At present, there are two packages of 200G DAC: QSFP-DD DAC and QSFP56 DAC. The wavelength of 850nm, power consumption is very small to be ignored, but the farthest transmission distance is only 5M.
QSFP-DD DAC has 8 transmitting and receiving ports, transmission rate of each one is 25G, and the modulation method is NRZ.
QSFP56 DAC has 4 ports which are two transmitting and receiving, transmission rate of each port is 53G.
①200G QSFP56 DAC to 2x100G QSFP28 DAC
One port is connected with 200G QSFP56 optical transceiver and the other one is connected with two 100G QSFP28 optical transceivers, which is mainly used in the 200G to 2-channel 100G network on the same rack in the data center. The transmission distance is 3 meters and maximum rate is 212.5Gbps.
②200G QSFP56 DAC to 4x50G SFP56 DAC
One port is connected with 200G QSFP56 optical transceiver and the other one is connected with four SFP56 optical transceivers. The transmission distance is 3 meters, mainly used in the same rack 200G to 4 way 50G equipment.
With the continuous expansion of data center and increasing the rate, the cost is accordingly increased. Compared with 200G AOC, the power consumption of 200G DAC is much smaller and price is much lower. It's more popular with the ultra-short-distance data center transmission.
