OSI (Open Systems Interconnection) is a 7-layer network model specified by ISO (International Organization for Standardization) norm and is widely used all around the world. The concept of a seven-layer model was provided by the work of Charles Bachman, Honeywell information Services. Various aspects of OSI design evolved from experiences with the ARPANET, NPLNET, EIN and CYCLADES networks and the work in IFIP WG6.1.