Networking?

Hi, i have done some past papers (OCR 2506) and i am stuck on 2 questions and need help with it:





1) A computer is to use a printer to provide hardcopy output of jobs. In order for the data to be transmitted and recieved properly a protocol must be set up between the two pieces of hardware. State two parts of the protocol which would be essential in this example, giving reasons why they are necessary. (4)





2) Explain the term "layered interface" when describing intercomminication between devices and sate a reason for arrangeing the interface between devices in a layered fashion.





I am only completely stuck on these two questions and dont have a clue how to answer them, any help would be great

Networking?
1) Context suggests they are looking for something like LPR / LPD ?





2) Here I guess they must mean the "OSI seven layer model" ..