Cluster networks will serve as the future access networks for multimedia streaming, massive multiplayer online gaming, e-commerce, network storage etc. And for those application areas provisioning of Quality of Service (QoS) is becoming and important issue. DiffServ as specified by the IETF is foreseen to be the most prominent concept for providing predictability in the future Internet. To enable seamless interoperation with the higher level IETF concepts the QoS architecture of the lower layers should comply with the DiffServ paradigm as well. Previous work on predictability in cut-through networks has only studied class based QoS. In this paper we set out to achieve flow level QoS using flow aware admission control in combination with a flow negligent DiffServ inspired QoS mechanism. Our results show that flow level bandwidth guarantees are achievable with the use of the Link-by-Link and the Probe based schemes. In addition we are able to achieve an order of magnitude improvement in jitter and latency in individual flows.