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[Winstein-Balakrishnan-2011 (doi) .]
K. Winstein, H. Balakrishnan
“End-to-End Transmission Control by Modeling Uncertainty about the Network State”,
HotNets-X , Cambridge, MA, November 2011
ResiliNets Keywords: TCP Transmission Control
Keywords: Design, Performance, TCP
Abstract: “This paper argues that the bar for the incorporation of a new subnetwork or link technology in the current Internet is much more than the ability to send minimum-sized IP packets: success requires that TCP perform well over any subnetwork. This requirement imposes a number of additional constraints, some hard to meet because TCP’s network model is limited and its overall objective challenging to specify precisely. As a result, network evolution has been hampered and the potential of new subnetwork technologies has not been realized in practice. The poor end-to-end performance of many important subnetworks, such as wide-area cellular networks that zealously hide non-congestive losses and introduce enormous delays as a result, or home broadband networks that suffer from the notorious “bufferbloat” problem, are symptoms of this more general issue.
We propose an alternate architecture for end-to-end resource management and transmission control, in which the endpoints work directly to achieve a speci?ed goal. Each endpoint treats the network as an nondeterministic automaton whose parameters and topology are uncertain. The endpoint maintains a probability distribution on what it thinks the network’s con?guration may be. At each moment, the endpoint acts to maximize the expected value of a utility function that is given explicitly. We present preliminary simulation results arguing that the approach is tractable and holds promise ”
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[Li-Lukyanenko-Cui-2012 (doi) .]
M. Li, A. Lukyanenko, Y. Cui
“Network coding based multipath TCP”,
2012 IEEE Conference on Computer Communications Workshops (INFOCOM WKSHPS) , vol., no., pp.25-30, 25-30 March 2012
ResiliNets Keywords: Multipath TCP, Network Coding
Keywords: NC subflow , NC-MPTCP , NS-3 network simulator , data allocation , diverse network condition , multipath TCP protocol , multipath transfer , network coding , packet scheduling algorithm , redundancy estimation algorithm , regular subflow , subflow qualities
Abstract: “Multipath TCP (MPTCP) suffers from the degradation of goodput in the presence of diverse network conditions on the available subflows. The goodput can even be worse than that of one regular TCP, undermining the advantage gained by using multipath transfer. In this work, we propose a new multipath TCP protocol, namely NC-MPTCP, which introduces network coding (NC) to some but not all subflows traveling from source to destination. At the core of our scheme is the mixed use of regular and NC subflows. Thus, the regular subflows deliver original data while the NC subflows deliver linear combinations of the original data. The idea is to take advantage of the redundant NC data to compensate for the lost or delayed data in order to avoid receive buffer becoming full. We design a packet scheduling algorithm and a redundancy estimation algorithm to allocate data among different subflows in order to optimize the overall goodput. We also give a guideline on how to choose the NC subflows among the available subflows. We evaluate the performance of NC-MPTCP through a NS-3 network simulator. The experiments show that NC-MPTCP achieves higher goodput compared to MPTCP in the presence of different subflow qualities. And in the worst case, the performance of NC-MPTCP is close to that of one regular TCP.”
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[Sundararajan-Shar-medard-Jakubczak-Mitzenmacher-Barros-2011 (doi).]
J.K. Sundararajan, D. Shah, M. Medard, S. Jakubczak, M. Mitzenmacher, J. Barros
“Network Coding Meets TCP: Theory and Implementation”,
Proceedings of the IEEE , vol.99, no.3, pp.490-512, March 2011
ResiliNets Keywords: TCP, Network Coding
Keywords: TCP , TCP-NC , acknowledgment-based flow control , batch-based coding , congestion control , congestion window , lossy network , multicast scenario , multipath scenario , network coding , packet reencoding , protocol stack , sliding window mechanism , transmission control protocol , window management mechanism , wireless links , wireless network
Abstract: “The theory of network coding promises significant benefits in network performance, especially in lossy networks and in multicast and multipath scenarios. To realize these benefits in practice, we need to understand how coding across packets interacts with the acknowledgment (ACK)-based flow control mechanism that forms a central part of today's Internet protocols such as transmission control protocol (TCP). Current approaches such as rateless codes and batch-based coding are not compatible with TCP's retransmission and sliding-window mechanisms. In this paper, we propose a new mechanism called TCP/NC that incorporates network coding into TCP with only minor changes to the protocol stack, thereby allowing incremental deployment. In our scheme, the source transmits random linear combinations of packets currently in the congestion window. At the heart of our scheme is a new interpretation of ACKs-the sink acknowledges every degree of freedom (i.e., a linear combination that reveals one unit of new information) even if it does not reveal an original packet immediately. Thus, our new TCP ACK rule takes into account the network coding operations in the lower layer and enables a TCP-compatible sliding-window approach to network coding. Coding essentially masks losses from the congestion control algorithm and allows TCP/NC to react smoothly to losses, resulting in a novel and effective approach for congestion control over lossy networks such as wireless networks. An important feature of our solution is that it allows intermediate nodes to perform re-encoding of packets, which is known to provide significant throughput gains in lossy networks and multicast scenarios. Simulations show that our scheme, with or without re-encoding inside the network, achieves much higher throughput compared to TCP over lossy wireless links. We present a real-world implementation of this protocol that addresses the practical aspects of incorporating network coding and decoding with TCP's wind ow management mechanism. We work with TCP-Reno, which is a widespread and practical variant of TCP. Our implementation significantly advances the goal of designing a deployable, general, TCP-compatible protocol that provides the benefits of network coding.”
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[Nichols-Jacobson-2012 (doi) .]
K. Nichols and V. Jacobson
“Controlling Queue Delay”,
ACM Queue - Networks , Volume 10 Issue 5, May 2012
ResiliNets Keywords: Congestion, Bufferbloat, Router buffer sizing
Keywords: Congestion, Bufferbloat, Router buffer sizing
Abstract: “Nearly three decades after it was first diagnosed, the “persistently full buffer problem,” recently exposed as part of bufferbloat,6,7 is still with us and made increasingly critical by two trends. First, cheap memory and a “more is better” mentality have led to the inflation and proliferation of buffers. Second, dynamically varying path characteristics are much more common today and are the norm at the consumer Internet edge. Reasonably sized buffers become extremely oversized when link rates and path delays fall below nominal values. The solution for persistently full buffers, AQM (active queue management), has been known for two decades but has not been widely deployed because of implementation difficulties and general misunderstanding about Internet packet loss and queue dynamics. Unmanaged buffers are more critical today since buffer sizes are larger, delay-sensitive applications are more prevalent, and large (streaming) downloads common. The continued existence of extreme delays at the Internet’s edge can impact its usefulness and hamper the growth of new applications. This article aims to provide part of the bufferbloat solution, proposing an innovative approach to AQM suitable for today’s Internet called CoDel (for Controlled Delay, pronounced like “coddle”). This is a “no-knobs” AQM that adapts to changing link rates and is suitable for deployment and experimentation in Linux-based routers (as well as silicon).”
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