Pub Date : 2005-03-13DOI: 10.1109/INFCOM.2005.1498527
M. Andrews, Lijun Qian, A. Stolyar
We consider the problem of scheduling multiple users sharing a time-varying wireless channel. (As an example, this is a model of scheduling in 3G wireless technologies, such as CDMA2000 3G1xEV-DO downlink scheduling.) We introduce an algorithm which seeks to optimize a concave utility function /spl Sigma//sub i/H/sub i/(R/sub i/) of the user throughputs R/sub i/, subject to certain lower and upper throughput bounds: R/sub i//sup min//spl les/R/sub i//spl les/R/sub i//sup max/. The algorithm, which we call the gradient algorithm with minimum/maximum rate constraints (GMR) uses a token counter mechanism, which modifies an algorithm solving the corresponding unconstrained problem, to produce the algorithm solving the problem with throughput constraints. Two important special cases of the utility functions are /spl Sigma//sub i/log R/sub i/ and /spl Sigma//sub i/R/sub i/, corresponding to the common proportional fairness and throughput maximization objectives. We study the dynamics of user throughputs under GMR algorithm, and show that GMR is asymptotically optimal in the following sense. If, under an appropriate scaling, the throughput vector R(t) converges to a fixed vector R/sup +/ as time t/spl rarr//spl infin/ then R/sup +/ is an optimal solution to the optimization problem described above. We also present simulation results showing the algorithm performance.
{"title":"Optimal utility based multi-user throughput allocation subject to throughput constraints","authors":"M. Andrews, Lijun Qian, A. Stolyar","doi":"10.1109/INFCOM.2005.1498527","DOIUrl":"https://doi.org/10.1109/INFCOM.2005.1498527","url":null,"abstract":"We consider the problem of scheduling multiple users sharing a time-varying wireless channel. (As an example, this is a model of scheduling in 3G wireless technologies, such as CDMA2000 3G1xEV-DO downlink scheduling.) We introduce an algorithm which seeks to optimize a concave utility function /spl Sigma//sub i/H/sub i/(R/sub i/) of the user throughputs R/sub i/, subject to certain lower and upper throughput bounds: R/sub i//sup min//spl les/R/sub i//spl les/R/sub i//sup max/. The algorithm, which we call the gradient algorithm with minimum/maximum rate constraints (GMR) uses a token counter mechanism, which modifies an algorithm solving the corresponding unconstrained problem, to produce the algorithm solving the problem with throughput constraints. Two important special cases of the utility functions are /spl Sigma//sub i/log R/sub i/ and /spl Sigma//sub i/R/sub i/, corresponding to the common proportional fairness and throughput maximization objectives. We study the dynamics of user throughputs under GMR algorithm, and show that GMR is asymptotically optimal in the following sense. If, under an appropriate scaling, the throughput vector R(t) converges to a fixed vector R/sup +/ as time t/spl rarr//spl infin/ then R/sup +/ is an optimal solution to the optimization problem described above. We also present simulation results showing the algorithm performance.","PeriodicalId":20482,"journal":{"name":"Proceedings IEEE 24th Annual Joint Conference of the IEEE Computer and Communications Societies.","volume":"229 1","pages":"2415-2424 vol. 4"},"PeriodicalIF":0.0,"publicationDate":"2005-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73936280","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-03-13DOI: 10.1109/INFCOM.2005.1498374
A. Ganesh, L. Massoulié, D. Towsley
Many network phenomena are well modeled as spreads of epidemics through a network. Prominent examples include the spread of worms and email viruses, and, more generally, faults. Many types of information dissemination can also be modeled as spreads of epidemics. In this paper we address the question of what makes an epidemic either weak or potent. More precisely, we identify topological properties of the graph that determine the persistence of epidemics. In particular, we show that if the ratio of cure to infection rates is larger than the spectral radius of the graph, then the mean epidemic lifetime is of order log n, where n is the number of nodes. Conversely, if this ratio is smaller than a generalization of the isoperimetric constant of the graph, then the mean epidemic lifetime is of order e/sup na/, for a positive constant a. We apply these results to several network topologies including the hypercube, which is a representative connectivity graph for a distributed hash table, the complete graph, which is an important connectivity graph for BGP, and the power law graph, of which the AS-level Internet graph is a prime example. We also study the star topology and the Erdos-Renyi graph as their epidemic spreading behaviors determine the spreading behavior of power law graphs.
