Internet Engineering Task Force (IETF) D. Black, Ed.
Request for Comments: 6307 EMC Corporation
Category: Standards Track L. Dunbar, Ed.
ISSN: 2070-1721 Huawei Technologies
M. Roth
Infinera
R. Solomon
Orckit-Corrigent
April 2012
Internet Engineering Task Force (IETF) D. Black, Ed.
Request for Comments: 6307 EMC Corporation
Category: Standards Track L. Dunbar, Ed.
ISSN: 2070-1721 Huawei Technologies
M. Roth
Infinera
R. Solomon
Orckit-Corrigent
April 2012
Encapsulation Methods for Transport of Fibre Channel Traffic over MPLS Networks
MPLS网络上光纤通道流量传输的封装方法
Abstract
摘要
A Fibre Channel pseudowire (PW) is used to carry Fibre Channel traffic over an MPLS network. This enables service providers to take advantage of MPLS to offer "emulated" Fibre Channel services. This document specifies the encapsulation of Fibre Channel traffic within a pseudowire. It also specifies the common procedures for using a PW to provide a Fibre Channel service.
光纤通道伪线（PW）用于通过MPLS网络承载光纤通道流量。这使服务提供商能够利用MPLS提供“模拟”光纤通道服务。本文档指定了光纤通道通信量在伪线中的封装。它还指定了使用PW提供光纤通道服务的常见过程。
Status of This Memo
关于下段备忘
This is an Internet Standards Track document.
这是一份互联网标准跟踪文件。
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). Further information on Internet Standards is available in 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。有关互联网标准的更多信息，请参见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/rfc6307.
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/rfc6307.
Copyright Notice
版权公告
Copyright (c) 2012 IETF Trust and the persons identified as the document authors. All rights reserved.
版权所有（c）2012 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 ....................................................3
1.1. Transparency ...............................................3
1.2. Bandwidth Efficiency .......................................4
1.3. Reliability ................................................5
1.4. Conventions Used in This Document ..........................5
2. Reference Model .................................................6
3. Encapsulation ...................................................8
3.1. The Control Word ..........................................10
3.2. MTU Requirements ..........................................11
3.3. Mapping of FC Traffic to PW Packets........................11
3.3.1. FC Data Frames (PT=0) and FC Login Frames (PT=1) ...11
3.3.2. FC Primitive Sequences and Primitive
Signals (PT=2) .....................................12
3.3.3. FC PW Control Frames (PT=6) ........................14
3.4. PW Failure Mapping ........................................15
4. Signaling of FC Pseudowires ....................................15
5. Timing Considerations ..........................................15
6. Security Considerations ........................................17
7. Applicability Statement ........................................17
8. IANA Considerations ............................................18
9. Acknowledgments ................................................19
10. Normative References ..........................................19
11. Informative References ........................................20
1. Introduction ....................................................3
1.1. Transparency ...............................................3
1.2. Bandwidth Efficiency .......................................4
1.3. Reliability ................................................5
1.4. Conventions Used in This Document ..........................5
2. Reference Model .................................................6
3. Encapsulation ...................................................8
3.1. The Control Word ..........................................10
3.2. MTU Requirements ..........................................11
3.3. Mapping of FC Traffic to PW Packets........................11
3.3.1. FC Data Frames (PT=0) and FC Login Frames (PT=1) ...11
3.3.2. FC Primitive Sequences and Primitive
Signals (PT=2) .....................................12
3.3.3. FC PW Control Frames (PT=6) ........................14
3.4. PW Failure Mapping ........................................15
4. Signaling of FC Pseudowires ....................................15
5. Timing Considerations ..........................................15
6. Security Considerations ........................................17
7. Applicability Statement ........................................17
8. IANA Considerations ............................................18
9. Acknowledgments ................................................19
10. Normative References ..........................................19
11. Informative References ........................................20
Fibre Channel (FC) is a high-speed communications technology, used primarily for Storage Area Networks (SANs). Within a single site (e.g., data center), an FC-based SAN connects servers to storage systems, and FC can be extended across sites. When FC is extended across multiple sites, the most common usage is storage replication in support of recovery from disasters (e.g., flood or fire that takes a site out of operation). This is particularly the case over longer distances where network latency results in unacceptable performance for a server whose storage is not at the same site. Fibre Channel is standardized by the INternational Committee for Information Technology Standards (INCITS) Technical Committee T11 [T11], and multiple methods for encapsulating and transporting FC traffic over other networks have been developed [FC-BB-6].
光纤通道（FC）是一种高速通信技术，主要用于存储区域网络（SAN）。在单个站点（如数据中心）内，基于FC的SAN将服务器连接到存储系统，并且FC可以跨站点扩展。当FC扩展到多个站点时，最常见的用途是存储复制，以支持灾难恢复（例如，导致站点停止运行的洪水或火灾）。对于存储不在同一站点的服务器来说，网络延迟会导致无法接受的性能，在较长距离上尤其如此。光纤通道由国际信息技术标准委员会（INCITS）技术委员会T11[T11]标准化，并开发了多种封装和在其他网络上传输FC流量的方法[FC-BB-6]。
Fibre Channel Over TCP/IP (FCIP), as described in [RFC3821] and [FC-BB-6], interconnects otherwise isolated FC SANs over IP Networks. FCIP uses FC Frame Encapsulation [RFC3643] to encapsulate FC frames for tunneling over an IP-based network. Since IP networks may drop or reorder packets, FCIP relies on TCP to retransmit dropped frames and restore the delivery order of reordered frames. Due to possible delay variation and TCP timeouts, special timing mechanisms are required to ensure correct Fibre Channel operation over FCIP [FC-BB-6].
如[RFC3821]和[FC-BB-6]中所述，TCP/IP光纤通道（FCIP）通过IP网络互连其他隔离的FC SAN。FCIP使用FC帧封装[RFC3643]来封装FC帧，以便在基于IP的网络上进行隧道传输。由于IP网络可能丢弃或重新排序数据包，FCIP依赖TCP重新传输丢弃的帧并恢复重新排序的帧的传递顺序。由于可能的延迟变化和TCP超时，需要特殊的定时机制来确保光纤通道在FCIP上的正确运行[FC-BB-6]。
MPLS networks can be provisioned and operated with very low loss rates and very low probability of reordering, making it possible to directly interconnect Fibre Channel ports over MPLS. A Fibre Channel pseudowire (FC PW) is a method to transparently transport FC traffic over an MPLS network resulting in behavior similar to a pair of FC ports that are directly connected by a physical FC link. The result is simpler control processing in comparison to FCIP.
MPLS网络可以以极低的丢失率和极低的重新排序概率配置和运行，从而可以通过MPLS直接互连光纤通道端口。光纤通道伪线（FC PW）是一种通过MPLS网络透明传输FC流量的方法，其行为类似于通过物理FC链路直接连接的一对FC端口。与FCIP相比，其结果是更简单的控制处理。
This document specifies the encapsulation of FC traffic into an MPLS pseudowire and related PW procedures to transport FC traffic over MPLS PWs. The complete FC pseudowire specification consists of this document and the FC PW portion of the T11 [FC-BB-5/AM1] standard. The following subsections describe some of the requirements for transporting FC traffic over an MPLS network.
本文档规定了将FC流量封装到MPLS伪线中，以及通过MPLS PWs传输FC流量的相关PW过程。完整的FC伪线规范包括本文件和T11[FC-BB-5/AM1]标准的FC PW部分。以下小节描述了通过MPLS网络传输FC流量的一些要求。
Transparent extension of an FC link is a key requirement for transporting FC traffic over a PW. This requires the FC PW to emulate an FC link between two FC ports, similar to the approach defined for FC over GFPT in [FC-BB-6]. GFPT is an Asynchronous Transparent Generic Framing Procedure specified by ITU-T; see
FC链路的透明扩展是通过PW传输FC流量的关键要求。这要求FC PW模拟两个FC端口之间的FC链路，类似于[FC-BB-6]中为FC over GFPT定义的方法。GFPT是ITU-T规定的异步透明通用成帧过程；看见
[FC-BB-6] for details and reference to the ITU-T specifications. This results in transparent forwarding of FC traffic over the MPLS network from both the FC fabric and the network operator points of view.
