Pub Date : 2003-11-04DOI: 10.1109/ICNP.2003.1249779
S. Tilak, A. Murphy, W. Heinzelman, N. Abu-Ghazaleh
Future smart environments are characterized by multiple nodes that sense, collect, and disseminate information about environmental phenomena through a wireless network. In this paper, we define a set of applications that require a new form of distributed knowledge about the environment, referred to as non-uniform information granularity. By non-uniform information granularity we mean that the required accuracy or precision of information is proportional to the distance between a source node (information producer) and current sink node (information consumer). That is, as the distance between the source node and sink node increases, loss in information precision is acceptable. Applications that can benefit from this type of knowledge range from battlefield scenarios to rescue operations. The main objectives of this paper are two-fold: first, we precisely define non-uniform information granularity, and second we describe the different protocols that achieve non-uniform information dissemination and analyze these protocols based on complexity, energy consumption, and accuracy of information.
{"title":"Non-uniform information dissemination for sensor networks","authors":"S. Tilak, A. Murphy, W. Heinzelman, N. Abu-Ghazaleh","doi":"10.1109/ICNP.2003.1249779","DOIUrl":"https://doi.org/10.1109/ICNP.2003.1249779","url":null,"abstract":"Future smart environments are characterized by multiple nodes that sense, collect, and disseminate information about environmental phenomena through a wireless network. In this paper, we define a set of applications that require a new form of distributed knowledge about the environment, referred to as non-uniform information granularity. By non-uniform information granularity we mean that the required accuracy or precision of information is proportional to the distance between a source node (information producer) and current sink node (information consumer). That is, as the distance between the source node and sink node increases, loss in information precision is acceptable. Applications that can benefit from this type of knowledge range from battlefield scenarios to rescue operations. The main objectives of this paper are two-fold: first, we precisely define non-uniform information granularity, and second we describe the different protocols that achieve non-uniform information dissemination and analyze these protocols based on complexity, energy consumption, and accuracy of information.","PeriodicalId":179873,"journal":{"name":"11th IEEE International Conference on Network Protocols, 2003. Proceedings.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126814999","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 : 2003-11-04DOI: 10.1109/ICNP.2003.1249777
Chiping Tang, P. McKinley
Path probing is essential to maintaining an efficient overlay network topology. However, the cost of a full-scale probing is as high as O(n/sup 2/), which is prohibitive in large-scale overlay networks. Several methods have been proposed to reduce probing overhead, although at a cost in terms of probing completeness. In this paper, an orthogonal solution is proposed that trades probing overhead for estimation accuracy in sparse networks such as the Internet. The proposed solution uses network-level path composition information (for example, as provided by a topology server) to infer path quality without full-scale probing. The inference metrics include latency, loss rate and available bandwidth. This approach is used to design several probing algorithms, which are evaluated through analysis and simulation. The results show that the proposed method can significantly reduce probing overhead while providing hounded quality estimations for all n /spl times/ (n - 1) overlay paths. The solution is well suited to medium-scale overlay networks in the Internet. In other environments, it can be combined with extant probing algorithms to further improve performance.
