Network Working Group K. Shiomoto
Request for Comments: 5212 NTT
Category: Informational D. Papadimitriou
Alcatel-Lucent
JL. Le Roux
France Telecom
M. Vigoureux
Alcatel-Lucent
D. Brungard
AT&T
July 2008
Network Working Group K. Shiomoto
Request for Comments: 5212 NTT
Category: Informational D. Papadimitriou
Alcatel-Lucent
JL. Le Roux
France Telecom
M. Vigoureux
Alcatel-Lucent
D. Brungard
AT&T
July 2008
Requirements for GMPLS-Based Multi-Region and Multi-Layer Networks (MRN/MLN)
基于GMPLS的多区域和多层网络（MRN/MLN）的要求
Status of This Memo
关于下段备忘
This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited.
本备忘录为互联网社区提供信息。它没有规定任何类型的互联网标准。本备忘录的分发不受限制。
Abstract
摘要
Most of the initial efforts to utilize Generalized MPLS (GMPLS) have been related to environments hosting devices with a single switching capability. The complexity raised by the control of such data planes is similar to that seen in classical IP/MPLS networks. By extending MPLS to support multiple switching technologies, GMPLS provides a comprehensive framework for the control of a multi-layered network of either a single switching technology or multiple switching technologies.
大多数最初使用通用MPLS（GMPLS）的努力都与承载具有单一交换能力的设备的环境有关。控制此类数据平面所增加的复杂性与经典IP/MPLS网络中的复杂性相似。通过扩展MPLS以支持多种交换技术，GMPLS为控制单一交换技术或多种交换技术的多层网络提供了一个全面的框架。
In GMPLS, a switching technology domain defines a region, and a network of multiple switching types is referred to in this document as a multi-region network (MRN). When referring in general to a layered network, which may consist of either single or multiple regions, this document uses the term multi-layer network (MLN). This document defines a framework for GMPLS based multi-region / multi-layer networks and lists a set of functional requirements.
在GMPLS中，交换技术领域定义了一个区域，并且在本文档中，多种交换类型的网络称为多区域网络（MRN）。当一般指分层网络时，它可能由单个或多个区域组成，本文件使用术语多层网络（MLN）。本文件定义了基于GMPLS的多区域/多层网络的框架，并列出了一组功能需求。
Table of Contents
目录
1. Introduction ....................................................3
1.1. Scope ......................................................4
2. Conventions Used in This Document ...............................5
2.1. List of Acronyms ...........................................6
3. Positioning .....................................................6
3.1. Data Plane Layers and Control Plane Regions ................6
3.2. Service Layer Networks .....................................7
3.3. Vertical and Horizontal Interaction and Integration ........8
3.4. Motivation .................................................9
4. Key Concepts of GMPLS-Based MLNs and MRNs ......................10
4.1. Interface Switching Capability ............................10
4.2. Multiple Interface Switching Capabilities .................11
4.2.1. Networks with Multi-Switching-Type-Capable
Hybrid Nodes .......................................12
4.3. Integrated Traffic Engineering (TE) and Resource Control ..12
4.3.1. Triggered Signaling ................................13
4.3.2. FA-LSPs ............................................13
4.3.3. Virtual Network Topology (VNT) .....................14
5. Requirements ...................................................15
5.1. Handling Single-Switching and
Multi-Switching-Type-Capable Nodes ........................15
5.2. Advertisement of the Available Adjustment Resources .......15
5.3. Scalability ...............................................16
5.4. Stability .................................................17
5.5. Disruption Minimization ...................................17
5.6. LSP Attribute Inheritance .................................17
5.7. Computing Paths with and without Nested Signaling .........18
5.8. LSP Resource Utilization ..................................19
5.8.1. FA-LSP Release and Setup ...........................19
5.8.2. Virtual TE Links ...................................20
5.9. Verification of the LSPs ..................................21
5.10. Management ...............................................22
6. Security Considerations ........................................24
7. Acknowledgements ...............................................24
8. References .....................................................25
8.1. Normative References ......................................25
8.2. Informative References ....................................25
9. Contributors' Addresses ........................................26
1. Introduction ....................................................3
1.1. Scope ......................................................4
2. Conventions Used in This Document ...............................5
2.1. List of Acronyms ...........................................6
3. Positioning .....................................................6
3.1. Data Plane Layers and Control Plane Regions ................6
3.2. Service Layer Networks .....................................7
3.3. Vertical and Horizontal Interaction and Integration ........8
3.4. Motivation .................................................9
4. Key Concepts of GMPLS-Based MLNs and MRNs ......................10
4.1. Interface Switching Capability ............................10
4.2. Multiple Interface Switching Capabilities .................11
4.2.1. Networks with Multi-Switching-Type-Capable
Hybrid Nodes .......................................12
4.3. Integrated Traffic Engineering (TE) and Resource Control ..12
4.3.1. Triggered Signaling ................................13
4.3.2. FA-LSPs ............................................13
4.3.3. Virtual Network Topology (VNT) .....................14
5. Requirements ...................................................15
5.1. Handling Single-Switching and
Multi-Switching-Type-Capable Nodes ........................15
5.2. Advertisement of the Available Adjustment Resources .......15
5.3. Scalability ...............................................16
5.4. Stability .................................................17
5.5. Disruption Minimization ...................................17
5.6. LSP Attribute Inheritance .................................17
5.7. Computing Paths with and without Nested Signaling .........18
5.8. LSP Resource Utilization ..................................19
5.8.1. FA-LSP Release and Setup ...........................19
5.8.2. Virtual TE Links ...................................20
5.9. Verification of the LSPs ..................................21
5.10. Management ...............................................22
6. Security Considerations ........................................24
7. Acknowledgements ...............................................24
8. References .....................................................25
8.1. Normative References ......................................25
8.2. Informative References ....................................25
9. Contributors' Addresses ........................................26
Generalized MPLS (GMPLS) extends MPLS to handle multiple switching technologies: packet switching, Layer-2 switching, TDM (Time-Division Multiplexing) switching, wavelength switching, and fiber switching (see [RFC3945]). The Interface Switching Capability (ISC) concept is introduced for these switching technologies and is designated as follows: PSC (packet switch capable), L2SC (Layer-2 switch capable), TDM capable, LSC (lambda switch capable), and FSC (fiber switch capable).
广义MPLS（GMPLS）扩展了MPLS以处理多种交换技术：分组交换、第二层交换、TDM（时分复用）交换、波长交换和光纤交换（参见[RFC3945]）。为这些交换技术引入了接口交换能力（ISC）概念，并将其指定为：PSC（支持分组交换）、L2SC（支持第二层交换机）、TDM、LSC（支持lambda交换机）和FSC（支持光纤交换机）。
The representation, in a GMPLS control plane, of a switching technology domain is referred to as a region [RFC4206]. A switching type describes the ability of a node to forward data of a particular data plane technology, and uniquely identifies a network region. A layer describes a data plane switching granularity level (e.g., VC4, VC-12). A data plane layer is associated with a region in the control plane (e.g., VC4 is associated with TDM, MPLS is associated with PSC). However, more than one data plane layer can be associated with the same region (e.g., both VC4 and VC12 are associated with TDM). Thus, a control plane region, identified by its switching type value (e.g., TDM), can be sub-divided into smaller-granularity component networks based on "data plane switching layers". The Interface Switching Capability Descriptor (ISCD) [RFC4202], identifying the interface switching capability (ISC), the encoding type, and the switching bandwidth granularity, enables the characterization of the associated layers.
在GMPLS控制平面中，交换技术域的表示被称为区域[RFC4206]。交换类型描述节点转发特定数据平面技术数据的能力，并唯一标识网络区域。层描述数据平面交换粒度级别（例如，VC4、VC-12）。数据平面层与控制平面中的区域相关联（例如，VC4与TDM相关联，MPLS与PSC相关联）。然而，可以将多个数据平面层与同一区域相关联（例如，VC4和VC12都与TDM相关联）。因此，通过其交换类型值（例如，TDM）识别的控制平面区域可以基于“数据平面交换层”被细分为更小粒度的组件网络。接口交换能力描述符（ISCD）[RFC4202]识别接口交换能力（ISC）、编码类型和交换带宽粒度，从而能够对相关层进行表征。
In this document, we define a multi-layer network (MLN) to be a Traffic Engineering (TE) domain comprising multiple data plane switching layers either of the same ISC (e.g., TDM) or different ISC (e.g., TDM and PSC) and controlled by a single GMPLS control plane instance. We further define a particular case of MLNs. A multi-region network (MRN) is defined as a TE domain supporting at least two different switching types (e.g., PSC and TDM), either hosted on the same device or on different ones, and under the control of a single GMPLS control plane instance.
在本文档中，我们将多层网络（MLN）定义为一个流量工程（TE）域，包括相同ISC（如TDM）或不同ISC（如TDM和PSC）的多个数据平面交换层，并由单个GMPLS控制平面实例控制。我们进一步定义了MLN的一个特殊情况。多区域网络（MRN）被定义为支持至少两种不同交换类型（例如，PSC和TDM）的TE域，托管在同一设备上或不同设备上，并且在单个GMPLS控制平面实例的控制下。
MLNs can be further categorized according to the distribution of the ISCs among the Label Switching Routers (LSRs):
MLN可以根据ISC在标签交换路由器（LSR）之间的分布进一步分类：
- Each LSR may support just one ISC. Such LSRs are known as single-switching-type-capable LSRs. The MLN may comprise a set of single-switching-type-capable LSRs some of which support different ISCs.
- 每个LSR可能只支持一个ISC。这种LSR被称为单开关型能力LSR。MLN可以包括一组能够切换的lsr，其中一些lsr支持不同的isc。
- Each LSR may support more than one ISC at the same time. Such LSRs are known as multi-switching-type-capable LSRs, and can be further classified as either "simplex" or "hybrid" nodes as defined in Section 4.2.
- 每个LSR可以同时支持多个ISC。此类LSR被称为具有多交换类型能力的LSR，并可进一步分类为第4.2节中定义的“单工”或“混合”节点。
- The MLN may be constructed from any combination of single-switching-type-capable LSRs and multi-switching-type-capable LSRs.
- MLN可以由具有单交换类型能力的lsr和具有多交换类型能力的lsr的任意组合来构造。
Since GMPLS provides a comprehensive framework for the control of different switching capabilities, a single GMPLS instance may be used to control the MLN/MRN. This enables rapid service provisioning and efficient traffic engineering across all switching capabilities. In such networks, TE links are consolidated into a single Traffic Engineering Database (TED). Since this TED contains the information relative to all the different regions and layers existing in the network, a path across multiple regions or layers can be computed using this TED. Thus, optimization of network resources can be achieved across the whole MLN/MRN.