[FC-BB-6]了解ITU-T规范的详细信息和参考。这导致从FC结构和网络运营商的角度通过MPLS网络透明地转发FC流量。
Transparency distinguishes the FC PW approach from FCIP. An FC PW logically connects the FC port on the FC link attached to one end of the PW directly with the FC port on the far end of the FC link attached to the other end of the PW, whereas FCIP introduces FC B_Ports at both ends of the extended FC link; each FC B_Port is connected to an FC E_Port in an FC switch on the same side of the link extension.
透明度将FC PW方法与FCIP区分开来。FC PW将连接至PW一端的FC链路上的FC端口与连接至PW另一端的FC链路远端上的FC端口直接逻辑连接，而FCIP在扩展FC链路的两端引入FC B_端口；每个FC B_端口都连接到链路扩展同一侧的FC交换机中的FC E_端口。
The bandwidth allocated to a PW may be less than the rate of the attached FC port. When there is no data exchange on a native FC link, Idle Primitive Signals are continuously exchanged between the two FC ports. In order to improve the bandwidth efficiency across the MPLS network, it is necessary for the FC PW Provider Edge (PE) to suppress (or drop) the Idle Primitive Signals generated by its adjacent FC ports. The far-end FC PW PE regenerates Idle Primitive Signals to send to its adjacent FC port as required; see [FC-BB-5/AM1].
分配给PW的带宽可能小于连接的FC端口的速率。当本机FC链路上没有数据交换时，两个FC端口之间会连续交换空闲原始信号。为了提高整个MPLS网络的带宽效率，FC PW提供商边缘（PE）有必要抑制（或丢弃）其相邻FC端口生成的空闲原始信号。远端FC PW PE根据需要重新生成空闲原始信号以发送到其相邻的FC端口；见[FC-BB-5/AM1]。
FC link control protocols require an FC port to continuously send the same FC Primitive Sequence [FC-FS-2] until a reply is received or some other event occurs. To improve bandwidth efficiency, the FC PW PE encapsulates a subset of repeated FC Primitive Sequences to send across the WAN [FC-BB-5/AM1]. For example, in a sequence of identical received primitives, only every fourth primitive may be sent across the MPLS network. Alternatively, a time-based approach may be used to send a copy of the repeated FC Primitive Sequence once every few milliseconds. The far-end FC PW PE regenerates the FC link behavior by continuously sending the Primitive Sequence most recently received from the WAN until a new primitive signal, primitive sequence, or data frame is received from the WAN.
FC链路控制协议要求FC端口连续发送相同的FC基本序列[FC-FS-2]，直到收到应答或发生其他事件。为了提高带宽效率，FC PW PE封装了重复FC原语序列的子集，以通过WAN发送[FC-BB-5/AM1]。例如，在相同的接收原语序列中，只有每四个原语可以通过MPLS网络发送。或者，可以使用基于时间的方法每隔几毫秒发送一次重复FC原语序列的副本。远端FC PW PE通过连续发送最近从广域网接收到的基本序列，直到从广域网接收到新的基本信号、基本序列或数据帧，来重新生成FC链路行为。
The sending FC PW PE may unilaterally choose any convenient subset for sending the same FC Primitive Sequence. This is acceptable because the receiving FC PW PE generates a continuous stream of the most recently received FC Primitive Sequence on the outgoing native FC link, independent of the arrival rate of that FC Primitive Sequence from the WAN. In practice, a 10:1 reduction in FC Primitive Sequence transmission rate achieves 90% of the bandwidth benefits without loss of FC functionality, and sending a copy every few milliseconds does not pose a serious risk of exceeding the timeouts specified in Section 5 below.
发送FC PW PE可以单方面选择用于发送相同FC原语序列的任何方便子集。这是可接受的，因为接收FC PW PE在传出本机FC链路上生成最近接收到的FC基本序列的连续流，与来自WAN的该FC基本序列的到达率无关。实际上，FC原始序列传输速率的10:1降低可实现90%的带宽收益，而不会丢失FC功能，并且每隔几毫秒发送一次副本不会造成超过下面第5节规定的超时的严重风险。
These bandwidth-efficiency techniques may cause changes in the FC traffic that traverses an FC PW (e.g., number of Idle Primitive Signals or number of identical Primitive Sequences), but the far-end FC PW PE's regeneration of FC link behavior on the attached FC port is transparent to the FC ports connected to each PW PE.
这些带宽效率技术可能导致穿过FC PW的FC通信量发生变化（例如，空闲基本信号的数量或相同基本序列的数量），但远端FC PW PE在连接的FC端口上对FC链路行为的再生对连接到每个PW PE的FC端口是透明的。
Fibre Channel does not employ a native frame retransmission protocol and treats most frame delivery failures as errors. FC SAN traffic requires a very low frame loss rate because the typical result of a failure to deliver a frame is an I/O operation failure. Recovery from such I/O failures involves I/O operation retries after what may be a significant delay (30-second and 60-second timeouts are common). In addition, such retries are likely to be logged as errors indicating possible problems with FC equipment or cables. Hence, drops, errors, and discards of FC frames must be very rare for an FC PW.
光纤通道不采用本机帧重传协议，并将大多数帧传递失败视为错误。FC SAN通信需要非常低的帧丢失率，因为无法传送帧的典型结果是I/O操作失败。从此类I/O故障中恢复包括在可能出现明显延迟（通常为30秒和60秒超时）后重试I/O操作。此外，此类重试可能被记录为错误，表明FC设备或电缆可能存在问题。因此，对于FC PW，FC帧的丢弃、错误和丢弃必须非常罕见。
FC SAN implementations have limited tolerance for frame reordering. Any reordering affecting more than a few frames within a single higher-level operation (e.g., a read or write I/O) is usually treated as an error by the destination FC port, resulting in discards of the frames involved; some deployed FC implementations treat all such within-operation frame reordering as errors that result in frame discards. As a result, FC frame reordering must be minimized for an FC PW.
FC SAN实现对帧重新排序的容忍度有限。在单个高级操作（例如，读或写I/O）中影响多个帧的任何重新排序通常被目标FC端口视为错误，从而导致丢弃所涉及的帧；一些部署的FC实现将所有此类操作帧内重新排序视为导致帧丢弃的错误。因此，FC PW的FC帧重新排序必须最小化。
The FC PW does not compensate for frame drops, discards, or reordering. The MPLS network that hosts the FC PW is expected to be designed and operated in a fashion that makes such events very rare.
FC PW不补偿帧丢失、丢弃或重新排序。承载FC PW的MPLS网络的设计和运行方式将使此类事件非常罕见。
In contrast to the Time to Live (TTL) field in an IP packet, FC uses a constant delivery timeout value (R_A_TOV) for which 10 seconds is the default. Each FC frame must be delivered or discarded within that timeout period after it is sent; see Section 5.
与IP数据包中的生存时间（TTL）字段不同，FC使用恒定的传递超时值（R_a_TOV），默认值为10秒。每个FC帧必须在发送后的超时时间内交付或丢弃；见第5节。
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119].
本文件中的关键词“必须”、“不得”、“必需”、“应”、“不应”、“应”、“不应”、“建议”、“可”和“可选”应按照[RFC2119]中所述进行解释。
An FC PW extends a native FC link over an MPLS network. This document specifies the PW encapsulation for FC. Figure 1 describes the reference models (derived from [RFC3985]) that support the FC PW. FC traffic is received by PE1's FC attachment channel, encapsulated at PE1, transported across MPLS network, decapsulated at PE2, and transmitted onward via the PE2's FC attachment channel. This document assumes that a pseudowire can be provisioned statically or via a signaling protocol as defined in [RFC4447].
