Difference between dense wavelength division multiplexing and OTN

OTN is an optical transport network, which is actually a combination of DWDM (Dense Optical Multiplexing) and ASON (Automatic Optical Switching Network). First of all, OTN has optical crossover capability, that is, by loading WSS ROADM module, it can form a mesh network structure similar to ASON equipment, which not only improves the flexibility of service scheduling, but also increases network security; Secondly, OTN has the electrical crossover capability, that is, the sub-rate crossover capability of each channel, which is very similar to SDH, but OTN has its own special frame structure, namely, ODU 1 for 2.5G particles and ODU-2 for 10G particles, as well as ODU 1E and ODU2E for data services.

The same is true for GE service, because most nodes only need 1 ~ 2ge instead of 8 ~ 9ge. In order to solve this problem, it is necessary to introduce SDH-like crossover function into DWDM to evolve the electrical crossover function of OTN. The electrical crossover part of OTN is actually equivalent to SDH equipment which can only dispatch 2.5G and 10G particles at one end, and its customer end part is a color optical port, which is connected with the service equipment. The service signal is connected to the crossover matrix through the customer end, multiplexed into ODU 1 or ODU2 particles, and then converted into DWDM-compliant wavelength by OTU on the line side, and transmitted on the optical cable through OMU, ODU and o a. It can be seen that OTN can actually be compared to the combination of DWDM and ASON, but it should be noted that OTN can hardly support services below 2.5G