The upcoming generation of mobile telecommunication systems is expected to support new use cases, where the mobile network serves one or more IP subnetworks located behind the User Equipment (UEs). This would create new challenges for the mobile system to efficiently serve such behind-UE subnetworks, as the latter are commonly not visible to the mobile system. In 3GPP, there have been works on Time-Sensitive Networking (TSN) and Deterministic Networking (DetNet), where the 5G System (5GS) is considered as a bridge or a DetNet node. In order to efficiently serve behind-UE IP subnetworks, we foresee the need for a further generalization where the mobile system (5GS and beyond) acts as a set of IP routers with more generic capabilities. In this article, we introduce the concept of Mobile System Router (MS-Router) which aims to provide a reference architectural design to enable the support of IP routing in the next generation of mobile telecommunication systems. The concept models a mobile system as an IP router per User Plane granularity. Each MS-Router implements an IP routing protocol, exchanges routing messages with the external routers and constructs a routing table, enabling the mobile system to dynamically learn the topology of the IP subnetwork behind the UEs and Data Network. The learned topology is translated into User Plane configuration to serve the IP subnetworks in an optimal way. The article also advocates different approaches where routing protocols can be implemented in the mobile system.

翻译：即将到来的新一代移动通信系统预计将支持新的应用场景，其中移动网络需服务于位于用户设备（UEs）后端的单个或多个IP子网。由于这些后端子网通常对移动系统不可见，这将为移动系统高效服务此类子网带来新的挑战。在3GPP中，已有关于时间敏感网络（TSN）和确定性网络（DetNet）的研究工作，其中5G系统（5GS）被视为网桥或DetNet节点。为高效服务UE后端的IP子网，我们预见需要进一步泛化，使移动系统（5GS及后续演进）能够作为一组具备更通用能力的IP路由器运行。本文提出移动系统路由器（MS-Router）的概念，旨在提供参考架构设计，以实现在下一代移动通信系统中支持IP路由。该概念将移动系统建模为按用户平面粒度划分的IP路由器。每个MS-Router实现IP路由协议，与外部路由器交换路由消息并构建路由表，使移动系统能够动态学习UE后端及数据网络中IP子网的拓扑结构。学习到的拓扑信息将转化为用户平面配置，从而以最优方式服务IP子网。本文还探讨了在移动系统中实现路由协议的多种可行方案。