Network Working Group B. Berry
Request for Comments: 4938 H. Holgate
Category: Informational Cisco Systems,Inc.
June 2007
Network Working Group B. Berry
Request for Comments: 4938 H. Holgate
Category: Informational Cisco Systems,Inc.
June 2007
PPP Over Ethernet (PPPoE) Extensions for Credit Flow and Link Metrics
用于信用流量和链路指标的以太网PPP（PPPoE）扩展
Status of This Memo
关于下段备忘
This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited.
本备忘录为互联网社区提供信息。它没有规定任何类型的互联网标准。本备忘录的分发不受限制。
Copyright Notice
版权公告
Copyright (C) The IETF Trust (2007).
版权所有（C）IETF信托基金（2007年）。
IESG Note
IESG注释
The PPP Extensions Working Group (PPPEXT) has reservations about the desirability of the feature described in this document. In particular, it solves a general problem at an inappropriate layer and it may have unpredictable interactions with higher and lower level protocols. The techniques described in this document are intended for use with a particular deployment technique that uses a PPP termination separated from a radio termination by an Ethernet, and that has radio-side flow control for a slower PPP-only link to remote nodes. Implementors are better advised to avoid split termination with inter-media protocol translation, and use standard Internet Protocol routing instead.
PPP扩展工作组（PPPEXT）对本文件所述功能的可取性持保留意见。特别是，它在一个不合适的层上解决了一个一般问题，并且它可能与更高和更低级别的协议进行不可预测的交互。本文档中描述的技术旨在与特定部署技术一起使用，该部署技术使用通过以太网与无线电终端分离的PPP终端，并且具有用于到远程节点的仅较慢PPP链路的无线电侧流控制。最好建议实施者避免使用媒体间协议转换进行拆分终止，而是使用标准的Internet协议路由。
Abstract
摘要
This document extends the Point-to-Point over Ethernet (PPPoE) Protocol with a credit-based flow control mechanism and Link Quality Metric report. This optional extension should improve the performance of PPPoE over media with variable bandwidth and limited buffering, such as mobile radio links.
本文档使用基于信用的流量控制机制和链路质量度量报告扩展了以太网点对点（PPPoE）协议。此可选扩展应能提高PPPoE在具有可变带宽和有限缓冲的介质（如移动无线电链路）上的性能。
Table of Contents
目录
1. Introduction ....................................................2
2. Payload .........................................................3
3. Overview of Protocol Extensions .................................3
4. Discovery Stage .................................................3
4.1. PPPoE Active Discovery Request (PADR) ......................4
4.2. PPPoE Active Discovery Session-confirmation (PADS) .........4
4.3. PPPoE Active Discovery Session-Grant (PADG) ................5
4.4. PPPoE Active Discovery Session-Credit Response (PADC) ......5
4.5. PPPoE Active Discovery Quality (PADQ) ......................6
5. PPP Session Stage ...............................................7
6. Credit Flow Considerations ......................................7
7. PADG and PADC Retransmission ....................................8
8. Other Considerations ............................................9
9. IANA Considerations .............................................9
10. Security Considerations ........................................9
Appendix A: Tag Values.............................................10
Appendix B: Example Message Formats................................11
Acknowledgements...................................................15
Normative References...............................................15
1. Introduction ....................................................2
2. Payload .........................................................3
3. Overview of Protocol Extensions .................................3
4. Discovery Stage .................................................3
4.1. PPPoE Active Discovery Request (PADR) ......................4
4.2. PPPoE Active Discovery Session-confirmation (PADS) .........4
4.3. PPPoE Active Discovery Session-Grant (PADG) ................5
4.4. PPPoE Active Discovery Session-Credit Response (PADC) ......5
4.5. PPPoE Active Discovery Quality (PADQ) ......................6
5. PPP Session Stage ...............................................7
6. Credit Flow Considerations ......................................7
7. PADG and PADC Retransmission ....................................8
8. Other Considerations ............................................9
9. IANA Considerations .............................................9
10. Security Considerations ........................................9
Appendix A: Tag Values.............................................10
Appendix B: Example Message Formats................................11
Acknowledgements...................................................15
Normative References...............................................15
PPP over Ethernet (PPPoE) [2] is a protocol for establishing and encapsulating sessions between hosts and traffic aggregators (Access Concentrators) for PPP [1] transport over real or emulated Ethernet. PPPoE works well when both session endpoints have similar bandwidth, forwarding, and buffering capabilities that do not vary over time. However, it is insufficient for applications with variable bandwidth and limited buffering (for example, mobile radio links). This document addresses this problem by suggesting an extension to PPPoE to support credit-based session flow control and session-based link metric exchanges.
