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A number of schemes have been proposed for providing quality-of-service (QoS) differentiation in optical burst-switched (OBS) networks. Most existing schemes are based on a relative QoS model in which the service requirements for a given class of traffic are defined relative to the service requirements of another class of traffic. In this paper, we...
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... bursts labeled L0 can only use these wavelengths on the link . In the case that more than one class of traffic is guaranteed, the process is repeated until the necessary wavelengths have been reserved for all of the guaranteed traffic. The remaining unreserved wave- lengths are used to carry the best-effort traffic. For the scenario shown in Fig. 3(a), when a burst labeled L1 arrives at time , it can only be scheduled on Wavelength 3, which is statically pre- assigned to the bursts labeled ...
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... that group, the OBS node must keep track of the number of wavelengths currently occupied by bursts of each group. A burst with a given label can be dynam- ically scheduled onto an available wavelength if the number of wavelengths currently occupied by bursts of the same label is less than the number of wavelengths provisioned for that group. In Fig. 3(b), suppose the number of wavelengths that bursts la- beled L1 can use ...
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Citations
... Một hướng tiếp cận khác trong việc hạn chế tranh chấp tài nguyên, nâng cao được hiệu suất OBS là sử dụng phương pháp điều khiển chấp nhận lập lịch. Điều khiển chấp nhận lập lịch có thể được thực hiện tại nút biên hay nút lõi [3]. Trong đa số các mô hình điều khiển chấp nhận đã được đề xuất, các chùm ưu tiên thấp luôn bị đánh rơi nhiều hơn nhằm để dành tài nguyên cho các chùm ưu tiên cao nếu có tranh chấp xảy ra. ...
Vấn đề dự báo dựa trên quan sát phụ thuộc rất nhiều vào mật độ sự kiện đến và kích thước cửa sổ quan sát. Thực tế, nếu cửa sổ quan sát bé và mật độ sự kiện đến rời rạc thì độ chính xác dự báo sẽ thấp, nhưng nếu của sổ quan sát lớn và mật độ sự kiện đến dày đặc thì độ chính xác dự báo sẽ tăng đáng kể. Trong bài báo này, một khảo sát dựa trên mô phỏng sẽ được thực hiện với các kích thước cửa số quan sát khác nhau nhằm đánh giá hiệu quả của việc dự báo lưu lượng chùm đến phục vụ cho việc điều khiển chấp nhận lập lịch tại nút lõi OBS. Kết quả mô phỏng chỉ ra rằng, khi tải chùm đến cao và cửa sổ quan sát lớn thì kết quả dự báo sẽ chính xác hơn
... This kind of rigid guarantee is feasible in multimedia and mission-critical applications so that these applications would be supported in other constraints like less delay and more bandwidth. However, efficient resource provisioning and admission control mechanisms are required to support the QoS in the absolute mode [16]. ...
This paper concerns Quality of Service (QoS) provisioning in Optical Packet Switching (OPS) networks. We address the topic by proposing Dynamic Wavelength Grouping (DWG) for OPS, in this technique, available wavelengths are dynamically partitioned and allocated at each network link to particular classes of service. DWG adapts to traffic fluctuations by tracking the load status of every class of traffic and then schedules optical packets over group of wavelengths assigned for each class of service. Performance is examined using an own developed simulator. This simulator models various aspects of OPS in far detail. Two network topologies are studied under various parameter settings and traffic scenarios. DWG clearly outperforms its earlier static counterpart (SWG). It appears as flexible approach, efficiently functional even when the share of the high-priority load is temporarily low. Consequently, it minimizes the total blocking probability while preserving the desired service differentiation. We report also significant improvements in the network throughput.
... However, to overcome the said problem, it is possible to migrate current networks operation from a static to a dynamic operation [6]. The latter 20 is denoted as Dynamic Optical Networks, consisting in allocating the resources to a given user only when it requests communication. Although it is already possible to deploy this type of technology, this has not happened yet because it is unclear how much network capacity savings can be expected compared to the necessary investments [7]. ...
