The fast technological developments in the field of data communication have been materialized in a variety of products which claim to solve the user's requirements for networking. On the other hand, the users have precipitated this invasion by calling for increased connectivity, higher reliability, lower costs in networking and support for interconnecting hetergeneous equipment. The result of this situation is that the user has a difficult task in developing strategies for its environment in order to get unscathed~through the product jungle of the market." (implementing the iso-osi reference model, r. popescu-zeletin osireferencemodel (application/pdf, 785 KB)