Tips for choosing a network transmission device

Tips for choosing a network transmission device

[ Huaqiang Security Network News ]

In recent years, with the rapid increase of network bandwidth, computer processing capacity and storage capacity, and the emergence of various video information processing technologies, the advantages of the whole digital and networked video surveillance system have become more and more obvious, and its high openness and integration. And flexibility creates the necessary conditions for the overall performance improvement of video surveillance systems and devices. At this time, the signal transmission mainly uses various network signal transmission devices with network switches as the core. How to choose these network transmission devices?

First, it is conducive to high-definition video streaming

Tips for choosing a network transmission device

Although video streaming data is also the most common form of data in the network, it has its distinctive industry characteristics in security. In daily network data applications, if data loss occurs, or temporary pauses in data transmission are normal, no fuss, after we wait patiently for some time, the data will arrive at the designated location as it is, this is the IP network. The advantages. However, in security monitoring, we have higher requirements for data packet loss and transmission pause, because we are very real-time in the application! We don't want to suddenly get stuck while watching the video, and we don't want some important shots to be lost for no reason. Real-time, integrity, and fluency are the basic requirements for security surveillance HD video streaming, but it is easy to achieve this. The following is a few aspects to analyze the issues related to high-definition video streaming:

1. Equipment composition:

1): Acquisition terminal: The network camera is a new generation product combining traditional camera and network video technology. In addition to all the image capture functions of the traditional camera, the digital compression controller and WEB-based operating system are built in the machine. After the video data is compressed and encrypted, it is sent to the end user through a local area network, an Internet or a wireless network. Network cameras include: high resolution, simplified wiring, intelligent integration to the front end, intelligent integration, integrated audio, communication security, and strong scalability.

2): Transmission end: The important difference between the network camera and the traditional camera operating environment is that the signal transmission medium is different. The traditional camera transmits through video cable, twisted pair or optical fiber. Generally, each channel is transmitted by “special line”, and there is almost no transmission. Bandwidth constraints, while in network monitoring, each network camera needs to be transmitted through a network cable or other transmission device, and then connected through the switch to access the aggregation, so the special attention should be paid to its bit rate (bandwidth occupancy), because this It is the bottleneck of the network video surveillance system. There are many factors affecting the bit rate of network cameras and network video servers, including compression mode, resolution, frame rate, picture quality, picture complexity, and picture change.

3): Information center: The resolution of storage and display is also higher. The storage resolution is changed from CIF to D1, and gradually shifts to 720P and 1080P HD resolution. Since network cameras usually use dual-stream or multi-stream technology, video processing services such as near-end storage, video wall display, and video analysis use the main stream, high-resolution, high-definition and other features to provide huge services for these services. Convenience, while remote monitoring uses a secondary stream, usually with a lower resolution and a smaller transmission bandwidth. As the entire network video surveillance system, high-definition is the trend, high-definition images provide a good foundation for system intelligence, and provide the most important guarantee for the upgrade of the entire monitoring system.

2. Security monitoring system requirements for network bandwidth:

1): The video traffic is large: usually the D1 code stream reaches 2 Mbps, the 720P code stream reaches 4 Mbps, and the 1080P code stream reaches 6-8 Mbps. According to the 720P dual stream of each channel, a single stream requires 4 Mbps of code stream, and each network channel requires about 8 Mbps of code stream. If one stream is 720P and the other is 1080P stream, each channel stream will More than 10M network bandwidth. If it is an 8-port switch, the actual network bandwidth for the uplink port will be greater than or equal to 100M network bandwidth. Considering the reservations such as network packets and network switching, it is necessary to reserve a sufficient margin. It seems that the ordinary 100M home network switch can not meet the most basic bandwidth. In order to solve the problem of the bandwidth brought by the uplink of the video data, in the 8-port switch of the access layer, it is necessary to set two optical ports and one electrical port and two Gigabit uplink ports. The Gigabit uplink port can solve the problem of long-distance transmission of optical fiber, eliminating the Gigabit fiber transceiver and concentrating the video stream to the upper-level switch; and the Gigabit electrical port can be connected to the NVR for local-side storage.