以太网PPP（PPPoE）[2]是一种协议，用于在主机和流量聚合器（访问集中器）之间建立和封装会话，以便通过真实或模拟以太网进行PPP[1]传输。当两个会话端点具有相似的带宽、转发和缓冲能力且不随时间变化时，PPPoE工作良好。但是，对于带宽可变且缓冲有限的应用程序（例如，移动无线电链路），它是不够的。本文档通过建议PPPoE的扩展来解决此问题，以支持基于信用的会话流控制和基于会话的链路度量交换。
The diagram below illustrates the problem that this extension is intended to solve, for the case of a radio link. Here PPPoE sessions are used between access concentrators (routers) and radio transmission systems that are shown as radio neighbors. Each radio transmission system establishes point-to-point Radio Link Protocol (RLP) sessions with its neighbors and establishes a corresponding PPPoE session for each neighbor with the transmission system's associated access concentrator (router). The radio logically associates the PPPoE session with the corresponding RLP session.
下图说明了在无线链路的情况下，此扩展旨在解决的问题。这里，PPPoE会话用于接入集中器（路由器）和显示为无线电邻居的无线电传输系统之间。每个无线传输系统与其邻居建立点对点无线链路协议（RLP）会话，并与传输系统的相关接入集中器（路由器）为每个邻居建立相应的PPPoE会话。无线电从逻辑上将PPPoE会话与相应的RLP会话相关联。
+--------+ +-------+ +-------+ +--------+
| Access | | Host | | Host | | Access |
| Conc. |=======| Radio |~~~~~~~| Radio |=======| Conc. |
+--------+ +-------+ +-------+ +--------+
| | | | | |
|-PPPoE-| |--RLP--| |-PPPoE-|
| |
|-------------PPP Session---------------|
+--------+ +-------+ +-------+ +--------+
| Access | | Host | | Host | | Access |
| Conc. |=======| Radio |~~~~~~~| Radio |=======| Conc. |
+--------+ +-------+ +-------+ +--------+
| | | | | |
|-PPPoE-| |--RLP--| |-PPPoE-|
| |
|-------------PPP Session---------------|
Figure 1. PPPoE Network
图1。PPPoE网络
The capabilities of the RF links between RLP neighbors may vary over time due to mobility and environmental conditions. In many instances, the Host Radio has limited buffering capability to handle capacity changes in the RLP sessions. To limit buffering in the Host Radio, the PPPoE credit flow control mechanism provides dynamic buffering feedback to the access concentrator.
由于移动性和环境条件，RLP邻居之间的RF链路的能力可能随时间而变化。在许多情况下，主机无线电具有有限的缓冲能力来处理RLP会话中的容量变化。为了限制主机无线电中的缓冲，PPPoE信用流控制机制向接入集中器提供动态缓冲反馈。
In the diagram above, from the access concentrator's perspective, each PPPoE session between it and the Host Radio represent a connection to a remote routable peer. For efficient routing, the local Host Radio uses the link metric mechanism to dynamically update the access concentrator route cost of the associated link.
在上图中，从访问集中器的角度来看，它和主机无线电之间的每个PPPoE会话表示到远程可路由对等方的连接。为了高效路由，本地主机无线电使用链路度量机制来动态更新相关链路的接入集中器路由成本。
While the example shows an RF-based application, the extensions are applicable to other media.
虽然示例显示了基于射频的应用程序，但这些扩展适用于其他媒体。
The Ethernet payload version field retains its value of 0x01. The extensions for credit flow control and link quality metrics are optional and backward compatible.
以太网有效负载版本字段保留其值0x01。信贷流控制和链接质量度量的扩展是可选的，并且向后兼容。
PPPoE has two distinct stages. There is a Discovery Stage and a PPP Session Stage. During the Discovery Stage, the Host can optionally request a flow controlled PPP Session Stage. Once the Access Concentrator acknowledges the Host flow control request, all PPP Session Stage traffic must be flow controlled.
PPPoE有两个不同的阶段。有发现阶段和PPP会话阶段。在发现阶段，主机可以选择请求流控制的PPP会话阶段。一旦接入集中器确认主机流量控制请求，所有PPP会话阶段流量都必须进行流量控制。
The packet exchange of the Discovery Stage is unchanged by this specification. The specifications of the Session Request (PADR) and the Session Confirmation (PADS) packets are extended to include the optional Credit Tag Type-Length-Value (TLV).
发现阶段的数据包交换不受本规范的影响。会话请求（PADR）和会话确认（PADS）数据包的规范被扩展，以包括可选的信用标签类型长度值（TLV）。
In addition, the optional Credit Grant (PADG) packet, the Credit Response (PADC) packet, and the Link Quality Metric (PADQ) packets are introduced.
此外，还引入了可选信用授予（PADG）包、信用响应（PADC）包和链路质量度量（PADQ）包。
The PADR packet is extended to optionally contain a single Credit Tag TLV, indicating that the Host requests credit flow control for this session. The Credit Tag contains the Forward Credit Notification (FCN) and the Backward Credit Notification (BCN) to be applied to the PPP Session Stage. The FCN provides the initial credits granted to the Access Concentrator by the Host. The BCN value is set to 0.
PADR数据包被扩展为可选地包含单个信用标签TLV，表示主机请求此会话的信用流控制。信用标签包含要应用于PPP会话阶段的前向信用通知（FCN）和后向信用通知（BCN）。FCN提供主机授予访问集中器的初始信用。BCN值设置为0。
An example packet is shown in Appendix B.
