1. August 10, 20061 Circuit TCP (CTCP) Helali Bhuiyan helali@virginia.edu

2. August 10, 20062 CTCP: concept and value  Once a dedicated circuit is setup between two end hosts, TCP seems to be a fine transport solution for large files window-based flow control handles variations in receive rate no packet loss → no reduction in sending rate  circuit switches on path with reserved bandwidth  window size reports in ACKs prevent receive buffer losses assume send and receive buffer size = BDP  But for small files initial Slow Start in TCP on send side and Linux autotuning enhancement to slowly increase receive buffer hurts throughput hence CTCP

3. August 10, 20063 Linux v2.6.11 Sender Socket API TCP IP DLL NIC II web100 lib /proc web100 Instr. CTCP-web100 -patch CTCP patch NIC I Linux v2.6.11 Receiver web100 lib Socket API TCP IP DLL NIC INIC II Interne t cheetah /proc web100 Instr. CTCP Software Implementation Setup a circuit CTCP patch CTCP-web100 -patch

4. August 10, 20064 Linux v2.6.11 Sender Socket API TCP IP DLL NIC II web100 lib /proc web100 Instr. CTCP-web100 -patch CTCP patch NIC I Linux v2.6.11 Receiver web100 lib Socket API TCP IP DLL NIC INIC II Interne t cheetah /proc web100 Instr. CTCP Software Implementation C-iperf Run user application CTCP API CTCP patch CTCP-web100 -patch

5. August 10, 20065 Linux v2.6.11 Sender Socket API TCP IP DLL NIC II web100 lib /proc web100 Instr. CTCP-web100 -patch CTCP patch NIC I Linux v2.6.11 Receiver web100 lib Socket API TCP IP DLL NIC INIC II Interne t cheetah /proc web100 Instr. CTCP Software Implementation C-iperf User application creates a TCP socket CTCP API CTCP patch CTCP-web100 -patch

6. August 10, 20066 Linux v2.6.11 Sender Socket API TCP IP DLL NIC II web100 lib /proc web100 Instr. CTCP-web100 -patch CTCP patch NIC I Linux v2.6.11 Receiver web100 lib Socket API TCP IP DLL NIC INIC II Interne t cheetah /proc web100 Instr. CTCP Software Implementation C-iperf CTCP API Activate CTCP -disable congestion control - set buffer sizes to BDP value - disable autotuning CTCP patch CTCP-web100 -patch

7. August 10, 20067 Demonstration  Setup a circuit between zelda3 to mvstu6  C-iperf and iperf server are running on zelda3  Run C-iperf and iperf client on mvstu6  Comparison between C-iperf with iperf 5MB transfer 10MB transfer 1G 1-8-33 1-8-34 1-8-35 1-8-36 1-6-1 1-6-17 1-8-37 1-7-1 1-8-38 1-7-17 Cheetah- nc Wuneng 1-8- 39 H Raleigh PoP OC192 1-6-1 1-6-17 10GbE 1-7-1 G bE 1-7-33 1-7-34 1-7-35 1-7-36 1-7-37 1-7-38 1-7-39 H H H Cheetah- atl Atlanta PoP Zelda 1 Zelda 2 Zelda 3 1G Orbitty Cluster 1G NCSU H H Centuar FastIron FESX448 UVa Catalyst 4948 1G H UVa mvstu6

8. August 10, 20068 Measurements  Throughput gains of CTCP over TCP for small transfer sizes For transfers in bursts, cwnd resets during idle times  Throughput gain decreases as transfer size increases Transfer Size (KB) 100100050001000050000100000500000 TCP 18106336474726783836 CTCP 43307632710827851873 Throughput (Mbps) over 1 Gb/s circuit, RTT = 8.7ms

9. August 10, 20069 Thank You

10. August 10, 200610 Local Testbed  Setup a circuit between mvstu3 to mvstu6  mvstu4 is running as a WAN emulator  C-iperf and iperf server are running on mvstu3  Run C-iperf and iperf client on mvstu6  Comparison between C-iperf with iperf 5MB transfer 10MB transfer

11. August 10, 200611 CTCP Behavior Start-up behavior of TCP and CTCP

12. August 10, 200612 CTCP Performance