Numbering Schemes for SDH Timeslots

VC12 Timeslot Numbering

Two numbering schemes are applicable to SDH optical/electrical lines or SDH microwave links when you create cross-connections.

• By order

  This timeslot numbering scheme is also considered as timeslot scheme, where the numbering formula is as follows: VC12 number = TUG-3 number + (TUG-2 number - 1) x 3 + (TU-12 number -1) x 21.

  This scheme is the numbering scheme recommended by ITU-T G.707, which is the default scheme adopted by the OptiX equipment.

• Interleaved scheme

  This timeslot numbering scheme is also considered as line scheme, where the numbering formula is as follows: VC12 number = (TUG-3 number - 1) x 21 + (TUG-2 number -1) x 3 + TU-12 number.

  The OptiX equipment can adopt this scheme when it interconnects with the equipment that adopts the interleaved scheme or when specific timeslot numbering scheme is required.

Figure 1 Numbering VC12 timeslots by order

Figure 2 Numbering VC12 timeslots in the interleaved scheme

VC3 Timeslot Numbering

A VC3 timeslot number corresponds to a TUG-3 number. If you need to configure VC3 cross-connections and VC12 cross-connections in a VC4 path at the same time, note that the timeslots in the TUG-3 that are occupied by the VC3 cross-connections cannot be configured for VC12 cross-connections.