附录B中显示了一个示例数据包。
The PADS packet is extended to optionally contain a single Credit Tag TLV, indicating the Forward Credit Notification (FCN) and the Backward Credit Notification (BCN) of the PPP Session Stage.
PADS分组被扩展以可选地包含单个信用标签TLV，指示PPP会话阶段的前向信用通知（FCN）和后向信用通知（BCN）。
If the PADR contained a Credit Tag, then the Access Concentrator PADS packet indicates support for credit flow control by including a Credit Tag. The PADS Credit Tag FCN represents the number of credits being initially granted to the Host. The Credit Tag BCN is an echo of the number of credits that the Host had granted to the Access Concentrator in the previous PADR packet.
如果PADR包含信用标签，那么接入集中器PADS分组通过包括信用标签来指示对信用流控制的支持。PADS信用标签FCN表示最初授予主机的信用数。信用标签BCN是主机在前一个PADR数据包中授予访问集中器的信用数的回音。
Exchange of the Credit Tag TLV in the PADR and PADS indicates that credit flow control is supported by both the Access Concentrator and the Host for the designated PPP Session Stage. This is binding and must be followed for the entire duration of the PPP Session Stage. A session's credit binding must be established prior to any other credit indications can be exchanged.
PADR和PADS中信用标签TLV的交换表明，对于指定的PPP会话阶段，访问集中器和主机都支持信用流控制。这是有约束力的，必须在PPP会话阶段的整个过程中遵守。在交换任何其他信用指示之前，必须先建立会话的信用约束。
The Access Concentrator PADS should only carry the Credit Tag in response to a Host PADR with Credits. If the Access Concentrator does not support credit flow, it should not include the Credit Tag in its PADS response. The Host must terminate a credit-based session that cannot be supported by the Access Concentrator. Credit Tags transmitted outside an established credit based session must be ignored.
接入集中器PAD应仅携带信用标签，以响应具有信用的主机PADR。如果访问集中器不支持信用流，则不应在其PADS响应中包含信用标签。主机必须终止访问集中器不支持的基于信用的会话。必须忽略在已建立的基于信用的会话之外传输的信用标签。
An example packet is shown in Appendix B.
附录B中显示了一个示例数据包。
The PPPoE Active Discovery Session-Grant (PADG) is a new packet defined in this specification. An Access Concentrator or Host MAY send a PADG at any time after the PADR/PADS exchange to grant incremental flow control credits. The CODE field is set to 0x0A and the SESSION_ID must be set to the unique value generated for this PPPoE Session.
PPPoE主动发现会话授权（PADG）是本规范中定义的新数据包。接入集中器或主机可在PADR/PADS交换后的任何时间发送PADG，以授予增量流量控制信用。代码字段设置为0x0A，会话ID必须设置为此PPPoE会话生成的唯一值。
The peer may then transmit data until the credits are exhausted.
对等方随后可以传输数据，直到信用耗尽。
When the peer receives a PADG packet, it adds the incremental credits to its working credit count and responds with a PPPoE Active Discovery Session-Credit (PADC) packet indicating the accumulated credits.
当对等方接收到PADG数据包时，它将增量信用添加到其工作信用计数中，并使用指示累积信用的PPPoE主动发现会话信用（PADC）数据包进行响应。
The PADG packet must contain a single Credit Tag TLV, indicating the Forward Credit Notification (FCN) and the Backward Credit Notification (BCN) of the PPP Session.
PADG数据包必须包含一个信用标签TLV，指示PPP会话的前向信用通知（FCN）和后向信用通知（BCN）。
The Credit Tag FCN indicates the number of incremental credits being granted to the peer by the node. A value between 1 and 0xffff represents an incremental credit grant. The peer must add these credits to its accumulated transmit credit count. A value of 0x0000 represents a NULL grant, meaning that there are no additional credits being granted.
信用标签FCN表示节点授予对等方的增量信用的数量。介于1和0xffff之间的值表示增量信用授予。对等方必须将这些信用添加到其累积的传输信用计数中。0x0000的值表示授予为空，这意味着不授予额外的学分。
The Credit Tag BCN indicates the remaining absolute credits that have been granted by the peer to the node.
信用标签BCN表示对等方已向节点授予的剩余绝对信用。
Once a credit has been granted, it must be honored. The largest number of outstanding credits at any time is 0xffff.
信用一旦被授予，就必须兑现。任何时候未偿还信用的最大数量为0xffff。
The PADG packet must contain a single Sequence Number Tag TLV. This tag is used to carry a unique 16-bit sequence number to uniquely identify each request. The sequence number should be initialized to zero and incremented by one for each new PADG. For retransmitted PADGs, the same sequence number that was used in the previous packet transmission is repeated.
PADG数据包必须包含一个序列号标签TLV。此标记用于携带唯一的16位序列号，以唯一标识每个请求。序列号应初始化为零，并为每个新PADG增加1。对于重新传输的PADG，重复先前数据包传输中使用的相同序列号。
An example packet is shown in Appendix B.
