A Promotion Mechanism for Scalable Stealth DHT

Most Distributed Hash Tables (DHTs) inherently assume interconnecting nodes with homogeneous capabilities. Realistically however, capabilities of nodes on a network widely vary, leading traditional DHTs to inevitably exhibit poor performance in real-world environments. Stealth DHT was previously proposed to address node heterogeneity by enabling a DHT to separate highly capable (super-peers or service) nodes from less capable (stealth) nodes. Stealth DHTs are considered robust and flexible due to the way they organize nodes on the network. However, it is difficult to over-provision the number of service nodes to support unexpected increase in user requests in the networks. Unlike traditional DHTs therefore, Stealth DHTs cannot guarantee network scalability. In this paper, we address this problem by proposing a simple promotion mechanism to extend Stealth DHT to use stealth nodes as back-up resources that it can use when the network is overloaded. We define promotion of stealth nodes as the act of enabling stealth nodes execute some or all of the operations of service nodes. Experiments results show that the proposed promotion mechanism can offload significant proportion of network load.