1.1 Layered Architectures
nNetworking protocols are developed in layers so as to
simplify the task of 1) developing new services
and 2) upgrading and maintaining the
system.
nEach layer performs a well defined function. The internals
of a layer can be changed without
affecting the neighboring layers.
nLayers exchange information via clearly specified interfaces.
nLayers communicate
on a peer
to peer basis.