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Saxena 7 Ciena Corporation 8 November 21, 2017 10 Reverse Defect Indicator for MPLS FM OAM 11 draft-ama-mpls-fm-rdi-00.txt 13 Abstract 15 This document describes extensions to the MPLS Fault Management 16 Operations, Administration, and Management (MPLS FM OAM) in RFC 6427 17 [RFC6427] to support Remote Defect Indication (RDI) functionality. 18 Specifically, it describes a mechanism for propagating MPLS FM OAM 19 messages to the upstream Label Edge Router (LER) in MPLS-TP [RFC5921] 20 bi-directional (associated and co-routed) Label Switched Paths 21 (LSPs). 23 Status of This Memo 25 This Internet-Draft is submitted in full conformance with the 26 provisions of BCP 78 and BCP 79. 28 Internet-Drafts are working documents of the Internet Engineering 29 Task Force (IETF). Note that other groups may also distribute 30 working documents as Internet-Drafts. The list of current Internet- 31 Drafts is at https://datatracker.ietf.org/drafts/current/. 33 Internet-Drafts are draft documents valid for a maximum of six months 34 and may be updated, replaced, or obsoleted by other documents at any 35 time. It is inappropriate to use Internet-Drafts as reference 36 material or to cite them other than as "work in progress." 38 This Internet-Draft will expire on May 25, 2018. 40 Copyright Notice 42 Copyright (c) 2017 IETF Trust and the persons identified as the 43 document authors. All rights reserved. 45 This document is subject to BCP 78 and the IETF Trust's Legal 46 Provisions Relating to IETF Documents 47 (https://trustee.ietf.org/license-info) in effect on the date of 48 publication of this document. Please review these documents 49 carefully, as they describe your rights and restrictions with respect 50 to this document. Code Components extracted from this document must 51 include Simplified BSD License text as described in Section 4.e of 52 the Trust Legal Provisions and are provided without warranty as 53 described in the Simplified BSD License. 55 Table of Contents 57 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 58 2. Reverse Defect Indicator (RDI) . . . . . . . . . . . . . . . 2 59 3. Theory of Operations . . . . . . . . . . . . . . . . . . . . 3 60 3.1. RDI Operation in Associated Bidirectional LSPs . . . . . 3 61 3.2. RDI Operation in Co-routed Bidirectional LSPs . . . . . . 4 62 4. IANA Requirements . . . . . . . . . . . . . . . . . . . . . . 4 63 5. Security Consideration . . . . . . . . . . . . . . . . . . . 4 64 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 65 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 66 7.1. Normative References . . . . . . . . . . . . . . . . . . 4 67 7.2. Informative References . . . . . . . . . . . . . . . . . 4 68 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 70 1. Introduction 72 The MPLS Fault Management Operations, Administration, and Management 73 (MPLS FM OAM) in RFC 6427 [RFC6427] describes a method to identify 74 faults in MPLS transport networks, and a protocol to notify the 75 upstream Label Edge Router (LER). However, in the case of MPLS-TP 76 [RFC5921] bi-directional Label Switched Paths (LSPs), the fault must 77 be coordinated on both, the upstream LER and the downstream LER 78 (which is the upstream LER for the reverse path). 80 In typical scenario, the Bidirectional Forwarding Detection (BFD) 81 protocol, as described in RFC 5880 [RFC5880], detects the fault 82 signaled by MPLS FM OAM on the upstream LER and propagates the fault 83 on the reverse LSP to the other MPLS-TP LSP LER. This allows the two 84 MPLS-TP LERs to coordinate failover to backup LSPs. 86 This document proposes a mechanism to achieve MPLS FM OAM fault 87 propagation on the MPLS-TP reverse LSP using a Reverse Defect 88 Indicator (RDI) MPLS FM OAM message. This allows fast fault 89 coordination between the bidirectional LSP end-points when the use of 90 BFD is not feasible. 