F. M. Chiussi and V. Sivaraman, "Achieving high utilization in guaranteed services networks using early-deadline-first scheduling," Proc. IEEE IWQoS, 1998.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....queueing system. In many cases the performance can be numerically calculated as the cell delay distribution PDF (d) in stationarity. More complex schedulers have evolved for the need to treat distinct traffic streams differently. Here we concentrate only on the most promising algorithm EDF y [29], 30] because the principal properties of VOQ scheduling are to be shown. EDF offers a parameter D[V C] which has the meaning of deadline. With a y FCFS=first come first served [28] EDF=earliest deadline first. SCHOENEN: AN ARCHITECTURE SUPPORTING QOS IN VOQ SWITCHES 9 maxCTD s 1 Rate ....

F. Chiussi and V. Sivaraman, "Achieving High Utilization in Guaranteed Services Networks using Earliest-DeadlineFirst Scheduling," in Proceedings of the International Workshop on QoS, 1998.

....share of the bandwidth during congestion and offers an average service rate proportional to w[VC] The lower complexity approximations of WFQ, WRR 3 [5] and RR 3 (unweighted) are assumed here. The other family offers a parameter D[VC] which has the meaning of deadline. The algorithm EDF 3 [3, 9] is known to be optimum in the sense that it minimizes the total probability of exceeding the deadlines for all streams. With a properly chosen parameter D[VC] d max [VC] c this very successfully guarantees individual delay bounds 4 statistically. The complexity of EDF due to its ....

....for all streams. With a properly chosen parameter D[VC] d max [VC] c this very successfully guarantees individual delay bounds 4 statistically. The complexity of EDF due to its timestamp sorter can be 4 these are much tighter than worst case bounds and allow for the highest utilization [3] reduced by its approximation RPQ [11, 10] with any precision. These schedulers have been evaluated and simulated in a traditional OQ environment for later comparison with their VOQ counterpart. For the graphs shown in this paper a 16x16 switch has been symmetrically loaded with Poisson traffic ....

F. Chiussi and V. Sivaraman. Achieving High Utilization in Guaranteed Services Networks using Earliest-Deadline-First Scheduling. In Proceedings of the International Workshop on QoS, 1998.

....to show that in many cases, the performance of CEDF and GPS is close to the analytical bounds, implying that CEDF outperforms GPS. This work was extended to the case of arbitrary end to end delay bounds (i.e. independent of ae i ) in [3] Other work on Earliest Deadline First scheduling includes [5], 8] 9] 16] 20] In [7] Elwalid, Mitra and Wentworth analyzed statistical multiplexing in the context of FIFO scheduling. This analysis was then adapted for the case of GPS by Elwalid and Mitra in [6] and Kumaran, Margrave, Mitra and Stanley in [13] They characterize a session by its ....

F. Chiussi and V. Sivaraman. Achieving high utilization in guaranteed services networks using early-deadline-first scheduling. In Proceedings of the 6th IEEE/IFIP International Workshop on Quality of Service (IWQoS '98), May 1998.

....to show that in many cases, the performance of CEDF and GPS is close to the analytical bounds, implying that CEDF outperforms GPS. This work was extended to the case of arbitrary end to end delay bounds (i.e. independent of ) in [3] Other work on Earliest Deadline First scheduling includes [5], 8] 9] 16] 20] In [7] Elwalid, Mitra and Wentworth analyzed statistical multiplexing in the context of FIFO scheduling. This analysis was then adapted for the case of GPS by Elwalid and Mitra in [6] and Kumaran, Margrave, Mitra and Stanley in [13] They characterize a session by its ....

F. Chiussi and V. Sivaraman. Achieving high utilization in guaranteed services networks using early-deadline-first scheduling. In Proceedings of the 6th IEEE/IFIP International Workshop on Quality of Service (IWQoS '98), May 1998.

....pros and cons of workconserving and non workconserving scheduling. The scheduler is referred to as Earliness based EDF(EEDF) In EDF, each packet is timestamped with a deadline set equal to the sum of its arrival time and a delay bound, and packets are transmitted in increasing order of deadlines [5, 10, 11, 12, 13, 16, 24]. For a service where all packets satisfy worst case end to end delay bounds [6, 10] EDF has been shown to have optimal efficiency, in that it, among all scheduling disciplines, supports the most sessions with delay guarantees [12, 16] The admission control conditions for EDF, which verifies ....

....if and only if for all t D 1 : R Delta t X i2C A i (t Gamma D i ) max D j t L j (5) where R is the transmission rate of the scheduler, and L j is the maximum transmission time of a packet from flow j. More efficient versions of the admission control conditions have been derived in [5, 11]. In the past, both work conserving and non workconserving versions of EDF have been employed. The Tenet protocol suite [2] uses a workconserving version of EDF, referred to as Delay EDD. Here, the deadline dl i (t) for a packet arrival at time t of a flow i with delay bound D i is calculated ....

F. Chiussi and V. Sivaraman. Achieving High Utilization in Guaranteed Services Networks using EarlyDeadline -First Scheduling. In Proc. 6th IEEE/IFIP International Workshop on Quality of Service (IWQoS '98), May 1998.

