Internet Engineering Task Force (IETF) K. Patel
Request for Comments: 8538 Arrcus
Updates: 4724 R. Fernando
Category: Standards Track Cisco Systems
ISSN: 2070-1721 J. Scudder
J. Haas
Juniper Networks
March 2019
Internet Engineering Task Force (IETF) K. Patel
Request for Comments: 8538 Arrcus
Updates: 4724 R. Fernando
Category: Standards Track Cisco Systems
ISSN: 2070-1721 J. Scudder
J. Haas
Juniper Networks
March 2019
Notification Message Support for BGP Graceful Restart
BGP正常重启的通知消息支持
Abstract
摘要
The BGP Graceful Restart mechanism defined in RFC 4724 limits the usage of BGP Graceful Restart to BGP messages other than BGP NOTIFICATION messages. This document updates RFC 4724 by defining an extension that permits the Graceful Restart procedures to be performed when the BGP speaker receives a BGP NOTIFICATION message or the Hold Time expires. This document also defines a new subcode for BGP Cease NOTIFICATION messages; this new subcode requests a full session restart instead of a Graceful Restart.
RFC 4724中定义的BGP优雅重启机制将BGP优雅重启的使用限制为BGP通知消息以外的BGP消息。本文档通过定义一个扩展来更新RFC 4724，该扩展允许在BGP扬声器收到BGP通知消息或保持时间到期时执行优雅的重启过程。本文件还定义了BGP停止通知消息的新子代码；此新子代码请求完全会话重新启动，而不是正常重新启动。
Status of This Memo
关于下段备忘
This is an Internet Standards Track document.
这是一份互联网标准跟踪文件。
This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 7841.
本文件是互联网工程任务组（IETF）的产品。它代表了IETF社区的共识。它已经接受了公众审查，并已被互联网工程指导小组（IESG）批准出版。有关互联网标准的更多信息，请参见RFC 7841第2节。
Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at https://www.rfc-editor.org/info/rfc8538.
有关本文件当前状态、任何勘误表以及如何提供反馈的信息，请访问https://www.rfc-editor.org/info/rfc8538.
Copyright Notice
版权公告
Copyright (c) 2019 IETF Trust and the persons identified as the document authors. All rights reserved.
版权（c）2019 IETF信托基金和被确定为文件作者的人员。版权所有。
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.
本文件受BCP 78和IETF信托有关IETF文件的法律规定的约束(https://trustee.ietf.org/license-info)自本文件出版之日起生效。请仔细阅读这些文件，因为它们描述了您对本文件的权利和限制。从本文件中提取的代码组件必须包括信托法律条款第4.e节中所述的简化BSD许可证文本，并提供简化BSD许可证中所述的无担保。
Table of Contents
目录
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Modifications to BGP Graceful Restart Capability . . . . . . 3
3. BGP Hard Reset Subcode . . . . . . . . . . . . . . . . . . . 4
3.1. Sending a Hard Reset . . . . . . . . . . . . . . . . . . 4
3.2. Receiving a Hard Reset . . . . . . . . . . . . . . . . . 4
4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.1. Rules for the Receiving Speaker . . . . . . . . . . . . . 6
5. Use of Hard Reset . . . . . . . . . . . . . . . . . . . . . . 7
5.1. When to Send a Hard Reset . . . . . . . . . . . . . . . . 7
5.2. Interaction with Other Specifications . . . . . . . . . . 7
6. Management Considerations . . . . . . . . . . . . . . . . . . 8
7. Operational Considerations . . . . . . . . . . . . . . . . . 8
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
9. Security Considerations . . . . . . . . . . . . . . . . . . . 9
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
10.1. Normative References . . . . . . . . . . . . . . . . . . 9
10.2. Informative References . . . . . . . . . . . . . . . . . 9
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Modifications to BGP Graceful Restart Capability . . . . . . 3
3. BGP Hard Reset Subcode . . . . . . . . . . . . . . . . . . . 4
3.1. Sending a Hard Reset . . . . . . . . . . . . . . . . . . 4
