Fujun He 교수

Network function virtualization paradigm enables us to implement network functions provided in middleboxes as softwares that run on commodity servers. This paper proposes a backup resource allocation model for middleboxes with considering both failure probabilities of network functions and backup servers. A backup server can protect several functions; a function can have multiple backup servers. We take the importance of functions into account by defining a weighted unavailability for each funct

This article proposes a primary and backup resource allocation model that provides a probabilistic protection guarantee for virtual machines against multiple failures of physical machines in a cloud provider to minimize the required total capacity. A physical machine allocates both primary and backup computing resources for virtual machines. When any failure occurs, the survived physical machines with preplanned backup resources recover the virtual machines on the failed physical machines and ta

This paper proposes a backup resource allocation model that provides a probabilistic protection for primary physical machines in a cloud provider to minimize the required total capacity. When any random failure occurs, workloads are transferred to preplanned and dedicated backup physical machines for prompt recovery. In the proposed model, a probabilistic protection guarantee is introduced to prevent the cloud provider from capacity overbooking. We apply robust optimization in our model to formu

This paper proposes a backup resource allocation model for virtual networks with providing a probabilistic protection against multiple facility node failures by jointly considering backup computing and bandwidth resource allocation. Previous work only considers the backup computing resource allocation for virtual nodes regardless of the constraints from network aspects. In this paper, we firstly analyze the types of backup paths required for each virtual link in cases of multiple facility node f

Network function virtualization provides an efficient and flexible way to implement network functions deployed in middleboxes as software running on commodity servers. However, it brings challenges for network management, one of which is how to manage the unavailability of middleboxes. This article proposes an unavailability-aware backup allocation model with the shared protection to minimize the maximum unavailability among functions. The shared protection allows multiple functions to share the

This paper proposes a backup computing and transmission resource allocation model for virtual networks with providing a probabilistic protection against multiple facility node failures. The proposed model aims to find the allocation to minimize the required backup computing capacity, which guarantees the probability that the protection fails due to insufficient reserved backup computing capacity within a given value. The previous study only considers the backup computing resource allocation for

This paper proposes a survivable virtual network embedding model over elastic optical networks considering shared protection against any single substrate node or link failure. A virtual network request is embedded in the substrate network with allocating the primary and backup resources which are node-disjoint. Modulation selection and spectrum allocation with constraints from elastic optical networks are considered in the embedding procedure. We consider the backup computing and transmission re

This paper proposes a master and slave controller assignment model against multiple controller failures in software defined network with considering propagation latency between switches and controllers. In our model, a controller can be assigned to multiple switches, and the survivability of each switch is guaranteed to a certain degree by assigning multiple controllers to it. We define the average-case expected propagation latency, the worst-case expected propagation latency, and the expected n

Network function virtualization enables service providers to flexibly provision services with virtual network functions. Traffic uncertainty typically exists in a network, which can degrade the performance of a virtual network function. This paper proposes a robust virtual network function deployment model against the traffic uncertainty to minimize the total deployment cost with satisfying the service delay constraint. A virtual network function instance is allowed to be shared by different ser

This paper proposes a preventive priority setting model to handle load balancing against multiple controller failures in software defined networks. For each switch, a set of controllers can control it, where only one master controller controls the switch and others are slave controllers. We introduce a priority for each controller to become the master controller. At any time, the controller which does not fail and has the highest priority works as the master controller. Once the existing master

This paper proposes a main and secondary controller assignment model against multiple controller failures in software defined networks considering latency between switches and controllers. The survivability guarantee of each switch is satisfied by assigning a set of controllers, where one of them works as the main controller to control the switch. Given assigned controllers, we introduce a policy-based approach to automatically specify the main controllers in each failure pattern, which leads to

Network function virtualization paradigm enables us to implement network functions provided in middleboxes as software which runs on commodity servers. This paper proposes a backup resource allocation model for middleboxes with considering failure probabilities of network functions and backup servers. Multiple backup servers, each of which is allowed to protect several functions, can be assigned to protect one function. When a function fails, one of the corresponding servers providing protection

This paper proposes a preventive priority setting model to minimize the worst-case maximum utilization ratio against multiple controller failures in software defined networks. For a set of controllers able to manage a switch, we introduce a priority for each controller to become the main controller that controls the switch. Once the existing main controller fails, the survived controller which has the highest priority works as the main controller. This reassignment is automatically obtained acco

This paper proposes a survivable virtual network embedding model over elastic optical network with considering the shared protection against any single substrate node or link failure. We consider the backup computing and bandwidth resource sharing to reduce the required backup resources. A heuristic algorithm with polynomial time complexity is presented to solve the problem with considering promoting the backup resource sharing. The results observe that the rejection ratio is reduced about 60% i