附录B中显示了一个示例数据包。
The PPPoE Active Discovery Session-Credit Response (PADC) is a new packet defined in this specification. An Access Concentrator or Host must send a PADC in response to a PADG. The CODE field is set to
PPPoE主动发现会话信用响应（PADC）是本规范中定义的新数据包。访问集中器或主机必须发送PADC以响应PADG。代码字段设置为
0x0B, and the SESSION_ID must be set to the unique value generated for this PPPoE session.
0x0B，并且会话ID必须设置为此PPPoE会话生成的唯一值。
The PADC packet must contain a single Credit Tag TLV, indicating the Forward Credit Notification (FCN) and the Backward Credit Notification (BCN) of the PPPoE session, and any number of other Tag types.
PADC数据包必须包含单个信用标签TLV，指示PPPoE会话的前向信用通知（FCN）和后向信用通知（BCN），以及任何数量的其他标签类型。
The Credit Tag FCN represents the absolute credits remaining that have been granted to the peer by the node. The Credit Tag BCN represents the remaining absolute credits that have been granted to the node from the peer.
信用标签FCN表示节点已授予对等方的绝对剩余信用。信用标签BCN表示已从对等方授予节点的剩余绝对信用。
The PADC packet must contain a single Sequence Number Tag. The sequence number must be the sequence number associated with the PADG.
PADC数据包必须包含一个序列号标签。序列号必须是与PADG关联的序列号。
An example packet is shown in Appendix B.
附录B中显示了一个示例数据包。
The PPPoE Active Discovery Quality (PADQ) is a new packet defined in this specification. An Access Concentrator or Host may send an optional PADQ at any time to query or report link quality metrics.
PPPoE主动发现质量（PADQ）是本规范中定义的新数据包。访问集中器或主机可随时发送可选PADQ以查询或报告链路质量指标。
When transmitting PPP [1] streams over wireless links through radio modems, the quality of the RF link directly affects the throughput. The PPPoE Active Discovery Quality (PADQ) packet can be used by the radio modem to report RF link metrics. The CODE field is set to 0x0C, and the SESSION_ID must be set to the unique value generated for this PPPoE session.
当通过无线调制解调器通过无线链路传输PPP[1]流时，RF链路的质量直接影响吞吐量。无线调制解调器可以使用PPPoE主动发现质量（PADQ）数据包来报告射频链路指标。代码字段设置为0x0C，会话ID必须设置为此PPPoE会话生成的唯一值。
The PADQ must carry a single Metric Tag TYPE, which contains the following fields:
PADQ必须携带一个公制标记类型，该类型包含以下字段：
Receive only - a bit that indicates whether the link is bi-directional or receive only. A value of -1- indicates that the link is receive-only.
仅接收-指示链路是双向的还是仅接收的位。值-1-表示链接仅用于接收。
Maximum data rate - the maximum theoretical data rate, in kilobits per second (kbps), that the Host link is capable of providing. When metrics are reported, the maximum data rate must be reported.
最大数据速率—主机链路能够提供的最大理论数据速率，单位为千比特每秒（kbps）。报告指标时，必须报告最大数据速率。
Current data rate - the current data rate, in kilobits per second (kbps), achieved on the Host link. If there is no distinction between maximum data rate and current data rate, current data rate should equal to the maximum data rate.
当前数据速率—主机链路上实现的当前数据速率，单位为千比特每秒（kbps）。如果最大数据速率和当前数据速率之间没有区别，则当前数据速率应等于最大数据速率。
Latency - the transmission delay that a packet encounters as it is transmitted over the Host link. This is reported in absolute delay, milliseconds. If latency cannot be calculated, a value of 0 should be reported.
延迟-数据包在主机链路上传输时遇到的传输延迟。这是以绝对延迟（毫秒）为单位报告的。如果无法计算延迟，则应报告值0。
Resources - a percentage, 0-100, representing the amount of remaining or available resources, such as battery power. If resources cannot be calculated, a value of 100 should be reported.
资源-百分比，0-100，表示剩余或可用资源的数量，如电池电量。如果无法计算资源，则应报告值100。
Relative Link Quality (RLQ) - a non-dimensional number, 0-100, representing the relative link quality. A value of 100 represents a link of the highest quality. If the RLQ cannot be calculated, a value of 100 should be reported.
相对链路质量（RLQ）-表示相对链路质量的无量纲数字，0-100。值100表示具有最高质量的链接。如果无法计算RLQ，则应报告值100。
The PPPoE Active Discovery Quality (PADQ) packet can be used to query link metrics by setting the PADQ Metric Tag Length to zero.
PPPoE主动发现质量（PADQ）数据包可用于通过将PADQ度量标记长度设置为零来查询链路度量。
An example packet is shown in Appendix B.
附录B中显示了一个示例数据包。
This specification defines the optional use of TLV Tags in the PPP Session Stage. The first field following the PPP Session Stage LENGTH must be checked. If the value is equal to the PPP Protocol identifier (0xc021), then normal packet (payload) processing occurs. When the field following the PPP Session Stage LENGTH is not the PPP Protocol identifier (0xc021), a TLV is assumed. In this case, the Tag length is subtracted from the overall payload length.
