Internet Engineering Task Force (IETF) H. Li
Request for Comments: 6456 R. Zheng
Category: Informational Huawei Technologies
ISSN: 2070-1721 A. Farrel
Old Dog Consulting
November 2011
Internet Engineering Task Force (IETF) H. Li
Request for Comments: 6456 R. Zheng
Category: Informational Huawei Technologies
ISSN: 2070-1721 A. Farrel
Old Dog Consulting
November 2011
Multi-Segment Pseudowires in Passive Optical Networks
无源光网络中的多段伪线
Abstract
摘要
This document describes the application of MPLS multi-segment pseudowires (MS-PWs) in a dual-technology environment comprising a Passive Optical Network (PON) and an MPLS Packet Switched Network (PSN).
本文档描述了MPLS多段伪线（MS PWs）在包括无源光网络（PON）和MPLS分组交换网络（PSN）的双技术环境中的应用。
PON technology may be used in mobile backhaul networks to support the end segments closest to the aggregation devices. In these cases, there may be a very large number of pseudowire (PW) Terminating Provider Edge (T-PE) nodes. The MPLS control plane could be used to provision these end segments, but support for the necessary protocols would complicate the management of the T-PEs and would significantly increase their expense. Alternatively, static, or management plane, configuration could be used to configure the end segments, but the very large number of such segments in a PON places a very heavy burden on the network manager.
PON技术可用于移动回程网络中，以支持最接近聚合设备的终端段。在这些情况下，可能会有大量的伪线（PW）端接提供程序边缘（T-PE）节点。MPLS控制平面可用于提供这些端段，但对必要协议的支持将使T-PE的管理复杂化，并将显著增加其费用。或者，可以使用静态或管理平面配置来配置终端段，但是PON中此类段的数量非常大，这给网络管理器带来了非常沉重的负担。
This document describes how to set up the end segment of an end-to-end MPLS PW over a Gigabit-capable Passive Optical Network (G-PON) or 10 Gigabit-capable Passive Optical Network (XG-PON) using the G-PON and XG-PON management protocol, Optical Network Termination Management and Control Interface (OMCI). This simplifies and speeds up PW provisioning compared with manual configuration.
本文档描述了如何使用G-PON和XG-PON管理协议、光网络终端管理和控制接口（OMCI）在千兆无源光网络（G-PON）或万兆无源光网络（XG-PON）上设置端到端MPLS PW的端段。与手动配置相比，这简化并加快了PW配置。
This document also shows how an MS-PW may be constructed from an end segment supported over a PON, and switched to one or more segments supported over an MPLS PSN.
本文档还展示了如何从PON支持的端段构造MS-PW，并切换到MPLS PSN支持的一个或多个段。
Status of This Memo
关于下段备忘
This document is not an Internet Standards Track specification; it is published for informational purposes.
本文件不是互联网标准跟踪规范；它是为了提供信息而发布的。
This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Not all documents approved by the IESG are a candidate for any level of Internet Standard; see Section 2 of RFC 5741.
本文件是互联网工程任务组（IETF）的产品。它代表了IETF社区的共识。它已经接受了公众审查，并已被互联网工程指导小组（IESG）批准出版。并非IESG批准的所有文件都适用于任何级别的互联网标准；见RFC 5741第2节。
Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc6456.
有关本文件当前状态、任何勘误表以及如何提供反馈的信息，请访问http://www.rfc-editor.org/info/rfc6456.
Copyright Notice
版权公告
Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved.
版权所有（c）2011 IETF信托基金和确定为文件作者的人员。版权所有。
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.
本文件受BCP 78和IETF信托有关IETF文件的法律规定的约束(http://trustee.ietf.org/license-info)自本文件出版之日起生效。请仔细阅读这些文件，因为它们描述了您对本文件的权利和限制。从本文件中提取的代码组件必须包括信托法律条款第4.e节中所述的简化BSD许可证文本，并提供简化BSD许可证中所述的无担保。
Table of Contents
目录
1. Introduction ....................................................2
2. Terminology for G-PON/XG-PON ....................................5
3. Multi-Segment Pseudowire over PON Network Reference Model .......6
4. Label Provisioning for Pseudowires over PON .....................9
5. Security Considerations .........................................9
6. References .....................................................10
6.1. Normative References ......................................10
6.2. Informative References ....................................11
1. Introduction ....................................................2
2. Terminology for G-PON/XG-PON ....................................5
3. Multi-Segment Pseudowire over PON Network Reference Model .......6
4. Label Provisioning for Pseudowires over PON .....................9
5. Security Considerations .........................................9
6. References .....................................................10
6.1. Normative References ......................................10
6.2. Informative References ....................................11
The use of PWs in Packet Switched Networks (PSNs) is defined in [RFC3985]. This architecture is extended in [RFC5659] for multi-segment pseudowires (MS-PWs) satisfying the requirements in [RFC5254]. More detail on MS-PWs is provided in [RFC6073].
