Network Working Group L. Martini, Ed.
Request for Comments: 4905 E. Rosen, Ed.
Category: Historic Cisco Systems, Inc.
N. El-Aawar, Ed.
Level 3 Communications, LLC
June 2007
Network Working Group L. Martini, Ed.
Request for Comments: 4905 E. Rosen, Ed.
Category: Historic Cisco Systems, Inc.
N. El-Aawar, Ed.
Level 3 Communications, LLC
June 2007
Encapsulation Methods for Transport of Layer 2 Frames over MPLS Networks
MPLS网络上第2层帧传输的封装方法
Status of This Memo
关于下段备忘
This memo defines a Historic Document for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited.
此备忘录定义了互联网社区的历史文档。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。
Copyright Notice
版权公告
Copyright (C) The IETF Trust (2007).
版权所有（C）IETF信托基金（2007年）。
Abstract
摘要
This document describes methods for encapsulating the Protocol Data Units (PDUs) of layer 2 protocols such as Frame Relay, Asynchronous Transfer Mode (ATM), or Ethernet for transport across an MPLS network. This document describes the so-called "draft-martini" protocol, which has since been superseded by the Pseudowire Emulation Edge to Edge Working Group specifications described in RFC 4447 and related documents.
本文档描述了封装第2层协议（如帧中继、异步传输模式（ATM）或以太网）的协议数据单元（PDU）的方法，以便在MPLS网络上传输。本文件描述了所谓的“马提尼草案”协议，该协议已被RFC 4447和相关文件中描述的伪线仿真边到边工作组规范所取代。
Table of Contents
目录
1. Introduction ....................................................3
2. Specification of Requirements ...................................3
3. Special Note ....................................................4
4. General Encapsulation Method ....................................4
4.1. The Control Word ...........................................4
4.1.1. Setting the Sequence Number .........................5
4.1.2. Processing the Sequence Number ......................6
4.2. MTU Requirements ...........................................6
5. Protocol-Specific Details .......................................7
5.1. Frame Relay ................................................7
5.2. ATM ........................................................8
5.2.1. ATM AAL5 CPCS-SDU Mode ..............................9
5.2.2. ATM Cell Mode ......................................10
5.2.3. OAM Cell Support ...................................12
5.2.4. CLP bit to Quality of Service Mapping ..............12
5.3. Ethernet VLAN .............................................12
5.4. Ethernet ..................................................12
5.5. High-Level Data Link Control (HDLC) .......................13
5.6. PPP .......................................................13
6. Using an MPLS Label as the Demultiplexer Field .................13
6.1. MPLS Shim EXP Bit Values ..................................14
6.2. MPLS Shim S Bit Value .....................................14
6.3. MPLS Shim TTL Values ......................................14
7. Security Considerations ........................................14
8. Normative References ...........................................14
9. Informative References .........................................16
10. Co-Authors ....................................................16
1. Introduction ....................................................3
2. Specification of Requirements ...................................3
3. Special Note ....................................................4
4. General Encapsulation Method ....................................4
4.1. The Control Word ...........................................4
4.1.1. Setting the Sequence Number .........................5
4.1.2. Processing the Sequence Number ......................6
4.2. MTU Requirements ...........................................6
5. Protocol-Specific Details .......................................7
5.1. Frame Relay ................................................7
5.2. ATM ........................................................8
5.2.1. ATM AAL5 CPCS-SDU Mode ..............................9
5.2.2. ATM Cell Mode ......................................10
5.2.3. OAM Cell Support ...................................12
5.2.4. CLP bit to Quality of Service Mapping ..............12
5.3. Ethernet VLAN .............................................12
5.4. Ethernet ..................................................12
5.5. High-Level Data Link Control (HDLC) .......................13
5.6. PPP .......................................................13
6. Using an MPLS Label as the Demultiplexer Field .................13
6.1. MPLS Shim EXP Bit Values ..................................14
6.2. MPLS Shim S Bit Value .....................................14
6.3. MPLS Shim TTL Values ......................................14
7. Security Considerations ........................................14
8. Normative References ...........................................14
9. Informative References .........................................16
10. Co-Authors ....................................................16
In an MPLS network, it is possible to use control protocols such as those specified in [RFC4906] to set up "emulated virtual circuits" that carry the Protocol Data Units of layer 2 protocols across the network. A number of these emulated virtual circuits (VCs) may be carried in a single tunnel. This requires, of course, that the layer 2 PDUs be encapsulated. We can distinguish three layers of this encapsulation:
在MPLS网络中，可以使用[RFC4906]中规定的控制协议来建立“仿真虚拟电路”，在网络上传输第2层协议的协议数据单元。这些仿真虚拟电路（VCs）中的许多可以在单个隧道中进行。当然，这需要封装第2层PDU。我们可以区分这种封装的三层：
- the "tunnel header", which contains the information needed to transport the PDU across the MPLS network; this header belongs to the tunneling protocol, e.g., MPLS, Generic Routing Encapsulation (GRE), and Layer 2 Tunneling Protocol (L2TP).
- “隧道头”，其中包含通过MPLS网络传输PDU所需的信息；此标头属于隧道协议，例如MPLS、通用路由封装（GRE）和第2层隧道协议（L2TP）。
- the "demultiplexer field", which is used to distinguish individual emulated virtual circuits within a single tunnel; this field must be understood by the tunneling protocol as well; it may be, e.g., an MPLS label or a GRE key field.
- “解复用器字段”，用于区分单个隧道内的单个仿真虚拟电路；隧道协议也必须理解该字段；例如，它可以是MPLS标签或GRE密钥字段。
- the "emulated VC encapsulation", which contains the information about the enclosed layer 2 PDU that is necessary in order to properly emulate the corresponding layer 2 protocol.
- “仿真VC封装”，其中包含有关封闭的第2层PDU的信息，这是正确仿真相应的第2层协议所必需的。
This document specifies the emulated VC encapsulation for a number of layer 2 protocols. Although different layer 2 protocols require different information to be carried in this encapsulation, an attempt has been made to make the encapsulation as common as possible for all layer 2 protocols.
