It is the backbone transmission network of the next generation. Simply put, it is a wavelength-based next-generation transport network.
OTN is a transport network based on wavelength division multiplexing technology that organizes the network at the optical layer, and is the backbone transport network of the next generation. OTN is a new generation of “digital transmission system” and “optical transmission system” regulated by a series of ITU-T recommendations such as G.872, G.709, and G.798. It will solve the problem of no wavelength/sub-wavelength services in traditional WDM networks. Problems such as poor scheduling capability, weak networking capability, and weak protection capability. OTN solves a series of several problems of traditional systems through a series of protocols.
OTN spans the traditional electrical domain (digital transmission) and optical domain (analog transmission), and is a unified standard for managing electrical and optical domains.
The basic object of OTN processing is wavelength-level business, which pushes the transport network to the stage of a true multi-wavelength optical network. Due to the combination of the advantages of optical domain and electrical domain processing, OTN can provide huge transmission capacity, completely transparent end-to-end wavelength/sub-wavelength connection and carrier-class protection, and is the optimal technology for transmitting broadband large-particle services.
main advantage
The main advantage of OTN is that it is fully backward compatible, it can build on the existing SONET/SDH management functions, it not only provides complete transparency of existing communication protocols, but also provides end-to-end connectivity and networking capabilities for WDM, It provides the specification of optical layer interconnection for ROADM, and supplements the sub-wavelength aggregation and grooming capabilities. The end-to-end link and networking capabilities are mainly established on the basis of SDH, and a model of the optical layer is provided.
The OTN concept covers the optical layer and the electrical layer network, and its technology inherits the dual advantages of SDH and WDM. The key technical features are as follows:
1. Various client signal encapsulation and transparent transmission The OTN frame structure based on ITU-TG.709 can support the mapping and transparent transmission of various client signals, such as SDH, ATM, Ethernet, etc. Standard encapsulation and transparent transmission can be achieved for SDH and ATM, but the support for Ethernet at different rates is different. ITU-TG.sup43 provides supplementary recommendations for 10GE services to achieve different degrees of transparent transmission, while for GE, 40GE, 100GE Ethernet, private network services Fibre Channel (FC) and access network services Gigabit Passive Optical Network (GPON) ), etc., the standardized mapping method to the OTN frame is currently under discussion.
2. Bandwidth multiplexing, crossover and configuration of large particles The electrical layer bandwidth particles defined by OTN are optical channel data units (O-DUk, k=0,1,2,3), namely ODUO(GE,1000M/S)ODU1 (2.5Gb/s), ODU2 (10Gb/s) and ODU3 (40Gb/s), the bandwidth granularity of the optical layer is wavelength, compared to the scheduling granularity of SDH VC-12/VC-4, OTN multiplexing, crossover and The configured particles are obviously much larger, which can significantly improve the adaptability and transmission efficiency of high-bandwidth data customer services.
3. Powerful overhead and maintenance management capabilities OTN provides overhead management capabilities similar to SDH, and the OTN frame structure of the OTN Optical Channel (OCh) layer greatly enhances the digital monitoring capabilities of this layer. In addition, OTN also provides a 6-layer nested serial connection monitoring (TCM) function, which makes it possible to perform end-to-end and multiple segment performance monitoring at the same time during OTN networking. Provides appropriate management means for cross-operator transmission.
4. Enhanced networking and protection capabilities Through the introduction of OTN frame structure, ODUk crossover and multi-dimensional reconfigurable optical add-drop multiplexer (ROADM), the networking capability of the optical transport network has been greatly enhanced, and the SDHVC-based 12/VC-4 scheduling bandwidth and the status quo of WDM point-to-point providing large-capacity transmission bandwidth. The adoption of forward error correction (FEC) technology significantly increases the distance of optical layer transmission. In addition, OTN will provide more flexible service protection functions based on electrical layer and optical layer, such as ODUk layer-based photonic network connection protection (SNCP) and shared ring network protection, optical layer-based optical channel or multiplex section protection, etc. But shared ring technology has not yet been standardized.
Post time: Nov-01-2022