许多网络现象可以很好地模拟为流行病通过网络的传播。突出的例子包括蠕虫和电子邮件病毒的传播，以及更普遍的故障。许多类型的信息传播也可以模拟为流行病的传播。在本文中，我们讨论是什么使流行病变弱或变强的问题。更准确地说，我们确定了决定流行病持久性的图的拓扑性质。特别地，我们证明了如果治愈率与感染率之比大于图的谱半径，则平均流行病寿命为log n阶，其中n为节点数。相反,如果这个比率小于泛化等周常数的图,顺序的流行一生是e / na /一同晚餐,积极的常数。我们将这些结果应用到几种网络拓扑包括超立方体,这是一个代表分布式哈希表连接图,完全图,这是一个重要的连接图边界网关协议,和幂律图,等级的网络图是一个典型的例子。我们还研究了星型拓扑和Erdos-Renyi图，因为它们的流行传播行为决定了幂律图的传播行为。
{"title":"The effect of network topology on the spread of epidemics","authors":"A. Ganesh, L. Massoulié, D. Towsley","doi":"10.1109/INFCOM.2005.1498374","DOIUrl":"https://doi.org/10.1109/INFCOM.2005.1498374","url":null,"abstract":"Many network phenomena are well modeled as spreads of epidemics through a network. Prominent examples include the spread of worms and email viruses, and, more generally, faults. Many types of information dissemination can also be modeled as spreads of epidemics. In this paper we address the question of what makes an epidemic either weak or potent. More precisely, we identify topological properties of the graph that determine the persistence of epidemics. In particular, we show that if the ratio of cure to infection rates is larger than the spectral radius of the graph, then the mean epidemic lifetime is of order log n, where n is the number of nodes. Conversely, if this ratio is smaller than a generalization of the isoperimetric constant of the graph, then the mean epidemic lifetime is of order e/sup na/, for a positive constant a. We apply these results to several network topologies including the hypercube, which is a representative connectivity graph for a distributed hash table, the complete graph, which is an important connectivity graph for BGP, and the power law graph, of which the AS-level Internet graph is a prime example. We also study the star topology and the Erdos-Renyi graph as their epidemic spreading behaviors determine the spreading behavior of power law graphs.","PeriodicalId":20482,"journal":{"name":"Proceedings IEEE 24th Annual Joint Conference of the IEEE Computer and Communications Societies.","volume":"6 1","pages":"1455-1466 vol. 2"},"PeriodicalIF":0.0,"publicationDate":"2005-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74715687","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-03-13DOI: 10.1109/INFCOM.2005.1498462
N. Fonseca, M. Crovella
One of TCP's critical tasks is to determine which packets are lost in the network, as a basis for control actions (flow control and packet retransmission). Modern TCP implementations use two mechanisms: timeout, and fast retransmit. Detection via timeout is necessarily a time-consuming operation; fast retransmit, while much quicker, is only effective for a small fraction of packet losses. In this paper we consider the problem of packet loss detection in TCP more generally. We concentrate on the fact that TCP's control actions are necessarily triggered by inference of packet loss, rather than conclusive knowledge. This suggests that one might analyze TCP's packet loss detection in a standard inferencing framework based on probability of detection and probability of false alarm. This paper makes two contributions to that end: first, we study an example of more general packet loss inference, namely optimal Bayesian packet loss detection based on round trip time. We show that for long-lived flows, it is frequently possible to achieve high detection probability and low false alarm probability based on measured round trip time. Second, we construct an analytic performance model that incorporates general packet loss inference into TCP. We show that for realistic detection and false alarm probabilities (as are achievable via our Bayesian detector) and for moderate packet loss rates, the use of more general packet loss inference in TCP can improve throughput by as much as 25%.
