The Protocol field in the IPv4 header contains a number indicating the type of data found in the payload portion of the datagram. (What kind of data is present?)
Datagram is presented with protocol using a number. UDP or TCP. UDP is presented by 17, and TCP presented by 7.
ICMP – Internet Control Message Protocol
8 bit (0-255)
Source IP (32-bits)
The computer transmitting data is the source.
Destination IP Address (32-bits)
The computer receiving the data is the destination.
The IP Addresses of the Source and Destination will get accommodated in these two fields.