Result: standard mapping
How many DS2s are in an OTU3?
An OTU3 carries 5,376 DS2s, per ITU-T G.709 and Telcordia GR-253. This path maps OC-768 into ODU3 as a client, then follows that client's tributaries.
5,376
DS2s in an OTU3
Working
OTU3 → 1 × ODU3 → 1 × OC-768 → 768 × OC-1 (STS-1) → 7 × DS2
- 1 × ODU3 in each OTU3 ITU-T G.709The OTU3 frame carries exactly one ODU3.
- 1 × OC-768 in each ODU3 ITU-T G.709Client mappingCBR OC-768, the same client rate as STM-256, mapped into OPU3.
- 768 × OC-1 (STS-1) in each OC-768 Telcordia GR-253768 × OC-1 (STS-1). Channelized OC-768 is 768 STS-1s.
- 7 × DS2 in each OC-1 (STS-1) Telcordia GR-253Seven VT groups, one VT6 (DS2) each.
- 1 ODU3
- 1 × 1 = 1 OC-768
- 1 × 1 × 768 = 768 OC-1s
- 1 × 1 × 768 × 7 = 5,376 DS2s
Leftover capacity
9.085101559 Gbit/s of each OTU3 line rate (43.018413559 Gbit/s) sits outside 5,376 × 6.312 Mbit/s of DS2 line rate (33.933312 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 6,815.33, which floors to 6,815 DS2s by bit rate only. The standard mapping is 5,376. Use the mapping.