[RFC3985]中定义了分组交换网络（PSN）中PWs的使用。该体系结构在[RFC5659]中进行了扩展，用于满足[RFC5254]中要求的多段伪线（MS PWs）。[RFC6073]中提供了有关MS PWs的更多详细信息。
An MS-PW is a useful technology for certain applications where there is an aggregation of paths toward a common point in the network, e.g., mobile backhaul; the segments can be aggregated within tunnels between PW switching points thus improving scalability and reducing the number of control plane adjacencies where a control plane is used.
MS-PW是特定应用的有用技术，其中存在通向网络中公共点的路径聚合，例如，移动回程；这些段可以在PW开关点之间的隧道内聚合，从而提高可伸缩性并减少使用控制平面的控制平面邻接的数量。
Segments of an MS-PW in a PSN can be set up using manual provisioning (static PWs) or using a dynamic control plane such as the Label Distribution Protocol (LDP) [RFC5036] [RFC4447].
PSN中MS-PW的段可以使用手动配置（静态PWs）或使用动态控制平面（如标签分发协议（LDP）[RFC5036][RFC4447]进行设置。
In many scenarios, in access and metro networks, a Passive Optical Network (PON) provides longer distance, higher bandwidth, and better economy than other technologies such as point-to-point Ethernet or Digital Subscriber Line (DSL). Mobile backhaul with PON is already being deployed.
在许多情况下，在接入网和城域网中，无源光网络（PON）比点对点以太网或数字用户线（DSL）等其他技术提供更长的距离、更高的带宽和更好的经济性。已部署带有PON的移动回程。
Figure A depicts the physical infrastructure of an Optical Distribution Network (ODN).
图A描述了光分配网络（ODN）的物理基础设施。
| |
|<--Optical Distribution Network-->|
| |
| branch main |
+-----+ fibers fiber
Base ------| | | |
Stations ------| ONU |\ | |
------| | \ V |
+-----+ \ |
\ +----------+ |
+-----+ \| | | +-----+
Base ------| | | Optical | V | |
Stations ------| ONU |---------| Splitter |-------------| OLT |
------| | /| | | |
+-----+ / +----------+ +-----+
/
+-----+ /
Base ------| |/
Stations ------| ONU |
------| |
+-----+
| |
|<--Optical Distribution Network-->|
| |
| branch main |
+-----+ fibers fiber
Base ------| | | |
Stations ------| ONU |\ | |
------| | \ V |
+-----+ \ |
\ +----------+ |
+-----+ \| | | +-----+
Base ------| | | Optical | V | |
Stations ------| ONU |---------| Splitter |-------------| OLT |
------| | /| | | |
+-----+ / +----------+ +-----+
/
+-----+ /
Base ------| |/
Stations ------| ONU |
------| |
+-----+
Figure A: Typical PON System Architecture
图A：典型的PON系统架构
In a PON, the Optical Network Unit (ONU) and Optical Line Termination (OLT) are adjacent nodes connected by an Optical Distribution Network (ODN), which consists of optical fibers and optical splitters in a tree topology. The link between each ONU and OLT is simulated as a
在PON中，光网络单元（ONU）和光线路终端（OLT）是由光分配网络（ODN）连接的相邻节点，ODN由树状拓扑中的光纤和光分路器组成。每个ONU和OLT之间的链路模拟为
point-to-point link, and there is no path redundancy between them. The OLT resides in the central office, while ONUs reside in customer premises. ONUs are deployed in huge numbers and so they are cost sensitive. More information about ODNs can be found in [G.984.1].
点对点链路，它们之间没有路径冗余。OLT位于中央办公室，而ONU位于客户场所。ONU部署数量巨大，因此成本敏感。有关ODN的更多信息，请参见[G.984.1]。
In a mobile backhaul network, many 2G and 3G base stations still use legacy interfaces such as Time-Division Multiplexing (TDM) and ATM. Therefore, these native services must be carried across the PON before they can be carried over the PSN using PWs. This document describes how MS-PWs can be constructed with end segments that operate over the PON and are switched to further segments operated over the PSN. In this case, the base stations are connected by access circuits (ACs) to the ONUs, which act as Terminating Provider Edge (T-PE) nodes. The OLT is a Switching Provider Edge (S-PE). This model is shown in Figure B.
在移动回程网络中，许多2G和3G基站仍然使用传统接口，如时分复用（TDM）和ATM。因此，这些本机服务必须先通过PON承载，然后才能使用PWs通过PSN承载。本文件描述了如何使用在PON上运行的端段构建MS PWs，并将其切换到在PSN上运行的其他段。在这种情况下，基站通过接入电路（ACs）连接到onu，onu充当终端提供商边缘（T-PE）节点。OLT是交换提供商边缘（S-PE）。该模型如图B所示。
Routing protocols and dynamic label distribution protocols such as LDP would significantly increase the ONUs' cost and complexity as they place requirements on both hardware and software. Besides the coding and maintenance of these new protocols, a much more powerful CPU and more memory are also necessary for them to run smoothly.