92 2. Reverse Defect Indicator (RDI) 94 The functionality proposed for MPLS FM OAM RDI is achieved by adding 95 a RDI-flag in the MPLS Fault OAM message . 97 +-+-+-+-+-+---+-+-+ 98 |Reserved |RDI|L|R| 99 +-+-+-+-+-+---+-+-+ 101 Figure 1: RDI-Flag in MPLS FM OAM Flags 103 where: 105 L-Flag and R-Flag are as defined in RFC 6427 [RFC6427]. 107 RDI-Flag: Reverse Defect Indication Flag. The RDI-Flag is clear in 108 the common MPLS FM OAM messages as defined in RFC 6427 [RFC6427]. 109 The RDI-Flag is set to indicate that the message is MPLS FM OAM RDI. 111 3. Theory of Operations 113 3.1. RDI Operation in Associated Bidirectional LSPs 115 ------------------> 116 Forward LSP 118 +-------+ +-------+ 119 +--> | LSR-1 | --X---> | LSR-2 | --+ 120 | +-------+ Fault +-------+ AIS/LKR 121 | | 122 +-------+ --+ +--> +-------+ 123 | LER-A | +-------+ | LER-B | 124 +-------+ <------RDI----- | LSR-3 | <------RDI----- +-------+ 125 +-------+ 127 Reverse LSP 128 <------------------ 130 Figure 2: RDI Operation in Associated Bidirectional LSP 132 Figure 1 depicts an associated bidirectional LSP with: 134 Forward LSP (LER-A, LSR-1, LSR-2, LER-B) 136 Reverse LSP (LER-B, LSR-3, LER-A) 138 Scenario 1, Fault on LER-A: LSR-1 will detect a fault on the server 139 sub-layer and generate AIS/LKR message on the upstream link for 140 Forward LSP (towards LSR-2). LSR-2 will process the message and 141 forward it, unaltered, upstream to LER-B. LER-B will process the 142 message, set the RDI-Flag and forward it on the associated Reverse 143 LSP. Because the RDI-Flag is set, LSR-3 does not need to process the 144 message as the fault is not on the Reverse LSP and forwards it, 145 unaltered, towards LER-A. LER-A, if it receives the message (the 146 fault may only be on the forward LSP on LER-A) processes the message 147 and discard it (RDI-Flag set received on Reverse LSP indicates the 148 fault is on the Forward LSP, and vice-versa). When the fault clears, 149 LSR-1 will issue new set of AIS/LKR messages to clear the previous 150 fault condition. This message is also propagated using the previous 151 RDI logic to coordinate fault clear on the Reverse LSP. 153 Scenario 2, Link fault or LSR fault on Forward LSP: Same logic as 154 fault on LER-A. 156 3.2. RDI Operation in Co-routed Bidirectional LSPs 158 RDI is not a required mechanism in co-routed bidirectional LSPs as 159 MPLS LSx on either direction of the fault will generate MPLS FM OAM 160 messages and the fault is propagated to both LERs. 162 4. IANA Requirements 164 None. 166 5. Security Consideration 168 No additional security impact because of addition of RDI-Flag in MPLS 169 FM OAM messages. 171 6. Acknowledgements 173 7. References 175 7.1. Normative References 177 [RFC5921] Bocci, M., Ed., Bryant, S., Ed., Frost, D., Ed., Levrau, 178 L., and L. Berger, "A Framework for MPLS in Transport 179 Networks", RFC 5921, DOI 10.17487/RFC5921, July 2010, 180 . 182 [RFC6427] Swallow, G., Ed., Fulignoli, A., Ed., Vigoureux, M., Ed., 183 Boutros, S., and D. Ward, "MPLS Fault Management 184 Operations, Administration, and Maintenance (OAM)", 185 RFC 6427, DOI 10.17487/RFC6427, November 2011, 186 . 188 7.2. Informative References 190 [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection 191 (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010, 192 . 194 Authors' Addresses 196 Ashesh Mishra 197 O3b Networks 198 USA 200 Email: mishra.ashesh@outlook.com 202 Mahesh Jethanandani 203 USA 205 Email: mjethanandani@gmail.com 207 Ankur Saxena 208 Ciena Corporation 209 3939 North 1st Street 210 San Jose, CA 95134 211 USA 213 Email: ankurpsaxena@gmail.com