SPF Back-off algorithm for link state IGPs
draft-ietf-rtgwg-backoff-algo-06
Network Working Group B. Decraene
Internet-Draft Orange
Intended status: Standards Track S. Litkowski
Expires: April 25, 2018 Orange Business Service
H. Gredler
RtBrick Inc
A. Lindem
Cisco Systems
P. Francois
C. Bowers
Juniper Networks, Inc.
October 22, 2017
SPF Back-off algorithm for link state IGPs
draft-ietf-rtgwg-backoff-algo-06
Abstract
This document defines a standard algorithm to back-off link-state IGP
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.
Requirements Language
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 [RFC2119].
Status of This Memo
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provisions of BCP 78 and BCP 79.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. High level goals . . . . . . . . . . . . . . . . . . . . . . 3
3. Definitions and parameters . . . . . . . . . . . . . . . . . 4
4. Principles of SPF delay algorithm . . . . . . . . . . . . . . 5
5. Specification of the SPF delay state machine . . . . . . . . 5
5.1. States . . . . . . . . . . . . . . . . . . . . . . . . . 5
5.2. States Transitions . . . . . . . . . . . . . . . . . . . 6
5.3. FSM Events . . . . . . . . . . . . . . . . . . . . . . . 7
6. Parameters . . . . . . . . . . . . . . . . . . . . . . . . . 9
7. Partial Deployment . . . . . . . . . . . . . . . . . . . . . 9
8. Impact on micro-loops . . . . . . . . . . . . . . . . . . . . 10
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
10. Security considerations . . . . . . . . . . . . . . . . . . . 10
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
12.1. Normative References . . . . . . . . . . . . . . . . . . 10
12.2. Informative References . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction
Link state IGPs, such as IS-IS [ISO10589-Second-Edition] and OSPF
[RFC2328], 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 at the same time.
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