Crossbow: A Vertically Integrated Qos Stack

This paper describes a new architecture which addresses Quality of Service (QoS) by creating unique flows for applications, services, or subnets. A flow is a dedicated and independent path from the NIC hardware to the socket layer in which the QoS layer is integrated into the protocol stack instead of being implemented as a separate layer. Each flow has dedicated hardware and software resources allowing applications to meet their specified quality of service within the host. The architecture efficiently copes with Distributed Denial of Service (DDoS) attacks by creating zero or limited bandwidth flows for the attacking traffic. The unwanted packets can be dropped by the NIC hardware itself at no cost.A collection of flows on more than one host can be assigned the same Differentiated Services Code Point (DSCP) label which forms a path dedicated to a service across the enterprise network and enables end-to-end QoS within the data center.