2): Real-time requirements: There is a big difference between downloading video and network monitoring live video through the network. Generally, the network downloads a video to establish a large amount of cache locally. The lack of real-time network bandwidth and packet loss does not affect the real-time. However, for network video surveillance, there is no large cache, and it is necessary to forward the transmission data in real time. That is to say, in the same network environment, the same code stream video decoding and playback can smoothly play the network video, and the real-time network camera video plays a serious packet loss phenomenon. The current switch is basically a store-and-forward mechanism, and the size of the packet data cache affects the forwarding speed. At present, the 8-port switch cache commonly used in the market is generally 512K, which is still usable in network engineering. In network video surveillance, intermittent packet loss (cascading phenomenon) occurs. The actual test shows that if there are 8 720P or 1080P cameras, 1 NVR and 1 Gigabit fiber uplink switch, if you want to run smoothly, the packet data cache should be 1M or above.

3): Convergence ability: Although both are 2 Mbps streams, the network camera forwards the maximum network packet when each picture data is forwarded, that is, each packet size is 1K-2kbps, when each port is Forwarded with maximum data aggregation. Forwarding speed, forwarding buffer, and upstream bandwidth will constrain network aggregation capabilities. For example, when a 2 Mbps data stream is forwarded by a 10M network switch, the uplink channel (aggregation channel) takes more than 0.2 seconds, and 100M forwarding takes 0.02 seconds or more. If multiple channels are forwarded at the same time, you need to cache the port with a large enough port or large enough, otherwise it will delay or drop packets.

It can be seen that it is not an easy task to make the HD video stream “real-time, complete and smooth”. It is difficult for the common market-type switch to meet the security monitoring level. Therefore, when selecting the network transmission device, it must be Pay attention to whether this indicator meets the requirements.

Second, it is conducive to networking

The networking is mainly related to the transmission equipment and the network structure type. The relationship between the two is inseparable. To implement a certain structure, a network transmission device with this function is required. There are many types of network transmission equipment, including network switches, network transmitters, fiber optic transmitters, POE switches, and so on. According to the characteristics of security monitoring network, we can divide the whole network architecture into: network access part, network convergence part, core exchange part. Corresponding to the device can be divided into network access switches or devices, network aggregation switches, network core switches.

Various types of network transmission equipment:

The security monitoring network is similar to the common network, including the network access layer, network convergence layer and core switch. Because the application object in the security monitoring field is different from the computer in the ordinary network, it is to realize the webcam or other intelligence distributed throughout the country. Terminals are connected to the network, and most of these intelligent terminals are distributed outdoors, such as squares, parks, etc. Therefore, how to implement various types of terminal access network systems is more important, and the aggregation switch needs to be compatible with various network devices and provide sufficient size. Bandwidth and switching speed, core switches are basically similar to ordinary commercial switches. Generally divided into the following categories:

1) Network access switches and various access transmission equipment:

Due to the complexity of the monitoring environment, the following three problems are commonly encountered in access wiring and networking: network transmission distance, wiring method, and camera power. Distance refers to the distance between each terminal and the monitoring center, some are only a few tens of meters, while others are more than a few kilometers, dozens of kilometers; wiring means that in various applications have their own characteristics, there are The monitoring points are gathered together, and some monitoring points are scattered. Some monitoring points have certain geometric characteristics: such as ring or circle, which also bring difficulty to network networking and wiring; The camera or terminal will be installed outdoors or when it is difficult to get electricity. In some large-scale monitoring systems, these conditions usually appear in the project, which brings great difficulty to the project and installation, and cannot be solved by ordinary switches.

In order to solve the situation that network networking and wiring are difficult in security monitoring, the network speed and speed provides high-performance access switches, high-performance POE access switches and network transmission and power supply devices for various security media. The networking and access of various types of network terminals provide favorable support:

1) Access switch, downlink provides 10/100M network, uplink provides 100/1000M network, can well connect network terminals in the 150m range to the network, and provide both electrical and optical ports, which can be stored locally. Data can also be transmitted to the upper-level monitoring center via fiber optics. Products include 4-port, 8-port, 16-port and 24-port switches.

2) POE access switches, providing 10/100M network for downlink connection and 100/1000M network for uplink connection. It can provide network and POE (POE+ compatible) for network terminals up to 150 meters away. The uplink provides both electrical and optical ports, that is, data can be stored locally or transmitted to the upper-level monitoring center through optical fibers. Products include 4-port, 8-port, 16-port and 24-port POE switches.

