Enabling multicast slices in edge networks

Telecommunication networks are undergoing a disruptive transition towards distributed mobile edge networks with virtualized network functions (VNFs) (e.g., firewalls, Intrusion Detection Systems (IDSs), and transcoders) within the proximity of users. This transition will enable network services, especially IoT applications, to be provisioned as network slices with sequences of VNFs, in order to guarantee the performance and security of their continuous data and control flows. In this paper we study the problems of delay-aware network slicing for multicasting traffic of IoT applications in edge networks. We first propose exact solutions by formulating the problems into Integer Linear Programs (ILPs). We further devise an approximation algorithm with an approximation ratio for the problem of delay-aware network slicing for a single multicast slice, with the objective to minimize the implementation cost of the network slice subject to its delay requirement constraint. Given multiple multicast slicing requests, we also propose an efficient heuristic that admits as many user requests as possible, through exploring the impact of a non-trivial interplay of the total computing resource demand and delay requirements. We then investigate the problem of delay-oriented network slicing with given levels of delay guarantees, considering that different types of IoT applications have different levels of delay requirements, for which we propose an efficient heuristic based on Reinforcement Learning (RL). We finally evaluate the performance of the proposed algorithms through both simulations and implementations in a real test-bed. Experimental results demonstrate that the proposed algorithms is promising

Efficient NFV-Enabled Multicasting in SDNs

IEEE Multicasting is a fundamental functionality of many network applications, including online conferencing, event monitoring, video streaming, and so on. To ensure reliable, secure and scalable multicasting, a service chain that consists of network functions (e.g., firewalls, Intrusion Detection Systems (IDSs), and transcoders) usually is associated with each multicast request. We refer to such a multicast request with service chain requirement as an NFV-enabled multicast request. In this paper, we study NFV-enabled multicasting in a Software- Defined Network (SDN) with an aim to maximize network throughput while minimizing the implementation cost of admitted NFV-enabled multicast requests, subject to network resource capacity, where the implementation cost of a request consists of its computing resource consumption cost in servers and its network bandwidth consumption cost when routing and processing its data packets in the network. To this end, we first formulate two NFV-enabled multicasting problems with and without resource capacity constraints and one online NFV-enabled multicasting problem.We then devise two approximation algorithms with an approximation ratio of 2M for the NFV-enabled multicasting problems with and without resource capacity constraints, if the number of servers for implementing the service chain of each request is no greater than a constant M (≥1). We also study dynamic admissions of NFV-enabled multicast requests without the knowledge of future request arrivals with the objective to maximize the network throughput, for which we propose an efficient heuristic, and for a special case of dynamic request admissions, we devise an online algorithm with a competitive ratio of O(log n) for it when M = 1, where n is the number of nodes in the network. We finally evaluate the performance of the proposed algorithms through experimental simulations. Experimental results demonstrate that the proposed algorithms are promising and outperform existing heuristics

Efficient Resource Allocation for Throughput Maximization in Next-Generation Networks

