August 10, Circuit TCP (CTCP) Helali Bhuiyan

August 10, 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

August 10, Linux v Sender Socket API TCP IP DLL NIC II web100 lib /proc web100 Instr. CTCP-web100 -patch CTCP patch NIC I Linux v 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

August 10, Linux v Sender Socket API TCP IP DLL NIC II web100 lib /proc web100 Instr. CTCP-web100 -patch CTCP patch NIC I Linux v 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

August 10, Linux v Sender Socket API TCP IP DLL NIC II web100 lib /proc web100 Instr. CTCP-web100 -patch CTCP patch NIC I Linux v 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

August 10, Linux v Sender Socket API TCP IP DLL NIC II web100 lib /proc web100 Instr. CTCP-web100 -patch CTCP patch NIC I Linux v 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

August 10, 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 Cheetah- nc Wuneng H Raleigh PoP OC GbE G bE 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 G H UVa mvstu6

August 10, 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) TCP CTCP Throughput (Mbps) over 1 Gb/s circuit, RTT = 8.7ms

August 10, Thank You

August 10, 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

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

August 10, CTCP Performance