3) Network extension of various media or network power extension equipment: Network extension methods can be selected according to distance and different occasions, including:

Coaxial Network Extender (EOC): Up to 1500 meters of network transmission.

Coaxial Network Power Extender (EPOC): It can realize multiple network terminal link network transmission within 300 meters and can supply power to near-end devices.

Coaxial video extender compatible with network and analog (EVOC): can transmit signals from a webcam and an analog camera within 500 meters.

Network optical transceiver: 10/100/1000M network transmission equipment of different distances such as 5km, 10km, 20km, etc.

Network Power Repeater (EP): It can realize multiple network terminal link network relay within 300 meters and can provide POE power for near-end equipment.

These network speed and speed products can realize network access of network terminals through combination or separate use, which can be well applied in the field of security monitoring, and also has the following various performance characteristics:

a) The data bandwidth is large, the data forwarding speed is fast, and the real-time performance is strong;

b) The transmission distance is far: the transmission of the network switch can reach 150 meters of the network cable;

c) Stronger environmental compatibility:

The climate environment is compatible: -2575 ° C, basically adapt to the cold and hot climate in the north and south.

Electromagnetic compatibility: 4KV6KV lightning protection, static electricity protection, and ground potential difference isolation function, reflecting the good electromagnetic compatibility of the product.

d) Reliable network and power management capabilities:

In order to ensure the stable operation of the product in the outdoor environment, the switch adopts a fanless system and is equipped with redundant power supply to ensure the reliability and stability of the product. The continuous working time of the product reaches more than 50000hs, far exceeding the working level of ordinary exchange. .

e) Conducive to the choice of transmission cable, which is conducive to installation and maintenance.

Various installation methods include: rail mounting, upper wall mounting and other installation methods to meet the needs of product installation under different conditions.

f) cost-effective

The product has high cost performance and is specially designed for security monitoring applications. The product index is close to the industrial level, and the price of the product is similar to that of the ordinary network product.

2) Network aggregation switch: The aggregation switch is the network convergence point of each access switch. Compared with the common commercial aggregation switch, the security aggregation switch requires less management functions. In addition to providing sufficient bandwidth for each bandwidth, Vlan and other functions are required to classify and manage each monitoring point. The monitoring network is often used as a stand-alone system, and the aggregation switch implements the aggregation of the access switches, usually located in the corresponding monitoring center, for video storage, wall loading and analysis, etc., and also provides for the monitoring center or workstation of the superior level. Monitor video data. Such switches are less adaptable to the environment due to their use in the monitoring center, but the various performances are suitable for various applications for security monitoring: in general, the following features are included:

a) Provide 100/1000M network bandwidth and ample data exchange convergence buffer.

b) Stronger environmental compatibility: anti-surge protection and ground potential difference isolation protection, and electrostatic protection are required.

c) Reliable network and power management capabilities. Redundant power supply and long-term continuous working capacity, generally above 50,000hs.

d) Conducive to installation and maintenance.

e) Reasonable cost (high cost performance). According to the special design of the security industry application, the video data forwarding speed and bandwidth are enhanced, and some network management functions that are not used are deleted, so the product is cost-effective.

f) Compatible with electrical and optical ports, modular. In order to adapt to different access modes of the access switch, it is compatible with optical ports and electrical ports, and adopts modularization. According to different access, optical ports and electrical ports are selected.

3) Network core switch: In the security system, the core switch is a switch for various network switches, network storage, data analysis, data security and other service management, usually with 3-layer network management capabilities. Different services in the security system, although there are distributed network data processing designs, sometimes the core switches are also compatible with massive data exchange management services such as data aggregation, that is, the core switches still need strong data exchange processing and management capabilities to meet the smooth flow of data links. , data security, data redundancy and other requirements.

At the same time, the network system also has network routers, firewalls, or network switches related to services. For example, there are data aggregation functions in the security monitoring, and optimized network aggregation multi-service processing switches for data storage, video decoding on the wall, video analysis and data backup services. In a distributed layout, such devices are generally more cost-effective, simple to manage, and are particularly required by small and medium-sized network monitoring systems.

2. Common networking structure types

The network structure is a very important issue for engineers and engineering designers. According to the actual situation of security engineering, the structure of network monitoring mainly includes:

1) Star topology: It means that each workstation is connected to the network in a star-shaped manner. The network has a central node, and other nodes (workstations, servers) are directly connected to the central node. This structure is centered on the central node, so it is also called a centralized network. It has the following characteristics: simple structure, easy to manage; simple control, easy to build a network; network delay time is small, transmission error is low. But the shortcomings are also obvious: high cost, low reliability, and poor resource sharing. The main advantages of the star topology are: easy management and maintenance, flexible reconfiguration, and easy fault detection and isolation.

