A network device for forwarding traffic with a plurality of output ports (120-1 to 120-N, 520-1-520-N), comprising: a storage system (101, 530) storing forwarding rules including a first rule for forwarding packets of flows of an aggregated flow according to a given flow distribution to the output ports; a circuitry (110, 510) configured to: in a case where the load on a first output port (120-N, 520-N) does not match a target load for the first output port, exclude at least one of the flows from the aggregated flow and modify said stored forwarding rules by establishing a second rule associating the at least one of the flows of the aggregated flow with a second output port (120-1, 520-1) so as to improve the match between the target load and the load on the first output port; and perform routing according to the stored forwarding rules; wherein the load on the first output port (120-N, 520-N) is a measured load or a predicted load; wherein the circuitry (110, 510) is configured to: predict a future load on the output ports (520-1 to 520-N); in a case where the predicted future load on the first output port (520-N) does not match the target load for the first output port (520-N), identify the at least one of the flows with the heaviest future load among the flows (550-1 to 550-N) of the aggregated flow forwarded to the first output port (520-N) according to the flow forwarding rules; associate said identified flow to the second output port. a storage system (101, 530) storing forwarding rules including a first rule for forwarding packets of flows of an aggregated flow according to a given flow distribution to the output ports; a circuitry (110, 510) configured to: in a case where the load on a first output port (120-N, 520-N) does not match a target load for the first output port, exclude at least one of the flows from the aggregated flow and modify said stored forwarding rules by establishing a second rule associating the at least one of the flows of the aggregated flow with a second output port (120-1, 520-1) so as to improve the match between the target load and the load on the first output port; and perform routing according to the stored forwarding rules; wherein the load on the first output port (120-N, 520-N) is a measured load or a predicted load; wherein the circuitry (110, 510) is configured to: predict a future load on the output ports (520-1 to 520-N); in a case where the predicted future load on the first output port (520-N) does not match the target load for the first output port (520-N), identify the at least one of the flows with the heaviest future load among the flows (550-1 to 550-N) of the aggregated flow forwarded to the first output port (520-N) according to the flow forwarding rules; associate said identified flow to the second output port. in a case where the load on a first output port (120-N, 520-N) does not match a target load for the first output port, exclude at least one of the flows from the aggregated flow and modify said stored forwarding rules by establishing a second rule associating the at least one of the flows of the aggregated flow with a second output port (120-1, 520-1) so as to improve the match between the target load and the load on the first output port; and perform routing according to the stored forwarding rules; wherein the load on the first output port (120-N, 520-N) is a measured load or a predicted load; wherein the circuitry (110, 510) is configured to: predict a future load on the output ports (520-1 to 520-N); in a case where the predicted future load on the first output port (520-N) does not match the target load for the first output port (520-N), identify the at least one of the flows with the heaviest future load among the flows (550-1 to 550-N) of the aggregated flow forwarded to the first output port (520-N) according to the flow forwarding rules; associate said identified flow to the second output port. predict a future load on the output ports (520-1 to 520-N); in a case where the predicted future load on the first output port (520-N) does not match the target load for the first output port (520-N), identify the at least one of the flows with the heaviest future load among the flows (550-1 to 550-N) of the aggregated flow forwarded to the first output port (520-N) according to the flow forwarding rules; associate said identified flow to the second output port.