Having some unified concept of them is nice for trouble shooting and communicating concepts; especially in network design. Helps you understand what depends on

Having some unified concept of them is nice for trouble shooting and communicating concepts; especially in network design. Helps you understand what depends on what and in some cases what certain protocols are limited by (see: broadcast domains). I personally prefer the 5 layer TCP/IP model to the 7 layer OSI model. To me the Application, Presentation, and Session layers blur into one.