Traditionally, research on routing and wavelength assignment over wavelength-routed WDM networks is concerned with immediate reservation (IR) demands. An IR demand typically does not specify a holding time for data transmission and the start time of the data transmission is assumed to be immediate (i.e. when the connection request arrives). The concept of advance reservation (AR) has recently been gaining attention for optical networks. An AR demand typically specifies information about the start of the data transmission or a deadline, as well as the holding time of the transmission. AR has several important applications for both wide-area networks and Grid networks. For example, AR can be used for adjusting virtual topologies to adapt to predictable peak hour traffic usage. It can be used to provide high-bandwidth services such as video conferencing and in Grid applications requiring the scheduled distribution of large files and for co-allocation of network and grid resources. AR can also be beneficial to the network by allowing the network operator to better plan resource usage and therefore increase utilization. Knowledge of the holding time can lead to more optimal decisions for resource allocation. This translates to better quality of service for users. In this paper we provide a comprehensive survey of the past and current work on advance reservation for optical networks. There have been many variations of the advance reservation concept proposed, so we will also provide a broad classification. In addition to the survey, we will discuss what we believe are important areas of future work and open challenges for advance reservation on optical networks.

A Survey of Advance Reservation Routing and Wavelength Assignment in Wavelength-Routed WDM Networks

In this paper, we propose a general scheduled traffic model, sliding scheduled traffic model. In this model, the setup time t/sub s/ of a demand whose holding time is T time units is not known in advance. Rather t/sub s/ is allowed to begin in a pre-specified time window [l,T] subject to the constraint that l/spl les/t/sub s//spl les/r-T. We then consider two problems: (1) how to properly place a demand within its associated time window to reduce overlapping in time among a set of demands; and (2) route and assign wavelengths (RWA) to a set of demands under the proposed sliding scheduled traffic model in mesh reconfigurable WDM optical networks without wavelength conversion. In addition, we consider how to rearrange a demand by negotiating a new setup time that minimizes the demand schedule change in case that the demand is blocked. To maximize temporal resource reuse, we propose a demand time conflict reduction algorithm to solve the first problem. Two algorithms, window based RWA algorithm and traffic matrix based RWA algorithm, are then proposed for the second problem. We compare the proposed RWA algorithms against a customized tabu search scheme. Simulation results show that the proposed demand time conflict reduction algorithm can resolve well over 50% of time conflicts and the space-time RWA algorithms are effective in satisfying demand requirements and minimizing total network resources used, d.

On service provisioning under a scheduled traffic model in reconfigurable WDM optical networks

In this paper, we investigate the static multicast advance reservation (MCAR) problem for all-optical wavelength-routed WDM networks. Under the advanced reservation traffic model, connection requests specify their start time to be some time in the future and also specify their holding times. We investigate the static MCAR problem where the set of advance reservation requests is known ahead of time. We prove the MCAR problem is NP-complete, formulate the problem mathematically as an integer linear program (ILP), and develop three efficient heuristics, seqRWA, ISH, and SA, to solve the problem for practical size networks. We also introduce a theoretical lower bound on the number of wavelengths required. To evaluate our heuristics, we first compare their performances to the ILP for small networks, and then simulate them over real-world, large-scale networks. We find the SA heuristic provides close to optimal results compared to the ILP for our smaller networks, and up to a 33% improvement over seqRWA and up to a 22% improvement over ISH on realistic networks. SA provides, on average, solutions 1.5-1.8 times the cost given by our conservative lower bound on large networks.

/pdf/static-routing-and-wavelength-assignment-for-multicast-9yaqt5zy3q.pdf

Static routing and wavelength assignment for multicast advance reservation in all-optical wavelength-routed WDM networks

Resource provisioning for survivable WDM networks under a sliding scheduled traffic model

We study the optimal survivability design problem under a scheduled traffic model in wavelength convertible WDM optical mesh networks. In this model, a set of demands is given, and the setup time and teardown time of a demand are known in advance. We formulate the joint routing and wavelength assignment problems into integer linear programs that maximally exploit network resource reuse in both space and time. To solve large problems, the joint RWA problems are divided to a routing subproblem and wavelength assignment subproblems which are then solved individually. The overall objective is to minimize the total number of wavelength-links used by working paths and protection paths of all traffic demands while 100% restorability is guaranteed against any single failures. Our simulation results indicate that the optimization of resource sharing in space and time enabled by our connection-holding-time-aware protection schemes can achieve significantly better resource utilization than schemes that are holding time unaware.

/pdf/on-optimal-survivability-design-in-wdm-optical-networks-3hi0xdtqea.pdf

On optimal survivability design in WDM optical networks under a scheduled traffic model

We study survivable service provisioning under a scheduled traffic model in wavelength convertible WDM optical mesh networks. In this model, a set of demands is given, and the setup time and teardown time of each demand are known in advance. We formulate the problem as integer linear programs that maximally exploit network resource reuse in both space and time. The objective is to minimize the total number of wavelength-links used by working paths and protection paths of all traffic demands while 100% restorability is guaranteed against any single failures. Our simulation results indicate that joint optimization of resource sharing in space and time enabled by our connection holding-time aware protection schemes can achieve significantly better resource utilization than schemes that are holding-time unaware

On survivable service provisioning in WDM optical networks under a scheduled traffic model

—In modern SD-WAN networks, a global controller continuously optimizes application and user intents by selecting the proper routing policies for each application. Nevertheless, the competition between ﬂows can still occur at each overlay link and it may degrade Quality of Service (QoS). To mitigate performance degradations in case of congestion, QoS policies can also be dynamically optimized to limit the rate of low-priority ﬂows and share the bandwidth among all ﬂows in a fair manner. This demonstration presents a comprehensive control plane architecture to coordinate path selection and rate allocation, in order to meet application requirements while optimizing a global objective (e.g., low congestion, best quality, and minimum cost).

Xinhui Zhang

Papers

On survivable service provisioning in WDM optical networks under a scheduled traffic model

Routing and QoS Policy Optimization in SD-WAN