Result: standard mapping
How many DS1s are in an ODU3?
An ODU3 carries 21,504 DS1s, per ITU-T G.709 and ITU-T G.707. This path maps STM-256 into ODU3 as a client, then follows that client's tributaries.
21,504
DS1s in an ODU3
Working
ODU3 → 1 × STM-256 → 256 × STM-1 → 84 × DS1
- 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.
- 1 STM-256
- 1 × 256 = 256 STM-1s
- 1 × 256 × 84 = 21,504 DS1s
Leftover capacity
7.117042983 Gbit/s of each ODU3 line rate (40.319218983 Gbit/s) sits outside 21,504 × 1.544 Mbit/s of DS1 line rate (33.202176 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 26,113.48, which floors to 26,113 DS1s by bit rate only. The standard mapping is 21,504. Use the mapping.