Traffic Management for the Available Bit Rate (ABR) Service in ...

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4.11.2 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 4.12 HKUST Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86 4.12.1 Key Techniques . . . . . . . . . . . . . . . . . . . . . . . . . 86 4.12.2 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 4.13 SP-EPRCA scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 4.13.1 Key Techniques . . . . . . . . . . . . . . . . . . . . . . . . . 88 4.13.2 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 4.14 Summary of Switch Congestion Control Schemes . . . . . . . . . . 91 4.14.1 Common Drawbacks . . . . . . . . . . . . . . . . . . . . . . 92 5. The Ohio State University (OSU) Scheme . . . . . . . . . . . . . . . . . 95 5.1 The Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 5.1.1 Control-Cell Format . . . . . . . . . . . . . . . . . . . . . . 96 5.1.2 The Source Algorithm . . . . . . . . . . . . . . . . . . . . . 98 5.1.3 The Switch Algorithm . . . . . . . . . . . . . . . . . . . . . 100 5.1.4 The Destination Algorithm . . . . . . . . . . . . . . . . . . 104 5.1.5 Initialization Issues . . . . . . . . . . . . . . . . . . . . . . . 104 5.2 Key Features and Contributions of the OSU scheme . . . . . . . . . 105 5.2.1 Congestion Avoidance . . . . . . . . . . . . . . . . . . . . . 105 5.2.2 Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 5.2.3 Use Measured Rather Than Declared Loads . . . . . . . . . 108 5.2.4 Congestion Detection: Input Rate vs Queue Length . . . . . 108 5.2.5 Bipolar Feedback . . . . . . . . . . . . . . . . . . . . . . . . 111 5.2.6 Count the Number of Active Sources . . . . . . . . . . . . . 112 5.2.7 Order 1 Operation . . . . . . . . . . . . . . . . . . . . . . . 113 5.2.8 Backward Congestion Noti cations Cannot Be Used to Increase113 5.3 Extensions of The OSU Scheme . . . . . . . . . . . . . . . . . . . . 114 5.3.1 Aggressive Fairness Option . . . . . . . . . . . . . . . . . . 114 5.3.2 Precise Fair Share Computation Option . . . . . . . . . . . 117 5.3.3 BECN Option . . . . . . . . . . . . . . . . . . . . . . . . . 119 5.4 Other Simple Variants of the OSU Scheme . . . . . . . . . . . . . . 121 5.5 Simulation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . 122 5.5.1 Default Parameter Values . . . . . . . . . . . . . . . . . . . 123 5.5.2 Single Source . . . . . . . . . . . . . . . . . . . . . . . . . . 123 5.5.3 Two Sources . . . . . . . . . . . . . . . . . . . . . . . . . . 125 5.5.4 Three Sources . . . . . . . . . . . . . . . . . . . . . . . . . . 125 5.5.5 Transient Sources . . . . . . . . . . . . . . . . . . . . . . . . 125 5.5.6 Parking Lot . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 5.5.7 Upstream Bottleneck . . . . . . . . . . . . . . . . . . . . . . 127 5.6 Results for WAN Con guration . . . . . . . . . . . . . . . . . . . . 130 5.7 Results with Packet Train Workload . . . . . . . . . . . . . . . . . 132 ix
