OTN学习笔记

1、The optical transport hierarchy (OTH) supports the operation and management aspects of optical networks of various architectures, e.g., point-to-point, ring and mesh architectures.

This Recommendation defines the interfaces of the optical transport network to be used within and

between subnetworks of the optical network, in terms of:

–optical transport hierarchy (OTH);

–functionality of the overhead in support of multi-wavelength optical networks;

– frame structures;

– bit rates;

–formats for mapping client signals.

光传送序列（OTH）支持各种体系结构（即点对点、环形和网孔形体系结构）光网络的运行和管理。

依据光传送序列（OTH）、多波长光网络支持中的开销功能、帧结构比特率及映射客户信号的方式，本建议定义了光传送网络的接口，以便将这些接口用于光网络的子网内部和子网之间。

2、optical transport module (OTM-n.m): The OTM is the information structure that is transported across an ONNI. The index n and m define the number of supported wavelengths and bit rates at the interface. Two OTM structures are defined:

The OTM with full functionality (OTM-n.m) is the information structure used to support optical transmission section (OTS) layer connections in the OTN. The characteristic information of the optical transmission section layer (OTS_CI) consists of information payload (OTS_CI_PLD) and optical transmission section overhead information fields (OTS_CI_OH). The optical transmission section overhead (OTS_OH) information fields are contained within the OTM overhead signal (OOS) information structure. The OTM-n.m consists of up to n multiplexed optical channels and an OTM overhead signal to support the non-associated overhead.

The OTM with reduced functionality (OTM-nr.m/OTM-0) is the information structure used to support optical physical section (OPS) layer connections in the OTN. The characteristic information of the optical physical section layer (OPS_CI) consists of information payload (OPS_CI_PLD). OTM-0 consists of a single optical channel without a specific colour assigned. The OTM-nr.m consists of up to n multiplexed optical channels. Non-associated overhead is not supported

光传送模块（OTM）：OTM是穿越ONNI传送的信息结构。n和m定义了接口支持的波长数量和比特率。定义了两种OTM：完全功能OTM（OTM-n.m）和简化功能OTM（OTM-0和OTM-nr.m）。

完全功能OTM（OTM-n.m）是用于支持OTN中光传输段（OTS）层连接的信息结构。光传输段层的特征信息（OTS_CI）由信息净荷（OTS_CI_PLD）和光传输段开销信息（OTS_CI_OH）组成。光传输段开销（OTS_OH）信息包含在OTM开销信号（OOS）信息结构中。为了支持非联合开销，完全功能OTM-n.m由最多n个复用的光信道和一个OTM开销构成。

简化功能OTM（OTM-nr.m/OTM-0）是用于支持OTN中光物理段（OPS）层连接的信息结构。光物理段层的特征信息（OPS_CI）由信息净荷（OPS_CI_PLD）组成。OTM-0由不具有分配特定颜色的单个光信道构成。OTM-nr.m最多由n个复用光信道组成。不支持非联合开销。

3、optical channel (OCh[r]): The OCh is the information structure used to support the OCh

trail. Two OCh structures are defined.

The OCh client signals defined in this Recommendation are the OTUk signals. Other digital client

signals (e.g., STM-n, GbE) may be supported by the OTM.

Optical channel with full functionality (OCh): The OCh is an information structure consisting of the information payload (OCh_PLD) with a certain bandwidth and non-associated overhead (OCh_OH) for management of the optical channel.

Optical channel with reduced functionality (OChr): The OChr is an information structure consisting of the information payload (OCh_PLD) with a certain bandwidth. Non-associated overhead is not supported.

光信道（OCh）：OCh是用于支持OCh踪迹的信号结构。定义了两种结构的OCh。

本建议中定义的OCh客户信号为OTUk信号。可以通过OTM支持其他数字客户信号（即STM-n和GbE）。

完全功能光信道（OCh）：为了管理光信道，OCh是一种由具有特定带宽和非联合开销（OCh_OH）的、信息净荷（OCh_PLD）组成的信息结构。

简化功能光信道（OChr）：OChr是一种由具有特定带宽的、信息净荷组成的信息结构。不支持非联合开销。

4、optical channel transport unit (OTUk[V]): The OTUk is the information structure used for transport of an ODUk over one or more optical channel connections. It consists of the optical channel data unit and OTUk related overhead (FEC and overhead for management of an optical channel connection). It is characterized by its frame structure, bit rate, and bandwidth. Two versions of the OTUk are defined:

Completely standardized OTUk (OTUk): The completely standardized OTUk is used on OTM IrDIs and may be used on OTM IaDIs. Functionally standardized OTUk (OTUkV): The partly standardized OTUk is used on OTM IaDIs.