FC PW通过MPLS网络扩展本机FC链路。本文件规定了FC的PW封装。图1描述了支持FC PW的参考模型（源自[RFC3985]）。FC通信量由PE1的FC连接信道接收，封装在PE1处，通过MPLS网络传输，在PE2处解封装，并通过PE2的FC连接信道向前传输。本文档假设可以静态地或通过[RFC4447]中定义的信令协议提供伪线。
|<-------------- Emulated Service ----------------->|
| |
| |<------- Pseudowire -------->| |
| | | |
| | |<-- MPLS Tunnel -->| | |
| V V V V |
V AC +----+ +----+ AC V
+-----+ | | PE1|===================| PE2| | +-----+
| |----------|............PW1..............|----------| |
| CE1 | | | | | | | | CE2 |
| |----------|............PW2..............|----------| |
+-----+ ^ | | |===================| | | ^ +-----+
^ | +----+ +----+ | | ^
| | Provider Edge 1 Provider Edge 2 | |
| | | |
Customer | | Customer
Edge 1 | | Edge 2
| |
| |
Native FC service Native FC service
|<-------------- Emulated Service ----------------->|
| |
| |<------- Pseudowire -------->| |
| | | |
| | |<-- MPLS Tunnel -->| | |
| V V V V |
V AC +----+ +----+ AC V
+-----+ | | PE1|===================| PE2| | +-----+
| |----------|............PW1..............|----------| |
| CE1 | | | | | | | | CE2 |
| |----------|............PW2..............|----------| |
+-----+ ^ | | |===================| | | ^ +-----+
^ | +----+ +----+ | | ^
| | Provider Edge 1 Provider Edge 2 | |
| | | |
Customer | | Customer
Edge 1 | | Edge 2
| |
| |
Native FC service Native FC service
Figure 1 - PWE3 FC Interface Reference Configuration
图1-PWE3 FC接口参考配置
The following reference model describes the termination point of each end of the PW within the PE:
以下参考模型描述了PE内PW各端的终止点：
+-----------------------------------+
| PE |
+---+ +-+ +-----+ +------+ +------+ +-+
| | |P| | | |PW ter| | MPLS | |P|
| |<==|h|<=| NSP |<=|minati|<=|Tunnel|<=|h|<== From network
| | |y| | | |on | | | |y|
| C | +-+ +-----+ +------+ +------+ +-+
| E | | |
| | +-+ +-----+ +------+ +------+ +-+
| | |P| | | |PW ter| | MPLS | |P|
| |==>|h|=>| NSP |=>|minati|=>|Tunnel|=>|h|==> To network
| | |y| | | |on | | | |y|
+---+ +-+ +-----+ +------+ +------+ +-+
| |
+-----------------------------------+
+-----------------------------------+
| PE |
+---+ +-+ +-----+ +------+ +------+ +-+
| | |P| | | |PW ter| | MPLS | |P|
| |<==|h|<=| NSP |<=|minati|<=|Tunnel|<=|h|<== From network
| | |y| | | |on | | | |y|
| C | +-+ +-----+ +------+ +------+ +-+
| E | | |
| | +-+ +-----+ +------+ +------+ +-+
| | |P| | | |PW ter| | MPLS | |P|
| |==>|h|=>| NSP |=>|minati|=>|Tunnel|=>|h|==> To network
| | |y| | | |on | | | |y|
+---+ +-+ +-----+ +------+ +------+ +-+
| |
+-----------------------------------+
Figure 2 - PW Reference Diagram
图2-PW参考图
The Native Service Processing (NSP) function includes the following functionality:
本机服务处理（NSP）功能包括以下功能：
o Idle Suppression: any FC Idle Primitive Signals received from the source PE's attached FC port are suppressed and regenerated at the destination PE to send on its attached FC port when there is no other FC traffic to send;
o 空闲抑制：当没有其他FC通信要发送时，从源PE连接的FC端口接收的任何FC空闲原始信号在目标PE被抑制并重新生成，以在其连接的FC端口上发送；
o FC Primitive Sequence Reduction: a subset of repetitive FC Primitive Sequences received from the attached FC port at the source PE is selected for WAN transmission, with the destination PE sending the FC Primitive Sequence most recently received from the WAN on the destination PE's attached FC port continuously until a new packet is received from the WAN; and
o FC基元序列缩减：选择从源PE处连接的FC端口接收的重复FC基元序列子集进行WAN传输，目的地PE在目的地PE的连接FC端口上连续发送最近从WAN接收到的FC原语序列，直到从WAN接收到新分组；和
o Flow Control: the Alternate Simple Flow Control (ASFC) protocol is used for buffer management in concert with the peer PW PE's NSP function so that FC traffic is not dropped. ASFC is a simple pause/resume protocol that allows operation repetition; the receiver responds to the first pause or resume operation in an identical sequence of operations and ignores the rest of the sequence.
o 流量控制：备用简单流量控制（ASFC）协议与对等PW PE的NSP功能一起用于缓冲区管理，以便不会丢弃FC流量。ASFC是一个简单的暂停/恢复协议，允许操作重复；接收器以相同的操作序列响应第一次暂停或恢复操作，并忽略该序列的其余部分。
The NSP flow control functionality is required to extend FC's credit-based flow control to address situations where the number of buffer credits available to an FC link is insufficient to utilize the available bandwidth over the additional distance and latency
NSP流量控制功能需要扩展FC基于信用的流量控制，以解决FC链路可用的缓冲区信用数不足以利用额外距离和延迟上的可用带宽的情况
represented by the FC pseudowire. The NSPs avoid this problem by inserting ASFC into FC's link flow control used on the attached FC ports; see [FC-BB-5/AM1].
由FC伪线表示。NSPs通过将ASFC插入连接的FC端口上使用的FC链路流控制来避免此问题；见[FC-BB-5/AM1]。
In contrast, Idle Suppression and FC Primitive Sequence Reduction are bandwidth optimizations that are included in the NSP for clarity in this document. Analogous optimizations are not treated as part of the NSP by other pseudowires (e.g., Asynchronous Transfer Mode (ATM) idle frame suppression is not considered to be an NSP function by [RFC4717]).
相比之下，空闲抑制和FC基元序列减少是带宽优化，为了本文档的清晰性，NSP中包括了这些优化。类似优化不被其他伪线视为NSP的一部分（例如，[RFC4717]不将异步传输模式（ATM）空闲帧抑制视为NSP功能）。
The NSP function is specified in detail by [FC-BB-5/AM1].
NSP功能由[FC-BB-5/AM1]详细规定。
This specification provides port-to-port transport of FC-encapsulated traffic. There are a number of port types defined by Fibre Channel, including:
本规范提供FC封装流量的端口到端口传输。光纤通道定义了多种端口类型，包括：
o N_port: a port on the node (e.g., host or storage device) used with both FC-P2P (Point to Point) or FC-SW (switched fabric) topologies. Also known as a Node port.
o N_端口：节点（例如主机或存储设备）上的端口，用于FC-P2P（点对点）或FC-SW（交换结构）拓扑。也称为节点端口。
o NL_port: a port on the node used with an FC-AL (Arbitrated Loop) topology. Also known as a Node Loop port.
o NL_端口：节点上与FC-AL（仲裁环路）拓扑一起使用的端口。也称为节点循环端口。
o F_port: a port on the switch that connects to a node point- to-point (i.e., connects to an N_port). Also known as a Fabric port. An F_port is not loop capable.
o F_端口：交换机上连接到节点点对点（即连接到N_端口）的端口。也称为结构端口。F_端口不支持环路。
o FL_port: a port on the switch that connects to an FC-AL loop (i.e., to NL_ports). Also known as a Fabric Loop port.
o FL_端口：交换机上连接到FC-AL环路（即NL_端口）的端口。也称为结构循环端口。
o E_port: a port used to connect two Fibre Channel switches. Also known as an Expansion port. When E_ports between two switches are connected to form a link, that link is referred to as an inter-switch link (ISL).
o E_端口：用于连接两个光纤通道交换机的端口。也称为扩展端口。当两个交换机之间的E_端口连接以形成链路时，该链路称为交换机间链路（ISL）。
Among the port types listed above, only the following FC connections (as specified in [FC-BB-5/AM1]) are supported by an FC PW over MPLS:
在上面列出的端口类型中，MPLS上的FC PW仅支持以下FC连接（如[FC-BB-5/AM1]中所述）：
o N_Port to N_Port, established by an FC PLOGI (Port Login) operation
o N_端口到N_端口，由FC PLOGI（端口登录）操作建立
o N_Port to F_Port, established by an FC FLOGI (Fabric Login) operation
o N_端口到F_端口，由FC FLOGI（结构登录）操作建立
o E_Port to E_Port, established by an FC ELP (Exchange Link Parameters) operation
o E_端口到E_端口，由FC ELP（交换链路参数）操作建立
FC traffic flowing over an FC PW is subdivided into four payload types (PTs) that are encoded in the PW Control Word (see Section 3.1):
流经FC PW的FC流量细分为四种有效负载类型（PT），在PW控制字中进行编码（见第3.1节）：
1. FC login traffic (PT = 1): FC login operations and responses that establish connections between FC ports. The three FC login operations are PLOGI, FLOGI, and ELP. These operations and their responses may require the NSP to allocate buffer resources. See the specification of Login Exchange Monitors in [FC-BB-5/AM1].
