Result: standard mapping
How many DS2s are in an ODU3?
An ODU3 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 ODU3
Working
ODU3 → 1 × OC-768 → 768 × OC-1 (STS-1) → 7 × DS2
- 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 OC-768
- 1 × 768 = 768 OC-1s
- 1 × 768 × 7 = 5,376 DS2s
Leftover capacity
6.385906983 Gbit/s of each ODU3 line rate (40.319218983 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 6,387.7, which floors to 6,387 DS2s by bit rate only. The standard mapping is 5,376. Use the mapping.