Question & Answer: 1) Compare and contrast the protocol field at the network layer with the port numbers at the transport layer……

Both the protocol field and the port numbers both have the same functionality of multiplexing and de-multiplexing. Port numbers are used to do these tasks at the transport layer and the protocol field is used to do the same task at the network layer. Only one protocol field is required at the network layer because payload taken from a protocol at the source should be carried to the same protocol at the destination. On the other hand, the client and server procedures generally have different port numbers, which means two port numbers are required to define the processes. The size of the protocol field defines the total number of different protocols that use the service of the network layer, which is a small number i.e. 8 bit here. On the other hand, many new applications may be added every day that needs a larger size of the port number field i.e. 16 bits.