Fixed networks have the advantages of large bandwidth, low latency, high stability, and flexibility, and can provide high-quality network services, so they have been widely used. However, in the development of fixed networks, there has never been a generational division of technology, which limits the development of fixed network technology to a certain extent.
We divide the development course of the fixed network into 5 stages according to the characteristics of different development stages. At present, the fixed network is entering the fifth-generation fixed network era (F5G), the F5G Development.
The collaboration of wireless networks and fixed networks can provide better performance and user experience. Compared with wireless networks, fixed networks can provide greater bandwidth and higher availability.
The expansion of wireless networks needs to rely on fixed networks. Optical fiber is the best connection medium for wireless base stations. Mobile network services with large bandwidth, wide coverage, and low latency need to be accessed and carried by optical fiber.
F5G can improve communication speed and user experience, provide gigabit access, ensure latency and reliability, and realize fiber-to-the-everywhere-and-everything (FTTE, Fiber-To-The-Everywhere-and-Everything).
The key problem that the current fixed network urgently needs to solve is how to realize large-scale networking and management based on higher speed and more flexible optical transmission technology.
Fixed networks from F1G to F5G development
The development stage of the fixed network since the 19th century, the fixed network has been developed for more than 100 years. Similar to the era division in wireless networks, according to the technical characteristics of fixed networks in different periods, the development process can also be divided into 5 stages.
The first generation of fixed networks was the telephone network.
This period lasted from the birth of the telephone network to the end of the 20th century, which lasted more than a century. During this period, the speed of dial-up access and ISDN development was very slow, and only audio services and dial-up calls could be supported.
At this stage, a relatively complete telephone network infrastructure has been formed, and its network architecture and control signals can be well adapted to the global network, which marks the beginning of the globalization of telecommunications.
The second generation of fixed networks is the era of broadband.
The period from the end of the 20th century to the beginning of the 21st century, with the promotion of the Internet and ADSL technology, fixed networks entered a period of rapid development, and the broadband era officially began. The popularity of personal computers and browsers has promoted the rapid development of the Internet, and the application of fixed networks has expanded from telephones to e-mails, search engines, and web browsing.
The third-generation fixed network is the next-generation access network (NGA) era, which is jointly promoted by the Internet and broadband networks.
Since 2005, operators have provided services based on broadband networks, and the fixed network services and network architecture have undergone tremendous changes. Because the traditional ADSL technology and the original telephone network architecture cannot support broadband services, VDSL technology is introduced. In the 1970s, optical fiber communication technology appeared and was first applied in the access network to realize the FTTx network architecture.
The hallmarks of the fourth-generation fixed network are 4K HD and fiber optic broadband.
Around 2010, an optical fiber replaced copper cable, optical broadband access technologies such as GPON developed rapidly. In 2012, the emergence of 4K high-definition signals requires a broadband network of no less than 100Mbit/s.
Because the optical access network has the advantages of high bandwidth, stability, simplified structure, and long-term development, it has attracted the attention of operators, and the fourth-generation fixed network construction has been fully launched, which has promoted the development of global optical fiber networks.
The fifth-generation fixed network requires the uplink and downlink speed to reach gigabit and above, and the delay is reduced to below 100μs.
F5G is the first to enter the domestic market, and its main business applications include high-definition video communications and VR services based on Gigabit networks. Its gigabit access capability can not only be used in homes, but can also be extended to various industries, such as enterprises, banks, and industries. Compared with the fourth generation, the fifth-generation optical fiber has a 10-fold increase in bandwidth and has the advantages of ultra-high reliability and ultra-low delay, which can realize the digital transformation of the industry.
Main features of F5G
The main features of F5G There are three main features of F5G, eFBB, Enhanced Fixed BroadBand, FFC, Full-Fiber Connection, and GRE, Guaranteed Reliable Experience, as shown in the figure.
Enhanced Fixed BroadBand (eFBB)
eFBB supports high-speed, large-capacity communications and high spectrum efficiency business requirements. Compared with F4G optical fiber bandwidth, the optical fiber access technology represented by 10GPON has increased the bandwidth of F5G by more than 10 times, and the network bandwidth has the ability to uplink and downlink symmetrical gigabit broadband.
