We propose a simple distributed hash table called ReCord, which is a generalized version of Randomized-Chord and offers improved tradeoffs in performance and topology maintenance over existing P2P systems. ReCord is scalable and can be easily implemented as an overlay network, and offers a good tradeoff between the node degree and query latency. For instance, an @math -node ReCord with @math node degree has an expected latency of @math hops. Alternatively, it can also offer @math hops latency at a higher cost of @math node degree. Meanwhile, simulations of the dynamic behaviors of ReCord are studied.
It is difficult to say which one of above proposed DHTs is best". Each routing algorithm offers some insight on routing in overlay network. One appropriate strategy is to combine these insights and formulate an even better scheme @cite_0 .
@cite_0
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Dipsea is a modular architecture for building a Distributed Hash Table (DHT). A DHT is a large hash table that is cooperatively maintained by a large number of machines communicating over the Internet. Decentralization and automatic re-configuration are two key design goals for a DHT. The architecture of Dipsea consists of three layers: ID Management, Overlay Routing and Data Management. The Overlay Routing layer consists of three modules: Emulation Engine, Ring Management and Choice of Long-Distance Links. Efficient algorithms for ID Management are designed—these algorithms require few messages, require few re-assignments of existing IDs and ensure that the hash table is divided among the participating machines as evenly as possible. Ring Management ensures that participating machines establish connections among themselves, as a function of their IDs, to form a fault-tolerant ring. The Emulation Engine is responsible for “emulation” of arbitrary families of routing networks. It handles issues arising out of dynamism (arrival and departure of participating machines), scale (variation in the average number of participating machines) and physical network proximity. Choice of Long-Distance Links allows a DHT to choose any family of routing networks (deterministic or randomized) for emulation. Several deterministic and randomized routing networks are designed and analyzed. Among these are Symphony (one of the first randomized DHT routing networks), Papillon (a deterministic routing network that guarantees asymptotically optimal route lengths with greedy routing for a fixed out-degree of nodes), and Mariposa (a randomized routing network that also guarantees optimal route lengths for a given out-degree of nodes). This paper presents Virtual Ring Routing (VRR), a new network routing protocol that occupies a unique point in the design space. VRR is inspired by overlay routing algorithms in Distributed Hash Tables (DHTs) but it does not rely on an underlying network routing protocol. It is implemented directly on top of the link layer. VRR provides both raditional point-to-point network routing and DHT routing to the node responsible for a hash table key.VRR can be used with any link layer technology but this paper describes a design and several implementations of VRR that are tuned for wireless networks. We evaluate the performance of VRR using simulations and measurements from a sensor network and an 802.11a testbed. The experimental results show that VRR provides robust performance across a wide range of environments and workloads. It performs comparably to, or better than, the best wireless routing protocol in each experiment. VRR performs well because of its unique features: it does not require network flooding or trans-lation between fixed identifiers and location-dependent addresses. The equality and anonymity of peer-to-peer networks makes them vulnerable to routing denial of service attacks from misbehaving nodes. In this paper, we investigate how existing social networks can benefit P2P networks by leveraging the inherent trust associated with social links. We present a trust model that lets us compare routing algorithms for P2P networks overlaying social networks. We propose SPROUT, a DHT routing algorithm that significantly increases the probability of successful routing by using social links. Finally, we discuss further optimization and design choices for both the model and the routing algorithm. In the past few years, more and more researchers have paid close attention to the emerging field of delay tolerant networks (DTNs), in which network often partitions and end-to-end paths do not exist nearly all the time. To cope with these challenges, most routing protocols employ the "store-carry-forward" strategy to transmit messages. However, the difficulty of this strategy is how to choose the best relay node and determine the best time to forward messages. Fortunately, social relations among nodes can be used to address these problems. In this paper, we present a comprehensive survey of recent social-aware routing protocols, which offer an insight into how to utilize social relationships to design efficient and applicable routing algorithms in DTNs. First, we review the major practical applications of DTNs. Then, we focus on understanding social ties between nodes and investigating some design-related issues of social-based routing approaches, e.g., the ways to obtain social relations among nodes, the metrics and approaches to identify the characteristics of social ties, the strategies to optimize social-aware routing protocols, and the suitable mobility traces to evaluate these protocols. We also create a taxonomy for social-aware routing protocols according to the sources of social relations. Finally, we outline several open issues and research challenges.