Shortest Path First (SPF) Back-Off Delay Algorithm for Link-State IGPs
RFC 8405
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RFC - Proposed Standard
(June 2018; No errata)
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Last updated |
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2018-12-19
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Replaces |
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draft-decraene-rtgwg-backoff-algo
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IETF
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plain text
pdf
html
bibtex
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Reviews |
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WG state
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Submitted to IESG for Publication
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Document shepherd |
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Uma Chunduri
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Shepherd write-up |
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Show
(last changed 2018-01-22)
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| IESG |
IESG state |
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RFC 8405 (Proposed Standard)
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Consensus Boilerplate |
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Yes
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Telechat date |
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Responsible AD |
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Alia Atlas
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Send notices to |
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Uma Chunduri <uma.chunduri@huawei.com>
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| IANA |
IANA review state |
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Version Changed - Review Needed
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IANA action state |
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No IANA Actions
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Internet Engineering Task Force (IETF) B. Decraene
Request for Comments: 8405 Orange
Category: Standards Track S. Litkowski
ISSN: 2070-1721 Orange Business Service
H. Gredler
RtBrick Inc.
A. Lindem
Cisco Systems
P. Francois
C. Bowers
Juniper Networks, Inc.
June 2018
Shortest Path First (SPF) Back-Off Delay Algorithm for Link-State IGPs
Abstract
This document defines a standard algorithm to temporarily postpone or
"back off" link-state IGP Shortest Path First (SPF) computations.
This reduces the computational load and churn on IGP nodes when
multiple temporally close network events trigger multiple SPF
computations.
Having one standard algorithm improves interoperability by reducing
the probability and/or duration of transient forwarding loops during
the IGP convergence when the IGP reacts to multiple temporally close
IGP events.
Status of This Memo
This is an Internet Standards Track document.
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.
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/rfc8405.
Decraene, et al. Standards Track [Page 1]
RFC 8405 SPF Back-Off Delay Algorithm June 2018
Copyright Notice
Copyright (c) 2018 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
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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. High-Level Goals . . . . . . . . . . . . . . . . . . . . . . 3
3. Definitions and Parameters . . . . . . . . . . . . . . . . . 4
4. Principles of the SPF Delay Algorithm . . . . . . . . . . . . 5
5. Specification of the SPF Delay State Machine . . . . . . . . 6
5.1. State Machine . . . . . . . . . . . . . . . . . . . . . . 6
5.2. States . . . . . . . . . . . . . . . . . . . . . . . . . 7
5.3. Timers . . . . . . . . . . . . . . . . . . . . . . . . . 7
5.4. FSM Events . . . . . . . . . . . . . . . . . . . . . . . 7
6. Parameters . . . . . . . . . . . . . . . . . . . . . . . . . 9
7. Partial Deployment . . . . . . . . . . . . . . . . . . . . . 10
8. Impact on Micro-loops . . . . . . . . . . . . . . . . . . . . 11
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
10. Security Considerations . . . . . . . . . . . . . . . . . . . 11
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
11.1. Normative References . . . . . . . . . . . . . . . . . . 11
11.2. Informative References . . . . . . . . . . . . . . . . . 11
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
Decraene, et al. Standards Track [Page 2]
RFC 8405 SPF Back-Off Delay Algorithm June 2018
1. Introduction
Link-state IGPs, such as IS-IS [ISO10589], OSPF [RFC2328], and OSPFv3
[RFC5340], perform distributed route computation on all routers in
the area/level. In order to have consistent routing tables across
the network, such distributed computation requires that all routers
have the same version of the network topology (Link-State Database
(LSDB)) and perform their computation essentially at the same time.
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