SDH or Sonet (U.S.A) delimit the cells by code HEC by using way STM1 Synchrone Mode
Transport bases synchronous hierarchy.
STM1 is composed of 9 columns of 270 bytes.
The first 9 columns are reserved for the functions of maintenance and exploitation.
The second column shows the way.
The 260 following columns carry the data.
Productive flow of STM1 offered to layer ATM : 149,76 MB/s
Productive flow of outgoing STM1 of layer ATM : 135,63 MB/s
In general ways STM are assembled in groups to constitute units of information to high flow.
- STM4 corresponds to 4 ways => flow of 620 Mb/s
- STM16 corresponds to 16 ways => flow of 2.4 Gb/s