{"title":"Bayesian packet loss detection for TCP","authors":"N. Fonseca, M. Crovella","doi":"10.1109/INFCOM.2005.1498462","DOIUrl":"https://doi.org/10.1109/INFCOM.2005.1498462","url":null,"abstract":"One of TCP's critical tasks is to determine which packets are lost in the network, as a basis for control actions (flow control and packet retransmission). Modern TCP implementations use two mechanisms: timeout, and fast retransmit. Detection via timeout is necessarily a time-consuming operation; fast retransmit, while much quicker, is only effective for a small fraction of packet losses. In this paper we consider the problem of packet loss detection in TCP more generally. We concentrate on the fact that TCP's control actions are necessarily triggered by inference of packet loss, rather than conclusive knowledge. This suggests that one might analyze TCP's packet loss detection in a standard inferencing framework based on probability of detection and probability of false alarm. This paper makes two contributions to that end: first, we study an example of more general packet loss inference, namely optimal Bayesian packet loss detection based on round trip time. We show that for long-lived flows, it is frequently possible to achieve high detection probability and low false alarm probability based on measured round trip time. Second, we construct an analytic performance model that incorporates general packet loss inference into TCP. We show that for realistic detection and false alarm probabilities (as are achievable via our Bayesian detector) and for moderate packet loss rates, the use of more general packet loss inference in TCP can improve throughput by as much as 25%.","PeriodicalId":20482,"journal":{"name":"Proceedings IEEE 24th Annual Joint Conference of the IEEE Computer and Communications Societies.","volume":"8 1","pages":"1826-1837 vol. 3"},"PeriodicalIF":0.0,"publicationDate":"2005-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73572651","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-03-13DOI: 10.1109/INFCOM.2005.1498538
J. Herdtner, E. Chong
Gupta and Kumar (2000) showed that the throughput capacity of static ad hoc networks with n randomly positioned nodes is /spl Theta/(/spl radic/(n/log n)). Grossglauser and Tse showed that node mobility increases the capacity to /spl Theta/(n), a substantial improvement. Achieving maximum capacity requires nodes to relay transmissions through other nodes. Each node must have a relay buffer for temporarily storing packets before forwarding them to their destination. We establish that if relay buffer sizes are bounded above by a constant, then mobility does not substantially increase the throughput capacity of mobile ad hoc networks. In particular, we show that the capacity of mobile networks with finite buffers is at most /spl Theta/(/spl radic/n). Finally we establish a scaling law relationship that characterizes the fundamental tradeoff between throughput capacity and relay buffer size. In particular, we show that the throughput capacity is at most /spl Theta/(/spl radic/(nb/sub n/)), where b/sub n/ is the size of the relay buffers.