由于GMPLS提供了控制不同交换能力的综合框架，因此可以使用单个GMPLS实例来控制MLN/MRN。这使得跨所有交换功能的快速服务供应和高效流量工程成为可能。在这样的网络中，TE链路被合并到一个单一的流量工程数据库（TED）中。由于此TED包含与网络中存在的所有不同区域和层相关的信息，因此可以使用此TED计算跨多个区域或层的路径。因此，可以在整个MLN/MRN中实现网络资源的优化。
Consider, for example, a MRN consisting of packet-switch-capable routers and TDM cross-connects. Assume that a packet Label Switched Path (LSP) is routed between source and destination packet-switch-capable routers, and that the LSP can be routed across the PSC region (i.e., utilizing only resources of the packet region topology). If the performance objective for the packet LSP is not satisfied, new TE links may be created between the packet-switch-capable routers across the TDM-region (for example, VC-12 links) and the LSP can be routed over those TE links. Furthermore, even if the LSP can be successfully established across the PSC-region, TDM hierarchical LSPs (across the TDM region between the packet-switch capable routers) may be established and used if doing so is necessary to meet the operator's objectives for network resource availability (e.g., link bandwidth). The same considerations hold when VC4 LSPs are provisioned to provide extra flexibility for the VC12 and/or VC11 layers in an MLN.
例如，考虑由分组交换路由器和TDM交叉连接组成的MRN。假设分组标签交换路径（LSP）在源和目标分组交换能力路由器之间路由，并且LSP可以跨PSC区域路由（即，仅利用分组区域拓扑的资源）。如果分组LSP的性能目标不满足，则可以在TDM区域（例如，VC-12链路）上的支持分组交换机的路由器之间创建新的TE链路，并且LSP可以通过那些TE链路路由。此外，即使可以跨PSC区域成功地建立LSP，如果为了满足运营商的网络资源可用性（例如，链路带宽）目标而必须这样做，则可以建立和使用TDM分层LSP（跨支持分组交换机的路由器之间的TDM区域）。当配置VC4 LSP以为MLN中的VC12和/或VC11层提供额外的灵活性时，同样的考虑也适用。
Sections 3 and 4 of this document provide further background information of the concepts and motivation behind multi-region and multi-layer networks. Section 5 presents detailed requirements for protocols used to implement such networks.
本文件第3节和第4节提供了多区域和多层网络背后的概念和动机的进一步背景信息。第5节介绍了用于实现此类网络的协议的详细要求。
Early sections of this document describe the motivations and reasoning that require the development and deployment of MRN/MLN. Later sections of this document set out the required features that the GMPLS control plane must offer to support MRN/MLN. There is no intention to specify solution-specific and/or protocol elements in
本文件的前几节描述了需要开发和部署MRN/MLN的动机和理由。本文件后面的章节列出了GMPLS控制平面必须提供的支持MRN/MLN所需的功能。无意在中指定特定于解决方案和/或协议的元素
this document. The applicability of existing GMPLS protocols and any protocol extensions to the MRN/MLN is addressed in separate documents [MRN-EVAL].
这份文件。现有GMPLS协议和MRN/MLN的任何协议扩展的适用性在单独的文件[MRN-EVAL]中说明。
This document covers the elements of a single GMPLS control plane instance controlling multiple layers within a given TE domain. A control plane instance can serve one, two, or more layers. Other possible approaches such as having multiple control plane instances serving disjoint sets of layers are outside the scope of this document. It is most probable that such a MLN or MRN would be operated by a single service provider, but this document does not exclude the possibility of two layers (or regions) being under different administrative control (for example, by different Service Providers that share a single control plane instance) where the administrative domains are prepared to share a limited amount of information.
本文档涵盖单个GMPLS控制平面实例的元素，该实例控制给定TE域内的多个层。控制平面实例可以服务于一层、两层或更多层。其他可能的方法，例如让多个控制平面实例服务于不相交的层集，不在本文档的范围之内。此类MLN或MRN很可能由单个服务提供商运营，但本文件不排除两个层（或区域）处于不同管理控制下的可能性（例如，由共享单个控制平面实例的不同服务提供商）管理域准备共享有限数量的信息。
For such a TE domain to interoperate with edge nodes/domains supporting non-GMPLS interfaces (such as those defined by other standards development organizations (SDOs)), an interworking function may be needed. Location and specification of this function are outside the scope of this document (because interworking aspects are strictly under the responsibility of the interworking function).
为了使这样的TE域与支持非GMPLS接口（如其他标准开发组织（SDO）定义的接口）的边缘节点/域进行互操作，可能需要一个互操作功能。该功能的位置和规格不在本文件范围内（因为互通方面严格由互通功能负责）。
This document assumes that the interconnection of adjacent MRN/MLN TE domains makes use of [RFC4726] when their edges also support inter-domain GMPLS RSVP-TE extensions.
本文件假设相邻MRN/MLN TE域的互连在其边缘也支持域间GMPLS RSVP-TE扩展时使用[RFC4726]。
Although this is not a protocol specification, the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are used in this document to highlight requirements, and are to be interpreted as described in RFC 2119 [RFC2119].
尽管本规范不是协议规范，但本文件中使用的关键词“必须”、“不得”、“要求”、“应”、“不应”、“应”、“不应”、“建议”、“可”和“可选”用于强调要求，并按照RFC 2119[RFC2119]中的描述进行解释。
In the context of this document, an end-to-end LSP is defined as an LSP that starts in some client layer, ends in the same layer, and may cross one or more lower layers. In terms of switching capabilities, this means that if the outgoing interface on the head-end LSR has interface switching capability X, then the incoming interface on the tail-end LSR also has switching capability X. Further, for any interface traversed by the LSP at any intermediate LSR, the switching capability of that interface, Y, is such that Y >= X.
在本文档的上下文中，端到端LSP定义为从某个客户端层开始，在同一层结束，并可能跨越一个或多个较低层的LSP。就交换能力而言，这意味着如果前端LSR上的传出接口具有接口交换能力X，那么后端LSR上的传入接口也具有交换能力X。此外，对于LSP在任何中间LSR上穿过的任何接口，该接口的交换能力Y，是这样的，Y>=X。
ERO: Explicit Route Object FA: Forwarding Adjacency FA-LSP: Forwarding Adjacency Label Switched Path FSC: Fiber Switching Capable ISC: Interface Switching Capability ISCD: Interface Switching Capability Descriptor L2SC: Layer-2 Switching Capable LSC: Lambda Switching Capable LSP: Label Switched Path LSR: Label Switching Router MLN: Multi-Layer Network MRN: Multi-Region Network PSC: Packet Switching Capable SRLG: Shared Risk Link Group TDM: Time-Division Multiplexing TE: Traffic Engineering TED: Traffic Engineering Database VNT: Virtual Network Topology
ERO:显式路由对象FA:转发邻接FA-LSP:转发邻接标签交换路径FSC:光纤交换能力ISC:接口交换能力ISCD:接口交换能力描述符L2SC:第二层交换能力LSC:Lambda交换能力LSP:标签交换路径LSR:标签交换路由器MLN:多层网络MRN:多区域网络PSC:支持分组交换的SRLG:共享风险链路组TDM:时分复用TE:流量工程TED:流量工程数据库VNT:虚拟网络拓扑
A multi-region network (MRN) is always a multi-layer network (MLN) since the network devices on region boundaries bring together different ISCs. A MLN, however, is not necessarily a MRN since multiple layers could be fully contained within a single region. For example, VC12, VC4, and VC4-4c are different layers of the TDM region.
多区域网络（MRN）通常是多层网络（MLN），因为区域边界上的网络设备将不同的ISC连接在一起。然而，MLN不一定是MRN，因为多层可以完全包含在单个区域内。例如，VC12、VC4和VC4-4c是TDM区域的不同层。
A data plane layer is a collection of network resources capable of terminating and/or switching data traffic of a particular format [RFC4397]. These resources can be used for establishing LSPs for traffic delivery. For example, VC-11 and VC4-64c represent two different layers.
数据平面层是能够终止和/或交换特定格式的数据流量的网络资源集合[RFC4397]。这些资源可用于为流量交付建立LSP。例如，VC-11和VC4-64c代表两个不同的层。
From the control plane viewpoint, an LSP region is defined as a set of one or more data plane layers that share the same type of switching technology, that is, the same switching type. For example, VC-11, VC-4, and VC-4-7v layers are part of the same TDM region. The regions that are currently defined are: PSC, L2SC, TDM, LSC, and FSC. Hence, an LSP region is a technology domain (identified by the ISC type) for which data plane resources (i.e., data links) are represented into the control plane as an aggregate of TE information
从控制平面的观点来看，LSP区域被定义为共享相同类型的交换技术（即，相同的交换类型）的一个或多个数据平面层的集合。例如，VC-11、VC-4和VC-4-7v层是同一TDM区域的一部分。目前定义的区域有：PSC、L2SC、TDM、LSC和FSC。因此，LSP区域是一个技术域（由ISC类型标识），其数据平面资源（即，数据链路）作为TE信息的集合被表示到控制平面中
associated with a set of links (i.e., TE links). For example, VC-11 and VC4-64c capable TE links are part of the same TDM region. Multiple layers can thus exist in a single region network.
与一组链接（即TE链接）关联。例如，支持VC-11和VC4-64c的TE链路是同一TDM区域的一部分。因此，在单个区域网络中可以存在多个层。
Note also that the region may produce a distinction within the control plane. Layers of the same region share the same switching technology and, therefore, use the same set of technology-specific signaling objects and technology-specific value setting of TE link attributes within the control plane, but layers from different regions may use different technology-specific objects and TE attribute values. This means that it may not be possible to simply forward the signaling message between LSRs that host different switching technologies. This is due to changes in some of the signaling objects (for example, the traffic parameters) when crossing a region boundary even if a single control plane instance is used to manage the whole MRN. We may solve this issue by using triggered signaling (see Section 4.3.1).
还请注意，该区域可能会在控制平面内产生差异。相同区域的层共享相同的交换技术，因此，在控制平面内使用相同的技术特定信令对象集和TE链路属性的技术特定值设置，但是来自不同区域的层可以使用不同的技术特定对象和TE属性值。这意味着不可能在承载不同交换技术的lsr之间简单地转发信令消息。这是由于当跨越区域边界时，即使使用单个控制平面实例来管理整个MRN，某些信令对象（例如，业务参数）也会发生变化。我们可以通过使用触发信号解决这个问题（见第4.3.1节）。
A service provider's network may be divided into different service layers. The customer's network is considered from the provider's perspective as the highest service layer. It interfaces to the highest service layer of the service provider's network. Connectivity across the highest service layer of the service provider's network may be provided with support from successively lower service layers. Service layers are realized via a hierarchy of network layers located generally in several regions and commonly arranged according to the switching capabilities of network devices.
服务提供商的网络可以划分为不同的服务层。从提供商的角度来看，客户网络被视为最高的服务层。它连接到服务提供商网络的最高服务层。跨服务提供商网络的最高服务层的连接性可以在连续较低的服务层的支持下提供。服务层通过网络层的层次结构来实现，网络层通常位于多个区域中，并且通常根据网络设备的交换能力来安排。
For instance, some customers purchase Layer-1 (i.e., transport) services from the service provider, some Layer 2 (e.g., ATM), while others purchase Layer-3 (IP/MPLS) services. The service provider realizes the services by a stack of network layers located within one or more network regions. The network layers are commonly arranged according to the switching capabilities of the devices in the networks. Thus, a customer network may be provided on top of the GMPLS-based multi-region/multi-layer network. For example, a Layer-1 service (realized via the network layers of TDM, and/or LSC, and/or FSC regions) may support a Layer-2 network (realized via ATM Virtual Path / Virtual Circuit (VP/VC)), which may itself support a Layer-3 network (IP/MPLS region). The supported data plane relationship is a data plane client-server relationship where the lower layer provides a service for the higher layer using the data links realized in the lower layer.
