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

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i) at least Mrm in-rate cells have been sent and at least Trm time has elapsed, or ii) Nrm -1 in-rate cells have been sent. b) The next in-rate cell shall be a backward RM-cell if condition (a) above is not met, if a backward RM cell is waiting for transmission, and if either: i) no in-rate backward RM-cell has been sent since the last in-rate forward RM-cell, or ii) no data cell is waiting for transmission. c) The next in-rate cell sent shall be a data cell if neither condition (a) nor condition (b) is met, and if a data cell is waiting for transmission. 4. Cells sent in accordance with source behaviors #1,#2, and #3 shall have CLP=0. 5. Before sending a forward in-rate RM cell, if ACR > ICR and the time T that has elapsed since the last in-rate forward RM-cell was sent is greater than ADTF, then ACR shall be reduced to ICR. 6. Before sending an in-rate forward RM cell, and following behavior #5 above, if at least CRM in-rate forward RM-cells have been sent since the last backward RM-cell with BN=0 was received, then ACR shall be reduced by at least ACR CDF, unless that reduction would result in a rate below MCR, in which case ACR shall be set to MCR. 381
7. After following behaviors #5 and #6 above, the ACR value shall be placed in the CCR eld of the outgoing forward RM-cell, but only in-rate cells sent after the outgoing forward RM-cell need to follow the new rate. 8. When a backward RM-cell (in-rate or out-of-rate) is received with CI=1, then ACR shall be reduced by at least ACR RDF, unless that reduction would result in a rate below MCR, in which case ACR shall be set to MCR. If the backward RM-cell has both CI=0 and NI=0, then the ACR may be increased by no more than RIF PCR, to a rate not greater than PCR. If the backward RM-cell has NI=1, the ACR shall not be increased. 9. When a backward RM-cell (in-rate or out-of-rate) is received, and after ACR is adjusted according to source behavior #8, ACR is set to at most the minimum of ACR as computed in source behavior #8, and the ER eld, but no lower than MCR. 10. When generating a forward RM-cell, the source shall assign values to the various RM-cell elds as speci ed for source-generated cells in Table 5-4. 11. Forward RM-cells may be sent out-of-rate (i.e., not conforming to the current ACR). Out-of-rate forward RM-cells shall not be sent at a rate greater than TCR. 12. A source shall reset EFCI on every data cell it sends. 13. The source may implement a use-it-or-lose-it policy to reduce its ACR to a value which approximated the actual cell transmission rate. Use-it-or-lose-it policies are discussed in Appendix I.8. 382
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Tra c Management for the Available
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ABSTRACT With the merger of telecom
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Tra c Management for the Available
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To my family iv
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VITA April 30, 1971 :::::::::::::::
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2.7 Switch Behavior . . . . . . . .
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5.8 Proof: Fairness Algorithm Impro
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8.15 Factors A ecting Bu ering Requ
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Bibliography . . . . . . . . . . .
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8.12 Maximum Queues for Satellite N
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5.1 Transmitted cell rate (instanta
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6.13 Results foratwo sources con gu
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7.11 E ect of UILI on Medium Bursts
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C.3 Flow Chart of Bi-Directional Co
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header information which limits the
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switches since a standard does not
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congestion control deals with the c
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hand side of the equation is the su
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analyses which are used to validate
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CHAPTER 2 THE ABR TRAFFIC MANAGEMEN
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time (RTT). As we explain later, AB
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feedback from nearby switches to re
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Note that in-rate and out-of-rate d
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Data cells also have an Explicit Fo
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opportunity the source may nd that
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Figure 2.7: Scheduling of forward R
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as the timeout value) which reduces
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It has been incorrectly believed th
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NI CI Action 0 0 ACR Min(ER, ACR +
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Source Rule 13: Sources can optiona
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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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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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Page 359 and 360: On the other hand, if the applicati
Page 361 and 362: of managing bu ers, queueing, sched
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Page 365 and 366: call such a switch a \VS/VD switch"
Page 367 and 368: Figure 9.2: Per-class queues in a n
Page 369 and 370: which arises is where the rate calc
Page 371 and 372: 9.2 The ERICA Switch Scheme: Renota
Page 373 and 374: The unknowns in the above equations
Page 375 and 376: Figure 9.9: Two methods to measure
Page 377 and 378: 9.4 VS/VD Switch Design Options 9.4
Page 379 and 380: # VC Rate VC Input Rate Input Rate
Page 381 and 382: 8 uses source rate measurement, we
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Page 385 and 386: sources in chapter 6. We expect the
Page 387 and 388: con guration mentioned in the table
Page 389 and 390: can be very di erent for di erent V
Page 391 and 392: CHAPTER 10 IMPLEMENTATION ISSUES At
Page 393 and 394: With an enhanced UBR service, appli
Page 395 and 396: 2. Some switch schemes have a proce
Page 397 and 398: 4. Large legacy switches have a pro
Page 399 and 400: section 9. Further, WAN switches wo
Page 401 and 402: CHAPTER 11 SUMMARY AND FUTURE WORK
Page 403 and 404: good transient performance. Since r
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Page 407: APPENDIX A SOURCE, DESTINATION AND
Page 411 and 412: set the QL and SN elds to zero, pre
Page 413 and 414: d) VS/VD Control: The switch may se
Page 415 and 416: 5. Setting of other parameters at V
Page 417 and 418: 4. The averaging interval timer exp
Page 419 and 420: 1. Initialization: Target Cell Rate
Page 421 and 422: THEN IF (OCR In Cell Fair Share Rat
Page 423 and 424: APPENDIX C ERICA SWITCH ALGORITHM:
Page 425 and 426: Number Active VCs In Last Interval
Page 427 and 428: IF (NOT(Averaging VCs Option)) THEN
Page 429 and 430: IF (Load Factor = In nity) THEN Loa
Page 431 and 432: ; (Contribution[VC] = Decay Factor)
Page 433 and 434: Name Explanation Flow Chart (FC) or
Page 435 and 436: Figure C.2: Flow Chart for Achievin
Page 437 and 438: Figure C.4: Flow Chart of averaging
Page 439 and 440: Figure C.6: Flow chart of averaging
Page 441 and 442: C.3 Pseudocode for VS/VD Design Opt
Page 443 and 444: (* | Bottleneck rate of next loop |
Page 445 and 446: Follow SESRules 1-4 (see appendix A
Page 447 and 448: CRM - Missing RM-cell Count DIR bit
Page 449 and 450: TUB -Target Utilization Band Trm -
Page 451 and 452: [12] J. Bennett and G. Tom Des Jard
Page 453 and 454: [38] M. Grossglauser, S.Keshav, and
Page 455 and 456: [64] H. T. Kung. Flow Controlled Vi
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