1. FC登录流量（PT=1）：在FC端口之间建立连接的FC登录操作和响应。三个FC登录操作是PLOGI、FLOGI和ELP。这些操作及其响应可能需要NSP分配缓冲区资源。请参阅[FC-BB-5/AM1]中的登录交换监视器规范。
2. FC data traffic (PT = 0): All FC frames other than those involved in an FC login operation.
2. FC数据流量（PT=0）：除涉及FC登录操作的帧外的所有FC帧。
3. FC Primitive Sequences and Signals (PT = 2): Native FC link control operations; 4-character primitive sequences and signals that are not encapsulated in FC frames. See [FC-BB-5/AM1] and [FC-FS-2].
3. FC基本序列和信号（PT=2）：本机FC链路控制操作；未封装在FC帧中的4字符基元序列和信号。见[FC-BB-5/AM1]和[FC-FS-2]。
4. FC PW Control (PT = 6): FC PW control operations exchanged only between the endpoints of the PW. FC PW control operations are used for ASFC flow control, ping (e.g., for round-trip latency measurement), and reporting native FC link errors. See [FC-BB-5/AM1].
4. FC PW控制（PT=6）：仅在PW端点之间交换的FC PW控制操作。FC PW控制操作用于ASFC流量控制、ping（例如，用于往返延迟测量）和报告本机FC链路错误。见[FC-BB-5/AM1]。
This FC PW specification is limited to use with FC service classes 2, 3, and F; see [FC-FS-2]. Other FC service classes (e.g., 1, 4, and 6) MUST NOT be used with an FC PW. Numbered FC service classes are used for end-to-end FC traffic, whereas service class F is used for inter-switch traffic in an FC switched fabric.
本FC PW规范仅限于与FC服务等级2、3和F一起使用；见[FC-FS-2]。其他FC服务类别（如1、4和6）不得与FC PW一起使用。编号的FC服务类别用于端到端FC流量，而服务类别F用于FC交换结构中的交换机间流量。
This FC PW specification is limited to native FC attachment links that employ an 8b/10b transmission code (see [FC-FS-2]). The protocol specified in this document converts a received 10b code to its 8b counterpart for PW encapsulation and hence does not support attached FC links that use a 64b/66b transmission code (e.g., 10GFC and 16GFC); such links MUST NOT be attached to an FC PW PE unless their link speed can be negotiated to one that uses 8b/10b encoding. If an invalid 10b code that cannot be converted to an 8b code is received from an FC link, the PE sends an FC PW control frame to report the error (see [FC-BB-5/AM1]).
本FC PW规范仅限于采用8b/10b传输代码的本机FC连接链路（见[FC-FS-2]）。本文件中规定的协议将接收到的10b代码转换为8b对应的PW封装，因此不支持使用64b/66b传输代码（例如10GFC和16GFC）的连接FC链路；此类链路不得连接到FC PW PE，除非其链路速度可以协商为使用8b/10b编码的链路速度。如果从FC链路接收到无法转换为8b代码的无效10b代码，则PE发送FC PW控制帧以报告错误（请参阅[FC-BB-5/AM1]）。
The Generic PW Control Word, as defined in "Pseudowire Emulation Edge-to-Edge (PWE3) Control Word for Use over an MPLS PSN" [RFC4385], MUST be used for FC PW to facilitate the transport of short packets (by setting the Length field as detailed below) and convey the flag bits defined below. The structure of the Control Word for the FC PW is as follows:
“用于MPLS PSN的伪线仿真边到边（PWE3）控制字”[RFC4385]中定义的通用PW控制字必须用于FC PW，以促进短数据包的传输（通过设置下面详述的长度字段）并传输下面定义的标志位。FC PW的控制字结构如下所示：
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0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0| PT |X|0 0| Length | Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0| PT |X|0 0| Length | Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3 - Control Word Structure
图3-控制字结构
The first four bits of the PW Control Word MUST be set to 0 by the ingress PE to indicate PW data.
PW控制字的前四位必须由入口PE设置为0，以指示PW数据。
Three of the four flag bits are used to convey the Payload Type (PT) indication. The 3-bit binary value in this field identifies the payload type carried by a PW packet. The following types are defined:
四个标志位中的三个用于传送有效负载类型（PT）指示。此字段中的3位二进制值标识PW数据包携带的有效负载类型。定义了以下类型：
PT = 0: FC data frame.
PT=0:FC数据帧。
PT = 1: FC login frame.
PT=1:FC登录帧。
PT = 2: FC Primitive Sequence(s) and/or Primitive Signal(s).
PT=2:FC基本序列和/或基本信号。
PT = 6: FC PW control frame (refer to [FC-BB-5/AM1] for usage).
PT=6:FC PW控制框架（参考[FC-BB-5/AM1]了解用法）。
Packets with other values in the PT field are not valid for the FC PW and MUST be discarded by the receiving FC PW PE.
PT字段中具有其他值的数据包对于FC PW无效，必须由接收FC PW PE丢弃。
The X flag bit is not used by this version of the protocol. It SHOULD be set to zero by the sender and MUST be ignored by the receiver.
此版本的协议不使用X标志位。发送方应将其设置为零，接收方必须忽略它。
The fragmentation bits (bits 8-9) are not used by the FC PW protocol. These bits may be used in the future for FC-specific indications as defined in [RFC4385]. The fragmentation bits SHOULD be set to zero by the ingress PE and MUST be ignored by the egress PE.
FC PW协议不使用分段位（位8-9）。这些位将来可用于[RFC4385]中定义的FC特定指示。碎片位应由入口PE设置为零，且必须由出口PE忽略。
The Length field enables recovery of the original pseudowire packet when a short packet is padded to the minimum 64-octet packet size required for Ethernet; see [RFC4385]. The Length field MUST be used for packets shorter than 64 octets, MUST be set to zero for longer packets, and MUST be processed according to the rules specified in [RFC4385].
当短数据包被填充到以太网所需的最小64个八位字节数据包大小时，长度字段允许恢复原始伪线数据包；参见[RFC4385]。长度字段必须用于长度小于64个八位字节的数据包，长度较长的数据包必须设置为零，并且必须根据[RFC4385]中指定的规则进行处理。
The sequence number is not used for the FC PW; it MUST be set to 0 by the ingress PE and MUST be ignored by the egress PE.
序列号不用于FC PW；入口PE必须将其设置为0，出口PE必须将其忽略。
The MPLS network MUST be able to transport the largest Fibre Channel frame after encapsulation, including the overhead associated with the encapsulation. The maximum FC frame size is 2164 octets without PW and MPLS labels (refer to Figure 4); this maximum size is a constant value that is required for all FC implementations [FC-FS-2]. The MPLS network SHOULD accommodate frames of up to 2500 octets in order to support possible future increases in the maximum FC frame size.
MPLS网络必须能够在封装后传输最大的光纤通道帧，包括与封装相关的开销。最大FC帧大小为2164个八位字节，无PW和MPLS标签（参见图4）；此最大大小是所有FC实现所需的常量值[FC-FS-2]。MPLS网络应容纳多达2500个八位字节的帧，以支持将来可能增加的最大FC帧大小。
Fragmentation, as described in [RFC4623], SHALL NOT be used for an FC PW; therefore, the network MUST be configured with a minimum MTU that is sufficient to transport the largest encapsulated FC frame.
[RFC4623]中所述的碎片不得用于FC PW；因此，网络必须配置足够传输最大封装FC帧的最小MTU。
FC frames, Primitive Sequences, and Primitive Signals are transported over the PW. All packet types are carried over a single PW. In addition to the PW Control Word, an FC Encapsulation Header is included in the PW packet. This FC Encapsulation Header is not used in this version of the protocol; it SHOULD be set to zero by the sender and MUST be ignored by the receiver.
FC帧、基本序列和基本信号通过PW传输。所有包类型都通过单个PW进行传输。除PW控制字外，PW数据包中还包括FC封装头。此FC封装头不用于此版本的协议；发送方应将其设置为零，接收方必须忽略它。
FC data frames and FC login frames share a common encapsulation format, except that the PT field in the FC PW Control Word is set to 0 for data frames and is set to 1 for login frames. An FC login frame contains an FC PLOGI, FLOGI, or ELP operation or response that requires special processing by the NSP in support of flow control; see [FC-BB-5/AM1].