3.2. Receiving a Hard Reset . . . . . . . . . . . . . . . . . 4
4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.1. Rules for the Receiving Speaker . . . . . . . . . . . . . 6
5. Use of Hard Reset . . . . . . . . . . . . . . . . . . . . . . 7
5.1. When to Send a Hard Reset . . . . . . . . . . . . . . . . 7
5.2. Interaction with Other Specifications . . . . . . . . . . 7
6. Management Considerations . . . . . . . . . . . . . . . . . . 8
7. Operational Considerations . . . . . . . . . . . . . . . . . 8
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
9. Security Considerations . . . . . . . . . . . . . . . . . . . 9
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
10.1. Normative References . . . . . . . . . . . . . . . . . . 9
10.2. Informative References . . . . . . . . . . . . . . . . . 9
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
For many classes of errors, BGP must send a NOTIFICATION message and reset the peering session to handle the error condition. The BGP Graceful Restart mechanism defined in [RFC4724] requires that normal BGP procedures defined in [RFC4271] be followed when a NOTIFICATION message is sent or received. This document defines an extension to BGP Graceful Restart that permits the Graceful Restart procedures to be performed when the BGP speaker receives a NOTIFICATION message or the Hold Time expires. This permits the BGP speaker to avoid flapping reachability and continue forwarding while the BGP speaker restarts the session to handle errors detected in BGP.
对于许多类型的错误，BGP必须发送通知消息并重置对等会话以处理错误情况。[RFC4724]中定义的BGP优雅重启机制要求在发送或接收通知消息时遵循[RFC4271]中定义的正常BGP过程。本文档定义了BGP优雅重启的扩展，允许在BGP扬声器收到通知消息或等待时间到期时执行优雅重启过程。这允许BGP扬声器在BGP扬声器重新启动会话以处理在BGP中检测到的错误时，避免切换可达性并继续转发。
At a high level, this document can be summed up as follows. When a BGP session is reset, both speakers operate as "Receiving Speakers" according to [RFC4724], meaning they retain each other's routes. This is also true for HOLDTIME expiration. The functionality can be defeated by sending a BGP Cease NOTIFICATION message with the Hard Reset subcode. If a Hard Reset is used, a full session reset is performed.
从高层次上讲，本文件可概括如下。当BGP会话重置时，根据[RFC4724]，两个扬声器都作为“接收扬声器”工作，这意味着它们保留彼此的路由。对于HOLDTIME过期也是如此。通过发送带有硬重置子代码的BGP STOP通知消息，该功能可能会失效。如果使用硬重置，则执行完整会话重置。
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.
本文件中的关键词“必须”、“不得”、“必需”、“应”、“不应”、“建议”、“不建议”、“可”和“可选”在所有大写字母出现时（如图所示）应按照BCP 14[RFC2119][RFC8174]所述进行解释。
The BGP Graceful Restart Capability is augmented to signal the Graceful Restart support for BGP NOTIFICATION messages. The Restart Flags field is augmented as follows (following the diagram in Section 3 of [RFC4724]).
BGP优雅重启功能得到增强，以表示对BGP通知消息的优雅重启支持。重新启动标志字段扩充如下（遵循[RFC4724]第3节中的图表）。
Restart Flags:
重新启动标志：
This field contains bit flags relating to restart.
此字段包含与重新启动相关的位标志。
0 1 2 3
+-+-+-+-+
|R|N| |
+-+-+-+-+
0 1 2 3
+-+-+-+-+
|R|N| |
+-+-+-+-+
The most significant bit is defined in [RFC4724] as the Restart State ("R") bit.
最高有效位在[RFC4724]中定义为重启状态（“R”）位。
The second most significant bit is defined in this document as the Graceful Notification ("N") bit. It is used to indicate Graceful Restart support for BGP NOTIFICATION messages. A BGP speaker indicates support for the procedures in this document by advertising a Graceful Restart Capability with its "N" bit set (value 1).
