In response to a first channel associated with a first OLT and a second channel associated with a second OLT being enabled for target traffic, a traffic scheduler for scheduling the target traffic is determined by the first OLT. The first channel and the second channel correspond to a first wavelength and a second wavelength, respectively. The first OLT transmits channel configurations and offset information to an ONU, based on scheduling of a first group of data units and a second group of data units of the target traffic by the traffic scheduler on the first channel and the second channel, respectively. The channel configurations indicate channel identifications associated with the first channel and the second channel, and the offset information indicates timing information of the first group of data units and the second group of data units corresponding to physical frames transmitted on the first and second channels.