4. IPV4 Addressing System
IP Addressing
To uniquely identify each host connected in the internet, IP addressing
system is used.
An IPV4 address is a 32 bit binary address, implemented in a software
and universally defines hosts and routers in the Internet.
IP address is unique in the sense, no two hosts in the internet can have
same IP address at the same time.
IP address of a host is not fixed, it is also known as logical address.
Each network interface connected to the internet has a unique address
consisting of following two parts.
1. Network address: address of the network within the Internet
2. Host address: address of the computer within the network
5. Structure of IPV4 Address
IP Addressing
The 32-bit IP address is separated into four 8-bit octets, allowing each
octet to have a value ranging from 0 to 255.
Furthermore, the IP address is logically separated into two distinct
components i.e. Network ID and the Host ID.
The network ID is used to identify the subnet upon which the host
resides. The host ID is used to identify the host itself within the given
subnet.
IP addresses can be displayed in following two formats:
1. Binary Format: An example of binary notation is
11000000.10101000.00000001.01100100.
2. Decimal Format: An example of dotted-decimal notation is
192.168.1.100
7. Classes of IPV4 Addressing System
IP Addressing
Different networks have different sizes.
Basically, there are many small networks and few large networks.
To provide efficient use of 32-bit address space, IPv4 defined several
address classes and associated address formats as described below.
CLASS A : The first octet defines the network id, and the last
three octets define the host id.
Decimal value of first octet range from 1 to 126.
Total class A network possible is 126 with 16,777,214 hosts per
network.
Example of a Class A IP address: 64.32.254.100
Default Subnet Mask: 255.0.0.0
Application: Defense networks, Govt. security organizations
8. Classes of IPV4 Addressing System
IP Addressing
CLASS B : The initial two octets defines the network id, and
the last two octets define the host id.
Decimal value of first octet ranges from 128 to 191.
Total class B network possible is 16,384 with 65,534 hosts
per network.
Example of a Class B IP address: 152.41.12.195
Default Subnet Mask: 255.255.0.0
Application: Banks, MNC, Corporate Organizations
9. Classes of IPV4 Addressing System
IP Addressing
CLASS C : The initial three octets defines the network id,
and the last octet defines the host id.
Decimal value of first octet ranges from 192 to 223.
Total class C network possible is 2,097,152 with 254 hosts
per network.
Example of a Class C IP address: 207.79.233.6
Default Subnet Mask: 255.255.255.0
Application: Banks, MNC, Corporate Organizations
10. Special Classes
IP Addressing
CLASS D : Multi cast addresses.
Decimal value of first octet ranges from 224 to 239.
The IP address start from 224.0.0.0 to 239.255.255.255.
Application: Multi casting (One to many communications)
CLASS E : Reserved for future use.
Decimal value of first octet ranges from 240 to 255.
Application: Research purpose
13. Public Network
Public Network
Each Node connected in a public network directly
gets IP address from the ISP.
They can be accessed directly by any devices
connected in the internet.
14. Private Network
Private Network
Each Node connected in a private network does not directly get IP
address from the ISP, instead it is given IP address from the gateway
router.
Two devices belongs to two different private networks can not
communicate directly with each other, rather they communicate
through their respective gateway routers by Network Address
Translation technique.
16. Ranges of Private Addresses
Private Network
Private Addresses:- Three ranges of IP addresses as
private:
10.0.0.0 through 10.255.255.255
172.16.0.0 through 172.31.255.255
192.168.0.0 through 192.168.255.255
17. Network Address Translation
NAT
NAT is a method that enables hosts on private networks
to communicate with hosts on the Internet.
This technique has been used to convert the private
address to public address, the NAT allowing us to access
the internet and get services.
NAT is run on routers that connect private networks to
the public Internet, to replace the IP address-port pair of an
IP packet with another IP address-port pair.
It is required because of shortage of IPv4 Address.
25. Advantages and Disadvantages
Private Network
Advantages:
It improves security.
Maintenance and administration are simple.
Reconfiguration of the network is simple.
Disadvantages:
It complicates the communication process.
We are loosing 2 IP addresses per subnet.
26. Technical Specifications
Private Network
Borrowing bits from Host ID to form subnets is called sub-
netting.
If there are n bits in the Host ID and x bits are borrowed
from n bits, then
1) Number of subnets possible are 2^x
2) No. systems per subnets are (2^(n-x))-2