BGP BFD Strict-Mode
draft-ietf-idr-bgp-bfd-strict-mode-02
IDR Workgroup M. Zheng
Internet-Draft Individual Contributor
Intended status: Standards Track A. Lindem
Expires: May 7, 2020 Cisco Systems
J. Haas
Juniper Networks, Inc.
A. Fu
Bloomberg L.P.
November 4, 2019
BGP BFD Strict-Mode
draft-ietf-idr-bgp-bfd-strict-mode-02
Abstract
This document specifies extensions to RFC4271 BGP-4 that enable a BGP
speaker to negotiate additional Bidirectional Forwarding Detection
(BFD) extensions using a BGP capability. This BFD capability enables
a BGP speaker to prevent a BGP session from being established until a
BFD session is established. It is referred to as BGP BFD "strict-
mode". BGP BFD strict-mode will be supported when both the local
speaker and its remote peer are BFD strict-mode capable.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. BFD Strict-Mode Capability . . . . . . . . . . . . . . . . . 3
4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 3
5. Manageability Considerations . . . . . . . . . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . 4
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
8. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 4
9. Normative References . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
Bidirectional Forwarding Detection BFD [RFC5882] enables routers to
monitor data plane connectivity and to detect faults in the
bidirectional forwarding path between them. This capability is
leveraged by routing protocols such as BGP [RFC4271] to rapidly react
to topology changes in the face of path failures.
The BFD interaction with BGP is specified in Section 10.2 of
[RFC5882]. When BFD is enabled for a BGP neighbor, faults in the
bidirectional forwarding detected by BFD result in session
termination. It is possible in some failure scenarios for the
network to be in a state such that a BGP session may be established
but a BFD session cannot be established. In some other scenarios, it
may be possible to establish a BGP session, but a degraded or poor-
quality link may result in the corresponding BFD session going up and
down frequently.
To avoid situations which result in routing churn and to minimize the
impact of network interruptions, it will be beneficial to disallow
BGP to establish a session until BFD session is successfully
established and has stabilized. We refer to this mode of operation
as BGP BFD "strict-mode". However, always using "strict-mode" would
preclude BGP operation in an environment where not all routers
support BFD strict-mode or have BFD enabled. This document defines
BGP "strict-mode" operation as preventing BGP session establishment
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