SPN 2.0 Private Line: Creating Digital Intelligence Future

In the evolving information industry, the surging demand for private lines, ranging from high-speed to low-speed TDM lines, necessitates a versatile solution. The industry’s digital transformation mandates networks to deliver ultra-high-quality services, reduce costs, and enhance efficiency. SPN private lines, with flexible slicing options, cater to diverse service forms, meeting not only bandwidth and quality requirements but also addressing the comprehensive needs of industries. SPN ensures efficient bandwidth utilization, providing deterministic performance for TDM lines and large packet bandwidth. Moreover, enhanced management and control plane capabilities, coupled with intelligence, enable fast provisioning and visual performance, better meeting customer demands.

Development of SPN Technology

URLLC, eMBB and mMTC are key 5G application scenarios, with slicing and edge computing emerging as native technological features. In response to these new features, China Mobile introduces the concept of “lossless + efficient and flexible” transport, and partners with the domestic industry to build a new-generation transport network architecture known as slicing packet network (SPN).

SPN integrates TDM and packet networks, supports L0 to L3 capabilities, and offers advantages such as large bandwidth, low latency, network slicing, flexible connection, high-precision synchronization, and unified management and control. It minimizes network investments by reusing the Ethernet industry chain and achieves ultra-large bandwidth, addressing the issue of end-to-end efficient and lossless hard isolation transmission tailored to large 5 Gbps granularities. The SPN device using MTN channel cross-connection excels in performance with a single-node forwarding latency as low as 2.784 µs and ±5 ns time synchronization precision. Its slice isolation capability demonstrates minimal jitter (0.277 µs) before and after network congestion, which almost has no effect on the service. China Mobile has successfully deployed 400,000 SPN devices for 5G network backhaul since 2019, showcasing reliable and efficient operation.

In the thriving landscape of 5G vertical industries, government and enterprise services, and computing networks, SPN has transitioned into the SPN 2.0 era. This evolution brings increased slice granularity, enhanced service perception, flexible connection, ubiquitous access, intelligent O&M, and energy-saving technologies. A key aspect of SPN 2.0 is the introduction of SPN fine granularity unit (FGU). This innovation primarily addresses the demands for isolation, security, and reliability in fine-grained service transport in typical scenarios like government private lines, financial private lines, and large enterprise private lines.

The SPN FGU technology refines the granularity of hard slices from 5 Gbps to 10 Mbps. Its features and capabilities include:

• Fine-grained bandwidth to meet the bandwidth needs of diverse services: Bandwidth granularity is 10 Mbps, enabling flexible N×10 Mbps bandwidth allocation. Fine-grained channels exclusively use deterministic timeslots to provide strict TDM features. The timeslots of the egress and ingress ports on any node of a channel are allocated and fixed in advance at the management and control layer.
• Low latency and low jitter: Through TDM timeslot cross-connection, fine-grained services ensure deterministic low latency by avoiding the perception of packet messages. These services exclusively utilize timeslot resources in TDM channels, resulting in jitter far less than 1 µs.
• Independent and complete OAM capabilities provided by each fine-grained channel: OAM blocks are inserted into each fine-grained channel to provide connectivity detection, and fault and performance monitoring. This ensures protection switching within 50 ms.
• Hitless online channel bandwidth adjustment: The bandwidth of fine-grained hard pipes can be increased or reduced during normal service transport. This facilitates flexible bandwidth and timeslot allocation.

With the evolution to SPN 2.0, continuous enhancements have been made to meet the needs of fine-grained slicing for diverse services and provide flexibility and intelligence.

Emerging Requirements for Private Lines

As industries undergo in-depth digital transformation, private lines show new demands and development trends.

The first demand is for integrated network transport accessing diverse services via private lines and networks. For instance, in the energy industry, typical services like power distribution automation, data network dispatching, power consumption collection, data communication network, video services, primary network relay protection channel, and Wi-Fi6 inspection robots have varied requirements in terms of latency, reliability, rate, and connection density. Therefore, it is necessary to utilize network resources to achieve unified transport of differentiated services on the same network.

