ShortCuts: Using Soft State to Improve DHT Routing

Abstract

Distributed hash tables are increasingly being proposed as the core substrate for content delivery applications in the Internet, such as cooperative Web caches, Web index and search, and content delivery systems. The performance of these applications built on DHTs fundamentally depends on the effectiveness of request routing within the DHT. In this paper, we show how to use soft state to achieve routing performance that approaches the aggressive performance of one-hop schemes, but with an order of magnitude less overhead on average. We use three kinds of hint caches to improve routing latency: local hint caches, path hint caches, and global hint caches. Local hint caches use large successor lists to short cut final hops. Path hint caches store a moderate number of effective route entries gathered while performing lookups for other nodes. And global hint caches store direct routes to peers distributed across the ID space. Based upon our simulation results, we find that the combination of the hint caches significantly improves Chord routing performance: in a network of 4,096 peers, the hint caches enable Chord to route requests with average latencies only 6% more than algorithms that use complete routing tables with significantly less overhead.

Shortcut Creation for MeNW in the Consideration of Topological Structure and Message Exchanged

“…In this case, for example, if q = p + A and r = p + 2B + 1 (A > B), then x = A − B satisfies Eq. (20). Consequently, the proposition is proved.…”

“…In [20], the authors proposed three different types of a shortcut: local hint cache, path hint cache, and global hint cache. The local hint cache can be considered as an enlarged successor list, which includes connections to its immediate neighbors.…”

“…Therefore, plural x does not satisfy Eq. (20). Finally, consider the case where s t is constant (ex.…”

“…In this section, we evaluate the efficiency of the network resources in the whole MeNW that the shortcut based on the optimal EC value brings. First, we prepare two kind of the network; one including the shortcut created by Path Hint Cache (HC) [20], the other including the shortcut created by the optimum EC value (EC), respectively. After that, we measure the length of the path through which all messages pass in these networks, and compare the approaches of EC with HC.…”

A locality aware cache diffusion system

“…[27] uses cached routing information to accelerate DHT lookups. This extra routing information is used to improve performance so that routing in a DHT is as close to direct routing as possible.…”