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 There are four octet in IPV4. Each octet has 8 bits. So, there are 32 bits in IPV4. IPV4 is based on binary (0, 1) and decimal (0 to 9).

       1st Octet                               2nd Octet                         3rd Octet                         4th Octet

        8 bits                                     8 bit                                  8 bits                           8 bits

27 26 25 24 23 22 21 20       27 26 25 24 23 22 21 20         27 26 25 24 23 22 21 20        27 26 25 24 23 22 21 20

  255.255.255.255                   255.255.255.255                255.255.255.255                 255.255.255.255

 

How to become 255.255.255.255 ? As each octet has 8 bit and is based on binary....

27 = 128,  26 = 64,  25 = 32, 24 = 16,  23 = 8,  22 = 4, 21 = 2,  20 = 1

128 + 64 + 32 + 16 + 8 + 4 + 2 + 1 = 255

 

Let's try to change from the Decimal to the Binary....

              

   Decmial                                                                            Binary

1st Octet     2nd Octet    3rd Octet   4th Octet                 1st Octet      2nd Octet     3rd Octet      4th Octet

192       .    168         .       1      .     0              =        11000000  . 10101000  . 00000001 .  00000000

223       .    200         .      100   .     25             =        11011111  .  11001000  . 01100100 . 00011001

172       .    16          .       31     .    87             =        10101100  .  00010000  . 00011111 .  01010111

 

Let's explore 192.168.1.0/24....

1st Octet                                2nd Octet                           3rd Octet                           4th Octet

        8 bits                                  8 bit                                 8 bits                                8 bits

27 26 25 24 23 22 21 20       27 26 25 24 23 22 21 20         27 26 25 24 23 22 21 20        27 26 25 24 23 22 21 20

  255.255.255.255               255.255.255.255                  255.255.255.255                 255.255.255.255

                                               Network                                                                        Host

 

Network Address = 192.168.1.0

Subnet Mask = 255.255.255.0

Usable IP Addresses = 192.168.1.1 to 192.168.1.254

Broadcast Address = 192.168.1.255

 

 

 Let's explore 192.168.1.0/25....

1st Octet                             2nd Octet                          3rd Octet                           4th Octet

        8 bits                                  8 bit                                 8 bits                                8 bits

27 26 25 24 23 22 21 20       27 26 25 24 23 22 21 20         27 26 25 24 23 22 21 20        27 26 25 24 23 22 21 20

  255.255.255.255               255.255.255.255                  255.255.255.255                 255.255.255.255

                                               Network                                                                        Host

 

1st Network Address = 192.168.1.0

Subnet Mask = 255.255.255.128

Usable IP Addresses = 192.168.1.1 to 192.168.1.126

Broadcast Address = 192.168.1.127

 

2nd Network Address = 192.168.1.128

Subnet Mask = 255.255.255.128

Usable IP Addresses = 192.168.1.129 to 192.168.1.254

Broadcast Address = 192.168.1.255

 

 

 Let's explore 192.168.1.0/26....

1st Octet                             2nd Octet                          3rd Octet                           4th Octet

        8 bits                                  8 bit                                 8 bits                                8 bits

27 26 25 24 23 22 21 20       27 26 25 24 23 22 21 20         27 26 25 24 23 22 21 20        27 26 25 24 23 22 21 20

  255.255.255.255               255.255.255.255                  255.255.255.255                 255.255.255.255

                                               Network                                                                        Host

 

1st Network Address = 192.168.1.0

Subnet Mask = 192.168.1.192

Usable IP Addresses = 192.168.1.1 to 192.168.1.62

Broadcast Address = 192.168.1.63

 

2nd Network Address = 192.168.1.64

Subnet Mask = 192.168.1.192

Usable IP Addresses = 192.168.1.65 to 192.168.1.126

Broadcast Address = 192.168.1.127

 

3rd Network Address = 192.168.1.128

Subnet Mask = 192.168.1.192

Usable IP Addresses = 192.168.1.129 to 192.168.1.190

Broadcast Address = 192.168.1.191

 

4th Network Address = 192.168.1.192

Subnet Mask = 192.168.1.192

Usable IP Addresses = 192.168.1.193 to 192.168.1.254

Broadcast Address = 192.168.1.255

 

(Note: The Subnet Mask is reverse proportional to host range. The larger the subnet mask, the smaller the host range.)

