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B9820806 黃冠智. Outline OLDI(Online Data Intensive) architecture DCTCP(Datacenter TCP) D3(Deadline Driven Delivery) Protocol D2TCP(Deadline-Aware Datacenter.

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Presentation on theme: "B9820806 黃冠智. Outline OLDI(Online Data Intensive) architecture DCTCP(Datacenter TCP) D3(Deadline Driven Delivery) Protocol D2TCP(Deadline-Aware Datacenter."— Presentation transcript:

1 B9820806 黃冠智

2 Outline OLDI(Online Data Intensive) architecture DCTCP(Datacenter TCP) D3(Deadline Driven Delivery) Protocol D2TCP(Deadline-Aware Datacenter TCP) – Congestion avoidance algorithm Simulation Q&A

3 OLDI application Tree-based structure, divide-and-conquer algo Soft-real-time constraints(300 ms latency)

4 OLDI application Problems : – Maintain deadline will affect respond quality – Fan-in burst cause congestive packet drops and TCP retransmits Sols: – Over-provision the network link bandwidths(high cost) – increase the network’s time budget(degrades respond quality)

5 OLDI application Datacenter network also carry background flow which push control information and data to the node – Long-lived flows cause switch buffer to high utilization Package drop feedback Fair-share protocol

6 OLDI(Online Data Intensive) architecture DCTCP(Datacenter TCP) D3(Deadline Driven Delivery) Protocol D2TCP(Deadline-Aware Datacenter TCP) – Congestion avoidance algorithm Simulation Q&A

7 DCTCP AQM(Active Queue Management) scheme Using CE(Congestion Encountered) bit to control transmission rate ECN does not have suffice to solve fan-in burst problem – Aggregates one-bit ECN feedback and multiple RTTs to form multiple-bit metric

8 OLDI(Online Data Intensive) architecture DCTCP(Datacenter TCP) D3(Deadline Driven Delivery) Protocol D2TCP(Deadline-Aware Datacenter TCP) – Congestion avoidance algorithm Simulation Q&A

9 D3 Protocol The bandwidth request for the next RTT is piggybacked on the data packets of the current RTT Switch grant as much of the request as possible Far-deadline requests arriving slightly ahead of near-deadline requests

10 D3 Protocol Challenges – Requires custom switch ASICs (high cost low vol) – Cannot coexist with legacy TCP

11 The DC Network Protocol Should Meet OLDI deadlines, especially in fan-in- burst-induced congestion Achieve high bandwidth for background flows Work with existing switch hardware Be able to coexist with legacy TCP

12 OLDI(Online Data Intensive) architecture DCTCP(Datacenter TCP) D3(Deadline Driven Delivery) Protocol D2TCP(Deadline-Aware Datacenter TCP) – Congestion avoidance algorithm Simulation Q&A

13 D2TCP Meet OLDI deadlines, especially in fan-in- burst-induced congestion – Deadline-aware Achieve high bandwidth for background flows Work with existing switch hardware Be able to coexist with legacy TCP

14 Congestion avoidance algorithm is the fraction of packets that were marked with CE bits in the most recent window is the weight given to new samples d is the deadline imminence factor P is the penalty function applied to the window size W is congestion window

15 Congestion avoidance algorithm ≤ 1 and therefore, ≤ 1 d > 1 (near-deadline flows incur lower penalty) d < 1 (far-deadline flows incur higher penalty) d = 1 behavior matches DCTCP

16 Determining d is the time needed for a flow to complete transmitting D is the time remaining until its deadline expires

17 OLDI(Online Data Intensive) architecture DCTCP(Datacenter TCP) D3(Deadline Driven Delivery) Protocol D2TCP(Deadline-Aware Datacenter TCP) – Congestion avoidance algorithm Simulation Q&A

18 Simulation

19

20 TCP DCTCP D3 D2TCP

21 Background flows discuss

22 Missed deadline under tight deadline


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