1. Grid Computing slide to be used anywhere Harness global resources to improve performance

2. Available Bandwidth Available bandwidth = unused bandwidth on path Key metric for data intensive applications

3. Grid Application: Predict Download Time Dynamically schedule tasks based on bandwidth availability

4. Optimal Path Selection Choose path to minimize download time from A to D

5. Chirp Probing Chirp: exponential flight pattern of probes Non-intrusive and Efficient: wide range of probing bit rates, few packets

6. pathChirp Tool Based on the principle of self-induced congestion

7. Internet Experiments 3 common hops between SLAC  Rice and Chicago  Rice paths Estimates fall in proportion to introduced Poisson traffic

8. CAIDA Gigabit Testbed Experiments Smartbit cross-traffic generator Estimates track changes in available bandwidth Performance improves with increasing packet size

9. Comparison with Pathload Rice ECE network 100Mbps links pathChirp uses 10 times fewer bytes for comparable accuracy Available bandwidth EfficiencyAccuracy pathchirppathloadpathChirp 10-90% pathload Avg.min-max 30Mbps0.35MB3.9MB19-29Mbps16-31Mbps 50Mbps0.75MB5.6MB39-48Mbps39-52Mbps 70Mbps0.6MB8.6MB54-63Mbps63-74Mbps

10. Conclusions pathChirp: non-intrusive available bandwidth probing tool Successful tests on the Internet and Gigabit testbed Upto 10x improvement over state-of-the-art pathload on Rice ECE network URL: spin.rice.edu