5.8 Proof: Fairness Algorithm Improves Fairness . . . . . . . . . . . . . 138 5.8.1 Proof of Claim C1 . . . . . . . . . . . . . . . . . . . . . . . 139 5.8.2 Proof of Claim C2 . . . . . . . . . . . . . . . . . . . . . . . 141 5.8.3 Proof for Asynchronous Feedback Conditions . . . . . . . . 145 5.9 Current Tra c Management Speci cations vs OSU Scheme . . . . 147 5.10 Limitations and Summary of the OSU Scheme . . . . . . . . . . . . 148 6. The ERICA and ERICA+ Schemes . . . . . . . . . . . . . . . . . . . . . 153 6.1 The Basic ERICA Algorithm . . . . . . . . . . . . . . . . . . . . . 154 6.2 Achieving Max-Min Fairness . . . . . . . . . . . . . . . . . . . . . . 156 6.3 Fairshare First to Avoid Transient Overloads . . . . . . . . . . . . 157 6.4 Forward CCR Used for Reverse Direction Feedback . . . . . . . . . 159 6.5 Single Feedback in a Switch Interval . . . . . . . . . . . . . . . . . 160 6.6 Per-VC CCR Measurement Option . . . . . . . . . . . . . . . . . . 161 6.7 ABR Operation with VBR and CBR in the Background . . . . . . 163 6.8 Bi-directional Counting of Bursty Sources . . . . . . . . . . . . . . 164 6.9 Averaging of the Number of Sources . . . . . . . . . . . . . . . . . 165 6.10 Boundary Cases . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165 6.11 Averaging of the Load Factor . . . . . . . . . . . . . . . . . . . . . 166 6.12 Time and Count Based Averaging . . . . . . . . . . . . . . . . . . 168 6.13 Selection of ERICA Parameters . . . . . . . . . . . . . . . . . . . . 169 6.13.1 Target Utilization U . . . . . . . . . . . . . . . . . . . . . . 170 6.13.2 Switch Averaging Interval AI . . . . . . . . . . . . . . . . . 171 6.14 ERICA+: Queue Length as a Secondary Metric . . . . . . . . . . . 172 6.15 ERICA+: 100% Utilization and Quick Drain of Queues . . . . . . . 173 6.16 ERICA+: Maintain a \Pocket" of Queues . . . . . . . . . . . . . . 174 6.17 ERICA+: Scalability toVarious Link Speeds . . . . . . . . . . . . 174 6.18 ERICA+: Target Operating Point . . . . . . . . . . . . . . . . . . 175 6.19 The ERICA+ Scheme . . . . . . . . . . . . . . . . . . . . . . . . . 176 6.20 E ect of Variation on ERICA+ . . . . . . . . . . . . . . . . . . . . 180 6.21 Selection of ERICA+ Parameters . . . . . . . . . . . . . . . . . . . 182 6.21.1 Parameters a and b . . . . . . . . . . . . . . . . . . . . . . . 182 6.21.2 Target Queueing Delay T 0. . . . . . . . . . . . . . . . . . . 183 6.21.3 Queue Drain Limit Factor QDLF . . . . . . . . . . . . . . 185 6.22 Performance Evaluation of the ERICA and ERICA+ Schemes . . . 186 6.22.1 Parameter Settings . . . . . . . . . . . . . . . . . . . . . . . 187 6.22.2 E ciency . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188 6.22.3 Minimal Delay andQueue Lengths . . . . . . . . . . . . . . 189 6.22.4 Fairness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190 6.22.5 Transient and Steady State Performance . . . . . . . . . . . 192 6.22.6 Adaptation to Variable ABR Capacity . . . . . . . . . . . . 193 x
Page 1 and 2: Tra c Management for the Available
Page 3 and 4: ABSTRACT With the merger of telecom
Page 5 and 6: Tra c Management for the Available
Page 7 and 8: To my family iv
Page 9 and 10: VITA April 30, 1971 :::::::::::::::
Page 11: 2.7 Switch Behavior . . . . . . . .
Page 15 and 16: 8.15 Factors A ecting Bu ering Requ
Page 17 and 18: Bibliography . . . . . . . . . . .
