A Link-Layer Virtual Networking Solution for Cloud-Native Network Function Virtualisation Ecosystems: L2S-M  
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lightweight in comparison with traditional virtualisation platforms based on hypervisors. Containers can be exported to other virtualisation platforms with enough computational, networking and storage capacity to run them. Furthermore, they are able to pack the required software to execute every microservice independently from the rest since their own containers have all the software needed to run the service without the need for emulating an entire operating system. In the same fashion, containers offer a scalable solution that allows to flexibly adapt a service to its demand. For example, if an application experiences a sharp increase in traffic, new containers can be quickly deployed to provision for this demand, minimising service cut-offs. Given the rise in the popularity of container technology, there are several platforms that allow the management and orchestration of containers, both open source, such as Kubernetes (K8s) [4], Docker Swarm [5] or OpenStack [6], as well as solutions offered by cloud providers, like Google Kubernetes Engine [7] or Amazon Elastic Kubernetes Service [8]. It is worth mentioning that K8s has become the most popular tool in the service cloud-native market. According to the 2021 survey of CNCF [9], performed over the global cloud-native community (including software and technology, financial services, consultancy and telecommunication organisations), 96% of the surveyed reported the use of K8s in their organisation. The rise of the cloud-native model has provided multiple benefits for the deployment of Internet services. However, microservice technologies have also been regarded as excellent candidates for the deployment of network functions in cloud-native environments for the next generation of mobile networks (5G and 6G). The network function virtualisation (NFV) paradigm has greatly assisted in the agile deployment and development of network services (NSes) in both cloud and edge environments. NFV aims at the softwarisation of network services and functionalities through the use of virtualisation technologies, such as virtual machines (VMs), reducing the deployment and development costs since it is not necessary to develop and maintain the dedicated hardware involved in the provision of some network functions. Naturally, containers have been regarded as the next step for the deployment of NSes under the NFV umbrella since their lightweight nature and easier management can enhance the provision of NSes in comparison with more computationally demanding solutions. Naturally, the provision of network services involve certain degree of orchestration between containers to ensure its proper functionality. In this regard, microservice platforms like K8s are excellent candidates for this purpose, thanks to their orchestration and abstraction tools (automated rollouts and rollbacks, self-healing properties, service discovery...) that assist in the swift and efficient deployment of NSes in data centre environments, allowing microservices to properly interact with each other to offer a complex application. Some examples of NSes that could be deployed using NFV technologies include load balancing, service discovery and routing functionalities. All these services must be connected to one or several virtual networks able to isolate each VNF in different local area network (LAN) domains. This behaviour provides these functions with a finer control of their networking aspects within the platform where they are deployed, regardless of their location.