{"title":"Throughput-storage tradeoff in ad hoc networks","authors":"J. Herdtner, E. Chong","doi":"10.1109/INFCOM.2005.1498538","DOIUrl":"https://doi.org/10.1109/INFCOM.2005.1498538","url":null,"abstract":"Gupta and Kumar (2000) showed that the throughput capacity of static ad hoc networks with n randomly positioned nodes is /spl Theta/(/spl radic/(n/log n)). Grossglauser and Tse showed that node mobility increases the capacity to /spl Theta/(n), a substantial improvement. Achieving maximum capacity requires nodes to relay transmissions through other nodes. Each node must have a relay buffer for temporarily storing packets before forwarding them to their destination. We establish that if relay buffer sizes are bounded above by a constant, then mobility does not substantially increase the throughput capacity of mobile ad hoc networks. In particular, we show that the capacity of mobile networks with finite buffers is at most /spl Theta/(/spl radic/n). Finally we establish a scaling law relationship that characterizes the fundamental tradeoff between throughput capacity and relay buffer size. In particular, we show that the throughput capacity is at most /spl Theta/(/spl radic/(nb/sub n/)), where b/sub n/ is the size of the relay buffers.","PeriodicalId":20482,"journal":{"name":"Proceedings IEEE 24th Annual Joint Conference of the IEEE Computer and Communications Societies.","volume":"8 1","pages":"2536-2542 vol. 4"},"PeriodicalIF":0.0,"publicationDate":"2005-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75449509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-03-13DOI: 10.1109/INFCOM.2005.1498526
A. Kamra, Hanhua Feng, V. Misra, A. Keromytis
It is a commonly held belief that IPv6 provides greater security against random-scanning worms by virtue of a very sparse address space. We show that an intelligent worm can exploit the directory and naming services necessary for the functioning of any network, and we model the behavior of such a worm in this paper. We explore via analysis and simulation the spread of such worms in an IPv6 Internet. Our results indicate that such a worm can exhibit propagation speeds comparable to an IPv4 random-scanning worm. We develop a detailed analytical model that reveals the relationship between network parameters and the spreading rate of the worm in an IPv6 world. We also develop a simulator based on our analytical model. Simulation results based on parameters chosen from real measurements and the current Internet indicate that an intelligent worm can spread surprising fast in an IPv6 world by using simple strategies. The performance of the worm depends heavily on these strategies, which in turn depend on how secure the directory and naming services of a network are. As a result, additional work is needed in developing detection and defense mechanisms against future worms, and our work identifies directory and naming services as the natural place to do it.
{"title":"The effect of DNS delays on worm propagation in an IPv6 Internet","authors":"A. Kamra, Hanhua Feng, V. Misra, A. Keromytis","doi":"10.1109/INFCOM.2005.1498526","DOIUrl":"https://doi.org/10.1109/INFCOM.2005.1498526","url":null,"abstract":"It is a commonly held belief that IPv6 provides greater security against random-scanning worms by virtue of a very sparse address space. We show that an intelligent worm can exploit the directory and naming services necessary for the functioning of any network, and we model the behavior of such a worm in this paper. We explore via analysis and simulation the spread of such worms in an IPv6 Internet. Our results indicate that such a worm can exhibit propagation speeds comparable to an IPv4 random-scanning worm. We develop a detailed analytical model that reveals the relationship between network parameters and the spreading rate of the worm in an IPv6 world. We also develop a simulator based on our analytical model. Simulation results based on parameters chosen from real measurements and the current Internet indicate that an intelligent worm can spread surprising fast in an IPv6 world by using simple strategies. The performance of the worm depends heavily on these strategies, which in turn depend on how secure the directory and naming services of a network are. As a result, additional work is needed in developing detection and defense mechanisms against future worms, and our work identifies directory and naming services as the natural place to do it.","PeriodicalId":20482,"journal":{"name":"Proceedings IEEE 24th Annual Joint Conference of the IEEE Computer and Communications Societies.","volume":"1 1","pages":"2405-2414 vol. 4"},"PeriodicalIF":0.0,"publicationDate":"2005-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77287400","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-03-13DOI: 10.1109/INFCOM.2005.1498452
I. Keslassy, Cheng-Shang Chang, N. McKeown, D. Lee
This paper is about load-balancing packets across multiple paths inside a switch, or across a network. It is motivated by the recent interest in load-balanced switches. Load-balanced switches provide an appealing alternative to crossbars with centralized schedulers. A load-balanced switch has no scheduler, is particularly amenable to optics, and - most relevant here -guarantees 100% throughput. A uniform mesh is used to load-balance packets uniformly across all 2-hop paths in the switch. In this paper we explore whether this particular method of load-balancing is optimal in the sense that it achieves the highest throughput for a given capacity of interconnect. The method we use allows the load-balanced switch to be compared with ring, torus and hypercube interconnects, too. We prove that for a given interconnect capacity, the load-balancing mesh has the maximum throughput. Perhaps surprisingly, we find that the best mesh is slightly non-uniform, or biased, and has a throughput of N/(2N - 1), where N is the number of nodes.
