Network Layer Security

INTRODUCTION Modern computer networks are characterized by layered protocol architectures, allowing network designs to accommodate unlimited applications and interconnection techniques. This layered approach allows protocols to become modularized; that is, developed independently and put together with other protocols in such a way as to create one complete protocol. The recognized basis of protocol layering is the open systems interconnection (OSI) architecture. The OSI standards establish the architectural model and define specific protocols to fit into this model, which defines seven layers. Protocols from each of the layers are grouped together into an OSI layer stack, which is designed to fulfill the communications requirements of an application process. Standards are also needed to adequately support security in the OSI layered communications architecture. A broad, coordinated set of standards is required to ensure necessary security functionality and still provide a cost-effective implementation. Because of the complexity and flexibility of the OSI model, security must be carefully defined to avoid an increased potential for functions being duplicated throughout the architecture and incompatible security features being used in different parts of the architecture. There is also a possibility that different and potentially contradictory security techniques can be used in different applications or layers, where fewer techniques would provide the required results with less complexity and more economy. Security standards were added to the OSI architecture to provide a P A Y O F F I D E A