本文档指定了许多第2层协议的模拟VC封装。尽管不同的第2层协议要求在该封装中携带不同的信息，但已尝试使封装尽可能通用于所有第2层协议。
This document also specifies the way in which the demultiplexer field is added to the emulated VC encapsulation when an MPLS label is used as the demultiplexer field.
本文档还指定了当MPLS标签用作解复用器字段时，将解复用器字段添加到模拟VC封装中的方式。
Quality of service (QoS)-related issues are not discussed in this document.
本文档不讨论与服务质量（QoS）相关的问题。
For the purpose of this document, R1 will be defined as the ingress router, and R2 as the egress router. A layer 2 PDU will be received at R1, encapsulated at R1, transported, decapsulated at R2, and transmitted out of R2.
在本文件中，R1定义为入口路由器，R2定义为出口路由器。第2层PDU将在R1处接收、在R1处封装、在R2处传输、解封装，并从R2处传输出去。
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。
This document describes the so called "draft-martini" protocol, which is used in many deployed implementations. This document and its contents have since been superseded by the Pseudowire Emulation Edge to Edge Working Group specifications: [RFC4447], [RFC4385], [RFC4448], [RFC4717], [RFC4618], [RFC4619], [RFC4553], [RFC4842], and related documents. This document serves as documentation of current implementations, and MUST NOT be used for new implementations. The PWE3 Label Distribution Protocol control protocol document [RFC4447], which is backward compatible with this document, MUST be used for all new implementations of this protocol.
本文档描述了所谓的“draft martini”协议，该协议用于许多已部署的实现中。本文件及其内容已被伪线仿真边到边工作组规范[RFC4447]、[RFC4385]、[RFC4448]、[RFC4717]、[RFC4618]、[RFC4619]、[RFC4553]、[RFC4842]和相关文件所取代。本文档作为当前实施的文档，不得用于新的实施。PWE3标签分发协议控制协议文件[RFC4447]与本文件向后兼容，必须用于本协议的所有新实现。
In most cases, it is not necessary to transport the layer 2 encapsulation across the network; rather, the layer 2 header can be stripped at R1 and reproduced at R2. This is done using information carried in the control word (see below), as well as information that may already have been signaled from R1 to R2.
在大多数情况下，不需要通过网络传输第2层封装；相反，第2层标头可以在R1处剥离，并在R2处复制。这是通过使用控制字中携带的信息（见下文）以及可能已经从R1发送到R2的信息来完成的。
There are three requirements that may need to be satisfied when transporting layer 2 protocols over an MPLS backbone:
在MPLS主干上传输第2层协议时，可能需要满足三个要求：
-i. Sequentiality may need to be preserved.
-一,。可能需要保留顺序性。
-ii. Small packets may need to be padded in order to be transmitted on a medium where the minimum transport unit is larger than the actual packet size.
-二,。为了在最小传输单元大于实际分组大小的介质上传输，可能需要填充小分组。
-iii. Control bits carried in the header of the layer 2 frame may need to be transported.
-iii.可能需要传输层2帧的报头中携带的控制比特。
The control word defined here addresses all three of these requirements. For some protocols, this word is REQUIRED, and for others OPTIONAL. For protocols where the control word is OPTIONAL, implementations MUST support sending no control word, and MAY support sending a control word.
这里定义的控制字解决了所有这三个需求。对于某些协议，这个词是必需的，而对于其他协议，这个词是可选的。对于控制字是可选的协议，实现必须支持不发送控制字，并且可能支持发送控制字。
In all cases, the egress router must be aware of whether the ingress router will send a control word over a specific virtual circuit. This may be achieved by configuration of the routers or by signaling, for example, as defined in [RFC4906].
在所有情况下，出口路由器必须知道入口路由器是否将通过特定虚拟电路发送控制字。这可以通过路由器的配置或通过信令来实现，例如，如[RFC4906]中所定义。
The control word is defined as follows:
控制字的定义如下：
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Rsvd | Flags |0 0| Length | Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Rsvd | Flags |0 0| Length | Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
In the above diagram, the first 4 bits are reserved for future use. They MUST be set to 0 when transmitting, and MUST be ignored upon receipt.
在上图中，前4位保留供将来使用。传输时必须将其设置为0，并且在接收时必须忽略。
The next 4 bits provide space for carrying protocol-specific flags. These are defined in the protocol-specific details below.
接下来的4位提供用于承载协议特定标志的空间。这些在以下特定于协议的详细信息中定义。
The next 2 bits MUST be set to 0 when transmitting.
传输时，下2位必须设置为0。
The next 6 bits provide a length field, which is used as follows: If the packet's length (defined as the length of the layer 2 payload plus the length of the control word) is less than 64 bytes, the length field MUST be set to the packet's length. Otherwise, the length field MUST be set to 0. The value of the length field, if non-zero, can be used to remove any padding. When the packet reaches the service provider's egress router, it may be desirable to remove the padding before forwarding the packet.
接下来的6位提供一个长度字段，其使用如下：如果数据包的长度（定义为第2层有效负载的长度加上控制字的长度）小于64字节，则长度字段必须设置为数据包的长度。否则，长度字段必须设置为0。长度字段的值（如果非零）可用于删除任何填充。当分组到达服务提供商的出口路由器时，可能希望在转发分组之前移除填充。
The next 16 bits provide a sequence number that can be used to guarantee ordered packet delivery. The processing of the sequence number field is OPTIONAL.
接下来的16位提供了一个序列号，可以用来保证有序的数据包传递。序列号字段的处理是可选的。
The sequence number space is a 16-bit, unsigned circular space. The sequence number value 0 is used to indicate an unsequenced packet.
序列号空间是一个16位的无符号循环空间。序号值0用于指示未排序的数据包。
For a given emulated VC, and a pair of routers R1 and R2, if R1 supports packet sequencing, then the following procedures should be used:
对于给定的模拟VC以及一对路由器R1和R2，如果R1支持数据包排序，则应使用以下步骤：
- The initial packet transmitted on the emulated VC MUST use sequence number 1.
- 在模拟VC上传输的初始数据包必须使用序号1。
- Subsequent packets MUST increment the sequence number by 1 for each packet.
