Networking - Explain the concepts and capabilities of IP Datagram

Explain the concepts and capabilities of IP Datagram.

Data transmitted over an internet using IP is carried in messages called IP datagrams. 
Like all network protocol messages, IP uses a specific format for its datagrams.

The IPv4 consists of the following fields:

1. Version: the version of IP used to generate the datagram. For IPv4, this is of course the number 4
2. Internet Header Length: Specifies the length of the IP header, in 32-bit words.
3. Type of service: information to provide quality of service features
4. Total Length
5. Identification: it can be used if the datagram must be fragmented by a router during delivery and then for reassembling.
6. Flags: (Don’t Fragment, More Fragment)
7. Fragment Offset: When fragmentation of a message occurs, this field specifies the offset, or position.
8. Time to Live: specifies how long the datagram is allowed to “live”
9. Protocol: ICMP, TCP, UDP, etc
10. Header Checksum: to provide basic protection against corruption in transmission.
11. Source Address
12. Destination Address
13. Options
14. Padding: if number of bits used for options is not a multiple of 32, then padding is added
15. Data