copa擁塞控制仿真

 copa [1] is a congestion control algorithm propsed by MIT, targeting for low latency. It was implemented in mvfst[2], another quic protocol stack released by facebook。I test the peroformance of copa on ns3.
  A point point channel is built. The bandwidth is 3Mbps and one way propagation delay is 100 ms, the maximum queue delay is 300ms. Three flows are tested.
 When all three flows take copa as congestion control. The rate dynamic of each flow is given blow. The fairness is guaranteed.

 The one way delay of each received packet. And the lantency is also quite low.

 When the second flow takes BBR for rate control. From the below figure, BBR takes most bandwidth and the other two copa flow only maintain mimimum rate.

  The one way transmission delay of each flow:

 When the second flow takes Cubic for rate control. The rate dymamic of each flow:

 The one way transmission delay of each flow:

  Discussion: it seems the bandwidth competence of copa is not quite well when sharing link with BBR and Cubic.
[1] Copa: Practical Delay-Based Congestion Control for the Internet
[2] mvfst
[3] Facebook：對比COPA 與CUBIC，BBR v1在擁塞控制及視頻質量的表現