本规范定义了在PPP会话阶段可选使用TLV标记。必须检查PPP会话阶段长度后的第一个字段。如果该值等于PPP协议标识符（0xc021），则发生正常的数据包（有效负载）处理。当PPP会话阶段长度后面的字段不是PPP协议标识符（0xc021）时，假定TLV。在这种情况下，标签长度从总有效负载长度中减去。
The Credit Tag is the only optional TLV permitted in the PPP Session Stage. The Credit Tag TLV is used to support in-band flow control.
信用标签是PPP会话阶段允许的唯一可选TLV。信用标签TLV用于支持带内流量控制。
A PPP Session Stage packet with Credits is shown in Appendix B.
带有信用的PPP会话阶段数据包如附录B所示。
For a given session, credit grants exchanged in the Discovery Stage, PADG-PADC, are referred to as out-of-band. Credit grants exchanged in the PPP Session Stage are referred to as in-band. Credit processing is only applied to the packets transmitted in the PPP Session Stage.
对于给定会话，在发现阶段（PADG-PADC）中交换的信用授权称为带外。PPP会话阶段交换的信贷补助称为带内。信用处理仅应用于PPP会话阶段中传输的数据包。
Out-of-band credit management is handled by periodic exchange of the PPPoE Active Discovery Grant (PADG) and PPPoE Active Discovery Credit (PADC) packets.
带外信用管理通过定期交换PPPoE主动发现授权（PADG）和PPPoE主动发现信用（PADC）数据包来处理。
In-band credit management allows credits to be incrementally granted with each PPP Session Stage packet. These in-band incremental credit grants are not explicitly unacknowledged. However, they are reflected in the in-band credit flow from the peer node. This offers the greatest credit granting efficiency when traffic rates are high.
带内信用管理允许在每个PPP会话阶段数据包中增量授予信用。这些带内增量信贷授予未明确确认。但是，它们反映在来自对等节点的带内信用流中。这在流量较高时提供了最大的信贷授予效率。
Once agreed upon during the Discovery Stage, credit grants are required to transmit packets in the PPP Session Stage. A node must grant credits to its peer, before the peer can transmit packets to the granting node.
一旦在发现阶段达成一致，就需要信用授权来在PPP会话阶段传输数据包。节点必须先向其对等方授予信用，然后对等方才能将数据包发送给授予节点。
Credits are granted incrementally in the forward direction. Locally, a node manages the credits that it has granted to a peer, as well as the credits that a peer has granted to it.
学分按正向递增方式授予。在本地，节点管理它授予对等方的信用以及对等方授予它的信用。
Grants received from a peer are added to a local running credit counter. The accumulated credits are decremented with each packet the node transmits to the peer. When the running counter reaches zero, the node stops transmitting packets to the peer. The values of the PADC are not simply an echo of the PADG. They represent the current internal FCN/BCN values of that node.
从对等方收到的授权将添加到本地运行的信用计数器。累积的信用随着节点发送给对等方的每个分组而递减。当运行计数器达到零时，节点停止向对等方发送数据包。PADC的值不仅仅是PADG的回声。它们表示该节点的当前内部FCN/BCN值。
To manage the credits that a node has granted, the node maintains a running counter. With each PPP Session Stage packet received from the peer, the running counter is decremented. When the running counter reaches zero, no additional packets are expected. The node incrementally grants more credits to the peer to maintain packet flow. Packets received when granted credits that have been exhausted are discarded.
为了管理节点已授予的积分，该节点维护一个运行计数器。当从对等方接收到每个PPP会话阶段数据包时，运行计数器递减。当运行计数器达到零时，不需要额外的数据包。节点递增地向对等方授予更多的信用，以维持数据包流。当授予的信用已耗尽时接收的数据包将被丢弃。
The largest possible credit limit is 0x0ffff. If an incremental credit grant causes the accumulated count to exceed this value, the max value is used.
可能的最大信用额度为0x0ffff。如果增量信贷授予导致累计计数超过此值，则使用最大值。
One unit of credit represents 64-bytes, so a grant of 4 credits translates to 256 bytes.
一个学分单位代表64个字节，因此授予4个学分将转换为256个字节。
When a node does not receive a PADC packet in response to a PADG within a specified amount of time, it should transmit a new PADG packet with zero credits, using the same sequence number and double the waiting period. A PADC response with the associated sequence number will indicate whether or not the previously granted credits were accumulated. If they were not, a PADG with credits, with an incremented sequence number, should be transmitted. This process should be repeated until granted credits are properly acknowledged or as many times as desired.
当节点在指定的时间内没有收到PADG响应的PADC数据包时，它应该使用相同的序列号和两倍的等待时间来发送一个新的零信用PADG数据包。带有相关序列号的PADC响应将指示先前授予的积分是否已累积。如果没有，则应传输带有信用的PADG，序列号递增。应重复此过程，直到正确确认授予的学分，或根据需要重复多次。
When a node does not receive a PADQ metric packet within a specified amount of time, it should resend the PADQ query packet and double the waiting period. This can be repeated as many times as desired.
