The TCP/IP Guide  9  Networking Fundamentals       9  Fundamental Network Characteristics

Networking Layers, Models and Architectures 1 2 Circuit Switching and Packet Switching Networks

Different Uses of the Word “Protocol”

Despite the strict OSI definition, the term “protocol” is often used colloquially to refer to many different concepts in networking. Some of the more common “alternative” uses of the word include the following:

• Protocol Suites: It is very common to hear the word “protocol” used to refer to sets of protocols that are more properly called protocol suites (or stacks, in reference to a stack of layers). For example, TCP/IP is often called just a “protocol” when it is really a (large) set of protocols.
  
  Sometimes, the name of the technology itself leads to this confusion. The Point-to-Point Protocol (PPP), for example, is not one protocol; it contains many individual protocols that serve different functions and even have distinct message formats. Thus, PPP is really a protocol suite, or alternately, can be considered a protocol with “sub-protocols”.
  
  
• Microsoft Windows Protocols: One important example of the issue of referring to protocol suites as single protocols is the networking software in Microsoft Windows. It usually calls a full networking stack like TCP/IP or IPX/SPX just a “protocol”. When you install one of these “protocols”, however, you actually get a software module that supports a full protocol suite.
  
  
• Other Technologies: Sometimes technologies that are not protocols at all are called protocols, either out of convention or perhaps because people think it sounds good. For example, TCP/IP Remote Network Monitoring (RMON) is often called a protocol when it is really just an enhancement to the Simple Network Management Protocol (SNMP)—which is a protocol!

So, does it really matter whether a protocol is a “true” protocol or not? Well, the networking hardware devices and software programs sure don’t care. J But hopefully having read about the term and what it means, you will be able to better understand the word when you encounter it in your studies—especially in the places where it may not always be used in a way entirely consistent with its formal definition.

Networking Layers, Models and Architectures 1 2 Circuit Switching and Packet Switching Networks