Assignemnt: OSI Model
Describe the open systems interconnection (OSI) model and how it relates to a network in 200 to 350 words. Include answers to the following:
•	On which layers of the OSI model do WAN protocols operate?
•	What are some of these protocols?
•	On which OSI layers do switches and routers operate?
•	If routers reside at more than one layer, what is the difference between OSI layers?