Number system
What is the number system ?
A number system is used to represent some quantity
why we use a number system ?
To give a number to something
To give a rank to something
To represent something
Types of number system
Decimal number system
Binary number system
Octal number system
Hexadecimal number system
Decimal number system
What is decimal number?
These are the numbers that starts from 0 to 9 it means these are 10
numbers
They have a base of 10
Decimal number system is mostly used around the world.
Octal number system
What is octal ?
Octal means 8
That is why octal number system has 8 values from 0 to 7
Its base is 8
For example
(568)8
Binary number system
Binary number is mostly used in computers
it has 2 values and that are 0 and 1
A collection of binary numbers are used to represent a large number
For example
(1010001111)2
Hexadecimal number system
This number system has 16 values starting from 0 to 9 and from A to
F
Its base is 16
For example
(abc)16
Conversions
Convert(10F)16 decimal ,binary ,and octal number system by direct
table and by calculation ?
Answer
In binary number
In octal number
In decimal number
OSI Model
A 7-Layer Communication Model
Point to
Ponder
What OSI stands for?
Open Systems Interconnection
By Whom?
ISO - International Organization for Standardization
Why?
To allow two systems to interconnect in spite of different
Architectures.
Example :
IBM and Apple Conflict
Point to
Ponder
What are its Advantages?
Divides the Communication Process into simple
processes.
Helps in Troubleshooting
Devices by Different Vendors can connect easily
Encourages industry to develop Compatible devices
Point to
Ponder
What are 7-Layers of ISO Model?
Application
Presentation
Session
Transport
Network
Data Link
Physical
Lets Consider them Briefly
Application Layer
Enables the user to access the network.
Provides user interface and supports for services such
as e-mail, file transfer, access to the World Wide Web.
Examples:
Chrome
Firefox
Outlook
Skype
Presentation
Layer
The presentation layer standardize all data into one
format
Like Data could be in PDF, JPEG, DOC, PNG, etc.
Convert into a Specific Code Like BCD, ASCII etc.
Performs Following functions
Data Reformatting
Encryption/Decoding
Compression/Decompression
Session Layer
Establishes, manages, and terminate user connection
Its Synchronous
Three Way Handshake
Decide Time Out of Connection
Example:
Banks Website etc.
Sensitive Data Website Like Nadra etc
Three Way Handshake
Transport Layer
Functions:
Segmentation
of data
Flow
Control
Error
Correction and retransmission of lost packets
Many
Protocols are used For Transmission
TCP
Transmission Control Protocol
UDP
Ultra Datagram Protocol
Session
Header
Data
Packet
Network Layer
Determines
the Destination IP Address
Determines
the Shortest Path to Destination
Adds
Header having IP addresses of Source and
Destination Server to Data Packet
This
is controlled by Routers.
What
is Router?
Arouteris
a networking device that forwards data packets
between computer networks.
Routersperform
Internet.
the traffic directing functions on the
SIP:
39.36.133.192
DIP:
129.36.133.192
Session
Header
Data
Packet
Data Link Layer
Offers a physical address so a devices data can be sent on the
network
It is responsible for node-to-node delivery of data.
It receives the data from network layer and creates FRAMES add
physical address to these frames and pass them to physical
layer.
It converts frames into bits before passing to physical layer.
Flow Control
MAC Address
It further divides into
LLC
MAC
Frame
S-MAC:
34:23:87:92:62:a1
D-MAC:
fc:3d:93:0e:54:a0
S-IP:
39.36.133.192
D-IP:
129.36.133.192
Session
Header
Data
Packet
Physical Layer
Deals with all aspects of physically moving data from one
computer to the next one.
Converts data from the upper layers into 1s and 0s for
transmission over media.
Defines how data is encoded onto the media used to transmit
the data.
Defined on this layer: Cable standards, wireless standards, and
fiber optic standards.
Copper wiring, fiber optic cable, radio frequencies, anything that
can be used to transmit data is defined on the Physical layer of
the OSI Model.
Physical topology (mesh, star, ring or bus).
Lets Have A Birds View of OSI Model
TCP/IP Suite
TCP/IP suite resides at Transport Layer of OSI Model
This protocol suite has been further classified into two
protocols
Transmission Control Protocol
User Datagram Protocol
In the above mentioned protocols, each has its own pros
and cons.
Transmission Control Protocol - TCP
TCP is a connection oriented protocol.
Reliable delivery of Data
Error Detection and Prevention
Retransmission of Damaged bits / Data
Acknowledgement
Segmentation
Sequencing
Reordering of Segments at other end
Relatively slow as compared to User Datagram Protocol
User Datagram Protocol - UDP
TCP is a connectionless service.
Does not establish link before sending data
Port Addresses
No Retransmission of Damaged bits / Data
No Acknowledgement
No Segmentation but fixed length data
Relatively very Fast as compared to Transmission Control
Protocol.
Used in Video Services Like
Youtube
Skype