光信道传送单元（OTUk）：OTUk是为了在一个或多个光信道连接上进行光信道数据单元（ODUk）传送的信息结构。它由ODUk和OTUk相关开销（用于光信道连接的FEC和开销）组成。它由其帧结构、比特率及带宽规范。定义了两种版本的OTUk。

完全标准化OTUk（OTUk）：完全标准化OTUk可以用于OTM IrDIs和OTM IaDIs。

功能标准化OTUk（OTUkV）：部分标准化OTUk用于OTM IaDIs。

5、optical channel payload unit (OPUk): The OPUk is the information structure used to adapt client information for transport over an optical channel. It comprises client information together with any overhead needed to perform rate adaptation between the client signal rate and the OPUk payload rate and other OPUk overhead supporting the client signal transport. This overhead is adaptation specific.

光信道净荷单元（OPUk）：OPUk是为了用于在一个光信道中传送适配客户信息的信息结构。它由客户信息与需要在客户信号比特率与OPUk比特率之间完成速率适配的任何开销和支持客户信号传送的其他OPUk开销一起组成。该开销是适配特定的。

6、optical multiplex unit (OMU-n, n ≥ 1): The OMU-n is the information structure used to support optical multiplex section (OMS) layer connections in the OTN. The characteristic information of the optical multiplex section layer (OMS_CI) consists of information payload (OMS_CI_PLD) and optical multiplex section overhead information fields (OMS_CI_OH). The OMS_CI_PLD consists of the OCG-n payload. The OMS_CI_OH consists of the OCG-n overhead and OMS specific overhead and is transported within the OOS information structure. The order of the OMU is defined by the order of the OCG that it supports

光复用单元（OMU-n, n ≥ 1）：OMU-n是用于在OTN中支持光复用段（OMS）层连接的信息结构。光复用段层的特定信息（OMS_CI）由信息净荷（OMS_CI_PLD）和光复用段开销信息（OMS_CI_OH）组成。OMS_CI_PLD由OCG-n净荷组成。OMS_CI_OH由OCG-n开销和OMS特定开销组成，并且在一个OOS信息结构中传送。OMU的阶数支持的OCG阶数决定。

7、optical transport network node interface (ONNI): The interface at an optical transport network node which is used to interconnect with another optical transport network node.

光传送网络节点接口（ONNI）：用于与其他光传送网络节点连接的、在光传送网络节点处的接口。

8、OTM overhead signal (OOS): The OOS is the information structure used for transport of OTM non-associated overhead over the optical supervisory channel. The non-associated overhead consists of the optical transmission section overhead, optical multiplex section overhead and optical channel non-associated overhead. It is characterized by its frame structure, bit rate and bandwidth.

OTM开销信号（OOS）：OOS是用于在光监控信道上进行OTM非联合开销传送的信息结构。非联合开销由光传输段开销、光复用段开销和光信道非联合开销组成。它由其帧结构、比特率及带宽规范。

9、optical supervisory channel (OSC): The physical carrier outside of the amplifier band that provides transport of the OTM overhead signal.

光信道监控信道（OSC）：提供OTM开销信号传送的放大器带外物理载波。

10、OTUk, ODUk and OPUk overhead assignment: The assignment of overhead in the optical

channel transport/data/payload unit signal to each part is defined in Figure 5-1.

OTUk、ODUk和OPUk开销分配：光信道传送/数据/净荷单元信号到每一部分中的开销分配如下。

图5.1

11、Optical transport network interface structure

The optical transport network as specified in ITU-T Rec. G.872 defines two interface classes:

-  Inter-domain interface (IrDI);

-  Intra-domain interface (IaDI).

The basic signal structure is shown in Figure 6-1.

光传送网络接口结构

ITU-T G.872建议中规范的光传送网络定义了两种接口类型：域间接口（IrDI）和域内接口（IaDI）。

图6.1

12、optical transport network（OTN）: a transport network bounded by optical channel access points. An Optical Transport Network (OTN) is composed of a set of Optical Network Elements connected by optical fibre links, able to provide functionality of transport, multiplexing, routing, management, supervision and survivability of optical channels carrying client signals, according to the requirements given in ITU-T G.872.

光传送网络（OTN）：一种由光信道接入点约束的传送网络。根据ITU-T G.872建议给定的要求，OTN由一组通过光纤链路连接的、能够提供携带客户信号的传送、复用、路由发现、管理功能、监控和生存性功能的光网元组成。

13、access point（AP）: A "reference point" that consists of the pair of co-located "unidirectional

access" points, and therefore represents the binding between the trail termination and adaptation functions

接入点（AP）：由一对共点“单向接入”点组成的“参考点”。所以，接入点代表踪迹终结和适配功能之间的绑定关系。