嵌套式Chord路由系统研究

Researching on Embedded Chord Routing System

在P2P网络中,DHT(Distilbute Hash Table,即分布式哈希表)在应用层上把所有的节点组织成一个结构化的重叠网络,文件索引分布其中,查询报文将通过这个重叠网络路由。DHT在节点失效、遭受攻击和突发性高负载面前都能表现出很好的健壮性;但是目前DHT还面临许多问题,其中之一就是DHT在初始设计时忽略了参与节点在物理网络上的邻近性,导致重叠网络和物理网络脱节,即DHT未能充分利用底层物理网络的拓扑信息,从而造成实际的寻路效率低下。因为路由算法是DHT的核心,所以提高DHT寻路效率是当前基于DHT的P2P研究的重点,具有很重要的意义。国际上几个研究小组独立地提出了Chord、CAN、Pastry和Tapestry等基于DHT的结构化P2P系统。本文提出了一种构造嵌套式Chord的方案,既改进了寻路效率又保持了原有DHT系统的负载平衡性质。该方案具有完全分布式的特点。利用这种思想对Chord进行了改进,构造了嵌套式Chord。仿真的结果证明了该方案的有效性。

In P2P networks, DHTs reorganize peers into an overlay in the application level, distribute file indexes into the network, and route queries through the overlay. DHTs are robust in the face of failures, attacks and unexpectedly high loads. However, DHTs are still faced with many problems, one of which is the fact that most DHTs do not take into account physical network topology in their original design, thus resulting in high routing latency and low efficiency. Therefore, to improve routing performance is an im- portant direction for research on DHT-based P2P. several research groups independently proposed DHT （distributed hash table） systems, which include Chord, CAN, Pastry and Tapestry. This paper Devise a novel scheme to construct embedded DHT, which can not only improve the routing efficiency, but also inherit the load-balancing feature of the original DHT. To illustrate the feasibility and effectiveness of the scheme, we construct eChord upon the original Chord system. Analysis and simulation demonstrate that our scheme is very effective.