....analysis and its extension to the multi node scenario in the presence of reshaping. Numerical results are presented in section V, while section VI summarizes the work. II. BACKGROUND We briefly review some of the concepts related to EDF scheduling, and recall the deterministic framework of [11] [2]. The EDF scheduling discipline [8] 22] works as follows: each connection i at switch m is associated with a local delay bound d i ; then, an incoming packet of connection i arriving to the scheduler at time t is stamped with a deadline t d i , and packets in the scheduler are served by ....

....scheduler delay bound at the m th switch for connection i. Note that the maximum shaper delay is incurred only once, and is independent of the number of nodes on the path. Equation (2) in conjunction with the single node CAC derived from (1) above readily leads to an end to end CAC framework [11] [2]. Once an appropriate shaper envelope E i has been chosen, the delay incurred in the shaper is computed. The remaining delay is split among the schedulers on the path of the connection, and the connection is admitted if the single node CAC at each switch admits the connection. The deterministic ....

[Article contains additional citation context not shown here]

F. M. Chiussi and V. Sivaraman. Achieving high utilization in guaranteed services networks using early-deadline-first scheduling. In International Workshop on Quality of Service, pages 209--217, Napa, California, May 1998.

....[12] in terms of the schedulable region for a set of flows with given deterministic delay requirements. EDF scheduling in conjunction with per hop traffic shaping (together referred to as Rate Controlled EDF or RC EDF) permits the provision of end to end delay guarantees [23] and work in [10] [1] has shown that in the deterministic setting, RC EDF can offer substantial performance gains over GPS. However, CAC procedures for EDF in the deterministic regime are considerably more complex than those for GPS, necessitating the use of approximation techniques [7] Frameworks based on ....

F. M. Chiussi and V. Sivaraman. Achieving high utilization in guaranteed services networks using early-deadline-first scheduling. In International Workshop on Quality of Service, pages 209--217, Napa, California, May 1998.

....the scope of this work. In this paper, we consider the case of an EDF scheduler in isolation (single node) the extension of our method to the multi node case is possible, using reshaping at each node (in a way inspired by the corresponding approach for deterministic end to end delay developed in [26,13,4]) and is the topic of a forthcoming publication. The rest of the paper is organized as follows. In Section 2, we provide a brief review of EDF scheduling and its CAC framework in the deterministic setting. In Section 3, after introducing the system model, we present the mathematical 3 framework ....

....sources, which match quite closely the values obtained from simulations. In this paper, we have focused on the single node in isolation; the extension to the multi node case, using traffic reshaping at each node (again inspired by the corresponding approach for deterministic end to end delays, see [26,13,4]) is the topic of a forthcoming publication. Such a statistical framework is potentially of great significance in the design of CAC schemes for networks which provide QoS in the form of statistical guarantees on data transfer delays, and can offer very substantial advantages in terms of network ....

F. M. Chiussi, V. Sivaraman, Achieving High Utilization in Guaranteed Services Networks using Early-Deadline-First Scheduling, In International Workshop on Quality of Service, pages 209--217, Napa, California, May 1998.

....scheduler delay bound at the m th switch for flow i. The maximum shaper delay is incurred only once, and is independent of the number of nodes on the path. Equation (2) in conjunction with the single node CAC derived from inequality (1) above readily leads to an end to end CAC framework [11] [4]: once an appropriate shaper E i has been chosen, the delay incurred in the shaper is computed; the remaining delay is split among the schedulers on the path of the flow, and the flow is admitted only if the single node CAC at each switch along the path admits the flow. The schedulable region ....

....performance for realistic traffic scenarios than both GPS and RC EDF disciplines that employ shapers chosen independent of flow hop lengths. V. CONCLUSIONS RC EDF has been proposed as a more efficient way of endto end delay provisioning in networks supporting deterministic QoS than GPS [11] [4]. The performance of RC EDF, however, depends crucially upon the choice of shaping parameters. In this paper, we have addressed the question of identifying traffic shapers that realize maximal RC EDF schedulable regions. We have shown that identifying the optimal shaper is in general infeasible, ....

F. M. Chiussi and V. Sivaraman. Achieving high utilization in guaranteed services networks using early-deadline-first scheduling. In International Workshop on Quality of Service, pages 209--217, Napa, California, May 1998.

....schemes. Call Admission Control (CAC) frameworks which employ these scheduling schemes to guarantee deterministic delay bounds to flows whose traffic is constrained according to a specified traffic envelope have been developed in literature (see [21] for a framework involving GPS and [14] [1] for a treatment of EDF) However, these deterministic frameworks, which provide hard guarantees on end to end delay, are excessively conservative in admitting flows into the network, since they have to account for the worst case scenarios that can be encountered in the switches, even though such ....

....node. We present numerical results in Section V. Finally, in Section VI, we offer concluding remarks and point to directions for future research. II. BACKGROUND A. EDF Scheduling We review some basic concepts related to EDF scheduling, and briefly describe the deterministic analysis of [14] [1] and the statistical framework of [22] The EDF scheduling discipline [10] 26] works as follows: each flow i at switch m is associated with a local delay bound d m i ; then, an incoming packet of flow i arriving to the scheduler at time t is stamped with a deadline t d m i , and packets in ....

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F. M. Chiussi and V. Sivaraman. Achieving high utilization in guaranteed services networks using early-deadline-first scheduling. In International Workshop on Quality of Service, pages 209--217, Napa, California, May 1998.

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F. M. Chiussi and V. Sivaraman, "Achieving high utilization in guaranteed services networks using early-deadline-first scheduling," Proc. IEEE IWQoS, 1998.

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