The Benefits of Using a Layered Model
The benefits to using a layered model to describe network protocols and operations include:
Assisting in protocol design because protocols that operate at a specific layer have defined information that they act upon and a defined interface to the layers above and below.
Fostering competition because products from different vendors can work together.
Preventing technology or capability changes in one layer from affecting other layers above and below.
Providing a common language to describe networking functions and capabilities.
As shown in the figure, the TCP/IP model and the Open Systems Interconnection (OSI) model are the primary models used when discussing network functionality. They each represent a basic type of layered networking models:
Protocol model - This type of model closely matches the structure of a particular protocol suite. The TCP/IP model is a protocol model because it describes the functions that occur at each layer of protocols within the TCP/IP suite. TCP/IP is also used as a reference model.
Reference model - This type of model provides consistency within all types of network protocols and services by describing what has to be done at a particular layer, but not prescribing how it should be accomplished. The OSI model is a widely known internetwork reference model, but is also a protocol model for the OSI protocol suite.