Network Working Group R. Verma
Request for Comments: 3145 Deloitte Consulting
Category: Standards Track M. Verma
3Com Corporation
J. Carlson
Sun Microsystems
July 2001
Network Working Group R. Verma
Request for Comments: 3145 Deloitte Consulting
Category: Standards Track M. Verma
3Com Corporation
J. Carlson
Sun Microsystems
July 2001
L2TP Disconnect Cause Information
L2TP断开原因信息
Status of this Memo
本备忘录的状况
This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.
本文件规定了互联网社区的互联网标准跟踪协议，并要求进行讨论和提出改进建议。有关本协议的标准化状态和状态，请参考当前版本的“互联网官方协议标准”（STD 1）。本备忘录的分发不受限制。
Copyright Notice
版权公告
Copyright (C) The Internet Society (2001). All Rights Reserved.
版权所有（C）互联网协会（2001年）。版权所有。
Abstract
摘要
This document provides an extension to the Layer 2 Tunneling Protocol ("L2TP"), a mechanism for tunneling Point-to-Point Protocol (PPP) sessions. L2TP lacks a mechanism for a host to provide PPP-related disconnect cause information to another host. This information, provided by the extension described in this document, can be useful for accounting and debugging purposes.
本文档提供了对第2层隧道协议（“L2TP”）的扩展，这是一种隧道点对点协议（PPP）会话的机制。L2TP缺少主机向另一台主机提供PPP相关断开原因信息的机制。此信息由本文档中描述的扩展提供，可用于记帐和调试目的。
L2TP [1] defines a general-purpose mechanism for tunneling PPP over various media. By design, it insulates L2TP operation from the details of the PPP session that is being encapsulated by L2TP. There are, however, cases where it may be desirable for PPP-specific disconnect information to be provided to an L2TP host (L2TP Access Concentrator [LAC] or L2TP Network Server [LNS]) in a descriptive format. The lack of this information is especially a problem when the LAC and LNS are not owned or managed by the same entities.
L2TP[1]定义了一种通用机制，用于在各种媒体上对PPP进行隧道传输。根据设计，它将L2TP操作与L2TP封装的PPP会话的细节隔离开来。然而，在某些情况下，可能需要以描述性格式向L2TP主机（L2TP访问集中器[LAC]或L2TP网络服务器[LNS]）提供PPP特定的断开连接信息。当LAC和LN不是由同一实体拥有或管理时，缺乏此类信息尤其是一个问题。
The Result and Error Codes defined for L2TP specify only L2TP-specific disconnect information. This document provides an additional Attribute Value Pair (AVP), called PPP Disconnect Cause Code, that MAY be used by an L2TP host to provide PPP-specific
为L2TP定义的结果代码和错误代码仅指定L2TP特定的断开连接信息。本文档提供了一个额外的属性值对（AVP），称为PPP断开连接原因代码，L2TP主机可使用该属性值对提供特定于PPP的连接
disconnect information to its peer. This AVP should be used in conjunction with, and not as a replacement for, the L2TP Result and Error Code AVPs.
断开信息与对等方的连接。此AVP应与L2TP结果和错误代码AVP一起使用，而不是作为替代品。
The PPP Disconnect Cause Code AVP can also be used to provide a human-readable disconnect reason to the user. This AVP should not have any effect on either the functioning of the tunnel or the functioning of the PPP session; it is for informational and logging purposes only.
PPP断开原因代码AVP还可用于向用户提供人类可读的断开原因。该AVP不得对隧道的功能或PPP会话的功能产生任何影响；它仅用于信息和日志记录目的。
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 BCP 14 [2].
本文件中的关键词“必须”、“不得”、“要求”、“应”、“不应”、“应”、“不应”、“建议”、“可”和“可选”应按照BCP 14[2]中所述进行解释。
The AVP is valid in the L2TP Call-Disconnect-Notify (CDN) message only, and it MUST NOT be marked Mandatory.
AVP仅在L2TP Call Disconnect Notify（CDN）消息中有效，不得将其标记为强制。
The PPP Disconnect Cause Code AVP is encoded with Vendor ID 0 and an Attribute Type of PPP Disconnect Cause Code (46). The length of the Value field MUST be at least 11 octets. If the length is more than 11 octets, the additional octets MUST contain a descriptive text in UTF-8 [3] format that can be displayed to the user or in a log file. The format of the AVP is shown below.
PPP断开原因代码AVP使用供应商ID 0和PPP断开原因代码（46）的属性类型进行编码。值字段的长度必须至少为11个八位字节。如果长度超过11个八位字节，则附加的八位字节必须包含UTF-8[3]格式的描述性文本，该文本可以显示给用户或在日志文件中。AVP的格式如下所示。
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|M|H| rsvd | Length | Vendor ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Type | Disconnect Code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Control Protocol Number | Direction | Message...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|M|H| rsvd | Length | Vendor ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Type | Disconnect Code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Control Protocol Number | Direction | Message...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
Figure 1: PPP Disconnect Cause Code AVP
图1:PPP断开原因代码AVP
Mandatory (M) bit: MUST be 0.
