Multi-mode optical modules are applicable to short-distance transmission, while single-mode optical modules are applicable to long-distance transmission. Single-mode optical modules will be widely used in future.
NOTE:
Some single-mode optical modules need optical attenuators, but some do not need. This depends on the transmit/receive power of the optical module and the transmission distance.

Multiple types of Huawei devices can use the same type of optical module. For details, see the product hardware description.