--- 1/draft-ietf-grow-bgp-gshut-12.txt 2017-12-14 09:13:41.053548290 -0800 +++ 2/draft-ietf-grow-bgp-gshut-13.txt 2017-12-14 09:13:41.077548861 -0800 @@ -1,25 +1,25 @@ Network Working Group P. Francois, Ed. Internet-Draft Individual Contributor -Intended status: Informational B. Decraene, Ed. -Expires: April 14, 2018 Orange +Intended status: Standards Track B. Decraene, Ed. +Expires: June 17, 2018 Orange C. Pelsser Strasbourg University K. Patel Arrcus, Inc. C. Filsfils Cisco Systems - October 11, 2017 + December 14, 2017 Graceful BGP session shutdown - draft-ietf-grow-bgp-gshut-12 + draft-ietf-grow-bgp-gshut-13 Abstract This draft standardizes a new well-known BGP community GRACEFUL_SHUTDOWN to signal the graceful shutdown of paths. This draft also describes operational procedures which use this community to reduce the amount of traffic lost when BGP peering sessions are about to be shut down deliberately, e.g. for planned maintenance. Status of This Memo @@ -30,21 +30,21 @@ Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - This Internet-Draft will expire on April 14, 2018. + This Internet-Draft will expire on June 17, 2018. Copyright Notice Copyright (c) 2017 IETF Trust and the persons identified as the document authors. All rights reserved. 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 @@ -58,34 +58,34 @@ 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Packet loss upon manual EBGP session shutdown . . . . . . . . 3 4. EBGP graceful shutdown procedure . . . . . . . . . . . . . . 4 4.1. Pre-configuration . . . . . . . . . . . . . . . . . . . . 4 4.2. Operations at maintenance time . . . . . . . . . . . . . 4 4.3. BGP implementation support for graceful shutdown . . . . 5 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . 5 - 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 5 - 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 8.1. Normative References . . . . . . . . . . . . . . . . . . 5 + 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6 + 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 + 8.1. Normative References . . . . . . . . . . . . . . . . . . 6 8.2. Informative References . . . . . . . . . . . . . . . . . 6 - Appendix A. Alternative techniques with limited applicability . 6 - A.1. Multi Exit Discriminator tweaking . . . . . . . . . . . . 6 + Appendix A. Alternative techniques with limited applicability . 7 + A.1. Multi Exit Discriminator tweaking . . . . . . . . . . . . 7 A.2. IGP distance Poisoning . . . . . . . . . . . . . . . . . 7 Appendix B. Configuration Examples . . . . . . . . . . . . . . . 7 B.1. Cisco IOS XR . . . . . . . . . . . . . . . . . . . . . . 7 B.2. BIRD . . . . . . . . . . . . . . . . . . . . . . . . . . 8 B.3. OpenBGPD . . . . . . . . . . . . . . . . . . . . . . . . 8 - Appendix C. Beyond EBGP graceful shutdown . . . . . . . . . . . 8 - C.1. IBGP graceful shutdown . . . . . . . . . . . . . . . . . 8 - C.2. EBGP session establishment . . . . . . . . . . . . . . . 8 + Appendix C. Beyond EBGP graceful shutdown . . . . . . . . . . . 9 + C.1. IBGP graceful shutdown . . . . . . . . . . . . . . . . . 9 + C.2. EBGP session establishment . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 1. Introduction Routing changes in BGP can be caused by planned maintenance operations. This document defines a well-known community [RFC1997], called GRACEFUL_SHUTDOWN, for the purpose of reducing the management overhead of gracefully shutting down BGP sessions. The well-known community allows implementers to provide an automated graceful shutdown mechanism that does not require any router reconfiguration @@ -105,23 +105,29 @@ avoid packet loss for outbound and inbound traffic flows initially forwarded along the peering link to be shut down. These procedures trigger, in both Autonomous Sytems (AS), rerouting to alternate paths if they exist within the AS, while allowing the use of the old path until alternate ones are learned. This ensures that routers always have a valid route available during the convergence process. The goal of the document is to meet the requirements described in [RFC6198] at best, without changing the BGP protocol. + Other maintenance cases, such as the shutdown of an IBGP session or + the establishement of an EBGP session, are out of scope of this + document. For information, they are briefly discussed in Appendix C. + 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 RFC 8174 [RFC8174]. + "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and + "OPTIONAL" in this document are to be interpreted as described in + [BCP14] [RFC2119] [RFC8174] when, and only when, they appear in all + capitals, as shown here. 2. Terminology graceful shutdown initiator: a router on which the session shutdown is performed for the maintenance. graceful shutdown receiver: a router that has a BGP session, to be shutdown, with the graceful shutdown initiator. 3. Packet loss upon manual EBGP session shutdown @@ -148,31 +154,37 @@ This section describes configurations and actions to be performed for the graceful shutdown of EBGP peering links. The goal of this procedure is to retain the paths to be shutdown between the peers, but with a lower LOCAL_PREF value, allowing the paths to remain in use while alternate paths are selected and propagated, rather than simply withdrawing the paths. The LOCAL_PREF value SHOULD be lower than any of the alternative paths. The RECOMMENDED value is 0. + Note that some alternative techniques with limited applicability are + discussed for information in Appendix A. + 4.1. Pre-configuration On each ASBR supporting the graceful shutdown receiver procedure, an inbound BGP route policy is applied on all EBGP sessions of the ASBR, that: o matches the GRACEFUL_SHUTDOWN community. o sets the LOCAL_PREF attribute of the paths tagged with the GRACEFUL_SHUTDOWN community to a low value. + For information purpose, example of configurations are provided in + Appendix B. + 4.2. Operations at maintenance time On the graceful shutdown initiator, at maintenance time, the operator: o applies an outbound BGP route policy on the EBGP session to be shutdown. This policy tags the paths propagated over the session with the GRACEFUL_SHUTDOWN community. This will trigger the BGP implementation to re-advertise all active routes previously advertised, and tag them with the GRACEFUL_SHUTDOWN community. @@ -230,20 +242,25 @@ comments. 8. References 8.1. Normative References [RFC1997] Chandra, R., Traina, P., and T. Li, "BGP Communities Attribute", RFC 1997, DOI 10.17487/RFC1997, August 1996, . + [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate + Requirement Levels", BCP 14, RFC 2119, + DOI 10.17487/RFC2119, March 1997, + . + [RFC6198] Decraene, B., Francois, P., Pelsser, C., Ahmad, Z., Elizondo Armengol, A., and T. Takeda, "Requirements for the Graceful Shutdown of BGP Sessions", RFC 6198, DOI 10.17487/RFC6198, April 2011, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, .