第二个最高有效位在本文档中定义为优雅通知（“N”）位。它用于指示对BGP通知消息的正常重启支持。BGP扬声器通过其“N”位集（值1）宣传优雅的重启功能，表示支持本文档中的程序。
If a BGP speaker that previously advertised a given set of Graceful Restart parameters opens a new session with a different set of parameters, these new parameters apply once the session has transitioned into ESTABLISHED state.
如果先前播发一组给定的优雅重启参数的BGP扬声器使用另一组参数打开一个新会话，则一旦会话转换为已建立状态，这些新参数就会应用。
This document defines a new subcode for BGP Cease NOTIFICATION messages, called the Hard Reset subcode. The value of this subcode is discussed in Section 8. In this document, a BGP Cease NOTIFICATION message with the Hard Reset subcode is referred to as a "Hard Reset message" or simply as a "Hard Reset".
本文档为BGP停止通知消息定义了一个新的子代码，称为硬重置子代码。第8节讨论了此子代码的值。在本文档中，带有硬重置子代码的BGP停止通知消息称为“硬重置消息”或简称为“硬重置”。
When the "N" bit has been exchanged by two peers, NOTIFICATION messages other than Hard Reset messages are referred to as "Graceful", since such messages invoke Graceful Restart semantics.
当两个对等方交换了“N”位时，硬重置消息以外的通知消息称为“优雅”，因为此类消息调用优雅重启语义。
When the "N" bit has been exchanged, a Hard Reset message is used to indicate to the peer that the session is to be fully terminated.
交换“N”位后，将使用硬重置消息向对等方指示会话将完全终止。
When sending a Hard Reset, the data portion of the NOTIFICATION message is encoded as follows:
发送硬复位时，通知消息的数据部分编码如下：
+--------+--------+--------
| ErrCode| Subcode| Data
+--------+--------+--------
+--------+--------+--------
| ErrCode| Subcode| Data
+--------+--------+--------
ErrCode is a BGP Error Code (as documented in the IANA "BGP Error (Notification) Codes" registry) that indicates the reason for the Hard Reset. Subcode is a BGP Error Subcode (as documented in the IANA "BGP Error Subcodes" registry) as appropriate for the ErrCode. Similarly, Data is as appropriate for the ErrCode and Subcode. In short, the Hard Reset encapsulates another NOTIFICATION message in its data portion.
ErrCode是一个BGP错误代码（如IANA“BGP错误（通知）代码”注册表中所述），用于指示硬重置的原因。子代码是适用于错误代码的BGP错误子代码（如IANA“BGP错误子代码”注册表中所述）。同样，数据也适用于错误代码和子代码。简而言之，硬重置在其数据部分封装了另一条通知消息。
Whenever a BGP speaker receives a Hard Reset, the speaker MUST terminate the BGP session following the standard procedures in [RFC4271].
每当BGP扬声器接收到硬复位时，扬声器必须按照[RFC4271]中的标准程序终止BGP会话。
A BGP speaker that is willing to receive and send BGP NOTIFICATION messages according to the procedures of this document MUST advertise the "N" bit using the Graceful Restart Capability as defined in [RFC4724].
愿意根据本文件程序接收和发送BGP通知消息的BGP扬声器必须使用[RFC4724]中定义的优雅重启功能公布“N”位。
When such a BGP speaker has received the "N" bit from its peer, and receives from that peer a BGP NOTIFICATION message other than a Hard Reset, it MUST follow the rules for the Receiving Speaker mentioned in Section 4.1. The BGP speaker generating the BGP NOTIFICATION message MUST also follow the rules for the Receiving Speaker.
当此类BGP扬声器从其对等方接收到“N”位，并从该对等方接收到除硬复位以外的BGP通知消息时，必须遵守第4.1节中提及的接收扬声器规则。生成BGP通知消息的BGP扬声器也必须遵守接收扬声器的规则。
When a BGP speaker resets its session due to a HOLDTIME expiry, it should generate the relevant BGP NOTIFICATION message as mentioned in [RFC4271] but subsequently MUST follow the rules for the Receiving Speaker mentioned in Section 4.1.
