Result: standard mapping
How many STM-1s are in an ODU0?
An ODU0 carries 4 STM-1s, per ITU-T G.709 and ITU-T G.707. This path maps STM-4 into ODU0 as a client, then follows that client's tributaries.
4
STM-1s in an ODU0
Working
ODU0 → 1 × STM-4 → 4 × STM-1
- 1 × STM-4 in each ODU0 ITU-T G.709Client mappingCBR STM-4 mapped into OPU0.
- 4 × STM-1 in each STM-4 ITU-T G.7074 × STM-1.
- 1 STM-4
- 1 × 4 = 4 STM-1s
Leftover capacity
622.080 Mbit/s of each ODU0 line rate (1.244160 Gbit/s) sits outside 4 × 155.520 Mbit/s of STM-1 line rate (622.080 Mbit/s). That remainder is overhead, fixed stuff or justification. It is not another whole tributary.
By bit rate only
Dividing the line rates gives 8, which floors to 8 STM-1s by bit rate only. The standard mapping is 4. Use the mapping.