1. TCP on High-Speed Networks Sangtae Ha and Injong Rhee North Carolina State University

2. TCP is bad for large BDP path TCP has been known for under-utilization for large BDP path because of its slow window increase (1/CWND for each ACK) Two TCP-SACK flows with background traffic in the testbed (400Mbps, 160ms RTT). RTT Utilization(%)

3. Internet2 testing over 1Gbps Packet loss Time (RTT)Congestion avoidance Packet loss cwnd Slow start Packet loss Internet2 path between NICT in Japan and UIC in Chicago 1Gbps and 200ms RTT One ideal TCP flow testing, followed by 1 TCP-SACK flow testing 22,00010Gbps 8000 46 minutes 37 minutes TCP big decrease slow increase

4. Results Throughput CWD RTT IDEAL TCP-SACK

5. LAB test-bed

6. Slow Start is bad for large BDP path Slow Start probes an available bandwidth very fast (exponentially) BUT, # of packet drops can be well beyond BDP, so it is more problematic for a large BDP path

7. LAB Testbed testing Linux 2.6.23.9 Bandwidth: 400Mbps Two TCP-SACK flows 40ms RTT vs 280ms RTT

8. Results 40ms vs 280ms RTT

9. File completion time demo Compare the file completion time between TCP-SACK flow and I-Protocol flow