Result: standard mapping
How many DS0s are in an OTU3?
An OTU3 carries 516,096 DS0s, per ITU-T G.709, ITU-T G.707 and ANSI T1.107. This path maps STM-256 into ODU3 as a client, then follows that client's tributaries.
516,096
DS0s in an OTU3
Working
OTU3 → 1 × ODU3 → 1 × STM-256 → 256 × STM-1 → 84 × DS1 → 24 × DS0
- 1 × ODU3 in each OTU3 ITU-T G.709The OTU3 frame carries exactly one ODU3.
- 1 × STM-256 in each ODU3 ITU-T G.709Client mappingCBR STM-256 mapped into OPU3.
- 256 × STM-1 in each STM-256 ITU-T G.707256 × STM-1.
- 84 × DS1 in each STM-1 ITU-T G.70784 VC-11 tributaries: 3 TUG-3 × 7 TUG-2 × 4 TU-11.
- 24 × DS0 in each DS1 ANSI T1.10724 payload timeslots. The framing bit adds 8 kbit/s and brings the line rate to 1.544 Mbit/s.
- 1 ODU3
- 1 × 1 = 1 STM-256
- 1 × 1 × 256 = 256 STM-1s
- 1 × 1 × 256 × 84 = 21,504 DS1s
- 1 × 1 × 256 × 84 × 24 = 516,096 DS0s
Leftover capacity
9.988269559 Gbit/s of each OTU3 line rate (43.018413559 Gbit/s) sits outside 516,096 × 64 kbit/s of DS0 line rate (33.030144 Gbit/s). That remainder is overhead, fixed stuff or justification. It is not another whole tributary.
By bit rate only
Dividing the line rates gives 672,162.71, which floors to 672,162 DS0s by bit rate only. The standard mapping is 516,096. Use the mapping.