draft-ietf-idr-bgp-bfd-strict-mode-01.txt   draft-ietf-idr-bgp-bfd-strict-mode-02.txt 
IDR Workgroup M. Zheng IDR Workgroup M. Zheng
Internet-Draft Individual Contributor Internet-Draft Individual Contributor
Intended status: Standards Track A. Lindem Intended status: Standards Track A. Lindem
Expires: May 5, 2020 Cisco Systems Expires: May 7, 2020 Cisco Systems
J. Haas J. Haas
Juniper Networks, Inc. Juniper Networks, Inc.
A. Fu A. Fu
Bloomberg L.P. Bloomberg L.P.
November 2, 2019 November 4, 2019
BGP BFD Strict-Mode BGP BFD Strict-Mode
draft-ietf-idr-bgp-bfd-strict-mode-01 draft-ietf-idr-bgp-bfd-strict-mode-02
Abstract Abstract
This document specifies extensions to RFC4271 BGP-4 that enable a BGP This document specifies extensions to RFC4271 BGP-4 that enable a BGP
speaker to negotiate additional Bidirectional Forwarding Detection speaker to negotiate additional Bidirectional Forwarding Detection
(BFD) extensions using a BGP capability. This BFD capability enables (BFD) extensions using a BGP capability. This BFD capability enables
a BGP speaker to prevent a BGP session from being established until a 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- BFD session is established. It is referred to as BGP BFD "strict-
mode". BGP BFD strict-mode will be supported when both the local mode". BGP BFD strict-mode will be supported when both the local
speaker and its remote peer are BFD strict-mode capable. speaker and its remote peer are BFD strict-mode capable.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 5, 2020. This Internet-Draft will expire on May 7, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3 2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. BFD Strict-Mode Capability . . . . . . . . . . . . . . . . . 3 3. BFD Strict-Mode Capability . . . . . . . . . . . . . . . . . 3
4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 3
5. Manageability Considerations . . . . . . . . . . . . . . . . 4 5. Manageability Considerations . . . . . . . . . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . 4 6. Security Considerations . . . . . . . . . . . . . . . . . . . 4
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
8. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 4 8. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 4
9. Normative References . . . . . . . . . . . . . . . . . . . . 4 9. Normative References . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction 1. Introduction
Bidirectional Forwarding Detection BFD [RFC5882] enables routers to Bidirectional Forwarding Detection BFD [RFC5882] enables routers to
monitor data plane connectivity and to detect faults in the monitor data plane connectivity and to detect faults in the
bidirectional forwarding path between them. This capability is bidirectional forwarding path between them. This capability is
leveraged by routing protocols such as BGP [RFC4271] to rapidly react leveraged by routing protocols such as BGP [RFC4271] to rapidly react
to topology changes in the face of path failures. to topology changes in the face of path failures.
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The BGP Strict-Mode Capability [RFC5492] will allow a BGP speaker's The BGP Strict-Mode Capability [RFC5492] will allow a BGP speaker's
to advertise this capability. The capability is defined as follows: to advertise this capability. The capability is defined as follows:
Capability code: TBD Capability code: TBD
Capability length: 0 octets Capability length: 0 octets
4. Operation 4. Operation
A BGP speaker which supports capabilities advertisement MUST include A BGP speaker which supports capabilities advertisement and has BFD
the BFD strict-mode capability. strict-mode enabled MUST include the BFD strict-mode capability.
A BGP speaker which supports the BFD Strict-Mode capability, examines A BGP speaker which supports the BFD Strict-Mode capability, examines
the list of capabilities present in the capabilities that the speaker the list of capabilities present in the capabilities that the speaker
receives from its peer. If both the local and remote BGP speakers receives from its peer. If both the local and remote BGP speakers
include the BFD strict-mode capability, the BGP finite state machine include the BFD strict-mode capability, the BGP finite state machine
does not transition to the Established state from OpenSent or does not transition to the Established state from OpenSent or
OpenConfirm state [RFC4271] until the BFD session is in the Up state OpenConfirm state [RFC4271] until the BFD session is in the Up state
(see below for AdminDown state). This means that a KEEPALIVE message (see below for AdminDown state). This means that a KEEPALIVE message
is not sent nor is the KeepaliveTimer set. is not sent nor is the KeepaliveTimer set.
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Once the BFD session has transitioned to the Up state, the BGP FSM Once the BFD session has transitioned to the Up state, the BGP FSM
may proceed to transition to the Established state from the OpenSent may proceed to transition to the Established state from the OpenSent
or OpenConfirm state appropriately. I.e. a KEEPALIVE message is or OpenConfirm state appropriately. I.e. a KEEPALIVE message is
sent, and the KeepaliveTimer is started. sent, and the KeepaliveTimer is started.
If either BGP peer has not advertised the BFD Strict-Mode Capability, If either BGP peer has not advertised the BFD Strict-Mode Capability,
then a BFD session WILL NOT be required for the BGP session to reach then a BFD session WILL NOT be required for the BGP session to reach
Established state. This does not preclude usage of BFD after BGP Established state. This does not preclude usage of BFD after BGP
session establishment [RFC5882]. session establishment [RFC5882].
If BFD is disabled for a BGP peer and the BGP session state is being
held in OpenSent or OpenConfirm state, then the BGP will close
session, and start a new TCP connect.
5. Manageability Considerations 5. Manageability Considerations
Auto-configuration is possible for the enabling BGP BFD Strict-Mode. Auto-configuration is possible for the enabling BGP BFD Strict-Mode.
However, the configuration automation is out of the scope of this However, the configuration automation is out of the scope of this
document. document.
A BGP NOTIFICATION message Subcode indicating BFD Hold timer A BGP NOTIFICATION message Subcode indicating BFD Hold timer
expiration may be required for network management. (To be discussed expiration may be required for network management. (To be discussed
in the next revision of this document.) in the next revision of this document.)
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