Page 19 and 20: 8.12 Maximum Queues for Satellite N
Page 21 and 22: 5.1 Transmitted cell rate (instanta
Page 23 and 24: 6.13 Results foratwo sources con gu
Page 25 and 26: 7.11 E ect of UILI on Medium Bursts
Page 27 and 28: C.3 Flow Chart of Bi-Directional Co
Page 29 and 30: header information which limits the
Page 31 and 32: switches since a standard does not
Page 33 and 34: congestion control deals with the c
Page 35 and 36: hand side of the equation is the su
Page 37 and 38: analyses which are used to validate
Page 39 and 40: CHAPTER 2 THE ABR TRAFFIC MANAGEMEN
Page 41 and 42: time (RTT). As we explain later, AB
Page 43 and 44: feedback from nearby switches to re
Page 45 and 46: Note that in-rate and out-of-rate d
Page 47 and 48: Data cells also have an Explicit Fo
Page 49 and 50: opportunity the source may nd that
Page 51 and 52: Figure 2.7: Scheduling of forward R
Page 53 and 54: as the timeout value) which reduces
Page 55 and 56: It has been incorrectly believed th
Page 57 and 58: NI CI Action 0 0 ACR Min(ER, ACR +
Page 59 and 60: Source Rule 13: Sources can optiona
Page 61 and 62: Switch Rule 1: This rule speci es t
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Observe that the ABR tra c manageme
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complex method like per-VC queuing
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graphs have a steady state with con
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Figure 3.2: Operating point between
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The following example illustrates t
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mention this concept of fairness fo
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control problem was also simpler. S
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of such an occurrence is expected t
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y giving only one feedback per meas
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CHAPTER 4 SURVEY OF ATM SWITCH CONG
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The adaptive FCVC algorithm [63] co
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np. Thus, long path VCs have fewer
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networks like ATM can have complete
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scheme followed by a discussion of
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exibility of decoupling the enforce
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4.6.1 Key Techniques In EPRCA, the
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If the mean ACR is not a good estim
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is the ratio of the input rate to t
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which shares the link equally as al
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proportional to the the unused ABR
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The key technique in the scheme is
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the bandwidth allocations to satis
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4.10 DMRCA scheme The Dynamic Max R
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on its CCR. Further MAX times out i
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other words, a di erent set of para
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A combination of several ideas in a
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4.13 SP-EPRCA scheme The SP-EPRCA s
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RTD and shuts o the source (for sta
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4.14.1 Common Drawbacks Though the
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The ATM Tra c Management standard a
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5.1.1 Control-Cell Format The contr
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The last two elds are used in the b
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Figure 5.3: Flow chart for updating
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LAF in cell Max(LAF in cell, z) The
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the time of departure (instant mark
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the steady state. The system operat
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5.2.3 Use Measured Rather Than Decl
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said about the maximum queue length
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The key problem with some unipolar
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Figure 5.6: Space time diagram show
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As noted, these heuristics do not g
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Transmitted Cell Rate ABR Queue Len
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4. The RM cell contains a timestamp
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1. The source o ered average cell r
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Transmitted Cell Rate Link Utilizat
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Figure 5.17: The parking lot fairne
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Figure 5.19: Network con guration w
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5.8 Proof: Fairness Algorithm Impro
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Region 2: y s and x s and U(1 + ) x
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eing divided into eight non-overlap
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Proof for Region 2 Triangular regio
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have: and y 0 = y(1 ; ) z x + y 0 =
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The OSU scheme is, therefore, incom
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workloads, where input load and cap
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(a) Regions used to prove Claim C1
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6.1 The Basic ERICA Algorithm The s
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A ow chart of the basic algorithm i
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efore competing sources can receive
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that the latest CCR information is
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the CCR value may not be an accurat
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(Target Utilization) (Link Bandwidt
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ABR Capacity Input Rate Overload Fa
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of arithmetic averaging used above.