路由协议和动态标签分发协议（如LDP）将显著增加ONU的成本和复杂性，因为它们对硬件和软件都有要求。除了对这些新协议进行编码和维护外，它们还需要更强大的CPU和更多的内存才能顺利运行。
As there is no redundant path between each ONU and the OLT, routing and path selection are not necessary in the PON. Therefore, static provisioning of PW labels between ONUs and the OLT is simple and preferred because it can greatly reduce the cost of an ONU that acts as a T-PE. However, use of a Network Management System (NMS) to provision PWs in a PON would require the network manager to configure each ONU and to configure the OLT once for each PW. Since there may be very many ONUs (and hence very many PWs) in a PON, this requires a large amount of operational effort. Additionally, there is an issue that the configuration of each PW at the OLT and ONU might be inconsistent since these nodes are configured separately.
由于每个ONU和OLT之间没有冗余路径，因此PON中不需要路由和路径选择。因此，ONU和OLT之间的PW标签的静态供应是简单且优选的，因为它可以极大地降低充当T-PE的ONU的成本。然而，使用网络管理系统（NMS）在PON中提供PW需要网络管理器配置每个ONU，并为每个PW配置一次OLT。由于PON中可能有很多ONU（因此也有很多PW），这需要大量的操作工作。此外，存在一个问题，即OLT和ONU处的每个PW的配置可能不一致，因为这些节点是单独配置的。
[G.988] defines the G-PON/XG-PON management protocol called the "ONT Management and Control Interface (OMCI)". OMCI is an implementation requirement for all G-PON/XG-PON systems. If OMCI is used to configure PWs on an ONU, no upgrade to an ONU's hardware is required and the extension to the OMCI implementation is negligible. This provides a way of reducing the cost and complexity of provisioning PWs in a G-PON/XG-PON.
[G.988]定义了称为“ONT管理和控制接口（OMCI）”的G-PON/XG-PON管理协议。OMCI是所有G-PON/XG-PON系统的实施要求。如果OMCI用于在ONU上配置PWs，则不需要升级ONU的硬件，OMCI实现的扩展可以忽略不计。这提供了一种降低G-PON/XG-PON中配置PWs的成本和复杂性的方法。
This document shows how the two technologies (PON and PSN) can be combined to provide an end-to-end multi-segment MPLS PW. The MPLS PWs are also carried over the PON in MPLS Label Switched Path (LSP) tunnels. There is an MPLS LSP tunnel in each direction between each ONU and the OLT in a one-to-one relationship with the underlying G-PON/XG-PON channel. The OLT and ONU perform penultimate hop popping
本文档展示了如何将这两种技术（PON和PSN）结合起来，以提供端到端多段MPLS PW。MPLS PW也通过MPLS标签交换路径（LSP）隧道中的PON传输。在每个ONU和OLT之间的每个方向上都有一个MPLS LSP隧道，与底层G-PON/XG-PON信道呈一对一的关系。OLT和ONU执行倒数第二跳弹出
(PHP) [RFC3031] on this single-hop LSP so no labels are used on the wire for the MPLS LSP tunnel. There is no change to the operation of MPLS PWs, and MPLS packets are carried by the G-PON link layer according to ITU-T [G.984.3amd1] or XG-PON link layer according to ITU-T [G.987.3].
（PHP）[RFC3031]在这个单跳LSP上，因此在MPLS LSP隧道的线路上没有使用标签。MPLS PWs的操作没有变化，MPLS数据包根据ITU-T[G.984.3amd1]由G-PON链路层承载，根据ITU-T[G.987.3]由XG-PON链路层承载。
We defined the following terms derived from [G.987]:
我们定义了源自[G.987]的以下术语：
o Gigabit-capable Passive Optical Network (G-PON). A variant of the Passive Optical Network (PON) access technology supporting transmission rates in excess of 1 Gbit/s and based on the ITU-T G.984.x series of Recommendations [G.984.1], [G.984.4amd2] and [G.984.3amd1].
o 千兆位无源光网络（G-PON）。基于ITU-T G.984.x系列建议[G.984.1]、[G.984.4amd2]和[G.984.3amd1]，支持传输速率超过1 Gbit/s的无源光网络（PON）接入技术的一种变体。
o G-PON Encapsulation Method (GEM). A data frame transport scheme used in G-PON systems that is connection oriented and that supports fragmentation of the user data frames into variable sized transmission fragments.
o G-PON封装方法（GEM）。在G-PON系统中使用的一种数据帧传输方案，面向连接，支持将用户数据帧分割成可变大小的传输片段。
o GEM port. An abstraction of the G-PON adaptation layer representing a logical connection associated with a specific client packet flow between the OLT and the ONU.
