A network protocol defines rules and conventions for communication between network devices.

It includes mechanisms for devices to identify and make connections with each other, formatting rules that specify how data should be packaged, and rules on how these packages are sent and received

Protocol suites

A protocol suite is a set of protocols designed to work together, Examples include TCP/IP, Industrial controls/SCADA, Zigbee, Bluetooth, and cellular (4G, 5G, LTE) etc

Each layer of protocol software ensures that the message arrives as expected

• protocol software on the two machines must exchange information

• each layer on the sender prepends extra information onto the packet

• the corresponding protocol layer on the receiver removes and uses the extra information

• Additional information added by a protocol is known as a header

• Headers are added by protocol software on the sending computer

• That is, the Transport layer prepends a header, and then the Internet layer prepends a header, and so on 16