Hierarchical DHT-based name resolution for information-centric networks

Information-centric network (ICN) architectures are an increasingly important approach for the future Internet. Several ICN approaches are based on a flat object ID namespace and require some kind of global name resolution service to translate object IDs into network addresses. Building a world-wide NRS for a flat namespace with 10(16) expected IDs is challenging because of requirements such as scalability, low latency, efficient network utilization, and anycast routing that selects the most suitable copies. In this paper, we present a general hierarchical NRS framework for flat ID namespaces. The framework meets those requirements by the following properties: The registration and request forwarding matches the underlying network topology, exploits request locality, supports domain-specific copies of binding entries, can offer constant hop resolution (depending on the chosen underlying forwarding scheme), and provides scoping of publications. Our general NRS framework is flexible and supports different instantiations. These instantiations offer an important trade-off between resolution-domain (i.e. subsystem) autonomy (simplifying deployment) and reduced latency, maintenance overhead, and memory requirements. To evaluate this trade-off and explore the design space, we have designed two specific instantiations of our general NRS framework: MDHT and HSkip. We have performed a theoretical analysis and a simulation-based evaluation of both systems. In addition, we have published an implementation of the MDHT system as open source. Results indicate that an average request latency of (well) below 100 ms is achievable in both systems for a global system with 12 million NRS nodes while meeting our other specific requirements. These results imply that a flat namespace can be adopted on a global scale, opening up several design alternatives for information-centric network architectures. (C) 2013 Elsevier B.V. All rights reserved.