Deterministic Service Function Chaining over Beyond 5G Edge Fabric

Service function chaining (SFC), based on the network function virtualization (NFV) technology, is a promising candidate for realizing agile and elastic network service provisioning. This paper tackles a SFC deployment across multiple domains where only abstracted intra-domain resource information is available. For the multi-domain SFC deployment, a privacy preserving deployment mechanism called PPDM has been proposed. To conceal privacy of domains, PPDM abstracts intradomain resource information to a binary matrix, and adopts deep reinforcement learning (DRL) for flexible SFC deployment. However, because PPDM deploys all Virtual Network Functions (VNFs) included in a single SFC in a batch manner, substrate nodes need to redundantly reserve the resources required by the deployable VNFs until the construction of the SFC is completed. As a result, the deployment of the SFC may fail because of the lack of the resources on substrate nodes. In this paper, to improve acceptance ratio of SFC requests, we propose a privacy-preserving sequential deployment mechanism (PPSDM) for SFC deployment across multiple domains. The key idea behind PPSDM is to deploy VNFs in a single SFC one by one in a sequential manner to avoid redundant reservation of resources. Comprehensive simulations demonstrate that PPSDM achieves up to 22% higher acceptance ratio of SFC requests compared to the baseline approaches such as PPDM.

To reduce the processing delay from the sequentially running virtual network functions (VNFs) in a service function chain (SFC), network function parallelism (NFP) is introduced that allows VNFs of the SFC to run in parallel. Existing NFP solutions only focused on improving parallelism benefits without paying much attention to resource utilization while deploying VNFs of SFCs. We take advantage of resource-delay dependency to propose a flexible and efficient parallelized SFC placement mechanism called FlexSFC which determines the optimal SFC placement while reducing resource usage and meeting end-to-end delay guarantees of the SFCs deployed. Initial results show that FlexSFC guarantees the end-to-end delay requirement with better resource utilization and SFC acceptance rate than the state-of-the-art approaches.

Owing to the Network Function Virtualization (NFV) and Software-Defined Networks (SDN), Service Function Chain (SFC) has become a popular service in SDN and NFV-enabled network. However, as the Virtual Network Function (VNF) of each type is generally multi-instance and flows with SFC requests must traverse a series of specified VNFs in predefined orders, it is a challenge for dynamic SFC formation to optimally select VNF instances and construct paths. Moreover, the load balancing and end-to-end delay need to be paid attention to, when routing flows with SFC requests. Additionally, fine-grained scheduling for traffic at flow level needs differentiated routing which should take flow features into consideration. Unfortunately, traditional algorithms cannot fulfill all these requirements. In this paper, we study the Differentiated Routing Problem considering SFC (DRP-SFC) in SDN and NFV-enabled network. We formulate the DRP-SFC as a Binary Integer Programming (BIP) model aiming to minimize the resource consumption costs of flows with SFC requests. Then a novel routing algorithm, Resource Aware Routing Algorithm (RA-RA), is proposed to solve the DRP-SFC. Performance evaluation shows that RA-RA can efficiently solve the DRP-SFC and surpass the performance of other existing algorithms in acceptance rate, throughput, hop count and load balancing.

The increasing demand in Mobile Edge Computing (MEC) networks has led to the emergence of Network Function Virtualization (NFV) technology. Through the virtualization technique, NFV can decouple each Virtual Network Function (VNF) from the hardware and deploy it flexibly in the MEC. Each service request in NFV assembles a Service Function Chain (SFC) by tying different VNFs and processes the traffic in the chained order. How to allocate resources and deploy SFC in MEC to meet Quality of Service (QoS) requirements is an important challenge for NFV. An increase in the number of VNFs with traffic passing one after the other causes high delay in SFC assembly. Also, the demanded resources may change during SFC assembly, which is clearly neglected in existing works. Therefore, high delay and resource demand uncertainty during SFC assembly affect QoS. With this motivation, we solve the SFC deployment problem by Parallelizing VNFs under Resource Demand Uncertainty (PVRDU) in MEC. We use the dependency between VNFs to transform the original SFC into a parallel SFC and then assemble several sub-SFCs based on a Deep Reinforcement Learning (DRL) approach. Meanwhile, PVRDU uses a Markov-based approximation algorithm to handle resource demand uncertainty. We perform extensive trace-driven simulations to verify the effectiveness of the proposed algorithm. The evaluation results of PVRDU are promising in different aspects compared to state-of-the-art methods. Specifically, for the considered scenario, DPC reduced SFC delay by as much as 8.7%.