{"title":"Optimal load-balancing","authors":"I. Keslassy, Cheng-Shang Chang, N. McKeown, D. Lee","doi":"10.1109/INFCOM.2005.1498452","DOIUrl":"https://doi.org/10.1109/INFCOM.2005.1498452","url":null,"abstract":"This paper is about load-balancing packets across multiple paths inside a switch, or across a network. It is motivated by the recent interest in load-balanced switches. Load-balanced switches provide an appealing alternative to crossbars with centralized schedulers. A load-balanced switch has no scheduler, is particularly amenable to optics, and - most relevant here -guarantees 100% throughput. A uniform mesh is used to load-balance packets uniformly across all 2-hop paths in the switch. In this paper we explore whether this particular method of load-balancing is optimal in the sense that it achieves the highest throughput for a given capacity of interconnect. The method we use allows the load-balanced switch to be compared with ring, torus and hypercube interconnects, too. We prove that for a given interconnect capacity, the load-balancing mesh has the maximum throughput. Perhaps surprisingly, we find that the best mesh is slightly non-uniform, or biased, and has a throughput of N/(2N - 1), where N is the number of nodes.","PeriodicalId":20482,"journal":{"name":"Proceedings IEEE 24th Annual Joint Conference of the IEEE Computer and Communications Societies.","volume":"113 1","pages":"1712-1722 vol. 3"},"PeriodicalIF":0.0,"publicationDate":"2005-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84930791","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-03-13DOI: 10.1109/INFCOM.2005.1498322
Shirin Ebrahimi-Taghizadeh, A. Helmy, S. Gupta
This paper describes systematical development of TCP adversarial scenarios where we use short-lived TCP flows to adversely influence long-lived TCP flows. Our scenarios are interesting since, (a) they point out the increased vulnerabilities of recently proposed scheduling, AQM and routing techniques that further favor short-lived TCP flows and (b) they are more difficult to detect when intentionally found to target long-lived TCP flows. We systematically exploit the ability of TCP flows in slow-start to rapidly capture greater proportion of bandwidth compared to long-lived TCP flows in congestion avoidance phase, to a point where they drive long-lived TCP flows into timeout. We use simulations, analysis and experiments to systematically study the dependence of the severity of impact on long-lived TCP flows on key parameters of short-lived TCP flows-including their locations, durations and numbers, as well as the intervals between consecutive flows. We derive characteristics of pattern of short-lived flows that exhibit extreme adverse impact on long-lived TCP flows. Counter to common beliefs, we show that targeting bottleneck links does not always cause maximal performance degradation for the long-lived flows. In particular, our approach illustrates the interactions between TCP flows and multiple bottleneck links and their sensitivities to correlated losses in the absence of 'non-TCP friendly' flows and paves the way for a systematic synthesis of worst-case congestion scenarios. While randomly generated sequences of short-lived TCP flows may provide some reductions (up to 10%) in the throughput of the long-lived flows, the scenarios we generate cause much greater reductions (>85%) for several TCP variants and for different packet drop policies (DropTail, RED).