Wi-Fi6 technology provides a gigabit connection, and users can connect to the data center and enjoy a high-bandwidth experience. Fully deploy 200Gbit/s and 400Gbit/s single-wavelength OTN, widely use C-band and L-band, continuously improve OTN capacity, and achieve high-performance transmission of more than 40Tbit/s on a single fiber. OTN is responsible for data center interconnection and even provides high-speed connections between servers in the data center.
Full-Fiber Connection (FFC)
FFC supports the business needs of high-coverage connectivity expansion and high-volume intensive communication. F5G uses a fully covered fiber optic infrastructure to support ubiquitous connections. The service scene has been expanded, the number of connections has increased by more than 100 times, and the era of full-fiber connections has been realized.
In the field of business services, OTN reduces the granularity of containers, provides connections as small as 2Mbit/s, guides the migration direction of MSTP services, solves the quality weaknesses of traditional Ethernet, VPN, and SD-WAN private line services, and can provide high-quality Dedicated line service.
In many different scenarios, when transitioning to a full-fiber connection, the number of network aggregation points required can be reduced, reducing the number of actual central offices (CO, center office) and simplifying the network for operators. The boundary between access and transmission will become blurred, and F5G is expected to achieve closer coordination between the two layers.
Guaranteed Reliable Experience (GRE)
GRE supports the business requirements of low-latency, high-reliability, and high-availability communication, and high operational efficiency. The network relies on the unique high-quality transmission capability of optical fiber, supports nearly zero packet loss, microsecond delay, and jitter, and cooperates with intelligent operation and maintenance supported by artificial intelligence and big data to meet the needs of users for the ultimate service experience.
Especially for high-bandwidth, delay-sensitive, and packet loss-sensitive services, such as high-definition video, cloud VR, and cloud gaming, millisecond-level low-latency transmission is required on OTN, PON, and Wi-Fi, and intelligent real-time service identification and high-speed quality network resource allocation.
Private line services and other industry application services require stable and reliable bandwidth, millisecond latency, and high availability to support SLA commitments, and networks need to have flexible E2E capacity reservation and isolation capabilities.
Mobile bearer services also require high bandwidth, millisecond-level low latency, high-reliability networking, and high-precision clock synchronization technology to ensure the quality of various mobile broadband services.
Typical application scenarios Because optical networks have the advantages of fast transmission speed and long transmission distance, in order to support the three features of F5G, it is necessary to use all-optical networks for service bearing. F5G can support and promote some emerging application scenarios, including cloud VR, cloud enterprises, online games, online medical care, and smart factories.
Three typical F5G application scenarios are introduced below.
Cloud VR
Independent channel cloud VR transmission. Cloud VR is the introduction of cloud computing and cloud rendering technology into VR services. VR services are sensitive to network indicators such as bandwidth, delay, and packet loss rate. Cloud VR encodes and compresses video and audio in the cloud, and then transmits them to the user terminal through a high-speed and reliable network. The user does not need to have high-performance rendering equipment locally.
To ensure a good VR experience, VR traffic needs to be transmitted through a dedicated VR service channel, so service identification is required. The backbone network is also transmitted through a dedicated VR service channel.
High-quality dedicated line
For some industries or departments with special needs, special line services need to be provided. For the securities and futures industries, in order to ensure the continuity of transaction work, it is necessary to have dual-line redundancy from the business hall to the headquarters; for medical institutions, services such as telemedicine and mobile medical treatment are required, and a large amount of medical image and other data needs to be uploaded and downloaded, A stable high-bandwidth dedicated line is required; with the digital development of enterprises, enterprises have put forward higher requirements for cloud-based dedicated lines.
Cloud dedicated lines need to have functions such as bandwidth guarantee, low latency, high link availability, flexible access, and efficient management and control.