强制（M）位：必须为0。
Hidden (H) bit: MAY be 1 if the attribute is hidden.
隐藏（H）位：如果属性隐藏，则可能为1。
Length: The length of the entire attribute in octets, expressed as a single octet. The length MUST be at least 11.
长度：以八位字节表示的整个属性的长度，表示为单个八位字节。长度必须至少为11。
Vendor ID: A two octet value in network byte order; set to 0 to indicate that this is an IETF-assigned attribute.
供应商ID：网络字节顺序的两个八位字节值；设置为0表示这是IETF分配的属性。
Attribute Type: A two octet value in network byte order; set to 46 (PPP Disconnect Cause Code).
属性类型：网络字节顺序的两个八位字节值；设置为46（PPP断开原因代码）。
Disconnect Code: A two octet value in network byte order. (Described in section 3 of this document.)
断开连接代码：网络字节顺序的两个八位字节值。（如本文件第3节所述。）
Control Protocol Number: The PPP Control Protocol number of the primary protocol known to have caused the error, if any. This field may be 0 unless mentioned otherwise in the description of the Disconnect Codes in section 3.
控制协议编号：已知导致错误的主协议的PPP控制协议编号（如果有）。除非第3节断开代码说明中另有说明，否则该字段可以为0。
Direction: A single octet value; specifies the direction in which the Disconnect Code applies.
方向：单个八位组值；指定断开代码的应用方向。
The valid values of this field are:
此字段的有效值为：
0: global error 1: at peer 2: at local 3-255: Reserved
0:全局错误1:在对等端2:在本地3-255:保留
This field SHOULD be 0 unless documented otherwise in the description of the specific Disconnect Code.
除非在特定断开代码的说明中另有说明，否则该字段应为0。
This section contains the list of well-known values of the Disconnect Code field in the PPP Disconnect Cause Code AVP. The IANA will maintain a registry of the up-to-date values (see section 5 of this document). These values should be used in conjunction with the Direction value and the Control Protocol Number field to interpret the specific error condition.
本节包含PPP断开原因代码AVP中断开代码字段的已知值列表。IANA将维护最新值的登记册（见本文件第5节）。这些值应与方向值和控制协议编号字段一起使用，以解释特定的错误条件。
Unless documented otherwise for a specific Disconnect Code, the Direction value SHOULD be 0.
除非对特定断开代码另有说明，否则方向值应为0。
The global error codes, given in the list below, are Disconnect Codes that do not relate to one particular PPP Control Protocol. The Control Protocol Number for these errors thus MUST be set to 0.
下表中给出的全局错误代码是与特定PPP控制协议无关的断开连接代码。因此，这些错误的控制协议号必须设置为0。
0 No information available.
0没有可用的信息。
1 Administrative disconnect.
1行政脱节。
2 Link Control Protocol (LCP) renegotiation at LNS disabled; LNS expects proxy LCP information, LAC did not send it.
2禁用LNS处的链路控制协议（LCP）重新协商；LNS需要代理LCP信息，LAC未发送该信息。
3 Normal Disconnection, LCP Terminate-Request sent.
3正常断开，发送LCP终止请求。
Valid Direction values are:
有效方向值为：
1: LCP Terminate-Request sent by peer 2: LCP Terminate-Request sent by local
1:对等端发送的LCP终止请求2:本地端发送的LCP终止请求
4 Compulsory encryption required by a PPP peer was refused by the other.
4 PPP对等方要求的强制加密被另一方拒绝。
Valid Direction values are:
有效方向值为：
1: Required by local; refused by peer
2: Required by peer; refused by local
1: Required by local; refused by peer
2: Required by peer; refused by local
The LCP error codes, listed below, are disconnect reasons that are directly related to the failure of PPP peers to negotiate mutually agreeable link parameters. The Control Protocol Number for these errors MUST be set to C021 hexadecimal (LCP).
