Traffic Management for the Available Bit Rate (ABR) Service in ...
Traffic Management for the Available Bit Rate (ABR) Service in ... Traffic Management for the Available Bit Rate (ABR) Service in ...
N : The total number of ABR virtual circuits through the bottleneck (constant). qa(t) : the number of ABR cells at the bottleneck bu er at time t (qa(t) 0) na(t) : the number of active ABR sources at time t :(0 na(t) N) The \open-loop" system is de ned as follows. The bottleneck is loaded by both VBR and ABR. VBR is not controllable, whereas the ABR load and capacity display the following relation: na(t) X i=1 min(ri(t ; T i d)�di(t ; T i d)) = dqa(t) dt + a(t) Ca(t) The equation gives a relation between ABR demand, capacity, queues. and uti- lization. The left hand side of the equation is the aggregate ABR demand at time t. It is simply the sum of the demands of the active ABR sources ( Pna(t) i=1 ) staggered by their respective time delays ( = t ; T i d). Each ABR source demand is the minimum of the network-assigned rate (ri( )) and the desired source demand (di( )). The right 7
hand side of the equation is the sum of the rate of growth of the ABR queue ( dqa(t) dt ) and the capacity (Ca(t)) scaled by the utilization factor ( a(t)). In other words, the ABR demand directly a ects the ABR utilization and the rate of growth of the ABR queue. We desire that the system calculate and feedback rate assignments ri(t) which satisfy a desired set of goals. Since the goals are many, we elaborate the goals later in chapter 3. More generally, the problem we consider is the design of tra c management mechanisms for the ABR service. We consider ve aspects of this problem in this dissertation. Firstly, the service requires a mechanism to carry rate feedback from the switches to the sources. We also design switch algorithms which calculate the rate allocations ri(t) to satisfy a given set of goals. Secondly, we design a set of source mechanisms which respond to feedback, and perform control when feedback is disrupted or is stale. Thirdly, we validate the performance of the service for various ABR and VBR demand patterns (di(t) and dv(t)). Speci cally, we study the case of Internet tra c over ABR. Fourthly, we consider the switch design issues for a speci c ABR framework option called the \Virtual Source/Virtual Destination" option. The detailed problem speci cations and goals are considered in the respective portions of the dissertation. Our general methodology for tackling this problem is the use of experimentation and simulation techniques, rather than rigorous mathematical analysis. This tech- nique helps us build models which are closer to the real-world systems than math- ematical models. However, we rely on simple analytical tools and techniques (such as metric design, and correlation of feedback with control) to ensure stability ofthe designed system. 8
- 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 and 12: 2.7 Switch Behavior . . . . . . . .
- Page 13 and 14: 5.8 Proof: Fairness Algorithm Impro
- 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: congestion control deals with the c
- 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
- Page 63 and 64: Observe that the ABR tra c manageme
- Page 65 and 66: complex method like per-VC queuing
- Page 67 and 68: graphs have a steady state with con
- Page 69 and 70: Figure 3.2: Operating point between
- Page 71 and 72: The following example illustrates t
- Page 73 and 74: mention this concept of fairness fo
- Page 75 and 76: control problem was also simpler. S
- Page 77 and 78: of such an occurrence is expected t
- Page 79 and 80: y giving only one feedback per meas
- Page 81 and 82: CHAPTER 4 SURVEY OF ATM SWITCH CONG
- Page 83 and 84: The adaptive FCVC algorithm [63] co
N : The total number of <strong>ABR</strong> virtual circuits through <strong>the</strong> bottleneck (constant).<br />
qa(t) : <strong>the</strong> number of <strong>ABR</strong> cells at <strong>the</strong> bottleneck bu er at time t (qa(t) 0)<br />
na(t) : <strong>the</strong> number of active <strong>ABR</strong> sources at time t :(0 na(t) N)<br />
The \open-loop" system is de ned as follows. The bottleneck is loaded by both<br />
VBR and <strong>ABR</strong>. VBR is not controllable, whereas <strong>the</strong> <strong>ABR</strong> load and capacity display<br />
<strong>the</strong> follow<strong>in</strong>g relation:<br />
na(t) X<br />
i=1<br />
m<strong>in</strong>(ri(t ; T i d)�di(t ; T i d)) = dqa(t)<br />
dt + a(t) Ca(t)<br />
The equation gives a relation between <strong>ABR</strong> demand, capacity, queues. and uti-<br />
lization. The left hand side of <strong>the</strong> equation is <strong>the</strong> aggregate <strong>ABR</strong> demand at time t.<br />
It is simply <strong>the</strong> sum of <strong>the</strong> demands of <strong>the</strong> active <strong>ABR</strong> sources ( Pna(t)<br />
i=1 ) staggered by<br />
<strong>the</strong>ir respective time delays ( = t ; T i d). Each <strong>ABR</strong> source demand is <strong>the</strong> m<strong>in</strong>imum<br />
of <strong>the</strong> network-assigned rate (ri( )) and <strong>the</strong> desired source demand (di( )). The right<br />
7
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