OSI layer and orgin

I always surprised how OSI team made this perfect model, when there is no idea of images and audio in datacommunication. When layers worktogather the updation of any individual layer will not affect other layer operation.  For eg: changing of any physical layer media cable Cat 5 to Cat 5e will not affect the operation of other layer.

                              In 1978 ISO group met in Washington, DC the Honeywell team presented their OSI solution standerized later in 1979.

David Paul

facebook.com/davidprasad