Software-Defined Networking (SDN) and Network Function Virtualization (NFV) have emerged as the foundation of the next-generation network architecture by introducing great flexibility and network automation capabilities, including automatic response to faults and load changes and programmatic provision of network resources and connections. It has been envisioned that the SDN- and NFV-based next-generation network architecture will play a critical role in providing network services to users, where the desired network services, including data transfer and policy enforcement, are fulfilled by allocating network resources using virtualization technologies. However, the disparity between ever-growing user demands and scarce network resources makes resource allocation exceptionally central to the performance of a network service, because only by effectively allocating these scarce resources can a network service provider satisfy users and maximize the gain from running the service. In this thesis, we study efficient resource allocation for network throughput maximization in next-generation networks, while meeting user resource demands and Quality of Service (QoS) requirements, subject to network resource capacities. This however poses great challenges, namely, (1) how to maximize network throughput, considering that both SDN-enabled switches and links are capacitated, (2) how to maximize the network throughput while taking into account network function and QoS requirements of users, (3) how to dynamically scale and readjust resource allocation for user requests, and (4) how to provision a network service that can satisfy user reliability requirements. To address these challenges, we provide a thorough study of network throughput maximization problems in the context of the next-generation network architecture, by formulating the problems as optimizations problems and developing novel optimization frameworks and algorithms for the problems. Specifically, this thesis makes the following contributions. Firstly, we consider dynamic user request admissions where user requests arrive one by one and the knowledge of future request arrivals is not given as a priori. We develop a novel cost model that accurately captures the usage costs of network resources and propose online algorithms with provable performance guarantees. Secondly, we study the problem of realizing user requests with network function requirements, with the objective of maximizing network throughput, while meeting user QoS requirements, subject to resource capacity constraints. For this problem, we develop two algorithms that strive for the trade-off between the accuracy/quality of a solution and the running time of obtaining the solution. Thirdly, we investigate maximization of network throughput by dynamically scaling network resources while minimizing the overall operational cost of a network. We propose a unified framework for two types of resource scaling {--} vertical scaling and horizontal scaling. Through non-trivial reductions of the problem of concern into several classic problems, we propose an algorithm that has been empirically demonstrated to deliver near-optimal solutions. Fourthly, we deal with the problem of reliability-aware provisioning of network resources for users, with the aim of maximizing network throughput. We devise an approximation algorithm with a logarithmic approximation ratio for the general case of this problem. We also develop constant-factor approximation and exact algorithm for two special cases of the problem, respectively. The formulated problem is a generalization of several classic optimization problems. Finally, in addition to extensive theoretical analyses, we also evaluate the performance of proposed algorithms empirically through experimental simulations based on real and synthetic datasets. Experimental results show that the proposed algorithms significantly outperform existing algorithms

Efficient Virtualized Network Service Provisioning in Mobile Edge Computing

There is a substantial growth in the usage of mobile devices. These devices, including smartphones, sensors, and wearables, are limited by their computational and energy capacities, due to their portable size. Mobile edge computing (MEC), which provides cloud resources at the edge of mobile network in close proximity to mobile users, is a promising technology to reduce response delays, ensure network operation efficiency, and improve user service satisfaction. Mobile edge computing is a promising technology to leverage the capability of mobile devices to offload tasks to nearby edge-clouds (cloudlets) for processing. Furthermore, Network Function Virtualization (NFV) is another promising technique that implements various network functions for many applications as pieces of software in servers or cloudlets in MEC networks. The provisioning of virtualized network services in MEC can improve user service experiences, simplify network service deployment, and ease network resource management. In this thesis, we will focus on the efficient virtualized network service provisioning in MEC networks by judicious resource allocations and request admissions to maximize network throughput and minimize request admission cost in different application scenarios. We firstly address dynamic request admissions with service function chain requirements in MEC with the objective to maximize the profit collected by the network service provider, assuming that the cloudlets are located at different geographical locations and electricity prices at different locations are different. We formulate an integer linear programming (ILP) solution to the offline problem, and devise an online algorithm with a provable competitive ratio for the online problem when requests arrive one by one without the knowledge of future request arrivals. We then study NFV-enabled multicasting that is a fundamental routing problem in an MEC network, subject to resource capacities on both its cloudlets and links. We devise an admission framework for single NFV-enabled multicast request admission with the aim to minimize request admission cost. We then develop an efficient algorithm for the throughput maximization problem for the admissions of a given set of NFV-enabled multicast requests. We also devise an online algorithm with a provable competitive ratio for the online NFV-enabled multicast request admissions. We thirdly investigate virtualized network function service provisioning for mobile users in MEC that takes into account user mobility and service delay requirements. We formulate two novel optimization problems of user service request admissions with the aims to maximize the accumulative network utility and accumulative network throughput for a given time horizon, respectively, where network utility is a submodular function that can be used to tradeoff between individual user service satisfaction and accumulative network throughput. We then devise a constant approximation algorithm for the utility maximization problem. We also develop an online algorithm for the accumulative throughput maximization problem. We fourthly explore a non-trivial tradeoff between different types of resources in NFV-enabled request scheduling in MEC with an objective to minimize request admission cost, through introducing a novel concept - load factor. We formulate the cost minimization problem that admits all requests by assuming that there is sufficient computing resource in MEC to accommodate the requested VNF instances of all requests, for which we formulate an ILP solution and two efficient heuristic algorithms. We also deal with the problem under the computing resource constraint, for which we formulate an ILP solution when the problem size is small; otherwise, we devise efficient algorithms for it. We finally summarize the thesis and explore several potential research topics that are based on the work in this thesis

