Identify the problem and find the right solution
The school campus network was built in 1995. After nearly 30 years of construction, it has become a large-scale campus network. With the deepening of new education infrastructure and digital transformation, the limitations of traditional campus networks have become prominent and have become a focus of attention for teachers and students.
The number of terminals has grown 10 times, the original wireless network is difficult to carry, and teachers and students have a poor network experience
Since 2015, the school has started to build a wireless network. The original intention of wireless network construction was to effectively supplement the wired network. After the first and second phases of the project, more than 2,000 wireless APs were deployed in the public areas of teaching offices, solving the problem of wireless network on campus. With the rapid development of information technology and the popularization of mobile terminals, the number of wireless network terminals on campus has increased nearly tenfold compared to 2015. Mobile terminals have become the main users of the Internet, and wireless Internet has also evolved into the main way to access the Internet on campus. Teachers and students have higher expectations for the quality of wireless networks, which has posed a huge challenge to the carrying capacity of the original wireless network, and the expectation of improving the quality of wireless networks has also increased.
This poses a huge challenge to the carrying capacity of the original wireless network, and the expectation for improving the quality of the wireless network has increased accordingly. Improving the wireless network experience has become the focus of teachers and students.
Multi-stage construction, complex network structure, and tight pipe and bridge resources
Over the years, with the continuous expansion of the network, the campus trunk ring network pipelines and bridge resources of each building have been tight, especially in the student dormitory area, where the bridges and cable ducts in the building are almost fully loaded. At present, the school's wired network information points exceed 50,000, with a large scale and complex structure. Due to the phased construction, some areas far away from the core of the campus network still have single point failures, lack of line redundancy, and bandwidth and performance bottlenecks. The above phenomena bring hidden dangers to the safe and stable operation of the campus network, and network transformation is imperative.
Dormitory buildings are densely populated, and the stability and safety of weak-current power supply in the dormitory room needs attention
The school has a total of about 9,500 student dormitories. The dormitory buildings are densely populated, with a total of 158 weak-current rooms, many of which are small and have poor power supply stability. For the expansion of star-shaped network topology, unstable power supply will directly affect the networking of all devices downstream of the key nodes, and in severe cases will cause the entire area network to be interrupted. As a key infrastructure deployment site for network, communication and security systems, the stability and safety of power supply in the weak-current room in the dormitory area has always been a concern for us.
Network fault location is cumbersome, and maintenance methods are backward
The school's multi-stage campus network construction has resulted in different network equipment manufacturers, models, and performance at each stage, and a complex network structure. Most of our maintenance methods are still done manually, which is inefficient. Due to the lack of an active alarm mechanism for smart network management software, repair reports need to be manually checked step by step, from core equipment to aggregation layer, and then to access layer. This not only affects the rapid recovery of the network, but also increases the maintenance burden. When faced with high-bandwidth and low-latency scenarios such as video conferencing and online live broadcasts, the maintenance work is stressful.
Multi-party argumentation, seeking innovative solutions
Based on the "One Network" construction goal in the school's "14th Five-Year Plan for the Construction of Smart Campuses" and the needs and expectations of teachers and students for the use of the Internet, the Information Management Center conducted research on all teachers and students. An online Internet demand survey was conducted through the "iNanjing University of Technology" platform, and verification forms were issued to each secondary unit through the "Smart Nanjing University of Technology" Internet Office to confirm the Internet usage scenarios of each building room. At the same time, we visited sister schools to learn about the construction and application experience of the new generation of campus optical network technology, and invited peer experts to conduct argumentation to provide advice and guidance for the construction of all-optical networks. After more than half a year of in-depth design,
After comprehensively considering the current situation, future development, long-distance transmission requirements in the 10G era, construction costs, security, maintenance costs, and rationality of network structure, we finally decided to adopt the minimalist Ethernet color light solution to comprehensively upgrade the dormitory and office area networks of the Jiangpu campus, covering more than 14,000 rooms, involving 23 types of room usage functions, and 10 network maintenance scenarios, in order to achieve high-bandwidth management of broadband network construction.
Figure 1: Nanjing University of Technology Campus Network Architecture Design
The school's entire network adopts a large two-layer structure. The core side of the office area and dormitory area uses VSU technology to deploy two hyper-converged core switches in different computer rooms, which are all-optically interconnected with the access layer equipment; 5 sub-aggregation computer rooms are selected in the dormitory area and office area to deploy corresponding hyper-converged switches according to the number of terminal devices within the managed building range; the aggregation in each building uses passive transparent aggregation equipment deployed at the optical fiber aggregation node in the building; the terminal access equipment is moved from the traditional deployment in the building's weak current room to the user's indoor equipment, and the indoor equipment is connected to the building's passive aggregation equipment via optical fiber.