Broadband application in the residential scene
In residences, typical applications of broadband networks include online education, online games, online meetings, and so on. Through the use of broadband network components to identify some high-demand bandwidth applications, and provide high-quality network resources between the terminal and the cloud for these services to improve user experience. All components and network resources are from end to end. The end control plane is managed in a unified manner.
F5G challenges and key technologies with the development of fixed networks, the future network form must be an end-to-end large-scale all-optical network featuring massive connections and ultra-large bandwidth. In order to ensure the ultimate user experience and realize network intelligence, existing technologies cannot support the core requirements of F5G, and key technologies at different levels are in urgent need of innovation.
Among them, the new generation pipeline agreement is particularly important.
In the era of F5G and even F6G, in the scenario of millions of connections, high dynamic concurrency of services is an important feature, which leads to a series of problems such as service orchestration, fast route construction and demolition, and service concurrency reconstruction; to ensure the ultimate user experience, Need to realize business perception, deterministic network, optical network security, etc.;
At the same time, data transmission and access technologies also need to be upgraded and innovated. In view of different levels of technical requirements, the key technologies in F5G can be divided into service protocol layer, pipeline protocol layer, and data transmission layer.
The key technology of data transmission layer
At the data transmission layer, in response to the operational problems caused by the continuous growth of business traffic and network bandwidth, high-speed line transmission technologies such as 200G/400G/800G further increase network capacity and reduce optical transmission cost per bit and power consumption on the basis of 100G. The main means are Including increasing the line baud rate, using high-order modulation and multiple sub-carriers.
Traditional Optical Transport Network (OTN) adopts optical layer wavelength division multiplexing and electrical layer time-division multiplexing, which has the advantages of large capacity and long distance. With the rapid growth of the number of users and the number of services, traditional OTN bandwidth has a large granularity, and it is difficult to achieve flexible bandwidth adjustment. In response to this problem, OSU flexible pipeline technology is proposed. While maintaining the ultra-low latency and ultra-high reliability of OTN, it further realizes the ability of ultra-small bandwidth granularity (2Mbit/s) and on-demand step-less and lossless bandwidth adjustment, up to 100% bandwidth utilization.
10GPON and Wi-Fi6 are representative technologies of F5G. With the improvement of network performance requirements, the current GPON technology is difficult to achieve future high bandwidth requirements. In response to this problem, 10GPON technology can provide sufficient bandwidth to improve the splitting ratio and transmission distance.
Existing Wi-Fi technology is difficult to meet the current requirements of high speed, low latency, large capacity, security, and energy-saving. In response to this problem, Wi-Fi6 technology mainly uses OFDMA, MU-MIMO, and other technologies, which can improve spectrum efficiency and throughput under dense user conditions, and can communicate with up to 8 devices at the same time.
While the speed and distance of optical network communication have been improved in an all-around way, the weak protection of optical fiber and the increasingly mature technology of optical fiber eavesdropping have made optical fiber communication security issues increasingly prominent.
In view of the complex key management, unprotected line overhead, and complex configuration and maintenance in traditional secure transmission, the endogenous security technology for wavelength division and access optical can achieve the advantages of zero key management, full signal protection, and zero-configuration, ensuring users End-to-end secure and reliable transmission.
Key Technology of Pipeline Protocol Layer
At the pipe protocol layer, the number of connections and the number of network elements in F5G is huge. The current routing strategy is difficult to achieve full utilization of network resources and fast routing. In response to this problem, the author proposes a lightweight routing protocol for mass connections.
One idea is to combine the ideas of SDN and segment routing (SR, Segment Routing), which is different from the processing of network topology information by all nodes in traditional routing protocols. It combines centralized and distributed methods. Some nodes have the function of identification, thereby avoiding Due to the instability caused by network fluctuations, it is suitable for large-scale networking scenarios.
In F5G, the OSU transmission granularity becomes smaller, the number of services that can be carried by a single fiber has increased significantly, and a single fiber break has an impact on a large number of services.
OSU technology divides ODU into smaller granularity, which increases the number of connections by more than 10 times.
