Answer to Question #317719 in Computer Networks for fal

Question

 Discuss the IPv4 Datagram with the help of suitable examples

Answer 1

The IPv4 Datagram comprises of a header part and a body part in which the header has a 20-byte fixed part and optional part of variable-length.

These parts are discussed as follows:

• Version – this refers to the 4-bit field that defines the IPv4 protocol version. It ensures that all fields follow the fourth version interpretation specified by the protocol version.
• Header length (HLEN) – this defines the datagram header’s total length in 4-byte words and is needed due to the variability of the header’s length.
• Fragment offset – shows the number of data bytes in front of a certain fragment in a specific datagram. The numbers are specified in terms of 8 bytes and have 65,528 bytes as the maximum value.
• Time to live – as the datagram travels through an internet, it has a limited lifetime. As a result, this scheme requires all machines to have synchronized clocks and have the capability of knowing the time a datagram takes to move from one machine to the other. This field is applied in controlling the maximum number of hops a datagram visits.
• Protocol – as an IPv4 datagram can function by encapsulating data from protocols of higher-levels, this field ensures that there is a specified final destination protocol to which the delivery of IPv4 datagram is done. Hence, this section is responsible for helping the receiving network layer know the data belongs to which protocol.
• Checksum – this field is used to check errors in the datagram. It happens when the by dividing the entire header into 16-bit sections and adding them together. The outcome is complemented and put in the checksum field.
• Source and destination address – this is the field that remains unchanged when the IPv4 datagram is traveling from the source host to the destination host. An example is the address of the sender and receiver.
• Option – refers to the optional information including record route and source route. This one is essential to network administrators as they use it to check the functionality of a path.