Protocol Example

8/4/2019 Protocol Example

1/22

Protocol Example

A quick word about protocols

because the Internet and everything itcontains is built on them


2/22

What is a protocol?

Protocol An agreement about how to do

something

This enables computers and software built by

different people to be able to communicate in thesame language

Examples that we have seen:

Hyper Text Transfer Protocol (HTTP) Web Browser

File Transfer Protocol (FTP) File transfer

Simple Mail Transfer Protocol (SMTP) Email

Internet Protocol (IP) Packets across the Internet


3/22

Contents!

Human Protocols

Sending a letter via the postal service

Shayne Evans5501 Sennott Sq.

Pittsburgh, PA. 15260

Kim Morrison

123 Somewhere St.

Someplace, PA. 15555


4/22

Computer Protocols

Sending a packet via the network

To: 192.168.1.1 on port 23

From: 192.168.1.110 on port 6710

Payload: The contents of the message belong

here.


5/22

Contents!!!

Visual Comparison

To: 192.168.1.1 on port 23

From: 192.168.1.110 on port 6710

Payload: The contents of the

message belong here.

Contents!

Shayne Evans5501 Sennott Sq.


Kim Morrison

123 Somewhere St.



6/22

Textual Comparison

The address of the letter is the destination

of the packet

The return address of the letter is thesource of the packet

The content of the envelope is the payload

of the packet

In both protocols, if you disobey the rules

your message will not be received


7/22

Protocol Layers

Protocols can be layered on top of other

protocols to enable new ways of

communicating


8/22

Example: Writing a letter

A common protocol that is followed when

writing a letter is:

[Date]

Dear [Recipient],

[Body of message goes here]

[Closing][Sender signature]

[Sender name]


9/22


A common protocol that is followed when

writing a letter is:

04/01/2008

Dear Kim,

Hey there!Whats up? Im good. Thanks.

Sincerely,Shayne EvansShayne Evans


10/22

04/01/2008

Dear Kim,

Hey there!Whats up? Im good. Thanks.

Sincerely,

Shayne EvansShayne Evans

Example: Writing a Letter

After following the protocol for writing a

letter, I can use the protocol for sending a

letter via the postal service:

Shayne Evans

5501 Sennott Sq.


Kim Morrison123 Somewhere St.



11/22


Thus, I have layered two protocols on top

of each other.

The lower protocol provides a service

used by the higher protocols.

LetterWriting Protocol

Sending a Letter via USPS Protocol


12/22

Protocol Layering:

The Internet is build this way Internet Protocol (IP) provides a way to

deliver packets to a destination

TCP

Internet Protocol

SSH, FTP, HTTP, SMTP

UDP

DNS, VoIP


13/22

TCP uses packets to maintain

connections across a network, and thus is

layered above IP

TCP

Internet Protocol


UDP

DNS, VoIP

Protocol Layering:

The Internet is build this way


14/22

UDPjust sends or receives raw packets

with a best-effort approach, also layered

above IP

TCP

Internet Protocol


UDP

DNS, VoIP

Protocol Layering:



15/22

SSH, FTP, HTTP, SMTP and many more

applications use TCP connections to

communicate data back and forth

TCP

Internet Protocol

SSH, FTP,HTTP,SMTP

UDP

DNS, VoIP

Protocol Layering:



16/22

DNS, VoIP, and many more applications

use UDP packets to communicate data

TCP

Internet Protocol


UDP

DNS, VoIP

Protocol Layering:



17/22

Summary of Internet/Networking

The Internet WWW + HTML

DNS

Clients/Servers and UNIXS SSH and telnet clients

FTP client

Networking Networks, Routers, and Packets

Connections Hostnames, IP addresses, ports

Protocols


18/22

Remaining Topics

PC Maintenance/Health

Disk cleanup, Scan disk, Defragging, Safe-

Mode, Browser cleanup, Backup

PC Safety

Protection against/Removal of

Malware: Viruses,Worms, Spyware, Adware

Identity theft: Phishing schemes, key loggers,trojan horses

University resources for protection


19/22

Plan for the course

04/07 PC Health, Teaching Survey

04/09 PC Health (proj7 assigned)

04/11 PC Health/Safety (hw7 assigned) 04/14 PC Safety

04/16 PC Safety (proj7 due)

04/18 In-class written final (hw7 due) 04/22 Make-up final from 8-9:50am


20/22

The Internet is built this way

The Internet Protocol is near the bottomlayer

It provides the rules for forming packets and

passing them to their destination

Above that are the TCP / UPD protocols

Above that are the HTTP/FTP/SSH/SMTPprotocols


21/22

Protocol Layers

Thus we have the following protocol

layers:

Postal Service Protocol

Reversing Messages Protocol

LetterW

riting Protocol


22/22

ComputerCommunication Protocol

Layers

Here are some common protocols found

on the Internet and how they are layered:

Internet Protocol

HTTP, FTP, IMAP, DNS

Protocols

TCP and UDP

Protocols

Application Layer

Transport Layer

Network Layer

[Hardware Stuff] Data link and Physical Layers

Documents

Protocol Example