o 宝石港。G-PON适配层的抽象，表示与OLT和ONU之间的特定客户端分组流相关联的逻辑连接。
o 10-gigabit-capable Passive Optical Network (XG-PON): A PON system supporting nominal transmission rates on the order of 10 Gbit/s in at least one direction, and implementing the suite of protocols specified in the ITU-T G.987.x series Recommendations.
o 万兆无源光网络（XG-PON）：至少在一个方向上支持10 Gbit/s量级的标称传输速率，并实现ITU-T G.987.x系列建议中规定的一套协议的PON系统。
o XG-PON encapsulation method (XGEM): A data frame transport scheme used in XG PON systems that is connection oriented and that supports fragmentation of user data frames into variable-sized transmission fragments.
o XG-PON封装方法（XGEM）：XG-PON系统中使用的一种数据帧传输方案，面向连接，支持将用户数据帧分割为可变大小的传输片段。
o XGEM port: An abstraction in the XG-PON transmission convergence (XGTC) service adaptation sublayer representing a logical connection associated with a specific client packet flow.
o XGEM端口：XG-PON传输汇聚（XGTC）服务适配子层中的抽象，表示与特定客户端数据包流关联的逻辑连接。
o Optical Distribution Network (ODN). In the PON context, a tree of optical fibers in the access network, supplemented with power or wavelength splitters, filters, or other passive optical devices.
o 光分配网络（ODN）。在无源光网络（PON）环境中，接入网络中的一种光纤树，辅以功率或波长分离器、滤波器或其他无源光学设备。
o Optical Line Termination (OLT). A device that terminates the common (root) endpoint of an ODN; implements a PON protocol, such as that defined by ITU-T G.984 series; and adapts PON PDUs for uplink communications over the provider service interface. The OLT provides management and maintenance functions for the
o 光纤线路终端（OLT）。终止ODN的公共（根）端点的设备；实现PON协议，如ITU-T G.984系列定义的协议；并将PON pdu适配为通过提供商服务接口进行上行链路通信。OLT为系统提供管理和维护功能
subtended ODN and ONUs. In this document, the OLT is a network element with multiple PON ports and uplinks that provide switching capability to the PSN.
分为ODN和ONU。在本文档中，OLT是具有多个PON端口和上行链路的网元，这些端口和上行链路为PSN提供交换能力。
o Optical Network Termination (ONT). A single subscriber device that terminates any one of the distributed (leaf) endpoints of an ODN, implements a PON protocol, and adapts PON PDUs to subscriber service interfaces. An ONT is a special case of an ONU.
o 光网络终端（ONT）。终止ODN的任何一个分布式（叶）端点、实现PON协议并使PON PDU适应订户服务接口的单个订户设备。ONT是ONU的特例。
o Optical Network Unit (ONU). A generic term denoting a device that terminates any one of the distributed (leaf) endpoints of an ODN, implements a PON protocol, and adapts PON PDUs to subscriber service interfaces. In some contexts, an ONU implies a multiple subscriber device. In this document, an ONU is a Provider Edge (PE) node with one or more ACs that map to the service interfaces. The ONU acts as a T-PE.
o 光网络单元（ONU）。一个通用术语，表示终止ODN的任何一个分布式（叶）端点、实现PON协议并使PON PDU适应订户服务接口的设备。在某些上下文中，ONU意味着多用户设备。在本文档中，ONU是具有一个或多个映射到服务接口的ACs的提供者边缘（PE）节点。ONU充当T-PE。
o ONT Management and Control Interface (OMCI). The management and control channel between OLT and ONT in PON. The OMCI protocol runs between the OLT Controller and the ONT Controller across a GEM connection that is established at ONT initialization. The OMCI protocol is asymmetric: the Controller in the OLT is the master and the one in the ONT is the slave. A single OLT Controller using multiple instances of the protocol over separate control channels may control multiple ONTs. The OMCI protocol is used to manage the ONT in areas of configuration, fault management, performance, and security.
o ONT管理和控制接口（OMCI）。PON中OLT和ONT之间的管理和控制通道。OMCI协议通过ONT初始化时建立的GEM连接在OLT控制器和ONT控制器之间运行。OMCI协议是不对称的：OLT中的控制器是主控制器，ONT中的控制器是从控制器。通过单独的控制信道使用协议的多个实例的单个OLT控制器可以控制多个ont。OMCI协议用于在配置、故障管理、性能和安全性方面管理ONT。
o Passive Optical Network (PON). An OLT connected, using an ODN, to one or more ONUs or ONTs.
o 无源光网络（PON）。使用ODN连接到一个或多个ONU或ONT的OLT。
[RFC5659] provides several pseudowire emulation edge-to-edge (PWE3) reference architectures for the multi-segment case. These are general models extended from [RFC3985] to enable point-to-point pseudowires through multiple PSN tunnels.