{"title":"On the cost-quality tradeoff in topology-aware overlay path probing","authors":"Chiping Tang, P. McKinley","doi":"10.1109/ICNP.2003.1249777","DOIUrl":"https://doi.org/10.1109/ICNP.2003.1249777","url":null,"abstract":"Path probing is essential to maintaining an efficient overlay network topology. However, the cost of a full-scale probing is as high as O(n/sup 2/), which is prohibitive in large-scale overlay networks. Several methods have been proposed to reduce probing overhead, although at a cost in terms of probing completeness. In this paper, an orthogonal solution is proposed that trades probing overhead for estimation accuracy in sparse networks such as the Internet. The proposed solution uses network-level path composition information (for example, as provided by a topology server) to infer path quality without full-scale probing. The inference metrics include latency, loss rate and available bandwidth. This approach is used to design several probing algorithms, which are evaluated through analysis and simulation. The results show that the proposed method can significantly reduce probing overhead while providing hounded quality estimations for all n /spl times/ (n - 1) overlay paths. The solution is well suited to medium-scale overlay networks in the Internet. In other environments, it can be combined with extant probing algorithms to further improve performance.","PeriodicalId":179873,"journal":{"name":"11th IEEE International Conference on Network Protocols, 2003. Proceedings.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125840375","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 : 2003-11-04DOI: 10.1109/ICNP.2003.1249753
V. Padmanabhan, Helen J. Wang, P. Chou
We consider the problem of distributing "live" streaming media content to a potentially large and highly dynamic population of hosts. Peer-to-peer content distribution is attractive in this setting because the bandwidth available to serve content scales with demand. A key challenge, however, is making content distribution robust to peer transience. Our approach to providing robustness is to introduce redundance; both in network paths and in data. We use multiple, diverse distribution trees to provide redundancy in network paths and multiple description coding (MDC) to provide redundancy in data. We present a simple tree management algorithm that provides the necessary path diversity and describe an adaptation framework for MDC based on scalable receiver feedback. We evaluate these using MDC applied to real video data coupled with real usage traces from a major news site that experienced a large flash crowd for live streaming content. Our results show very significant benefits in using multiple distribution trees and MDC, with a 22 dB improvement in PSNR in some cases.
{"title":"Resilient peer-to-peer streaming","authors":"V. Padmanabhan, Helen J. Wang, P. Chou","doi":"10.1109/ICNP.2003.1249753","DOIUrl":"https://doi.org/10.1109/ICNP.2003.1249753","url":null,"abstract":"We consider the problem of distributing \"live\" streaming media content to a potentially large and highly dynamic population of hosts. Peer-to-peer content distribution is attractive in this setting because the bandwidth available to serve content scales with demand. A key challenge, however, is making content distribution robust to peer transience. Our approach to providing robustness is to introduce redundance; both in network paths and in data. We use multiple, diverse distribution trees to provide redundancy in network paths and multiple description coding (MDC) to provide redundancy in data. We present a simple tree management algorithm that provides the necessary path diversity and describe an adaptation framework for MDC based on scalable receiver feedback. We evaluate these using MDC applied to real video data coupled with real usage traces from a major news site that experienced a large flash crowd for live streaming content. Our results show very significant benefits in using multiple distribution trees and MDC, with a 22 dB improvement in PSNR in some cases.","PeriodicalId":179873,"journal":{"name":"11th IEEE International Conference on Network Protocols, 2003. Proceedings.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126435695","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 : 2003-11-04DOI: 10.1109/ICNP.2003.1249755
K. M. Hanna, B. Levine, R. Manmatha
We propose and evaluate a mobile, peer-to-peer information retrieval system. Such a system can, for example, support medical care in a disaster by allowing access to a large collections of medical literature. In our system, documents in a collection are replicated in an overlapping manner at mobile peers. This provides resilience in the face of node failures, malicious attacks, and network partitions. We show that our design manages the randomness of node mobility. Although nodes contact only direct neighbors (who change frequently) and do not use any ad hoc routing, the system maintains good IR performance. This makes our design applicable to mobility situations where routing partitions are common. Our evaluation shows that our scheme provides significant savings in network costs, and increased access to information over ad-hoc routing-based approaches; nodes in our system require only a modest amount of additional storage on average.