... This situation has been taking care off on a different context. For example, in the OBS context, diverse 100 schemes have been presented concerning the quality of services, such as Wavelength Grouping and Intentional Dropping, among others [18,19,20]. However, this situation has not been studied in the current optical networks with wavelength continuity constraints. ...
This article gives an insight on the importance to assign a different capacity to each network link and to tighten the Quality of Service (QoS) provision in the network, in dynamic WDM Optical Networks with wavelength continuity constraints. In the text, several examples illustrate the performance of different strategies.
The usual procedure to compute the number of wavelengths of each network link consists of choosing the same capacity to each link on the network. This decision is selected, in most cases, by simplicity and simulation limitations. Notwithstanding, there are no technical motives to force a uniform capacity on the network. In consequence, we analyze the impact on the network capacity of designating the minimum amount of wavelengths to each network link, while satisfying each user QoS requirement.
Moreover, despite the chosen dimensioning strategy, it is usual to offer a much better QoS than requested for some users, with the corresponding waste of resources. We can amend this issue by limiting which wavelengths are available to each user according to its particular QoS constraint. This technique, known as Wavelength Grouping, seeks to provide to each user a QoS level closer to the one defined in the Service Level Agreement. By doing so, it is possible to reduce the network capacity needed to allow communication to its user, or diminishing the network blocking probability for a given wavelength capacity.
In spite of the usual approach, in this work, we demonstrate that a non-uniform dimensioning strategy and a tighten QoS provision allows to save significant networks capacity, while simultaneously provisioning to each user the QoS established in its Service Level Agreement. This fact is very relevant nowadays, where an impending capacity crunch in optical networks is an important issue.
... In the occurrence of the multi-class traffic, 2 types of "QoS differentiation schemes" are stated namely, "absolute QoS differentiation [6]" and "relative QoS differentiation [7]". In crucial implementations, the "absolute QoS provisioning" is obtained by allocating the resources of wavelength approximately in the network links [8]. ...
The optical burst switching is promising optical network technique that intends to transmit data in the form of bursts with the ability of dynamic switching between sub-wave lengths. One among the crucial issues of the OBS networks is burst loss due to suboptimal and often impediment burst scheduling and wavelength allocation strategies. Hence, the major contributions of the contemporary research in regard to OBS networks entails to portray the optimal burst routing strategies. The contribution of this manuscript is balanced wavelength allocation using differential evolution method in short referred as BWADE, which selects an optimum multi-hop route that intends to uses multi-objective QoS aspects as a fitness scale for differential evolution algorithm. The experimental study concluding that the proposed BWADE outperforming the other contemporary routing approaches through simulation outcomes.
... In other words, the admission control is necessary to conserve more resources for HP bursts, while it limits resources to LP bursts. There are several proposed admission control models, including SWG (Static Wavelength Grouping), DWG (Dynamic Wavelength Grouping) [3] and LLAC (Load-Level Admission Control) [4]. However, these models assume that the traffic of arriving bursts is stable, the admission control is then performed based on the amount of allocated wavelengths and the idle state of these wavelengths. ...
... The first proposals for the service differentiation supporting admission control are SWG and DWG [3]. Two classes of HP and LP are considered and the admission control is based on the number of wavelengths occupied by each priority class. ...
Scheduling is an operation that has a significant impact on the data forwarding performance of OBS nodes. In the case of service differentiation, the scheduling operation is also subject to additional controls from service differentiation supporting mechanisms in which an arriving burst can be admitted to be scheduled depending on its priority level and the availability of wavelengths. There are several proposed scheduling admission control models, but it is hypothesized that the traffic of arriving bursts is stable, the admission control is then performed, based on the amount of allocated wavelengths and the idle state of these wavelengths. However, arriving burst traffics in OBS networks usually fluctuate and accurate traffic forecasting will help allocate wavelengths more efficiently, increasing the scheduling efficiency in term of increasing bandwidth utilization and reducing burst loss. This paper proposes a model of traffic prediction based admission control, which includes a statistical method of forecasting the arriving burst rate for flexible wavelength allocation and a mechanism of prioritizing more resources for high-priority bursts. The simulation results have proved the efficiency of the proposed model in terms of the burst loss and the bandwidth utilization. A Markov chain based analysis model is also introduced to validate the proposed model.