当BGP演讲者由于等待时间到期而重置其会话时，它应生成[RFC4271]中提到的相关BGP通知消息，但随后必须遵循第4.1节中提到的接收演讲者规则。
A BGP speaker SHOULD NOT send a Hard Reset to a peer from which it has not received the "N" bit. We note, however, that if it did so, the effect would be as desired in any case because, according to [RFC4271] and [RFC4724], any NOTIFICATION message, whether recognized or not, results in a session reset. Thus, the only negative effect to be expected from sending the Hard Reset to a peer that hasn't advertised compliance to this specification would be that the peer would be unable to properly log the associated information.
BGP扬声器不应向未接收到“N”位的对等方发送硬复位。然而，我们注意到，如果它这样做了，在任何情况下效果都会如预期的那样，因为根据[RFC4271]和[RFC4724]，任何通知消息，无论是否被识别，都会导致会话重置。因此，将硬重置发送给未公布遵守本规范的对等方的唯一负面影响是，该对等方将无法正确记录相关信息。
Once the session is re-established, both BGP speakers SHOULD set their Forwarding State bit to 1. If the Forwarding State bit is not set, then, according to the procedures in Section 4.2 of [RFC4724], the relevant routes will be flushed, defeating the goals of this specification.
一旦会话重新建立，两个BGP扬声器应将其转发状态位设置为1。如果未设置转发状态位，则根据[RFC4724]第4.2节中的程序，相关路由将被刷新，不符合本规范的目标。
Section 4.2 of [RFC4724] defines rules for the Receiving Speaker. This document modifies those rules as follows:
[RFC4724]第4.2节定义了接收扬声器的规则。本文件对这些规则的修改如下：
The sentence "To deal with possible consecutive restarts, a route (from the peer) previously marked as stale MUST be deleted" only applies when the "N" bit has not been exchanged with the peer:
“为了处理可能的连续重启，必须删除先前标记为过时的路由（来自对等方）”，这句话仅在“N”位未与对等方交换时适用：
OLD: When the Receiving Speaker detects termination of the TCP session for a BGP session with a peer that has advertised the Graceful Restart Capability, it MUST retain the routes received from the peer for all the address families that were previously received in the Graceful Restart Capability and MUST mark them as stale routing information. To deal with possible consecutive restarts, a route (from the peer) previously marked as stale MUST be deleted. The router MUST NOT differentiate between stale and other routing information during forwarding.
旧：当接收扬声器检测到BGP会话的TCP会话终止，且该会话的对等方已通告优雅重启功能时，它必须保留从该对等方接收的所有先前在优雅重启功能中接收到的地址族的路由，并且必须将其标记为陈旧路由信息。要处理可能的连续重新启动，必须删除以前标记为过时的路由（来自对等路由）。在转发过程中，路由器不得区分过时和其他路由信息。
NEW: When the Receiving Speaker detects termination of the TCP session for a BGP session with a peer that has advertised the Graceful Restart Capability, it MUST retain the routes received from the peer for all the address families that were previously received in the Graceful Restart Capability and MUST mark them as stale routing information. The router MUST NOT differentiate between stale and other routing information during forwarding. If the "N" bit has not been exchanged with the peer, then to deal with possible consecutive restarts, a route (from the peer) previously marked as stale MUST be deleted.
新增：当接收扬声器检测到BGP会话的TCP会话终止，且对等方已通告正常重启功能时，它必须保留从对等方接收的所有先前在正常重启功能中接收到的地址族的路由，并且必须将其标记为陈旧的路由信息。在转发过程中，路由器不得区分过时和其他路由信息。如果尚未与对等方交换“N”位，则为了处理可能的连续重新启动，必须删除先前标记为过时的路由（来自对等方）。
The stale timer is given a formal name and made mandatory:
过时计时器具有正式名称，并被强制使用：
OLD: To put an upper bound on the amount of time a router retains the stale routes, an implementation MAY support a (configurable) timer that imposes this upper bound.