- 后续数据包必须将每个数据包的序列号增加1。
- When the transmit sequence number reaches the maximum 16 bit value (65535), the sequence number MUST wrap to 1.
- 当发送序列号达到最大16位值（65535）时，序列号必须换行为1。
If the transmitting router R1 does not support sequence number processing, then the sequence number field in the control word MUST be set to 0.
如果发送路由器R1不支持序列号处理，则控制字中的序列号字段必须设置为0。
If a router R2 supports receive sequence number processing, then the following procedures should be used:
如果路由器R2支持接收序列号处理，则应使用以下步骤：
When an emulated VC is initially set up, the "expected sequence number" associated with it MUST be initialized to 1.
初始设置模拟VC时，与之关联的“预期序列号”必须初始化为1。
When a packet is received on that emulated VC, the sequence number should be processed as follows:
当在模拟VC上接收到数据包时，序列号应按如下方式处理：
- If the sequence number on the packet is 0, then the packet passes the sequence number check.
- 如果数据包上的序列号为0，则数据包通过序列号检查。
- Else if the packet sequence number >= the expected sequence number and the packet sequence number - the expected sequence number < 32768, then the packet is in order.
- 否则，如果数据包序列号>=预期序列号，而数据包序列号-预期序列号<32768，则数据包处于有序状态。
- Else if the packet sequence number < the expected sequence number and the expected sequence number - the packet sequence number >= 32768, then the packet is in order.
- 否则，如果数据包序列号<预期序列号和预期序列号-数据包序列号>=32768，则数据包处于有序状态。
- Otherwise, the packet is out of order.
- 否则，数据包将出现故障。
If a packet passes the sequence number check or is in order, then it can be delivered immediately. If the packet is in order, then the expected sequence number should be set using the algorithm:
如果一个数据包通过了序列号检查或者是有序的，那么它可以立即被传送。如果数据包有序，则应使用以下算法设置预期序列号：
expected_sequence_number := packet_sequence_number + 1 mod 2**16
if (expected_sequence_number = 0) then expected_sequence_number := 1;
expected_sequence_number := packet_sequence_number + 1 mod 2**16
if (expected_sequence_number = 0) then expected_sequence_number := 1;
Packets that are received out of order MAY be dropped or reordered at the discretion of the receiver.
接收方可自行决定丢弃或重新排序无序接收的数据包。
If a router R2 does not support receive sequence number processing, then the sequence number field MAY be ignored.
如果路由器R2不支持接收序列号处理，则序列号字段可能被忽略。
The network MUST be configured with an MTU that is sufficient to transport the largest encapsulation frames. If MPLS is used as the tunneling protocol, for example, this is likely to be 12 or more bytes greater than the largest frame size. Other tunneling protocols may have longer headers and require larger MTUs. If the ingress
网络必须配置足以传输最大封装帧的MTU。例如，如果将MPLS用作隧道协议，则这可能比最大帧大小大12个或更多字节。其他隧道协议可能具有更长的标头，并且需要更大的MTU。如果入口
router determines that an encapsulated layer 2 PDU exceeds the MTU of the tunnel through which it must be sent, the PDU MUST be dropped. If an egress router receives an encapsulated layer 2 PDU whose payload length (i.e., the length of the PDU itself without any of the encapsulation headers) exceeds the MTU of the destination layer 2 interface, the PDU MUST be dropped.
路由器确定封装的第2层PDU超过了它必须通过的隧道的MTU，必须丢弃PDU。如果出口路由器接收到一个封装的第2层PDU，其有效负载长度（即，没有任何封装头的PDU本身的长度）超过目的地第2层接口的MTU，则必须丢弃该PDU。
A Frame Relay PDU is transported without the Frame Relay header or the Frame Check Sequence (FCS). The control word is REQUIRED; however, its use is optional, although desirable. Use of the control word means that the ingress and egress Label Switching Routers (LSRs) follow the procedures below. If an ingress LSR chooses not to use the control word, it MUST set the flags in the control word to 0; if an egress LSR chooses to ignore the control word, it MUST set the Frame Relay control bits to 0.
传输帧中继PDU时不使用帧中继报头或帧检查序列（FCS）。控制字是必需的；然而，它的使用是可选的，尽管是可取的。使用控制字意味着入口和出口标签交换路由器（LSR）遵循以下程序。如果入口LSR选择不使用控制字，则必须将控制字中的标志设置为0；如果出口LSR选择忽略控制字，则必须将帧中继控制位设置为0。
The BECN (Backward Explicit Congestion Notification), FECN (Forward Explicit Congestion Notification), DE (Discard Eligibility), and C/R (Command/Response) bits are carried across the network in the control word. The edge routers that implement this document MAY, when either adding or removing the encapsulation described herein, change the BECN and/or FECN bits from 0 to 1 in order to reflect congestion in the network that is known to the edge routers, and the D/E bit from 0 to 1 to reflect marking from edge policing of the Frame Relay Committed Information Rate. The BECN, FECN, and D/E bits SHOULD NOT be changed from 1 to 0.
BECN（向后显式拥塞通知）、FECN（向前显式拥塞通知）、DE（丢弃合格性）和C/R（命令/响应）位在控制字中通过网络传输。实现本文档的边缘路由器可在添加或移除本文所述的封装时，将BECN和/或FECN位从0更改为1，以反映边缘路由器已知的网络拥塞，以及从0到1的D/E位，以反映帧中继提交信息速率的边缘策略的标记。BECN、FECN和D/E位不应从1更改为0。
The following is an example of a Frame Relay packet:
以下是帧中继分组的示例：
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Rsvd |B|F|D|C| Length | Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Frame Relay PDU |
| " |
| " |
| " |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Rsvd |B|F|D|C| Length | Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Frame Relay PDU |
| " |
| " |
| " |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* B ( BECN ) Bit
* B（BECN）钻头
The ingress router, R1, SHOULD copy the BECN field from the incoming Frame Relay header into this field. The egress router, R2, MUST generate a new BECN field based on the value of the B bit.
入口路由器R1应将BECN字段从传入帧中继报头复制到此字段中。出口路由器R2必须基于B位的值生成新的BECN字段。
* F ( FECN ) Bit
* F（FECN）位
The ingress router, R1, SHOULD copy the FECN field from the incoming Frame Relay header into this field. The egress router, R2, MUST generate a new FECN field based on the value of the F bit.