 

The following table is formula for Ipv4 addresses (Class C). I've made it when I was in Singapore Polytechnic.

 

Binary        Decimal       Prefix          Subnet Mask        Count of Networks   Usable Ip Range

    -              -                /24           255.255.255.0                 1                      254                 
 

27               128             /25           255.255.255.128              2                     126                 

                    +

26                64             /26           255.255.255.192              4                       62                   
                    +

25                32             /27           255.255.255.224              8                       30                   

                    +

24               16             /28            255.255.255.240             16                      14                            

                    +

23                8              /29            255.255.255.248             32                       6

                   +

22                4             /30             255.255.255.252             64                        2                       


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The networking devices need IP addresses to communicate with each other on the network. There are two types of IP addresses versions: IP Version 4 (IPv4) and IP Version 6 (IPv6).

IPv4 Address
              In IPv4 address, the host can communicate in one of three different ways:

Unicast: The process of sending a packet from one host to an individual host
 

Broadcast: The process of sending a packet from one host to all hosts in the network
 

Multicast: The process of sending a packet form one host to selected group of hosts


             

               In IPv4, the network range is defined by the followings:

Network address: A special network that refers to the network

Subnet Mask   The subnet mask is a 32-bit values used with IPv4 address that specifies the network portion of the address to the network device. The subnet mask uses 1s and 0s to indicate which bits of the IPv4 address are network bits and which bits are hosts bits.

Host address: The unicast address assigned to the end device in the network

Broadcast address: A special address used to send data to the all hosts in the network


For Example,

     Network             Network Address      Subnet Mask             Host Range                       Broadcast Address

192.168.1.0/24            192.168.1.0         255.255.255.0           192.168.1.1 to 254                192.168.1.255

192.168.2.0/25            192.168.2.0       255.255.255.128         192.168.2.1 to 126                192.168.2.127

 

IPv4 Network Classes

Address Classes       First Octet Range         Prefix and Mask            Number of Possible Networks         Number of Hosts

    A                              1 to 127             /8    255.0.0.0                       126                                   16,777,217  

    B                            128 to 191          /16   255.255.0.0                 16,382                                    65,534

    C                            192 to 223         /24   255.255.255.0            2,097,159                                    254

 
IPv4 Public and Private Addresses
                Although most IPv4 addresses are public addresses designated for use in networks that are accessible on the Internet, there are blocks of addresses used in network that are not accessible on the Internet. These addresses are called private addresses.


The private address blocks are:

Class A       10.0.0.0/8             (10.0.0.0 to 10.255.255.255)

Class B       172.16.0.0/12       (172.16.0.0 to 172.31.255.255)

Class C      192.168.0.0/16      (192.168.0.0 to 192.168.255.255)



Multicast Addresses       224.0.0.0/4 (224.0.0.0 to 239.255.255.255)
                The multicast transmission is designed to conserve the bandwidth of IPv4 network. It reduces the traffic by allowing a host to send a single packet to a selected set of hosts. To reach multiple destination hosts using unicast communication, a source host would need to send an individual packet addressed to each host. With multicast, the source host can send a single packet that can reach thousands of destination hosts.


Experimental Addresses    240.0.0.0/4 (240.0.0.0 to 255.255.255.254)
                 These addresses are reserved for future use. This suggests that they could be converted to usable addresses. Currently, these addresses are not usable in IPv4 network. However, these addresses are used for research.


 Default Route     0.0.0.0/8 (0.0.0.0 to 0.255.255.255).
                 The default route is “catch all” route to route packets when the specific route is not available.


Loopback Address           127.0.0.0/8 (127.0.0.0 to 127.255.255.255).
                 The loopback address is special address that hosts use to direct traffic to themselves.


Link-Local Addresses     169.254.0.0/16 (169.254.0.0 to 169.254.255.255)
                 These link-local addresses can be automatically assigned to the local host by the operating system in environment where no IP configuration is available.


Test-Net Addresses      192.0.2.0/24 (192.0.2.0 to 192.0.2.255)
                 The test-net-addresses are set aside for teaching and learning purpose.


