M-OTN/OSU is moving from technological standard innovation to commercial deployment stage

C114 Communication Network Shuiyi
C114 News on December 30th (Shui Yi) With the deployment of 5G, gigabit networks and other scales, it has accelerated the digital transformation of homes and enterprises. It is predicted that the traffic at edge sites will increase threefold in the next five years. In the era of computing power, new services such as 4K/8k and XR metaverse are also thriving, with exponential growth in access traffic. Operators' urban domain sites generally face the dilemma of insufficient bandwidth resources and insufficient room space and fiber resources during expansion.
In order to better meet the needs of future computing power network development, C114 held an online seminar on December 29th with the theme of "Exploring the Evolution Direction of Urban Optical Network in the Computing Power Era", inviting experts and scholars from all walks of life to conduct in-depth discussions on the evolution direction of urban optical network in the computing power era. Jing Ruiquan, a senior expert and professor level senior engineer in the transmission field of China Telecom, gave a detailed introduction to the development and application promotion of M-OTN/OSU technology in the past year.
OTN sinking, small particle business carrying distress problem
Jing Ruiquan stated that in the context of the suspension of SDH/MSTP construction, it has driven the OTN network to sink to the edge of the metropolitan area network. At the same time, a large number of high-value dedicated line services still maintain the small granularity attribute below GE. Taking Shanghai Telecom as an example, the average bandwidth of ordinary dedicated lines in small and medium-sized dedicated line services is currently less than 30Mb/s.
In addition, the OTN network sinks to the edge of the network, with a sharp increase in the number of nodes, which is very sensitive to equipment costs. Therefore, it is necessary to introduce more small manufacturers to reduce equipment costs. At the same time, there are many manufacturers of connected OTN devices, which require open decoupling of device control in order to achieve unified control and reduce maintenance costs.
In order to support efficient carrying of small particle businesses below GE, a packet enhanced OTN (VC&PKT) scheme has been introduced. However, the multi plane switching technology of packet enhanced OTN is complex, network management and operation are complex, and there are also challenges such as limited VC low order cross capacity and low QoS service aggregation ratio.
Jing Ruiquan stated that in response to business development needs and existing problems in the OTN network, China Telecom, in collaboration with various industry parties, has proposed an OSU based M-OTN technology innovation solution, with the goal of providing a low-cost, low latency, and low-power comprehensive business bearer solution mainly focused on urban applications.
M-OTN/OSU is an ideal solution with obvious advantages
M-OTN, also known as Metro optimized OTN, has three main characteristics: introducing flexible mapping optical service units (OSUs) to provide efficient carrying capacity for multi service granularity at 2Mbit/s -10Gbit/s; Introducing the new OTU0/25/50 OTN interface and reusing Ethernet optical modules to achieve low-cost networking for metropolitan access and aggregation layers; Introduce an open control interface to achieve unified control of multi vendor access type M-OTNs.
OSU is a hard pipeline technology for optimizing packet bearer, while also taking into account the bearer of TDM services; Support optimized OSU bandwidth lossless adjustment mechanism, which can achieve rapid adjustment; By reducing the mapping hierarchy and matching cell exchange, low latency transmission is achieved.
After elaborating on the characteristics of M-OTN and OSU technology, Jing Ruiquan summarized the outstanding advantages of M-OTN/OSU technology.
Multi service unified bearing: OSU can provide a unified bearing capacity of 2Mbit/s-10Gbit/s granularity for multiple services, gradually evolving from ODU, VC, and Ethernet to ODU/OSU unified bearing, simplifying service bearing solutions and network operation and maintenance.
Low latency: Compared with the current EooO bearer method commonly used in OTN networks, OSU achieves low latency transmission by simplifying mapping mechanisms and reducing processing levels. After testing, the RTD in the metropolitan area can be reduced by 1-3 seconds.
Bandwidth lossless adjustment: OSU supports bandwidth lossless adjustment in multi vendor networking scenarios. Compared to the existing ODUflex lossless bandwidth adjustment mechanism, OSU has shorter adjustment time and finer adjustment granularity, with a minimum adjustment step of 2.5M, a second level adjustment time, and an adjustment range of 2Mbit/s -10Gbit/s.
Ethernet business aggregation capability is strong: currently, the aggregation ratio of EOS business supports a maximum of 64:1, while the aggregation ratio of 10GE board cards for EoOSU business can reach 200:1100GE board cards with a aggregation ratio greater than 500:1.
