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.

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