@article{vishwanath_sivaraman_rouskas_2011, title={Anomalous Loss Performance for Mixed Real-Time and TCP Traffic in Routers With Very Small Buffers}, volume={19}, ISSN={["1558-2566"]}, DOI={10.1109/tnet.2010.2091721}, abstractNote={In the past few years there has been vigorous debate regarding the size of buffers required at core Internet routers. Recent arguments supported by theory and experimentation show that under certain conditions, core router buffer sizes of a few tens of packets suffice for realizing acceptable end-to-end TCP throughputs. This is a significant step toward the realization of optical packet switched (OPS) networks, which are inherently limited in their ability to buffer optical signals. However, prior studies have largely ignored the presence of real-time traffic, which is increasing in importance as a source of revenue for Internet service providers. In this paper, we study the interaction that happens between real-time (open-loop) and TCP (closed-loop) traffic when they multiplex at buffers of very small size (few tens of packets) and make a significant discovery - namely that in a specific range of buffer size, real-time traffic losses increase as buffer size becomes larger. Our contributions pertaining to this anomalous behavior are threefold. First, we exhibit this anomalous loss performance for real-time traffic via extensive simulations using synthetic traffic and real video traces. Second, we develop quantitative models that reveal the dynamics of buffer sharing between real-time and TCP traffic that lead to this behavior. Third, we show how various factors such as the nature of real-time traffic, mixture of long-lived and short-lived TCP flows, and packet sizes impact the severity of the anomaly. Our study is the first to consider interactions between real-time and TCP traffic in very small (potentially all-optical) buffers and informs router manufacturers and network operators of the factors to consider when dimensioning such small buffer sizes for desired performance balance between real-time and TCP traffic.}, number={4}, journal={IEEE-ACM TRANSACTIONS ON NETWORKING}, author={Vishwanath, Arun and Sivaraman, Vijay and Rouskas, George N.}, year={2011}, month={Aug}, pages={933–946} }
@article{sivaraman_rouskas_2000, title={A reservation protocol for broadcast WDM networks and stability analysis}, volume={32}, ISSN={["1872-7069"]}, DOI={10.1016/s1389-1286(99)00137-1}, abstractNote={We consider the problem of coordinating access to the various channels of a single-hop wavelength division multiplexing (WDM) network. We present a high performance reservation (HiPeR-ℓ) protocol specifically designed to overcome the potential inefficiencies of operating in environments with non-negligible processing, tuning, and propagation delays. HiPeR-ℓ differs from previous reservation protocols in that each control packet makes reservations for all data packets waiting in a node's queues, thus significantly reducing control overhead. Packets are scheduled for transmission using algorithms that can effectively mask the tuning times. HiPeR-ℓ also uses pipelining to mask processing times and propagation delays; parameter ℓ of the protocol is used to control the degree of pipelining. We use Markov chain theory to obtain a sufficient condition for the stability of the protocol. The stability condition provides insight into the factors affecting the operation of the protocol, such as the degree of load balancing across the various channels, and the quality of the scheduling algorithms. The analysis is fairly general, as it holds for MMBP-like arrival processes with any number of states, and for non-uniform destinations.}, number={2}, journal={COMPUTER NETWORKS}, author={Sivaraman, V and Rouskas, GN}, year={2000}, month={Feb}, pages={211–227} }
@article{nolan_sivaraman_savage_tiwari_1998, title={Graphical basis partitions}, volume={14}, ISSN={["0911-0119"]}, DOI={10.1007/s003730050029}, abstractNote={A partition of an integer n is graphical if it is the degree sequence of a simple, undirected graph. It is an open question whether the fraction of partitions of n which are graphical approaches 0 as n approaches infinity. A partition π is basic if the number of dots in its Ferrers graph is minimum among all partitions with the same rank vector as π. In this paper, we investigate graphical partitions via basis partitions. We show how to efficiently count and generate graphical basis partitions and how to use them to count graphical partitions. We give empirical evidence which leads us to conjecture that, as n approaches infinity, the fraction of basis partitions of n which are graphical approaches the same limit as the fraction of all partitions of n which are graphical.}, number={3}, journal={GRAPHS AND COMBINATORICS}, author={Nolan, JM and Sivaraman, V and Savage, CD and Tiwari, PK}, year={1998}, pages={241–261} }
@article{rouskas_sivaraman_1997, title={Packet scheduling in broadcast WDM networks with arbitrary transceiver tuning latencies}, volume={5}, ISSN={["1558-2566"]}, DOI={10.1109/90.611101}, abstractNote={We consider the problem of scheduling packet transmissions in a broadcast, single-hop wavelength-division multiplexing (WDM) network, with tunability provided only at one end. Our objective is to design schedules of minimum length to satisfy a set of traffic requirements given in the form of a demand matrix. We address a fairly general version of the problem as we allow arbitrary traffic demands and arbitrary transmitter tuning latencies. The contribution of our work is twofold, First we define a special class of schedules which permit an intuitive formulation of the scheduling problem. Based on this formulation we present algorithms which construct schedules of length equal to the lower bound provided that the traffic requirements satisfy certain optimality conditions. We also develop heuristics which, in the general case, give schedules of length equal or very close to the lower bound. Secondly, we identify two distinct regions of network operation. The first region is such that the schedule length is determined by the tuning requirements of transmitters; when the network operates within the second region however, the length of the schedule is determined by the traffic demands, not the tuning latency. The point at which the network switches between the two regions is identified in terms of system parameters such as the number of nodes and channels and the tuning latency. Accordingly, we show that it is possible to appropriately dimension the network to minimize the effects of even large values of the tuning latency.}, number={3}, journal={IEEE-ACM TRANSACTIONS ON NETWORKING}, author={Rouskas, GN and Sivaraman, V}, year={1997}, month={Jun}, pages={359–370} }