Strong cross capability of small particle business: Currently, the OTN devices in the current network support 80G low order VC cross capacity and can provide 3225 10M EooO services; At present, the typical M-OTN device has an OSU crossover capacity of 6.4T and can provide 16000 EoOSU services, which is about 5 times that of the EooO method.
Standardization is being promoted in an orderly manner, with strong support for the industrial chain
Standardization is the soul and universal language in the field of information and communication. In terms of M-OTN/OSU technology standardization work, China Telecom Enterprise Standard: "Technical Requirements for Metropolitan Optical Transmission Network (M-OTN) Equipment Based on OSU01" has been released and implemented at the end of 2021.
In terms of industry standards, starting from December 2019, CCSA in China has established "Technical Requirements for Optical Business Units (OSUs)" and "Technical Requirements for OTN Equipment Based on OSUs" industry standards. Currently, the two industry standards have been submitted for consultation and are expected to be completed by the end of 2023. In terms of international standards, ITU-T initiated the G.osu standard in early 2020, updated the scope of the standard in September 2022, and is expected to be completed by December 2023.
Jing Ruiquan stated that both the industry standard and the ITU international standard have been postponed until the end of the 23rd year, but there are still significant differences in actual progress because the main technical solution of the industry standard is consistent with the telecommunications enterprise standard. Therefore, although it has not been officially released yet, it can be developed based on it.
At present, M-OTN/OSU technology has received strong support from the industry chain. Jing Ruiquan introduced that the access type M-OTN devices (M1&M2) have recently completed centralized procurement testing for over 10 manufacturers' devices. The main functions and performance meet the technical specifications, and the devices support control interfaces that meet industry standards. They will be deployed on the current network in 2023.
Core and aggregation layer M-OTN devices (M3&M4), some manufacturers can currently provide FPGA versions of devices and are currently undergoing network testing; Mainstream manufacturers will provide devices with ASIC chip versions in the first half of 2023.
In addition, in terms of OSU instruments, OPWILL currently has instruments that support testing of M-OTN/OSU; In terms of OSU chips, domestic companies have already provided OSU ASIC chips for M1 box devices.
Continuously evolving and accelerating towards commercial deployment phase
Jing Ruiquan introduced that the M-OTN/OSU network evolution goal is completed in three stages. The current network status is VC plane, PKT plane, and ODU plane. During the transition period, OSU will be introduced to replace PKT plane, and the final goal network is to replace VC plane as well. OSU plane and ODU plane will achieve unified support for small and medium-sized businesses, including government enterprise dedicated lines, high-quality cloud access dedicated lines/cloud interconnection, and VR/video services.
For the application scenario of M-OTN/OSU, Jing Ruiquan pointed out that it is mainly in urban OTN: it needs to support both ODUk and OSU cross capabilities, and the M-OTN device at the urban outlet multiplexes OSU into ODUk. For backbone OTN: Continue to use the existing OTN network and provide ODUk crossover capability.
As mentioned earlier, the access type M-OTN device has completed the relevant work and is about to be deployed to the current network. In the process of exploring how to introduce OSU into the core convergence layer of the metropolitan area, Jing Ruiquan pointed out that based on the current situation of OTN networks and drawing on the experience of IP networks, two network building models, Overlay and Underlay, are currently being considered.
Jing Ruiquan introduced that China Telecom is currently conducting M-OTN/OSU network testing to verify the current network scale deployment capability and long-term operational stability of M-OTN/OSU technology, and to verify the ability of existing network equipment and network management system upgrades to support OSU. The current network testing equipment is all commercial M-OTN devices, and two OSU introduction modes, namely new construction and current network upgrade, are verified.
It is worth mentioning that China Telecom is currently researching an OTN based computing power network architecture. Jing Ruiquan introduced that M-OTN/OSU can be used to carry north-south traffic (from computing power users to computing power centers) characterized by small bandwidth, low latency, flexible scheduling, and on-demand services (BoD); For east-west traffic (between computing centers) that requires large bandwidth and low latency, OTN/WDM is needed to carry it.
Jing Ruiquan stated that after three years of continuous development and improvement, the domestic M-OTN/OSU technical standards have become mature and stable, and the industrial chain has been relatively complete, moving from technological standard innovation to commercial deployment stage. China Telecom will collaborate with upstream and downstream parties in the M-OTN/OSU industry chain to create a more complete ecosystem, actively promote the deployment and application of existing networks, and improve the business carrying capacity and customer experience of OTN networks.
Reprint: https://www.c114.com.cn/news/117/a1220497.html