2) Bus (chain type) topology: It means that each workstation and server are hung on a bus. Each workstation has equal status and no central node control. The information on the common bus is serially transmitted in the form of baseband. It spreads from the node that sends the information to both ends, just like the information transmitted by the broadcasting station, so it is also called the broadcast computer network. Each node performs an address check when accepting information to see if it matches its own workstation address, and if it matches, it receives the information on the network. The network characteristics of the bus topology are as follows: simple structure and good expandability. When you need to add a node, you only need to add a branch interface on the bus to connect with the branch node. When the bus load is not allowed, you can also expand the bus. The cable is used less and the installation is easy. The equipment used is relatively simple and reliable. high;

3) Ring topology: A closed loop is formed by a common cable, each node is directly connected to the ring, and information is transmitted from one node to another along a certain direction along the ring. The structural features are as follows: the cable length is short, and only the nodes need to be connected one after another. All sites have fair access to other parts of the network and network performance is stable. The disadvantage is that the node failure will cause the whole network failure, because the data transmission needs to pass through every node on the ring, such as a node failure, causing the whole network failure. The joining and withdrawing process of nodes is complicated. The medium access control protocol uses token passing, and the channel utilization is relatively low when the load is very light.

4) Hybrid model: According to the above topology, tree, mesh, tangent ring and honeycomb topologies can be formed. We can choose these models according to the actual situation.

In the telecommunications network and the INTERNET network, all networks are connected to the Internet. Typically, the network can be further divided into three layers: an access layer, a convergence layer, and a core layer (backbone layer). The part of the network that directly connects to the user or accesses the network is called the access layer, and the part between the access layer and the core layer is called the distribution layer or the aggregation layer. The access layer is designed to allow the end user to connect to the network. Therefore, the access layer switch has low cost and high port density characteristics; the aggregation layer switching layer is the convergence point of multiple access layer switches, and it must be able to handle all traffic from the access layer device and provide uplink to the core layer. The link, therefore, the aggregation layer switch requires higher performance, fewer interfaces, and higher switching rates than the access layer switch. The core part of the network is called the core layer. The main purpose of the core layer is to provide optimized and reliable backbone transmission structure through high-speed forwarding communication. Therefore, the core layer switch should have higher reliability, performance and throughput.

The massive real-time data in the security video surveillance system has higher requirements for the entire network, which promotes distributed storage. In the system, not all data is aggregated to the core layer for storage and forwarding, but is distributed and processed after distributed storage processing. According to the characteristics of China's security video surveillance, Utopu Electric Express has made a more optimized subdivision. The system is divided into a transmission access layer, an access aggregation layer, and an aggregation service layer and a core layer. The transmission access layer is designed to solve the complex EPOC\EVOC\EOC cable transmission, optical fiber transmission, EP, POE and other rich transmission access methods in complex environments, taking into account the difficulty of deployment and cost. The access aggregation layer will focus on the solution of both existing access and aggregation. The POE switch is a typical product. This product has both POE access and aggregation functions. In actual engineering, it can directly access the network terminal. There is a higher level that can be directly aggregated to the aggregation business layer, and it can also meet the requirements of local storage. The aggregation service layer mainly implements data storage, video wall, video analysis, data backup and other services in security monitoring to meet the requirements of security monitoring and multi-service. The core layer is designed to focus on network management and data processing services for security video surveillance systems, access control intercom systems, broadcast systems, and external networks.

Third, it is conducive to adapt to the scene

Why is the security monitoring system unstable with ordinary household switches? In addition to the ordinary household switch, there is no excessive requirement for network data traffic. The uplink port usually does not exceed 100M, and the traffic is small. It cannot meet the strict requirements of security monitoring for real-time, integrity and fluency of large-traffic video synchronization. It is unable to meet the requirements of the complex and varied application environment of security monitoring. If it is similar to ordinary home security monitoring, which is not demanding for business, it can also adopt a family-type switch, but it rises to a public security monitoring system such as community security, safe city, and safe campus, and a switch for home or general enterprise. Can't use it anymore.

