Network Working Group E. Chen
Request for Comments: 2918 Redback Networks
Category: Standards Track September 2000
Network Working Group E. Chen
Request for Comments: 2918 Redback Networks
Category: Standards Track September 2000
Route Refresh Capability for BGP-4
BGP-4的路由刷新能力
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 (2000). All Rights Reserved.
版权所有（C）互联网协会（2000年）。版权所有。
Abstract
摘要
This document defines a new Border Gateway Protocol (BGP) capability termed 'Route Refresh Capability', which would allow the dynamic exchange of route refresh request between BGP speakers and subsequent re-advertisement of the respective Adj-RIB-Out. One possible application of this capability is to facilitate non-disruptive routing policy changes.
本文件定义了一种称为“路由刷新能力”的新边界网关协议（BGP）能力，该能力允许BGP扬声器之间动态交换路由刷新请求，并随后重新公布相应的Adj输出。此功能的一个可能应用是促进无中断路由策略更改。
Currently there does not exist a mechanism in BGP-4 [BGP-4] to dynamically request a re-advertisement of the Adj-RIB-Out from a BGP peer. When the inbound routing policy for a peer changes, all prefixes from that peer must be somehow made available and then re-examined against the new policy. To accomplish this, a commonly used approach, known as 'soft-reconfiguration', is to store an unmodified copy of all routes from that peer at all times, even though routing policies do not change frequently (typically no more than a couple times a day). Additional memory and CPU are required to maintain these routes.
目前，BGP-4[BGP-4]中不存在动态请求从BGP对等方重新公布Adj RIB的机制。当对等方的入站路由策略更改时，必须以某种方式使该对等方的所有前缀可用，然后根据新策略重新检查。为了实现这一点，一种常用的方法称为“软重新配置”，即始终存储来自该对等方的所有路由的未修改副本，即使路由策略不经常更改（通常一天不超过几次）。需要额外的内存和CPU来维护这些路由。
This document proposes an alternative solution that avoids the additional maintenance cost. More specifically, it defines a new BGP capability termed 'Route Refresh Capability', which would allow the dynamic exchange of route refresh request between BGP speakers and subsequent re-advertisement of the respective Adj-RIB-Out.
本文件提出了避免额外维护成本的替代解决方案。更具体地说，它定义了一种称为“路由刷新能力”的新BGP能力，该能力允许BGP扬声器之间动态交换路由刷新请求，并随后重新公布相应的Adj输出。
To advertise the Route Refresh Capability to a peer, a BGP speaker uses BGP Capabilities Advertisement [BGP-CAP]. This capability is advertised using the Capability code 2 and Capability length 0.
为了向对等方通告路由刷新功能，BGP扬声器使用BGP功能通告[BGP-CAP]。使用功能代码2和功能长度0公布此功能。
By advertising the Route Refresh Capability to a peer, a BGP speaker conveys to the peer that the speaker is capable of receiving and properly handling the ROUTE-REFRESH message (as defined in Section 3) from the peer.
通过向对等方公布路由刷新能力，BGP演讲者向对等方传达演讲者能够从对等方接收并正确处理路由刷新消息（如第3节所定义）。
The ROUTE-REFRESH message is a new BGP message type defined as follows:
ROUTE-REFRESH消息是一种新的BGP消息类型，定义如下：
Type: 5 - ROUTE-REFRESH
类型：5-路由刷新
Message Format: One <AFI, SAFI> encoded as
Message Format: One <AFI, SAFI> encoded as
0 7 15 23 31
+-------+-------+-------+-------+
| AFI | Res. | SAFI |
+-------+-------+-------+-------+
0 7 15 23 31
+-------+-------+-------+-------+
| AFI | Res. | SAFI |
+-------+-------+-------+-------+
The meaning, use and encoding of this <AFI, SAFI> field is the same as defined in [BGP-MP, sect. 7]. More specifically,
该<AFI，SAFI>字段的含义、用途和编码与[BGP-MP，第7节]中的定义相同。更具体地说，
AFI - Address Family Identifier (16 bit).
AFI-地址族标识符（16位）。
Res. - Reserved (8 bit) field. Should be set to 0 by the sender and ignored by the receiver.
Res.-保留（8位）字段。发送方应将设置为0，接收方应忽略。
SAFI - Subsequent Address Family Identifier (8 bit).
SAFI-后续地址系列标识符（8位）。
A BGP speaker that is willing to receive the ROUTE-REFRESH message from its peer should advertise the Route Refresh Capability to the peer using BGP Capabilities advertisement [BGP-CAP].
愿意从对等方接收路由刷新消息的BGP演讲者应使用BGP功能公告[BGP-CAP]向对等方公告路由刷新功能。
A BGP speaker may send a ROUTE-REFRESH message to its peer only if it has received the Route Refresh Capability from its peer. The <AFI, SAFI> carried in such a message should be one of the <AFI, SAFI> that the peer has advertised to the speaker at the session establishment time via capability advertisement.
BGP演讲者只有在从其对等方接收到路由刷新功能时，才可以向其对等方发送路由刷新消息。这样的消息中携带的<AFI，SAFI>应该是对等方在会话建立时通过能力广告向说话人广告的<AFI，SAFI>之一。
If a BGP speaker receives from its peer a ROUTE-REFRESH message with the <AFI, SAFI> that the speaker didn't advertise to the peer at the session establishment time via capability advertisement, the speaker shall ignore such a message. Otherwise, the BGP speaker shall re-advertise to that peer the Adj-RIB-Out of the <AFI, SAFI> carried in the message, based on its outbound route filtering policy.
如果BGP演讲者从其对等方收到一条路由刷新消息，该消息带有<AFI，SAFI>，表明演讲者在会话建立时没有通过能力通告向对等方通告，则演讲者应忽略该消息。否则，BGP演讲者应根据其出站路由过滤策略，将消息中携带的<AFI，SAFI>中的Adj RIB重新通告给该对等方。
This extension to BGP does not change the underlying security issues.
BGP的此扩展不会改变基础安全问题。
The concept of Route Refresh proposed is similar to the one used in IDRP.
提出的路由刷新概念与IDRP中使用的概念类似。
The author would like to thank Yakov Rekhter, Ravi Chandra, Srihari Ramachandra and Bruce Cole for their review and comments.
作者要感谢雅科夫·雷克特、拉维·钱德拉、斯利哈里·拉马钱德拉和布鲁斯·科尔的评论和评论。
[BGP-4] Rekhter, Y. and T. Li, "A Border Gateway Protocol 4 (BGP-4)", RFC 1771, March 1995.
[BGP-4]Rekhter，Y.和T.Li，“边境网关协议4（BGP-4）”，RFC 17711995年3月。
[BGP-MP] Bates, T., Chandra, R., Katz, D. and Y. Rekhter, "Multiprotocol Extensions for BGP-4", RFC 2858, June 2000.
[BGP-MP]Bates，T.，Chandra，R.，Katz，D.和Y.Rekhter，“BGP-4的多协议扩展”，RFC 28582000年6月。
[BGP-CAP] Chandra, R. and J. Scudder, "Capabilities Advertisement with BGP-4", RFC 2842, May 2000.
[BGP-CAP]Chandra，R.和J.Scudder，“BGP-4的能力广告”，RFC 2842，2000年5月。
Enke Chen Redback Networks Inc. 350 Holger Way San Jose, CA 95134
Enke Chen Redback Networks Inc.加利福尼亚州圣何塞霍尔格路350号，邮编95134
EMail: enke@redback.com
EMail: enke@redback.com
Copyright (C) The Internet Society (2000). All Rights Reserved.
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Acknowledgement
确认
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