Fleksibilni Internet servisi na bazi kontrole kašnjenja i

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elevated network, a real-time application has high probability to actually receive lower delay than in a best-effort network even though not every router in the network supports the non-elevated mechanisms. Moreover, price for this service is the same as for the best- effort service. Various properties of Integrated, Differentiated, and Non-elevated Services are summarized in Table 1. Granularity of service guarantees Type of service guarantees Scope of service guarantees Table 1. Comparison of service differentiation models. Integrated Services individual flows absolute Differentiated Services flow aggregates (classes) absolute or relative 15 Non-Elevated Services flow aggregates (classes) relative end-to-end per-hop per-hop State in routers per-flow per-class not required Admission control Resource reservation All-or-nothing upgrade required required required for absolute differentiation required for absolute differentiation not required not required required required not required Before presenting a new architecture for non-elevated services, in Section 3 we describe several existing proposals.
3. Survey of existing proposals for non-elevated services There are currently three proposed architectures for non-elevated services: Alternative Best-Effort (ABE) [3], Best-Effort Differentiated Services (BEDS) [4], and Equivalent Differentiated Services (EDS) [5]. We describe here mechanisms employed in these architectures and address some of their drawbacks. 3.1. Alternative Best-Effort (ABE) ABE [3] introduced two traffic classes: a low delay class named “green” and a “blue” class that corresponds to the best-effort class. Green packets are guarantied low bounded delay, while blue traffic receives at least as much throughput as it would receive in a flat best-effort network. In order to ensure that “green does not hurt blue”, two conditions must hold: local transparency and throughput transparency for blue packets. Local transparency assumes that the delay experienced by blue packets in ABE is not higher than the delay they would experience in a best-effort network. Furthermore, a blue packet is not discarded if it would not be discarded in a best-effort network. Throughput transparency implies that blue flows receive at least the same throughput as they would receive in a best-effort network. ABE provides local transparency for blue, while throughput transparency condition is considered to be loose. A router implementation of ABE called Duplicate Scheduling with Deadlines (DSD) [3] is illustrated in Fig. 3. Duplicates of all incoming packets are sent to a virtual queue and accepted if the virtual buffer is not full. The duplicates in the virtual queue are served according to the first-in first-out (FIFO) discipline, as they would be served in a 16
Page 1 and 2: UNIVERZITET U BEOGRADU ELEKTROTEHNI
Page 3 and 4: Abstract Vladimir V. Vukadinović D
Page 5 and 6: Table of Contents Abstrakt.........
Page 7 and 8: List of Figures Fig. 1. Traffic con
Page 9 and 10: List of Tables Table 1. Comparison
Page 11 and 12: IntServ Integrated Services IP Inte
Page 13 and 14: The DiffServ model [8]-[10] offers
Page 15 and 16: [29]. Detailed description of these
Page 17 and 18: 2. Quality of Service in Internet:
Page 19 and 20: whose sole purpose is to detect and
Page 21 and 22: architectures (implemented or propo
Page 23 and 24: 2.2.2. Differentiated Services (Dif
Page 25: 2.2.3. Non-Elevated Services Non-El
Page 29 and 30: RED [29] is an active queue managem
Page 31 and 32: The intersections of the RED contro
Page 33 and 34: flows. Quality of services received
Page 35 and 36: normalized loss rates among classes
Page 37 and 38: 4. Proposed service differentiation
Page 39 and 40: controller can be considered as an
Page 41 and 42: to a close-to-optimal rate assignme
Page 43 and 44: Fig. 8. Example of an input and out
Page 45 and 46: where I DS ( τ ) Z ( τ ) = . If (
Page 47 and 48: packet departure as: V V TS DS d
Page 49 and 50: 5.3.1. Influence of traffic load In
Page 51 and 52: differentiation. Similar result has
Page 53 and 54: In order to investigate the perform
Page 55 and 56: schedulers for proportional delay d
Page 57 and 58: 6. Packet Loss Controller Packet Lo
Page 59 and 60: described by Floyd and Jacobson [29
Page 61 and 62: where R’ and p’ are round-trip
Page 63 and 64: Since σ=σ0 ensures that T=T’, i
Page 65 and 66: ⎛ ⎜ ⎝ Based on (51) - (54),
Page 67 and 68: 7. Simulation results We evaluated
Page 69 and 70: BPR scheduling without PLC, TCP flo
Page 71 and 72: time of TCP packets continually inc
Page 73 and 74: Fig. 27. Influence of UDP load on T
Page 75 and 76: even in the case of multiple bottle
Page 77 and 78:
management, PLC controller and TCP
Page 79 and 80:
Appendix A The pseudocode for the h
Page 81 and 82:
Appendix B We describe here a proce
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Fig. 30. TCP throughput as a functi
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2 ⎛ 2 ⎞ 5 ⎛ 2 ⎞ 1 ⎛ ⎞
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+Queue/PROBE set wait_ true +Queue/
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}; #endif int idle_; /* queue is id
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} if (!dsQueue.head() && tsQueue.he
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* count and count_bytes keeps a tal
Page 95 and 96:
int PROBEQueue::length(int qos_clas
Page 97 and 98:
[13] S. Bodamer, “A new schedulin
Page 99 and 100:
[37] K. Nichols, S. Blake, F. Baker
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Fleksibilni Internet servisi na bazi kontrole kašnjenja i

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