{"title":"TCP vs. TCP: a systematic study of adverse impact of short-lived TCP flows on long-lived TCP flows","authors":"Shirin Ebrahimi-Taghizadeh, A. Helmy, S. Gupta","doi":"10.1109/INFCOM.2005.1498322","DOIUrl":"https://doi.org/10.1109/INFCOM.2005.1498322","url":null,"abstract":"This paper describes systematical development of TCP adversarial scenarios where we use short-lived TCP flows to adversely influence long-lived TCP flows. Our scenarios are interesting since, (a) they point out the increased vulnerabilities of recently proposed scheduling, AQM and routing techniques that further favor short-lived TCP flows and (b) they are more difficult to detect when intentionally found to target long-lived TCP flows. We systematically exploit the ability of TCP flows in slow-start to rapidly capture greater proportion of bandwidth compared to long-lived TCP flows in congestion avoidance phase, to a point where they drive long-lived TCP flows into timeout. We use simulations, analysis and experiments to systematically study the dependence of the severity of impact on long-lived TCP flows on key parameters of short-lived TCP flows-including their locations, durations and numbers, as well as the intervals between consecutive flows. We derive characteristics of pattern of short-lived flows that exhibit extreme adverse impact on long-lived TCP flows. Counter to common beliefs, we show that targeting bottleneck links does not always cause maximal performance degradation for the long-lived flows. In particular, our approach illustrates the interactions between TCP flows and multiple bottleneck links and their sensitivities to correlated losses in the absence of 'non-TCP friendly' flows and paves the way for a systematic synthesis of worst-case congestion scenarios. While randomly generated sequences of short-lived TCP flows may provide some reductions (up to 10%) in the throughput of the long-lived flows, the scenarios we generate cause much greater reductions (>85%) for several TCP variants and for different packet drop policies (DropTail, RED).","PeriodicalId":20482,"journal":{"name":"Proceedings IEEE 24th Annual Joint Conference of the IEEE Computer and Communications Societies.","volume":"7 1","pages":"926-937 vol. 2"},"PeriodicalIF":0.0,"publicationDate":"2005-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85587052","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-03-13DOI: 10.1109/INFCOM.2005.1498450
Ningning Hu, Erran L. Li, Z. Morley Mao, P. Steenkiste, Jia Wang
Recent advances in Internet measurement tools have made it possible to locate bottleneck links that constrain the available bandwidth of Internet paths. In this paper, we provide a detailed study of Internet path bottlenecks. We focus on the following four aspects: the persistence of bottleneck location, the sharing of bottlenecks among destination clusters, the packet loss and queueing delay of bottleneck links, and the relationship with router and link properties, including router CPU load, router memory load, link traffic load, and link capacity. We find that 20% - 30% of the source-destination pairs in our measurement have a persistent bottleneck; fewer than 10% of the destinations in a prefix cluster share a bottleneck more than half of the time; 60% of the bottlenecks on lossy paths can be correlated with a loss point no more than 2 hops away; and bottlenecks can be clearly correlated with link load, while presenting no strong relationship with link capacity, router CPU and memory load.
{"title":"A measurement study of Internet bottlenecks","authors":"Ningning Hu, Erran L. Li, Z. Morley Mao, P. Steenkiste, Jia Wang","doi":"10.1109/INFCOM.2005.1498450","DOIUrl":"https://doi.org/10.1109/INFCOM.2005.1498450","url":null,"abstract":"Recent advances in Internet measurement tools have made it possible to locate bottleneck links that constrain the available bandwidth of Internet paths. In this paper, we provide a detailed study of Internet path bottlenecks. We focus on the following four aspects: the persistence of bottleneck location, the sharing of bottlenecks among destination clusters, the packet loss and queueing delay of bottleneck links, and the relationship with router and link properties, including router CPU load, router memory load, link traffic load, and link capacity. We find that 20% - 30% of the source-destination pairs in our measurement have a persistent bottleneck; fewer than 10% of the destinations in a prefix cluster share a bottleneck more than half of the time; 60% of the bottlenecks on lossy paths can be correlated with a loss point no more than 2 hops away; and bottlenecks can be clearly correlated with link load, while presenting no strong relationship with link capacity, router CPU and memory load.","PeriodicalId":20482,"journal":{"name":"Proceedings IEEE 24th Annual Joint Conference of the IEEE Computer and Communications Societies.","volume":"36 1","pages":"1689-1700 vol. 3"},"PeriodicalIF":0.0,"publicationDate":"2005-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85863405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-03-13DOI: 10.1109/INFCOM.2005.1498339
A. Srivastava, S. Acharya, M. Alicherry, B. Gupta, P. Risbood
The virtual concatenation protocol in SONET/SDH has ushered in a novel routing paradigm that enables a circuit to be "split" and routed over multiple paths. However, this diverse routing causes differential delay among the paths which can impact service if not accounted for in the routing. In this paper, we introduce the differential delay aware routing problem and show that it is not only NP-complete but is also provably hard to approximate within a constant factor. However, by transforming it into a flow routing formulation, we can derive effective, practical solutions. We present various algorithms and use extensive simulations to show that they are a good match to an "ideal" integer linear programming formulation. We also highlight how the differential delay data allows individual link delays to be reverse-engineered. We propose three algorithms to derive link delays including one that leverages the flexibility in the virtual concatenation protocol bits. Given the rise of next-generation applications such as online games where latency information is key, this knowledge of link delays, heretofore only loosely approximated, enables the telecom infrastructure to be more effective in supporting these applications.
