Intro to Computer Networks Internet and Networking Terms Bob Bradley The University of Tennessee at...

Intro to Computer Networks

Internet and Networking Terms

Bob BradleyThe University of Tennessee at Martin


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.


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/


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.


URL (Uniform Resource Locator)

A syntactic form used to identify a page of information on the World Wide Web.

Example: http://www.utm.edu/~bbradleyConsists 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.


TCP/IP

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


Protocol

A design that specifies the details of how computers interact, including the format of messages they exchange and how errors are handled.


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.


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.


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)


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.


IP AddressA 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


IPv4 (Internet Protocol Version 4)

The version of IP currently used in the Internet.IPv4 uses 32-bit addresses


Dotted Decimal NotationThe 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 208.47.10.107www.utm.edu’s IP address is 208.47.4.80www.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


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)


PacketA 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.


PacketsFor 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


E-Mail ProtocolsSMTP – 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 ProtocolA simple protocol used by a email client program to download mail from a server.

IMAP - Internet Message Access ProtocolA more complicated protocol used by some email clients to download and manage email


Web Protocol and LanguageHTTP – 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 LanguageThe 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).


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.


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.


Reference

Slides created by Bob Bradley, The University of Tennessee at MartinMost 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. ComerComments and notes added by Bob Bradley, The University of Tennessee at Martin

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