In this paper, we show that it is possible to use overlay networks to
enhance Internet QoS without any support from the underlying IP
network. Using two real-world applications and experiments over a
wide-area testbed we demonstrate three such QoS enhancements: (a)
smoothing losses; (b) prioritization of packets within an aggregate;
(c) statistical loss and bandwidth guarantees. OverQoS is able to
achieve all these enhancements with little (i.e.,
) or no extra
bandwidth overhead.
While our results suggest that OverQoS can be a viable architecture to enhance the Internet QoS, more remains to be done. Our current solution assumes that the flows' paths at the OverQoS level are predetermined. A natural extension would be to combine admission control and path selection, e.g., to have the entry OverQoS node compute the ``best'' path that satisfies a flow's requirements at the admission time. One possibility would be to use RON [32] to find paths with better performance characteristics and to recover from network failures. Another interesting problem would be to determine the ``optimal'' placement of the OverQoS nodes in the network. We intend to address these issues as part of future work.