入口路由器R1应将FECN字段从传入帧中继报头复制到此字段中。出口路由器R2必须基于F位的值生成新的FECN字段。
* D ( DE ) Bit
* D（DE）钻头
The ingress router, R1, SHOULD copy the DE field from the incoming Frame Relay header into this field. The egress router, R2, MUST generate a new DE field based on the value of the D bit.
入口路由器R1应将DE字段从传入帧中继报头复制到此字段中。出口路由器R2必须基于D位的值生成新的DE字段。
If the tunneling protocol provides a field that can be set to specify a Quality of Service, the ingress router, R1, MAY consider the DE bit of the Frame Relay header when determining the value of that field. The egress router MAY then consider the value of this field when queuing the layer 2 PDU for egress. Note however that frames from the same VC MUST NOT be reordered.
如果隧道协议提供了可以被设置为指定服务质量的字段，则入口路由器R1可以在确定该字段的值时考虑帧中继头的DE位。出口路由器然后可以考虑当排队2层PDU用于出口时该字段的值。但是请注意，来自同一VC的帧不得重新排序。
* C ( C/R ) Bit
* C（C/R）位
The ingress router, R1, SHOULD copy the C/R bit from the received Frame Relay PDU to the C bit of the control word. The egress router, R2, MUST copy the C bit into the output frame.
入口路由器R1应将接收到的帧中继PDU的C/R位复制到控制字的C位。出口路由器R2必须将C位复制到输出帧中。
Two encapsulations are supported for ATM transport: one for ATM Adaption Layer 5 (AAL5) and another for ATM cells.
ATM传输支持两种封装：一种用于ATM适配层5（AAL5），另一种用于ATM信元。
The AAL5 Common Part Convergence Sublayer - Service Data Unit (CPCS-SDU) encapsulation consists of the REQUIRED control word and the AAL5 CPCS-SDU. The ATM cell encapsulation consists of an OPTIONAL control word, a 4-byte ATM cell header, and the ATM cell payload.
AAL5公共部分聚合子层-服务数据单元（CPCS-SDU）封装由所需的控制字和AAL5 CPCS-SDU组成。ATM信元封装由可选控制字、4字节ATM信元报头和ATM信元有效负载组成。
In ATM AAL5 mode, the ingress router is required to reassemble AAL5 CPCS-SDUs from the incoming VC and transport each CPCS-SDU as a single packet. No AAL5 trailer is transported. The control word is REQUIRED; its use, however, is optional, although desirable. Use of the control word means that the ingress and egress LSRs follow the procedures below. If an ingress LSR chooses not to use the control word, it MUST set the flags in the control word to 0; if an egress LSR chooses to ignore the control word, it MUST set the ATM control bits to 0.
在ATM AAL5模式下，入口路由器需要从传入VC重新组装AAL5 CPCS SDU，并将每个CPCS-SDU作为单个数据包传输。未运输AAL5拖车。控制字是必需的；然而，它的使用是可选的，尽管是可取的。使用控制字意味着入口和出口LSR遵循以下程序。如果入口LSR选择不使用控制字，则必须将控制字中的标志设置为0；如果出口LSR选择忽略控制字，则必须将ATM控制位设置为0。
The EFCI (Explicit Forward Congestion Indication) and CLP (Cell Loss Priority) bits are carried across the network in the control word. The edge routers that implement this document MAY, when either adding or removing the encapsulation described herein, change the EFCI bit from 0 to 1 in order to reflect congestion in the network that is known to the edge routers, and the CLP bit from 0 to 1 to reflect marking from edge policing of the ATM Sustained Cell Rate. The EFCI and CLP bits MUST NOT be changed from 1 to 0.
EFCI（显式前向拥塞指示）和CLP（小区丢失优先级）位在控制字中通过网络传输。实现本文档的边缘路由器可在添加或移除本文所述封装时，将EFCI位从0更改为1以反映边缘路由器已知的网络拥塞，将CLP位从0更改为1以反映ATM持续信元速率的边缘监管标记。EFCI和CLP位不得从1更改为0。
The AAL5 CPCS-SDU is prepended by the following header:
AAL5 CPCS-SDU由以下标题组成：
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Rsvd |T|E|L|C| Length | Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ATM AAL5 CPCS-SDU |
| " |
| " |
| " |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Rsvd |T|E|L|C| Length | Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ATM AAL5 CPCS-SDU |
| " |
| " |
| " |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* T (transport type) bit
* T（传输型）位
Bit (T) of the control word indicates whether the packet contains an ATM cell or an AAL5 CPCS-SDU. If set, the packet contains an ATM cell, encapsulated according to the ATM cell mode section below; otherwise, it contains an AAL5 CPCS-SDU. The ability to transport an ATM cell in the AAL5 mode is intended to provide a means of enabling Operations and Management (OAM) functionality over the AAL5 VC.
控制字的位（T）指示数据包是包含ATM信元还是AAL5 CPCS-SDU。如果设置，则分组包含一个ATM信元，根据下面的ATM信元模式部分进行封装；否则，它包含一个AAL5 CPCS-SDU。在AAL5模式下传输ATM信元的能力旨在提供一种通过AAL5 VC启用操作和管理（OAM）功能的方法。
* E ( EFCI ) Bit
* E（EFCI）位
The ingress router, R1, SHOULD set this bit to 1 if the EFCI bit of the final cell of those that transported the AAL5 CPCS-SDU is set to 1, or if the EFCI bit of the single ATM cell to be transported in the packet is set to 1. Otherwise, this bit SHOULD be set to 0. The egress router, R2, SHOULD set the EFCI bit of all cells that transport the AAL5 CPCS-SDU to the value contained in this field.
