Relay discovery and selection for large-scale P2P streaming.
Relay discovery and selection for large-scale P2P streaming.
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DOI：
10.1371/journal.pone.0175360
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发表时间：
2017
期刊：
影响因子：
3.7
通讯作者：
Hei X
中科院分区：
文献类型：
--
作者：
Zhang C;Wang AY;Hei X
在对等网络中，应用中继器通常用于提供各种联网服务。如果根据中继站的网络位置适当地选择中继站，则服务性能通常显著提高。本文研究了大规模P2P流媒体网络中位置感知的中继发现和选择问题。在这些大规模的、动态的覆盖网络中，为了找到足够大的中继候选集，进而选择一个性能较好的中继，需要花费大量的通信和计算代价。网络位置可以直接或间接测量，权衡时效性、开销和准确性。基于测量研究和相关的误差分析，我们证明了间接测量，如King和互联网坐标系(ICS)，只能实现对节点网络位置的粗略估计，而那些基于纯间接测量的方法不能产生良好的中继选择。我们还使用三个公开可用的RTT数据集，证明了常用的“K中最佳”选择方法存在显著的误差放大。我们提出了一种两阶段的方法来实现高效的中继发现和准确的中继选择。间接测量被用来缩小少数高质量的中继候选范围，并基于直接探测来细化最终的中继选择。这种两阶段方法使用分布式哈希表(DHT)进行了有效的实施。当构建分布式哈希表时，节点关键字携带位置信息，并且它们是使用间接测量(例如ICS坐标)可扩展地生成的。利用基于分布式哈希表的搜索有效地实现了中继发现。我们评估了这种基于分布式哈希表的方法的各个方面，包括分布式哈希表的索引过程、节点流失情况下的密钥生成和消息开销。
In peer-to-peer networks, application relays have been commonly used to provide various networking services. The service performance often improves significantly if a relay is selected appropriately based on its network location. In this paper, we studied the location-aware relay discovery and selection problem for large-scale P2P streaming networks. In these large-scale and dynamic overlays, it incurs significant communication and computation cost to discover a sufficiently large relay candidate set and further to select one relay with good performance. The network location can be measured directly or indirectly with the tradeoffs between timeliness, overhead and accuracy. Based on a measurement study and the associated error analysis, we demonstrate that indirect measurements, such as King and Internet Coordinate Systems (ICS), can only achieve a coarse estimation of peers’ network location and those methods based on pure indirect measurements cannot lead to a good relay selection. We also demonstrate that there exists significant error amplification of the commonly used “best-out-of-K” selection methodology using three RTT data sets publicly available. We propose a two-phase approach to achieve efficient relay discovery and accurate relay selection. Indirect measurements are used to narrow down a small number of high-quality relay candidates and the final relay selection is refined based on direct probing. This two-phase approach enjoys an efficient implementation using the Distributed-Hash-Table (DHT). When the DHT is constructed, the node keys carry the location information and they are generated scalably using indirect measurements, such as the ICS coordinates. The relay discovery is achieved efficiently utilizing the DHT-based search. We evaluated various aspects of this DHT-based approach, including the DHT indexing procedure, key generation under peer churn and message costs.