例如，一些客户从服务提供商处购买第1层（即传输）服务，一些客户从第2层（例如ATM）购买服务，而其他客户则购买第3层（IP/MPLS）服务。服务提供商通过位于一个或多个网络区域内的网络层堆栈来实现服务。通常根据网络中设备的交换能力来布置网络层。因此，可以在基于GMPLS的多区域/多层网络之上提供客户网络。例如，第1层服务（通过TDM和/或LSC和/或FSC区域的网络层实现）可支持第2层网络（通过ATM虚拟路径/虚拟电路（VP/VC）实现），其本身可支持第3层网络（IP/MPLS区域）。支持的数据平面关系是一种数据平面客户机-服务器关系，其中较低层使用较低层中实现的数据链路为较高层提供服务。
Services provided by a GMPLS-based multi-region/multi-layer network are referred to as "multi-region/multi-layer network services". For example, legacy IP and IP/MPLS networks can be supported on top of multi-region/multi-layer networks. It has to be emphasized that delivery of such diverse services is a strong motivator for the deployment of multi-region/multi-layer networks.
基于GMPLS的多区域/多层网络提供的服务称为“多区域/多层网络服务”。例如，可以在多区域/多层网络之上支持传统IP和IP/MPLS网络。必须强调的是，提供如此多样化的服务是部署多区域/多层网络的强大动力。
A customer network may be provided on top of a server GMPLS-based MRN/MLN which is operated by a service provider. For example, a pure IP and/or an IP/MPLS network can be provided on top of GMPLS-based packet-over-optical networks [RFC5146]. The relationship between the networks is a client/server relationship and, such services are referred to as "MRN/MLN services". In this case, the customer network may form part of the MRN/MLN or may be partially separated, for example, to maintain separate routing information but retain common signaling.
可以在服务提供商运营的基于GMPLS的MRN/MLN服务器上提供客户网络。例如，可以在基于GMPLS的光网络分组之上提供纯IP和/或IP/MPLS网络[RFC5146]。网络之间的关系是客户机/服务器关系，此类服务称为“MRN/MLN服务”。在这种情况下，客户网络可以形成MRN/MLN的一部分，或者可以部分分离，例如，以保持单独的路由信息，但保留公共信令。
Vertical interaction is defined as the collaborative mechanisms within a network element that is capable of supporting more than one layer or region and of realizing the client/server relationships between the layers or regions. Protocol exchanges between two network controllers managing different regions or layers are also a vertical interaction. Integration of these interactions as part of the control plane is referred to as vertical integration. Thus, this refers to the collaborative mechanisms within a single control plane instance driving multiple network layers that are part of the same region or not. Such a concept is useful in order to construct a framework that facilitates efficient network resource usage and rapid service provisioning in carrier networks that are based on multiple layers, switching technologies, or ISCs.
垂直交互被定义为网元内的协作机制，能够支持多个层或区域，并实现层或区域之间的客户机/服务器关系。管理不同区域或层的两个网络控制器之间的协议交换也是一种垂直交互。作为控制平面一部分的这些相互作用的集成称为垂直集成。因此，这是指单个控制平面实例内的协作机制，驱动属于或不属于同一区域的多个网络层。这样的概念对于构建一个框架非常有用，该框架有助于在基于多层、交换技术或isc的运营商网络中高效使用网络资源和快速提供服务。
Horizontal interaction is defined as the protocol exchange between network controllers that manage transport nodes within a given layer or region. For instance, the control plane interaction between two TDM network elements switching at OC-48 is an example of horizontal interaction. GMPLS protocol operations handle horizontal interactions within the same routing area. The case where the interaction takes place across a domain boundary, such as between two routing areas within the same network layer, is evaluated as part of the inter-domain work [RFC4726], and is referred to as horizontal integration. Thus, horizontal integration refers to the collaborative mechanisms between network partitions and/or administrative divisions such as routing areas or autonomous systems.
水平交互定义为管理给定层或区域内传输节点的网络控制器之间的协议交换。例如，在OC-48处切换的两个TDM网元之间的控制平面交互是水平交互的示例。GMPLS协议操作处理同一路由区域内的水平交互。交互跨域边界发生的情况，例如在同一网络层内的两个路由区域之间，作为域间工作的一部分进行评估[RFC4726]，称为水平集成。因此，横向集成是指网络分区和/或行政分区（如路由区域或自治系统）之间的协作机制。
This distinction needs further clarification when administrative domains match layer/region boundaries. Horizontal interaction is extended to cover such cases. For example, the collaborative mechanisms in place between two LSC areas relate to horizontal integration. On the other hand, the collaborative mechanisms in place between a PSC (e.g., IP/MPLS) domain and a separate TDM capable (e.g., VC4 Synchronous Digital Hierarchy (SDH)) domain over which it operates are part of the horizontal integration, while it can also be seen as a first step towards vertical integration.
当管理域与层/区域边界匹配时，这种区别需要进一步澄清。水平交互作用被扩展以涵盖此类情况。例如，两个LSC领域之间的协作机制涉及横向整合。另一方面，PSC（例如，IP/MPLS）域和其运行的独立TDM（例如，VC4同步数字体系（SDH））域之间的协作机制是水平集成的一部分，同时也可视为垂直集成的第一步。
The applicability of GMPLS to multiple switching technologies provides a unified control and management approach for both LSP provisioning and recovery. Indeed, one of the main motivations for unifying the capabilities and operations of the GMPLS control plane is the desire to support multi-LSP-region [RFC4206] routing and TE capabilities. For instance, this enables effective network resource utilization of both the Packet/Layer2 LSP regions and the TDM or Lambda LSP regions in high-capacity networks.
GMPLS对多种交换技术的适用性为LSP供应和恢复提供了统一的控制和管理方法。事实上，统一GMPLS控制平面的能力和操作的主要动机之一是希望支持多LSP区域[RFC4206]路由和TE能力。例如，这使得能够在高容量网络中有效地利用分组/层2 LSP区域和TDM或Lambda LSP区域的网络资源。
The rationales for GMPLS-controlled multi-layer/multi-region networks are summarized below:
GMPLS控制的多层/多区域网络的原理总结如下：
- The maintenance of multiple instances of the control plane on devices hosting more than one switching capability not only increases the complexity of the interactions between control plane instances, but also increases the total amount of processing each individual control plane instance must handle.
- 在承载多个交换功能的设备上维护控制平面的多个实例不仅增加了控制平面实例之间交互的复杂性，而且还增加了每个单独控制平面实例必须处理的处理总量。
- The unification of the addressing spaces helps in avoiding multiple identifiers for the same object (a link, for instance, or more generally, any network resource). On the other hand such aggregation does not impact the separation between the control plane and the data plane.
- 寻址空间的统一有助于避免同一对象的多个标识符（例如，链路，或更一般地，任何网络资源）。另一方面，这种聚合不会影响控制平面和数据平面之间的分离。
- By maintaining a single routing protocol instance and a single TE database per LSR, a unified control plane model removes the requirement to maintain a dedicated routing topology per layer and therefore does not mandate a full mesh of routing adjacencies as is the case with overlaid control planes.
- 通过为每个LSR维护一个路由协议实例和一个TE数据库，统一的控制平面模型消除了维护每层专用路由拓扑的要求，因此不像覆盖控制平面那样要求路由邻接的完整网格。
- The collaboration between technology layers where the control channel is associated with the data channel (e.g., packet/framed data planes) and technology layers where the control channel is not directly associated with the data channel (SONET/SDH, G.709, etc.)
- 控制信道与数据信道关联的技术层（例如，分组/帧数据平面）和控制信道与数据信道不直接关联的技术层（SONET/SDH、g.709等）之间的协作
is facilitated by the capability within GMPLS to associate in-band control plane signaling to the IP terminating interfaces of the control plane.
GMPLS内将带内控制平面信令与控制平面的IP端接接口相关联的能力有助于实现这一点。
- Resource management and policies to be applied at the edges of such an MRN/MLN are made more simple (fewer control-to-management interactions) and more scalable (through the use of aggregated information).
- 在这样的MRN/MLN边缘应用的资源管理和策略变得更简单（更少的控制与管理交互）和更可伸缩（通过使用聚合信息）。
- Multi-region/multi-layer traffic engineering is facilitated as TE links from distinct regions/layers are stored within the same TE Database.
- 由于来自不同区域/层的TE链路存储在同一TE数据库中，因此有助于进行多区域/多层流量工程。
A network comprising transport nodes with multiple data plane layers of either the same ISC or different ISCs, controlled by a single GMPLS control plane instance, is called a multi-layer network (MLN). A subset of MLNs consists of networks supporting LSPs of different switching technologies (ISCs). A network supporting more than one switching technology is called a multi-region network (MRN).
由具有相同ISC或不同ISC的多个数据平面层的传输节点组成的网络，由单个GMPLS控制平面实例控制，称为多层网络（MLN）。MLN的一个子集由支持不同交换技术（ISC）的LSP的网络组成。支持多种交换技术的网络称为多区域网络（MRN）。
The Interface Switching Capability (ISC) is introduced in GMPLS to support various kinds of switching technology in a unified way [RFC4202]. An ISC is identified via a switching type.
GMPLS中引入了接口交换能力（ISC），以统一方式支持各种交换技术[RFC4202]。ISC通过开关类型识别。
A switching type (also referred to as the switching capability type) describes the ability of a node to forward data of a particular data plane technology, and uniquely identifies a network region. The following ISC types (and, hence, regions) are defined: PSC, L2SC, TDM capable, LSC, and FSC. Each end of a data link (more precisely, each interface connecting a data link to a node) in a GMPLS network is associated with an ISC.
交换类型（也称为交换能力类型）描述节点转发特定数据平面技术的数据的能力，并唯一标识网络区域。定义了以下ISC类型（以及相应的区域）：PSC、L2SC、支持TDM、LSC和FSC。GMPLS网络中数据链路的每一端（更准确地说，是将数据链路连接到节点的每个接口）都与ISC相关联。
The ISC value is advertised as a part of the Interface Switching Capability Descriptor (ISCD) attribute (sub-TLV) of a TE link end associated with a particular link interface [RFC4202]. Apart from the ISC, the ISCD contains information including the encoding type, the bandwidth granularity, and the unreserved bandwidth on each of eight priorities at which LSPs can be established. The ISCD does not "identify" network layers, it uniquely characterizes information associated to one or more network layers.
ISC值作为与特定链路接口相关联的TE链路端的接口交换能力描述符（ISCD）属性（子TLV）的一部分发布[RFC4202]。除了ISC之外，ISCD还包含编码类型、带宽粒度和可以建立LSP的八个优先级中的每一个优先级的无保留带宽等信息。ISCD不“识别”网络层，它唯一地描述与一个或多个网络层相关的信息。
TE link end advertisements may contain multiple ISCDs. This can be interpreted as advertising a multi-layer (or multi-switching-capable) TE link end. That is, the TE link end (and therefore the TE link) is present in multiple layers.
TE链路端播发可能包含多个ISCD。这可以解释为宣传多层（或具有多交换能力的）TE链路端。也就是说，TE链路端（因此TE链路）存在于多个层中。
In an MLN, network elements may be single-switching-type-capable or multi-switching-type-capable nodes. Single-switching-type-capable nodes advertise the same ISC value as part of their ISCD sub-TLV(s) to describe the termination capabilities of each of their TE link(s). This case is described in [RFC4202].
