An Investigation into Transport Protocols and Data Transport ...

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8.2. Test Calibration 150 In order to obtain a good representation of the range of performance metrics, all tests were repeated 5 times and the arithmetic mean taken. The error on each measurement was taken as the standard error from this mean [Boa83] and is presented in all plots. Furthermore, due to the prevalence of FIFO queuing mechanisms in use on the Internet, the study is limited to drop-tail environments to gauge the worse case scenario whereby network feedback is limited only by buffer overflows. 8.2 Test Calibration 8.2.1 Response Function The validation of the altAIMD algorithm and the representative New-TCP algorithms is shown in Figure 8.1. It shows the theoretical and measured response function of a single New-TCP flow (See Section 5.4.2) under the dummynet test network. The loss rate was controlled by the dummynet p variable that defines the average random loss rate experienced through a dummynet pipe. It can be seen that the measured results match very well to the theoretical predictions as specified by the respective New-TCP authors. The most notable deviation is that for both ScalableTCP and HSTCP, where there is a gradual, rather than immediate switch from their low speed modes to their high speed modes; this is represented by their increased goodputs over the regions of the switch. This was found to be due to the mode switching from Standard TCP into their representative high speed modes (this does not apply to FAST or H-TCP) as cwnd values approach their relevant thresholds. For HSTCP (Figure 8.2(a)), it was observed that the actual average cwnd
8.2. Test Calibration 151 Goodput (mbit/sec) 1000 100 10 1 Standard TCP BicTCP HSTCP HTCP ScalableTCP Standard TCP Theory HSTCP Theory ScalableTCP Theory 0.1 1e-07 1e-06 1e-05 1e-04 0.001 0.01 0.1 1 Random Packets Loss Rate (per packet) Figure 8.1: Effect of varying the dummynet random loss probability on a single TCP flow (250Mbit/sec, 162ms RTT, Bottleneck queue-size 20% BDP). cwnd and sthresh (packets) 250 200 150 100 50 cwnd ssthresh Theoretical average cwnd Actual average cwnd cwnd and ssthresh (packets) 50 40 30 20 10 cwnd ssthresh Theoretical average cwnd Actual average cwnd 0 0 100 200 300 400 500 600 Time (seconds) (a) HSTCP at p = 0.001 0 0 100 200 300 400 500 600 Time (seconds) (b) ScalableTCP at p = 0.005 Figure 8.2: Magnification of New-TCP mode switch from low-speed into highspeed modes (250Mbit/sec, 162ms RTT, queue-size 20% BDP). value of 65 packets is actually a lot higher than the theoretical prediction of 38 packets. As the cwnd is directly related to the goodput achieved by the TCP flow (Equation 4.1), it is unsurprising from this that the goodput is higher than the prediction allows. A factor that contributes to the larger value of cwnd is that cwnd is held as an integer under Linux; this causes a
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An Investigation into Transport Pro
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Contents List of Figures . . . . .
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Contents 5 4.6 Summary . . . . . .
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Contents 7 8.2 Test Calibration . .
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Contents 9 10.3.5 Further Tests . .
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List of Figures 11 5.7 Effect on cw
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List of Figures 13 8.16 Unfairness
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List of Figures 15 8.32 Friendlines
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List of Figures 17 9.19 Dynamic swi
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List of Figures 19 D.1 Internet pat
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List of Tables 21 A.1 Hardware and
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Publications And Workshops Some of
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1.2. Research Scope 25 • Identifi
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1.4. Dissertation Outline 27 • Id
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Chapter 2 High Energy Particle Phys
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2.2. Analysis Methods 31 the data i
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2.3. Data Volumes and Regional Cent
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2.3. Data Volumes and Regional Cent
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2.4. Data Transfer Requirements 37
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2.5. Summary 39 data, the most impo
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3.1. Data Intercommunication 41 mov
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3.2. Network Monitoring 43 Whilst l
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3.2. Network Monitoring 45 Internet
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3.2. Network Monitoring 47 1 0.8 Bo
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Chapter 4 Transmission Control Prot
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4.1. Overview 51 Throughput Delay L
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4.2. Protocol Description 53 is dep
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4.2. Protocol Description 55 As a r
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4.3. Congestion Control 57 excessiv
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4.3. Congestion Control 59 probe fo
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4.4. Retransmission Timeout 61 tion
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4.5. TCP Variants 63 mechanisms are
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4.5. TCP Variants 65 connection ini
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4.5. TCP Variants 67 20 15 cwnd sst
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4.5. TCP Variants 69 no more acks t
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4.5. TCP Variants 71 [Hoe96]. In bo
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4.5. TCP Variants 73 TCP Timestamps
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4.6. Summary 75 traffic for a parti
