IP

• The Internet Protocol (IP) is the principal communications protocol in the Internet protocol suite for Sending and receiving datagrams across network boundaries.
• Its routing function enables internetworking, and essentially establishes the Internet. IPv4 and IPv6 are the versions of IP.

• The below figure shows the functionality of each TCP/IP model layers.

Why IP

• The Internet Protocol is responsible for addressing hosts and for routing datagrams (packets) from a source host to a destination host across one or more IP networks.

Datagram construction

• Each datagram has two components: a header and a payload. The IP header is tagged with the source IP address, the destination IP address, and other meta-data needed to route and deliver the datagram.
• The payload is the data that is transported. This method of nesting the data payload in a packet with a header is called encapsulation.

IP address

• An Internet Protocol address (IP address) is a numerical label assigned to each device participating in a computer network that uses the Internet Protocol for communication.

IP address classes

• With an IPv4 IP address, there are five classes of available IP ranges: Class A, Class B, Class C, Class D and Class E, while only A, B, and C are commonly used.
• Each class allows for a range of valid IP addresses, shown in the following table.

Class	Address Range	Supports
Class A	1.0.0.1 to 126.255.255.254	Supports 16 million hosts on each of 127 networks.
Class B	128.1.0.1 to 191.255.255.254	Supports 65,000 hosts on each of 16,000 networks.
Class C	192.0.1.1 to 223.255.254.254	Supports 254 hosts on each of 2 million networks.
Class D	224.0.0.0 to 239.255.255.255	Reserved for multicast groups.
Class E	240.0.0.0 to 254.255.255.254	Reserved for future use, or Research and Development Purposes.

IPv4 vs IPv6

IPv4	IPv6
Developed in 1974 by IETF.	Developed by IETF in 1998.
Ipv4 address is 32 bit.	IPv6 address is 128 bit.
Has issue with IP address depletion, due to Address shortage.	Has sufficient address to cater the needs of future as well.
IPv4 header is 20 bytes	IPv6 header is 40 bytes
IPv4 header has 13 fields and is more complicated.	IPv6 header has 8 fields and is less complicated to IPv4.
No Built-in Security mechanism. IP sec is optional.	Has Built-in Security : Encryption and Authentication.
Less suitable for Mobile networks.	Better Suited for Mobile networks.
IPv4 is still widely used.	IPv6 is picking up but still behind IPv4.
Packet flow is not identified.	Uses the Flow Label to identify the Packet Flow.
Number of addresses : 232	Number of addresses : 2128
Example of an IPv4 :10.10.10.10	Example of IPv6 : FE80:0002:0000:0000:0102:A3EF:FE1F:8259