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NetReplay: a new network primitive

In this paper, we describe Net-Replay, a new network primitive to help application end points conduct in-band characterization of the glitches they encountered. In Net-Replay, each network infrastructure element remembers a small amount of information for every packet observed at the element over a certain time interval. Furthermore, network elements expose a simple "packet marking" interface, using which they can indicate to end-points whether or not they had seen a particular packet in the past. When application end-points observe glitches, they replay (i.e. retransmit) the packets which observed the glitch and leverage feedback from network elements to determine the type and location of the glitch encountered by the packets. We discuss how end-host network stacks should be modified to leverage Net-Replay in this fashion. We also consider how network infrastructure can support Net-Replay in a lowoverhead fashion.
 We argue that Net-Replay can enable applications to detect a variety of glitches and react to them in an accurate and informed manner, while ensuring that the infrastructure stays simple and fast. We believe that proactive support from the network in the form of Net-Replay-like functionality is crucial to ensure robust performance of future Internet applications, many of which are likely to be highly demanding and far less tolerant of network glitches than traditional applications.