A method, comprising: determining, by a forwarding device, an outbound timeslot set, wherein the outbound timeslot set comprises multiple timeslots used when the forwarding device sends, to a first device by using an outbound flexible Ethernet, FlexE, group, multiple encoded data blocks generated by a physical coding sublayer, and the multiple timeslots comprised in the outbound timeslot set are in a one-to-one correspondence with the multiple encoded data blocks; determining, by the forwarding device, an inbound timeslot set, wherein the inbound timeslot set comprises multiple timeslots used when the forwarding device receives, by using an inbound FlexE group, the multiple encoded data blocks sent by a second device and the multiple timeslots comprised in the inbound timeslot set are in a one-to-one correspondence with the multiple encoded data blocks; generating, by the forwarding device, a mapping relationship between the multiple timeslots comprised in the inbound timeslot set of the inbound FlexE group and the multiple timeslots comprised in the outbound timeslot set of the outbound FlexE group; receiving, by the forwarding device, from the second device, the multiple encoded data blocks by using the multiple timeslots comprised in the inbound timeslot set; and sending, by the forwarding device, to the first device based on the mapping relationship, the multiple encoded data blocks by using the multiple timeslots comprised in the outbound timeslot set; wherein the forwarding device skips performing layer 2 or layer 3 processing on the multiple encoded data blocks after receiving the multiple encoded data blocks by using the multiple timeslots comprised in the second timeslot set, and before sending the multiple encoded data blocks by using the multiple timeslots comprised in the first timeslot set. determining, by a forwarding device, an outbound timeslot set, wherein the outbound timeslot set comprises multiple timeslots used when the forwarding device sends, to a first device by using an outbound flexible Ethernet, FlexE, group, multiple encoded data blocks generated by a physical coding sublayer, and the multiple timeslots comprised in the outbound timeslot set are in a one-to-one correspondence with the multiple encoded data blocks; determining, by the forwarding device, an inbound timeslot set, wherein the inbound timeslot set comprises multiple timeslots used when the forwarding device receives, by using an inbound FlexE group, the multiple encoded data blocks sent by a second device and the multiple timeslots comprised in the inbound timeslot set are in a one-to-one correspondence with the multiple encoded data blocks; generating, by the forwarding device, a mapping relationship between the multiple timeslots comprised in the inbound timeslot set of the inbound FlexE group and the multiple timeslots comprised in the outbound timeslot set of the outbound FlexE group; receiving, by the forwarding device, from the second device, the multiple encoded data blocks by using the multiple timeslots comprised in the inbound timeslot set; and sending, by the forwarding device, to the first device based on the mapping relationship, the multiple encoded data blocks by using the multiple timeslots comprised in the outbound timeslot set; wherein the forwarding device skips performing layer 2 or layer 3 processing on the multiple encoded data blocks after receiving the multiple encoded data blocks by using the multiple timeslots comprised in the second timeslot set, and before sending the multiple encoded data blocks by using the multiple timeslots comprised in the first timeslot set.