An End-to-End Performance Analysis for Service Chaining in a Virtualized Network

Future mobile networks supporting Internet of Things are expected to provide both high throughput and low latency to user-specific services. One way to overcome this challenge is to adopt Network Function Virtualization (NFV) and Multi-access Edge Computing (MEC). Besides latency constraints, these services may have strict function chaining requirements. The distribution of network functions over different hosts and more flexible routing caused by service function chaining raise new challenges for end-to-end performance analysis. In this paper, as a first step, we analyze an end-to-end communications system that consists of both MEC servers and a server at the core network hosting different types of virtual network functions. We develop a queueing model for the performance analysis of the system consisting of both processing and transmission flows. We propose a method in order to derive analytical expressions of the performance metrics of interest. Then, we show how to apply the similar method to an extended larger system and derive a stochastic model for such systems. We observe that the simulation and analytical results coincide. By evaluating the system under different scenarios, we provide insights for the decision making on traffic flow control and its impact on critical performance metrics.Comment: 30 pages. arXiv admin note: substantial text overlap with arXiv:1811.0233

On the Orchestration and Provisioning of NFV-enabled Multicast Services

The paradigm of network function virtualization (NFV) with the support of software-defined networking has emerged as a prominent approach to foster innovation in the networking field and reduce the complexity involved in managing modern-day conventional networks. Before NFV, functions, which can manipulate the packet header and context of traffic flow, used to be implemented at fixed locations in the network substrate inside proprietary physical devices (called middlewares). With NFV, such functions are softwarized and virtualized. As such, they can be deployed in commodity servers as demanded. Hence, the provisioning of a network service becomes more agile and abstract, thereby giving rise to the next-generation service-customized networks which have the potential to meet new demands and use cases. In this thesis, we focus on three complementary research problems essential to the orchestration and provisioning of NFV-enabled multicast network services. An NFV-enabled multicast service connects a source with a set of destinations. It specifies a set of NFs that should be executed at the chosen routes from the source to the destinations, with some resources and ordering relationships that should be satisfied in wired core networks. In Problem I, we investigate a static joint traffic routing and virtual NF placement framework for accommodating multicast services over the network substrate. We develop optimal formulations and efficient heuristic algorithms that jointly handle the static embedding of one or multiple service requests over the network substrate with single-path and multipath routing. In Problem II, we study the online orchestration of NFV-enabled network services. We consider both unicast and multicast NFV-enabled services with mandatory and best-effort NF types. Mandatory NFs are strictly necessary for the correctness of a network service, whereas best-effort NFs are preferable yet not necessary. Correspondingly, we propose a primal-dual based online approximation algorithm that allocates both processing and transmission resources to maximize a profit function that is proportional to the throughput. The online algorithm resembles a joint admission mechanism and an online composition, routing, and NF placement framework. In the core network, traffic patterns exhibit time-varying characteristics that can be cumbersome to model. Therefore, in Problem III, we develop a dynamic provisioning approach to allocate processing and transmission resources based on the traffic pattern of the embedded network service using deep reinforcement learning (RL). Notably, we devise a model-assisted exploration procedure to improve the efficiency and consistency of the deep RL algorithm