Result: standard mapping
How many DS3s are in an ODU4?
An ODU4 carries 1,920 DS3s, per ITU-T G.709 and ITU-T G.707. This path maps STM-64 into ODU2 as a client, then follows that client's tributaries.
1,920
DS3s in an ODU4
Working
ODU4 → 10 × ODU2 → 1 × STM-64 → 64 × STM-1 → 3 × DS3
- 10 × ODU2 in each ODU4 ITU-T G.709Ten ODU2s use all 80 tributary slots, eight slots each.
- 1 × STM-64 in each ODU2 ITU-T G.709Client mappingCBR STM-64 mapped into OPU2.
- 64 × STM-1 in each STM-64 ITU-T G.70764 × STM-1.
- 3 × DS3 in each STM-1 ITU-T G.707Three VC-3s, each able to carry a DS3.
- 10 ODU2s
- 10 × 1 = 10 STM-64s
- 10 × 1 × 64 = 640 STM-1s
- 10 × 1 × 64 × 3 = 1,920 DS3s
Leftover capacity
18.901325815 Gbit/s of each ODU4 line rate (104.794445815 Gbit/s) sits outside 1,920 × 44.736 Mbit/s of DS3 line rate (85.893120 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 2,342.5, which floors to 2,342 DS3s by bit rate only. The standard mapping is 1,920. Use the mapping.