下面列出的LCP错误代码是与PPP对等方未能协商双方同意的链路参数直接相关的断开原因。这些错误的控制协议编号必须设置为C021十六进制（LCP）。
5 FSM (Finite State Machine) Timeout error. (PPP event "TO-".)
5 FSM（有限状态机）超时错误。（PPP活动“至-”）
6 No recognizable LCP packets were received.
6未收到可识别的LCP数据包。
7 LCP failure: Magic Number error; link possibly looped back.
7 LCP故障：幻数错误；链接可能已回环。
8 LCP link failure: Echo Request timeout.
8 LCP链路故障：回显请求超时。
9 Peer has unexpected Endpoint-Discriminator for existing Multilink PPP (MP) bundle.
9对等方对现有多链路PPP（MP）捆绑包具有意外的端点鉴别器。
10 Peer has unexpected MRRU for existing MP bundle.
10对等方对现有MP捆绑包具有意外的MRRU。
11 Peer has unexpected Short-Sequence-Number option for existing MP bundle.
11对等方对现有MP捆绑包具有意外的短序列号选项。
12 Compulsory call-back required by a PPP peer was refused by the other.
12 PPP对等方要求的强制回拨被另一方拒绝。
Valid Direction values are:
有效方向值为：
1: Required by local; refused by peer
2: Required by peer; refused by local
1: Required by local; refused by peer
2: Required by peer; refused by local
The authentication error codes, listed below, are disconnect reasons that are directly related to authentication failures between the PPP peers. The Control Protocol Number for such errors MUST correspond to the PPP Control Protocol number for the authentication protocol in use.
下面列出的身份验证错误代码是与PPP对等方之间的身份验证失败直接相关的断开连接原因。此类错误的控制协议编号必须与正在使用的认证协议的PPP控制协议编号相对应。
13 FSM Timeout error.
13 FSM超时错误。
14 Peer has unexpected authenticated name for existing MP bundle.
14对等方具有现有MP捆绑包的意外身份验证名称。
15 PPP authentication failure: Authentication protocol unacceptable.
15 PPP身份验证失败：身份验证协议不可接受。
Valid Direction values are:
有效方向值为：
1: All local authentication protocols were rejected by the peer.
1:对等方拒绝了所有本地身份验证协议。
2: All authentication protocols requested by peer were unacceptable or unimplemented locally.
2：对等方请求的所有身份验证协议均不可接受或未在本地实现。
16 PPP authentication failure: Authentication failed (bad name, password, or secret).
16 PPP身份验证失败：身份验证失败（名称、密码或密码错误）。
Valid Direction values are:
有效方向值为：
1: Authentication of peer identity by local system. 2: Authentication of local identity by peer system.
1：通过本地系统验证对等身份。2：通过对等系统验证本地身份。
NCP Errors are disconnect reasons that are directly related to the failure of PPP peers to negotiate a mutually agreeable set of parameters for the network protocols. The Control Protocol Number for such errors SHOULD correspond to the PPP Network Control Protocol number in use. Where multiple network protocols are in use, multiple copies of this AVP MAY be given to indicate failure reasons for each NCP. Otherwise, if only one copy of the AVP is given, the Control Protocol Number SHOULD correspond to the last (most recent) failing NCP.
NCP错误是断开连接的原因，与PPP对等方无法协商一组相互同意的网络协议参数直接相关。此类错误的控制协议编号应与正在使用的PPP网络控制协议编号相对应。在使用多个网络协议的情况下，可提供该AVP的多个副本，以指示每个NCP的故障原因。否则，如果仅提供一份AVP副本，则控制协议编号应与最后一次（最近一次）失败的NCP相对应。
17 FSM Timeout error.
17 FSM超时错误。
18 No NCPs available (all disabled or rejected); no NCPs went to Opened state. (Control Protocol Number may be zero only if neither peer has enabled NCPs.)
18无可用NCP（全部禁用或被拒绝）；没有NCP进入开放状态。（只有当两个对等方均未启用NCP时，控制协议编号才可以为零。）
19 NCP failure: failed to converge on acceptable addresses.
19 NCP失败：未能聚合到可接受的地址。
Valid Direction values are:
有效方向值为：
1: Too many Configure-Naks received from peer. 2: Too many Configure-Naks sent to peer.
1:从对等方接收的配置NAK太多。2:发送到对等方的配置NAK太多。
20 NCP failure: user not permitted to use any addresses.
20 NCP故障：用户不允许使用任何地址。
Valid Direction values are:
有效方向值为：
1: Local link address not acceptable to peer. 2: Remote link address not acceptable to local system.
1：对等方不接受本地链接地址。2：本地系统不接受远程链路地址。
This AVP MAY may be sent by either the LNS or LAC. It is generally expected that this AVP will be most useful in sending notification from the LNS to LAC in the compulsory tunneling case, although it is not precluded from use in any other case.
该AVP可由LNS或LAC发送。一般认为，在强制隧道情况下，该AVP在从LN向LAC发送通知时最为有用，尽管在任何其他情况下，该AVP都不排除使用。
A draft form of this AVP used Vendor ID 43 (3Com Corporation) and vendor-specific Attribute Type 46. Implementations MAY accept AVPs with these values as equivalent to the message described in this document, but SHOULD NOT transmit an AVP using these values.
