1. B99705021 李奕德

2.  Abstract  Intro  ECN in DCTCP  TDCTCP  Performance evaluation  conclusion

3.  TCP does not fit in datacenter  DCTCP may lower throughput due to small buffer size  Improved version of DCTCP (called TDCTCP)  Compare to existed algorithm (DCTCP, TCPNewReno)  TDCTCP may have slightly higher delay but have much better throughput in general

4.  Abstract  Intro  ECN in DCTCP  TDCTCP  Performance evaluation  conclusion

5.  Data flow in datacenter: 1. large data flow require high throughput 2. small data flow require low latency  Incast problem

6.  TCP: provide : reliable, ordered byte stream does not provide: high throughput with “simultaneously low delay”  Other similar solutions:  DCTCP, TCPNewReno, TDCTCP  Tested under OMNeT++ simulator

7.  Abstract  Intro  ECN in DCTCP  TDCTCP  Performance evaluation  conclusion

8.  ECN mechanism  2-bit used to describe current situation 00: Non ECN-Capable Transport — Non-ECT 10: ECN Capable Transport — ECT(0) 01: ECN Capable Transport — ECT(1) 11: Congestion Encountered — CE

9.  Abstract  Intro  ECN in DCTCP  TDCTCP  Performance evaluation  conclusion

10.  A. Modification of Congestion Avoidance  B. Resetting α after Delayed ACK timeout  C. Dynamic Delayed ACK timeout calculation

11.  Modification of Congestion Avoidance  α = fraction of marked packets in one congestion window  Indicates current congestion level  MSS = Maximum Segment Size  Indicates the size of data that can be sent

13.  Resetting α after Delayed ACK timeout  delayed ACK timeout: use in TCP to reduce ACKs send to the sender  When ACK timeout occur: 1. α is not updated 2. Old α remain high and block increment of window size  α is reset to 0 after every delayed ACK timeout

14. Set α to 0 when this happen

15.  Dynamic Delayed ACK timeout calculation  DCTCP: small buffer = small congestion window  Congestion window reduce to 1, causing ACK timeouts

16.  Packet arrival follows an exponential distribution  Packet loss probability in the network is small

17.  Use 10 flows to demonstrate Low variance in window size Spend less time in ACK timeout

18.  Abstract  Intro  ECN in DCTCP  TDCTCP  Performance evaluation  conclusion

19.  Throughput  Fairness  Delay  Queue length  Variation in Delay  Variation in Throughput

20.  Environment

21.  Throughput - single bottleneck, 1Gbps  Better performance than DCTCP in general

22.  Throughput - single bottleneck, 10Gbps  Better than DCTCP under smaller K  Provide same throughput as TCPNewReno in early stages

23.  Throughput – multi-bottleneck, 10Gbps  Better than DCTCP under smaller K  Provide same throughput as TCPNewReno in early stages

24.  Fairness- single bottleneck, measure in JFI  better fairness in every scenario

25.  Fairness- multi-bottleneck, measure in JFI

26.  Delay- single bottleneck, 10 Gbps  TCPNewReno is good except high delay

27.  Delay- multi-bottleneck, 10 Gbps

28.  Queue length  TDCTCP is slightly longer than DCTCP

29.  Variation in Delay

30.  Variation in throughput

31.  Abstract  Intro  ECN in DCTCP  TDCTCP  Performance evaluation  conclusion

32.  Modified DCTCP => TDCTCP  15% higher throughput than DCTCP  improved fairness compare to DCTCP  provides more stable throughput  queue length is slightly more than that of DCTCP at 10Gbps  delay is slightly higher than that of DCTCP

33. Any questions??