The second demand is for deterministic networks, especially for control and transaction services in areas such as financial services, where low and deterministic latency, high reliability, and security are crucial. Despite not requiring high service bandwidth, financial services demand stringent network security.

The third demand is for ubiquitous access and fast provisioning capabilities. As industry networks evolve towards cloud and flat architectures, the surge in edge nodes and cross-area/cross-city service connections intensifies the complexity in network connections. Edge access may integrate wireless and wired access, so it is necessary to meet ubiquitous access and rapid provisioning needs of these numerous edge nodes.

The fourth demand is for end-to-end services rather than pipe services, emphasizing comprehensive customer services, like visual indicators and fast troubleshooting. Visual indicators rely on precise monitoring of network SLAs and can be displayed on customer-oriented application interfaces.

These new demands propel advancement and innovation in private line technology.

Features and Advantages of SPN Private Lines

The technical features and advantages of SPN effectively meet the private line market’s development demands. SPN can offers access to TDM hard slices while supporting high-bandwidth access of packet soft slices. This allows a single SPN network to offer integrated access for various customer services. Additionally, for highly demanding control services, SPN 10 Mbps fine-grained hard slices can be directly used to provide independent TDM channels, isolating physical timeslots from other services. China Mobile's SPN networks have extensive coverage in China, boasting over 400,000 SPN devices and the capability of ubiquitous access. The intelligent O&M capability of SPN has seen continuous improvement, with inband OAM supporting service-flow-level accurate performance monitoring. The standard northbound interfaces of the SDN-based centralized management and control system enable data entry to the orchestration system and upper-layer customer systems. Fig. 1 illustrates the network architecture of an SPN private line.

China Mobile has launched three SPN private line products based on SPN features: basic SPN private line, advanced SPN private line, and customized industry SPN private network. The basic version focuses on slice sharing, ubiquitous access, and fast provisioning. Industry users can share MTN slices, with isolation through VPN for users within the same MTN slice. The advanced version provides fine-grained MTN slices for single-user dedication with ultra-high determinacy. Customized industry SPN private networks meet specific customer requirements, allowing the selection of hard or soft slices, and are physically isolated from other user slices.

For enhanced adaptation to edge access in SPN private lines, smaller SPN devices are developed in addition to metro SPN devices. These smaller devices feature reduced configurations and costs, with enhanced integrated access capabilities tailored for edge coverage. They offer small switching capacity, compact size, AC power supply, and low power consumption to meet the requirements in edge scenarios. Interconnected through NNIs, small SPN devices and metro SPN devices provide end-to-end Ethernet fine-grained hard slices and slice-based hitless bandwidth adjustment for high-value user demands. Small SPN devices must provide standard southbound interfaces and unified management and control capabilities to facilitate orchestration and control.

Private line technologies have enhanced forwarding layer capabilities and are advancing end-to-end intelligent services. Key improvements include enhancing the intelligent management system, automating interfaces for customer service integration, and timely display of private line commissioning, operation status, and fault locating on customer interfaces. Collaboration among intelligent systems at network equipment, management and control, and platform levels is essential. Collecting comprehensive historical and current data enables efficient control, analysis, prediction of risks, and enhanced user experience. As intelligent management and control capabilities advance, the efficiency of network OAM and private line services will see continuous enhancement in the future.

Conclusion

As a 5G mobile backhaul network innovation, SPN efficiently caters to 5G commercialization needs. Amid the digital transformation of industries, private lines seek integrated network transport, deterministic latency, ubiquitous access, fast provisioning, and end-to-end intelligent services. SPN 2.0, centered around fine-granularity hard slicing, addresses these market demands. China Mobile offers a range of SPN private line products including basic SPN private line, advanced SPN private line, and customized industry SPN private network, to support the transport of diverse private line services and create China’s digital intelligence future.