在MLN中，网络元件可以是单交换类型能力节点或多交换类型能力节点。具有单一交换类型能力的节点将相同的ISC值作为其ISCD子TLV的一部分进行公布，以描述其每个TE链路的终止能力。[RFC4202]中描述了这种情况。
Multi-switching-type-capable LSRs are classified as "simplex" or "hybrid" nodes. Simplex and hybrid nodes are categorized according to the way they advertise these multiple ISCs:
支持多交换类型的LSR被分类为“单工”或“混合”节点。单工节点和混合节点根据其宣传多个ISC的方式进行分类：
- A simplex node can terminate data links with different switching capabilities where each data link is connected to the node by a separate link interface. So, it advertises several TE links each with a single ISC value carried in its ISCD sub-TLV (following the rules defined in [RFC4206]). An example is an LSR with PSC and TDM links each of which is connected to the LSR via a separate interface.
- 单工节点可以终止具有不同交换能力的数据链路，其中每个数据链路通过单独的链路接口连接到节点。因此，它在其ISCD子TLV（遵循[RFC4206]中定义的规则）中宣传多个TE链接，每个链接都带有一个ISC值。一个例子是具有PSC和TDM链路的LSR，每个链路通过单独的接口连接到LSR。
- A hybrid node can terminate data links with different switching capabilities where the data links are connected to the node by the same interface. So, it advertises a single TE link containing more than one ISCD each with a different ISC value. For example, a node may terminate PSC and TDM data links and interconnect those external data links via internal links. The external interfaces connected to the node have both PSC and TDM capabilities.
- 混合节点可以终止具有不同交换能力的数据链路，其中数据链路通过同一接口连接到节点。因此，它宣传一个包含多个ISCD的TE链接，每个ISC值不同。例如，节点可以终止PSC和TDM数据链路，并通过内部链路互连这些外部数据链路。连接到节点的外部接口具有PSC和TDM功能。
Additionally, TE link advertisements issued by a simplex or a hybrid node may need to provide information about the node's internal adjustment capabilities between the switching technologies supported. The term "adjustment" refers to the property of a hybrid node to interconnect the different switching capabilities that it provides through its external interfaces. The information about the adjustment capabilities of the nodes in the network allows the path computation process to select an end-to-end multi-layer or multi-region path that includes links with different switching capabilities joined by LSRs that can adapt (i.e., adjust) the signal between the links.
此外，由单工或混合节点发布的TE链路广告可能需要提供关于所支持的交换技术之间的节点的内部调整能力的信息。术语“调整”是指混合节点通过其外部接口互连其提供的不同交换能力的特性。关于网络中节点的调整能力的信息允许路径计算过程选择端到端多层或多区域路径，该路径包括由lsr连接的具有不同交换能力的链路，其能够适应（即，调整）链路之间的信号。
This type of network contains at least one hybrid node, zero or more simplex nodes, and a set of single-switching-type-capable nodes.
这种类型的网络包含至少一个混合节点、零个或多个单工节点以及一组具有单交换类型能力的节点。
Figure 1 shows an example hybrid node. The hybrid node has two switching elements (matrices), which support, for instance, TDM and PSC switching, respectively. The node terminates a PSC and a TDM link (Link1 and Link2, respectively). It also has an internal link connecting the two switching elements.
图1显示了一个示例混合节点。混合节点有两个交换元素（矩阵），分别支持TDM和PSC交换。该节点终止PSC和TDM链路（分别为链路1和链路2）。它还有一个连接两个开关元件的内部链路。
The two switching elements are internally interconnected in such a way that it is possible to terminate some of the resources of, say, Link2 and provide adjustment for PSC traffic received/sent over the PSC interface (#b). This situation is modeled in GMPLS by connecting the local end of Link2 to the TDM switching element via an additional interface realizing the termination/adjustment function. There are two possible ways to set up PSC LSPs through the hybrid node. Available resource advertisement (i.e., Unreserved and Min/Max LSP Bandwidth) should cover both of these methods.
这两个交换元件以这样一种方式进行内部互连，即可以终止例如Link2的一些资源，并为通过PSC接口（#b）接收/发送的PSC通信量提供调整。这种情况在GMPLS中建模，通过实现终端/调整功能的附加接口将链路2的本地端连接到TDM开关元件。有两种可能的方法可以通过混合节点设置PSC LSP。可用资源广告（即，无保留和最小/最大LSP带宽）应涵盖这两种方法。
.............................
: Network element :
: -------- :
: | PSC | :
Link1 -------------<->--|#a | :
: | | :
: +--<->---|#b | :
: | -------- :
: | ---------- :
TDM : +--<->--|#c TDM | :
+PSC : | | :
Link2 ------------<->--|#d | :
: ---------- :
:............................
.............................
: Network element :
: -------- :
: | PSC | :
Link1 -------------<->--|#a | :
: | | :
: +--<->---|#b | :
: | -------- :
: | ---------- :
TDM : +--<->--|#c TDM | :
+PSC : | | :
Link2 ------------<->--|#d | :
: ---------- :
:............................
Figure 1. Hybrid node.
图1。混合节点。
In GMPLS-based multi-region/multi-layer networks, TE links may be consolidated into a single Traffic Engineering Database (TED) for use by the single control plane instance. Since this TED contains the information relative to all the layers of all regions in the network, a path across multiple layers (possibly crossing multiple regions) can be computed using the information in this TED. Thus, optimization of network resources across the multiple layers of the same region and across multiple regions can be achieved.
在基于GMPLS的多区域/多层网络中，TE链路可以合并到单个流量工程数据库（TED）中，供单个控制平面实例使用。由于此TED包含与网络中所有区域的所有层相关的信息，因此可以使用此TED中的信息计算跨多个层（可能跨多个区域）的路径。因此，可以实现跨同一区域的多个层和跨多个区域的网络资源优化。
These concepts allow for the operation of one network layer over the topology (that is, TE links) provided by other network layers (for example, the use of a lower-layer LSC LSP carrying PSC LSPs). In turn, a greater degree of control and interworking can be achieved, including (but not limited to):
这些概念允许一个网络层在由其他网络层提供的拓扑（即TE链路）上操作（例如，使用承载PSC LSP的较低层LSC LSP）。反过来，可以实现更大程度的控制和互通，包括（但不限于）：
- Dynamic establishment of Forwarding Adjacency (FA) LSPs [RFC4206] (see Sections 4.3.2 and 4.3.3).
- 动态建立转发邻接（FA）LSP[RFC4206]（见第4.3.2节和第4.3.3节）。
- Provisioning of end-to-end LSPs with dynamic triggering of FA LSPs.
- 通过动态触发FA LSP提供端到端LSP。
Note that in a multi-layer/multi-region network that includes multi-switching-type-capable nodes, an explicit route used to establish an end-to-end LSP can specify nodes that belong to different layers or regions. In this case, a mechanism to control the dynamic creation of FA-LSPs may be required (see Sections 4.3.2 and 4.3.3).
注意，在包括具有多交换类型能力的节点的多层/多区域网络中，用于建立端到端LSP的显式路由可以指定属于不同层或区域的节点。在这种情况下，可能需要一种机制来控制FA LSP的动态创建（见第4.3.2和4.3.3节）。
There is a full spectrum of options to control how FA-LSPs are dynamically established. The process can be subject to the control of a policy, which may be set by a management component and which may require that the management plane is consulted at the time that the FA-LSP is established. Alternatively, the FA-LSP can be established at the request of the control plane without any management control.
有一整套选项可用于控制如何动态建立FA LSP。该过程可受政策控制，该政策可由管理部门设定，并要求在建立FA-LSP时咨询管理层。或者，可以根据控制平面的请求建立FA-LSP，而无需任何管理控制。
When an LSP crosses the boundary from an upper to a lower layer, it may be nested into a lower-layer FA-LSP that crosses the lower layer. From a signaling perspective, there are two alternatives to establish the lower-layer FA-LSP: static (pre-provisioned) and dynamic (triggered). A pre-provisioned FA-LSP may be initiated either by the operator or automatically using features like TE auto-mesh [RFC4972]. If such a lower-layer LSP does not already exist, the LSP may be established dynamically. Such a mechanism is referred to as "triggered signaling".
当LSP从上层穿过边界到下层时，它可以嵌套到穿过下层的下层FA-LSP中。从信令的角度来看，有两种方法可以建立较低层的FA-LSP：静态（预配置）和动态（触发）。预配置的FA-LSP可以由操作员启动，也可以使用TE auto mesh[RFC4972]等功能自动启动。如果这样的较低层LSP不存在，则可以动态地建立LSP。这种机制被称为“触发信令”。
Once an LSP is created across a layer from one layer border node to another, it can be used as a data link in an upper layer.
一旦跨层创建了从一个层边界节点到另一个层边界节点的LSP，它就可以用作上层的数据链路。
Furthermore, it can be advertised as a TE link, allowing other nodes to consider the LSP as a TE link for their path computation [RFC4206]. An LSP created either statically or dynamically by one instance of the control plane and advertised as a TE link into the same instance of the control plane is called a Forwarding Adjacency LSP (FA-LSP). The FA-LSP is advertised as a TE link, and that TE link is called a Forwarding Adjacency (FA). An FA has the special
此外，它可以被广告为TE链路，允许其他节点考虑LSP作为TE链路用于它们的路径计算[RCF4206]。由控制平面的一个实例静态或动态创建并作为TE链路播发到控制平面的同一实例的LSP称为转发邻接LSP（FA-LSP）。FA-LSP被广告为TE链路，该TE链路被称为转发邻接（FA）。安总有特殊的职责
characteristic of not requiring a routing adjacency (peering) between its end points yet still guaranteeing control plane connectivity between the FA-LSP end points based on a signaling adjacency. An FA is a useful and powerful tool for improving the scalability of GMPLS-TE capable networks since multiple higher-layer LSPs may be nested (aggregated) over a single FA-LSP.
在其端点之间不需要路由邻接（对等），但仍然基于信令邻接保证FA-LSP端点之间的控制平面连接的特性。FA是提高支持GMPLS-TE的网络可伸缩性的有用且强大的工具，因为多个高层LSP可以嵌套（聚合）在单个FA-LSP上。
The aggregation of LSPs enables the creation of a vertical (nested) LSP hierarchy. A set of FA-LSPs across or within a lower layer can be used during path selection by a higher-layer LSP. Likewise, the higher-layer LSPs may be carried over dynamic data links realized via LSPs (just as they are carried over any "regular" static data links). This process requires the nesting of LSPs through a hierarchical process [RFC4206]. The TED contains a set of LSP advertisements from different layers that are identified by the ISCD contained within the TE link advertisement associated with the LSP [RFC4202].
LSP的聚合支持创建垂直（嵌套）LSP层次结构。跨低层或在低层内的一组FA LSP可在高层LSP的路径选择期间使用。类似地，更高层lsp可以通过通过lsp实现的动态数据链路承载（就像它们通过任何“常规”静态数据链路承载一样）。此过程需要通过分层过程嵌套LSP[RFC4206]。TED包含来自不同层的一组LSP播发，这些层由与LSP相关联的TE链路播发中包含的ISCD标识[RFC4202]。
If a lower-layer LSP is not advertised as an FA, it can still be used to carry higher-layer LSPs across the lower layer. For example, if the LSP is set up using triggered signaling, it will be used to carry the higher-layer LSP that caused the trigger. Further, the lower layer remains available for use by other higher-layer LSPs arriving at the boundary.