如果传输AAL5 CPCS-SDU的最终信元的EFCI位设置为1，或者如果要在分组中传输的单个ATM信元的EFCI位设置为1，则入口路由器R1应将该位设置为1。否则，该位应设置为0。出口路由器R2应将传输AAL5 CPCS-SDU的所有单元的EFCI位设置为该字段中包含的值。
* L ( CLP ) Bit
* L（CLP）位
The ingress router, R1, SHOULD set this bit to 1 if the CLP bit of any of the ATM cells that transported the AAL5 CPCS-SDU is set to 1, or if the CLP bit of the single ATM cell to be transported in the packet is set to 1. Otherwise, this bit SHOULD be set to 0. The egress router, R2, SHOULD set the CLP bit of all cells that transport the AAL5 CPCS-SDU to the value contained in this field.
如果传输AAL5 CPCS-SDU的任何ATM信元的CLP位设置为1，或者如果要在数据包中传输的单个ATM信元的CLP位设置为1，则入口路由器R1应将该位设置为1。否则，该位应设置为0。出口路由器R2应将传输AAL5 CPCS-SDU的所有单元的CLP位设置为该字段中包含的值。
* C ( Command / Response Field ) Bit
* C（命令/响应字段）位
When FRF.8.1 Frame Relay / ATM PVC Service Interworking [FRF.8.1] traffic is being transported, the CPCS-UU Least Significant Bit (LSB) of the AAL5 CPCS-SDU may contain the Frame Relay C/R bit. The ingress router, R1, SHOULD copy this bit to the C bit of the control word. The egress router, R2, SHOULD copy the C bit to the CPCS-UU Least Significant Bit (LSB) of the AAL5 CPCS PDU.
当传输FRF.8.1帧中继/ATM PVC业务互通[FRF.8.1]业务时，AAL5 CPCS-SDU的CPCS-UU最低有效位（LSB）可能包含帧中继C/R位。入口路由器R1应将该位复制到控制字的C位。出口路由器R2应将C位复制到AAL5 CPCS PDU的CPCS-UU最低有效位（LSB）。
In this encapsulation mode, ATM cells are transported individually without a Segmentation and Reassembly (SAR) process. The ATM cell encapsulation consists of an OPTIONAL control word, and one or more ATM cells - each consisting of a 4-byte ATM cell header and the 48- byte ATM cell payload. This ATM cell header is defined in the FAST encapsulation [FAST] section 3.1.1, but without the trailer byte. The length of each frame, without the encapsulation headers, is a multiple of 52 bytes long. The maximum number of ATM cells that can be fitted in a frame, in this fashion, is limited only by the network MTU and by the ability of the egress router to process them. The ingress router MUST NOT send more cells than the egress router is willing to receive. The number of cells that the egress router is willing to receive may either be configured in the ingress router or may be signaled, for example, using the methods described in [RFC4906]. The number of cells encapsulated in a particular frame can be inferred by the frame length. The control word is OPTIONAL.
在这种封装模式下，ATM信元单独传输，无需分段和重组（SAR）过程。ATM信元封装由一个可选控制字和一个或多个ATM信元组成，每个信元由一个4字节的ATM信元头和48字节的ATM信元有效载荷组成。该ATM信元报头在快速封装[FAST]第3.1.1节中定义，但没有尾部字节。没有封装头的每个帧的长度是52字节长的倍数。以这种方式，可以安装在一个帧中的最大ATM信元数仅受网络MTU和出口路由器处理它们的能力的限制。入口路由器发送的小区数不得超过出口路由器愿意接收的小区数。出口路由器愿意接收的小区的数量可以在入口路由器中配置，或者可以例如使用[RFC4906]中描述的方法发信号。封装在特定帧中的单元数可以通过帧长度推断。控制字是可选的。
If the control word is used, then the flag bits in the control word are not used, and MUST be set to 0 when transmitting, and MUST be ignored upon receipt.
如果使用了控制字，则不使用控制字中的标志位，在传输时必须设置为0，并且在接收时必须忽略。
The EFCI and CLP bits are carried across the network in the ATM cell header. The edge routers that implement this document MAY, when either adding or removing the encapsulation described herein, change the EFCI bit from 0 to 1 in order to reflect congestion in the network that is known to the edge router, and the CLP bit from 0 to 1 to reflect marking from edge policing of the ATM Sustained Cell Rate. The EFCI and CLP bits SHOULD NOT be changed from 1 to 0.
EFCI和CLP位在ATM信元报头中通过网络传输。实现本文档的边缘路由器可在添加或移除本文所述的封装时，将EFCI位从0更改为1以反映边缘路由器已知的网络拥塞，将CLP位从0更改为1以反映ATM持续信元速率的边缘监管标记。EFCI和CLP位不应从1更改为0。
This diagram illustrates an encapsulation of two ATM cells:
此图显示了两个ATM信元的封装：
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Control word ( Optional ) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| VPI | VCI | PTI |C|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ATM Payload ( 48 bytes ) |
| " |
| " |
| " |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| VPI | VCI | PTI |C|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ATM Payload ( 48 bytes ) |
| " |
| " |
| " |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Control word ( Optional ) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| VPI | VCI | PTI |C|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ATM Payload ( 48 bytes ) |
| " |
| " |
| " |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| VPI | VCI | PTI |C|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ATM Payload ( 48 bytes ) |
| " |
| " |
| " |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* VPI (Virtual Path Identifier)
* 虚拟路径标识符（VPI）
The ingress router MUST copy the VPI field from the incoming cell into this field. For particular emulated VCs, the egress router MAY generate a new VPI and ignore the VPI contained in this field.
入口路由器必须将VPI字段从传入单元复制到此字段中。对于特定的仿真VCs，出口路由器可以生成新的VPI并忽略该字段中包含的VPI。
* VCI (Virtual Circuit Identifier)
* 虚拟电路标识符（VCI）
The ingress router MUST copy the VCI field from the incoming ATM cell header into this field. For particular emulated VCs, the egress router MAY generate a new VCI.
入口路由器必须将VCI字段从传入ATM信元报头复制到此字段中。对于特定的仿真vc，出口路由器可以生成新的VCI。
* PTI (Payload Type Identifier) & CLP ( C bit )
* PTI（有效负载类型标识符）和CLP（C位）
The PTI and CLP fields are the PTI and CLP fields of the incoming ATM cells. The cell headers of the cells within the packet are the ATM headers (without HEC) of the incoming cell.
