CS268 Course Project Understanding Chord Performance and Topology-aware Overlay Construction for Chord
Abstract:
We studied performance of the Chord scalable lookup system with several performance enhancements. For the denser finger technique, we gave analytical result that shows the average lookup path length decreases slower than the maximum length and converges to it as finger density grows higher. Location cache, as implemented in MIT Chord, is shown to be able to reduce the lookup path length by 1/2 of the logarithm of cache size, which makes it very effective in static networks. However, our experiments with the MIT Chord implementation shows that because of the stale-entry problem, the location cache does not scale to more than 2000 nodes in a typical file-swapping network setting and there are plenty of room for improvement. We found that server selection is an effective way of reducing lookup stretch. In the ideal exponential delay network, Chord with server selection and a O(log 2 N) entry routing table will have O(1) lookup stretch. In a transit-stubs network, server selection still achieves 50 % improvement of lookup stretch. The other part of our work is a topologyaware overlay construction scheme for Chord. During the setup of the network, Principle Component Analysis is used to select representative landmarks from a pool of nodes and place the landmarks to appropriate positions on the Chord ID circle. Later a two-level approach is used to assign each new node a locally optimal ID. Preliminary results show that this improves routing locality of the Chord algorithm. 21 % reduction in lookup stretch is observed in a 600-node transit stub topology. 1
Citations
| 2113 | Chord: A scalable peer-to-peer lookup service for internet applications – Stoica, Morris, et al. |
| 1749 | A scalable content-addressable network – Ratnasamy, Francis, et al. - 2001 |
| 1137 | Pastry: Scalable, distributed object location and routing for large-scale peer-to-peer systems – Rowstron, Druschel - 2001 |
| 581 | Wide-area cooperative storage with CFS – Dabek, Kaashoek, et al. - 2001 |
| 186 | Digital Image Processing – Gonzalez, Wintz - 1977 |
| 112 | Exploiting network proximity in peer-to-peer overlay networks – CASTRO, DRUSCHEL, et al. - 2002 |
| 104 | Routing algorithms for DHTs: Some open questions – Ratnasamy, Shenker, et al. - 2002 |
| 58 | Brocade: Landmark rout-ing on overlay networks – ZHAO, DUAN, et al. |
| 16 | Distributed data location in a dynamic network – Hildrum, Kubiatowicz, et al. - 2002 |
| 12 | Structured peer-to-peer overlays need application-driven benchmarks – Rhea, Roscoe, et al. |