如果较低层LSP未作为FA进行广告，则它仍然可以用于在较低层上承载较高层LSP。例如，如果使用触发信令设置LSP，则它将用于承载导致触发的更高层LSP。此外，下层仍然可供到达边界的其他高层LSP使用。
Under some circumstances, it may be useful to control the advertisement of LSPs as FAs during the signaling establishment of the LSPs [DYN-HIER].
在某些情况下，在lsp的信令建立期间控制lsp作为FAs的广告可能是有用的[DYN-HIER]。
A set of one or more lower-layer LSPs provides information for efficient path handling in upper layer(s) of the MLN, or, in other words, provides a virtual network topology (VNT) to the upper layers. For instance, a set of LSPs, each of which is supported by an LSC LSP, provides a VNT to the layers of a PSC region, assuming that the PSC region is connected to the LSC region. Note that a single lower-layer LSP is a special case of the VNT. The VNT is configured by setting up or tearing down the lower-layer LSPs. By using GMPLS signaling and routing protocols, the VNT can be adapted to traffic demands.
一个或多个较低层lsp的集合提供用于在MLN的较高层中的有效路径处理的信息，或者换句话说，向较高层提供虚拟网络拓扑（VNT）。例如，假设PSC区域连接到LSC区域，则一组LSP（每个LSP都由LSC LSP支持）向PSC区域的层提供VNT。请注意，单个下层LSP是VNT的特例。通过设置或拆除下层LSP来配置VNT。通过使用GMPLS信令和路由协议，VNT可以适应业务需求。
A lower-layer LSP appears as a TE link in the VNT. Whether the diversely-routed lower-layer LSPs are used or not, the routes of lower-layer LSPs are hidden from the upper layer in the VNT. Thus, the VNT simplifies the upper-layer routing and traffic engineering decisions by hiding the routes taken by the lower-layer LSPs. However, hiding the routes of the lower-layer LSPs may lose important information that is needed to make the higher-layer LSPs reliable.
下层LSP在VNT中显示为TE链路。无论是否使用不同路由的下层LSP，下层LSP的路由在VNT中对上层隐藏。因此，VNT通过隐藏下层lsp采取的路由来简化上层路由和流量工程决策。然而，隐藏较低层lsp的路由可能丢失使较高层lsp可靠所需的重要信息。
For instance, the routing and traffic engineering in the IP/MPLS layer does not usually consider how the IP/MPLS TE links are formed from optical paths that are routed in the fiber layer. Two optical paths may share the same fiber link in the lower-layer and therefore they may both fail if the fiber link is cut. Thus the shared risk properties of the TE links in the VNT must be made available to the higher layer during path computation. Further, the topology of the VNT should be designed so that any single fiber cut does not bisect the VNT. These issues are addressed later in this document.
例如，IP/MPLS层中的路由和流量工程通常不考虑IP/MPLS TE链路是如何由在光纤层中路由的光路形成的。两条光路可能在较低层共享同一光纤链路，因此，如果光纤链路被切断，它们都可能发生故障。因此，在路径计算期间，必须使VNT中TE链路的共享风险特性可供更高层使用。此外，VNT的拓扑结构设计应确保任何单光纤切割不会将VNT平分。本文件后面将讨论这些问题。
Reconfiguration of the VNT may be triggered by traffic demand changes, topology configuration changes, signaling requests from the upper layer, and network failures. For instance, by reconfiguring the VNT according to the traffic demand between source and destination node pairs, network performance factors, such as maximum link utilization and residual capacity of the network, can be optimized. Reconfiguration is performed by computing the new VNT from the traffic demand matrix and optionally from the current VNT. Exact details are outside the scope of this document. However, this method may be tailored according to the service provider's policy regarding network performance and quality of service (delay, loss/disruption, utilization, residual capacity, reliability).
VNT的重新配置可由业务需求变化、拓扑结构变化、来自上层的信令请求和网络故障触发。例如，通过根据源节点对和目的节点对之间的业务需求重新配置VNT，可以优化网络性能因素，例如最大链路利用率和网络的剩余容量。通过从流量需求矩阵和可选地从当前VNT计算新VNT来执行重新配置。具体细节不在本文件范围内。然而，该方法可以根据服务提供商关于网络性能和服务质量（延迟、丢失/中断、利用率、剩余容量、可靠性）的政策进行定制。
The MRN/MLN can consist of single-switching-type-capable and multi-switching-type-capable nodes. The path computation mechanism in the MLN should be able to compute paths consisting of any combination of such nodes.
MRN/MLN可以由支持单交换类型和支持多交换类型的节点组成。MLN中的路径计算机制应该能够计算由这些节点的任意组合组成的路径。
Both single-switching-type-capable and multi-switching-type-capable (simplex or hybrid) nodes could play the role of layer boundary. MRN/MLN path computation should handle TE topologies built of any combination of nodes.
无论是单交换型节点还是多交换型节点（单工或混合）都可以扮演层边界的角色。MRN/MLN路径计算应处理由任意节点组合构建的TE拓扑。
A hybrid node should maintain resources on its internal links (the links required for vertical integration between layers). Likewise, path computation elements should be prepared to use information about the availability of termination and adjustment resources as a constraint in MRN/MLN path computations. This would reduce the probability that the setup of the higher-layer LSP will be blocked by the lack of necessary termination/adjustment resources in the lower layers.
混合节点应在其内部链接（层间垂直集成所需的链接）上维护资源。同样，路径计算元素应准备好使用有关终止和调整资源可用性的信息作为MRN/MLN路径计算中的约束。这将降低较高层LSP的设置因较低层中缺乏必要的终止/调整资源而受阻的可能性。
The advertisement of a node's MRN adjustment capabilities (the ability to terminate LSPs of lower regions and forward the traffic in upper regions) is REQUIRED, as it provides critical information when performing multi-region path computation.
需要公布节点的MRN调整能力（终止较低区域的LSP和转发较高区域的流量的能力），因为它在执行多区域路径计算时提供关键信息。
The path computation mechanism should cover the case where the upper-layer links that are directly connected to upper-layer switching elements and the ones that are connected through internal links between upper-layer element and lower-layer element coexist (see Section 4.2.1).
路径计算机制应涵盖直接连接到上层交换元件的上层链路与通过上层元件和下层元件之间的内部链路连接的上层链路共存的情况（见第4.2.1节）。
The MRN/MLN relies on unified routing and traffic engineering models.
MRN/MLN依赖于统一的路由和流量工程模型。
- Unified routing model: By maintaining a single routing protocol instance and a single TE database per LSR, a unified control plane model removes the requirement to maintain a dedicated routing topology per layer, and therefore does not mandate a full mesh of routing adjacencies per layer.
- 统一路由模型：通过为每个LSR维护一个路由协议实例和一个TE数据库，统一控制平面模型消除了维护每层专用路由拓扑的要求，因此不要求每层有完整的路由邻接网格。
- Unified TE model: The TED in each LSR is populated with TE links from all layers of all regions (TE link interfaces on multiple-switching-type-capable LSRs can be advertised with multiple ISCDs). This may lead to an increase in the amount of information that has to be flooded and stored within the network.
- 统一TE模型：每个LSR中的TED由来自所有区域的所有层的TE链路填充（多个支持交换类型的LSR上的TE链路接口可以用多个ISCD播发）。这可能导致网络中必须被淹没和存储的信息量增加。
Furthermore, path computation times, which may be of great importance during restoration, will depend on the size of the TED.
此外，路径计算时间（在恢复期间可能非常重要）将取决于TED的大小。
Thus, MRN/MLN routing mechanisms MUST be designed to scale well with an increase of any of the following:
因此，MRN/MLN路由机制的设计必须能够随着以下任何一项的增加而很好地扩展：
- Number of nodes - Number of TE links (including FA-LSPs) - Number of LSPs - Number of regions and layers - Number of ISCDs per TE link.
- 节点数-TE链路数（包括FA LSP）-LSP数-区域和层数-每个TE链路的ISCD数。
Further, design of the routing protocols MUST NOT prevent TE information filtering based on ISCDs. The path computation mechanism and the signaling protocol SHOULD be able to operate on partial TE information.
此外，路由协议的设计不能阻止基于ISCDs的TE信息过滤。路径计算机制和信令协议应能够对部分TE信息进行操作。
Since TE links can advertise multiple Interface Switching Capabilities (ISCs), the number of links can be limited (by combination) by using specific topological maps referred to as VNTs
由于TE链路可以宣传多个接口交换功能（ISC），因此可以通过使用称为VNT的特定拓扑图来限制链路的数量（通过组合）
(Virtual Network Topologies). The introduction of virtual topological maps leads us to consider the concept of emulation of data plane overlays.
（虚拟网络拓扑）。虚拟拓扑图的引入使我们考虑了数据平面覆盖的仿真概念。
Path computation is dependent on the network topology and associated link state. The path computation stability of an upper layer may be impaired if the VNT changes frequently and/or if the status and TE parameters (the TE metric, for instance) of links in the VNT changes frequently. In this context, robustness of the VNT is defined as the capability to smooth changes that may occur and avoid their propagation into higher layers. Changes to the VNT may be caused by the creation, deletion, or modification of LSPs.
路径计算取决于网络拓扑和相关链路状态。如果VNT频繁改变和/或如果VNT中的链路的状态和TE参数（例如TE度量）频繁改变，则上层的路径计算稳定性可能受损。在此上下文中，VNT的健壮性定义为平滑可能发生的更改并避免其传播到更高层的能力。对VNT的更改可能是由LSP的创建、删除或修改引起的。
Protocol mechanisms MUST be provided to enable creation, deletion, and modification of LSPs triggered through operational actions. Protocol mechanisms SHOULD be provided to enable similar functions triggered by adjacent layers. Protocol mechanisms MAY be provided to enable similar functions to adapt to the environment changes such as traffic demand changes, topology changes, and network failures. Routing robustness should be traded with adaptability of those changes.
必须提供协议机制，以支持通过操作操作触发的LSP的创建、删除和修改。应提供协议机制，以实现由相邻层触发的类似功能。可以提供协议机制以使类似功能能够适应环境变化，例如业务需求变化、拓扑变化和网络故障。路由稳健性应该与这些变化的适应性进行权衡。
When reconfiguring the VNT according to a change in traffic demand, the upper-layer LSP might be disrupted. Such disruption to the upper layers must be minimized.
当根据业务需求的变化重新配置VNT时，上层LSP可能会中断。必须尽量减少对上层的破坏。
When residual resource decreases to a certain level, some lower-layer LSPs may be released according to local or network policies. There is a trade-off between minimizing the amount of resource reserved in the lower layer and disrupting higher-layer traffic (i.e., moving the traffic to other TE-LSPs so that some LSPs can be released). Such traffic disruption may be allowed, but MUST be under the control of policy that can be configured by the operator. Any repositioning of traffic MUST be as non-disruptive as possible (for example, using make-before-break).
