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Mirsky 3 Internet-Draft ZTE Corp. 4 Intended status: Standards Track January 5, 2019 5 Expires: July 9, 2019 7 BFD for Multipoint Networks over Point-to-Multi-Point MPLS LSP 8 draft-mirsky-mpls-p2mp-bfd-06 10 Abstract 12 This document describes procedures for using Bidirectional Forwarding 13 Detection (BFD) for multipoint networks to detect data plane failures 14 in Multiprotocol Label Switching (MPLS) point-to-multipoint (p2mp) 15 Label Switched Paths (LSPs). It also describes the applicability of 16 LSP Ping, as in-band, and the control plane, as out-band, solutions 17 to bootstrap a BFD session in this environment. 19 Status of This Memo 21 This Internet-Draft is submitted in full conformance with the 22 provisions of BCP 78 and BCP 79. 24 Internet-Drafts are working documents of the Internet Engineering 25 Task Force (IETF). Note that other groups may also distribute 26 working documents as Internet-Drafts. The list of current Internet- 27 Drafts is at https://datatracker.ietf.org/drafts/current/. 29 Internet-Drafts are draft documents valid for a maximum of six months 30 and may be updated, replaced, or obsoleted by other documents at any 31 time. It is inappropriate to use Internet-Drafts as reference 32 material or to cite them other than as "work in progress." 34 This Internet-Draft will expire on July 9, 2019. 36 Copyright Notice 38 Copyright (c) 2019 IETF Trust and the persons identified as the 39 document authors. All rights reserved. 41 This document is subject to BCP 78 and the IETF Trust's Legal 42 Provisions Relating to IETF Documents 43 (https://trustee.ietf.org/license-info) in effect on the date of 44 publication of this document. Please review these documents 45 carefully, as they describe your rights and restrictions with respect 46 to this document. Code Components extracted from this document must 47 include Simplified BSD License text as described in Section 4.e of 48 the Trust Legal Provisions and are provided without warranty as 49 described in the Simplified BSD License. 51 Table of Contents 53 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 54 2. Conventions used in this document . . . . . . . . . . . . . . 2 55 2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 2 56 2.2. Requirements Language . . . . . . . . . . . . . . . . . . 3 57 3. Multipoint BFD Encapsulation . . . . . . . . . . . . . . . . 3 58 3.1. IP Encapsulation of Multipoint BFD . . . . . . . . . . . 3 59 3.2. Non-IP Encapsulation of Multipoint BFD . . . . . . . . . 4 60 4. Bootstrapping Multipoint BFD . . . . . . . . . . . . . . . . 4 61 4.1. LSP Ping . . . . . . . . . . . . . . . . . . . . . . . . 4 62 4.2. Control Plane . . . . . . . . . . . . . . . . . . . . . . 5 63 5. Security Considerations . . . . . . . . . . . . . . . . . . . 5 64 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 65 6.1. Source MEP ID IP Address Type . . . . . . . . . . . . . . 5 66 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 67 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 68 8.1. Normative References . . . . . . . . . . . . . . . . . . 6 69 8.2. Informative References . . . . . . . . . . . . . . . . . 7 70 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7 72 1. Introduction 74 [I-D.ietf-bfd-multipoint] defines a method of using Bidirectional 75 Detection (BFD) [RFC5880] to monitor and detect unicast failures 76 between the sender (head) and one or more receivers (tails) in 77 multipoint or multicast networks. This document describes procedures 78 for using such mode of BFD protocol to detect data plane failures in 79 Multiprotocol Label Switching (MPLS) point-to-multipoint (p2mp) Label 80 Switched Paths (LSPs). The document also describes the applicability 81 of out-band solutions to bootstrap a BFD session in this environment. 83 2. Conventions used in this document 85 2.1. Terminology 87 MPLS: Multiprotocol Label Switching 89 LSP: Label Switched Path 91 BFD: Bidirectional Forwarding Detection 93 p2mp: Point-to-Multipoint 95 FEC: Forwarding Equivalence Class 96 G-ACh: Generic Associated Channel 98 ACH: Associated Channel Header 100 GAL: G-ACh Label 102 2.2. Requirements Language 104 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 105 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 106 "OPTIONAL" in this document are to be interpreted as described in BCP 107 14 [RFC2119] [RFC8174] when, and only when, they appear in all 108 capitals, as shown here. 110 3. Multipoint BFD Encapsulation 112 [I-D.ietf-bfd-multipoint] defines how the