{"title":"Mobile distributed information retrieval for highly-partitioned networks","authors":"K. M. Hanna, B. Levine, R. Manmatha","doi":"10.1109/ICNP.2003.1249755","DOIUrl":"https://doi.org/10.1109/ICNP.2003.1249755","url":null,"abstract":"We propose and evaluate a mobile, peer-to-peer information retrieval system. Such a system can, for example, support medical care in a disaster by allowing access to a large collections of medical literature. In our system, documents in a collection are replicated in an overlapping manner at mobile peers. This provides resilience in the face of node failures, malicious attacks, and network partitions. We show that our design manages the randomness of node mobility. Although nodes contact only direct neighbors (who change frequently) and do not use any ad hoc routing, the system maintains good IR performance. This makes our design applicable to mobility situations where routing partitions are common. Our evaluation shows that our scheme provides significant savings in network costs, and increased access to information over ad-hoc routing-based approaches; nodes in our system require only a modest amount of additional storage on average.","PeriodicalId":179873,"journal":{"name":"11th IEEE International Conference on Network Protocols, 2003. Proceedings.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133169399","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 : 2003-11-04DOI: 10.1109/ICNP.2003.1249754
L. Zou, M. Ammar
Peer-to-peer systems have quickly become a popular way for file sharing and distribution. In this paper, we focus on the subsystem consisting of peers and their actions relative to a specific file and develop a simple theoretical file-centric model for the subsystem. We begin with a detailed model that tracks the complete system state. To deal with the large system state space, we investigate a decomposed model, which not only greatly reduces the complexity of solving the system, hut also provides a flexible framework for modeling multiple classes of peers and new system features. Using the model, we can study performance measures of a system, such as throughput, success probability of a file search, and number of file replicas in the system. Our model can also be used to understand the impact of user behavior and new system features. As examples, we investigate the effect of freeloaders, holding-enabled downloading and decoys in the paper.
{"title":"A file-centric model for peer-to-peer file sharing systems","authors":"L. Zou, M. Ammar","doi":"10.1109/ICNP.2003.1249754","DOIUrl":"https://doi.org/10.1109/ICNP.2003.1249754","url":null,"abstract":"Peer-to-peer systems have quickly become a popular way for file sharing and distribution. In this paper, we focus on the subsystem consisting of peers and their actions relative to a specific file and develop a simple theoretical file-centric model for the subsystem. We begin with a detailed model that tracks the complete system state. To deal with the large system state space, we investigate a decomposed model, which not only greatly reduces the complexity of solving the system, hut also provides a flexible framework for modeling multiple classes of peers and new system features. Using the model, we can study performance measures of a system, such as throughput, success probability of a file search, and number of file replicas in the system. Our model can also be used to understand the impact of user behavior and new system features. As examples, we investigate the effect of freeloaders, holding-enabled downloading and decoys in the paper.","PeriodicalId":179873,"journal":{"name":"11th IEEE International Conference on Network Protocols, 2003. Proceedings.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122574883","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 : 2003-11-04DOI: 10.1109/ICNP.2003.1249772
Omer Gurewitz, I. Cidon, M. Sidi
Time synchronization is critical in distributed environments. A variety of network protocols, middleware and business applications rely on proper time synchronization across the computational infrastructure and depend on the clock accuracy. The ''network time protocol" (NTP) is the current widely accepted standard for synchronizing clocks over the Internet. NTP uses a hierarchical scheme in order to synchronize the clocks in the network. In this paper we present a novel non-hierarchical peer-to-peer approach for tune synchronization termed CTP - classless time protocol. This approach exploits convex optimization theory in order to evaluate the impact of each clock offset on the overall objective function. We define the clock offset problem as an optimization problem and derive its optimal solution. Based on the solution we develop a distributed protocol that can be implemented over a communication network and prove its convergence to the optimal clock offsets. For compatibility, the CTP may use the exact format and number of messages used by NTP. We also present methodology and numerical results for evaluating and comparing the accuracy of time synchronization schemes. We show that the CTP substantially outperforms hierarchical schemes such as NTP in the sense of clock accuracy with respect to a universal clock, without increasing complexity.