1, reliability

There are many indicators for measuring reliability, usually with reliability R(t), also known as mean time between failure (MTBF), mean time to repair MTTR, and failure rate λ(t). We use MTBF indicators to analyze, the average time between failures (MTBF) requirements of household switch systems are generally not high, generally ranging from 1, 2 years, some even do not explicitly require, while network monitoring requires at least 3 years, some A complex environment or a demanding environment usually lasts for more than a few decades. Since the home system is small, the cost of replacing a device is low and the impact is small. In the security monitoring project, the reliability is low and the reliability of the whole system is lower. This not only affects the monitoring business, but also greatly increases the system maintenance cost for the engineering company, and some even cannot accept the inspection, causing serious losses. Therefore, in terms of reliability, there is a great difference between ordinary switches and security dedicated switches.

2. Climate environment compatible

In view of the equipment's ability to adapt to the climatic environment, GB/T2423 national standards have clear specifications for temperature, humidity, climate and other indicators. Due to the complex climatic environment of security monitoring equipment, especially front-end camera and access transmission equipment, the equipment has high requirements for high and low temperature, high humidity protection, corrosion resistance, aging resistance and air pressure. As far as high and low temperature indicators are concerned, household switches or general enterprise-class switches usually only require indoor conditions under a temperature environment of 0-40 ° C. In the south, security monitoring equipment is required to work in an environment with an outdoor temperature of 55 ° C or above and a closed signal box. In the north, it is also required to work normally in a low temperature -20 ° C, or even -40 ° C low temperature outdoor, corridor and other environments. If you use a home switch or a common enterprise switch to replace these environments, even if you can work, there will be crashes, packet loss, etc., resulting in unstable operation of monitoring video, image discontinuity, video interruption, etc. Monitoring requirements are not met at all. Different security monitoring environments have higher requirements for high humidity protection, corrosion resistance and aging resistance, air pressure, etc., and these have no special requirements for ordinary switches.

3, mechanical environment compatible

In the security monitoring system of locomotive sports environment such as automobile and rail transit, the network switch requires the ability to be compatible with the mechanical environment. The national standard GB/T2423 has high requirements for mechanical shock, collision, free fall, vibration and other indicators of equipment. This is also not required for a normal network switch.

4. Electromagnetic environment compatibility (EMC)

Because the security monitoring equipment needs to work under the electromagnetic field work of different environmental environments including communities, factories, power stations, and locomotives. In particular, the electromagnetic immunity (EMS) of the equipment has higher requirements. These include electrostatic immunity (ESD), radio frequency electromagnetic field immunity (RS), electrical fast transient burst immunity (EFT), and surge (shock) immunity as specified in national standard GB17626 (Surge) ), radio frequency field induced conduction disturbance immunity (CS) and other projects. Ordinary equipment is at level 1 or not required. These security monitoring devices are usually required to be above level 2 and level 3. The higher the anti-interference ability of the equipment, the more stable the equipment works. The equipment is low in immunity and the equipment is unstable. Equipment reset, high packet loss rate, low equipment life, and even equipment burnout can occur. The specific performance is the phenomenon of image pause, flower screen and even system smashing.

5, safety regulations

Security monitoring equipment needs to consider the safety of installation and use in power plants, coal mines, gas stations and other projects. Due to the small space of many industrial field installation equipment, construction and maintenance personnel can easily directly access the power supply part of the network equipment, and reasonable voltage provides an important guarantee for the safety of the operator. Equipment also needs to consider measures such as flame retardant to meet engineering fire protection requirements. In addition to this national standard GB4943 for electric shock, fire, in different environments, it also has comprehensive specifications and requirements for heat hazards and mechanical hazards. Although ordinary switches have requirements for safety, electric shock, fire protection, etc., they are different from the requirements of the industrial environment.

6, quality

The switches for network monitoring usually adopt international large-scale and mature industrial grade chips, high-performance and high-stability industrial-grade CPUs, industrial-grade power solutions, and durable and durable casings. Industrial-grade product production and quality management systems are adopted to ensure product quality assurance. Ordinary household switches, because of the cost, usually choose the chip and material aspects and production processes do not need to be so elegant.

