Communication protocols enable an entity in one host to interact with a corresponding entity at the same layer in another host. Service definitions, like the OSI model, abstractly describe the functionality provided to a layer N by a layer N−1, where N is one of the seven layers of protocols operating in the local host.
communication protocols enable an entity in one host to interact with a corresponding entity at the same layer in another host service definitions like the osi model abstractly describe the functionality provided to a layer n by a layer n−1 where n is one of the seven layers of protocols operating in the local host