About IP Address

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 hos

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.