ABSTRACT
Modern computer networks today are characterized by
layered protocol architectures, allowing network designs
to accommodate unlimited applications and interconnec-
tion 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) archi-
tecture. 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 require-
ments of an application process.