[RFC5659]为多段情况提供了几种伪线仿真边到边（PWE3）参考体系结构。这些是从[RFC3985]扩展而来的通用模型，可通过多个PSN隧道实现点对点伪线。
A G-PON/XG-PON consists of an OLT, an ODN, and multiple ONUs. The ODN is actually a fiber tree that provides physical connections between the OLT and the ONUs. G-PON/XG-PON has its own physical layer and link layer. A GEM/XGEM port is a logical point-to-point connection between the OLT and each ONU over GPON Transmission Convergence (GTC) layer/XG-PON transmission convergence (XGTC) layer. There can be more than one GEM/XGEM port between the OLT and an individual ONU. Each GEM/XGEM port can be assigned different Quality of Service (QoS) and bandwidth.
G-PON/XG-PON由一个OLT、一个ODN和多个ONU组成。ODN实际上是一个光纤树，提供OLT和ONU之间的物理连接。G-PON/XG-PON有自己的物理层和链路层。GEM/XGEM端口是OLT和每个ONU之间通过GPON传输汇聚（GTC）层/XG-PON传输汇聚（XGTC）层的逻辑点对点连接。OLT和单个ONU之间可以有多个GEM/XGEM端口。可以为每个GEM/XGEM端口分配不同的服务质量（QoS）和带宽。
Figure B shows how the MS-PW architecture is applied to a network comprising a PON and a PSN. The Terminating PE1 (TPE1) is an ONU and the Switching PE1 (SPE1) is an OLT. One or more PWs run between the ONU and the remote end system (TPE2) to provide service emulation between Customer Edges (CEs) (CE1 and CE2).
图B显示了MS-PW体系结构如何应用于包括PON和PSN的网络。终端PE1（TPE1）是ONU，交换PE1（SPE1）是OLT。一个或多个PW在ONU和远程终端系统（TPE2）之间运行，以在客户边缘（CE）（CE1和CE2）之间提供服务仿真。
In each of the PON and PSN, the PW segments are carried in PSN tunnels. In the PSN, the tunnel is established and operated as normal for PWs (see [RFC3985]). In the PON, the tunnel used is a single-hop MPLS LSP tunnel so that the OLT and ONU are label edge routers. The OLT and ONU make use of PHP on the MPLS LSP tunnel. Since this is a single-hop LSP (there are no MPLS-capable nodes between the OLT and ONU), this means that there is no MPLS encapsulation for the MPLS LSP tunnel on the wire (that is, no label or shim header is used). This results in the on-wire encapsulations shown in Figure C.
在每个PON和PSN中，PW段在PSN隧道中进行。在PSN中，隧道按照PWs的正常方式建立和运行（参见[RFC3985]）。在PON中，使用的隧道是单跳MPLS LSP隧道，因此OLT和ONU是标签边缘路由器。OLT和ONU在MPLS LSP隧道上使用PHP。由于这是一个单跳LSP（OLT和ONU之间没有支持MPLS的节点），这意味着导线上的MPLS LSP隧道没有MPLS封装（也就是说，没有使用标签或垫片头）。这导致了图C所示的在线封装。
Native |<------Multi-Segment Pseudowire------>| Native
Service | GEM/XGEM | Service
(AC) | |<--Port-->| | (AC)
| | | | | |
| | | PSN | PSN | |
| | |<-Tunnel->| |<-Tunnel->| | |
| V V V V V V |
| +----+ +-----+ +----+ |
+----+ | |TPE1|===========|S-PE1|==========|TPE2| | +----+
| |------|..... PW.Seg't1....X....PW.Seg't3.....|-------| |
| CE1| | | | | | | | | |CE2 |
| |------|..... PW.Seg't2....X....PW.Seg't4.....|-------| |
+----+ | | |===========| |==========| | | +----+
Base ^ +----+ +-----+ +----+ ^
Station | Provider Edge 1 ^ Provider Edge 2 |
| ONU | |
| PW switching point |
| OLT |
| |
|<------------------ Emulated Service --------------->|
Native |<------Multi-Segment Pseudowire------>| Native
Service | GEM/XGEM | Service
(AC) | |<--Port-->| | (AC)
| | | | | |
| | | PSN | PSN | |
| | |<-Tunnel->| |<-Tunnel->| | |
| V V V V V V |
| +----+ +-----+ +----+ |
+----+ | |TPE1|===========|S-PE1|==========|TPE2| | +----+
| |------|..... PW.Seg't1....X....PW.Seg't3.....|-------| |
| CE1| | | | | | | | | |CE2 |
| |------|..... PW.Seg't2....X....PW.Seg't4.....|-------| |
+----+ | | |===========| |==========| | | +----+
Base ^ +----+ +-----+ +----+ ^
Station | Provider Edge 1 ^ Provider Edge 2 |
| ONU | |
| PW switching point |
| OLT |
| |
|<------------------ Emulated Service --------------->|
Figure B: MS-PW over PON Network Reference Model
图B:PON上的MS-PW网络参考模型
Base ----AC-- TPE1--PW over PON--SPE1--PW over PSN--TPE2--AC------
Station
---------- ----------
-------- |Packetized| |Packetized| --------
|Native | |Native | |Native | |Native |
|Service | |Service | |Service | |Service |
-------- |----------| |----------| --------
