1. TCP/IP Performance across Optical Packet-Switched (OPS) Networks Jingyi He ( Co-supervised by Dr. Gary Chan and Dr. Danny Tsang ) Apr. 25, 2002

2. Outline The perspective of OPS networks Special features of OPS networks (our research motivations) Deflection routing Packet aggregation Simulation model and results Conclusions

3. Towards the Optical Internet … Current Internet Point-to-Point WDM links Electronic routers (switches) O/E/O conversion Electronic bottleneck Near-term Solution: Wavelength-Routed Networks

4. Electronic routers  Wavelength- routing switches Lightpaths Problem: circuit switching low bandwidth efficiency Wavelength-Routed Networks

5. Optical Burst-Switched Networks A compromise between circuit-switching and packet-switching A control packet is first sent to set up the “ connection ” for a burst, which is released as soon as the burst is sent Bandwidth is reserved for a shorter time than circuit-switching  higher bandwidth efficiency

6. The Eventual Solution … may be OPS Networks! Large capacity High bandwidth efficiency Rich routing functionalities Great flexibility and reliability

7. An Example

8. Special Features Deflection Routing A contention resolution scheme in case of no optical buffer Packet Aggregation To relieve the optical packet switches of the heavy burden of processing each individual (small) packet Possible schemes: mixed-flow, per-flow

9. Motivations of Our Research Deflection routing  Out-of-order delivery of packets Packet aggregation  In case of deflection or packet dropping, the effect may be magnified What ’ s their impact on TCP/IP performance?

10. Simulation Simulator: ns-2 Simulation model:

11. Performance Metrics TCP throughput (goodput) TCP fairness among the flows Jain ’ s Fairness Index: f  (0, 1], with f =1 meaning perfect fairness

12. Mixed-flow Aggregation

13. Per-flow Aggregation

14. Comparison

15. Conclusions Deflection routing significantly improves the TCP fairness Mixed-flow aggregation outperforms per-flow aggregation in terms of both TCP throughput and fairness Q & A