当剩余资源减少到一定程度时，可以根据本地或网络策略释放一些下层LSP。在最小化低层中保留的资源量和中断高层通信量（即，将通信量移动到其他TE lsp以便可以释放一些lsp）之间存在权衡。这种交通中断可能是允许的，但必须在运营商可以配置的策略的控制下。流量的任何重新定位必须尽可能无中断（例如，使用先通后断）。
TE link parameters should be inherited from the parameters of the LSP that provides the TE link, and so from the TE links in the lower layer that are traversed by the LSP.
TE链路参数应继承自提供TE链路的LSP的参数，也应继承自LSP遍历的较低层中的TE链路。
These include:
这些措施包括：
- Interface Switching Capability - TE metric - Maximum LSP bandwidth per priority level - Unreserved bandwidth for all priority levels - Maximum reservable bandwidth - Protection attribute - Minimum LSP bandwidth (depending on the switching capability) - SRLG
- 接口交换能力-TE指标-每个优先级的最大LSP带宽-所有优先级的无保留带宽-最大可保留带宽-保护属性-最小LSP带宽（取决于交换能力）-SRLG
Inheritance rules must be applied based on specific policies. Particular attention should be given to the inheritance of the TE metric (which may be other than a strict sum of the metrics of the component TE links at the lower layer), protection attributes, and SRLG.
继承规则必须基于特定的策略应用。应特别注意TE度量（可能不是较低层组件TE链路度量的严格总和）、保护属性和SRLG的继承。
As described earlier, hiding the routes of the lower-layer LSPs may lose important information necessary to make LSPs in the higher-layer network reliable. SRLGs may be used to identify which lower-layer LSPs share the same failure risk so that the potential risk of the VNT becoming disjoint can be minimized, and so that resource-disjoint protection paths can be set up in the higher layer. How to inherit the SRLG information from the lower layer to the upper layer needs more discussion and is out of scope of this document.
如前所述，隐藏较低层lsp的路由可能丢失使较高层网络中的lsp可靠所必需的重要信息。srlg可用于识别哪些较低层lsp共享相同的故障风险，以便可以最小化VNT变得不相交的潜在风险，并且使得可以在较高层中建立资源不相交保护路径。如何将SRLG信息从底层继承到上层需要更多的讨论，不在本文档的范围内。
Path computation can take into account LSP region and layer boundaries when computing a path for an LSP. Path computation may restrict the path taken by an LSP to only the links whose interface switching capability is PSC. For example, suppose that a TDM-LSP is routed over the topology composed of TE links of the same TDM layer. In calculating the path for the LSP, the TED may be filtered to include only links where both end include requested LSP switching type. In this way hierarchical routing is done by using a TED filtered with respect to switching capability (that is, with respect to particular layer).
在计算LSP的路径时，路径计算可以考虑LSP区域和层边界。路径计算可将LSP所采用的路径限制为仅其接口交换能力为PSC的链路。例如，假设TDM-LSP在由相同TDM层的TE链路组成的拓扑上路由。在计算LSP的路径时，可以过滤TED以仅包括两端都包括请求的LSP交换类型的链路。以这种方式，分层路由通过使用针对交换能力（即，针对特定层）过滤的TED来完成。
If triggered signaling is allowed, the path computation mechanism may produce a route containing multiple layers/regions. The path is computed over the multiple layers/regions even if the path is not "connected" in the same layer as where the endpoints of the path exist. Note that here we assume that triggered signaling will be invoked to make the path "connected", when the upper-layer signaling request arrives at the boundary node.
如果允许触发信令，则路径计算机制可产生包含多个层/区域的路由。在多个层/区域上计算路径，即使路径与路径的端点不在同一层中“连接”。注意，这里我们假设当上层信令请求到达边界节点时，将调用触发的信令以使路径“连接”。
The upper-layer signaling request MAY contain an ERO (Explicit Route Object) that includes only hops in the upper layer; in which case, the boundary node is responsible for triggered creation of the lower-layer FA-LSP using a path of its choice, or for the selection of any available lower-layer LSP as a data link for the higher layer. This mechanism is appropriate for environments where the TED is filtered in the higher layer, where separate routing instances are used per layer, or where administrative policies prevent the higher layer from specifying paths through the lower layer.
上层信令请求可以包含仅包括上层中的跳的ERO（显式路由对象）；在这种情况下，边界节点负责使用其选择的路径触发创建下层FA-LSP，或负责选择任何可用的下层LSP作为上层的数据链路。此机制适用于在较高层过滤TED、在每层使用单独的路由实例或管理策略阻止较高层指定通过较低层的路径的环境。
Obviously, if the lower-layer LSP has been advertised as a TE link (virtual or real) into the higher layer, then the higher-layer signaling request MAY contain the TE link identifier and so indicate the lower-layer resources to be used. But in this case, the path of the lower-layer LSP can be dynamically changed by the lower layer at any time.
显然，如果较低层LSP已被作为TE链路（虚拟或真实）播发到较高层，则较高层信令请求可包含TE链路标识符，从而指示要使用的较低层资源。但是在这种情况下，下层LSP的路径可以随时由下层动态地改变。
Alternatively, the upper-layer signaling request MAY contain an ERO specifying the lower-layer FA-LSP route. In this case, the boundary node MAY decide whether it should use the path contained in the strict ERO or re-compute the path within the lower layer.
或者，上层信令请求可以包含指定下层FA-LSP路由的ERO。在这种情况下，边界节点可以决定是使用严格ERO中包含的路径，还是在较低层内重新计算路径。
Even in the case that the lower-layer FA-LSPs are already established, a signaling request may also be encoded as a loose ERO. In this situation, it is up to the boundary node to decide whether it should create a new lower-layer FA-LSP or it should use an existing lower-layer FA-LSP.
即使在较低层FA lsp已经建立的情况下，信令请求也可以被编码为松散的ERO。在这种情况下，由边界节点决定是创建新的较低层FA-LSP，还是使用现有的较低层FA-LSP。
The lower-layer FA-LSP can be advertised just as an FA-LSP in the upper layer or an IGP adjacency can be brought up on the lower-layer FA-LSP.
下层FA-LSP可以像上层中的FA-LSP一样进行广告，或者可以在下层FA-LSP上显示IGP邻接。
Resource usage in all layers should be optimized as a whole (i.e., across all layers), in a coordinated manner (i.e., taking all layers into account). The number of lower-layer LSPs carrying upper-layer LSPs should be minimized (note that multiple LSPs may be used for load balancing). Lower-layer LSPs that could have their traffic re-routed onto other LSPs are unnecessary and should be avoided.
所有层中的资源使用应以协调的方式（即考虑到所有层）作为一个整体进行优化（即跨所有层）。应尽量减少承载上层LSP的下层LSP的数量（注意，多个LSP可用于负载平衡）。可以将其流量重新路由到其他LSP的较低层LSP是不必要的，应该避免。
If there is low traffic demand, some FA-LSPs that do not carry any higher-layer LSP may be released so that lower-layer resources are released and can be assigned to other uses. Note that if a small fraction of the available bandwidth of an FA-LSP is still in use, the nested LSPs can also be re-routed to other FA-LSPs (optionally using
如果存在低流量需求，则可以释放一些不携带任何更高层LSP的FA LSP，以便释放较低层资源并可以将其分配给其他用途。请注意，如果FA-LSP的可用带宽的一小部分仍在使用中，则嵌套LSP也可以重新路由到其他FA-LSP（可选地使用
the make-before-break technique) to completely free up the FA-LSP. Alternatively, unused FA-LSPs may be retained for future use. Release or retention of underutilized FA-LSPs is a policy decision.
先通后断技术）以完全释放FA-LSP。或者，可以保留未使用的FA LSP以备将来使用。释放或保留未充分利用的FA LSP是一项政策决策。
As part of the re-optimization process, the solution MUST allow rerouting of an FA-LSP while keeping interface identifiers of corresponding TE links unchanged. Further, this process MUST be possible while the FA-LSP is carrying traffic (higher-layer LSPs) with minimal disruption to the traffic.
作为重新优化过程的一部分，解决方案必须允许FA-LSP的重新路由，同时保持相应TE链路的接口标识符不变。此外，当FA-LSP承载流量（更高层LSP）时，该过程必须是可能的，且对流量的干扰最小。
Additional FA-LSPs may also be created based on policy, which might consider residual resources and the change of traffic demand across the region. By creating the new FA-LSPs, the network performance such as maximum residual capacity may increase.
另外的FA LSP也可以基于政策创建，这可能考虑剩余资源和跨区域的交通需求的变化。通过创建新的FA lsp，可以提高网络性能，例如最大剩余容量。
As the number of FA-LSPs grows, the residual resources may decrease. In this case, re-optimization of FA-LSPs may be invoked according to policy.
随着FA lsp数量的增加，剩余资源可能会减少。在这种情况下，可以根据策略调用FA lsp的重新优化。
Any solution MUST include measures to protect against network destabilization caused by the rapid setup and teardown of LSPs as traffic demand varies near a threshold.
任何解决方案都必须包括防止LSP快速设置和拆除导致网络不稳定的措施，因为流量需求在阈值附近变化。
Signaling of lower-layer LSPs SHOULD include a mechanism to rapidly advertise the LSP as a TE link and to coordinate into which routing instances the TE link should be advertised.
较低层LSP的信令应包括一种机制，用于将LSP作为TE链路快速通告，并协调TE链路应通告到哪些路由实例中。
It may be considered disadvantageous to fully instantiate (i.e., pre-provision) the set of lower-layer LSPs that provide the VNT since this might reserve bandwidth that could be used for other LSPs in the absence of upper-layer traffic.
可以认为完全实例化（即，预先提供）提供VNT的低层lsp的集合是不利的，因为这可能保留在没有上层业务的情况下可用于其他lsp的带宽。
However, in order to allow path computation of upper-layer LSPs across the lower layer, the lower-layer LSPs may be advertised into the upper layer as though they had been fully established, but without actually establishing them. Such TE links that represent the possibility of an underlying LSP are termed "virtual TE links". It is an implementation choice at a layer boundary node whether to create real or virtual TE links, and the choice (if available in an implementation) MUST be under the control of operator policy. Note that there is no requirement to support the creation of virtual TE links, since real TE links (with established LSPs) may be used. Even if there are no TE links (virtual or real) advertised to the higher layer, it is possible to route a higher-layer LSP into a lower layer on the assumption that proper hierarchical LSPs in the lower layer will be dynamically created (triggered) as needed.
然而，为了允许跨较低层的上层lsp的路径计算，可以将较低层lsp播发到上层，如同它们已经完全建立，但是没有实际建立它们。这种表示潜在LSP可能性的TE链路被称为“虚拟TE链路”。创建真实或虚拟TE链路是层边界节点的实现选择，该选择（如果在实现中可用）必须在操作员策略的控制下。注意，不需要支持创建虚拟TE链路，因为可以使用真实TE链路（具有已建立的LSP）。即使不存在向较高层通告的TE链路（虚拟或真实），也可以将较高层LSP路由到较低层，前提是将根据需要动态创建（触发）较低层中的适当分层LSP。
If an upper-layer LSP that makes use of a virtual TE link is set up, the underlying LSP MUST be immediately signaled in the lower layer.
如果设置了使用虚拟TE链路的上层LSP，则必须立即在下层用信号通知底层LSP。
If virtual TE links are used in place of pre-established LSPs, the TE links across the upper layer can remain stable using pre-computed paths while wastage of bandwidth within the lower layer and unnecessary reservation of adaptation resources at the border nodes can be avoided.