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LAN (Local Area Network)
LAN is a computer network that interconnects computers within a limited area such as a residence, school, laboratory, university campus or office building and has its network equipment and interconnects locally managed.
 
WAN (Wide Area Network)
WAN is the network that is interconnected by two or more LANs. WAN is not only defined by a larger geographic distance, but also generally defined by leased telecommunication circuits.


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Network Protocols are machine languages used to communicate the devices on the network. For devices to communicate on a network, they must follow different protocols that perform the many tasks to be complicated. The protocols define the followings:

- The format of the message, such as how much data to put into each segment
- The way intermediary devices share information about the path to the destination
- The method to handle update messages between intermediary devices
- The process to initiate and terminate communications between hosts

The examples of Network Protocols are as follows:

Hypertext Transfer Protocol (HTTP):  HTTP is a common protocol that controls the way that a web server and web client interact.

Transport Protocol: Transmission Control Protocol (TCP) is the transport protocol that manages the individual conversions between a web server and web client. TCP divides the HTTP messages into smaller pieces, called segment, to be sent to the destination client. It also controls the size and rate of messages exchanged between the server and the client.

Internet Protocol (IP): IP takes the formatted segments from TCP, encapsulates them into packets, assign the appropriate addresses, and select the best path to the destination client.

Network Access Protocols: Network access protocols describe two primary functions: data-link management and the physical transmission of data on the media. Data-link management protocols take the packets from IP and format them to be transmitted over the media. The physical media controls how the signals are sent over the media and how they are interpreted by the receiving clients.


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OSI Model
                     The Open System Interconnection (OSI) Model provides an abstract description of the network communication process. International Organization for Standard (ISO) develops it to provide a road map for non-proprietary protocol development. The OSI model is just a reference model and many of OSI protocols are no longer in use. There are seven layers in OSI Model. Those are as follows:

Layer 7 -  Application
                        Performs services for the application used by the end users.

Layer 6 -  Presentation
                       Provides data format information to the application.

Layer 5 -  Session
                      Manages session between users.

Layer 4 -  Transport
                     Defines data segments and numbers them at the source, transfers the data, and reassembles the data at the destination.

Layer 3 -  Network
                    Creates and addresses packets for end-to-end delivery through intermediary devices in other network.

Layer 2 - Data Link
                    Creates and addresses frames for host-to-host delivery on the local LANs and between WAN devices.

Layer 1 - Physical
                    Transmits binary data over media between devices. Physical layer protocols define media specifications.

 
TCP/IP Model
                    TCP / IP is an open standard. The rules and implementation of the TCP/IP model were cooperatively developed by members of the industry using Request for Comments (RFC) documents. There are four layers in TCP/IP Model. Those are as follows:

Layer 4 -  Application
                   Represents application data to the user.

Layer 3 - Transport
                Supports communication between devices and performs error correction.

Layer 2 - Internet
                   Finds the best path through the network.

Layer 1 - Network access
                  Controls hardware devices and media.

 

Comparison of OSI and TCP / IP Model

  7.  Application     4. Application
  6.  Presentation
  5.  Session
  4.  Transport
   3. Transport
  3.  Network    2.  Internet
  2.  Data Link    1. Network Access
  1.  Physical

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Access Point
Normally, the access points allow the users to connect the Internet through the Wired Network(Switch, Router, Modem, etc....).

 
Switches
The switch (layer 2) normally receive the packets, process it and forward data to the destination.


Routers
Normally, the router is used to connect the different networks. But there are so many router functions if detailed.


Modem
The Modem is the common networking device that turns the digital data of an electronic device into modulated electrical signal for transmission over telephone lines and demodulated by another modem at the receiver side to recover the digital data.


Internet
The Internet is the global system of interconnected computer networks that use the Internet Protocol Suite (TCP/IP) to link billions of devices worldwide.


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Desktop Computer
A common computer used in a home or offices.

Laptop
A portable computer.

LAN Media
Local-area network media, usually copper cable.

Wireless Media
Depicts local-area network wireless access.

Switch
The most common devices for interconnecting local-area networks

Router
A device that helps direct message between networks

Firewall
A device that provides security of network.

Server
A common computer dedicated to provide application services to end users on a network. Server stores information to share with its clients.

Cloud
A group of networking devices out of local management control, often the Internet itself.


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