Fourth, it is conducive to engineering installation and maintenance

Most of the monitoring systems take into account the requirements of safety and stability. Cables are usually used to transmit signals. The wiring and equipment installation directly affect the formation of the monitoring system. The main factors affecting cable layout and construction are:

1: Business category: Different environments and services vary widely. Generally, power, coal mines, factories, border defenses, and road monitoring are much more compatible with the environment of the entire system, and the installation difficulty and requirements are high. Differences in customer requirements may also be unusual for on-site engineering installations. The location of the equipment also determines the requirements of the equipment for the climatic environment, such as high and low temperature, humidity, etc., must be considered. Regardless of the impact of environmental compatibility requirements such as lightning protection and anti-jamming on equipment selection, it also brings more risks.

2: System layout: The existing engineering construction environment and building structure have a direct impact on the system layout. The layout can usually be reasonably adopted star, bus, ring or hybrid topology. At the same time, we must also consider the transmission distance, transmission cable selection, layout space, construction difficulty, construction period and materials and labor costs. Different construction teams are good at different, some are good at cable equipment, and some are better at cable routing. The EOC, EPOC, EVOC, EP and other products of UTECH's electric speed combination provide more options for system cable layout, combining optical transmission and electric transmission.

3: Equipment installation and commissioning: After the system layout is determined, the security location of the equipment is basically determined. Whether it is conducive to installation and commissioning is also critical. Some companies do not have the low cost of the product, and even the basic fixed methods are not, let alone how to optimize the line and maintenance. Youtpu network electric speed joint products have wall, rail, MIT rack 19# rack and other installation methods, which provide more convenience for system installation and provide guarantee for project acceptance. In addition to the installation, the commissioning and commissioning personnel may be considered for different workers. The high-altitude operation not only affects the cost but also the requirements of the personnel. Convenient debugging or remote commissioning management will save a lot of labor costs.

It can be seen that in addition to focusing on product function and performance, our products are also very important for the installation and commissioning of the product itself.

summary

After the above analysis, what kind of network transmission products do we need to be clearer, we think it is mainly "four more."

1, the technology is more professional:

For security professional application design, in the "throughput, delay, packet loss rate, back-to-back" and other indicators to meet the multi-stream HD video data transmission and convergence and other comprehensive applications. High-power reliability POE power management technology reduces access equipment, cabling and engineering maintenance costs. It satisfies services such as data access, data storage, video data analysis and processing, data backup, and data uploading.

2, the performance is more reliable:

Products must be built to industrial quality, more powerful electromagnetic compatibility, environmental compatibility, outdoor equipment; meet low temperature -40 degrees, high temperature 75 degrees large temperature difference environment; higher safety and other aspects; strong adaptability to humidity; strong dustproof , there is a fan system ... fanless system, can work in a closed environment.

3. The networking is more scientific:

The product networking is scientific and efficient, and is designed by sub-access layer, aggregation layer and core layer architecture. In the access layer, it can satisfy the star topology, bus topology, ring topology and hybrid topology model to meet the access of other security network monitoring devices in different environments. Access layer: There are abundant access devices to meet the requirements of different environments in security. Rich selection of transmission media: coaxial cable, network cable, twisted pair, fiber transmission access network. Network speed and speed to solve the power supply problem. Convergence layer: It needs to solve data access and application data management such as network access and data distributed storage and data backup. Core layer: Address WAN, data security, network management.

4, the installation is simpler:

The product requires easy installation and maintenance, such as wall mounting, rail mounting, rack mounting and desktop placement. It can be installed indoors, or installed in the corridor, under the eaves, outdoor waterproof box, etc. It is easier to install and more convenient for future maintenance.

Intelligent, digital and networked are the inevitable trends in the development of video surveillance. The emergence of intelligent video surveillance is the direct manifestation of this trend. Although the security monitoring system has gradually approached the traditional network system, but after all, it has its specific industry attributes. At present, most of the network transmission products we can choose are traditional products of industry giants such as Cisco and H3C, although these giants are super strong. The technical force to make products, but in the specific market segment, it is not necessarily the area they focus on. Youtepu.com is currently focusing on the most research and development strength of the market, from the Security Association. In the previous "100 City Meetings", we can all see that "Net Power Speed ​​Link" is doing free technology popularization and communication work. As the market in the industry continues to mature and the growth of local companies, we hope that one day we will see that our country's local enterprises, such as Yotech, and international giants such as Cisco and H3C can compete on the same stage, providing more choices for the majority of industry customers. Better product.

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