In one implementation, a network device is configured to implement an intra switch transport protocol. The intra switch transport protocol is configured to determine a maximum window size according to a predetermined bandwidth and a round trip time between a plurality of ingress ports and an egress port. The network device is configured to calculate an assigned window value for the one of the plurality of ingress ports based on the maximum window size and generate an acknowledgment message including the assigned window value for the one of the plurality of ingress ports, and to delay successive acknowledgement messages according to fabric congestion and egress port occupancy.