旧的：为了给路由器保留过时路由的时间量设置一个上限，一个实现可以支持一个（可配置的）计时器来施加这个上限。
NEW: To put an upper bound on the amount of time a router retains the stale routes, an implementation MUST support a (configurable) timer, called the "stale timer", that imposes this upper bound. A suggested default value for the stale timer is 180 seconds. An implementation MAY provide the option to disable the timer (i.e., to provide an infinite retention time) but MUST NOT do so by default.
新增：为了给路由器保留过时路由的时间量设置上限，实现必须支持一个（可配置的）计时器，称为“过时计时器”，该计时器施加了这个上限。陈旧计时器的建议默认值为180秒。实现可以提供禁用计时器的选项（即，提供无限保留时间），但默认情况下不能这样做。
Although when to send a Hard Reset is an implementation-specific decision, we offer some advice. Many Cease NOTIFICATION subcodes represent permanent or long-term, rather than transient, session termination. Because of this, it's appropriate to use Hard Reset with them. As of publication of this document, subcodes 1-9 have been defined for Cease. The following table lists each of these subcodes along with suggested behavior.
虽然何时发送硬重置是一个具体实现的决定，但我们提供了一些建议。许多停止通知子代码表示永久或长期（而非暂时）会话终止。因此，对它们使用硬重置是合适的。截至本文件发布时，已为STORE定义了子代码1-9。下表列出了每个子代码以及建议的行为。
+-------+------------------------------------+----------------------+
| Value | Name | Suggested Behavior |
+-------+------------------------------------+----------------------+
| 1 | Maximum Number of Prefixes Reached | Hard Reset |
| 2 | Administrative Shutdown | Hard Reset |
| 3 | Peer De-configured | Hard Reset |
| 4 | Administrative Reset | Provide user control |
| 5 | Connection Rejected | Graceful Cease |
| 6 | Other Configuration Change | Graceful Cease |
| 7 | Connection Collision Resolution | Graceful Cease |
| 8 | Out of Resources | Graceful Cease |
| 9 | Hard Reset | Hard Reset |
+-------+------------------------------------+----------------------+
+-------+------------------------------------+----------------------+
| Value | Name | Suggested Behavior |
+-------+------------------------------------+----------------------+
| 1 | Maximum Number of Prefixes Reached | Hard Reset |
| 2 | Administrative Shutdown | Hard Reset |
| 3 | Peer De-configured | Hard Reset |
| 4 | Administrative Reset | Provide user control |
| 5 | Connection Rejected | Graceful Cease |
| 6 | Other Configuration Change | Graceful Cease |
| 7 | Connection Collision Resolution | Graceful Cease |
| 8 | Out of Resources | Graceful Cease |
| 9 | Hard Reset | Hard Reset |
+-------+------------------------------------+----------------------+
These suggestions are only that -- suggestions, not requirements. It's the nature of BGP implementations that the mapping of internal states to BGP NOTIFICATION codes and subcodes is not always perfect. The guiding principle for the implementor should be that if there is no realistic hope that forwarding can continue or that the session will be re-established within the deadline, Hard Reset should be used.
这些建议只是建议，不是要求。BGP实现的本质是，内部状态到BGP通知代码和子代码的映射并不总是完美的。实施者的指导原则应该是，如果没有继续转发或在截止日期内重新建立会话的实际希望，则应使用硬重置。
For all NOTIFICATION codes other than Cease, use of Hard Reset does not appear to be indicated.
对于除STOP以外的所有通知代码，似乎未指示使用硬复位。
"BGP Administrative Shutdown Communication" [RFC8203] specifies use of the data portion of the Administrative Shutdown or Administrative Reset subcodes to convey a short message. When [RFC8203] is used in conjunction with Hard Reset, the subcode of the outermost Cease MUST be Hard Reset, with the Administrative Shutdown or Administrative Reset subcodes encapsulated within. The encapsulated message MUST subsequently be processed according to [RFC8203].
