IP version 4 header format description:

Version:

It is a 4 bit field that indicate the version numbers to allow the evolution of IP protocol.

IHL:

IHL stands for internet header length, it may very from 20 to 60 bytes ,it is provide to inform the network about the length of the header.

Types of services(TOS) :

TOS field is 1 byte or 8 bit field, that helps the host to tell the subnet regarding it needs related to the type of services. It specify reliability, speed, throughput, delay etc.

Total length:

Includes the length of the header and data. That total length field indicates the total length of the datagram.

Identification:

It is a 16 bit field which allows the destination host to identify the datagram of current arrive arrived fragment.

Flag:

It is a 3 bit field, It contain 1 unused bit and two 1 bit field name DF and MF. DF stands for don’t fragment and is instructed to the router not to fragment the datagram.

MF stands for more fragment,is used to indicate that when all the fragment of datagram has been arrive successfully

Fragment offset:

It is a 13 bit field, It tells the position of the current fragment in the datagram.

Time to leave:

It is 8 bit field that specify the duration of a datagram can remain in the internet.

Protocol:

Protocol field tells the network layer that it should be given to which transport layer protocol the value of these field can be chosen from ICMP, IGMP, UDP, OSPF.

Header checksum:

It is a 16 bit field, that verify the header it detect the error that may occurs during transit.

Source address:

It is a 30 bit field, that indicate class type, network ID number, and host ID number.

Destination address:

It specify the IP address of the destination, hold the value of this field should also be remain unchange

Optional field:

It contains the other information about security routing times stamp. These are used for network testing and debugging