Opportunities and challenges of POL campus networks
In recent years, in the construction of campus networks, POL (Passive Optical LAN) solutions have increasingly become the first choice of customers, and the construction of all-optical campus networks has become a unified understanding of the industry. Compared with the traditional Ethernet LAN, POL has the characteristics of high security, low energy consumption, long distance, long life, simplified network and centralized operation and maintenance. Based on long-term investment and technology accumulation in the development of PON access network in the home wide market, operators actively promote the construction of POL network in the park. For example, China Telecom ’s FIRST education private network uses PON technology, and the hotel industry has already covered PON networks on a large scale. The industrial Internet field has proposed the concept of industrial PON and has carried out standardization.
Compared with traditional home-wide PON access networks, POL uses the same PON technology, but faces a more complex networking environment and higher customer requirements. The POL campus network has the following basic characteristics and requirements.
1) There are many types of services, including office Internet services, security monitoring services, intranet voice services, industrial data acquisition services, and education private network services.
2) Diversified access terminals, including newly deployed ONUs, traditional Ethernet switches, wireless APs, industrial data acquisition terminals, etc.
3) High security and reliability requirements. It must not only resist external network attacks, but also prevent internal illegal user access and unauthenticated terminal access. High reliability requires network-level and equipment-level redundancy protection, especially in the industrial field, which requires 99.999% system availability.
4) Operation and maintenance management requirements are convenient and fast. The campus network is a discrete market. The main operating body can be the operator’s maintenance, agents, park properties, or customer units. In order to reduce operation and maintenance costs, business deployment must be as simple as possible and operation and maintenance management must be as convenient as possible.
5) Integrated wired and wireless access. Campus Wi-Fi coverage requires the deployment of a large number of wireless AP devices, including the deployment of 5G private networks. POL must address the regulatory challenges posed by these heterogeneous network devices.
6) Application of edge computing technology. A typical edge computing application is video surveillance image recognition. Based on data security requirements, edge computing facilities need to be deployed inside the campus.
7) Low latency requirements. The industrial control system with high precision requires the delay of the control network to be less than 1 millisecond. The traditional PON technology cannot fully meet the requirements.
In addition, in specific scenarios, multi-tenant management in large industrial parks, the integration of factory digital management and industrial control systems, and the convenient provision of hotel room voice services are the basic needs of current customers.
To realize the vision of all-optical campus coverage, the new generation of green POL campus networks must meet the basic needs of customers such as security and easy maintenance, as well as the capabilities of embedded computing, low-latency PON, and 5G convergence.
Open POL Campus Network
In the traditional POL network, the OLT is just a service transmission pipeline, the equipment functions are solidified, and new service deployment is difficult. Customers need additional investment to build business systems such as network firewalls, wireless controllers, information management systems, and softswitch fixed-line systems. These systems are usually installed on separate servers. These independent devices form a complex network, increasing Cost of network deployment and operation and maintenance.
As the world’s leading provider of PON network equipment, ZTE introduced the IT infrastructure into the OLT for the first time. With the design of a built-in blade board, ZTE can virtualize independent physical equipment (such as security firewalls, wireless controllers, etc.) as needed The software VNF is applied and installed in the PON network, forming an open network that is simple, easy to upgrade, easy to modify, and easy to add new functions. Innovative POL technology solutions will help customers build open POL campus networks.
The open POL campus network creates a lot of value for customers.
Security enablement: Install a virtual firewall to implement online authentication and defense against network attacks for intranet users.
Computing Empowerment: Deploy edge computing on the OLT to achieve the best balance between performance and cost.
Wireless management and control: OLT integrates vAC application to realize unified management of campus AP equipment.
End-to-end slicing: Provide blade computing resources to meet the needs of slicing and achieve the requirements of secure isolation and differentiated QoS between different services.
Simplify operation and maintenance: Simplify the network through virtualization, and the operation and maintenance work is concentrated on the OLT equipment, which reduces the operation and maintenance workload.
Low-latency POL campus solution
The PON technology uses the working mode of uplink TDM. In order to discover the newly accessed or newly powered ONU in time, the OLT PON port side needs to open the window regularly (such as every 1 to 10 seconds) so that the new ONU can complete the registration required to access the OLT , Ranging and other processes. During the window opening period, all ONUs in a normal working state suspend sending uplink data. According to the standard, a window period of 250 microseconds will cause a delay of 250 microseconds to the ONU.
In order to eliminate the delay caused by the PON window registration mechanism, ZTE relies on its years of accumulation in the PON technology field, following the first proposal and release of the Combo PON solution, and innovatively proposes a low-latency PON solution. In the low-latency PON solution, the OLT side uses a Combo PON, and the ONU side introduces a low-latency ONU. The 10G PON channel of the Combo PON is used for forwarding services, and the GPON channel is dedicated to the control and management information of the PON, which greatly reduces Service forwarding delay. The 10G PON delay has been reduced from milliseconds to less than 100 microseconds, meeting the low latency requirements of industrial control.
The low-latency PON technology expands the application field of PON to the fields with severe delay requirements, which lays the foundation for building an all-optical campus network.
Convergence of POL campus network and 5G technology
Compared with Wi-Fi, 5G has two advantages of low latency and anti-interference. It is a trend to apply it to the campus private network, and the industry is actively exploring it. The 5G outdoor macro station & room sub-system is deployed in the open POL campus. Through special frequency points, it can solve the scenario requirements that Wi-Fi cannot meet. OLT can integrate lightweight 5G UPF and access 5G DU facilities to form a POL + 5G wired and wireless integrated next-generation campus solution.
Relying on the ability of end-to-end complete solutions, ZTE plans to deploy in important areas such as management and control, PON, switches, and 5G, and continuously promotes the technological evolution of open POL enterprise campus network solutions and implements the vision of “5G changes society”.