Million computers attached to the
Internet.
In 2002, there were over 160 Million computer and nearly 800
Million Internet users.
In 2003, the number is approaching 200 Million computers.
Click here to see the real-time Internet growth charts http://www.netsizer.com/
(may not work)
See Internet growth at: http://www.isc.org/ds/

4. Intro to Computer Networks
World Wide Web
The hypermedia system used on the Internet in
which a page of information can contain text,
images, audio or video clips, and references to other
pages.
The main protocol of the Web is HTTP and the main
information format is HTML.
Information on the web is identified by a URL.
Invented by Dr. Tim Berners-Lee who donated his
work to the world for free!!!!
http://www.w3.org/People/Berners-Lee/Overview.html

5. Intro to Computer Networks
URL (Uniform Resource Locator)
A syntactic form used to identify a page of
information on the World Wide Web.
Example: http://www.utm.edu/~bbradley
Consists of a protocol :// hostname / page name
URLs are universal and unique. The URL to a page
can be used to identify and access it from anywhere
in the world on the Internet.
Can be on T-Shirts, on bill-boards, in magazines.

6. Intro to Computer Networks
TCP/IP
Transmission Control Protocol / Internet Protocol
The protocol suite used in the Internet.
Allows all the computers on the internet to
communicate with each other.
The common language of the Internet
A computer must be able to “speak” TCP/IP before it
can talk on the Internet.

7. Intro to Computer Networks
Protocol
Protocols are sets of rules.
What do you want to do? (Application)
Where are you going? (Addressing)
How do you get there? (Media types)
Did you get there? (Acknowledgments, Error
checking)

8. Intro to Computer Networks
Protocol Suite
A set of protocols that work together to provide a
seamless communication system. Each protocol
handles a subset of all possible details. The Internet
uses the TCP/IP protocol suite.
Includes: HTTP, SMTP, POP, IMAP, FTP.

9. Intro to Computer Networks
RFC (Requests For Comments)
Most of the Internet standards and protocols are fully
described in documents called RFCs.
See http://www.rfc-editor.org/
The Requests for Comments (RFC) document series
is a set of technical and organizational notes about
the Internet.
Memos in the RFC series discuss many aspects of
computer networking, including protocols,
procedures, programs, and concepts, as well as
meeting notes, opinions, and sometimes humor.

10. Intro to Computer Networks
Example RFCs
The following protocols are described by the
indicated RFC documents:
SMTP (RFC 821)
POP (RFC 1725)
IMAP (RFC 1730)
DNS (RFC 1034, RFC 1035)

11. Intro to Computer Networks
IP Address
A 32-bit address assigned to a computer that uses
the TCP/IP protocols. The sender must know the IP
address of the destination computer before sending a
packet.
This is like a phone number for the computer.
A program on one computer communicates with a
program on another computer, by connecting to its
IP address.
The 32-bit address is usually represented as four 8-
bit decimal numbers separated by periods.
Example: www.utm.edu’s IP address is 208.47.4.80

12. Intro to Computer Networks
IPv4 (Internet Protocol Version 4)
The version of IP currently used in the Internet.
IPv4 uses 32-bit addresses

13. Intro to Computer Networks
Dotted Decimal Notation
The syntactic notation used to express a 32-bit IPv4
address.
Each octet is written in decimal with a period
separating octets.
Example:
Mars.utm.edu’s IP address is 208.47.10.107
www.utm.edu’s IP address is 208.47.4.80
www.yahoo.com’s IP addresses are
64.58.76.229, 64.58.76.179, 64.58.76.177,
64.58.76.176, 64.58.76.223, 64.58.76.227,
64.58.76.225, 64.58.76.178, 64.58.76.224

14. Intro to Computer Networks
IP Numbers
Four groups of 8 bit numbers.
Each 8 bit range has 256 possibilities:
00000000 = 0
11111111 = 255
Therefore IP’s range from
0.0.0.0 to 255.255.255.255
There are about 4 billion possible addresses.
However, there are several reserved ranges.

