Open System Interconnection Reference Model 7 layer example?

Question

A long time ago I tried to study the Open System Interconnection Reference Model 7 layer network protocol standard and gave up after I couldn't find any actual examples of an application which used all 7 layers. Are there any examples now of applications which use and implement all 7 layers? Or are the highest few layers a product of the fevered imagination of a standards committee? Inquiring minds want to know.

Answer 1

There is one I know of: the NMS (Network Management System) protocols for managing SONET (Synchronous Optical NETwork) network elements. The CMISE protocol stack (if I recall correctly) is built on top of the recommended OSI model. You can get the relevant links to some documentation (I remember we had to buy those recommendations documents for mucho $$$) by searching for TelCordia GR-253.

Bear in mind that the OSI model is just what it is: a model. The real networks and protocols out there do not follow the OSI model that closely, believe me.

Answer 2

The International Organization for Standardization (ISO) developed the OSI model and also a suite of protocols which follow that model very closely.

Here is an example of a protocol stack using ISO protocols (this is the stack I used to work on 15 years ago when I was working on the management network for SONET telco equipment):

Layer 7 (Application): 
  ISO 8571: File Transfer Access and Management (FTAM)
  ISO 9596: Common Management Information Protocol (CMIP)

Layer 6 (Presentation): 
  ISO 8823: Presentation Layer Protocol

Layer 5 (Session):
  ISO 8327: Connection-oriented Session Protocol

Layer 4 (Transport):
  ISO 8073: Protocol for providing the connection-mode transport service  

Layer 3 (Network):
 ISO 8473: Protocol for providing the connectionless-mode network service

Layer 2 (Datalink):
  ISO 8802-2: Local and metropolitan area networks -- Specific requirements -- Part 2: Logical link control   

Layer 1:
  SONET DCC

These ISO/IEC protocols were somewhat widely used in the 80's and 90's, but these days they are only used in a few niche applications and the ISO/IEC protocols have mostly been replaced by the TCP/IP protocol stack which uses the ISO model only loosely.