1. WebTP: Protocol Design Issues Jeng Lung & Yogesh Bhumralkar

2. Introduction Following key issues related to the design and testing of the protocol: –Congestion Window Control –Retransmission Timeout Scheme –Performance under Network Jitter

3. Congestion Control Background –WebTP uses TCP-style congestion control –2 Phases: Slow Start Congestion Avoidance: Additive Increase/Multiplicative Decrease –TCP biased against long connections; therefore, WebTP faces same dilemma.

4. Improving Fairness Maximize fairness by modifying Additive Increase Instead of increasing cwnd by 1/cwnd, increase it by K=c*rtt*rtt. This makes it more fair Problem: Find optimal K for fairness K is topology dependent but still want to ensure that the scheme works for WebTP.

5. Network Topology

7. Retransmission Scheme Current timeout set to: M is the receiver’s tolerance to jitter. Examine the effects of changing M on the number of dropped and duplicate packets.

9. Jitter Study Any network has considerable random delays. The time between when the packet is transmitted to when it reaches the receiver varies a great deal - this phenomenon is called jitter. Simulated jitter by introducing random delay to each packet on the sender side.

12. Conclusion Congestion Window Scheme: Optimal K depends on network topology. Retransmission Scheme: Dropped packets increase with M whereas the number of duplicate packets goes down at higher M. Network Jitter: Higher jitter implies that a higher M is required to handle the delays that are introduced.