当节点在指定的时间内没有收到PADQ度量数据包时，它应该重新发送PADQ查询数据包并将等待时间延长一倍。这可以根据需要重复多次。
A node may autonomously generate PADQ metric packets. The rate of autonomously generated PADQ metric packets may need to be throttled so as not to overrun the peer.
节点可以自主地生成PADQ度量分组。可能需要限制自主生成的PADQ度量数据包的速率，以避免溢出对等方。
The sending and receiving of PPPoE control packets are independent of credit counts. For example, a node must always be able to receive a PADG and send a PADC.
PPPoE控制数据包的发送和接收与信用计数无关。例如，节点必须始终能够接收PADG并发送PADC。
During normal operation, nodes may disagree about the number of credits. Operational credit mismatches would occur due to packets in transit on the wire. Much larger credit mismatches can occur if there are transmission errors. To correct these larger errors, the BCN fields of the PADG and PADC packets and in-band credit grants from a peer should be used by the receiving node to set the credit values of its peer.
在正常操作过程中，节点可能会对信用数产生分歧。由于数据包在线路上传输，操作信用不匹配会发生。如果存在传输错误，则可能发生更大的信用错配。为了纠正这些较大的错误，接收节点应使用PADG和PADC数据包的BCN字段以及来自对等方的带内信用授权来设置其对等方的信用值。
IANA has assigned the following PPPoE TAG Values as noted in [3]:
IANA已分配[3]中所述的以下PPPoE标签值：
TAG Value TAG Name Tag Description Reference
----------- ------------------- --------------------- ---------
262 0x0106 Credits See the reference [RFC4938]
263 0x0107 Metrics See the reference [RFC4938]
264 0x0108 Sequence Number See the reference [RFC4938]
TAG Value TAG Name Tag Description Reference
----------- ------------------- --------------------- ---------
262 0x0106 Credits See the reference [RFC4938]
263 0x0107 Metrics See the reference [RFC4938]
264 0x0108 Sequence Number See the reference [RFC4938]
IANA has assigned the following PPPoE Code fields as noted in [3]:
IANA已分配[3]中所述的以下PPPoE代码字段：
Code PPPoE Packet Name Description Reference
-------- ----------------------------- ----------------- ---------
10 0x0a PADG, Session-Grant See the reference [RFC4938]
11 0x0b PADC, Session-Credit Response See the reference [RFC4938]
12 0x0c PADQ, Quality See the reference [RFC4938]
Code PPPoE Packet Name Description Reference
-------- ----------------------------- ----------------- ---------
10 0x0a PADG, Session-Grant See the reference [RFC4938]
11 0x0b PADC, Session-Credit Response See the reference [RFC4938]
12 0x0c PADQ, Quality See the reference [RFC4938]
This memo defines a mechanism for adding flow control to the existing PPP Over Ethernet (PPPoE) sessions. These extensions are subsequent to the existing PPPoE security mechanisms as described in RFC 2516 [2]. It is required that the Service Tag and Session ID always be validated prior to processing credits.
此备忘录定义了一种机制，用于向现有的以太网PPP（PPPoE）会话添加流量控制。这些扩展是继RFC 2516[2]中描述的现有PPPoE安全机制之后的扩展。在处理信用证之前，要求始终验证服务标签和会话ID。
Appendix A: Tag Values
附录A：标签值
Feature Tag_Types and Tag_Values
要素标记类型和标记值
0x0106 Credits
0x0106学分
This tag contains the Forward Credit Notification (FCN) and the Backward Credit Notification (BCN). The Credit Tag TLV is OPTIONAL with the PADR, PADS, and the PPPoE data payload packet (ETHER_TYPE=8864).
此标记包含正向信用通知（FCN）和反向信用通知（BCN）。信用标签TLV对于PADR、PADS和PPPoE数据有效载荷包（ETHER_TYPE=8864）是可选的。
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Type = 0x0106 | Tag Length=0x04 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FCN | BCN |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Type = 0x0106 | Tag Length=0x04 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FCN | BCN |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0x0107 Metrics
0x0107指标
This tag is used to report the link quality and performance. The Metrics Tag TLV contains the Receive Only indicator, Resource status, Latency, Relative Link Quality (RLQ), Current data rate, and Maximum data rate. The Metrics TLV is required by the PADQ packet.
This tag is used to report the link quality and performance. The Metrics Tag TLV contains the Receive Only indicator, Resource status, Latency, Relative Link Quality (RLQ), Current data rate, and Maximum data rate. The Metrics TLV is required by the PADQ packet.translate error, please retry
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Type = 0x0107 | Tag Length=0x0A |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |R| RLQ | Resource |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Latency (MS) | Current Datarate (kbps) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Maximum Datarate (kbps) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Type = 0x0107 | Tag Length=0x0A |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |R| RLQ | Resource |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Latency (MS) | Current Datarate (kbps) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Maximum Datarate (kbps) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0x0108 Sequence Number
0x0108序列号
This tag is used to carry a unique 16-bit sequence number in order to identify a specific request and the associated response. The sequence number should be initialized to zero and incremented by one for each new request. For retransmitted packets, the same sequence number that was used in the previous packet transmission is repeated. The PADG and PADC packets require the Sequence Number Tag.
