Hash tables – which map “keys ” onto “values” – are an essential building block in modern software systems. We believe a similar functionality would be equally valuable to large distributed systems. In this paper, we introduce the concept of a Content-Addressable Network (CAN) as a distributed infrastructure that provides hash table-like functionality on Internet-like scales. The CAN is scalable, fault-tolerant and completely self-organizing, and we demonstrate its scalability, robustness and low-latency properties through simulation.

Testing of network protocols and distributed applications has become increasingly complex, as the diversity of networks and underlying technologies increase, and the adaptive behavior of applications becomes more sophisticated. In this paper, we present NIST Net, a tool to facilitate testing and experimentation with network code through emulation. NIST Net enables experimenters to model and effect arbitrary performance dynamics (packet delay, jitter, bandwidth limitations, congestion, packet loss and duplication) on live IP packets passing through a commodity Linux-based PC router. We describe the emulation capabilities of NIST Net; examine its architecture; and discuss some of the implementation challenges encountered in building such a tool to operate at very high network data rates while imposing minimal processing overhead. Calibration results are provided to quantify the fidelity and performance of NIST Net over a wide range of offered loads (up to 1 Gbps), and a diverse set of emulated performance dynamics. 1

The ability to estimate network latencies between arbitrary Internet end hosts would enable new measurement studies and applications, such as investigating routing path inefficiencies on a wide-scale or constructing topologically sensitive overlay networks. In this paper we present King, a tool that accurately and quickly estimates the latency between arbitrary end hosts by using recursive DNS queries in a novel way. Compared to previous approaches, King has several advantages. Unlike IDMaps, King does not require the deployment of additional infrastructure, and unlike GNP, King does not require end hosts to agree upon a set of reference points. Unlike both IDMaps and GNP, King's estimates are based on direct online measurements rather than offline extrapolation. Because King uses existing DNS infrastructure, King scales naturally both in terms of the number of hosts that can be measured and in terms of the number of hosts performing measurements.

Advanced architectures for performance analysis of QoS enabled applications and services need to integrate different components which are not only concerned with the end-to-end QoS measurement and monitoring, but also with network path performance analysis and QoS modeling. Additionally, the performance analysis for QoS enabled applications and services requires the integration of further components for topology and autonomous system discovery as well as QoS/SLA verification dependent on the Internet environment (intra- and inter- domain). To illustrate novel concepts for integrated performance analysis in an intra- and inter-domain environment, the Distributed Measurement Architecture (DMA) together with its component- CMToolset- developed in the framework of the European IST project AQUILA [1] is presented. CMToolset is used in AQUILA for end-to-end QoS measurement and verification considering traffic aggregation, multiplexing and resource reservation in DiffServ/MPLS environment. Usage scenarios for QoS analysis based on practical experiences with CMToolset are addressed. The novel concepts of Inter-domain Distributed Measurement Architecture (IDMA) based on the enhancements of AQUILA DMA in the framework of INTERMON project [21] are discussed. AQUILA DMA is compared with current state of the art of integrated toolkits for performance analysis of QoS enabled application and services. 1.

Abstract. We initiate a study on the effect of the network topology on the performance of Peer-to-Peer (P2P) information retrieval systems. The emerging P2P model has become a very powerful and attractive paradigm for developing Internet-scale systems for sharing resources, including files, or documents. We show that the performance of Information Retrieval algorithms can be significantly improved through the use of fully distributed topologically aware overlay network construction techniques. Our empirical results, using the Peerware middleware infrastructure, show that the approach we propose is both efficient and practical. 1

Abstract — We present a distributed rendezvous mechanism to solve the network neighborhood discovery problem in large-scale distributed systems. Our scheme uses the existing distributed peer-to-peer lookup mechanisms such as Chord to provide network neighborhood discovery. Our idea is for each host to compute a location key that characterizes its network location on the Internet. A node then uses this location key to perform a Chord lookup on its nearby peer node. We focus on the issue of how to generate the location key in a distributed fashion such that nodes that are close to each other in the actual network will have similar location key values, and will therefore be mapped to nearby locations on the Chord ring. Using real network measurements from NLANR and large-scale topologies generated by GT-ITM, we compare the performance of our scheme with a random mapping scheme. Simulation results show that significant performance gains can be achieved by probing only a small number of nodes using our scheme. I.