tail of multipoint BFD 113 session demultiplexes received BFD control packet when Your 114 Discriminator is not set, i.e., equals zero. Because 115 [I-D.ietf-bfd-multipoint] uses BFD in Demand mode from the very start 116 of the p2mp BFD session, the head of BFD multipoint session transmits 117 all BFD control packets with Your Discriminator set to zero. As a 118 result, a tail cannot demultiplex BFD sessions using Your 119 Discriminator, as defined in [RFC5880]. [I-D.ietf-bfd-multipoint] 120 requires that to demultiplex BFD sessions the tail uses the source IP 121 address, My Discriminator and the identity of the multipoint tree 122 from which the Multipoint BFD Control packet was received. The 123 identification of the multipoint tree MAY be provided by the p2mp 124 MPLS LSP label in case of inclusive p-tree or upstream assigned label 125 in case of aggregate p-tree. If the BFD control packet is 126 encapsulated in IP/UDP, then the source IP address MUST be used to 127 demultiplex the received BFD control packet as described in 128 Section 3.1. The non-IP encapsulation case is described in 129 Section 3.2. 131 3.1. IP Encapsulation of Multipoint BFD 133 [I-D.ietf-bfd-multipoint] defines IP/UDP encapsulation for multipoint 134 BFD over p2mp MPLS LSP: 136 UDP destination port MUST be set to 3784; 138 destination IP address MUST be from the 127/8 range for IPv4 and 139 from the 0:0:0:0:0:FFFF:7F00/104 range for IPv6; 141 This specification further clarifies that: 143 if multiple alternative paths for the given p2mp LSP Forwarding 144 Equivalence Class (FEC) exist, the MultipointHead SHOULD use 145 Entropy Label [RFC6790] used for LSP Ping [RFC8029] to exercise 146 that particular alternative path; 148 or the MultipointHead MAY use the IP address discovered by LSP 149 Ping traceroute [RFC8029] as the destination IP address to 150 possibly exercise that particular alternate path. 152 3.2. Non-IP Encapsulation of Multipoint BFD 154 In some environments, the overhead of extra IP/UDP encapsulations may 155 be considered as overburden and make using more compact G-ACh 156 encapsulation attractive. Non-IP encapsulation for multipoint BFD 157 over p2mp MPLS LSP MUST use Generic Associated Channel (G-ACh) Label 158 (GAL) [RFC5586] at the bottom of the label stack followed by 159 Associated Channel Header (ACH). Channel Type field in ACH MUST be 160 set to MPLS-TP CV value (0x0023) [RFC6428]. To provide the identity 161 of the MultipointHead for the particular multipoint BFD session this 162 document defines new Source MEP ID IP Address type (TBA1) in 163 Section 6.1. If the Length value is 4, then the Value field contains 164 an IPv4 address. If the Length value is 16, then the Value field 165 contains an IPv6 address. Any other value of the Length field MUST 166 be considered as an error, and the BFD control packet MUST be 167 discarded. 169 4. Bootstrapping Multipoint BFD 171 4.1. LSP Ping 173 LSP Ping is the part of on-demand OAM toolset to detect and localize 174 defects in the data plane, and verify the control plane against the 175 data plane by ensuring that the LSP is mapped to the same FEC, at the 176 egress, as the ingress. 178 LSP Ping, as defined in [RFC6425], MAY be used to bootstrap 179 MultipointTail. If the LSP Ping used, it MUST include the Target FEC 180 TLV and the BFD Discriminator TLV defined in [RFC5884]. The Target 181 FEC TLV MUST use sub-TLVs defined in Section 3.1 [RFC6425]. It is 182 RECOMMENDED setting the value of Reply Mode field to "Do not reply" 183 [RFC8029] for the LSP Ping to bootstrap MultipointTail of the p2mp 184 BFD session. A MaultipointTail that receives the LSP Ping that 185 includes the BFD Discriminator TLV: 187 o MUST validate the LSP Ping; 189 o MUST associate the received BFD Discriminator value with the p2mp 190 LSP; 192 o MUST create p2mp BFD session and set bfd.SessionType = 193 MultipointTail as described in [I-D.ietf-bfd-multipoint]; 195 o MUST use the source IP address of LSP Ping, the value of BFD 196 Discriminator from the BFD Discriminator TLV, and the identity of 197 the p2mp LSP to properly demultiplex BFD sessions. 199 Besides bootstrapping a BFD session over a p2mp LSP, LSP Ping SHOULD 200 be used to verify the control plane against the data plane 201 periodically by checking that the p2mp LSP is mapped to the same FEC 202 at the MultipointHead and all active MultipointTails. The rate of 203 generation of these LSP Ping Echo request messages SHOULD be 204 significantly less than the rate of generation of the BFD Control 205 packets because LSP Ping requires more processing to validate the 206 consistency between the data plane and the control plane. An 207 implementation MAY provide configuration options to control the rate 208 of generation of the periodic LSP Ping Echo request messages. 