{"title":"Network time synchronization using clock offset optimization","authors":"Omer Gurewitz, I. Cidon, M. Sidi","doi":"10.1109/ICNP.2003.1249772","DOIUrl":"https://doi.org/10.1109/ICNP.2003.1249772","url":null,"abstract":"Time synchronization is critical in distributed environments. A variety of network protocols, middleware and business applications rely on proper time synchronization across the computational infrastructure and depend on the clock accuracy. The ''network time protocol\" (NTP) is the current widely accepted standard for synchronizing clocks over the Internet. NTP uses a hierarchical scheme in order to synchronize the clocks in the network. In this paper we present a novel non-hierarchical peer-to-peer approach for tune synchronization termed CTP - classless time protocol. This approach exploits convex optimization theory in order to evaluate the impact of each clock offset on the overall objective function. We define the clock offset problem as an optimization problem and derive its optimal solution. Based on the solution we develop a distributed protocol that can be implemented over a communication network and prove its convergence to the optimal clock offsets. For compatibility, the CTP may use the exact format and number of messages used by NTP. We also present methodology and numerical results for evaluating and comparing the accuracy of time synchronization schemes. We show that the CTP substantially outperforms hierarchical schemes such as NTP in the sense of clock accuracy with respect to a universal clock, without increasing complexity.","PeriodicalId":179873,"journal":{"name":"11th IEEE International Conference on Network Protocols, 2003. Proceedings.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130155525","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 : 2003-11-04DOI: 10.1109/ICNP.2003.1249760
Ming Zhang, B. Karp, S. Floyd, L. Peterson
TCP performs poorly on paths that reorder packets significantly, where it misinterprets out-of-order delivery as packet loss. The sender responds with a fast retransmit though no actual loss has occurred. These repeated false fast retransmits keep the sender's window small, and severely degrade the throughput it attains. Requiring nearly in-order delivery needlessly restricts and complicates Internet routing systems and routers. Such beneficial systems as multi-path routing and parallel packet switches are difficult to deploy in a way that preserves ordering. Toward a more reordering-tolerant Internet architecture, we present enhancements to TCP that improve the protocol's robustness to reordered and delayed packets. We extend the sender to detect and recover from false fast retransmits using DSACK information, and to avoid false fast retransmits proactively, by adaptively varying dupthresh. Our algorithm is the first that adaptively balances increasing dupthresh, to avoid false fast retransmits, and limiting the growth of dupthresh, to avoid unnecessary timeouts. Finally, we demonstrate that TCP's RTO estimator tolerates delayed packets poorly, and present enhancements to it that ensure it is sufficiently conservative, without using timestamps or additional TCP header hits. Our simulations show that these enhancements significantly improve TCP's performance over paths that reorder or delay packets.
{"title":"RR-TCP: a reordering-robust TCP with DSACK","authors":"Ming Zhang, B. Karp, S. Floyd, L. Peterson","doi":"10.1109/ICNP.2003.1249760","DOIUrl":"https://doi.org/10.1109/ICNP.2003.1249760","url":null,"abstract":"TCP performs poorly on paths that reorder packets significantly, where it misinterprets out-of-order delivery as packet loss. The sender responds with a fast retransmit though no actual loss has occurred. These repeated false fast retransmits keep the sender's window small, and severely degrade the throughput it attains. Requiring nearly in-order delivery needlessly restricts and complicates Internet routing systems and routers. Such beneficial systems as multi-path routing and parallel packet switches are difficult to deploy in a way that preserves ordering. Toward a more reordering-tolerant Internet architecture, we present enhancements to TCP that improve the protocol's robustness to reordered and delayed packets. We extend the sender to detect and recover from false fast retransmits using DSACK information, and to avoid false fast retransmits proactively, by adaptively varying dupthresh. Our algorithm is the first that adaptively balances increasing dupthresh, to avoid false fast retransmits, and limiting the growth of dupthresh, to avoid unnecessary timeouts. Finally, we demonstrate that TCP's RTO estimator tolerates delayed packets poorly, and present enhancements to it that ensure it is sufficiently conservative, without using timestamps or additional TCP header hits. Our simulations show that these enhancements significantly improve TCP's performance over paths that reorder or delay packets.","PeriodicalId":179873,"journal":{"name":"11th IEEE International Conference on Network Protocols, 2003. Proceedings.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134004924","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 : 2003-11-04DOI: 10.1109/ICNP.2003.1249759
Aditya Akella, S. Seshan, H. Balakrishnan
Several recent proposals for sharing congestion information across concurrent flows between end-systems overlook an important problem: two or more flows sharing congestion state may in fact not share the same bottleneck. In this paper, we categorize the origins of this false sharing into two distinct cases: (i) networks with QoS enhancements such as differentiated services, where a flow classifier segregates flows into different queues, and (ii) networks with path diversity where different flows to the same destination address are routed differently. We evaluate the impact of false sharing on flow performance and investigate how false sharing can be detected by a sender. We discuss how a sender must respond upon detecting false sharing. Our results show that persistent overload can be avoided with window-based congestion control even for extreme false sharing, but higher bandwidth flows run at a slower rate. We find that delay and reordering statistics can be used to develop robust detectors of false sharing and are superior to those based on loss patterns. We also find that it is markedly easier to detect and react to false sharing than it is to start by isolating flows and merge their congestion state afterward.