Service Function Chaining (SFC) can be a basic deployment unit that composes a chaining order of required network functions to provide a network service. With the proliferation of Software-Defined Networking (SDN) and cloud computing, such virtualized network functions can be dynamically deployed in different sites, depending on SFC requests. While offering the advantages of flexibility and efficiency, this also leaves management complexity and room for optimization where Machine Learning (ML) can be applicable to solve the problems based on monitoring data. In this paper, we treat SFC as a problem of finding a best source-to-destination routing path from multiple candidates with different link costs and a required traversal order of network functions. There are many mathematical approaches that ensure best optimum but not scalable to the problem size, whereas our approach hides underlying considerations by applying ML technique on measured SFC data to quickly find suboptimal routing paths on a new SFC request, based on their predicted network performance such as the number of successful requests or end-to-end delay. So, we developed a measurement system that records the performance and path costs of SFCs in emulated networks with different per link costs and chain lengths. Then, we evaluate four different ML models for the approach described above.

Hop-by-hop bandwidth allocation and deployment for SFC with end-to-end delay QoS guarantees

Service Function Chaining (SFC) serves the traffic of a specific service along an ordered set of Service Functions (SFs). SFC uses Software Defined Networking (SDN) and Network Function Virtualization (NFV) technologies to reach the deployment and removal of SFC in an appropriate time with minimal costs. However, during the life time of deployed SFCs, the SFs are exposed to the risk of overloading, which results in an end-to-end packets drop and high delay at the application level. This paper presents the concept of a Scalable SFC Orchestrator capable of deploying SF Chains following the ETSI NFV architectural model, as well as orchestrating the runtime phase by rerouting the traffic to a different path in case of overload of certain SF instances. Moreover, a selection algorithm is presented to build the updated paths after scaling. The Scalable Orchestration feature is implemented and added as a main feature to an SFC Orchestrator. Furthermore, it is integrated into a current NFV architecture and evaluated in an NFV environment making use of the Fraunhofer FOKUS Open Baton toolkit in an OpenStack and Open Daylight based environment.

A comprehensive survey of service function chain provisioning approaches in SDN and NFV architecture

In order to achieve reliability, security, and scalability, the request flow in the Internet of Things (IoT) needs to pass through the service function chain (SFC), which is composed of series-ordered virtual network functions (VNFs), then reach the destination application in multiaccess edge computing (MEC) for processing. Since there are usually multiple identical VNF instances in the network and the network environment of IoT changes dynamically, placing the SFC for the IoT request flow is a significant challenge. This paper decomposes the dynamic SFC placement problem of the IoT-MEC network into two subproblems: VNF placement and path determination of routing. We first formulate these two subproblems as Markov decision processes. We then propose a meta reinforcement learning and fuzzy logic-based dynamic SFC placement approach (MRLF-SFCP). The MRLF-SFCP contains an inner model that focuses on making SFC placement decisions and an outer model that focuses on learning the initial parameters considering the dynamic IoT-MEC environment. Specifically, the approach uses fuzzy logic to pre-evaluate the link status information of the network by jointly considering available bandwidth, delay, and packet loss rate, which is helpful for model training and convergence. In comparison to existing algorithms, simulation results demonstrate that the MRLF-SFCP algorithm exhibits superior performance in terms of traffic acceptance rate, throughput, and the average reward.

Network Function Virtualization (NFV) has become a promising technology, which is used to replace the complex hardware implementation of various Network Functions. Virtual Network Functions (VNFs) are placed on the servers to realize these functions of a network, for example 5G network. Such an implementation reduces the expenditure and latency significantly. However, it also comes with its own set of challenges. One of the prominent challenges of NFV is the placement problem. The requests are in the form of a Service Function Chain (SFC), which is a pre-defined sequence of VNFs. When an SFC request comes in, resources must be allocated to the VNF instances to satisfy the requirements. In this paper, we propose an effective algorithm D3T (Double Deep Q-Network Decision Transformer) to optimize the SFC placement. The algorithm is designed using a Decision Transformer (DT) that is assisted by a Double Deep Q-Network (DDQN). We employ a DDQN model as the baseline algorithm to generate offline training data. The trajectory data in the Experience Reply Memory of DDQN will be processed into sequences and modeled by a transformer. The algorithm’s objective function considers end-to-end delay and rejection ratio as the objectives. Specifically, D3T combines the transformer with DRL to give an optimal solution. The results presented demonstrate the effectiveness of the proposed solution.