该标签用于携带唯一的16位序列号，以识别特定请求和相关响应。序列号应初始化为零，并为每个新请求递增1。对于重新传输的数据包，重复先前数据包传输中使用的相同序列号。PADG和PADC数据包需要序列号标签。
For example, the sequence number sent in the PADG request is echoed in the PADC response. This ties a specific PADC response to a specific PADG request.
例如，PADG请求中发送的序列号将在PADC响应中回响。这将特定的PADC响应与特定的PADG请求联系起来。
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Type = 0x0108 | Tag Length=0x02 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Type = 0x0108 | Tag Length=0x02 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Appendix B: Example Message Formats
附录B：示例消息格式
A PADR packet with OPTIONAL Credit Tag Type 0x0106:
具有可选信用标签类型0x0106的PADR数据包：
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Access_Concentrator_mac_addr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Access_Concentrator_mac_addr(c)| Host_mac_addr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Host_mac_addr (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ETHER_TYPE = 0x8863 | v = 1 | t = 1 | CODE = 0x19 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SESSION_ID = 0x1234 | LENGTH = 0x0C |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Type = 0x0101 | Tag Length=0x00 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Type = 0x0106 | Tag Length=0x04 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FCN | BCN |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Access_Concentrator_mac_addr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Access_Concentrator_mac_addr(c)| Host_mac_addr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Host_mac_addr (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ETHER_TYPE = 0x8863 | v = 1 | t = 1 | CODE = 0x19 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SESSION_ID = 0x1234 | LENGTH = 0x0C |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Type = 0x0101 | Tag Length=0x00 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Type = 0x0106 | Tag Length=0x04 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FCN | BCN |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A PADS packet with OPTIONAL Credit Tag Type 0x0106:
具有可选信用标签类型0x0106的PADS数据包：
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Access_Concentrator_mac_addr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Access_Concentrator_mac_addr(c)| Host_mac_addr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Host_mac_addr (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ETHER_TYPE = 0x8863 | v = 1 | t = 1 | CODE = 0x65 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SESSION_ID = 0x1234 | LENGTH = 0x0C |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Type = 0x0101 | Tag Length=0x00 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Type = 0x0106 | Tag Length=0x04 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FCN | BCN |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Access_Concentrator_mac_addr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Access_Concentrator_mac_addr(c)| Host_mac_addr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Host_mac_addr (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ETHER_TYPE = 0x8863 | v = 1 | t = 1 | CODE = 0x65 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SESSION_ID = 0x1234 | LENGTH = 0x0C |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Type = 0x0101 | Tag Length=0x00 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Type = 0x0106 | Tag Length=0x04 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FCN | BCN |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A PADG packet with Credit Tag Type 0x0106:
信用标签类型为0x0106的PADG数据包：
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination_mac_addr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination_mac_addr(c) | Source_mac_addr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source mac_addr (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ETHER_TYPE = 0x8863 | v = 1 | t = 1 | CODE = 0x0A |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SESSION_ID = 0x1234 | LENGTH = 0x0E |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Type = 0x0108 | Tag Length=0x02 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number | Tag Type = 0x0106 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Length=0x04 | FCN |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BCN |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination_mac_addr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination_mac_addr(c) | Source_mac_addr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source mac_addr (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ETHER_TYPE = 0x8863 | v = 1 | t = 1 | CODE = 0x0A |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SESSION_ID = 0x1234 | LENGTH = 0x0E |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Type = 0x0108 | Tag Length=0x02 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number | Tag Type = 0x0106 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Length=0x04 | FCN |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BCN |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A PADC packet with Credit Tag Type 0x0106:
信用标签类型为0x0106的PADC数据包：
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination_mac_addr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination_mac_addr(c) | Source_mac_addr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source mac_addr (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ETHER_TYPE = 0x8863 | v = 1 | t = 1 | CODE = 0x0B |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SESSION_ID = 0x1234 | LENGTH = 0x0E |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Type = 0x0108 | Tag Length=0x02 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number | Tag Type = 0x0106 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Length=0x04 | FCN |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BCN |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination_mac_addr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination_mac_addr(c) | Source_mac_addr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source mac_addr (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ETHER_TYPE = 0x8863 | v = 1 | t = 1 | CODE = 0x0B |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SESSION_ID = 0x1234 | LENGTH = 0x0E |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Type = 0x0108 | Tag Length=0x02 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number | Tag Type = 0x0106 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Length=0x04 | FCN |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BCN |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A PADQ packet to query for the link metrics: This is indicated by the Metric Tag Length=0.
