Accelerating new infrastructure construction: Single-wavelength 200G backbone network is about to emerge, how far is 400G?

While the new infrastructure is accelerating the deployment of 5G networks, it is also pushing operators’ backbone networks into the era of single-wavelength 200G. The backbone network is the “new infrastructure” in the new infrastructure.

It is understood that China Mobile recently announced the list of successful bidders for the centralized procurement of transmission equipment for the 13th phase of its inter-provincial backbone transmission network new construction project. Huawei Technologies Co., Ltd. and ZTE Corporation won the bids for the centralized procurement of WDM/OTN equipment boards and ports for the eastern and western regional planes respectively.

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It is worth noting that this is the first time that China Mobile has centralized procurement of a 200G OTN system at the provincial backbone network transmission level. It is also the first operator among the three major domestic operators to centralized procurement of this system. If all goes well, it will also be the first single-wavelength 200G backbone network in China after completion.

Although in 2019, China Telecom and China Unicom only carried out centralized procurement of 100G WDM/OTN equipment and continued to expand their single-wavelength 100G all-optical networks, the two operators have long conducted related tests on single-wavelength 200G and 400G backbone networks, and even carried out a small amount of centralized procurement. As the deployment of 5G networks accelerates, it is expected that the two operators will soon include super-100G backbone network OTN systems in their centralized procurement plans.

This means that the operator backbone network and the commercial use of 5G networks will simultaneously enter the single-wavelength 200G era.

Why build a new 200G backbone network?

The main reason for building a new single-wavelength 200G backbone network is that the existing backbone network bandwidth is difficult to meet the actual needs after large-scale commercial use of 5G in the future.

The three major operators have built a single-wavelength 100G backbone network and carried out several rounds of capacity expansion to meet the growing traffic demand.

According to data from the Ministry of Industry and Information Technology, mobile Internet access traffic consumption reached 122 billion GB in 2019, an increase of 71.6% over the previous year. As of the end of December last year, the number of Internet broadband access ports reached 916 million, of which fiber-optic access (FTTH/0) ports reached 836 million.

At present, the country is promoting the construction of new infrastructure, and 5G is one of the seven major areas of new infrastructure. The substantial increase in bandwidth demand, network flattening, and the interconnection of large central computer rooms and data centers in the 5G era will pose huge challenges to the backbone network. Some experts believe that the current single-wave 100G backbone network is difficult to meet the network bandwidth demand after 5G commercialization matures.

Wei Leping, executive deputy director of the Communications Technology Committee of the Ministry of Industry and Information Technology and director of the Technology Committee of China Telecom Corporation, predicts that China's backbone network capacity will exceed 1Pbps in 2020 and is expected to approach 1.4Pbps in 2022.

The expansion of the backbone network is not like turning on a light and using it right away. It requires operators to plan and build it in advance. Therefore, China Mobile launched the centralized procurement of the 200G OTN backbone network in early 2020.

It is worth noting that some experts pointed out that the backbone network is evolving towards 400G and 600G, and 1T equipment is expected to mature in 2021.

This is indeed the case. It is reported that since 2016, China Unicom, China Mobile and China Telecom have successively launched single-wavelength 400G system tests. Among them, China Unicom also launched the centralized procurement of G.654.E optical fiber cables suitable for 400G systems in 2018. This means that the 400G era will not be far away.

What are the backbone network industry chain companies?

Although OTN technology has become mainstream in backbone networks, OTN manufacturers are not the only ones involved in backbone network construction.

It is understood that China's Internet architecture mainly adopts a layered connection method, which is vertically divided into three levels: backbone network, metropolitan area network and access network. Among them, the backbone network is the top-level inter-provincial high-speed network. Basic telecommunications operators set up backbone nodes in provincial capitals and major cities, and set up direct links between nodes to form the backbone network.

After years of construction and development, there are currently seven backbone networks in the country, of which four are built and managed by the three major operators, namely China Telecom's CHINANET 163 and CN2, China Mobile's CMNET and China Unicom's China169.

The backbone network architectures of the three major operators are similar, mainly consisting of a core layer (core nodes) and a regional layer (aggregation nodes, access nodes). The core layer is mainly used to provide interconnection with the international Internet and to provide a channel for information exchange between regions. The regional layer mainly provides information exchange within the region and access to the backbone network. Communication between regions must pass through the core layer.

However, in recent years, operators have been pushing the backbone network architecture to evolve towards a flatter direction, increasing the number of core nodes, reducing the number of access nodes, allowing more large urban metropolitan area networks to directly access the backbone network, reducing routing nodes, and making information transmission simpler and more efficient.

Whether it is a core node or an access node, several routers and switches will be set up. These nodes are interconnected through OTN equipment and all-optical networks, and use BGP, IS-IS and other protocols for information transmission.