Network function virtualization (NFV) is able to reduce the delay and improve the flexibility of network services in mobile edge computing (MEC) networks via deploying the service function chain (SFC) that consists of a sequence of ordered virtual network functions. However, it is still challenging to deploy SFC with delay guarantees and resource efficiency while taking into account the real-time network variations and dispersed edge server nodes in NFV/MEC-enabled networks. To address the issue, this paper proposes a self-attention mechanism-based double deep Q-network algorithm (SA-DDQN) for SFC deployment to jointly minimize the resource consumption on servers and bandwidth consumption on links within delay limits in dynamic NFV/MEC-enabled networks. In particular, we introduce the self-attention mechanism in the deep neural network structure, which enables the agent to pay its attention on more valuable physical nodes when making decisions, thus improving the efficiency of SFC deployment. Additionally, we utilize the Markov decision process (MDP) model to solve the problem of real-time network state variations. Finally, extensive simulation results show that our proposed SA-DDQN SFC deployment algorithm can reduce resource consumption by 25% and delay by 18.4% compared with the state-of-the-art algorithm.

To meet the increasing traffic demands characterized by large bandwidth and high burstiness, more traffic has been moving to inter-datacenter elastic optical networks (inter-DC EONs) for processing. The integration of two emerging paradigms, network function virtualization (NFV) and software-defined networking (SDN), enables Internet service providers (ISPs) to deploy service function chains (SFCs) from users flexibly while reducing operational and capital expenditures. This article focuses on the problem of online SFC provisioning in inter-DC-EONs with the aim of maximizing ISP profits, where the challenge in jointly allocating IT and spectrum resources when deploying SFCs is balanced with the deployment costs of processing as many user requests as possible. We design two-phase time-efficient orchestration algorithms for online SFC requests and the strategy of SFC splitting is adopted to improve the utilization of spectrum resources on fiber links. Simulation results show that, compared with the existing algorithm, our proposed algorithms significantly shorten the deployment time, improve total profit of ISP by up to 40% and reduce the blocking probability by up to 35%.

Network Function Virtualization (NFV) technology facilitates flexible and fast service provisioning by deploying network functions in wished positions and chaining order as Service Function Chain (SFC). Empirically, if the processing inside some Virtual Network Functions (VNFs) does not relate to each other, parallel chaining them can further improve the performance, such as reducing the end-to-end hops of SFCs. However, it is often ignored that parallel deploy VNFs will also introduce additional VNFs to replicate, distribute, and merge data. This will add hops and increase resource consumption. Will parallel deployment of VNFs in SFCs necessarily bring benefits? Regarding multiple parallel forms of an SFC, which one is the best? Further, how does the service process of the NFV network affect the parallel decisions of VNFs? In this paper, we design an NFV orchestrator, DP-NFVO, to maximize the revenue of NFV Service Providers and provide quantitative insights into the impact of parallel VNFs deploy-ment. Precisely, we first refine existing VNF parallelism rules and discuss the impact of VNF parallelism on latency and resource consumption, and analyze the optimal form of parallelism for SFCs. Second, we decompose the service request process in NFV networks into multiple stages and provide a joint model of VNF parallelism and deployment. Further, we design a VNF online deployment and parallelism decision policy for DP-NFVO based on Proximal Policy Optimization (PPO) to maximize revenue. Finally, we demonstrate the effectiveness and adaptability of DP-NFVO on parallel processing and the requests service process with extensive experiments.

Efficient service reconfiguration with partial virtual network function migration

Network Slicing (NS) technique is comprehensively reshaping the next-generation communication networks (e.g. 5G, 6G). Software-Defined Networking (SDN) and Network Functions Virtualization (NFV) predominantly control the flow of service functions on NS to incorporate versatile applications as per user demands. In the virtualized-Software Defined Networking vSDN environment, a chain of well-defined virtual network functions (VNFs) are installed on Service Function Chains (SFCs) by multiple Internet Service Providers (ISPs) concurrently. Generation, allocation, re-allocation, release and destroying associative VNFs on SFC is an extremely difficult task while keeping high selection accuracy. Towards solving this fundamental issue, in this work, we have proposed a multi-layered SFC formation for adaptive VNF allocation on dynamic slices. We have formulated an ILP to address the VNF-EAP (VNF-Embedding and Allocation Problem) over real network topology (AT&T Topology). Leveraging machine learning techniques we have shown an intelligent VNF selection mechanism to optimize resource utilization. The performance evaluation shows remarkable efficiency on ML-driven dynamic VNF selections over static allocations on SFCs by halving resource usage. Further, we have also studied a VNF typecasting technique for service backup on outage slices in the field of disaster management activities.