SPN 2.0: Empowering Various Industries

In June 2022, China Mobile, along with partners including ZTE, released the slicing packet network (SPN) 2.0 White Paper, marking the beginning of the SPN 2.0 era. The SPN 1.0 technology has been widely used by China Mobile and other operators for carrying 5G backhaul services and has been increasingly adopted by vertical industries such as subway, mine, and expressway. With the gradual deployment of China Mobile’s metro private line services on SPN networks and the growing transport demands of China Mobile’s metro computing power networks, SPN technology is evolving towards integrated service transport.

SPN 2.0 aims to build an integrated transport platform that integrates TDM and packet multiplexing technology for metropolitan area networks and industry private networks. It focuses on high-value slicing private lines, slicing private networks that empower industrial digitalization and new computing-network convergence services. To support high-value slicing private lines, SPN 2.0 has introduced the 10M fine-granularity unit (FGU) technology, which achieves or even surpasses the quality of MSTP private lines. Miniaturized SPN devices have been also introduced to provide fine-granularity access and increase SPN coverage. To meet the needs of slicing private networks empowering industrial digitalization, SPN 2.0 provides both soft and hard isolation, along with deterministic reliable communication, through the deep integration of TDM and packet technologies. In terms of the evolution of computing power networks, SPN 2.0 proposes transport SRv6 (T-SRv6) and native AI technologies to support new service transport.

High-Value Slicing Private Lines

The SPN 2.0 private line technology, centered on the metro transport network (MTN)/FGU slice channels, provides hard isolation, multi-service transport, inband OAM-based quality perception, as well as various network protection and self-service functions. This technology meets the demands of fixed private lines, 5G private lines, and cross-provincial backbone end-to-end private lines with miniaturized SPN devices.

At present, ZTE has deployed SPN private lines to carry enterprise customer private line services for China Mobile across a number of provinces. ZTE has cooperated with China Mobile on enterprise standard formulation, prototype R&D, and pilot tests of miniaturized SPN devices, thereby expanding the coverage capabilities of SPN private lines. In addition, leveraging the construction of provincial and national SPN backbone networks, ZTE is committed to enhancing the end-to-end fine-granularity private line technologies for cross-domain SPN networks to achieve full private line coverage throughout the entire network. The FGU-based SPN 2.0 private line transport solution is shown in Fig. 1.

Private Networks Empowering Industrial Digitalization

With the development of new infrastructure like 5G, industrial private networks have evolved from single-service private networks to integrated service private networks and virtual private networks. At present, the demands for private networks driving industrial digital transformation mainly include highly reliable and secure communication in the production field, broadband connection for production aid, interconnection of cloud-based applications, and manageable & controllable networks.

Traditional SDH/OTN technologies provide highly reliable and secure communication but lack sufficient packet transport capability. Ethernet/IP technologies excel in L2/L3 cloud-based interconnection but lack the capability of hard isolation crucial for highly reliable communication. SPN, which deeply integrates packet and TDM, addresses the key demands of new industrial private networks by incorporating hard isolation and high reliability into the packet architecture.

SPN offers diverse slicing capabilities. FGU-based hard isolation slicing meets the low latency and low jitter requirements of production services, and delivers carrier-class OAM and protection. MTN-based hard isolation slicing provides high packet bandwidths to meet the requirements of production aid services. Packet-based soft isolation slicing supports complete L3 connection capabilities and  high-precision inband OAM to meet the interconnection requirements of cloud-based applications. Furthermore, SPN includes the transmission network management function, supports integrated SDN management and control, and features the intelligent management and control capability to ensure a controllable and manageable network.

Currently, SPN products have been commercially deployed in private networks within subway, mine, and expressway industries. China Southern Power Grid and State Grid are using SPN to carry integrated power services, while China’s National Railway Administration is considering SPN as the major access transport technology for building the 5G-R next-generation railway integrated transport network.

