Methods, apparatus, and computer programs for processing packets. The method includes receiving a packet at a first port of an apparatus, wherein the packet (i) is associated with a first session of a plurality of sessions being maintained by the apparatus and (ii) includes a first transmit window size associated with the first session; storing the packet in a packet buffer prior to retransmitted the packet from the apparatus, the packet buffer having a predetermined size; modifying the first transmit window size as set forth in the first packet based on (i) the predetermined size of the packet buffer, and (ii) a second transmit window size associated with a second session of the plurality of sessions, wherein the second session is separate from the first session; and transmitting the packet having the modified first transmit window size from a second port of the apparatus.