PTI和CLP字段是传入ATM信元的PTI和CLP字段。包内信元的信元报头是传入信元的ATM报头（不含HEC）。
OAM cells MAY be transported on the VC LSP. An egress router that does not support transport of OAM cells MUST discard frames that contain an ATM cell with the high-order bit of the PTI field set to 1. A router that supports transport of OAM cells MUST follow the procedures outlined in [FAST] section 8 for mode 0 only, in addition to the applicable procedures specified in [RFC4906].
OAM单元可以在VC LSP上传输。不支持OAM信元传输的出口路由器必须丢弃包含PTI字段高阶位设置为1的ATM信元的帧。除[RFC4906]中规定的适用程序外，支持OAM单元传输的路由器必须遵循[FAST]第8节中针对模式0概述的程序。
The ingress router MAY consider the CLP bit when determining the value to be placed in the Quality of Service fields (e.g., the EXP fields of the MPLS label stack) of the encapsulating protocol. This gives the network visibility of the CLP bit. Note however that cells from the same VC MUST NOT be reordered.
入口路由器可以在确定要放置在封装协议的服务质量字段（例如，MPLS标签堆栈的EXP字段）中的值时考虑CLP比特。这提供了CLP位的网络可见性。但是请注意，来自同一VC的单元格不得重新排序。
For an Ethernet 802.1q VLAN, the entire Ethernet frame without the preamble or FCS is transported as a single packet. The control word is OPTIONAL. If the control word is used, then the flag bits in the control word are not used, and MUST be set to 0 when transmitting, and MUST be ignored upon receipt. The 4-byte VLAN tag is transported as is, and MAY be overwritten by the egress router.
对于以太网802.1q VLAN，不带前导码或FCS的整个以太网帧作为单个数据包传输。控制字是可选的。如果使用了控制字，则不使用控制字中的标志位，在传输时必须设置为0，并且在接收时必须忽略。4字节VLAN标记按原样传输，并可能被出口路由器覆盖。
The ingress router MAY consider the user priority field [IEEE802.3ac] of the VLAN tag header when determining the value to be placed in the Quality of Service field of the encapsulating protocol (e.g., the EXP fields of the MPLS label stack). In a similar way, the egress router MAY consider the Quality of Service field of the encapsulating protocol when queuing the packet for egress. Ethernet packets containing hardware-level Cyclic Redundancy Check (CRC) errors, framing errors, or runt packets MUST be discarded on input.
入口路由器可以在确定要放置在封装协议（例如，MPLS标签堆栈的EXP字段）中的值时考虑VLAN标签头的用户优先级字段[IEEE802.3ac ]。以类似的方式，出口路由器可以考虑在封装该数据包时对封装协议的服务质量字段。包含硬件级循环冗余校验（CRC）错误、帧错误或runt数据包的以太网数据包必须在输入时丢弃。
For simple Ethernet port to port transport, the entire Ethernet frame without the preamble or FCS is transported as a single packet. The control word is OPTIONAL. If the control word is used, then the flag bits in the control word are not used, and MUST be set to 0 when transmitting, and MUST be ignored upon receipt. As in the Ethernet
对于简单的以太网端口到端口传输，不带前导码或FCS的整个以太网帧作为单个数据包传输。控制字是可选的。如果使用了控制字，则不使用控制字中的标志位，在传输时必须设置为0，并且在接收时必须忽略。就像在以太网中一样
VLAN case, Ethernet packets with hardware-level CRC errors, framing errors, and runt packets MUST be discarded on input.
VLAN情况下，具有硬件级CRC错误、帧错误和runt数据包的以太网数据包必须在输入时丢弃。
HDLC mode provides port to port transport of HDLC-encapsulated traffic. The HDLC PDU is transported in its entirety, including the HDLC address, control, and protocol fields, but excluding HDLC flags and the FCS. Bit/byte stuffing is undone. The control word is OPTIONAL. If the control word is used, then the flag bits in the control word are not used, and MUST be set to 0 when transmitting, and MUST be ignored upon receipt.
HDLC模式提供HDLC封装流量的端口到端口传输。HDLC PDU整体传输，包括HDLC地址、控制和协议字段，但不包括HDLC标志和FCS。位/字节填充被撤消。控制字是可选的。如果使用了控制字，则不使用控制字中的标志位，在传输时必须设置为0，并且在接收时必须忽略。
The HDLC mode is suitable for port to port transport of Frame Relay User-Network Interface (UNI) or Network-Network Interface (NNI) traffic. It must be noted, however, that this mode is transparent to the FECN, BECN, and DE bits.
HDLC模式适用于帧中继用户网络接口（UNI）或网络网络接口（NNI）流量的端口到端口传输。然而，必须注意，该模式对FECN、BECN和DE比特是透明的。
PPP mode provides point to point transport of PPP-encapsulated traffic, as specified in [RFC1661]. The PPP PDU is transported in its entirety, including the protocol field (whether compressed using PFC or not), but excluding any media-specific framing information, such as HDLC address and control fields or FCS. Since media-specific framing is not carried, the following options will not operate correctly if the PPP peers attempt to negotiate them:
PPP模式提供PPP封装流量的点对点传输，如[RFC1661]中所述。PPP PDU整体传输，包括协议字段（无论是否使用PFC压缩），但不包括任何特定于媒体的帧信息，如HDLC地址和控制字段或FCS。由于未进行媒体特定帧，如果PPP对等方试图协商，则以下选项将无法正常运行：
- Frame Check Sequence (FCS) Alternatives - Address-and-Control-Field-Compression (ACFC) - Asynchronous-Control-Character-Map (ACCM)
- 帧检查序列（FCS）备选方案-地址和控制字段压缩（ACFC）-异步控制字符映射（ACCM）
Note also that VC LSP Interface MTU negotiation as specified in [RFC4906] is not affected by PPP Maximum Receive Unit (MRU) advertisement. Thus, if a PPP peer sends a PDU with a length in excess of that negotiated for the VC LSP, that PDU will be discarded by the ingress router.
