The SDH frame format is based on the synchronous transport module STM-1. The frame is organized in 9 rows and 270 columns consisting of 2430 bytes.
Out of the above bytes are section overheads while the remaining 2349 bytes form the payload. The higher rate frames are multiples of STM-1 and are labelled STM-N.
bytes are section overheads while the remaining 2349 bytes form the payload. The higher rate frames are multiples of STM-1 and are labelled STM-N. 