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Chapter 5 TCP For High Performance
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5.1. TCP Hardware Requirements 79 G
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5.1. TCP Hardware Requirements 81 1
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5.1. TCP Hardware Requirements 83 C
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5.2. TCP Tuning & Performance Impro
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5.3. Network Aid in Congestion Dete
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Page 101 and 102: 5.4. Analysis of AIMD Congestion Co
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Page 111 and 112: 6.1. Survey of New-TCP Algorithms 1
Page 125 and 126: 6.2. Discussion and Deployment Cons
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Page 135 and 136: Chapter 7 Testing Framework for the
Page 137 and 138: 7.1. Metrics 137 various New-TCP al
Page 139 and 140: 7.1. Metrics 139 assuming equilibri
Page 141 and 142: 7.2. Environment 141 of packets in
Page 143 and 144: 7.2. Environment 143 T 0 B, T T 1 F
Page 145 and 146: Chapter 8 Systematic Tests of New-T
Page 147 and 148: 8.1. Methodology 147 fed into the d
Page 149: 8.1. Methodology 149 Various other
Page 153 and 154: 8.2. Test Calibration 153 cwnd and
Page 155 and 156: 8.2. Test Calibration 155 100 1 Agg
Page 157 and 158: 8.2. Test Calibration 157 1000 FAST
Page 159 and 160: 8.3. Results 159 10 100 Total Throu
Page 161 and 162: 8.3. Results 161 14 12 HSTCP 1 α H
Page 163 and 164: 8.3. Results 163 cwnd (packets) 120
Page 165 and 166: 8.3. Results 165 Fraction Bytes Ret
Page 167 and 168: 8.3. Results 167 1200 1000 HTCP 1 H
Page 169 and 170: 8.3. Results 169 This is due to the
Page 171 and 172: 8.3. Results 171 4000 3500 3000 HTC
Page 173 and 174: 8.3. Results 173 800 700 600 Standa
Page 175 and 176: 8.3. Results 175 1 1 Fairness Ratio
Page 177 and 178: 8.3. Results 177 10 100 Total Throu
Page 179 and 180: 8.3. Results 179 1000 Standard TCP
Page 181 and 182: 8.3. Results 181 600 500 Standard T
Page 183 and 184: 8.4. Discussion of Results 183 Asym
Page 185 and 186: 8.4. Discussion of Results 185 New-
Page 187 and 188: 8.4. Discussion of Results 187 Asym
Page 189 and 190: 8.5. Summary 189 The importance of
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9.1. Transfer Tests Across Dedicate
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9.2. Preferential Flow Handling Usi
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9.3. Internet Transfers 229 can cau
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9.3. Internet Transfers 231 Stanfor
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9.3. Internet Transfers 233 10 1 St
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9.3. Internet Transfers 235 1000 90
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9.3. Internet Transfers 237 Fractio
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9.3. Internet Transfers 239 10000 c
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9.3. Internet Transfers 241 achieve
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9.4. Summary 243 performance of sin
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9.4. Summary 245 Nevertheless, a Di
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10.1. Summary 247 PCs. But at 1Gb/s
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10.2. New-TCP Suitability Study 249
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10.2. New-TCP Suitability Study 251
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10.3. Future Directions 253 low ove
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10.3. Future Directions 255 porates
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10.3. Future Directions 257 A more
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10.4. Conclusion 259 This dissertat
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A.1. Data Storage 261 with the choi
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A.1. Data Storage 263 gether with h
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A.1. Data Storage 265 The virtual m
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A.1. Data Storage 267 Read Speed (M
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A.1. Data Storage 269 Read Speed (M
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A.1. Data Storage 271 1600 1600 140
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A.2. Network Interface Cards 273 la
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A.2. Network Interface Cards 275 de
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A.2. Network Interface Cards 277 of
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A.2. Network Interface Cards 279 PC
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A.2. Network Interface Cards 281 70
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A.2. Network Interface Cards 283 Th
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A.2. Network Interface Cards 285 20
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A.2. Network Interface Cards 287 ha
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B.2. Wide Area Network Tests 289 Da
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C.3. DataTAG 291 Cisco 7606 Cisco 7
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Appendix D Network Paths of Interne
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295 ham02gva.datatag.org:192.91.239
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Bibliography 297 [All03] [AMA + 99]
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Bibliography 299 [BPSK96] H. Balakr
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Bibliography 301 [DC02] [ea02] [FF9
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Bibliography 303 [Flo03] [Flo04] S.
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Bibliography 305 [Hoe96] [IET] [Jac
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Bibliography 307 [KRB05] [Lah00] [L
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Bibliography 309 [MHR03] [MM96] M.
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Bibliography 311 [Pos81a] J. Postel
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Bibliography 313 [tePM] IEPM Intern
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