还要注意，[RFC4906]中规定的VC LSP接口MTU协商不受PPP最大接收单元（MRU）公告的影响。因此，如果PPP对等方发送的PDU长度超过为VC LSP协商的长度，则该PDU将被入口路由器丢弃。
The control word is OPTIONAL. If the control word is used, then the flag bits in the control word are not used, and MUST be set to 0 when transmitting, and MUST be ignored upon receipt.
控制字是可选的。如果使用了控制字，则不使用控制字中的标志位，在传输时必须设置为0，并且在接收时必须忽略。
To use an MPLS label as the demultiplexer field, a 32-bit label stack entry [RFC3032] is simply prepended to the emulated VC encapsulation, and hence will appear as the bottom label of an MPLS label stack. This label may be called the "VC label". The particular emulated VC
要使用MPLS标签作为解复用器字段，只需将32位标签堆栈条目[RFC3032]添加到模拟VC封装之前，因此将显示为MPLS标签堆栈的底部标签。该标签可称为“VC标签”。特定的模拟VC
identified by a particular label value must be agreed by the ingress and egress LSRs, either by signaling (e.g., via the methods of [RFC4906]) or by configuration. Other fields of the label stack entry are set as follows.
由特定标签值标识的标识必须由入口和出口LSR通过信令（例如，通过[RFC4906]的方法）或配置达成一致。标签堆栈项的其他字段设置如下。
If it is desired to carry Quality of Service information, the Quality of Service information SHOULD be represented in the EXP field of the VC label. If more than one MPLS label is imposed by the ingress LSR, the EXP field of any labels higher in the stack SHOULD also carry the same value.
如果需要携带服务质量信息，服务质量信息应在VC标签的EXP字段中表示。如果入口LSR施加了多个MPLS标签，则堆栈中任何较高标签的EXP字段也应具有相同的值。
The ingress LSR, R1, MUST set the S bit of the VC label to a value of 1 to denote that the VC label is at the bottom of the stack.
入口LSR R1必须将VC标签的S位设置为1，以表示VC标签位于堆栈底部。
The ingress LSR, R1, SHOULD set the TTL field of the VC label to a value of 2.
入口LSR R1应将VC标签的TTL字段设置为2。
This document specifies only encapsulations, and not the protocols, used to carry the encapsulated packets across the network. Each such protocol may have its own set of security issues, but those issues are not affected by the encapsulations specified herein. More detailed security considerations are also described in Section 8 of [RFC4447].
本文档仅指定用于在网络上传输封装数据包的封装，而不是协议。每个这样的协议可能有其自己的一组安全问题，但是这些问题不受本文指定的封装的影响。[RFC4447]的第8节还描述了更详细的安全注意事项。
[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。
[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。
[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。
[RFC4842] Malis, A., Pate, P., Cohen, R., Ed., and D. Zelig, "Synchronous Optical Network/Synchronous Digital Hierarchy (SONET/SDH) Circuit Emulation over Packet (CEP)", RFC 4842, April 2007.
[RFC4842]Malis，A.，Pate，P.，Cohen，R.，Ed.，和D.Zelig，“同步光网络/同步数字体系（SONET/SDH）分组电路仿真（CEP）”，RFC 4842，2007年4月。
[RFC4553] Vainshtein, A., Ed., and YJ. Stein, Ed., "Structure-Agnostic Time Division Multiplexing (TDM) over Packet (SAToP)", RFC 4553, June 2006.
[RFC4553]Vainstein，A.，Ed.，和YJ。Stein，Ed.“数据包上的结构不可知时分复用（TDM）（SAToP）”，RFC4553，2006年6月。
[RFC4619] Martini, L., Ed., Kawa, C., Ed., and A. Malis, Ed., "Encapsulation Methods for Transport of Frame Relay over Multiprotocol Label Switching (MPLS) Networks", RFC 4619, September 2006.
[RFC4619]Martini，L.，Ed.，Kawa，C.，Ed.，和A.Malis，Ed.，“多协议标签交换（MPLS）网络上帧中继传输的封装方法”，RFC 4619，2006年9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。
[RFC4618] Martini, L., Rosen, E., Heron, G., and A. Malis, "Encapsulation Methods for Transport of PPP/High-Level Data Link Control (HDLC) over MPLS Networks", RFC 4618, September 2006.
[RFC4618]Martini，L.，Rosen，E.，Heron，G.，和A.Malis，“通过MPLS网络传输PPP/高级数据链路控制（HDLC）的封装方法”，RFC 4618，2006年9月。
[RFC4448] Martini, L., Ed., Rosen, E., El-Aawar, N., and G. Heron, "Encapsulation Methods for Transport of Ethernet over MPLS Networks", RFC 4448, April 2006.
[RFC4448]Martini，L.，Ed.，Rosen，E.，El Aawar，N.，和G.Heron，“通过MPLS网络传输以太网的封装方法”，RFC 4448，2006年4月。
[RFC4906] Martini, L., Ed., Rosen, E., Ed., and N. El-Aawar, Ed., "Transport of Layer 2 Frames Over MPLS", RFC 4906, June 2007.
[RFC4906]Martini，L.，Ed.，Rosen，E.，Ed.，和N.El Aawar，Ed.，“MPLS上的第2层帧传输”，RFC 4906，2007年6月。
[RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y., Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack Encoding", RFC 3032, January 2001.
[RFC3032]Rosen，E.，Tappan，D.，Fedorkow，G.，Rekhter，Y.，Farinaci，D.，Li，T.，和A.Conta，“MPLS标签堆栈编码”，RFC 3032，2001年1月。
[FRF.8.1] Frame Relay Forum, "Frame Relay / ATM PVC Service Interworking Implementation Agreement", February 2000.
[FRF.8.1]帧中继论坛，“帧中继/ATM PVC业务互通实施协议”，2000年2月。
[FAST] ATM Forum, "Frame Based ATM over SONET/SDH Transport (FAST)", af-fbatm-0151.000, July 2000.
[FAST]ATM论坛，“基于帧的SONET/SDH传输ATM（FAST）”，af-fbatm-0151.000，2000年7月。
[IEEE802.3ac] IEEE 802.3ac-1998, "Information technology - Telecommunications and information exchange between systems - Local and metropolitan area networks - Specific requirements Part 3: Carrier sense multiple access with collision detection (CSMA/CD) frame extensions for Virtual Bridged Local Area Networks (VLAN) tagging on 802.3 networks".