F5G has diversified devices and levels and divides the network into logically independent virtual networks, that is, network slices. Use network slicing to transmit different services, isolate different slices from each other, realize on-demand allocation of network resources, and adapt the pipeline to different business requirements.
Key technologies of the business protocol layer
At the business protocol layer, in order to ensure the quality of service, transmission, computing, and storage resources need to work together. The segmented management of various cloud computing platforms makes collaborative control of resources difficult, and it is difficult to realize intelligent scheduling and optimal deployment of network resources. How to construct a network intelligent collaborative control system oriented to computing and transmission resources is a key issue to realizing the optimization of network resource efficiency.
Research the mechanism of multi-dimensional network resource virtualization and unified measurement methods, explore resource integration-oriented network resource collaborative control schemes, and realize intelligent collaborative control of resources in and between clouds.
In order to meet the differentiated requirements of different services, the physical network needs to be divided into multiple logically independent virtual networks. Different services need to be isolated from each other and be able to operate and maintain independently to meet reliability requirements. How to realize the on-demand distribution of network slices and realize end-to-end secure bearer is a key issue in realizing network service quality assurance.
Research the reliable control and management scheme of network slicing, establish an application-driven slicing end-to-end security risk assessment model, explore the interaction of security risks between different types of slices, and realize the security isolation of network slicing.
One of the core requirements of 5G is to realize the end-to-end deployment of services, using lightweight end-to-end service management orchestration technology.
Future development trends F5G will face development opportunities including related end-side equipment upgrades, infrastructure construction, and industry standardization promotion.
F5G can help Fnetlink all things, support more new application scenarios, such as smart factories, smart education, smart cities, etc., realize the connection of thousands of devices, and the microsecond transmission of massive data. F5G can be applied to scenarios with large bandwidth, low latency, and high security, and 5G can be applied to scenarios with high mobility and multiple connections.
F5G and 5G complement each other in different application scenarios. F5G can not only serve as a support in the 5G transmission network, but also cooperate with 5G to meet the needs of different industries for the integration of fixed and mobile networks, greatly improve user experience, promote the digital transformation of the industry, and promote high-quality social and economic growth.
At the same time, the development of F5G also faces many challenges, which are specifically manifested in the following aspects.
First is the high cost of the network.
The feature of F5G’s large bandwidth requires a large number of new sites, and equipment upgrades from sites, access, convergence to the core computer room are required to broaden the end-to-end pipeline; the feature of low latency requires adjustments to the network architecture, cloud computing power, applications, etc. It needs to sink to the access, convergence, core, and other computer rooms and user terminals to form distributed edge nodes.
The second is the low efficiency of operation and maintenance.
The traditional operation and maintenance model relies on user complaints, on-site repairs, and manual experience for fault location and processing. For scenarios with a large number of devices and wide connections, it is necessary to visualize network resources, perform network awareness, realize an active operation and maintenance mode, and complete intelligent fault prediction, fault location, and fault handling.
The third is the difficulty of all-optical connection.
In order to realize the all-optical connection, fiber to the desktop and machines, etc., it is necessary to upgrade the optical terminal, optical access, and optical transmission on the basis of existing facilities, so as to bring intelligence and ultra-broadband to individuals, families, and enterprises. , High-speed all-optical network.
Fourth, industry recognition is slow.
Involving new network architectures, new technical solutions, etc., it is necessary to complete the layout of intellectual property rights in advance; a series of key technological research, there is a huge academic innovation space; industry recognition requires a series of international/national standard formulation and the gradual formation of the industrial chain, and the process is slow.
At this stage, the fixed network has entered the F5G era, and business demands on the network are getting higher and higher. In view of the development direction of F5G, large-scale, multi-granularity networking must be the core feature of the future network architecture, which brings about transmission control problems at different levels.
Aiming at the core requirements of F5G, this article analyzes the deficiencies of existing technologies and summarizes the key technical requirements at the data transmission level, pipeline protocol level, and service protocol level. Through the collaborative research of these technologies, it can meet the three major characteristics of F5G and the business needs of future F5G applications.