此AVP的草稿表单使用供应商ID 43（3Com Corporation）和供应商特定属性类型46。实现可以接受具有这些值的AVP，将其视为等同于本文档中描述的消息，但不应使用这些值传输AVP。
The integrity and confidentiality of this AVP relies on the underlying L2TP security mechanisms. It is intended for logging and diagnostic purposes in the event of PPP link failure and should not pose a threat to system security, but the AVP MAY be hidden as described in section 4.3 of RFC 2661.
此AVP的完整性和机密性依赖于底层L2TP安全机制。它用于PPP链路故障时的日志记录和诊断目的，不应对系统安全构成威胁，但AVP可以按照RFC 2661第4.3节的说明隐藏。
The defined extension does not provide information that would be useful to an attacker. Future extensions should not be defined to lessen security. For instance, it is inappropriate to provide distinguishing information that would inform the peer that a given authentication name is correct, but the password/secret is incorrect.
定义的扩展不提供对攻击者有用的信息。不应定义将来的扩展来降低安全性。例如，不应提供区别信息，告知对等方给定的身份验证名称是正确的，但密码/机密是不正确的。
IANA has assigned an L2TP Attribute Type value of 46 for the PPP Disconnect Cause Code defined in Section 2.
IANA为第2节中定义的PPP断开原因代码分配了L2TP属性类型值46。
This AVP includes an enumerated cause code value, called the "Disconnect Code." Values 0 through 20 are described in this document. Values 21 through 32767 (inclusive) are assigned by the IANA subject to IESG Approval. Values 32768 through 65279 (inclusive) are assigned by the IANA on a First Come First Served basis, and are intended for vendor-specific features. Values 65280 through 65535 (inclusive) are allocated for Private or Experimental Use, and no assignment through the IANA is expected.
此AVP包括一个枚举的原因代码值，称为“断开连接代码”。本文档中描述了值0到20。值21至32767（含）由IANA分配，但需经IESG批准。IANA按照先到先得的原则分配32768到65279（含）的值，用于特定于供应商的功能。值65280到65535（含）分配给私人或实验使用，预计不会通过IANA分配。
[1] Townsley, W., Valencia, A., Rubens, A., Pall, G., Zorn, G. and B. Palter, "Layer 2 Tunnel Protocol (L2TP)", RFC 2661, August 1999.
[1] 汤斯利，W.，巴伦西亚，A.，鲁本斯，A.，帕尔，G.，佐恩，G.和B.帕尔特，“第二层隧道协议（L2TP）”，RFC 26611999年8月。
[2] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[2] Bradner，S.，“RFC中用于表示需求水平的关键词”，BCP 14，RFC 2119，1997年3月。
[3] Yergeau, F., "UTF-8, a transformation format of ISO 10646", RFC 2279, January 1998.
[3] “UTF-8，ISO 10646的转换格式”，RFC 2279，1998年1月。
The authors thank W. Mark Townsley and Thomas Narten for their comments and help.
作者感谢W.MarkTownsley和ThomasNarten的评论和帮助。
W. Mark Townsley Cisco Systems 7025 Kit Creek Road PO Box 14987 Research Triangle Park, NC 27709
美国北卡罗来纳州三角研究公园14987号吉特克里克路邮政信箱7025号马克·汤斯利思科系统公司
EMail: townsley@cisco.com
EMail: townsley@cisco.com
Rohit Verma 180 N. Stetson Avenue Chicago IL 60601
伊利诺伊州芝加哥Stetson大道北180号Rohit Verma 60601
Phone: +1 312 374 2475
Fax: +1 312 870 2475
EMail: rverma@dc.com
Phone: +1 312 374 2475
Fax: +1 312 870 2475
EMail: rverma@dc.com
Madhvi Verma 3800 Golf Road Rolling Meadows IL 60008
伊利诺伊州马德维·维尔马3800高尔夫公路起伏草地60008
Phone: +1 847 262 2987
Fax: +1 847 262 2255
EMail: Madhvi_Verma@3com.com
Phone: +1 847 262 2987
Fax: +1 847 262 2255
EMail: Madhvi_Verma@3com.com
James Carlson Sun Microsystems 1 Network Drive MS UBUR02-212 Burlington MA 01803-2757
James Carlson Sun Microsystems 1网络驱动器MS UBUR02-212马萨诸塞州伯灵顿01803-2757
Phone: +1 781 442 2084
Fax: +1 781 442 1677
EMail: james.d.carlson@sun.com
Phone: +1 781 442 2084
Fax: +1 781 442 1677
EMail: james.d.carlson@sun.com
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This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
本文件和其中包含的信息是按“原样”提供的，互联网协会和互联网工程任务组否认所有明示或暗示的保证，包括但不限于任何保证，即使用本文中的信息不会侵犯任何权利，或对适销性或特定用途适用性的任何默示保证。
Acknowledgement
确认
Funding for the RFC Editor function is currently provided by the Internet Society.
RFC编辑功能的资金目前由互联网协会提供。