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Abstract-A new era in telecommunications is emerging. Virtualised networking functions and resources will offer network operators a way to shift the balance of expenditure from capital to operational, opening up networks to new and innovative services. This paper introduces the concept of Edge-as-a-Service (EaaS), a means of harnessing the flexibility of virtualised network functions and resources to enable network operators to break the tightly coupled relationship they have with their infrastructure and to enable more effective ways of generating revenue. To achieve this vision, we envisage a virtualised service access interface that can be used to programmatically alter access network functions and resources available to service providers in an elastic fashion. EaaS has many technically and economically difficult challenges that must be addressed before it can become a reality; the main challenges are summarised in this paper.

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Network Service Providers (NSPs) envisage to support the divergent and stringent requirements of future services by instantiating these services as service chains, commonly referred to as Service Function Chains (SFCs), that are customized and configured to meet specific service requirements. However, due to the limited footprint of the Infrastructure Providers (InPs), these SFCs may have to transcend multiple InPs/domains. In this regard, determining the optimal set of InPs in which to embed the SFC request emerges as a complex problem for several reasons. First, the large number of possible combinations for selecting the InPs to embed the different sub-chains of the request makes this problem computationally complex, rendering optimal solutions only after long computations, especially in large scale networks, which is unfeasible for delay sensitive applications. Second, the unwillingness of InPs to disclose their internal information, which may be vital for making embedding decisions, usually implies the provisioning of single-domain solutions, which are unsuitable in this working scenario. In this regard, this paper first formulates the multi-domain service deployment problem under multiple request constraints, such as bandwidth or delay, among others. Then, due to the NP-hardness nature of the above problem, this paper proposes an algorithm that is aided by a multi-stage graph for computing a request embedding solution in a distributed manner, solving the problem in acceptable run-times. Results from different simulations reveal that the proposed algorithm is optimized in terms of acceptance ratio and embedding cost, with up to 60.0% and 88.7% improvements in terms of embedding cost and execution time, respectively, for some scenarios, in comparison with a benchmark state-of-the-art algorithm.

In Network Virtualization Environments, the capability of operators to allocate resources in the Substrate Network (SN) to support Virtual Networks (VNs) in an optimal manner is known as Virtual Network Embedding (VNE). In the same context, online VN migration is the process meant to reallocate components of a VN, or even an entire VN among elements of the SN in real time and seamlessly to end‐users. Online VNE without VN migration may lead to either over‐ or under‐utilization of the SN resources. However, VN migration is challenging due to its computational cost and the service disruption inherent to VN components reallocation. Online VN migration can reduce migration costs insofar it is triggered proactively, not reactively, at critical times, avoiding the negative effects of both under‐ and over‐triggering. This paper presents a novel online cost‐efficient mechanism that self‐adaptively learns the exact moments when triggering VN migration is likely to be profitable in the long term. We propose a novel self‐adaptive mechanism based on Reinforcement Learning that determines the right trigger online VN migration times, leading to the minimization of migration costs while simultaneously considering the online VNE acceptance ratio.

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The Xcoop specification presented in this article is a step ahead in the evolutionary process of this system interface. Distinguishing it from previous work, it permits interactions between management systems independent of the underlying network technology -ATM, SDH, or hybrid. This is achieved by defining the appropriate functionality and presenting an information model, where, in fact, the specific characteristics of the ATM and SDH resources are abstracted and merged in common classes.The work presented here was undertaken as part of the EU ACTS project MISA [6] and is focused on the requirements, specification, and implementation of an Xcoop interface for ATM and SDH networks. The next section presents an overview of topics to cover in the context of multidomain management. In the following one, the MISA approach is presented as a solution for the ongoing challenges. Finally, the last two sections are devoted to the Xcoop interface itself and also include a scenario involving the key MISA components in a representative network environment. lSSUES IN MULTIDOMAIN NETWORK MANAGEMENTBy selecting a business case rather than a technical one, we consider how a value-added service provider (VASP) can offer one-stop shopping for videoconferencing services. These services could be directed to international corporations for which videoconference services can provide advantages, such as security companies, hospitals, manufacturers offering remote repair services, educational institutions, and entertainment enterprises. To provide these videoconferencing services, the VASP should use bearer connectivity services provided by public network operators (PNOs). From the VASP point of view the services should exhibit, among other properties, seamless international coverage, broadband connectivity, and easy access through defined service access points (SAPs). These S A P s should fulfill the VASP users' needs, allowing them the service specification in terms of quality of service (QoS), bandwidth, scheduling, and other requirements. In the context of this article, these types of services are referred to as broadband connectivity services (BCS). The above commercial example is just one among many IEEE Communications Magazine

Cognizant of the ease with which softwarized functions can be dynamically scaled according to real time resource requirements, and the fact that multiple services can have common VNFs in their chaining, this paper tackles the problem of cost effective deployment of online services from the perspective of sharing their VNF instances. First, we formally formulate the deployment problem under VNFs sharing. Secondly, given the NP-hard nature of the above problem, we propose a reinforcement learning (RL) algorithm capable of making intelligent placement decisions while considering multiple conflicting costs. Costs of transmission, VNF instantiation or energy consumption, among others. Thanks to the intelligence of the RL algorithm, simulation results show that the performance of the proposed algorithm is within a 14% margin and similar to an optimal solution in terms of request provisioning cost and acceptance ratio, respectively. Moreover, the algorithm results in more than a 20% and a 70% improvement in terms of request deployment cost and time compared to a state-of-the-art algorithm, and up to more than a 40% improvement in terms of cost compared to an algorithm that greedily minimizes the transmission or VNF activation costs.