... Hiện nay có các giải thuật lập lịch có xét đến chất lượng dịch vụ đã được đề xuất gồm: G-LAUC-VF (Generalized LAUC-VF) [6], LA-FFVF (Latest Available and First Fit Unused Channel with Void Filling) [7], SWG (Static Wavelength Grouping) [2], DWG (Dynamic Wavelength Grouping) [3] và LLAC (Load-Level Admission Control) [4]. Với giải thuật LA-FFVF sử dụng các giải thuật lập lịch trực tiếp LAUC để lập lịch cho các chùm ưu tiên cao và sử dụng giải thuật FFUC-VF để lập lịch cho các chùm ưu tiên thấp nhằm giảm độ phức tạp giải thuật và tận dụng các khoảng trống được tạo ra trên các kênh để lập lịch cho các chùm đến. ...
Tóm tắt: Mạng chuyển mạch chùm quang được xem như công nghệ đáp ứng được nhu cầu băng thông và đảm bảo chất lượng dịch vụ cho mạng Internet toàn quang của thế hệ tiếp theo. Tuy nhiên do thiếu bộ đệm quang tại các nút chuyển mạch lõi vì vậy việc đảm bảo chất lượng lượng dịch vụ cho các dịch vụ khác nhau trong mạng chuyển mạch chùm quang khó khăn hơn so với mạng điện tử truyền thống. Hiện nay đã có một số giải thuật lập lịch đã được công bố nhằm giải quyết được vấn đề này, tuy nhiên các giải thuật lập lịch thực hiện đảm bảo chất lượng dịch vụ cho các chùm ưu tiên và không ưu tiên thông qua việc thiết lập cố định các kênh bước sóng ra mà không xem xét tải lưu lượng đến của các lớp dịch vụ. Trong nghiên cứu này chúng tôi đề xuất một giải thuật lập lịch với phương pháp dự đoán dựa trên tải lưu lượng đến của các chùm để phân bổ tài nguyên bước sóng hợp lý cho các lớp ưu tiên trong mạng OBS. Các phân tích và đánh giá hiệu quả của giải thuật lập lịch dựa trên mô phỏng sẽ khẳng định ưu điểm của mô hình được đề xuất này. Từ khóa: Mạng OBS, giải thuật lập lịch, phân biệt dịch vụ, phân bổ tài nguyên, dự đoán tải lưu lượng. 1. GIỚI THIỆU Tốc độ phát triển nhanh của Internet trong những năm gần đây, cùng với sự bùng nổ của các loại hình dịch vụ truyền thông, đã làm gia tăng không ngừng nhu cầu về băng thông truyền thông. Điều này đã đặt ra một thách thức mới trong việc tìm kiếm công nghệ truyền thông phù hợp nhằm nâng cao khả năng vận chuyển của mạng thế hệ mới. Mạng sợi quang cùng với sự phát triển của công nghệ ghép kênh bước sóng (Wavelength Division Multiplexing), đã mang đến một giải pháp hoàn hảo đáp ứng được nhu cầu băng thông bùng nổ của Internet trong tương lai. Từ khi xuất hiện vào thập niên 90, mạng sợi quang đã trải qua nhiều thế hệ phát triển [1]: từ những mô hình định tuyến bước sóng (Wavelength-Routed) ban đầu dựa trên những đường quang (lightpath) đầu cuối dành riêng, cho đến các mô hình chuyển mạch gói quang (Optical Packet Switching) được đề xuất gần đây, với ý tưởng xuất phát từ các mô hình mạng chuyển mạch gói điện tử. Tuy nhiên với một số hạn chế về công nghệ, như chưa thể sản xuất các bộ đệm quang (tương tự bộ nhớ RAM trong môi trường điện tử) hay các chuyển mạch ở tốc độ nano giây [1] mô hình chuyển mạch gói quang chưa thể trở thành hiện
... In the event of multiclass traffic, two types of QoS differentiation schemes are reported, namely, relative QoS differentiation [6] and absolute QoS differentiation [7]. In time critical applications, absolute QoS provisioning is achieved by appropriately allocating the wavelength resources in network links [8]. ...