FC数据帧和FC登录帧共享一种通用的封装格式，但FC PW控制字中的PT字段对于数据帧设置为0，对于登录帧设置为1。FC登录框架包含FC PLOGI、FLOGI或ELP操作或响应，需要NSP进行特殊处理以支持流量控制；见[FC-BB-5/AM1]。
Each FC data frame or login frame is mapped to a PW packet, including the Start Of Frame (SOF) delimiter, frame header, Cyclic Redundancy Check (CRC) field, and the End Of Frame (EOF) delimiter, as shown in Figure 4.
每个FC数据帧或登录帧都映射到PW数据包，包括帧开始（SOF）分隔符、帧头、循环冗余校验（CRC）字段和帧结束（EOF）分隔符，如图4所示。
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0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+---------------------------------------------------------------+
| FC PW Control Word |
+---------------------------------------------------------------+
| FC Encapsulation Header |
+---------------+-----------------------------------------------+
| SOF Code | Reserved |
+---------------+-----------------------------------------------+
| |
+----- FC Frame ----+
| |
+---------------------------------------------------------------+
| CRC |
+---------------+-----------------------------------------------+
| EOF Code | Reserved |
+---------------+-----------------------------------------------+
1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+---------------------------------------------------------------+
| FC PW Control Word |
+---------------------------------------------------------------+
| FC Encapsulation Header |
+---------------+-----------------------------------------------+
| SOF Code | Reserved |
+---------------+-----------------------------------------------+
| |
+----- FC Frame ----+
| |
+---------------------------------------------------------------+
| CRC |
+---------------+-----------------------------------------------+
| EOF Code | Reserved |
+---------------+-----------------------------------------------+
Figure 4 - FC Frame (SOF/Data/CRC/EOF) Encapsulation in PW Packet
Figure 4 - FC Frame (SOF/Data/CRC/EOF) Encapsulation in PW Packet
The SOF and EOF frame delimiters are each encoded into a single octet as specified in [RFC3643], except that the codes for delimiters that apply only to FC service class 4 (SOFi4, SOFc4, SOFn4, EOFdt, EOFdti, EOFrt, and EOFrti -- see [FC-FS-2]) MUST NOT be used.
SOF和EOF帧定界符均按照[RFC3643]中的规定编码为单个八位字节，但不得使用仅适用于FC服务类别4（SOFi4、SOFc4、SOFn4、EOFdt、EOFdti、EOFrt和EOFrti——参见[FC-FS-2]）的定界符代码。
The CRC in the frame is obtained directly from the FC attachment channel, so that the PW PE is not required to recalculate the CRC or to check the CRC in the received frame. The CRC will be checked by the FC port that receives the frame, ensuring that coverage is provided for data errors that occur between the PW endpoints. This CRC behavior differs from the Frame Check Sequence (FCS) retention technique for PWs defined in [RFC4720], which states that "as usual, the FCS MUST be examined at the ingress PE, and errored frames MUST be discarded".
帧中的CRC直接从FC连接信道获得，因此PW PE无需重新计算CRC或检查接收帧中的CRC。接收帧的FC端口将检查CRC，确保为PW端点之间发生的数据错误提供覆盖。该CRC行为不同于[RFC4720]中定义的PWs帧检查序列（FCS）保留技术，该技术规定“通常，必须在入口PE检查FCS，并且必须丢弃错误帧”。
FC Primitive Sequences and Primitive Signals are FC Ordered Sets. On an 8b/10b-coded FC link, an Ordered Set consists of four 10b characters, starting with the K28.5 character, followed by three Dxx.y data characters. All FC Ordered Sets start with a K28.5 control character, but the three following Dxx.y data characters differ depending on the Ordered Set. A Kxx.y control character has a different 10b code from the corresponding Dxx.y data character but uses the same 8b code (e.g., K28.5 and D28.5 both use the 8b code 0xBC). Here are two examples of Ordered Sets:
FC基元序列和基元信号是FC有序集。在8b/10b编码FC链路上，有序集由四个10b字符组成，从K28.5字符开始，后跟三个Dxx.y数据字符。所有FC有序集均以K28.5控制字符开头，但以下三个Dxx.y数据字符因有序集而异。Kxx.y控制字符与对应的Dxx.y数据字符具有不同的10b代码，但使用相同的8b代码（例如，K28.5和D28.5都使用8b代码0xBC）。以下是两个有序集的示例：
o Idle (IDLE) is K28.5 - D21.4 - D21.5 - D21.5. This FC Primitive Signal is sent when the FC link is idle; it is suppressed by the FC PW NSP and not sent over the WAN.
o 怠速（Idle）为K28.5-D21.4-D21.5-D21.5。当FC链路空闲时发送该FC原始信号；它被FC PW NSP抑制，不通过WAN发送。
o Link Reset Response (LRR) is K28.5 - D21.1 - D31.5 - D9.2. This FC Primitive Sequence is used as part of FC link initialization and recovery.
o 链路复位响应（LRR）为K28.5-D21.1-D31.5-D9.2。此FC原语序列用作FC链路初始化和恢复的一部分。
Each Ordered Set is encapsulated in a PW packet containing the encoded K28.5 control character [FC-BB-5/AM1], followed by three encoded data characters, as shown in Figure 5.
每个有序集封装在一个PW数据包中，该数据包包含编码的K28.5控制字符[FC-BB-5/AM1]，后跟三个编码的数据字符，如图5所示。
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0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+---------------------------------------------------------------+
| FC PW Control Word |
+---------------------------------------------------------------+
| FC Encapsulation Header |
+---------------+---------------+---------------+---------------+
| K28.5 | Dxx.y | Dxx.y | Dxx.y |
+---------------+---------------+---------------+---------------+
| |
+---- ----+
| |
+---------------+---------------+---------------+---------------+
| K28.5 | Dxx.y | Dxx.y | Dxx.y |
+---------------+---------------+---------------+---------------+
1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+---------------------------------------------------------------+
| FC PW Control Word |
+---------------------------------------------------------------+
| FC Encapsulation Header |
+---------------+---------------+---------------+---------------+
| K28.5 | Dxx.y | Dxx.y | Dxx.y |
+---------------+---------------+---------------+---------------+
| |
+---- ----+
| |
+---------------+---------------+---------------+---------------+
| K28.5 | Dxx.y | Dxx.y | Dxx.y |
+---------------+---------------+---------------+---------------+
Figure 5 - FC Ordered Sets Encapsulation in PW Packet
图5-PW数据包中的FC有序集封装
The K28.5 10b control character received from the PE's attached FC link is encoded for the FC PW as its 8b counterpart (0xBC). Because the same 8b value (0xBC) is used to encode a D28.5 data word, the receiving FC PW PE:
从PE连接的FC链路接收的K28.5 10b控制字符被编码为FC PW的8b对应项（0xBC）。由于使用相同的8b值（0xBC）对D28.5数据字进行编码，因此接收FC PW PE：
o MUST check for presence of an 8b K28.5 value (0xBC) at the start of each Ordered Set (see Figure 5) and MUST send that value as a 10b K28.5 character on the attached FC link.
o 必须检查每个有序集（见图5）开头是否存在8b K28.5值（0xBC），并且必须在连接的FC链路上以10b K28.5字符的形式发送该值。
o MUST send the following three Dxx.y 8b values as Dxx.y 10b characters on the attached FC link and MUST NOT send any of these Dxx.y 8b values as 10b Kxx.y characters on the attached FC link.
o 必须在连接的FC链路上以Dxx.y 10b字符的形式发送以下三个Dxx.y 8b值，并且不得在连接的FC链路上以10b Kxx.y字符的形式发送任何这些Dxx.y 8b值。
A PW packet may contain one or more encoded FC Ordered Sets [FC-BB-5/AM1]. The Length field in the FC PW Control Word is used to indicate the packet length when the PW packet contains multiple Ordered Sets. For this reason, FC PW packets that contain FC Ordered
PW数据包可以包含一个或多个编码的FC有序集[FC-BB-5/AM1]。FC PW控制字中的长度字段用于指示PW数据包包含多个有序集时的数据包长度。因此，包含FC的FC PW数据包是有序的
Sets MUST NOT be larger than 60 octets (8 octets of header words plus at most 13 Ordered Sets), in order to ensure that the Length field contains a non-zero value (see [RFC4385]).
