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This study explores the Datagram Congestion Control Protocol (DCCP) and its performance in managing bursty traffic for real-time applications. The TCP-like congestion control algorithm is examined, along with simulation results and conclusions. Findings highlight bandwidth consumption adjustments, fairness among flows, and more.
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Performance Evaluations of DCCP for Bursty Traffic in Real-time Applications Author: Shigeki Takeuchi,Hiroyuki Koga, Katsuyoshi Iida, Youki Kadobayashi, Suguru Yamaguchi Proceedings of the The 2005 Symposium on Applications and the Internet (SAINT'05) Speaker: Jia-Yu Wang
Outline • Introduction • TCP-like Congestion Control (CCID2) • Simulation Results • Conclusions • Reference
Introduction_1 • Datagram Congestion Control Protocol (RFC 4340)
Introduction_2 • Unreliable • No re-transmissions • Reliable handshakes for connection setup and teardown • Has modular congestion control • Can detect congestion and take avoiding action • Different algorithms can be selected – CCID • TCP-like Congestion Control (CCID2) • TCP Friendly Rate Control (CCID3) • Packet sequence numbers
TCP-like Congestion Control (CCID2)_1 • The CCID2 algorithm is based on the AIMD (Additive Increase Multiplicative Decrease) TCP Congestion control
TCP-like Congestion Control (CCID2)_2 • Differences between CCID 2 and straight TCP congestion control include the following: • CCID 2 applies congestion control to acknowledgements • The congestion window cwnd have units of packets in DCCP • As an unreliable protocol, DCCP never retransmits a packet
Simulation Model • NS2(Network Simulator – v.2.26)
Comparison of DCCP and UDP_2 Summary of stationary throughput in Mb/s:2UDP+2TCP and 2DCCP+2TCP
DCCP and TCP flows_1 Interactions between DCCP and TCP:TCP flow first
DCCP and TCP flows_2 Interactionsbetween DCCP and TCP: DCCP flow first
DCCP and TCP flows_3 Summary of stationary throughput in Mb/s: DCCP + TCP
Two DCCP flows_1 Interactionsbetween two DCCP flows
Effect of propagation delay Propagation delay γ versus throughput : b=20 packet
Effect of bottlenecked router buffer size Buffer size versus throughput: γ = 10 ms
Conclusions • The bandwidth consumption of DCCP can be adjusted to accommodate TCP flows. • The fairness between TCP and DCCP flows depends heavily on RTT. • The fairness among DCCP flows is not satisfactory.
Reference • Datagram Congestion Control Protocol (RFC 4340) • CCID2-TCP-like Congestion Control (RFC 4341) • CCID3-TCP-Friendly Rate Control (TFRC) (RFC4342) • Performance Evaluations of DCCP for Bursty Traffic in Real-time Applications