如果使用虚拟TE链路代替预先建立的lsp，则上层的TE链路可以使用预先计算的路径保持稳定，同时可以避免下层内的带宽浪费和边界节点处不必要的自适应资源保留。
The solution SHOULD provide operations to facilitate the build-up of such virtual TE links, taking into account the (forecast) traffic demand and available resources in the lower layer.
该解决方案应提供操作，以促进此类虚拟TE链路的建立，同时考虑（预测）流量需求和较低层的可用资源。
Virtual TE links can be added, removed, or modified dynamically (by changing their capacity) according to the change of the (forecast) traffic demand and the available resources in the lower layer. It MUST be possible to add, remove, and modify virtual TE links in a dynamic way.
虚拟TE链路可以根据（预测）流量需求和下层可用资源的变化动态添加、删除或修改（通过更改其容量）。必须能够以动态方式添加、删除和修改虚拟TE链接。
Any solution MUST include measures to protect against network destabilization caused by the rapid changes in the VNT as traffic demand varies near a threshold.
任何解决方案都必须包括防止VNT快速变化导致网络不稳定的措施，因为流量需求在阈值附近变化。
The concept of the VNT can be extended to allow the virtual TE links to form part of the VNT. The combination of the fully provisioned TE links and the virtual TE links defines the VNT provided by the lower layer. The VNT can be changed by setting up and/or tearing down virtual TE links as well as by modifying real links (i.e., the fully provisioned LSPs). How to design the VNT and how to manage it are out of scope of this document.
VNT的概念可以扩展为允许虚拟TE链接构成VNT的一部分。完全配置的TE链路和虚拟TE链路的组合定义了由较低层提供的VNT。可以通过设置和/或拆除虚拟TE链路以及修改真实链路（即，完全配置的LSP）来更改VNT。如何设计VNT以及如何管理VNT超出了本文档的范围。
In some situations, selective advertisement of the preferred connectivity among a set of border nodes between layers may be appropriate. Further decreasing the number of advertisements of the virtual connectivity can be achieved by abstracting the topology (between border nodes) using models similar to those detailed in [RFC4847].
在一些情况下，层之间的一组边界节点之间的优选连接性的选择性广告可能是合适的。通过使用类似于[RFC4847]中详述的模型抽象拓扑（边界节点之间），可以进一步减少虚拟连接的广告数量。
When a lower-layer LSP is established for use as a data link by a higher layer, the LSP may be verified for correct connectivity and data integrity before it is made available for use. Such mechanisms are data-technology-specific and are beyond the scope of this document, but the GMPLS protocols SHOULD provide mechanisms for the coordination of data link verification.
当较低层LSP被建立以供较高层用作数据链路时，可以在LSP可供使用之前验证其正确的连接性和数据完整性。此类机制是特定于数据技术的，超出了本文件的范围，但GMPLS协议应提供协调数据链路验证的机制。
An MRN/MLN requires management capabilities. Operators need to have the same level of control and management for switches and links in the network that they would have in a single-layer or single-region network.
MRN/MLN需要管理能力。运营商需要对网络中的交换机和链路进行与在单层或单区域网络中相同的控制和管理。
We can consider two different operational models: (1) per-layer management entities and (2) cross-layer management entities.
我们可以考虑两种不同的操作模型：（1）每层管理实体和（2）跨层管理实体。
Regarding per-layer management entities, it is possible for the MLN to be managed entirely as separate layers, although that somewhat defeats the objective of defining a single multi-layer network. In this case, separate management systems would be operated for each layer, and those systems would be unaware of the fact that the layers were closely coupled in the control plane. In such a deployment, as LSPs were automatically set up as the result of control plane requests from other layers (for example, triggered signaling), the management applications would need to register the creation of the new LSPs and the depletion of network resources. Emphasis would be placed on the layer boundary nodes to report the activity to the management applications.
关于每层管理实体，MLN可以完全作为单独的层进行管理，尽管这在一定程度上违背了定义单个多层网络的目标。在这种情况下，将为每个层操作单独的管理系统，这些系统将不知道这些层在控制平面中紧密耦合的事实。在这种部署中，由于lsp是由于来自其他层的控制平面请求（例如，触发的信令）而自动设置的，因此管理应用程序将需要注册新lsp的创建和网络资源的消耗。重点将放在层边界节点上，以向管理应用程序报告活动。
A more likely scenario is to apply a closer coupling of layer management systems with cross-layer management entities. This might be achieved through a unified management system capable of operating multiple layers, or by a meta-management system that coordinates the operation of separate management systems each responsible for individual layers. The former case might only be possible with the development of new management systems, while the latter is feasible through the coordination of existing network management tools.
一个更可能的场景是应用层管理系统与跨层管理实体的更紧密耦合。这可以通过一个能够操作多个层的统一管理系统来实现，或者通过一个元管理系统来实现，该元管理系统协调每个层负责的单独管理系统的操作。前一种情况可能只有在开发新的管理系统时才可能出现，而后一种情况是通过协调现有的网络管理工具才可行的。
Note that when a layer boundary also forms an administrative boundary, it is highly unlikely that there will be unified multi-layer management. In this case, the layers will be separately managed by the separate administrative entities, but there may be some "leakage" of information between the administrations in order to facilitate the operation of the MLN. For example, the management system in the lower-layer network might automatically issue reports on resource availability (coincident with TE routing information) and alarm events.
请注意，当层边界也形成管理边界时，很可能不存在统一的多层管理。在这种情况下，各层将由单独的行政实体单独管理，但行政部门之间可能存在一些信息“泄漏”，以便于MLN的运作。例如，较低层网络中的管理系统可能会自动发布关于资源可用性（与TE路由信息一致）和警报事件的报告。
This discussion comes close to an examination of how a VNT might be managed and operated. As noted in Section 5.8, issues of how to design and manage a VNT are out of scope for this document, but it should be understood that the VNT is a client-layer construct built from server-layer resources. This means that the operation of a VNT
这一讨论接近于对如何管理和操作VNT的检查。如第5.8节所述，如何设计和管理VNT的问题超出了本文档的范围，但应该理解的是，VNT是从服务器层资源构建的客户端层构造。这意味着VNT的操作
is a collaborative activity between layers. This activity is possible even if the layers are from separate administrations, but in this case the activity may also have commercial implications.
是层之间的协作活动。即使各层来自不同的管理部门，该活动也是可能的，但在这种情况下，该活动也可能具有商业意义。
MIB modules exist for the modeling and management of GMPLS networks [RFC4802] [RFC4803]. Some deployments of GMPLS networks may choose to use MIB modules to operate individual network layers. In these cases, operators may desire to coordinate layers through a further MIB module that could be developed. Multi-layer protocol solutions (that is, solutions where a single control plane instance operates in more than one layer) SHOULD be manageable through MIB modules. A further MIB module to coordinate multiple network layers with this control plane MIB module may be produced.
MIB模块用于GMPLS网络的建模和管理[RFC4802][RFC4803]。GMPLS网络的某些部署可能会选择使用MIB模块来操作各个网络层。在这些情况下，操作员可能希望通过可以开发的另一个MIB模块来协调层。多层协议解决方案（即单个控制平面实例在多个层中运行的解决方案）应通过MIB模块进行管理。可以产生另一MIB模块，用于与该控制平面MIB模块协调多个网络层。
Operations and Management (OAM) tools are important to the successful deployment of all networks.
操作和管理（OAM）工具对于所有网络的成功部署非常重要。
OAM requirements for GMPLS networks are described in [GMPLS-OAM]. That document points out that protocol solutions for individual network layers should include mechanisms for OAM or make use of OAM features inherent in the physical media of the layers. Further discussion of individual-layer OAM is out of scope of this document.
GMPLS网络的OAM要求见[GMPLS-OAM]。该文件指出，各个网络层的协议解决方案应包括OAM机制，或利用各层物理介质固有的OAM特性。对各层OAM的进一步讨论超出了本文档的范围。
When operating OAM in a MLN, consideration must be given to how to provide OAM for end-to-end LSPs that cross layer boundaries (that may also be administrative boundaries) and how to coordinate errors and alarms detected in a server layer that need to be reported to the client layer. These operational choices MUST be left open to the service provider and so MLN protocol solutions MUST include the following features:
在MLN中操作OAM时，必须考虑如何为跨层边界（也可能是管理边界）的端到端LSP提供OAM，以及如何协调服务器层中检测到的需要报告给客户端层的错误和警报。这些操作选择必须留给服务提供商，因此MLN协议解决方案必须包括以下功能：
- Within the context and technology capabilities of the highest technology layer of an LSP (i.e., the technology layer of the first hop), it MUST be possible to enable end-to-end OAM on a MLN LSP. This function appears to the ingress LSP as normal LSP-based OAM [GMPLS-OAM], but at layer boundaries, depending on the technique used to span the lower layers, client-layer OAM operations may need to mapped to server-layer OAM operations. Most such requirements are highly dependent on the OAM facilities of the data plane technologies of client and server layers. However, control plane mechanisms used in the client layer per [GMPLS-OAM] MUST map and enable OAM in the server layer.
- 在LSP的最高技术层（即，第一跳的技术层）的上下文和技术能力内，必须能够在MLN LSP上启用端到端OAM。入口LSP将此功能视为基于LSP的普通OAM[GMPLS-OAM]，但在层边界处，根据用于跨越较低层的技术，客户端层OAM操作可能需要映射到服务器层OAM操作。大多数此类需求高度依赖于客户端和服务器层的数据平面技术的OAM设施。但是，客户机层per[GMPLS-OAM]中使用的控制平面机制必须映射并启用服务器层中的OAM。
- OAM operation enabled per [GMPLS-OAM] in a client layer for an LSP MUST operate for that LSP along its entire length. This means that if an LSP crosses a domain of a lower-layer technology, the client-layer OAM operation must operate seamlessly within the client layer at both ends of the client-layer LSP.
- LSP客户端层中根据[GMPLS-OAM]启用的OAM操作必须在该LSP的整个长度上运行。这意味着，如果LSP跨越较低层技术的域，则客户端层OAM操作必须在客户端层LSP两端的客户端层内无缝操作。
- OAM functions operating within a server layer MUST be controllable from the client layer such that the server-layer LSP(s) that support a client-layer LSP have OAM enabled at the request of the client layer. Such control SHOULD be subject to policy at the layer boundary, just as automatic provisioning and LSP requests to the server layer are subject to policy.
- 在服务器层内运行的OAM功能必须可以从客户端层进行控制，以便支持客户端层LSP的服务器层LSP在客户端层的请求下启用OAM。这种控制应该受层边界策略的约束，就像自动资源调配和对服务器层的LSP请求受策略约束一样。
- The status including errors and alarms applicable to a server-layer LSP MUST be available to the client layer. This information SHOULD be configurable to be automatically notified to the client layer at the layer boundary and SHOULD be subject to policy so that the server layer may filter or hide information supplied to the client layer. Furthermore, the client layer SHOULD be able to select to not receive any or all such information.