[IEEE802.3ac]IEEE 802.3ac-1998，“信息技术-系统间电信和信息交换-局域网和城域网-特定要求第3部分：802.3网络上虚拟桥接局域网（VLAN）标记的带冲突检测的载波侦听多址（CSMA/CD）帧扩展”。
[RFC1661] Simpson, W., Ed., "The Point-to-Point Protocol (PPP)", STD 51, RFC 1661, July 1994.
[RFC1661]辛普森，W.，编辑，“点对点协议（PPP）”，标准51，RFC1661，1994年7月。
Giles Heron Tellabs Abbey Place 24-28 Easton Street High Wycombe Bucks HP11 1NT UK EMail: giles.heron@tellabs.com
Giles Heron Tellabs Abbey Place 24-28 Easton Street High Wycombe Bucks HP11 1NT英国电子邮件：Giles。heron@tellabs.com
Dimitri Stratton Vlachos Mazu Networks, Inc. 125 Cambridgepark Drive Cambridge, MA 02140 EMail: d@mazunetworks.com
Dimitri Stratton Vlachos Mazu Networks，Inc.马萨诸塞州剑桥市剑桥公园大道125号邮编：02140电子邮件：d@mazunetworks.com
Dan Tappan Cisco Systems, Inc. 1414 Massachusetts Avenue Boxborough, MA 01719 EMail: tappan@cisco.com
Dan Tappan Cisco Systems，Inc.马萨诸塞州伯斯堡马萨诸塞大道1414号邮编01719电子邮件：tappan@cisco.com
Jayakumar Jayakumar Cisco Systems Inc. 225, E.Tasman, MS-SJ3/3, San Jose, CA 95134 EMail: jjayakum@cisco.com
Jayakumar Jayakumar Cisco Systems Inc.225，E.Tasman，MS-SJ3/3，加利福尼亚州圣何塞95134电子邮件：jjayakum@cisco.com
Alex Hamilton Cisco Systems Inc. 285 W. Tasman, MS-SJCI/3/4, San Jose, CA 95134 EMail: tahamilt@cisco.com
Alex Hamilton Cisco Systems Inc.285 W.Tasman，MS-SJCI/3/4，加利福尼亚州圣何塞95134电子邮件：tahamilt@cisco.com
Steve Vogelsang Laurel Networks, Inc. Omega Corporate Center 1300 Omega Drive Pittsburgh, PA 15205 EMail: sjv@laurelnetworks.com
Steve Vogelsang Laurel Networks，Inc.宾夕法尼亚州匹兹堡欧米茄大道1300号欧米茄企业中心15205电子邮件：sjv@laurelnetworks.com
John Shirron Laurel Networks, Inc. Omega Corporate Center 1300 Omega Drive Pittsburgh, PA 15205 EMail: jshirron@laurelnetworks.com
John Shirron Laurel Networks，Inc.宾夕法尼亚州匹兹堡欧米茄大道1300号欧米茄企业中心15205电子邮件：jshirron@laurelnetworks.com
Toby Smith Network Appliance, Inc. 800 Cranberry Woods Drive Suite 300 Cranberry Township, PA 16066 EMail: tob@netapp.com
Toby Smith Network Appliance，Inc.宾夕法尼亚州蔓越莓镇800蔓越莓树林大道300号套房16066电子邮件：tob@netapp.com
Andrew G. Malis Tellabs 90 Rio Robles Dr. San Jose, CA 95134 EMail: Andy.Malis@tellabs.com
Andrew G.Malis Tellabs 90 Rio Robles博士加利福尼亚州圣何塞95134电子邮件：Andy。Malis@tellabs.com
Vinai Sirkay Redback Networks 300 Holger Way San Jose, CA 95134 EMail: vsirkay@redback.com
Vinai Sirkay Redback Networks加利福尼亚州圣何塞霍尔格路300号95134电子邮件：vsirkay@redback.com
Vasile Radoaca Nortel Networks 600 Technology Park Billerica MA 01821 EMail: vasile@nortelnetworks.com
Vasile Radoaca Nortel Networks 600科技园Billerica MA 01821电子邮件：vasile@nortelnetworks.com
Chris Liljenstolpe Alcatel 11600 Sallie Mae Dr. 9th Floor Reston, VA 20193 EMail: chris.liljenstolpe@alcatel.com
Chris Liljenstolpe Alcatel 11600 Sallie Mae博士，弗吉尼亚州雷斯顿市9楼，邮编20193电子邮件：Chris。liljenstolpe@alcatel.com
Dave Cooper Global Crossing 960 Hamlin Court Sunnyvale, CA 94089 EMail: dcooper@gblx.net
Dave Cooper Global Crossing 960加利福尼亚州桑尼维尔哈姆林法院94089电子邮件：dcooper@gblx.net
Kireeti Kompella Juniper Networks 1194 N. Mathilda Ave Sunnyvale, CA 94089 EMail: kireeti@juniper.net
Kireeti Kompella Juniper Networks 1194 N.Mathilda Ave Sunnyvale，CA 94089电子邮件：kireeti@juniper.net
Authors' Addresses
作者地址
Luca Martini Cisco Systems, Inc. 9155 East Nichols Avenue, Suite 400 Englewood, CO 80112 EMail: lmartini@cisco.com
Luca Martini Cisco Systems，Inc.地址：科罗拉多州恩格尔伍德东尼科尔斯大道9155号400室，邮编：80112电子邮件：lmartini@cisco.com
Nasser El-Aawar Level 3 Communications, LLC. 1025 Eldorado Blvd. Broomfield, CO 80021 EMail: nna@level3.net
Nasser El Aawar三级通信有限责任公司，埃尔多拉多大道1025号。美国科罗拉多州布鲁姆菲尔德80021电子邮件：nna@level3.net
Eric Rosen Cisco Systems, Inc. 1414 Massachusetts Avenue Boxborough, MA 01719 EMail: erosen@cisco.com
Eric Rosen Cisco Systems，Inc.马萨诸塞州伯斯堡马萨诸塞大道1414号邮编01719电子邮件：erosen@cisco.com
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