|Control | |Control |
|Word | |Word |
|----------| |----------|
|PW Label | |PW Label |
|----------| |----------|
|GEM/XGEM | |MPLS |
|----------| |Tunnel |
|GPON/XGPON| |Label |
|-Phy | | |
---------- |----------|
|Link Layer|
|----------|
|Phy |
----------
Figure C: On-Wire Data Encapsulations for MS-PWs
Base ----AC-- TPE1--PW over PON--SPE1--PW over PSN--TPE2--AC------
Station
---------- ----------
-------- |Packetized| |Packetized| --------
|Native | |Native | |Native | |Native |
|Service | |Service | |Service | |Service |
-------- |----------| |----------| --------
|Control | |Control |
|Word | |Word |
|----------| |----------|
|PW Label | |PW Label |
|----------| |----------|
|GEM/XGEM | |MPLS |
|----------| |Tunnel |
|GPON/XGPON| |Label |
|-Phy | | |
---------- |----------|
|Link Layer|
|----------|
|Phy |
----------
Figure C: On-Wire Data Encapsulations for MS-PWs
It should be noted that all PW segments are of the same technology, which is packet encapsulated.
应该注意的是，所有PW段都采用相同的技术，采用分组封装。
The use of the PW label enables multiple PWs to be multiplexed over a single GEM/XGEM port within the MPLS LSP tunnel. This enables the traffic for multiple base stations to be kept separate and allows different services and separate ACs for a single base station to be supported. Furthermore, the multiple ACs at an ONU can belong to different native services.
使用PW标签可以在MPLS LSP隧道内的单个GEM/XGEM端口上多路复用多个PW。这使得多个基站的通信量保持独立，并允许为单个基站支持不同的服务和独立的ACs。此外，ONU处的多个ac可以属于不同的本机服务。
At the same time, each ONU can support more than one GEM/XGEM port (each supporting a single MPLS LSP tunnel) connecting it to the OLT. This allows greater bandwidth and so more PWs. It may also be used to provide a simple way to aggregate PWs intended to be routed across different PSN tunnels in the core network, or even across different core networks.
同时，每个ONU可以支持多个将其连接到OLT的GEM/XGEM端口（每个端口支持一个MPLS LSP隧道）。这允许更大的带宽和更多的PW。它还可用于提供一种简单的方法来聚合拟跨核心网络中的不同PSN隧道路由的PW，甚至跨不同的核心网络路由。
At present, Ethernet over GEM/XGEM is the dominant encapsulation in G-PON/XG-PON. For fast deployment of MPLS over G-PON/XG-PON, putting MPLS PWs over Ethernet over GEM/XGEM is an alternative way of transporting MPLS PWs over G-PON/XG-PON with existing hardware.
目前，GEM/XGEM上的以太网是G-PON/XG-PON中的主要封装。为了在G-PON/XG-PON上快速部署MPLS，在GEM/XGEM上通过以太网放置MPLS PWs是使用现有硬件在G-PON/XG-PON上传输MPLS PWs的另一种方法。
For an MS-PW with a segment running over a PON, where the OLT acts as an S-PE and the ONU as a T-PE, PW provisioning can be performed through static configuration, e.g., from an NMS. However, in this model, each ONU has to be configured as each PW is set up. The huge number of ONUs (and PWs) makes this method quite forbidding.
对于在PON上运行段的MS-PW，其中OLT充当S-PE，ONU充当T-PE，PW供应可以通过静态配置执行，例如从NMS执行。然而，在此模型中，每个ONU都必须在每个PW设置时进行配置。大量的ONU（和PW）使得这种方法非常禁止。
The labor of provisioning static labels at the ONUs for PWs can be significantly reduced by using a management protocol over PON. This approach keeps the ONU simple by not requiring the implementation of a new dynamic control protocol.
通过使用PON上的管理协议，可以显著减少在ONU处为PWs提供静态标签的工作量。这种方法不需要实现新的动态控制协议，从而使ONU保持简单。
The usual management protocol in a G-PON/XG-PON system used to manage and control ONUs is OMCI. It is used to perform all configuration of the G-PON/XG-PON physical layer and data GTC/XGTC layer on ONUs. Per [G.984.4amd2] and [G.988], OMCI can also be used to set up PWs and the MPLS LSP Tunnels from ONUs to OLT. When using OMCI to provision PWs in a G-PON/XG-PON, the network manager sends configuration information to the OLT only. The OLT will select suitable PW labels and send all PW and MPLS LSP tunnel parameters to the ONUs through OMCI. The AC can be identified in the OMCI signaling so that the network manager does not need to configure the PWs at each ONU.