“BGP管理关机通信”[RFC8203]指定使用管理关机或管理重置子代码的数据部分来传送短消息。当[RFC8203]与硬复位一起使用时，最外层STORE的子代码必须硬复位，管理关机或管理复位子代码封装在其中。随后必须根据[RFC8203]处理封装的消息。
When reporting a Hard Reset to network management, the error code and subcode reported MUST be Cease and Hard Reset, respectively. If the network management layer in use permits it, the information carried in the Data portion SHOULD be reported as well.
向网络管理报告硬重置时，报告的错误代码和子代码必须分别停止和硬重置。如果使用中的网络管理层允许，则还应报告数据部分中携带的信息。
Note that long (or infinite) retention time may cause operational issues and should be enabled with care.
请注意，长（或无限）保留时间可能会导致操作问题，应小心启用。
IANA has assigned subcode 9 ("Hard Reset") in the "BGP Cease NOTIFICATION message subcodes" registry.
IANA已在“BGP停止通知消息子代码”注册表中分配子代码9（“硬重置”）。
IANA has created a sub-registry called "BGP Graceful Restart Flags" under the "Border Gateway Protocol (BGP) Parameters" registry. The registration procedure is Standards Action [RFC8126]; this document and [RFC4724] are listed as references. The initial values are as follows:
IANA在“边界网关协议（BGP）参数”注册表下创建了一个名为“BGP优雅重启标志”的子注册表。注册程序为标准行动[RFC8126]；本文件和[RFC4724]列为参考文件。初始值如下所示：
+--------------+---------------+------------+-----------+
| Bit Position | Name | Short Name | Reference |
+--------------+---------------+------------+-----------+
| 0 | Restart State | R | RFC 4724 |
| 1 | Notification | N | RFC 8538 |
| 2-3 | Unassigned | | |
+--------------+---------------+------------+-----------+
+--------------+---------------+------------+-----------+
| Bit Position | Name | Short Name | Reference |
+--------------+---------------+------------+-----------+
| 0 | Restart State | R | RFC 4724 |
| 1 | Notification | N | RFC 8538 |
| 2-3 | Unassigned | | |
+--------------+---------------+------------+-----------+
IANA has created a sub-registry called "BGP Graceful Restart Flags for Address Family" under the "Border Gateway Protocol (BGP) Parameters" registry. The registration procedure is Standards Action; this document and [RFC4724] are listed as references. The initial values are as follows:
IANA在“边界网关协议（BGP）参数”注册表下创建了一个名为“BGP地址族优雅重启标志”的子注册表。注册程序是标准行动；本文件和[RFC4724]列为参考文件。初始值如下所示：
+--------------+------------------+------------+-----------+
| Bit Position | Name | Short Name | Reference |
+--------------+------------------+------------+-----------+
| 0 | Forwarding State | F | RFC 4724 |
| 1-7 | Unassigned | | |
+--------------+------------------+------------+-----------+
+--------------+------------------+------------+-----------+
| Bit Position | Name | Short Name | Reference |
+--------------+------------------+------------+-----------+
| 0 | Forwarding State | F | RFC 4724 |
| 1-7 | Unassigned | | |
+--------------+------------------+------------+-----------+
This specification doesn't change the basic security model inherent in [RFC4724], with the exception that the protection against repeated resets is relaxed. To mitigate the consequent risk that an attacker could use repeated session resets to prevent stale routes from ever being deleted, we make the stale timer mandatory (in practice, it is already ubiquitous). To the extent [RFC4724] might be said to help defend against denials of service by making the control plane more resilient, this extension may modestly increase that resilience; however, there are enough confounding and deployment-specific factors that no general claims can be made.
本规范没有改变[RFC4724]中固有的基本安全模型，但放松了对重复重置的保护。为了降低攻击者可能使用重复会话重置来防止过时路由被删除的风险，我们强制使用过时计时器（实际上，它已经无处不在）。在某种程度上，[RFC4724]可以说通过使控制飞机更具弹性来帮助防御拒绝服务，这种扩展可以适度地增加这种弹性；然而，有足够多的混淆和部署特定因素，因此无法作出一般性声明。
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <https://www.rfc-editor.org/info/rfc2119>.
