Result: standard mapping
How many OC-12s are in an ODU4?
An ODU4 carries 160 OC-12s, per ITU-T G.709 and Telcordia GR-253. This path maps OC-192 into ODU2 as a client, then follows that client's tributaries.
160
OC-12s in an ODU4
Working
ODU4 → 10 × ODU2 → 1 × OC-192 → 16 × OC-12
- 10 × ODU2 in each ODU4 ITU-T G.709Ten ODU2s use all 80 tributary slots, eight slots each.
- 1 × OC-192 in each ODU2 ITU-T G.709Client mappingCBR OC-192, the same client rate as STM-64, mapped into OPU2.
- 16 × OC-12 in each OC-192 Telcordia GR-25316 × OC-12. Channelized OC-192 is 192 STS-1s.
- 10 ODU2s
- 10 × 1 = 10 OC-192s
- 10 × 1 × 16 = 160 OC-12s
Leftover capacity
5.261645815 Gbit/s of each ODU4 line rate (104.794445815 Gbit/s) sits outside 160 × 622.080 Mbit/s of OC-12 line rate (99.532800 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 168.45, which floors to 168 OC-12s by bit rate only. The standard mapping is 160. Use the mapping.