Evolution of Computing-Network Convergence Services

The development of China Mobile’s computing power network technologies has spurred the demand for SRv6 technology evolution in metro SPN. ZTE and China Mobile has proposed the T-SRv6 solution based on the characteristics of SPN networks. T-SRv6 accurately binds SRv6 services with the SPN slicing channels by extending the programmable END.BXC function of SRv6. This solution combines standard SRv6 technology with transport slicing technology, creating an SRv6 solution with transport features aligned with the requirements of new computing power networks such as hard isolation, zero packet loss, deterministic latency, and high-quality differentiated slicing services. Through the implementation of the T-SRv6 solution, SPN 2.0 offers the open slicing capability, agile end-to-end SRv6 interconnection, high quality, differentiated service, and programmable features.  The T-SRv6 solution is illustrated in Fig. 2.

ZTE has completed the R&D of the key END.BXC function extension of T-SRv6 based on the standard SRv6 programmable architecture. At the same time, ZTE and China Mobile have also submitted a draft at the IETF SPRING working group. The pilot tests of the phase-1 T-SRv6 transport solution were successfully completed in the existing network of China Mobile in September 2022.

Native Computing Power and AI

In addition to the evolution of computing-network convergence services, SPN 2.0 also focuses on utilizing native computing power and AI capabilities to improve the intelligence and adaptability of SPN. As a deployment form of hyper edge computing (HEC), the built-in lightweight AI computing power of SPN 2.0 has been successfully piloted to provide computing and network convergence services for ToB industry applications. In September 2022, China Mobile and ZTE jointly completed the first pilot of the Cloud SPN computing-network convergence solution in Changzhou, Jiangsu province. This pilot facilitated the upgrade from the traditional quality inspection to the AI-enabled one in industrial manufacturing and will be promoted in the future.

In terms of SPN 2.0 management and control with AI, the industry has set the   autonomous level improvement goal,  providing a continuously evolving intelligent SPN management and control solution. In 2022, ZTE and China Mobile Liaoning jointly launched an intelligent closed-loop system solution for service quality assurance, and successfully verified this solution on ZTE’s existing intelligent management and control system, ZENIC ONE (UME). This solution changes manual and passive O&M to automatic and active O&M in some scenarios, increasing network maintenance efficiency and service security, reducing customer complaint rates, and improving customer satisfaction.

Moreover, the industry has begun to harness the power of native AI in SPN devices to create an intelligent energy-saving solution. AI is used to adapt to the tidal traffic patterns of the existing network, collect network data in real time and analyze service load changes. Multi-layer energy-saving solutions have been developed at the chip, module, board, and network levels to achieve intelligent power saving while strictly guaranteeing the transmission performance of the transport network. This innovative intelligent energy-saving solution has been piloted and tested in China Mobile’s existing network in 2022. Preliminary verification results indicate an energy-saving effect of 15%.

SPN 2.0 Technology Progress

SPN technology has been applied on a large scale in China, with smooth progress in both domestic and international standardization efforts. The standard on SPN 1.0 was released by China Communications Standards Association (CCSA) in 2021, while the ITU-T MTN standards, including G.8310, G.8312, G.8321, G.8331, and G.8350, were all released by September 2022. Currently, CCSA is in the process of releasing standards for SPN 2.0 FGU. The enterprise standards for miniaturized SPN and computing-network SPN of China Mobile have basically been formulated. Additionally, ITU-T has approved FGU as a new work item. Complemented by the drafts of IETF series standards, SPN 2.0 is expected to further enrich the SPN standards system.

With the application of SPN products in the industrial sector, the Alliance of Industrial Internet in China has released a research report that summarizes SPN's application in industrial scenarios. The 5G transport group of IMT-2020(5G) Promotion Group's 2022 research report on 5G-R transport technology and network management & control solution has identified SPN as the most preferred technology. In 2022, the SPN 2.0 solution was awarded the “Most Innovative Network Slicing Case” at the Network X held by Informa in Netherlands, highlighting the global recognition of SPN technology. As the SPN 2.0 technologies and solutions continue to be adopted by operators and integrated into industrial private networks, SPN technology is poised to enter a new stage of development, empowering various industries and shaping an intelligent digital future.