210 4.2. Control Plane 212 BGP-BFD Attribute [I-D.ietf-bess-mvpn-fast-failover] MAY be used to 213 bootstrap multipoint BFD session on a tail. 215 5. Security Considerations 217 This document does not introduce new security aspects but inherits 218 all security considerations from [RFC5880], [RFC5884], [RFC7726], 219 [I-D.ietf-bfd-multipoint], [RFC8029], and [RFC6425]. 221 Also, BFD for p2mp MPLS LSP MUST follow the requirements listed in 222 section 4.1 [RFC4687] to avoid congestion in the control plane or the 223 data plane caused by the rate of generating BFD control packets. An 224 operator SHOULD consider the amount of extra traffic generated by 225 p2mp BFD when selecting the interval at which the MultipointHead will 226 transmit BFD control packets. Also, the operator MAY consider the 227 size of the packet the MultipointHead transmits periodically as using 228 IP/UDP encapsulation adds up to 28 octets, which is more than 50% of 229 BFD control packet length, comparing to G-ACh encapsulation. 231 6. IANA Considerations 233 6.1. Source MEP ID IP Address Type 235 IANA is required to allocate value (TBD) for the Source MEP ID IP 236 Address type from the "CC/CV MEP-ID TLV" registry which is under the 237 "Pseudowire Associated Channel Types" registry. 239 +-------+-------------+---------------+ 240 | Value | Description | Reference | 241 +-------+-------------+---------------+ 242 | TBA1 | IP Address | This document | 243 +-------+-------------+---------------+ 245 Table 1: Source MEP ID IP Address TLV Type 247 7. Acknowledgements 249 The author sincerely appreciates the comments received from Andrew 250 Malis. 252 8. References 254 8.1. Normative References 256 [I-D.ietf-bess-mvpn-fast-failover] 257 Morin, T., Kebler, R., and G. Mirsky, "Multicast VPN fast 258 upstream failover", draft-ietf-bess-mvpn-fast-failover-04 259 (work in progress), November 2018. 261 [I-D.ietf-bfd-multipoint] 262 Katz, D., Ward, D., Networks, J., and G. Mirsky, "BFD for 263 Multipoint Networks", draft-ietf-bfd-multipoint-19 (work 264 in progress), December 2018. 266 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 267 Requirement Levels", BCP 14, RFC 2119, 268 DOI 10.17487/RFC2119, March 1997, 269 . 271 [RFC5586] Bocci, M., Ed., Vigoureux, M., Ed., and S. Bryant, Ed., 272 "MPLS Generic Associated Channel", RFC 5586, 273 DOI 10.17487/RFC5586, June 2009, 274 . 276 [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection 277 (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010, 278 . 280 [RFC5884] Aggarwal, R., Kompella, K., Nadeau, T., and G. Swallow, 281 "Bidirectional Forwarding Detection (BFD) for MPLS Label 282 Switched Paths (LSPs)", RFC 5884, DOI 10.17487/RFC5884, 283 June 2010, . 285 [RFC6425] Saxena, S., Ed., Swallow, G., Ali, Z., Farrel, A., 286 Yasukawa, S., and T. Nadeau, "Detecting Data-Plane 287 Failures in Point-to-Multipoint MPLS - Extensions to LSP 288 Ping", RFC 6425, DOI 10.17487/RFC6425, November 2011, 289 . 291 [RFC6428] Allan, D., Ed., Swallow, G., Ed., and J. Drake, Ed., 292 "Proactive Connectivity Verification, Continuity Check, 293 and Remote Defect Indication for the MPLS Transport 294 Profile", RFC 6428, DOI 10.17487/RFC6428, November 2011, 295 . 297 [RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and 298 L. Yong, "The Use of Entropy Labels in MPLS Forwarding", 299 RFC 6790, DOI 10.17487/RFC6790, November 2012, 300 . 302 [RFC7726] Govindan, V., Rajaraman, K., Mirsky, G., Akiya, N., and S. 303 Aldrin, "Clarifying Procedures for Establishing BFD 304 Sessions for MPLS Label Switched Paths (LSPs)", RFC 7726, 305 DOI 10.17487/RFC7726, January 2016, 306 . 308 [RFC8029] Kompella, K., Swallow, G., Pignataro, C., Ed., Kumar, N., 309 Aldrin, S., and M. Chen, "Detecting Multiprotocol Label 310 Switched (MPLS) Data-Plane Failures", RFC 8029, 311 DOI 10.17487/RFC8029, March 2017, 312 . 314 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 315 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 316 May 2017, . 318 8.2. Informative References 320 [RFC4687] Yasukawa, S., Farrel, A., King, D., and T. Nadeau, 321 "Operations and Management (OAM) Requirements for Point- 322 to-Multipoint MPLS Networks", RFC 4687, 323 DOI 10.17487/RFC4687, September 2006, 324 . 326 Author's Address 328 Greg Mirsky 329 ZTE Corp. 331 Email: gregimirsky@gmail.com