用于查询链路度量的PADQ数据包：这由度量标记长度=0表示。
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Access_Concentrator_mac_addr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Access_Concentrator_mac_addr(c)| Host_mac_addr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Host_mac_addr (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ETHER_TYPE = 0x8863 | v = 1 | t = 1 | CODE = 0x0C |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SESSION_ID = 0x1234 | LENGTH = 0x08 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Type = 0x0101 | Tag Length=0x00 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Type = 0x0107 | Tag Length=0x00 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Access_Concentrator_mac_addr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Access_Concentrator_mac_addr(c)| Host_mac_addr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Host_mac_addr (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ETHER_TYPE = 0x8863 | v = 1 | t = 1 | CODE = 0x0C |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SESSION_ID = 0x1234 | LENGTH = 0x08 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Type = 0x0101 | Tag Length=0x00 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Type = 0x0107 | Tag Length=0x00 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A PADQ packet with Metric Tag Type 0x0107:
度量标记类型为0x0107的PADQ数据包：
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Access_Concentrator_mac_addr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Access_Concentrator_mac_addr(c)| Host_mac_addr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Host_mac_addr (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ETHER_TYPE = 0x8863 | v = 1 | t = 1 | CODE = 0x0C |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SESSION_ID = 0x1234 | LENGTH = 0x12 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Type = 0x0101 | Tag Length=0x00 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Type = 0x0107 | Tag Length=0x0A |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |R| RLQ | Resource |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Latency (MS) | Current Datarate (kbps) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Maximum Datarate (kbps) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Access_Concentrator_mac_addr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Access_Concentrator_mac_addr(c)| Host_mac_addr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Host_mac_addr (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ETHER_TYPE = 0x8863 | v = 1 | t = 1 | CODE = 0x0C |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SESSION_ID = 0x1234 | LENGTH = 0x12 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Type = 0x0101 | Tag Length=0x00 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Type = 0x0107 | Tag Length=0x0A |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |R| RLQ | Resource |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Latency (MS) | Current Datarate (kbps) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Maximum Datarate (kbps) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A PPP LCP packet with optional Credit Tag Type 0x0106:
具有可选信用标签类型0x0106的PPP LCP数据包：
While the PPP protocol value is shown (0xc021), the PPP payload is left to the reader. This is a packet from the Host to the Access Concentrator.
当显示PPP协议值（0xc021）时，PPP有效负载留给读卡器。这是从主机到访问集中器的数据包。
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Access_Concentrator_mac_addr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Access_Concentrator_mac_addr(c)| Host_mac_addr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Host_mac_addr (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ETHER_TYPE = 0x8864 | v = 1 | t = 1 | CODE = 0x00 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SESSION_ID = 0x1234 | LENGTH = (payload) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Type = 0x0106 | Tag Length=0x04 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FCN | BCN |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PPP PROTOCOL = 0xc021 | PPP payload ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Access_Concentrator_mac_addr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Access_Concentrator_mac_addr(c)| Host_mac_addr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Host_mac_addr (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ETHER_TYPE = 0x8864 | v = 1 | t = 1 | CODE = 0x00 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SESSION_ID = 0x1234 | LENGTH = (payload) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag Type = 0x0106 | Tag Length=0x04 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FCN | BCN |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PPP PROTOCOL = 0xc021 | PPP payload ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Acknowledgements
致谢
The authors would like to acknowledge the influence and contributions from Billy Moon, Fred Baker, Stan Ratliff, and Ed Paradise.
作者要感谢Billy Moon、Fred Baker、Stan Ratliff和Ed Paradise的影响和贡献。
Normative References
规范性引用文件
[1] Simpson, W., Ed., "The Point-to-Point Protocol (PPP)", STD 51, RFC 1661, July 1994.
[1] 辛普森，W.，编辑，“点对点协议（PPP）”，STD 51，RFC 1661994年7月。
[2] Mamakos, L., Lidl, K., Evarts, J., Carrel, D., Simone, D., and R. Wheeler, "A Method for Transmitting PPP Over Ethernet (PPPoE)", RFC 2516, February 1999.
[2] Mamakos，L.，Lidl，K.，Evarts，J.，Carrel，D.，Simone，D.，和R.Wheeler，“通过以太网传输PPP（PPPoE）的方法”，RFC 2516，1999年2月。
[3] Arberg, P. and V. Mammoliti, "IANA Considerations for PPP over Ethernet (PPPoE)", RFC 4937, June 2007.
[3] Arberg，P.和V.Mammoliti，“以太网PPP（PPPoE）的IANA考虑因素”，RFC 4937，2007年6月。
Authors' Addresses
作者地址
Bo Berry Cisco 170 West Tasman Drive San Jose, CA 95134 USA EMail: bberry@cisco.com
Bo Berry Cisco 170美国加利福尼亚州圣何塞西塔斯曼大道95134号电子邮件：bberry@cisco.com
Howard Holgate Cisco 170 West Tasman Drive San Jose, CA 95134 USA EMail: hholgate@cisco.com
Howard Holgate Cisco 170西塔斯曼大道圣何塞，加利福尼亚州95134美国电子邮件：hholgate@cisco.com
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完整版权声明
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确认
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