- 适用于服务器层LSP的状态（包括错误和警报）必须可用于客户端层。该信息应可配置为在层边界处自动通知客户端层，并应遵守策略，以便服务器层可以过滤或隐藏提供给客户端层的信息。此外，客户端层应该能够选择不接收任何或所有此类信息。
Note that the interface between layers lies within network nodes and is, therefore, not necessarily the subject of a protocol specification. Implementations MAY use standardized techniques (such as MIB modules) to convey status information (such as errors and alarms) between layers, but that is out of scope for this document.
注意，层之间的接口位于网络节点内，因此不一定是协议规范的主题。实现可以使用标准化技术（如MIB模块）在层之间传递状态信息（如错误和警报），但这超出了本文档的范围。
The MLN/MRN architecture does not introduce any new security requirements over the general GMPLS architecture described in [RFC3945]. Additional security considerations form MPLS and GMPLS networks are described in [MPLS-SEC].
MLN/MRN体系结构与[RFC3945]中描述的通用GMPLS体系结构相比，没有引入任何新的安全要求。[MPLS-SEC]中描述了MPLS和GMPLS网络的其他安全注意事项。
However, where the separate layers of an MLN/MRN network are operated as different administrative domains, additional security considerations may be given to the mechanisms for allowing LSP setup crossing one or more layer boundaries, for triggering lower-layer LSPs, or for VNT management. Similarly, consideration may be given to the amount of information shared between administrative domains, and the trade-off between multi-layer TE and confidentiality of information belonging to each administrative domain.
然而，在MLN/MRN网络的各个层作为不同的管理域操作的情况下，可以对用于允许LSP设置跨越一个或多个层边界、用于触发较低层LSP或用于VNT管理的机制给予额外的安全考虑。类似地，可以考虑在管理域之间共享的信息量，以及多层TE和属于每个管理域的信息的机密性之间的权衡。
It is expected that solution documents will include a full analysis of the security issues that any protocol extensions introduce.
预计解决方案文档将包括对任何协议扩展引入的安全问题的全面分析。
The authors would like to thank Adrian Farrel and the participants of ITU-T Study Group 15, Question 14 for their careful review. The authors would like to thank the IESG review team for rigorous review: special thanks to Tim Polk, Miguel Garcia, Jari Arkko, Dan Romascanu, and Dave Ward.
作者要感谢Adrian Farrel和ITU-T研究组15问题14的参与者的仔细审查。作者要感谢IESG审查小组的严格审查：特别感谢Tim Polk、Miguel Garcia、Jari Arkko、Dan Romascanu和Dave Ward。
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2119]Bradner，S.，“RFC中用于表示需求水平的关键词”，BCP 14，RFC 2119，1997年3月。
[RFC3945] Mannie, E., Ed., "Generalized Multi-Protocol Label Switching (GMPLS) Architecture", RFC 3945, October 2004.
[RFC3945]Mannie，E.，Ed.“通用多协议标签交换（GMPLS）体系结构”，RFC 39452004年10月。
[RFC4202] Kompella, K., Ed., and Y. Rekhter, Ed., "Routing Extensions in Support of Generalized Multi-Protocol Label Switching (GMPLS)", RFC 4202, October 2005.
[RFC4202]Kompella，K.，Ed.，和Y.Rekhter，Ed.，“支持通用多协议标签交换（GMPLS）的路由扩展”，RFC 4202，2005年10月。
[RFC4206] Kompella, K. and Y. Rekhter, "Label Switched Paths (LSP) Hierarchy with Generalized Multi-Protocol Label Switching (GMPLS) Traffic Engineering (TE)", RFC 4206, October 2005.
[RFC4206]Kompella，K.和Y.Rekhter，“具有通用多协议标签交换（GMPLS）流量工程（TE）的标签交换路径（LSP）层次结构”，RFC 4206，2005年10月。
[RFC4397] Bryskin, I. and A. Farrel, "A Lexicography for the Interpretation of Generalized Multiprotocol Label Switching (GMPLS) Terminology within the Context of the ITU-T's Automatically Switched Optical Network (ASON) Architecture", RFC 4397, February 2006.
[RFC4397]Bryskin，I.和A.Farrel，“在ITU-T自动交换光网络（ASON）体系结构背景下解释通用多协议标签交换（GMPLS）术语的词典编纂”，RFC 4397，2006年2月。
[RFC4726] Farrel, A., Vasseur, J.-P., and A. Ayyangar, "A Framework for Inter-Domain Multiprotocol Label Switching Traffic Engineering", RFC 4726, November 2006.
[RFC4726]Farrel，A.，Vasseur，J.-P.，和A.Ayyangar，“域间多协议标签交换流量工程框架”，RFC 4726，2006年11月。
[DYN-HIER] Shiomoto, K., Rabbat, R., Ayyangar, A., Farrel, A. and Z. Ali, "Procedures for Dynamically Signaled Hierarchical Label Switched Paths", Work in Progress, February 2008.
[DYN-HIER]Shiomoto，K.，Rabbat，R.，Ayyangar，A.，Farrel，A.和Z.Ali，“动态信号分层标签交换路径的程序”，正在进行的工作，2008年2月。
[MRN-EVAL] Le Roux, J.L., Ed., and D. Papadimitriou, Ed., "Evaluation of existing GMPLS Protocols against Multi Layer and Multi Region Networks (MLN/MRN)", Work in Progress, December 2007.
[MRN-EVAL]Le Roux，J.L.，Ed.，和D.Papadimitriou，Ed.，“针对多层和多区域网络（MLN/MRN）评估现有GMPLS协议”，正在进行的工作，2007年12月。
[RFC5146] Kumaki, K., Ed., "Interworking Requirements to Support Operation of MPLS-TE over GMPLS Networks", RFC 5146, March 2008.
[RFC5146]Kumaki，K.，Ed.“支持MPLS-TE在GMPLS网络上运行的互通要求”，RFC 5146，2008年3月。
[MPLS-SEC] Fang, L., Ed., "Security Framework for MPLS and GMPLS Networks", Work in Progress, February 2008.
[MPLS-SEC]Fang，L.，Ed.，“MPLS和GMPLS网络的安全框架”，正在进行的工作，2008年2月。
[RFC4802] Nadeau, T., Ed., and A. Farrel, Ed., "Generalized Multiprotocol Label Switching (GMPLS) Traffic Engineering Management Information Base", RFC 4802, February 2007.
[RFC4802]Nadeau，T.，Ed.，和A.Farrel，Ed.，“通用多协议标签交换（GMPLS）流量工程管理信息库”，RFC 4802，2007年2月。
[RFC4803] Nadeau, T., Ed., and A. Farrel, Ed., "Generalized Multiprotocol Label Switching (GMPLS) Label Switching Router (LSR) Management Information Base", RFC 4803, February 2007.
[RFC4803]Nadeau，T.，Ed.，和A.Farrel，Ed.，“通用多协议标签交换（GMPLS）标签交换路由器（LSR）管理信息库”，RFC 4803，2007年2月。
[RFC4847] Takeda, T., Ed., "Framework and Requirements for Layer 1 Virtual Private Networks", RFC 4847, April 2007.
[RFC4847]武田，T.，编辑，“第1层虚拟专用网络的框架和要求”，RFC 4847，2007年4月。
[RFC4972] Vasseur, JP., Ed., Leroux, JL., Ed., Yasukawa, S., Previdi, S., Psenak, P., and P. Mabbey, "Routing Extensions for Discovery of Multiprotocol (MPLS) Label Switch Router (LSR) Traffic Engineering (TE) Mesh Membership", RFC 4972, July 2007.
[RFC4972]Vasseur，JP.，Ed.，Leroux，JL.，Ed.，Yasukawa，S.，Previdi，S.，Psenak，P.，和P.Mabbey，“发现多协议（MPLS）标签交换路由器（LSR）流量工程（TE）网状成员资格的路由扩展”，RFC 4972，2007年7月。
[GMPLS-OAM] Nadeau, T., Otani, T. Brungard, D., and A. Farrel, "OAM Requirements for Generalized Multi-Protocol Label Switching (GMPLS) Networks", Work in Progress, October 2007.
[GMPLS-OAM]Nadeau，T.，Otani，T.Brungard，D.，和A.Farrel，“通用多协议标签交换（GMPLS）网络的OAM要求”，正在进行的工作，2007年10月。
Eiji Oki NTT Network Service Systems Laboratories 3-9-11 Midori-cho, Musashino-shi Tokyo 180-8585 Japan Phone: +81 422 59 3441 EMail: oki.eiji@lab.ntt.co.jp
Eiji Oki NTT网络服务系统实验室3-9-11 Midori cho，武藏县东京180-8585日本电话：+81 422 59 3441电子邮件：Oki。eiji@lab.ntt.co.jp
Ichiro Inoue NTT Network Service Systems Laboratories 3-9-11 Midori-cho, Musashino-shi Tokyo 180-8585 Japan Phone: +81 422 59 3441 EMail: ichiro.inoue@lab.ntt.co.jp
井上一郎NTT网络服务系统实验室3-9-11武藏县Midori cho，东京180-8585日本电话：+81 422 59 3441电子邮件：Ichiro。inoue@lab.ntt.co.jp
Emmanuel Dotaro Alcatel-Lucent Route de Villejust 91620 Nozay France Phone: +33 1 3077 2670 EMail: emmanuel.dotaro@alcatel-lucent.fr
Emmanuel Dotaro Alcatel-Lucent Route de Villejust 91620 Nozay France电话：+33 1 3077 2670电子邮件：Emmanuel。dotaro@alcatel-朗讯
Authors' Addresses
作者地址
Kohei Shiomoto NTT Network Service Systems Laboratories 3-9-11 Midori-cho, Musashino-shi Tokyo 180-8585 Japan EMail: shiomoto.kohei@lab.ntt.co.jp
Kohei Shiomoto NTT网络服务系统实验室3-9-11 Midori cho，武藏市东京180-8585日本电子邮件：Shiomoto。kohei@lab.ntt.co.jp
Dimitri Papadimitriou Alcatel-Lucent Copernicuslaan 50 B-2018 Antwerpen Belgium Phone : +32 3 240 8491 EMail: dimitri.papadimitriou@alcatel-lucent.be
Dimitri Papadimitriou Alcatel-Lucent Copernicuslaan 50 B-2018比利时安特卫普电话：+32 3 240 8491电子邮件：Dimitri。papadimitriou@alcatel-朗讯
Jean-Louis Le Roux France Telecom R&D Av Pierre Marzin 22300 Lannion France EMail: jeanlouis.leroux@orange-ftgroup.com
Jean-Louis Le Roux法国电信研发Av Pierre Marzin 22300 Lannion France电子邮件：jeanlouis。leroux@orange-ftgroup.com
Martin Vigoureux Alcatel-Lucent Route de Villejust 91620 Nozay France Phone: +33 1 3077 2669 EMail: martin.vigoureux@alcatel-lucent.fr
Martin Vigoureux Alcatel-Lucent Route de Villejust 91620 Nozay France电话：+33 1 3077 2669电子邮件：Martin。vigoureux@alcatel-朗讯
Deborah Brungard AT&T Rm. D1-3C22 - 200 S. Laurel Ave. Middletown, NJ 07748 USA Phone: +1 732 420 1573 EMail: dbrungard@att.com
德博拉·布伦加德AT&T室。D1-3C22-200美国新泽西州米德尔敦S.Laurel Ave.07748电话：+1 732 420 1573电子邮件：dbrungard@att.com
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