< draft-ietf-mpls-bfd-directed-16.txt   draft-ietf-mpls-bfd-directed-17.txt >
MPLS Working Group G. Mirsky MPLS Working Group G. Mirsky
Internet-Draft ZTE Internet-Draft ZTE
Intended status: Standards Track J. Tantsura Intended status: Standards Track J. Tantsura
Expires: August 6, 2021 Juniper Networks Expires: August 20, 2021 Juniper Networks
I. Varlashkin I. Varlashkin
Google Google
M. Chen M. Chen
Huawei Huawei
February 2, 2021 February 16, 2021
Bidirectional Forwarding Detection (BFD) Directed Return Path for MPLS Bidirectional Forwarding Detection (BFD) Directed Return Path for MPLS
Label Switched Paths (LSPs) Label Switched Paths (LSPs)
draft-ietf-mpls-bfd-directed-16 draft-ietf-mpls-bfd-directed-17
Abstract Abstract
Bidirectional Forwarding Detection (BFD) is expected to be able to Bidirectional Forwarding Detection (BFD) is expected to be able to
monitor a wide variety of encapsulations of paths between systems. monitor a wide variety of encapsulations of paths between systems.
When a BFD session monitors an explicitly routed unidirectional path When a BFD session monitors an explicitly routed unidirectional path
there may be a need to direct egress BFD peer to use a specific path there may be a need to direct egress BFD peer to use a specific path
for the reverse direction of the BFD session. for the reverse direction of the BFD session.
Status of This Memo Status of This Memo
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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 August 6, 2021. This Internet-Draft will expire on August 20, 2021.
Copyright Notice Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the Copyright (c) 2021 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
1.1. Conventions used in this document . . . . . . . . . . . . 3 1.1. Conventions used in this document . . . . . . . . . . . . 3
1.1.1. Requirements Language . . . . . . . . . . . . . . . . 3 1.1.1. Requirements Language . . . . . . . . . . . . . . . . 3
2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3 2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3
3. Control of the Reverse BFD Path . . . . . . . . . . . . . . . 3 3. Control of the Reverse BFD Path . . . . . . . . . . . . . . . 3
3.1. BFD Reverse Path TLV . . . . . . . . . . . . . . . . . . 3 3.1. BFD Reverse Path TLV . . . . . . . . . . . . . . . . . . 3
3.2. Return Codes . . . . . . . . . . . . . . . . . . . . . . 5 3.2. Return Codes . . . . . . . . . . . . . . . . . . . . . . 5
4. Use Case Scenario . . . . . . . . . . . . . . . . . . . . . . 5 4. Use Case Scenario . . . . . . . . . . . . . . . . . . . . . . 5
5. Operational Considerations . . . . . . . . . . . . . . . . . 5 5. Operational Considerations . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6.1. BFD Reverse Path TLV . . . . . . . . . . . . . . . . . . 6 6.1. BFD Reverse Path TLV . . . . . . . . . . . . . . . . . . 6
6.2. Return Code . . . . . . . . . . . . . . . . . . . . . . . 7 6.2. Return Code . . . . . . . . . . . . . . . . . . . . . . . 7
7. Implementation Status . . . . . . . . . . . . . . . . . . . . 7 7. Implementation Status . . . . . . . . . . . . . . . . . . . . 7
8. Security Considerations . . . . . . . . . . . . . . . . . . . 8 8. Security Considerations . . . . . . . . . . . . . . . . . . . 8
9. Normative References . . . . . . . . . . . . . . . . . . . . 8 9. Normative References . . . . . . . . . . . . . . . . . . . . 8
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 9 Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction 1. Introduction
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If the egress LSR cannot find the path specified in the Reverse Path If the egress LSR cannot find the path specified in the Reverse Path
TLV it MUST send Echo Reply with the received BFD Discriminator TLV, TLV it MUST send Echo Reply with the received BFD Discriminator TLV,
Reverse Path TLV and set the Return Code to "Failed to establish the Reverse Path TLV and set the Return Code to "Failed to establish the
BFD session. The specified reverse path was not found" Section 3.2. BFD session. The specified reverse path was not found" Section 3.2.
An implementation MAY provide configuration options to define action An implementation MAY provide configuration options to define action
at the egress BFD peer. For example, if the egress LSR cannot find at the egress BFD peer. For example, if the egress LSR cannot find
the path specified in the Reverse Path TLV, it MAY establish the BFD the path specified in the Reverse Path TLV, it MAY establish the BFD
session over an IP network, as defined in [RFC5884]. session over an IP network, as defined in [RFC5884].
The BFD Reverse Path TLV MAY be used in the bootstrapping of a BFD
session process described in Section 6 [RFC5884]. A system that
supports this specification MUST support using the BFD Reverse Path
TLV after the BFD session has been established. If a system that
supports this specification receives an LSP Ping with the BFD
Discriminator TLV and no BFD Reverse Path TLV even though the reverse
path for the specified BFD session has been established according to
the previously received BFD Reverse Path TLV, the egress LSR MUST
transition to transmitting periodic BFD Control messages as defined
in Section 7 [RFC5884].
3.2. Return Codes 3.2. Return Codes
This document defines the following Return Codes for MPLS LSP Echo This document defines the following Return Codes for MPLS LSP Echo
Reply: Reply:
o "Inappropriate Target FEC Stack sub-TLV present", (TBD3). When o "Inappropriate Target FEC Stack sub-TLV present", (TBD3). When
multicast Target FEC Stack sub-TLV found in the received Echo multicast Target FEC Stack sub-TLV found in the received Echo
Request by the egress BFD peer, an Echo Reply with the return code Request by the egress BFD peer, an Echo Reply with the return code
set to "Inappropriate Target FEC Stack sub-TLV present" MUST be set to "Inappropriate Target FEC Stack sub-TLV present" MUST be
sent to the ingress BFD peer Section 3.1. sent to the ingress BFD peer Section 3.1.
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