The following rules apply to trunk connection via STMA:

• Configure the STMA with BCSU and BDAT in the same way. The innovation only affects the AMO TDCSU.
• The new device type ATMPVCCO in the AMO TDCSU is similar to the old device type ATMPVC30, which means that you can configure a maximum of 4 S2 trunk circuits for each STMA.
• The clock production can only be implemented for each STM-1 interface.
• You can add the ATMPVCCO circuits to existing ATMPVC and ATMSVC circuits if there are still enough free time slots or ports. In this regard, an ATMPVCCO circuit behaves like an ATMPVC30 circuit. All other rules that apply to ATMPVC circuits also apply in this case (for example, you cannot switch on the ATMPVCCO circuit until you have switched off all ATMSVCs that are configured on the STMA.
• For STMA trunk access, only device type ATMPVCCO with a maximum of 30 B channels is possible.
• The ATM-specific parameters in the AMO TDCSU of the ATMPVCCO circuit (VPI, VCI, PORT, etc.) correspond exactly to those of the ATMPVC30.
  • Always set the filling level parameter to the default value FILLLEV=47.
  • You can select all other TDCSU parameters (COP, COT, COS, etc.) in exactly the same way as for the previously known S0/S2 trunk access via DIU-S2 or STMD.
  • The exception is the COP parameter RRST, which you must also set on all ATMPVC circuits (but there is an appropriate message if this parameter is missing and you cannot configure the circuit without it).
  • The circuit seizure order (TDCSU parameter SRCHMODE) should - if possible - be set to the opposite of that of the central office system. That is, if the central office system is set to linear-increasing, the ATMPVCCO should be set to linear-decreasing and vice versa.
• The STMA is connected to the STM-1 interface of the ATM switch. You must connect the S2 trunk with a CES-E1 interface of the ATM switch. Configure a PVC with a bandwidth of 2244 Kbps (when filling level = 47 on the STMA) in the ATM switch between the STM-1 and CES-E1 port.