为确保长度字段包含非零值（请参见[RFC4385]），集合不得大于60个八位字节（标题字的8个八位字节加上最多13个有序集合）。
Idle Primitive Signals could be carried over the PW in the same manner as Primitive Sequences. However, [FC-BB-5/AM1] requires that Idle Primitive Signals be dropped by the Ingress PE and regenerated by the egress PE in order to reduce bandwidth consumption (see [FC-BB-5/AM1] for further details).
空闲原始信号可以以与原始序列相同的方式在PW上传输。然而，[FC-BB-5/AM1]要求入口PE丢弃空闲原始信号，并由出口PE重新生成，以减少带宽消耗（有关更多详细信息，请参阅[FC-BB-5/AM1]）。
The egress PE extracts the Primitive Sequence or Primitive Signal from the received PW packet. For a Primitive Sequence, the PE continues transmitting the same FC Ordered Set to its attached FC port until an FC frame or another Ordered Set is received over the PW; see Section 1.2 above for discussion of ingress PE transmission behavior for Primitive Sequences. A Primitive Signal is sent once, except that Idle Primitive Signals are sent continuously when there is nothing else to send.
出口PE从接收到的PW分组中提取原始序列或原始信号。对于原始序列，PE继续将相同的FC有序集发送到其连接的FC端口，直到通过PW接收到FC帧或另一有序集；有关原始序列的入口PE传输行为的讨论，请参见上文第1.2节。一个基本信号只发送一次，除了空闲的基本信号在没有其他信号发送时连续发送。
FC PW control frames are transported over the PW by encapsulating each frame in a PW packet with PT=6 in the Control Word. FC PW control frame payloads are generated and terminated by the corresponding FC entity. FC PW control frames are used for FC PW flow control (ASFC), ping, and transmission of error indications. [FC-BB-5/AM1] specifies the generation and processing of FC PW control frames. FC PW control frames are always shorter than 64 octets, and hence the Length field in the FC Control Word indicates their length.
FC PW控制帧通过PW传输，方法是将每个帧封装在控制字中PT=6的PW包中。FC PW控制帧有效载荷由相应的FC实体生成和终止。FC PW控制帧用于FC PW流量控制（ASFC）、ping和传输错误指示。[FC-BB-5/AM1]指定FC PW控制帧的生成和处理。FC PW控制帧始终短于64个八位字节，因此FC控制字中的长度字段指示其长度。
1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+---------------------------------------------------------------+
| FC PW Control Word |
+---------------------------------------------------------------+
| FC Encapsulation Header |
+---------------------------------------------------------------+
| |
+----- FC PW Control Frame ----+
| |
+---------------------------------------------------------------+
1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+---------------------------------------------------------------+
| FC PW Control Word |
+---------------------------------------------------------------+
| FC Encapsulation Header |
+---------------------------------------------------------------+
| |
+----- FC PW Control Frame ----+
| |
+---------------------------------------------------------------+
Figure 6 - FC PW Control Frame Encapsulation in PW Packet
图6-PW数据包中的FC PW控制帧封装
PW failures are detected through PW signaling failure, PW status notifications as defined in [RFC4447], or PW Operations, Administration, and Maintenance (OAM) mechanisms and MUST be mapped to emulated signal failure indications. Sending the FC link failure indication to its attached FC link is performed by the NSP, as defined by [FC-BB-5/AM1].
PW故障通过PW信号故障、[RFC4447]中定义的PW状态通知或PW操作、管理和维护（OAM）机制检测，并且必须映射到模拟信号故障指示。按照[FC-BB-5/AM1]的定义，NSP将FC链路故障指示发送至其连接的FC链路。
[RFC4447] specifies the use of the MPLS Label Distribution Protocol (LDP) as a protocol for setting up and maintaining pseudowires. This section describes the use of specific fields and error codes used to control FC PW.
[RFC4447]指定使用MPLS标签分发协议（LDP）作为建立和维护伪线的协议。本节介绍用于控制FC PW的特定字段和错误代码的使用。
The PW Type field in the PWid Forwarding Equivalence Class (FEC) element and PW generalized ID FEC elements MUST be set to the "FC Port Mode" value in Section 8.
PWid转发等价类（FEC）元素和PW通用ID FEC元素中的PW类型字段必须设置为第8节中的“FC端口模式”值。
The Control Word is REQUIRED for FC pseudowires. Therefore, the C-Bit in the PWid FEC element and PW generalized ID FEC elements MUST be set. If the C-Bit is not set, the pseudowire MUST NOT be established, and a Label Release MUST be sent with an "Illegal C-Bit" status code [RFC4447].
FC伪导线需要控制字。因此，必须设置PWid FEC元素和PW广义ID FEC元素中的C位。如果未设置C位，则不得建立伪线，并且必须发送带有“非法C位”状态代码的标签释放[RFC4447]。
The Fragmentation Indicator (Parameter ID = 0x09) is specified in [RFC4446], and its usage is defined in [RFC4623]. Since fragmentation is not used in FC PW, the fragmentation indicator parameter MUST be omitted from the Interface Parameter Sub-TLV.
碎片指示符（参数ID=0x09）在[RFC4446]中指定，其用法在[RFC4623]中定义。由于FC PW中未使用碎片，因此必须从接口参数Sub TLV中省略碎片指示器参数。
The Interface MTU Parameter (Parameter ID = 0x01) is specified in [RFC4447]. Since all FC interfaces have the same MTU, this parameter MUST be omitted from the Interface Parameter Sub-TLV.
[RFC4447]中指定了接口MTU参数（参数ID=0x01）。由于所有FC接口都具有相同的MTU，因此必须从接口参数Sub TLV中省略此参数。
The FCS Retention Indicator (Parameter ID = 0x0A) is specified in [RFC4720]. Since the CRC treatment defined in this document differs from one that is specified in [RFC4720], this parameter MUST be omitted from the Interface Parameter Sub-TLV.
[RFC4720]中规定了FCS保留指示器（参数ID=0x0A）。由于本文件中定义的CRC处理不同于[RFC4720]中规定的CRC处理，因此必须从接口参数Sub TLV中省略此参数。
Correct Fibre Channel link operation requires that the FC link latency between CE1 and CE2 (refer to Figure 1) be:
正确的光纤通道链路操作要求CE1和CE2之间的FC链路延迟（参见图1）为：
o no more than one-half of the R_T_TOV (Receiver Transmitter Timeout Value, default value: 100 milliseconds) of the attached devices for Primitive Sequences;
o 不超过原始序列所连接设备的R_T_TOV（接收器-发射器超时值，默认值：100毫秒）的一半；
o no more than one-half of the E_D_TOV (Error Detect Timeout Value, default value: 2 seconds) of the attached devices for frames; and
o 不超过所连接设备用于帧的E_D_TOV（错误检测超时值，默认值：2秒）的一半；和
o within the R_A_TOV (Resource Allocation Timeout Value, default value: 10 seconds) of the attached fabric(s), if any. The FC standards require that the E_D_TOV value for each FC link be set so that the R_A_TOV value for the fabric is respected when the worst-case latency occurs for each link (see [FC-FS-2]).
o 在连接的结构（如果有）的R_A_TOV（资源分配超时值，默认值：10秒）内。FC标准要求设置每个FC链路的E_D_TOV值，以便在每个链路出现最坏情况延迟时，结构的R_A_TOV值得到遵守（请参见[FC-FS-2]）。
An FC PW MUST adhere to these three timing requirements and MUST NOT be used in environments where high or variable latency may cause these requirements to be violated.
FC PW必须遵守这三个定时要求，并且不得在高延迟或可变延迟可能导致违反这些要求的环境中使用。
These three timeout values are ordered (R_T_TOV < E_D_TOV < R_A_TOV), so adherence to one-half of R_T_TOV for all FC PW traffic is sufficient. See [FC-FS-2] for definitions of the FC timeout values.
这三个超时值是有序的（R_T_-TOV<E_-D_-TOV<R_-A_-TOV），因此对于所有FC PW流量，遵守R_-T_-TOV的一半就足够了。有关FC超时值的定义，请参见[FC-FS-2]。
The R_T_TOV is used by the FC link initialization protocol. If an FC PW's latency exceeds one-half R_T_TOV, initialization of the FC link that is encapsulated by the FC PW may fail, leaving that FC link in a non-operational state.
