textarea=The functions within the OSI model can be roughly divided into two groups. The upper group, comprised of layers 5 through 7, is referred to as the Application or Interoperability layers. These layers are generally implemented in software and enable communication between applications. The lower group, comprised of layers 1 through 4, is referred to as the Transport or Internetworking layers. They are generally implemented in both hardware and software and enable communication between nodes on a network.