G-PON/XG-PON系统中用于管理和控制ONU的常用管理协议是OMCI。它用于在ONU上执行G-PON/XG-PON物理层和数据GTC/XGTC层的所有配置。根据[G.984.4amd2]和[G.988]，OMCI还可用于设置从ONU到OLT的PWs和MPLS LSP隧道。当使用OMCI在G-PON/XG-PON中提供PWs时，网络管理器仅向OLT发送配置信息。OLT将选择合适的PW标签，并通过OMCI向ONU发送所有PW和MPLS LSP隧道参数。可以在OMCI信令中识别AC，以便网络管理器不需要在每个ONU处配置PWs。
OMCI supports the configuration of a number of PW types including TDM, ATM, and Ethernet. The protocol can also be used to allow the ONU to notify the OLT of the status of the AC.
OMCI支持多种PW类型的配置，包括TDM、ATM和以太网。该协议还可用于允许ONU将AC的状态通知OLT。
This document describes a variation of a multi-segment pseudowire running over an MPLS PSN, in which one (or both) of the MPLS PSNs that provides connectivity between a T-PE and its associated S-PE is replaced by a G-PON/XG-PON PSN. The security considerations that apply to the PW itself [RFC3985] [RFC4385] are unchanged by this change in PSN type. For further considerations of PW security, see the security considerations section of the specific PW type being deployed.
本文档描述了在MPLS PSN上运行的多段伪线的一种变体，其中提供T-PE及其相关S-PE之间连接的一个（或两个）MPLS PSN被G-PON/XG-PON PSN替换。适用于PW本身[RFC3985][RFC4385]的安全注意事项因PSN类型的更改而保持不变。有关PW安全性的更多注意事项，请参阅正在部署的特定PW类型的安全注意事项部分。
G-PON/XG-PON [G.987.3] [G.984.3amd1] includes security mechanisms that are as good as those provided in a well-secured MPLS PSN. The use of a G-PON/XG-PON PSN in place of an MPLS PSN therefore does not increase the security risk of a multi-segment pseudowire.
G-PON/XG-PON[G.987.3][G.984.3amd1]包括与安全性良好的MPLS PSN中提供的安全机制一样好的安全机制。因此，使用G-PON/XG-PON PSN代替MPLS PSN不会增加多段伪线的安全风险。
Protecting against an attack at the physical or data link layer of the PON is out of the scope of this document.
在PON的物理层或数据链路层防止攻击不在本文档范围内。
The MPLS control plane and management plane mechanisms are unchanged by this document. This document introduces OMCI as a provisioning mechanism that runs between the OLT Controller and the ONT Controller across a GEM connection that is established at ONT initialization. In other words, the protocol runs on an in-fiber control channel. That means that injection and modification of OMCI messages would be very hard (harder, for example, than injection or modification in an MPLS Associated Channel Header (ACH) that has been accepted to provide adequate security by isolation ([RFC4385] and [RFC5586]).
MPLS控制平面和管理平面机制在本文档中保持不变。本文档介绍OMCI作为一种配置机制，通过在ONT初始化时建立的GEM连接在OLT控制器和ONT控制器之间运行。换句话说，该协议在光纤内控制信道上运行。这意味着OMCI消息的注入和修改将非常困难（例如，比通过隔离（[RFC4385]和[RFC5586]）提供足够安全性的MPLS相关通道报头（ACH）中的注入或修改更困难）。
[G.984.1] ITU-T, "Gigabit-capable passive optical networks (GPON): General characteristics", March 2008, <http://www.itu.int/rec/T-REC-G.984.1-200803-I>.
[G.984.1]ITU-T，“千兆无源光网络（GPON）：一般特征”，2008年3月<http://www.itu.int/rec/T-REC-G.984.1-200803-I>.
[G.984.3amd1] ITU-T, "Gigabit-capable Passive Optical Networks (G-PON): Transmission convergence layer specification", February 2009, <http://www.itu.int/rec/T-REC-G.984.3-200902-I!Amd1>.
[G.984.3amd1]ITU-T，“千兆无源光网络（G-PON）：传输汇聚层规范”，2009年2月<http://www.itu.int/rec/T-REC-G.984.3-200902-I!Amd1>。
[G.987] ITU-T, "10-Gigabit-capable passive optical network (XG-PON) systems: Definitions, abbreviations, and acronyms", October 2010, <http://www.itu.int/rec/T-REC-G.987-201010-I>.
[G.987]ITU-T，“具有万兆能力的无源光网络（XG-PON）系统：定义、缩写和首字母缩略词”，2010年10月<http://www.itu.int/rec/T-REC-G.987-201010-I>.
[G.987.3] ITU-T, "10-Gigabit-capable passive optical networks (XG-PON): Transmission convergence (TC) layer specification", October 2010, <http://www.itu.int/rec/T-REC-G.987.3-201010-I/en>.
