SPF Back-off algorithm for link state IGPs
draft-ietf-rtgwg-backoff-algo-06
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2017-11-29
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Uma Chunduri
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Uma Chunduri <uma.chunduri@huawei.com>
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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
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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."
Decraene, et al. Expires April 25, 2018 [Page 1]
Internet-Draft SPF back-off algorithm October 2017
This Internet-Draft will expire on April 25, 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
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
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.
Decraene, et al. Expires April 25, 2018 [Page 2]
Internet-Draft SPF back-off algorithm October 2017
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