[RFC2119]Bradner，S.，“RFC中用于表示需求水平的关键词”，BCP 14，RFC 2119，DOI 10.17487/RFC2119，1997年3月<https://www.rfc-editor.org/info/rfc2119>.
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A Border Gateway Protocol 4 (BGP-4)", RFC 4271, DOI 10.17487/RFC4271, January 2006, <https://www.rfc-editor.org/info/rfc4271>.
[RFC4271]Rekhter，Y.，Ed.，Li，T.，Ed.，和S.Hares，Ed.，“边境网关协议4（BGP-4）”，RFC 4271，DOI 10.17487/RFC4271，2006年1月<https://www.rfc-editor.org/info/rfc4271>.
[RFC4724] Sangli, S., Chen, E., Fernando, R., Scudder, J., and Y. Rekhter, "Graceful Restart Mechanism for BGP", RFC 4724, DOI 10.17487/RFC4724, January 2007, <https://www.rfc-editor.org/info/rfc4724>.
[RFC4724]Sangli，S.，Chen，E.，Fernando，R.，Scudder，J.，和Y.Rekhter，“BGP的优雅重启机制”，RFC 4724，DOI 10.17487/RFC4724，2007年1月<https://www.rfc-editor.org/info/rfc4724>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8174]Leiba，B.，“RFC 2119关键词中大写与小写的歧义”，BCP 14，RFC 8174，DOI 10.17487/RFC8174，2017年5月<https://www.rfc-editor.org/info/rfc8174>.
[RFC8203] Snijders, J., Heitz, J., and J. Scudder, "BGP Administrative Shutdown Communication", RFC 8203, DOI 10.17487/RFC8203, July 2017, <https://www.rfc-editor.org/info/rfc8203>.
[RFC8203]Snijders，J.，Heitz，J.，和J.Scudder，“BGP管理关闭通信”，RFC 8203，DOI 10.17487/RFC8203，2017年7月<https://www.rfc-editor.org/info/rfc8203>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 8126, DOI 10.17487/RFC8126, June 2017, <https://www.rfc-editor.org/info/rfc8126>.
[RFC8126]Cotton，M.，Leiba，B.，和T.Narten，“在RFC中编写IANA考虑事项部分的指南”，BCP 26，RFC 8126，DOI 10.17487/RFC8126，2017年6月<https://www.rfc-editor.org/info/rfc8126>.
Acknowledgements
致谢
The authors would like to thank Jim Uttaro for the suggestion. The authors would also like to thank Emmanuel Baccelli, Bruno Decraene, Chris Hall, Warren Kumari, Paul Mattes, Robert Raszuk, and Alvaro Retana for their reviews and comments.
作者要感谢Jim Uttaro的建议。作者还要感谢伊曼纽尔·巴切利、布鲁诺·德雷恩、克里斯·霍尔、沃伦·库马里、保罗·马特斯、罗伯特·拉祖克和阿尔瓦罗·雷塔纳的评论和评论。
Authors' Addresses
作者地址
Keyur Patel Arrcus
颈髌韧带
Email: keyur@arrcus.com
Email: keyur@arrcus.com
Rex Fernando Cisco Systems 170 W. Tasman Drive San Jose, CA 95134 United States of America
美国加利福尼亚州圣何塞塔斯曼大道西170号，邮编95134
Email: rex@cisco.com
Email: rex@cisco.com
John Scudder Juniper Networks 1194 N. Mathilda Ave Sunnyvale, CA 94089 United States of America
John Scudder Juniper Networks 1194 N.Mathilda Ave Sunnyvale，加利福尼亚州，美利坚合众国，邮编94089
Email: jgs@juniper.net
Email: jgs@juniper.net
Jeff Haas Juniper Networks 1194 N. Mathilda Ave Sunnyvale, CA 94089 United States of America
Jeff Haas Juniper Networks 1194 N.Mathilda Ave Sunnyvale，加利福尼亚州，美国94089
Email: jhaas@juniper.net
Email: jhaas@juniper.net