A method for discarding data packets destined for a mobile station connected to both a master base station and a secondary base station, wherein the data packets are forwarded from the master base station via the secondary base station to the mobile station, wherein a higher layer with a master discard function is located at the master base station but not at the secondary base station, the master discard function discarding data packets upon expiry of a master timer started upon reception of each data packet, the method characterized by comprising the steps of: configuring by the master base station a secondary discard function in a lower layer of the secondary base station, based on the master discard function in the higher layer of the master base station, forwarding by the master base station the data packet from the higher layer to the lower layer of the secondary base station, and discarding by the secondary discard function of the lower layer at the secondary base station the received data packet upon expiry of a secondary timer started by the lower layer upon reception of the data packet from the higher layer at the master base station, wherein the higher layer at the master base station is a PDCP layer, the lower layer at the secondary base station is an RLC layer, and the data packet is received by the PDCP layer as a PDCP SDU and forwarded to the RLC layer as a PDCP PDU, generated by the PDCP layer out of the received PDCP SDU, such that the secondary discard function of the RLC layer at the secondary base station discards the received PDCP PDU upon expiry of the secondary timer started by the RLC layer upon reception of the PDCP PDU from the PDCP layer at the master base station, upon reception of the PDCP SDU, starting by the PDCP layer at the master base station the master timer of the master discard function for the received PDCP SDU, upon receiving by the master base station an indication that the generated PDCP PDU was successfully forwarded to the mobile station, discarding by the PDCP layer at the master base station the received PDCP SDU and the generated PDCP PDU, wherein the received indication is transmitted by the secondary base station to the master base station, and includes information on one or more PDCP PDUs successfully forwarded by the secondary base station to the mobile station. configuring by the master base station a secondary discard function in a lower layer of the secondary base station, based on the master discard function in the higher layer of the master base station, forwarding by the master base station the data packet from the higher layer to the lower layer of the secondary base station, and discarding by the secondary discard function of the lower layer at the secondary base station the received data packet upon expiry of a secondary timer started by the lower layer upon reception of the data packet from the higher layer at the master base station, wherein the higher layer at the master base station is a PDCP layer, the lower layer at the secondary base station is an RLC layer, and the data packet is received by the PDCP layer as a PDCP SDU and forwarded to the RLC layer as a PDCP PDU, generated by the PDCP layer out of the received PDCP SDU, such that the secondary discard function of the RLC layer at the secondary base station discards the received PDCP PDU upon expiry of the secondary timer started by the RLC layer upon reception of the PDCP PDU from the PDCP layer at the master base station, upon reception of the PDCP SDU, starting by the PDCP layer at the master base station the master timer of the master discard function for the received PDCP SDU, upon receiving by the master base station an indication that the generated PDCP PDU was successfully forwarded to the mobile station, discarding by the PDCP layer at the master base station the received PDCP SDU and the generated PDCP PDU, wherein the received indication is transmitted by the secondary base station to the master base station, and includes information on one or more PDCP PDUs successfully forwarded by the secondary base station to the mobile station.