Every 8 access devices are aggregated into a core trunk optical line to the distribution and aggregation room. The access layer deploys corresponding indoor devices according to the network requirements of different scenarios (as shown in Figure 2). Regardless of the type of indoor devices, a unified power supply solution is adopted. The dormitory area adopts centralized voltage reduction to supply 48V DC power to the indoor optical AP; the scenarios where optical switches are brought into the classroom, such as the classroom, use a centralized power supply room to supply power to the DC power supply or other
A passive optical network builds a high-speed, secure digital base
This all-optical network construction is the largest and most expensive single information construction project in the school in the past 10 years. After half a year of construction, the campus network has realized the main network flattened network architecture, and resources between the south and north campuses are interconnected and shared across the river. The current operation effect is good, mainly reflected in the following four aspects:
One fiber per room, one device per room, high-performance Wi-Fi full coverage
The campus network upgrade has achieved resource optimization and significantly improved network performance. The link bandwidth of the cross-river campus has increased from 40G to 400G, the backbone from the main network core to the aggregation point has increased from 10G to 200G, and the network export bandwidth of the teaching office area has also been expanded from 8G to 12G, ensuring high-speed interconnection and stable operation of the network.
The introduction of optical fiber into the room provides each room with at least a gigabit network access at this stage, laying the foundation for future high-bandwidth application scenarios. The all-optical network upgrade supports the deployment of Wi-Fi 6 and Wi-Fi 7, especially in teaching offices and high-density places, providing sufficient bandwidth and stable wireless access guarantees. Mobile phone Wi-Fi online has become the norm in the school. Smart classrooms enjoy 10G optical switching into the room, and terminals can be added or changed at will.
A durable, easy-to-expand high-bandwidth network environment has been built. The dormitory area has achieved a 300% increase in dormitory network speed through the minimalist deployment of "one room, one fiber, one room, one device". The indoor AP installation is also more concise and beautiful, which greatly improves the students' Internet experience.
All-optical network, passive in weak current room, 1:8 convergence of main optical fiber
The all-optical network construction introduced Ethernet color optical technology to innovate and upgrade the campus network. The use of super-aggregated color optical switches and color optical modules transmits 8 pairs of optical signals of different wavelengths to each building through one optical fiber, effectively saving backbone optical cable resources, and doubly improving link efficiency and bandwidth performance; passive transparent aggregation equipment is used in each building, and then the 8-wavelength optical signals on one optical fiber are separated to different rooms, so that full-link optical and electrical separation can be achieved in each building, and the intermediate link is passive from the regional aggregation point to the indoor entrance, effectively reducing the chain network failure caused by the power failure of the intermediate node of the link, and at the same time greatly reducing the fire safety hazards in the weak current room.
Centralized power supply at the access layer, separation of optical and electrical, safe and reliable
In the construction of the all-optical network, the innovation of power supply design is particularly prominent. We have customized three power supply solutions according to different scenarios: 220V AC centralized power supply, terminal voltage reduction, 220V AC centralized power supply + PoE power supply, and 48V DC power supply after centralized voltage reduction. Among them, the 48V DC power supply after centralized voltage reduction is very worthy of promotion. This power supply method is mainly suitable for dormitory scenarios and some public places. Its deployment method is to deploy passive transparent convergence in the weak current room of the building, and deploy centralized voltage reduction power supply equipment in the strong current room, so as to realize the separation of data and power supply of the equipment, and the data takes the link between the weak current room,
The whole process is passive, and the power supply is through a strong power chain. The school has entrusted the unified management to the logistics department to ensure the reliability and safety of the power supply. The advantage of this power supply solution is that after the voltage is reduced, the indoor power supply is 48V DC, which is safer than 220V AC power supply, and can also avoid the risk of illegal use of electricity in student dormitories. In dormitory scenarios, we have deployed more than 600 centralized power supply devices in total. The output power of a single device is 600 watts, which can provide 48V DC power to the panel APs in 24 dormitories. In public areas such as canteens, libraries, and lecture halls where high-density APs are deployed, a single power supply device can support the power supply needs of about 8 high-density APs.
Smart maintenance, one picture for the whole network, no-feeling processing, good experience for teachers and students
The SDN smart maintenance tool used in this all-optical network construction is INC (Intention Network Commander), which can provide integrated visual smart operation and maintenance for the entire wired and wireless network, support plug-and-play access equipment, and configuration-free online. Fault detection can be completed in three steps: checking the link, checking the status, and changing the device. After the new equipment is connected to the optical network, the configuration is automatically issued without manual intervention, allowing us to shift the focus of the operation and maintenance of the information department from the device side to the client side. According to the school's requirements, the SDN tool is equipped with customized functions to realize the management of the original school's wired network, with one picture for the entire network, and teachers and students get a "no-feeling processing" network security experience.
The construction of the all-optical network has ushered in a true upgrade of the campus network. The all-optical network is the "highway" for school information transmission. Its construction and commissioning provide a solid network infrastructure platform for the school's scientific research innovation, teaching reform and management services, marking a key step in the school's digital transformation journey, helping the school to improve its quality and upgrade its education, accelerate the process of digital transformation of education, and enable the school's inherent development with the digital artery.