FC链路初始化协议使用R_T_TOV。如果FC PW的延迟超过R_T__TOV的一半，则由FC PW封装的FC链路的初始化可能会失败，使该FC链路处于非操作状态。
The E_D_TOV is used to detect failures of operational FC links. If an FC PW's latency exceeds the one-half E_D_TOV requirement, the FC link that is encapsulated by the FC PW may fail. The usual FC response to such a link failure is to attempt to recover the FC link by initializing it. That initialization will also fail if the FC PW latency exceeds one-half R_T_TOV (a tighter requirement).
E_D_TOV用于检测运行FC链路的故障。如果FC PW的延迟超过一半E_D_TOV要求，则由FC PW封装的FC链路可能会失败。FC对此类链路故障的通常响应是尝试通过初始化来恢复FC链路。如果FC PW延迟超过一半R_T_TOV（更严格的要求），初始化也将失败。
The R_A_TOV is used to determine when FC communication resources (e.g., values that identify FC frames) may be reused. If an FC PW's violation of the one-half E_D_TOV requirement is sufficient to also cause the FC fabric to violate the R_A_TOV requirement, then FC reuse of frame identification values after an R_A_TOV timeout may result in multiple FC frames with the same identification values, causing incorrect Fibre Channel operation. For example, if two such frames are swapped between I/O operations, the result may corrupt data in the I/O operations.
R_A_TOV用于确定何时可以重用FC通信资源（例如，识别FC帧的值）。如果FC PW违反一半E_D_TOV要求足以导致FC结构违反R_A_TOV要求，则在R_A_TOV超时后FC重用帧标识值可能会导致多个具有相同标识值的FC帧，从而导致光纤通道操作不正确。例如，如果在I/O操作之间交换两个这样的帧，则结果可能会损坏I/O操作中的数据。
The PING and PING_ACK FC PW control frames defined in Section 6.4.7 of [FC-BB-5/AM1] SHOULD be used to measure the current FC pseudowire latency between the Customer Edge (CE) devices. If the measured latency violates any of the timing requirements, then the FC PW PE MUST generate a WAN Down event as specified in [FC-BB-5/AM1].
[FC-BB-5/AM1]第6.4.7节中定义的PING和PING_ACK FC PW控制帧应用于测量客户边缘（CE）设备之间的当前FC伪线延迟。如果测得的延迟违反任何定时要求，则FC PW PE必须生成[FC-BB-5/AM1]中规定的WAN关闭事件。
The WAN Down event causes the PE to continuously send NOS (an FC Primitive Sequence) on the native FC link to the FC port at the other end of that link (typically an E_Port on a switch in this case).
WAN关闭事件导致PE在本机FC链路上将NOS（FC基本序列）连续发送到该链路另一端的FC端口（在这种情况下，通常是交换机上的E_端口）。
This immediately causes the FC link that is carried by the PW to become non-operational, halting transmission of FC traffic. However, it is not necessary to tear down the pseudowire itself in this situation (e.g., destroy the MPLS path set up by LDP).
这会立即导致PW承载的FC链路变得不工作，停止FC通信量的传输。但是，在这种情况下，不必拆除伪线本身（例如，破坏LDP设置的MPLS路径）。
The Transparent FC-BB initialization state machine in [FC-BB-5/AM1] specifies the protocol used to attempt to recover from a WAN Down event (i.e., bring the WAN back up). If that protocol brings the WAN back up, FC traffic will resume and the standard FC link recovery protocol will bring the encapsulated FC link back up. If the previous pseudowire was destroyed, attempts will be made to re-establish the path via LDP as part of recovering from the WAN Down event. If the PW round-trip latency remains above R_T_TOV, the initialization protocol for the FC PW will repeatedly time out in attempting to recover from the WAN Down event, preventing recovery of the FC link carried by the PW; see [FC-BB-5/AM1].
[FC-BB-5/AM1]中的透明FC-BB初始化状态机指定了用于尝试从WAN关闭事件中恢复（即使WAN恢复）的协议。如果该协议使WAN恢复，FC通信将恢复，标准FC链路恢复协议将使封装的FC链路恢复。如果先前的伪线被破坏，将尝试通过LDP重新建立路径，作为从WAN关闭事件恢复的一部分。如果PW往返延迟保持在R_T_TOV以上，FC PW的初始化协议将在尝试从WAN关闭事件中恢复时重复超时，从而阻止恢复PW承载的FC链路；见[FC-BB-5/AM1]。
The FC PW is an MPLS pseudowire; for MPLS pseudowire security considerations, see the security considerations sections of [RFC3985] and [RFC4385].
FC PW是MPLS伪线；有关MPLS伪线安全注意事项，请参阅[RFC3985]和[RFC4385]的安全注意事项部分。
The protocols used to implement security in a Fibre Channel fabric are defined in [FC-SP]. These protocols operate at higher layers of the FC hierarchy and are transparent to the FC PW.
[FC-SP]中定义了用于在光纤通道结构中实现安全性的协议。这些协议在FC层次结构的更高层运行，对FC PW是透明的。
The FC timing requirements (see Section 5) create an exposure of the FC PW to inserted latency. Injection of latency sufficient to cause the round-trip time for an FC PW to exceed R_T_TOV (default: 100 ms) may cause the FC PW to fail in an active fashion because the FC link initialization protocol repeatedly times out. OAM functionality for deployed FC PWs SHOULD monitor for persistence of this situation and respond accordingly (e.g., shut down the FC PW in order to avoid wasting WAN bandwidth on an FC PW whose FC link cannot be successfully initialized due to excessive latency).
FC定时要求（见第5节）造成FC PW暴露于插入延迟。注入足以导致FC PW的往返时间超过R_T_TOV（默认值：100 ms）的延迟可能导致FC PW以活动方式失败，因为FC链路初始化协议重复超时。已部署FC PW的OAM功能应监控这种情况的持续性，并做出相应的响应（例如，关闭FC PW以避免在FC PW上浪费WAN带宽，该FC PW的FC链路由于延迟过大而无法成功初始化）。
FC PW allows the transparent transport of FC traffic between Fibre Channel ports while saving network bandwidth by removing FC Idle Primitive Signals and reducing the number of FC Primitive Sequences.
FC PW允许光纤通道端口之间的FC流量透明传输，同时通过删除FC空闲基本信号和减少FC基本序列的数量来节省网络带宽。
o The pair of CE devices operates as if they were directly connected by an FC link. In particular, they react to Primitive Sequences on their local FC links as specified by the FC standards.
o 这对CE设备的操作就像它们通过FC链路直接连接一样。特别是，它们对FC标准规定的本地FC链路上的原始序列作出反应。
o The FC PW carries only FC data frames, FC Primitive Signals, and a subset of the copies of an FC Primitive Sequence. Idle Primitive Signals are suppressed, and long streams of the same Primitive Sequence are reduced over the PW, thus saving bandwidth.
o FC PW仅携带FC数据帧、FC基元信号和FC基元序列副本的子集。空闲基元信号被抑制，并且相同基元序列的长流在PW上被减少，从而节省带宽。
o The PW PE MUST generate Idle Primitive Signals to the attached FC link when there is no other traffic to transmit on the attached FC link [FC-FS-2].
o 当连接的FC链路上没有其他通信要传输时，PW PE必须向连接的FC链路生成空闲原始信号[FC-FS-2]。
o The PW PE MUST send Primitive Sequences continuously to the attached FC port, as required by the FC standards [FC-FS-2].
o PW PE必须按照FC标准[FC-FS-2]的要求，连续向连接的FC端口发送基本序列。
FC PW traffic should only traverse MPLS networks that are provisioned based on traffic engineering to provide dedicated bandwidth for FC PW traffic. The MPLS network should enforce ingress traffic policing so that delivery of FC PW traffic can be assured. To extend FC across a network that does not satisfy these requirements, FCIP SHOULD be used instead of an FC PW (see [RFC3821] and [FC-BB-6]).
