An Investigation into Transport Protocols and Data Transport ...

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9.1. Transfer Tests Across Dedicated Private Wide Area Networks 204 20 15 HSTCP HTCP ScalableTCP Unity 20 15 HSTCP HTCP ScalableTCP Unity Impact 10 Impact 10 5 5 0 1 10 Number of Standard TCP Flows 0 1 10 Number of Standard TCP Flows (a) 1 New-TCP Flow (b) 10 New-TCP Flow Figure 9.11: Impact of New-TCP flows on Standard TCP Bulk Traffic on DataTAG. tively fairer under the low latency network due to the low cwnd values associated with the bandwidth delay product of the MB-NG network. H-TCP, on the other hand, appears to be ‘too fair’ with the competing background traffic, by actually facilitating a higher goodput of the background traffic. This was found to be due to the slower cwnd increase of H-TCP while the congestion epoch time was small combined with the overly aggressive decrease implementation as a result of cwnd quantisation. Under DataTAG, it was readily observed that the larger cwnd values associated with the large bandwidth delay products increased the impact of the New-TCP flows. Surprisingly, H-TCP appears to be the most aggressive under single flows. Upon closer inspection of the cwnd traces, it was found that this was due to the severity of the cwnd decreases due to SACK processing and moderate_cwnd() which lowered goodput of both ScalableTCP and HSTCP. H-TCP was aided by the relatively faster convergence times which facilitate higher goodput, and hence also increased impact. With a larger number of New-TCP flows, these problems were alleviated due to smaller bandwidth delay products per flow, and clearly shows the
9.1. Transfer Tests Across Dedicated Private Wide Area Networks 205 aggressive impact of ScalableTCP. Both HSTCP and H-TCP appear to have similar impact properties, with H-TCP being a little bit more aggressive with larger numbers of Standard TCP flows. 9.1.7 Discussion of Results In order to better understand the lack of bandwidth utilisation of a single New-TCP flow when competing against CBR traffic (See Figure 9.3), Figure 9.12 shows the cwnd and goodput traces of the various New-TCP algorithms with 200Mbit/sec and 600Mbit/sec CBR background loads. For HSTCP, at low background loads and after congestion, the value of cwnd diminished below the value of ssthresh. It is this decrease in cwnd after congestion that lowers the goodput even though extra bandwidth is available. Similar results were observed for ScalableTCP. However, unlike HSTCP, there are intermittent periods whereby the cwnd actually drops to very low values and ScalableTCP has to grow cwnd all the way from very low values of cwnd upto the point of congestion. At lower goodputs, ScalableTCP is able to function appropriately, with a very small back-off per congestion event which results in a slightly higher goodput compared to the other algorithms. It was observed that H-TCP’s dynamic is not as severely affected under large bandwidths as that of ScalableTCP or HSTCP, which explains the slightly higher value of H-TCP under MB-NG. As the TCP specifications [Jac88] state that the cwnd should be set to the calculation of ssthresh upon congestion (plus 3 packets for the duplicate acknowledgments), is it surprising that the values of ssthresh for these tests show that there is no recalculation. This suggests that these drops in cwnd
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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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5.3. Network Aid in Congestion Dete
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5.4. Analysis of AIMD Congestion Co
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5.5. Summary 109 5.5 Summary Even t
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6.1. Survey of New-TCP Algorithms 1
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6.2. Discussion and Deployment Cons
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6.3. Summary 133 6.3 Summary The re
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Chapter 7 Testing Framework for the
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7.1. Metrics 137 various New-TCP al
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7.1. Metrics 139 assuming equilibri
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7.2. Environment 141 of packets in
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7.2. Environment 143 T 0 B, T T 1 F
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Chapter 8 Systematic Tests of New-T
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8.1. Methodology 147 fed into the d
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8.1. Methodology 149 Various other
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8.2. Test Calibration 151 Goodput (
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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
Page 191 and 192: 9.1. Transfer Tests Across Dedicate
Page 203: 9.1. Transfer Tests Across Dedicate
Page 215 and 216: 9.2. Preferential Flow Handling Usi
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Page 231 and 232: 9.3. Internet Transfers 231 Stanfor
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Page 243 and 244: 9.4. Summary 243 performance of sin
Page 245 and 246: 9.4. Summary 245 Nevertheless, a Di
Page 247 and 248: 10.1. Summary 247 PCs. But at 1Gb/s
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Page 251 and 252: 10.2. New-TCP Suitability Study 251
Page 253 and 254: 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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