The issue of burst losses imposes a constraint on the development of optical burst switching (OBS) networks. Heavy burst losses drastically affect the quality of service (QoS) intended by the end users. This article presents a QoS aware routing and wavelength allocation (RWA) technique for burst switching in OBS networks. The RWA problem is modeled as a bi-objective integer linear programming (ILP) problem where the objective functions are based on minimizing both the number of wavelengths used, and the number of hops traversed to fulfill the burst transmission requests for a given set of node pairs. The ILP model is solved by a novel approach based on a differential evolution (DE) algorithm. Analytical results show that DE algorithm provides a better performance when compared against shortest path (SP) routing, a widely accepted routing strategy for OBS networks. Index Terms: burst loss; optical burst switching; quality of service; routing and wavelength assignment; integer linear programming; differential evolution.
... Extending our previous work on MPTCP over OBS in datacenters [3], and QoS provision scheme QAMO, allows us to create a network model and QoS provisioning scheme for software defined datacenters called QAMO-SDN. There is rich research on QoS schemes in optical burst switching for wide area networks [17][18][19]. OBS has been considered as the best compromise between optical circuit switching (OCS)and optical packet switching (OPS) due to its granularity and bandwidth flexibility, and would be suitable for data centers eventually as optical switching technology gets mature [20]. TCP is the most dominant transport layer protocol in internet and TCP over OBS has been extensively studied [21][22][23]. ...
... Extending our previous work on MPTCP over OBS in datacenters [3], and QoS provision scheme QAMO, allows us to create a network model and QoS provisioning scheme for software defined datacenters called QAMO-SDN. There is rich research on QoS schemes in optical burst switching for wide area networks [17][18][19]. OBS has been considered as the best compromise between optical circuit switching (OCS)and optical packet switching (OPS) due to its granularity and bandwidth flexibility, and would be suitable for data centers eventually as optical switching technology gets mature [20]. TCP is the most dominant transport layer protocol in internet and TCP over OBS has been extensively studied [21][22][23]. ...
Cloud based datacenters will be most suitable candidates for future software defined networking. The QoS requirements for shared data centers, hosting diverse applications could be successfully achieved through SDN architecture. This paper provides an extension of our previously proposed scheme QAMO that was aimed at achieving tangible QoS in datacenters through controlling bandwidth reservation in Multipath TCP and OBS layer while maintaining throughput efficiency. However, QAMO was designed for traditional networks and did not have the capability to adapt to current network status as expected from future software defined networks. The paper presents an enhanced algorithm called QAMO-SDN that introduces a controller layer in previously proposed architecture and achieves adaptive QoS differentiation based on current network feedback. QAMO-SDN inherits the architecture of QAMO, using Multipath TCP over OBS networks. We evaluate the performance of QAMO-SDN under different network loads and topologies using realistic data center traffic models and present the results of our detailed simulation tests.
... In the context of multi-class traffic, the loss probability of a given class can be reduced by giving privilege to this class over others when contention occurs. In the literature, two kinds of QoS differentiation schemes for OBS networks have been reported, namely, relative QoS differentiation [23], [24] and absolute QoS differentiation [25], [26]. Although most of the QoS mechanisms proposed for OBS networks offer relative QoS guarantees only, still absolute QoS guarantees are required by critical applications. ...
Optical Burst Switching (OBS) is considered as an efficient switching paradigm for building the next generation optical Internet. This review has been motivated by the need for techniques that are capable of supporting the future bandwidth requirement of next-generation applications and services of Internet Protocol (IP) networks. The authors have discussed the basic concepts of OBS paradigm and outlined the signaling and scheduling issues related to OBS networks. Further, a brief summary on the issues that are essential for provisioning Quality-of-Service (QoS) in OBS networks has been outlined. Finally, an analytical model is presented to provide Burst Loss Probability (BLP) guarantees between every pair of source-destination nodes in the network.
