Communication software and
protocols
Sara Tang 5D (35)
Oh?what on earth is
communication software?
• The application used to transmit digital
messages from one user to another through
a computer network.
Services provided by
communication software
• Broadcasting messages e.g. online forum
• Data/information sharing e.g. chat rooms
• Real-time communcation e.g. MSN
Type of communication
Type of
communication
Type of message
transmitted
Communication
Software required
Example of
communication
software
Email
Text message and
attached files
E-mail client
application,web
browser
E-mail client
application:micr
osoft outlook
Web browser:
yahoo! mail
Video conferencing
Real-time streamed
video message
Video conferencing
software
iVisit
Internet phone
Real-time streamed
audio message
Internet phone client Skype
application
Instant messaging
Instant text
message,audio and
video message and
digital files
Instant messageing
software
Window Live
Messenger
Chat room
One to many instant
text message
Web browser
Firefox
Type of communication
MSN
iVisit
Skype
Why communication software?
•
•
•
•
Fast transmission speed
Low transmission cost
Support mulitimedia message
Transmitted information is mostly reusable
What are communication
protocols?hmmm…
• a set of rules about data formatting or
signalling that is understood by all the
communication devices
=>a common standard understood by all
communication devices in a computer
network
• to transmit a network application’s data
over a computer network
• Used by communication software to work
with communication devices.
Application of common
communication protocols
Communication protocol
application
Transmission Control
Protocol/Internet Protocol
(TCP/IP)
Internet access,network
communication in an internet
Simple Mail Transfer
Protocol(SMTP)
Transferring e-mail messages
Wireless Application Protocol
(WAP)
Wireless communication for
handheld devices such as
iphone
Internet Fax Protocol (IFP)
Sending and receiving faxes
over the internet
Voice Over Internet Protocol
(VoIP)
Voice data transmission by
internet phone communication
software
Communication protocol
application
hypertext transmission protocol (HTTP) By using the linkage of hypertext to
transfer information in the world wide
web or intranet
File Transfer Protocol (FTP)
copying a file from one host to another
over a TCP-based network, such as the
Internet
Internet Message Protocol
(IMAP)
allowing e-mail client to access e-mail
on a remote mail server.
Post Office Protocol - Version (POP3)
Retrieving e-mail from a remote server
over a TCP/IP connection
POP3 is supported by most webmail
services such as Hotmail, Gmail and
Yahoo! Mail.
Secure Shell (SSH)
-allows data to be exchanged using a
secure channel between two networked
devices .
-Implemented in some webpages
e.g.bank transaction website
Open system interconnection
(OSI)model
• When data is transmitted from one
computer to another ,the data must go
through the OSI model
• It is a way of sub-dividing a communication
into smaller parts called layers.
• a layer provides services to the layer above
it and receives services from the layer
below it.
The 7 layers
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•
•
•
•
•
•
Application layer
Presentation layer
Session layer
Transport layer
Network layer
Data link layer
Physical Layer
Application layer
• Provides interface for application software
to set up communication with another
application software
Presentation layer
• Converts data into a format that can be
understood by the receiver’s system
Session layer
• sets up and maintains the communication
linkages between two computers during
data transmission
• It establishes, manages and terminates the
connections between the local and remote
application.
Transport layer
• transfer of data between end users
Transport header (TH) +data =datagram
• TH contains the transportation information
eg. The protocol used
• Datagram transmitted over the internet
using TCP will be divided into smaller
packets before transmitting to the next layer
• Data is sent in packets
-allows a path to be shared among users in a
computer network.
-avoids repeatedly sending large files
-when a packet is corrupted or missing during
transmission,only the corrupted packet
instead of the whole data file will be resent.
Network layer
• Determines the routing and forwarding of
data.
• Network Header +datagram=packet
-NH contains network address information
eg.IP address
Data link layer
• For network addressing ,error detection and
correction
• Data link header+Packet+Data link
trailer=frame
Physical layer
• Transfers frames physically on a LAN
• defines the relationship between a device
and a transmission medium
eg.copper or optical cable
An overview about OSI model
Application layer
eg. Using Microsoft outlook to send an
email to Florence
Provides interface for application
software to set up communication with
another application software
Presentation layer
Converts data into a format that can be
Eg Convertion of my commands to the understood by the receiver’s system
format that is compatible to florence’s
system.
Session layer
eg setting up the linkage between my
computer to my mail server to
florence’s mail server to her device.
It establishes, manages and terminates
the connections between the local and
remote application.
Transport layer
Eg A TH is added to the email and
becomes a datagram for transfer.
transfer of data between end users
Network layer
eg. A NH is added to datagram and
forms a packet.my email has found the
route to florence’s place.
Determines the routing and forwarding
of data.
Data link layer
Eg,errors of the data are detected and
corrected. A frame is formed
Responsible for the network addressing
as well error detection and correction.
Physical layer
e.g. The transfer of the frames from the
wan to florence’s lan to her device.
Transfers frames physically on a Lan