Method for receiving and delivering section overheads of and for STM-1 signals in a section-overhead server of a network node

A method for cross-connecting synchronous transfer module signals in a network node of a digital transmission system, the network node having a space-division switching network connected to synchronous transfer module interface units and to a section overhead server, and having a processor connected to the section overhead server and to the synchronous transfer module interface units, the method comprising the steps of:

• converting in a receiving section of each of said synchronous transfer module interface units a received one of said synchronous transfer module signals having a section overhead into four D39 signals, each of said D39 signals having a byte frame of 152 rows and 16 columns;
• inserting overhead bytes of the section overhead except frame synchronization bytes and bytes for determining a bit error rate into an unoccupied special column of one of said D39 signals;
• supplying overhead bytes only of said special column to the section overhead server via the space-division switching network for each said received synchronous transfer module signal;
• generating overhead bytes except said frame synchronization bytes and said bytes for determining the bit error rate in the section overhead server for each outgoing one of said synchronous transfer module signals;
• cross-connecting said four D39 signals via the spaced-division switching network to a transmitting section of one of said synchronous transfer module interface units;
• inserting the overhead bytes generated in said step of generating into the special column of one of said four D39 signals;
• and
• converting said four D39 signals into an outgoing synchronous transfer module signal.