{"title":"The impact of false sharing on shared congestion management","authors":"Aditya Akella, S. Seshan, H. Balakrishnan","doi":"10.1109/ICNP.2003.1249759","DOIUrl":"https://doi.org/10.1109/ICNP.2003.1249759","url":null,"abstract":"Several recent proposals for sharing congestion information across concurrent flows between end-systems overlook an important problem: two or more flows sharing congestion state may in fact not share the same bottleneck. In this paper, we categorize the origins of this false sharing into two distinct cases: (i) networks with QoS enhancements such as differentiated services, where a flow classifier segregates flows into different queues, and (ii) networks with path diversity where different flows to the same destination address are routed differently. We evaluate the impact of false sharing on flow performance and investigate how false sharing can be detected by a sender. We discuss how a sender must respond upon detecting false sharing. Our results show that persistent overload can be avoided with window-based congestion control even for extreme false sharing, but higher bandwidth flows run at a slower rate. We find that delay and reordering statistics can be used to develop robust detectors of false sharing and are superior to those based on loss patterns. We also find that it is markedly easier to detect and react to false sharing than it is to start by isolating flows and merge their congestion state afterward.","PeriodicalId":179873,"journal":{"name":"11th IEEE International Conference on Network Protocols, 2003. Proceedings.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130466577","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 : 2003-11-04DOI: 10.1109/ICNP.2003.1249770
Di-Fa Chang, R. Govindan, J. Heidemann
BGP has been deployed in Internet for more than a decade. However, the events that cause BGP topological changes are not well understood. Although large traces of routing updates seen in BGP operation are collected by RIPE RlS and University of Oregon RouteViews, previous work examines this data set as individual routing updates. This paper describes methods that group routing updates into events. Since one event (a policy change or peering failure) results in many update messages, we cluster updates both temporally and topologically (based on the path vector information). We propose a new approach to analyzing the update traces, classifying the topological impact of muting events, and approximating the distance to the autonomous system originating the event. Our analysis provides some insight into routing behavior: First, at least 45% path changes are caused by events on transit peerings. Second, a significant number (23-37%) of path changes are transient, in that routing updates indicate temporary path changes, but they ultimately converge on a path that is identical from the previously stable path. These observations suggest that a content provider cannot guarantee end-to-end routing stability based solely on its relationship with its immediate ISP, and that better detection of transient changes may improve routing stability.
