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Advanced Internet Research Wim Sjouw Santiago de Compostela 14 February 2003.

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Presentation on theme: "Advanced Internet Research Wim Sjouw Santiago de Compostela 14 February 2003."— Presentation transcript:

1 Advanced Internet Research Wim Sjouw Santiago de Compostela 14 February 2003

2 TCP behavior on Trans-Atlantic lambda’s Wim Sjouw, Antony Antony, Hans Blom, Cees de Laat, Jason Lee EU - IST DataTag project, WP3

3 Advanced Internet Research Wim Sjouw Santiago de Compostela 14 February 2003 LFNT

4 Advanced Internet Research Wim Sjouw Santiago de Compostela 14 February 2003

5 Long: RTT > 50 msec

6 Advanced Internet Research Wim Sjouw Santiago de Compostela 14 February 2003

7 FAT B > 622 Mbps

8 Advanced Internet Research Wim Sjouw Santiago de Compostela 14 February 2003

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10 Surprise TCP throughput 90 Mbps

11 Advanced Internet Research Wim Sjouw Santiago de Compostela 14 February 2003 UDPmon Probe the network with trains of UDP packets Packets are: numbered & time stamped

12 variable number of packets varable packet length variable inter packet delay Advanced Internet Research Wim Sjouw Santiago de Compostela 14 February 2003 UDPmon Probe the network with trains of UDP packets Very precise timing with Pentium proc. clock Packets are: numbered & time stamped

13 number of packets: 5000 packet length: 1000 Bytes inter packet delay: 0 μsec Advanced Internet Research Wim Sjouw Santiago de Compostela 14 February 2003 UDPmon Probe the network with trains of UDP packets Timing: 10 ns

14 Advanced Internet Research Wim Sjouw Santiago de Compostela 14 February 2003 UDPmon

15 Advanced Internet Research Wim Sjouw Santiago de Compostela 14 February 2003

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17 N b = 1500 N d = 0 l = 1000 f = 1 Gbps s = 622 Mbps then M = 0.5 MB

18 Advanced Internet Research Wim Sjouw Santiago de Compostela 14 February 2003

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20 R = 100 ms

21 Advanced Internet Research Wim Sjouw Santiago de Compostela 14 February 2003 Back to TCP TCP is bursty due to: sliding window protocol slow start algorithm

22 Advanced Internet Research Wim Sjouw Santiago de Compostela 14 February 2003

23 W= sent segments Y= advertised window G= ACK’s R= retransmits P= SACK’s

24 Advanced Internet Research Wim Sjouw Santiago de Compostela 14 February 2003

25 512 packets in 4 ms

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30 So overall pick from this menu: flow control traffic shaping RED (Random Early Discard)

31 Advanced Internet Research Wim Sjouw Santiago de Compostela 14 February 2003 Receiver: buffer capacity of NIC interupt latency & coalescence interupt overhead PCI bus width and PCI bus speed TCP stack overhead & complexity OS overhead

32 Advanced Internet Research Wim Sjouw Santiago de Compostela 14 February 2003 < Mac OS < Linux

33 Advanced Internet Research Wim Sjouw Santiago de Compostela 14 February 2003 Conclusions: ‘ old ’ TCP does not perform in a “Long Fat Network” UDP does perform, but unacceptable End system(s) dictate overall performance: o O.S o Memory o NIC

34 Advanced Internet Research Wim Sjouw Santiago de Compostela 14 February 2003 beware of

35 Advanced Internet Research Wim Sjouw Santiago de Compostela 14 February 2003

36 Thanks!

37 Advanced Internet Research Wim Sjouw Santiago de Compostela 14 February 2003

38 UDPmon: Richard Hughes Johnes


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