Through the analysis of operators' centralized procurement and bidding in recent years, the main network elements for building a backbone network are OTN equipment, routers, switches, optical fiber cables, etc. Other network elements include DRA equipment, optical protection systems, quality monitoring systems, network management systems, security protection systems, as well as engineering design, engineering construction, and engineering supervision services.

In summary, the main OTN equipment manufacturers are Huawei, ZTE, Fiberhome and Shanghai Nokia Bell. Huawei is the supplier of core routers, Huawei, ZTE, H3C and other high-end router suppliers, Huawei, Ruijie Network and other high-end switch suppliers, Changfei Optical Fiber, Fiberhome, Hengtong Optics, Zhongtian Technology, Hangzhou Futong, Tongding Interconnect and other optical fiber and cable suppliers, Accelink Technologies, Bannard Communications, Jiexin Technology and other optical device suppliers, Huawei and ZTE are the main suppliers of DRA equipment, Accelink Technologies, Bannard Communications, Jiexin Technology and other suppliers of OLP equipment, optical line protection boards, dispersion compensation units, fiber amplifiers, cables, and optical attenuators are Accelink Technologies, Bannard Communications, Jiexin Technology and other suppliers, and Huawei, Hangzhou Deep, Beijing Shenzhou Green Alliance and other DDOS protection equipment suppliers. In addition, there are a large number of backbone network engineering design, construction, and supervision service providers.

How far is the evolution to 400G?

The industry has always called for the construction of 400G backbone networks, and it was predicted that this demand would appear around 2020, but it has not been realized due to cost reasons. Now China Mobile plans to build a new 200G backbone network, but it has also reserved space for the evolution to 400G in centralized procurement. It is reported that Huawei and ZTE's related products and solutions support 200G, 400G, and 1T transmission rates.

The biggest obstacle to the evolution to beyond 100G is the transmission distance without relays. In the context of the general compression of capital expenditures, operators hope to increase the optical transmission rate while ensuring longer transmission distances and reduce the deployment of electrical relay sites to reduce the construction costs of backbone networks. Huawei said that its OTN products are based on the industry-leading Super 200G technology and can achieve up to 5,000 kilometers of transmission without electrical relays; ZTE supports 1,700 kilometers of transmission without electrical relays.

In addition to Huawei and ZTE, FiberHome and Shanghai Nokia Bell have previously won bids for the centralized procurement of 100G backbone network-related projects of the three major operators, but they were not selected for the centralized procurement of China Mobile's new 200G backbone network. This seems to mean that there is still a lot of room for improvement in the technical reserves for the evolution of the industrial chain towards super 100G.

It is worth noting that China Mobile only purchased WDM/OTN equipment boards and ports this time. However, building a 200G backbone network requires not only OTN equipment, but also other network elements such as routers and switches, especially optical fiber cables.

The general lifespan of optical fiber is 20 years. In order to meet the needs of 5G networks, operators must consider the network needs of the next 10 to 20 years when purchasing optical fiber cables. The focus of future network needs is 400G, or even 1T speeds, which means that operators need to deploy optical fiber cable products that support 200G and 400G systems in advance, such as G.654.E optical fiber.

It is understood that the total length of China Mobile's newly built backbone network is 105,900 kilometers. If one backbone network optical cable is 48 cores, then the number of optical fibers required to lay one optical cable is 5,083,200 core kilometers, but the actual purchase volume may be even more than this number.

Although the new backbone network cannot use all G.654.E optical fiber for cost considerations, and in most cases, it uses a hybrid cable of G.652.D and G.654.E optical fiber, the upcoming demand will also be a big order for optical fiber and cable manufacturers. After all, the total demand for backbone networks is not high. Previously, the G.654.E optical fiber procurement volume in the Hebei Mobile provincial backbone transmission network core-added ultra-low-loss G.654E optical cable framework project was only about 27,000 core kilometers; China Unicom conducted a second bidding for the construction of five provincial optical cable lines, including the Hunan section of the Beijing-Hankou-Guangzhou optical cable, and the demand for G.654.E optical cables and hybrid cables was only about 2,971 kilometers.

Currently, the manufacturers that can supply G.654.E optical fiber mainly include Changfei Optical Fiber, Hengtong Optics, FiberHome, Hangzhou Futong, etc. In fact, not only optical fiber and cable manufacturers, but also optical device, router, switch, and other network element manufacturers will benefit from the construction of 200G backbone network.

The construction of a single-wavelength 200G backbone network is imminent. This is an important step in the large-scale deployment of 5G. It is also a necessary upgrade of operators' fixed optical networks before the large-scale commercial use of 5G in the future, but it is not the end. Because with the gradual increase in 5G applications, after the Internet of Everything becomes possible, the evolution to 400G will be an inevitable choice for the backbone network. Considering that the backbone networks of the three major operators have completed the evolution to 100G in only 5 to 6 years, and now they are starting to build a 200G backbone network, it means that the 400G era may not be far away under the promotion of new infrastructure.