BGP已经在互联网上部署了十多年。但是，引起BGP拓扑变化的事件还不是很清楚。尽管RIPE RlS和University of Oregon RouteViews收集了BGP操作中看到的大量路由更新痕迹，但之前的工作将这些数据集作为单独的路由更新进行检查。本文描述了将路由更新分组到事件中的方法。由于一个事件(策略更改或对等失败)会导致许多更新消息，因此我们在时间上和拓扑上(基于路径向量信息)对更新进行聚类。我们提出了一种新的方法来分析更新轨迹，对静音事件的拓扑影响进行分类，并逼近到发起事件的自治系统的距离。我们的分析提供了一些关于路由行为的见解:首先，至少45%的路径变化是由过境节点上的事件引起的。其次，大量(23-37%)的路径变化是短暂的，因为路由更新表明临时路径变化，但它们最终收敛到与先前稳定路径相同的路径上。这些观察结果表明，内容提供者不能仅仅基于与其直接ISP的关系来保证端到端路由的稳定性，更好地检测瞬态变化可能会提高路由的稳定性。
{"title":"The temporal and topological characteristics of BGP path changes","authors":"Di-Fa Chang, R. Govindan, J. Heidemann","doi":"10.1109/ICNP.2003.1249770","DOIUrl":"https://doi.org/10.1109/ICNP.2003.1249770","url":null,"abstract":"BGP has been deployed in Internet for more than a decade. However, the events that cause BGP topological changes are not well understood. Although large traces of routing updates seen in BGP operation are collected by RIPE RlS and University of Oregon RouteViews, previous work examines this data set as individual routing updates. This paper describes methods that group routing updates into events. Since one event (a policy change or peering failure) results in many update messages, we cluster updates both temporally and topologically (based on the path vector information). We propose a new approach to analyzing the update traces, classifying the topological impact of muting events, and approximating the distance to the autonomous system originating the event. Our analysis provides some insight into routing behavior: First, at least 45% path changes are caused by events on transit peerings. Second, a significant number (23-37%) of path changes are transient, in that routing updates indicate temporary path changes, but they ultimately converge on a path that is identical from the previously stable path. These observations suggest that a content provider cannot guarantee end-to-end routing stability based solely on its relationship with its immediate ISP, and that better detection of transient changes may improve routing stability.","PeriodicalId":179873,"journal":{"name":"11th IEEE International Conference on Network Protocols, 2003. Proceedings.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131175348","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 : 2003-11-04DOI: 10.1109/ICNP.2003.1249757
S. Fahmy, Minseok Kwon
Overlay networks among cooperating hosts have recently emerged as a viable solution to several challenging problems, including multicasting, routing, content distribution, and peer-to-peer services. Application-level overlays, however, incur a performance penalty over router level solutions. This paper characterizes this performance penalty for overlay multicast trees via experimental data, simulations, and theoretical models. Experimental data and simulations illustrate that (i) the average delay and the number of hops between parent and child hosts in overlay trees generally decrease, and (ii) the degree of hosts generally decreases, as the level of the host in the overlay tree increases. Overlay multicast routing strategies, together with power-law and small-world Internet topology characteristics, are causes of the observed phenomena. We compare three overlay multicast protocols with respect to latency, bandwidth, router degrees, and host degrees. We also quantify the overlay tree cost. Results reveal that L(n)/U(n) /spl prop/ n/sub 0.9/ for small n, where L(n) is the total number of hops in all overlay links, U(n) is the average number of hops on the source to receiver unicast paths, and n is the number of members in the overlay multicast session.
{"title":"Characterizing overlay multicast networks","authors":"S. Fahmy, Minseok Kwon","doi":"10.1109/ICNP.2003.1249757","DOIUrl":"https://doi.org/10.1109/ICNP.2003.1249757","url":null,"abstract":"Overlay networks among cooperating hosts have recently emerged as a viable solution to several challenging problems, including multicasting, routing, content distribution, and peer-to-peer services. Application-level overlays, however, incur a performance penalty over router level solutions. This paper characterizes this performance penalty for overlay multicast trees via experimental data, simulations, and theoretical models. Experimental data and simulations illustrate that (i) the average delay and the number of hops between parent and child hosts in overlay trees generally decrease, and (ii) the degree of hosts generally decreases, as the level of the host in the overlay tree increases. Overlay multicast routing strategies, together with power-law and small-world Internet topology characteristics, are causes of the observed phenomena. We compare three overlay multicast protocols with respect to latency, bandwidth, router degrees, and host degrees. We also quantify the overlay tree cost. Results reveal that L(n)/U(n) /spl prop/ n/sub 0.9/ for small n, where L(n) is the total number of hops in all overlay links, U(n) is the average number of hops on the source to receiver unicast paths, and n is the number of members in the overlay multicast session.","PeriodicalId":179873,"journal":{"name":"11th IEEE International Conference on Network Protocols, 2003. Proceedings.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132558706","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}
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