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level of control. These parameters
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6.14 ERICA+: Queue Length as a Seco
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6.16 ERICA+: Maintain a \Pocket" of
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hence, introduces a new parameter,
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Figure 6.4: Linear functions for ER
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and Figure 6.6: The queue control f
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small averaging intervals. If the a
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The maximum value of T 0 also depen
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6.22 Performance Evaluation of the
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espectively. The target delay T 0 i
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6.22.4 Fairness Figure 6.9: Parking
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st link, VC 15 is limited to a thro
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From the gures, it is clear that ER
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counts the bursty source as active
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6.23 Summary of the ERICA and ERICA
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(a) Transmitted Cell Rate (c) Link
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(a) Transmitted Cell Rate (basic ER
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Page 243 and 244:
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RM cells. In this chapter, we devot
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low. This tradeo was discovered and
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in the speci cation. b) ACR shall n
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7.1.6 December 1995 Proposals There
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Figure 7.2: Multiplicative vsAdditi
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is never triggered. However, the PR
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simulation results of bursty source
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1. The time-based proposal also ind
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The switch maintains a local alloca
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PNI = f0, 1g : f1 ) No rule 5b, 0 )
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after reaching the goal. The time-b
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Figure 7.8: Closed-Loop Bursty Tra
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The algorithm measures the load and
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Medium Bursts Medium bursts are exp
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count-based technique may be insu c
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Figure 7.13: An event trace illustr
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CHAPTER 8 SUPPORTING INTERNET APPLI
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u ering which does not depend upon
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4 make it to the destination are ar
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Figure 8.3: At the ATM layer, the T
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issues and e ect of bursty applicat
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from the loss and they trigger the
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8.8 Performance Metrics We measure
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the performance is fair. Also, the
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Figure 8.7(b) shows the rates (ACRs
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Window Size in bytes vfive-tcp/opti
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The e ect of large bu ers on CLR is
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8.13 Summary of TCP/IP performance
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Feedback delay: Twice the delay fro
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on a link, two cells are expected a
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state only after the switch algorit
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queue length is less susceptible to
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to equalize rates for fairness, and
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QB = Link bandwidth (RT T ; T ) and
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u ered at the end-system, and not i
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Part b): When ABR load goes away, t
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All our simulations presented use t
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Averaging RTT(ms) Feedback Max Q Th
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a modi ed version of the ERICA algo
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ABR is better than UBR in these (en
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problems. During the ON time, the V
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hand, the frequency of the VBR is h
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like ERICA+ which uses the queueing
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minimum fairshare is low. This may
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8.17 E ect of Long-Range Dependent
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terminology) are called \Presentati
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The key point is that the MPEG-2 ra
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the MPEG-2 Transport Stream, and st
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8.17.4 Observations on the Long-Ran
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For the video sources, we choose me
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Video Sources ABR Metrics # Mean St
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However, with modi cations to ERICA
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Video Sources ABR Metrics # Avg Src
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Video Sources ABR Metrics # Avg Src
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On the other hand, if the applicati
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of managing bu ers, queueing, sched
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hence control the total load on the
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call such a switch a \VS/VD switch"
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Figure 9.2: Per-class queues in a n
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which arises is where the rate calc
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9.2 The ERICA Switch Scheme: Renota
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The unknowns in the above equations
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Figure 9.9: Two methods to measure
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9.4 VS/VD Switch Design Options 9.4
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# VC Rate VC Input Rate Input Rate
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8 uses source rate measurement, we
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The allocated rate update and the e
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sources in chapter 6. We expect the
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con guration mentioned in the table
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can be very di erent for di erent V
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CHAPTER 10 IMPLEMENTATION ISSUES At
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With an enhanced UBR service, appli
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2. Some switch schemes have a proce
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4. Large legacy switches have a pro
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section 9. Further, WAN switches wo
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CHAPTER 11 SUMMARY AND FUTURE WORK
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good transient performance. Since r
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variant background tra c conditions
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APPENDIX A SOURCE, DESTINATION AND
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7. After following behaviors #5 and
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set the QL and SN elds to zero, pre
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d) VS/VD Control: The switch may se
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5. Setting of other parameters at V
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4. The averaging interval timer exp
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1. Initialization: Target Cell Rate
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THEN IF (OCR In Cell Fair Share Rat
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APPENDIX C ERICA SWITCH ALGORITHM:
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Number Active VCs In Last Interval
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IF (NOT(Averaging VCs Option)) THEN
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IF (Load Factor = In nity) THEN Loa
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; (Contribution[VC] = Decay Factor)
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Name Explanation Flow Chart (FC) or
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Figure C.2: Flow Chart for Achievin
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Figure C.4: Flow Chart of averaging
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Figure C.6: Flow chart of averaging
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C.3 Pseudocode for VS/VD Design Opt
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(* | Bottleneck rate of next loop |
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Follow SESRules 1-4 (see appendix A
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CRM - Missing RM-cell Count DIR bit
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TUB -Target Utilization Band Trm -
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[12] J. Bennett and G. Tom Des Jard
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[38] M. Grossglauser, S.Keshav, and
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[64] H. T. Kung. Flow Controlled Vi
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