# SRv6-Based Edge Service Continuity in 5G Mobile Networks +
Footnote †: This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ([[https://creativecommons.org/licenses/by/4.0/](https://creativecommons.org/licenses/by/4.0/)]([https://creativecommons.org/licenses/by/4.0/](https://creativecommons.org/licenses/by/4.0/))). Footnote †: This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons. the user-assigned edge service may become too distant and cause higher latency. In this situation, another edge data center may be closer. The edge service should \"follow\" the client to preserve the Quality of Service (QoS). If services are stateful, moving the service along with its internal state is required. In this context, one way to achieve this mechanism is to wrap the service in virtual machines or containers and migrate the instance from the original edge site to a target one using existing methods to smoothly transfer the whole package [7]. The European Telecommunications Standards Institute Industry Specification Group (ETSI ISG) worked in the last decade to create a standardized, open, multi-vendor, and multi-access edge computing environment. The ETSI specifies the elements required to enable applications to be hosted in a multi-vendor multi-access edge computing (MEC) environment [8]. The MEC architecture provides cloud computing capabilities and a distributed environment at the edge of the network. The system consists of MEC Hosts dislocated at the edge of the network and connected through the underlay communication infrastructure. It provides advantages in terms of delay, network traffic, and data localization. The ETSI MEC has been identified as the key technology for supporting low-latency edge services in 5G networks. The ETSI MEC architecture provides a system orchestration mechanism that enables the management of service instances and their dynamic association with the user equipment (UE) [9]. The orchestration oversees the selection of the best MEC Host where a service instance should run in order to guarantee the application requirements' satisfaction. It is also in charge of triggering the proper network configuration through the 5G core (5 GC) in a centralized manner. The ETSI MEC environment also supports the service continuity required by user mobility in 5G networks. The MEC system, based on the information exchanged with the 5 GC network entities, verifies which is, at any time, the best MEC Host for an edge service. To guarantee the latency constraints, instance migration may be triggered [10]. MEC can guarantee service continuity by employing various techniques such as DNS and device-application interface solutions. Most of the proposed methods, however, require the active involvement of the client [11]. In line with the 5G requirements for a network that is highly scalable, maintainable, and programmable [12], Segment Routing over IPv6 (SRv6) has been recently proposed as the new data plane for 5 GC [13; 14]. SRv6 provides flexibility, programmability, scalability, and has great potential for further development, which are essential features of 5G networks. SRv6 Network Programming allows integrating functions, implemented as virtual network functions (VNFs), as part of the network node packet processing. SRv6 also facilitates the dynamic reconfiguration of the network, enabling seamless service continuity when edge services are migrated to follow their mobile 5G users. Enabling seamless service continuity means letting the client reach the edge service in its new location, while guaranteeing qualitative and quantitative requirements. For what concerns qualitative aspects, the service must be reached transparently to the client application logic, which is achieved through SRv6 by keeping the same IP address for the migrated service. Moreover, no packets should be lost during the service migration process.