{"title":"Differential delay aware routing for Ethernet over SONET/SDH","authors":"A. Srivastava, S. Acharya, M. Alicherry, B. Gupta, P. Risbood","doi":"10.1109/INFCOM.2005.1498339","DOIUrl":"https://doi.org/10.1109/INFCOM.2005.1498339","url":null,"abstract":"The virtual concatenation protocol in SONET/SDH has ushered in a novel routing paradigm that enables a circuit to be \"split\" and routed over multiple paths. However, this diverse routing causes differential delay among the paths which can impact service if not accounted for in the routing. In this paper, we introduce the differential delay aware routing problem and show that it is not only NP-complete but is also provably hard to approximate within a constant factor. However, by transforming it into a flow routing formulation, we can derive effective, practical solutions. We present various algorithms and use extensive simulations to show that they are a good match to an \"ideal\" integer linear programming formulation. We also highlight how the differential delay data allows individual link delays to be reverse-engineered. We propose three algorithms to derive link delays including one that leverages the flexibility in the virtual concatenation protocol bits. Given the rise of next-generation applications such as online games where latency information is key, this knowledge of link delays, heretofore only loosely approximated, enables the telecom infrastructure to be more effective in supporting these applications.","PeriodicalId":20482,"journal":{"name":"Proceedings IEEE 24th Annual Joint Conference of the IEEE Computer and Communications Societies.","volume":"08 1","pages":"1117-1127 vol. 2"},"PeriodicalIF":0.0,"publicationDate":"2005-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85980564","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-03-13DOI: 10.1109/INFCOM.2005.1498556
Pradipta De, Ashish Raniwala, Srikant Sharma, T. Chiueh
Most mobile wireless networking research today relies on simulations. However, fidelity of simulation results has always been a concern, especially when the protocols being studied are affected by the propagation and interference characteristics of the radio channels. Inherent difficulty in faithfully modeling the wireless channel characteristics has encouraged several researchers to build wireless network testbeds. A full-fledged wireless testbed is spread over a large physical space because of the wide coverage area of radio signals. This makes a large-scale testbed difficult and expensive to set up, configure, and manage. This paper describes a miniaturized 802.11b-based, multi-hop wireless network testbed called MiNT. MiNT occupies a significantly small space, and dramatically reduces the efforts required in setting up a multi-hop wireless network used for wireless application/protocol testing and evaluation. MiNT is also a hybrid simulation platform that can execute ns-2 simulation scripts with the link, MAC and physical layer in the simulator replaced by real hardware. We demonstrate the fidelity of MiNT by comparing experimental results on it with similar experiments conducted on a non-miniaturized testbed. We also compare the results of experiments conducted using hybrid simulation on MiNT with those obtained using pure simulation. Finally, using a case study we show the usefulness of MiNT in wireless application testing and evaluation.
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