Transcript The Internet - The University of Tennessee at Martin

Intro to Computer Networks
Internet and Networking
Terms
Bob Bradley
The University of Tennessee at Martin
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.
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.
In 2001, there were over 100 Million computers
attached to the Internet.
In 2002, there are almost 200 Million computer and
nearly 800 Million Internet users.
Click here to see the real-time Internet growth charts
http://www.netsizer.com/
Intro to Computer Networks
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.
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.
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.
Intro to Computer Networks
Protocol
A design that specifies the details of how computers
interact, including the format of messages they
exchange and how errors are handled.
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.
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.
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)
Intro to Computer Networks
IETF & IESG
The official specification documents of the Internet
Protocol suite that are defined by the Internet
Engineering Task Force (IETF) and the Internet
Engineering Steering Group (IESG ) are recorded and
published as standards track RFCs. As a result, the
RFC publication process plays an important role in
the Internet standards process. RFCs must first be
published as Internet Drafts.
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 8bit decimal numbers separated by periods.
Example: www.utm.edu’s IP address is 208.47.4.80
Intro to Computer Networks
IPv4 (Internet Protocol Version 4)
The version of IP currently used in the Internet.
IPv4 uses 32-bit addresses
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
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)
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.
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:
To
From
208.47.4.80:80
10.11.1.115
Payload / Data
GET /index.html
Header
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
Packet 1
10.11.1.115
208.47.4.80
Part 1 of web page
Packet 2
10.11.1.115
208.47.4.80
Part 2 of web page
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
Intro to Computer Networks
Web Protocol and Language
HTTP – Hyper Text 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).
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.
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.
The University of Tennessee System has a state wide
WAN network connection it’s campuses.
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