15. Intro to Computer Networks
DNS (Domain Name System)
The automated system used to translate computer
names into equivalent IP addresses.
A DNS server responds to a query by looking up the
name and returning the address.
DNS is a global distributed database.
If you tell your web browser to connect to
www.utm.edu, the web browser will use the DNS
system to convert the host name (www.utm.edu)
into an IP address (208.47.4.80)

16. Intro to Computer Networks
Packet
A small, self-contained parcel of data sent across a
computer network.
Each packet contains a header that identifies the
sender and recipient, and a payload area that
contains the data being sent.
All messages sent on a network such as the Internet
are broken into small chucks called packets.

17. Intro to Computer Networks
Packets
For example, if I download a web page, my web browser sends
a message in a packet like this to the web server:
When the web server receives this request, it will send the web
page back to my computer by breaking it down into smaller
parts and sending each part in a packet:
To From Payload / Data
208.47.4.80:80 10.11.1.115 GET /index.html
Part 1 of web page
Part 2 of web page
Header
10.11.1.115 208.47.4.80
10.11.1.115 208.47.4.80
To From Payload / Data
Packet 1
Packet 2

18. Intro to Computer Networks
E-Mail Protocols
SMTP – Simple Mail Transfer Protocol
Used to transfer e-mail from one computer to
another across the Internet.
SMTP is part of the TCP/IP protocol suite.
POP3 – Post Office Protocol
A simple protocol used by a email client program
to download mail from a server.
IMAP - Internet Message Access Protocol
A more complicated protocol used by some email
clients to download and manage email

19. Intro to Computer Networks
Web Protocol and Language
HTTP – Hyper Text Transfer Protocol
The simple protocol used to transfer a World Wide Web
page from one computer to another.
A web client opens up a connection to a web server and
sends GET PAGENAME and then the web server sends back
the page text (usually HTML) over the connection.
HTML – Hyper Text Markup Language
The source form used for documents on the World Wide
Web. HTML embeds commands that determine formatting
along with the text to be displayed (e.g., to move to a new
line or indent text).

20. Intro to Computer Networks
Ethernet: Addressing
Since there can be many users on an ethernet network, everyone
has to have their own unique address.
This is called the Media Access Control (or MAC) address, or
sometimes ethernet address, physical address, adaptor address,
hardware addres, etc.
It’s a 12-digit (48 bit) hexadecimal address that is unique to that
ethernet adaptor and no other in the world. It can be written as
00:30:65:83:fc:0a or 0030.6583.fc0a or 003065:83fc0a or 00-30-
65-83-fc-0a but they all mean the same thing.
The first 6 digits are the Vendor code, (003065 belongs to Apple),
the last 6 are the individual inteface’s own. Like a car’s VIN. See
http://coffer.com/mac_find/ to look up some vendor codes.

21. Intro to Computer Networks
LAN (Local Area Network)
A network that uses technology designed to span a
small geographic area. For example, an Ethernet is
a LAN technology suitable for use in a single building.
LAN’s can be “bridged” together to allow multiple
buildings to be on the same LAN, but a LAN cannot
span for much more than a few thousand feet.
The University of Tennessee at Martin has a LAN that
connects all of the computers on its campus.
LAN’s have lower propagation delay than WANs.

22. Intro to Computer Networks
LAN
Hub
Computers
A LAN can consist of computers in the
same room or building that are hooked
together using a Hub/Switch type
device.

23. Intro to Computer Networks
LAN
Hub
Computers
Hub
Computers
Hub
A LAN can also allow
Computers on different floors or
even different buildings to be
bridged together.

24. Intro to Computer Networks
LAN
Hub
Computers
File
Server
Hub
Computers
Hub
A LAN can allow computers to
share resources such as printers,
disks or Internet connections. Internet
Gateway
Printer
Interne
t

25. Intro to Computer Networks
WAN (Wide Area Network)
A network that uses technology designed to span a
large geographic area. For example, a satellite
network is a WAN because a satellite can relay
communication across an entire continent. WANs
have higher propagation delay than LANs.

26. Intro to Computer Networks
Reference
Slides created by Bob Bradley, The University of
Tennessee at Martin
Most of these terms were taken from the Glossary of
Networking Terms and Abbreviations in the back of
the book Computer Networks and Internets with
Internet Applications Third Edition, Douglas E. Comer
Comments and notes added by Bob Bradley, The
University of Tennessee at Martin