BGP-4的路由刷新功能(RFC2918)

1、RFC 2918 Route Refresh Capability for BGP-4 BGP-4（邊界網(wǎng)關(guān)協(xié)議）的路由刷新功能組織：中國互動出版網(wǎng)（/）RFC文檔中文翻譯計劃（/compters/emook/aboutemook.htm）E-mail：譯者：劉偉娜（superwinner，）譯文發(fā)布時間：2001-4-26版權(quán)：本中文翻譯文檔版權(quán)歸中國互動出版網(wǎng)所有?？梢杂糜诜巧虡I(yè)用途自由轉(zhuǎn)載，但必須保留本文檔的翻譯及版權(quán)

2、信息。Network Working Group E. ChenRequest for Comments: 2918 Redback NetworksCategory: Standards Track September 2000BGP-4（邊界網(wǎng)關(guān)協(xié)議）的路由刷新功能(RFC 2918 Route Refresh Capability for BGP-4)Status of this Memo This document specifies an Internet standards track protocol for the Internet community, and request

3、s 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.Copyright Notice Copyright (C) The Internet Society (2000). All Rig

4、hts Reserved.目錄摘要21.介紹22. 路由刷新功能23. 路由更新報文24. 操作36. 說明37. 參考文獻(xiàn)38. Authors Address49. Full Copyright Statement4摘要本文定義了BGP（邊界網(wǎng)關(guān)協(xié)議）的新功能“路由刷新功能“。它允許路由刷新請求在BGP揚聲器和相應(yīng)的廣告資源信息輸出模塊的后繼重新廣告(re-advertisment)之間進行動態(tài)交換。該功能的一種應(yīng)用是使無拆分的路由策略的更改更加容易。1. 介紹目前在BGP（邊界網(wǎng)關(guān)協(xié)議）4【BGP4】中還沒有提供從BGP同位體中動態(tài)申請廣告資源信息輸出模塊的重新廣告的機制。當(dāng)已有的一個同

5、位體的路由策略發(fā)生改變時，不知何故，必須訪問該同位體的所有前綴，然后再重新檢測新的路由策略。要完成這樣的功能，通常使用的是一種稱為“軟件重置”的策略也就是說要一直保存著該同位體的所有路由的備份，即使是路由策略并不經(jīng)常更改（通常情況下，一天也不會更改一兩次）。這樣的處理方法還需要額外的存儲器和CPU（中央處理器）來處理這些路由。本文提供了另外一種解決方案，這種方案可以避免額外處理的開銷。更明確的講，這種方法定義了一種新的BGP（邊界網(wǎng)關(guān)協(xié)議）功能，稱作“路由刷新功能”。該功能允許在BGP揚聲器和它們各自的廣告資源信息輸出塊的后繼廣播之間進行動態(tài)的路由交換。2. 路由刷新功能為了將路由刷新權(quán)限廣告

6、給它的同位體，BGP（邊界網(wǎng)關(guān)協(xié)議）的揚聲器要使用BGP（邊界網(wǎng)關(guān)協(xié)議）的權(quán)限廣告功能【BGP-CAP】。該權(quán)限使用權(quán)限代碼為2、權(quán)限長度為0的廣告功能進行廣告。通過將路由刷新權(quán)限廣告給它的同位體，BGP（邊界網(wǎng)關(guān)協(xié)議）的揚聲器給它的同位體傳遞該揚聲器已經(jīng)能夠接收并且恰當(dāng)?shù)奶幚韥碜杂谕惑w的路由刷新報文（報文的格式定義在本文的第3部分）了。3. 路由更新報文路由刷新報文是一種新的BGP（邊界網(wǎng)關(guān)協(xié)議）報文，該類報文的定義如下：類型 5 路由刷新報文格式：一個二元組，編碼如下： 0 7 15 23 31 +-+-+-+-+ | AFI | Res. | SAFI | +-+-+-+-+這個二元組

7、的意義和編碼方式與【BGP-MP, sect. 7】中定義的相同。詳細(xì)描述如下：AFI 地址組標(biāo)識符（16位）Res. 保留區(qū)域（8位）。方送方應(yīng)當(dāng)把它置為0，接收方應(yīng)當(dāng)忽略該域的信息。SAFI 后繼的地址組標(biāo)識符（8位）。4. 操作BGP（邊界網(wǎng)關(guān)協(xié)議）揚聲器是用來從它的同位體接收路由更新(ROUTE-REFRESH)報文的。它應(yīng)當(dāng)能夠使用BGP（邊界網(wǎng)關(guān)協(xié)議）的權(quán)限廣告【BGPCAP】功能將路由更新權(quán)限通知它的同位體。 BGP（邊界網(wǎng)關(guān)協(xié)議）揚聲器只有收到來自它的同位體的路由更新權(quán)限才有可能發(fā)送路由更新（ROUTE-REFRESH）報文。該報文中攜帶的應(yīng)當(dāng)是會話建立是它的同位體通過權(quán)限廣告

8、功能通知揚聲器的。 如果BGP（邊界網(wǎng)關(guān)協(xié)議）揚聲器從它的同位體那里收到了一個帶有的報文，但是，該報文并不是會話建立是通過權(quán)限廣告功能發(fā)送過來的；那么，BGP（邊界網(wǎng)關(guān)協(xié)議）揚聲器就會忽略該報文。否則，BGP(邊界網(wǎng)關(guān)協(xié)議)將會根據(jù)它的輸出路由過慮策略將帶有的Adj-RIB-Out報文重新廣播給它的同位體。 5. 安全因素對BGP（邊界網(wǎng)關(guān)協(xié)議）的擴展并沒有改變BGP（邊界網(wǎng)關(guān)協(xié)議）的安全因素。6. 說明路由刷新概念的提出類似于用于IDRP（域間路由協(xié)議）中的相應(yīng)概念。作者要特別感謝Yakov Rekhter,、Ravi Chandra、 Srihari Ramachandra 以及 Bruc

9、e Cole，他們?yōu)楸疚奶峁┝撕芎玫慕ㄗh和意見。7. 參考文獻(xiàn)BGP-4 Rekhter, Y. and T. Li, A Border Gateway Protocol 4 (BGP-4), RFC 1771, March 1995.BGP-MP Bates, T., Chandra, R., Katz, D. and Y. Rekhter, Multiprotocol Extensions for BGP-4, RFC 2858, June 2000.BGP-CAP Chandra, R. and J. Scudder, Capabilities Advertisement with BG

10、P-4, RFC 2842, May 2000.8. Authors Address Enke Chen Redback Networks Inc. 350 Holger Way San Jose, CA 95134 EMail: 9. Full Copyright Statement Copyright (C) The Internet Society (2000). All Rights Reserved. This document and translations of it may be copied and furnished to others, a

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