Path Layer

The path  layer maps services  such as DS3, FDDI, and ATM into the SONET  payload formal. This layer  provides  end to end  communications  signals  labelling path maintenance and control  and is accessible only  through terminating equipment. A SONET  ADM accesses the path  layer overhead a cross  connect  systems that performs  section and line layer processing does  not require  access to  the path  layer overhead.