[G.987.3]ITU-T，“10千兆无源光网络（XG-PON）：传输汇聚（TC）层规范”，2010年10月<http://www.itu.int/rec/T-REC-G.987.3-201010-I/en>.
[G.988] ITU-T, "ONU management and control interface (OMCI) specification", October 2010, <http://www.itu.int/rec/T-REC-G.988-201010-I>.
[G.988]ITU-T，“ONU管理和控制接口（OMCI）规范”，2010年10月<http://www.itu.int/rec/T-REC-G.988-201010-I>.
[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol Label Switching Architecture", RFC 3031, January 2001.
[RFC3031]Rosen，E.，Viswanathan，A.，和R.Callon，“多协议标签交换体系结构”，RFC 30312001年1月。
[RFC3985] Bryant, S., Ed., and P. Pate, Ed., "Pseudo Wire Emulation Edge-to-Edge (PWE3) Architecture", RFC 3985, March 2005.
[RFC3985]Bryant，S.，Ed.，和P.Pate，Ed.，“伪线仿真边到边（PWE3）架构”，RFC 39852005年3月。
[RFC4385] Bryant, S., Swallow, G., Martini, L., and D. McPherson, "Pseudowire Emulation Edge-to-Edge (PWE3) Control Word for Use over an MPLS PSN", RFC 4385, February 2006.
[RFC4385]Bryant，S.，Swallow，G.，Martini，L.，和D.McPherson，“用于MPLS PSN的伪线仿真边到边（PWE3）控制字”，RFC 43852006年2月。
[RFC4447] Martini, L., Ed., Rosen, E., El-Aawar, N., Smith, T., and G. Heron, "Pseudowire Setup and Maintenance Using the Label Distribution Protocol (LDP)", RFC 4447, April 2006.
[RFC4447]Martini，L.，Ed.，Rosen，E.，El Aawar，N.，Smith，T.，和G.Heron，“使用标签分发协议（LDP）的伪线设置和维护”，RFC 4447，2006年4月。
[RFC5036] Andersson, L., Ed., Minei, I., Ed., and B. Thomas, Ed., "LDP Specification", RFC 5036, October 2007.
[RFC5036]Andersson，L.，Ed.，Minei，I.，Ed.，和B.Thomas，Ed.，“LDP规范”，RFC 5036，2007年10月。
[RFC5254] Bitar, N., Ed., Bocci, M., Ed., and L. Martini, Ed., "Requirements for Multi-Segment Pseudowire Emulation Edge-to-Edge (PWE3)", RFC 5254, October 2008.
[RFC5254]Bitar，N.，Ed.，Bocci，M.，Ed.，和L.Martini，Ed.，“多段伪线仿真边到边（PWE3）的要求”，RFC 5254，2008年10月。
[RFC5586] Bocci, M., Ed., Vigoureux, M., Ed., and S. Bryant, Ed., "MPLS Generic Associated Channel", RFC 5586, June 2009.
[RFC5586]Bocci，M.，Ed.，Vigoureux，M.，Ed.，和S.Bryant，Ed.，“MPLS通用关联信道”，RFC 55862009年6月。
[RFC5659] Bocci, M. and S. Bryant, "An Architecture for Multi-Segment Pseudowire Emulation Edge-to-Edge", RFC 5659, October 2009.
[RFC5659]Bocci，M.和S.Bryant，“多段伪线边到边仿真的体系结构”，RFC 5659，2009年10月。
[G.984.4amd2] ITU-T, "Gigabit-capable passive optical networks (G-PON): ONT management and control interface specification", November 2009, <http://www.itu.int/rec/T-REC-G.984.4-200911-I!Amd2>.
[G.984.4amd2]ITU-T，“千兆无源光网络（G-PON）：ONT管理和控制接口规范”，2009年11月<http://www.itu.int/rec/T-REC-G.984.4-200911-I!Amd2>。
[RFC6073] Martini, L., Metz, C., Nadeau, T., Bocci, M., and M. Aissaoui, "Segmented Pseudowire", RFC 6073, January 2011.
[RFC6073]Martini，L.，Metz，C.，Nadeau，T.，Bocci，M.和M.Aissaoui，“分段伪线”，RFC 60732011年1月。
Authors' Addresses
作者地址
Hongyu Li Huawei Technologies Huawei Industrial Base Shenzhen China
李宏宇华为技术华为工业基地中国深圳
EMail: hongyu.lihongyu@huawei.com
EMail: hongyu.lihongyu@huawei.com
Ruobin Zheng Huawei Technologies Huawei Industrial Base Shenzhen China
若彬郑华为技术华为工业基地中国深圳
EMail: robin@huawei.com
EMail: robin@huawei.com
Adrian Farrel Old Dog Consulting
阿德里安·法雷尔老狗咨询公司
EMail: adrian@olddog.co.uk
EMail: adrian@olddog.co.uk