1 principles of computer organization basics of computer network tcp/ip: how messages get delivered...

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Principles of Computer Organization

Basics of Computer NetworkTCP/IP: How Messages Get Delivered Across the Internet

Dr. Greg ButlerComputer Science and Information Systems

School of Business AdministrationFort Lewis College

DescriptionThe purpose of this lesson is to explain the concept of a

protocol stack and the basic functions of TCP/IP by using a postal example. This lesson is aimed at middle school or high school students who do not have a background in network protocols

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Overview

PurposeThe purpose of this lesson is to explain the concept of a protocol stack and the basic

functions of TCP/IP by using a postal exampleLesson Objectives• Student will, when presented a scenario, identify which activities are accomplished by

IP, TCP, and upper level protocols.• Student will be use the correct vocabulary when discussing data communications

related to the protocol stack and TCP/IP.• Student will be able to describe the difference in how the physical address and the IP

address is used in moving traffic from one node to another on the internet.• Student will be able to use the Web as a tool to research networking topicsTarget Population• This lesson is aimed at middle school or high school students who do not have a

background in network protocolsDuration• 45 minutes with lab and exercisesSupplies and Equipment• Machine to display PowerPoint presentation.• PC with internet access for use in tracing internet traffic, ping, and running ipconfig.

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Communications ProtocolsOn step at a time

A communications protocol is a collection of all the steps required for two entities to communicate separated into logical layers.

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A Communications ProtocolA Letter to a Friend

When we communicate with a friend using the mail, we are using an informal communications protocol

We combine each of the layers into a stack.

Write letter

Place in envelope labeled with sender’s return address and the recipient’s address

Request mail receipt

Place in mailbox

Read letter

Recipient verifies the letter is addressed to him/her and checks to see who sent it

Return mail receipt

Retrieve from mailbox

Magical mail Transporter

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A Communications ProtocolA Letter to a Friend

When we communicate with a friend using the mail, we are using an informal communications protocol

We combine each of the layers into a stack.

Write letter



Place in mailbox

Read letter


Return mail receipt



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A Communications ProtocolEach layer has a “friend” at the other end

Layers in the sending stack have corresponding layers in the receiving stack.

Write letter



Place in mailbox

Read letter


Return mail receipt


If we write a letterIt must be read

If we put it in an envelope it must be removed


Two way communications only at this level

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Simplified Protocol StackOverview

• This is a simplified protocol stack, similar to the stack used in TCP/IP, the way most computers communicate across the internet.

• The purpose of this model is to get a general understanding of the purpose of a protocol stack. This will prepare us to explore the complexity of TCP/IP in depth.

Transport(TCP plus others)

InternetIP plus others

Network

Upper Level ProtocolsWord, Explorer,

HTTP, FTP

Windows

Write the letterRead the letter

Put the letter in an envelope, address it, and mail it

Post Office activities

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Simplified Protocol StackUpper Level Protocols



Network


HTTP, FTP

Windows

The various programs on our computer that:

• We use to create and save files, browse the Web, send email, etc.

• Interface these programs to the communications protocols as streams of data

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Simplified Protocol StackTransport Layer

Host-to-host communications that provide for • Communication between the sending

and receiving computers, regardless of the intermediate steps required to move the message

• An end-to-end handshake advising the sending host that the message was received

• Flow control to ensure that the recipient isn’t overwhelmed by incoming traffic

• Reassembling of incoming messages if they were broken up to make them small enough to transport



Network


HTTP, FTP

Windows

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A Communications ProtocolMoving the mail

• Mail is moved from address to address (physical locations).

• On the way between these addresses it will transit some intermediate nodes (such as our mail carrier’s van)

Magical Mail Transporter

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A Communications ProtocolInternet (Virtual Address) Layer


#32 Second Street Friendstown, NJ

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Simplified Protocol StackInternet Layer

Network to network communications

• Passes the message from

network to network toward its

destination

• Knows if it successfully passes

the message to the next

network

• Does not know if the message

goes any further



Network


HTTP, FTP

Windows

153.123.234.128

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A Communications ProtocolNetwork (Physical Device) Layer


I got the letter from the mailbox and put it in my truck

The letter was unloaded from the truck and put in the main post office.

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Simplified Protocol StackNetwork Layer

Node to node communications

• Passes the message to the next

hardware device in the path

• Actually “puts the signal on the wire”

• Knows if it successfully passes the

message to the next device

• Doesn’t know if the message goes

any further



Network


HTTP, FTP

Windows

00-04-23-8B-A3-8D

00-03-A4-7C-B3-AD

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Segment and Packet Wrappers

• AI– Show shell of TCP Segment and IP Packet wrappers and relate to parts of the

address on an envelope where reasonable

– Discuss the concept of a port as a requirement for complete addressing (analog-the recipient’s name)

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Tracing your connection

Use the tracert command to see the path traffic might take from your PC to a receiving host

1. Open the command prompt on your PCStart ->Programs ->Accessories -> Command Prompt

2. Enter the tracert command, using the domain name of a site that you visit frequently (such as Google) as the argument

tracert Google.com

3. The path is displayed in the command window.

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Finding a host IP address and tracing

1. Look up the ping command using the Web.Record its purpose and how to use it

2. Ping the site you used when you ran the tracertcommand

3. Record the IP address that replies.This is the IP address of the receiving host.

4. Run tracert, using the IP address as the argument instead of the domain name

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Finding your IP address and MAC Address

Use the ipconfig/all command to see the IP Address and MAC Address of the machine you are using

1. Open the command prompt on your PCStart ->Programs ->Accessories -> Command Prompt

2. Enter the ipconfig/all command ipconfig/all

3. Read off 1. Your IP Address

2. Your MAC Address(it is called the Physical Address in the results)

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Research Activity

Complete the following table, in your own words

Term Description How I would use it

tracert

ipconfig

ping

1 principles of computer organization basics of computer network tcp/ip: how messages get delivered...

Documents

middle school

high school students

protocol stack

basic functions of tcpip

internet access

tracing internet traffic

network protocols duration

overview purpose