FC PW流量应仅通过基于流量工程配置的MPLS网络，以便为FC PW流量提供专用带宽。MPLS网络应实施入口流量监控，以便确保FC PW流量的交付。要在不满足这些要求的网络上扩展FC，应使用FCIP而不是FC PW（参见[RFC3821]和[FC-BB-6]）。
This document does not provide any mechanisms for protecting an FC PW against network outages. As a consequence, resilience of the emulated FC service to such outages is dependent upon the underlying MPLS network, which should be protected against failures. When a network outage is detected, the PE SHOULD use a WAN Down event (as specified in [FC-BB-5/AM1]) to convey the PW status to the CE and enable faster outage handling.
本文件未提供任何保护FC PW免受网络中断影响的机制。因此，模拟FC服务对此类中断的恢复能力取决于底层MPLS网络，该网络应受到故障保护。当检测到网络中断时，PE应使用WAN关闭事件（如[FC-BB-5/AM1]中所述）将PW状态传达给CE，并实现更快的中断处理。
IANA has assigned a new MPLS Pseudowire (PW) type as follows:
IANA分配了一种新的MPLS伪线（PW）类型，如下所示：
PW type Description Reference
-------- -------------- ----------
0x001F FC Port Mode RFC 6307
PW type Description Reference
-------- -------------- ----------
0x001F FC Port Mode RFC 6307
IANA has reserved the following Pseudowire Interface Parameters Sub-TLV Types. These Sub-TLV types were used for the FC PW Selective Retransmission protocol, which the PWE3 working group has decided to eliminate. This action prevents future use of these values for other purposes, as there is at least one implementation of the Selective Retransmission protocol that has been deployed.
IANA已保留以下伪线接口参数子TLV类型。这些子TLV类型用于FC PW选择性重传协议，PWE3工作组已决定取消该协议。此操作防止将来将这些值用于其他目的，因为至少部署了一个选择性重传协议的实现。
Parameter ID Length Description Reference
--------- --------- ----------- ---------
0x12 Reserved RFC 6307
0x13 Reserved RFC 6307
0x14 Reserved RFC 6307
0x15 Reserved RFC 6307
Parameter ID Length Description Reference
--------- --------- ----------- ---------
0x12 Reserved RFC 6307
0x13 Reserved RFC 6307
0x14 Reserved RFC 6307
0x15 Reserved RFC 6307
Previous versions of this document were authored by Moran Roth, Ronen Solomon, and Munefumi Tsurusawa; their efforts and contributions are gratefully acknowledged. The authors would like to thank Stewart Bryant, Elwyn Davies, Steve Hanna, Dave Peterson, Yaakov Stein, Alexander Vainshtein, and the members of the IESG for helpful comments on this document.
本文件的早期版本由Moran Roth、Ronen Solomon和Munefumi Tsurusawa编写；感谢他们的努力和贡献。作者要感谢Stewart Bryant、Elwyn Davies、Steve Hanna、Dave Peterson、Yaakov Stein、Alexander Vainstein和IESG成员对本文件的有益评论。
The protocol specified in this document is intended to be used in conjunction with the Fibre Channel pseudowire portion of the FC-BB-5 Amendment 1 specification developed by INCITS Technical Committee T11. The authors would like to thank the members of both the IETF and T11 organizations who have supported and contributed to this work.
本文件中规定的协议旨在与INCITS技术委员会T11制定的FC-BB-5修订件1规范的光纤通道伪线部分结合使用。作者要感谢IETF和T11组织的成员，感谢他们对这项工作的支持和贡献。
[FC-BB-5/AM1] "Fibre Channel - Backbone-5 / Amendment 1", INCITS 462-2010/AM 1-2012, June 2012.
[FC-BB-5/AM1]“光纤通道主干网-5/修改件1”，INCITS 462-2010/AM 1-2012，2012年6月。
[FC-FS-2] "Fibre Channel - Framing and Signaling-2 (FC-FS-2)", ANSI INCITS 424:2007, August 2007.
[FC-FS-2]“光纤通道-帧和信令-2（FC-FS-2）”，ANSI INCITS 424:2007，2007年8月。
[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。
[RFC3643] Weber, R., Rajagopal, M., Travostino, F., O'Donnell, M., Monia, C., and M. Merhar, "Fibre Channel (FC) Frame Encapsulation", RFC 3643, December 2003.
[RFC3643]韦伯，R.，拉贾戈帕尔，M.，特拉沃斯蒂诺，F.，O'Donnell，M.，莫尼亚，C.，和M.梅哈尔，“光纤通道（FC）帧封装”，RFC 36432003年12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。
[RFC4446] Martini, L., "IANA Allocations for Pseudowire Edge to Edge Emulation (PWE3)", BCP 116, RFC 4446, April 2006.
[RFC4446]Martini，L.，“伪线边到边仿真（PWE3）的IANA分配”，BCP 116，RFC 4446，2006年4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。
[RFC4623] Malis, A. and M. Townsley, "Pseudowire Emulation Edge-to-Edge (PWE3) Fragmentation and Reassembly", RFC 4623, August 2006.
[RFC4623]Malis，A.和M.Townsley，“伪线仿真边到边（PWE3）碎片化和重组”，RFC 46232006年8月。
[RFC4720] Malis, A., Allan, D., and N. Del Regno, "Pseudowire Emulation Edge-to-Edge (PWE3) Frame Check Sequence Retention", RFC 4720, November 2006.
[RFC4720]Malis，A.，Allan，D.，和N.Del Regno，“伪线仿真边到边（PWE3）帧检查序列保留”，RFC 4720，2006年11月。
[FC-BB-6] "Fibre Channel Backbone-6" (FC-BB-6), T11 Project 2159-D, Rev 1.04, Work in Progress, January 2012.
[FC-BB-6]“光纤通道主干网-6”（FC-BB-6），T11项目2159-D，修订版1.04，在建工程，2012年1月。
[FC-SP] "Fibre Channel - Security Protocols" (FC-SP), ANSI INCITS 426:2007, February 2007.
[FC-SP]“光纤通道-安全协议”（FC-SP），ANSI INCITS 426:2007，2007年2月。
[RFC3821] Rajagopal, M., Rodriguez, E., and R. Weber, "Fibre Channel Over TCP/IP (FCIP)", RFC 3821, July 2004.
[RFC3821]Rajagopal，M.，Rodriguez，E.，和R.Weber，“TCP/IP上的光纤通道（FCIP）”，RFC 38212004年7月。
[RFC4717] Martini, L., Jayakumar, J., Bocci, M., El-Aawar, N., Brayley, J., and G. Koleyni, "Encapsulation Methods for Transport of Asynchronous Transfer Mode (ATM) over MPLS Networks", RFC 4717, December 2006.
[RFC4717]Martini，L.，Jayakumar，J.，Bocci，M.，El-Aawar，N.，Brayley，J.，和G.Koleyni，“MPLS网络上异步传输模式（ATM）传输的封装方法”，RFC 47172006年12月。
[T11] INCITS Technical Committee T11, http://www.t11.org, January 2011.
[T11]INCITS技术委员会T11，http://www.t11.org，2011年1月。
Authors' Addresses
作者地址
David L. Black (editor) EMC Corporation 176 South Street Hopkinton, MA 01748 USA Phone: +1 (508) 293-7953 EMail: david.black@emc.com
David L.Black（编辑）美国马萨诸塞州霍普金顿南街176号EMC公司电话：+1（508）293-7953电子邮件：David。black@emc.com
Linda Dunbar (editor) Huawei Technologies 1700 Alma Drive, Suite 500 Plano, TX 75075 USA Phone: +1 (972) 543-5849 EMail: ldunbar@huawei.com
Linda Dunbar（编辑）华为技术有限公司德克萨斯州普莱诺阿尔玛大道1700号500室75075美国电话：+1（972）543-5849电子邮件：ldunbar@huawei.com
Moran Roth Infinera Corporation 169 Java Drive Sunnyvale, CA 94089 USA Phone: (408) 572-5200 EMail: MRoth@infinera.com
美国加利福尼亚州桑尼维尔市爪哇大道169号莫兰·罗斯·英菲内拉公司94089电话：（408）572-5200电子邮件：MRoth@infinera.com
Ronen Solomon Orckit-Corrigent Systems 126, Yigal Alon st. Tel Aviv Israel Phone: +972-3-6945316 EMail: ronens@corrigent.com
Ronen Solomon Orkit Corrigent Systems 126，以色列特拉维夫Yigal Alon st.电话：+972-3-6945316电子邮件：ronens@corrigent.com