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Chen 5 Expires: 23 March 2022 Huawei 6 19 September 2021 8 Operations, Administration and Maintenance (OAM) for Deterministic 9 Networks (DetNet) with MPLS Data Plane 10 draft-ietf-detnet-mpls-oam-04 12 Abstract 14 This document defines format and use principals of the Deterministic 15 Network (DetNet) service Associated Channel (ACH) over a DetNet 16 network with the MPLS data plane. The DetNet service ACH can be used 17 to carry test packets of active Operations, Administration, and 18 Maintenance protocols that are used to detect DetNet failures and 19 measure performance metrics. 21 Status of This Memo 23 This Internet-Draft is submitted in full conformance with the 24 provisions of BCP 78 and BCP 79. 26 Internet-Drafts are working documents of the Internet Engineering 27 Task Force (IETF). Note that other groups may also distribute 28 working documents as Internet-Drafts. The list of current Internet- 29 Drafts is at https://datatracker.ietf.org/drafts/current/. 31 Internet-Drafts are draft documents valid for a maximum of six months 32 and may be updated, replaced, or obsoleted by other documents at any 33 time. It is inappropriate to use Internet-Drafts as reference 34 material or to cite them other than as "work in progress." 36 This Internet-Draft will expire on 23 March 2022. 38 Copyright Notice 40 Copyright (c) 2021 IETF Trust and the persons identified as the 41 document authors. All rights reserved. 43 This document is subject to BCP 78 and the IETF Trust's Legal 44 Provisions Relating to IETF Documents (https://trustee.ietf.org/ 45 license-info) in effect on the date of publication of this document. 46 Please review these documents carefully, as they describe your rights 47 and restrictions with respect to this document. Code Components 48 extracted from this document must include Simplified BSD License text 49 as described in Section 4.e of the Trust Legal Provisions and are 50 provided without warranty as described in the Simplified BSD License. 52 Table of Contents 54 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 55 2. Conventions used in this document . . . . . . . . . . . . . . 3 56 2.1. Terminology and Acronyms . . . . . . . . . . . . . . . . 3 57 2.2. Keywords . . . . . . . . . . . . . . . . . . . . . . . . 4 58 3. Active OAM for DetNet Networks with MPLS Data Plane . . . . . 4 59 3.1. DetNet Active OAM Encapsulation . . . . . . . . . . . . . 5 60 3.2. DetNet Replication, Elimination, and Ordering Sub-functions 61 Interaction with Active OAM . . . . . . . . . . . . . . . 7 62 4. Use of Hybrid OAM in DetNet . . . . . . . . . . . . . . . . . 7 63 5. OAM Interworking Models . . . . . . . . . . . . . . . . . . . 8 64 5.1. OAM of DetNet MPLS Interworking with OAM of TSN . . . . . 8 65 5.2. OAM of DetNet MPLS Interworking with OAM of DetNet IP . . 9 66 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 67 7. Security Considerations . . . . . . . . . . . . . . . . . . . 9 68 8. Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . 9 69 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 70 9.1. Normative References . . . . . . . . . . . . . . . . . . 9 71 9.2. Informational References . . . . . . . . . . . . . . . . 10 72 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12 74 1. Introduction 76 [RFC8655] introduces and explains Deterministic Networks (DetNet) 77 architecture and how the Packet Replication and Elimination function 78 (PREF) can be used to ensure low packet drop ratio in DetNet domain. 80 Operations, Administration and Maintenance (OAM) protocols are used 81 to detect, localize defects in the network, and monitor network 82 performance. Some OAM functions, e.g., failure detection, work in 83 the network proactively, while others, e.g., defect localization, 84 usually performed on-demand. These tasks achieved by a combination 85 of active and hybrid, as defined in [RFC7799], OAM methods. 87 Also, this document defines format and use principals of the DetNet 88 service Associated Channel over a DetNet network with the MPLS data 89 plane [RFC8964]. 91 2. Conventions used in this document 93 2.1. Terminology and Acronyms 95 The term "DetNet OAM" used in this document interchangeably with 96 longer version "set of OAM protocols, methods and tools for 97 Deterministic Networks". 99 CW Control Word 101 DetNet Deterministic Networks 103 d-ACH DetNet Associated Channel Header 105 d-CW DetNet Control Word 107 DNH DetNet Header 109 GAL Generic Associated Channel Label 111 G-ACh Generic Associated Channel 113 OAM: Operations, Administration and Maintenance 115 PREF Packet Replication and Elimination Function 117 POF Packet Ordering Function 119 PW Pseudowire 121 RDI Remote Defect Indication 123 E2E End-to-end 125 CFM Connectivity Fault Management 127 BFD Bidirectional Forwarding Detection 129 TSN Time-Sensitive Network 131 F-Label A Detnet "forwarding" label that identifies the LSP used to 132 forward a DetNet flow across an MPLS PSN, e.g., a hop-by-hop label 133 used between label switching routers (LSR). 135 S-Label A DetNet "service" label that is used between DetNet nodes 136 that implement also the DetNet service sub-layer functions. An 137 S-Label is also used to identify a DetNet flow at DetNet service sub- 138 layer. 140 Underlay Network or Underlay Layer: The network that provides 141 connectivity between the DetNet nodes. MPLS network providing LSP 142 connectivity between DetNet nodes is an example of the underlay 143 layer. 145 DetNet Node - a node that is an actor in the DetNet domain. DetNet 146 domain edge node and node that performs PREF within the domain are 147 examples of DetNet node. 149 2.2. Keywords 151 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 152 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 153 "OPTIONAL" in this document are to be interpreted as described in BCP 154 14 [RFC2119] [RFC8174] when, and only when, they appear in all 155 capitals, as shown here. 157 3. Active OAM for DetNet Networks with MPLS Data Plane 159 OAM protocols and mechanisms act within the data plane of the 160 particular networking layer. And thus it is critical that the data 161 plane encapsulation supports OAM mechanisms in such a way to comply 162 with the OAM requirements listed in [I-D.tpmb-detnet-oam-framework]. 163 One of such examples that require special consideration is 164 requirement #5: 166 DetNet OAM packets MUST be in-band, i.e., follow precisely the 167 same path as DetNet data plane traffic both for unidirectional and 168 bi-directional DetNet paths. 170 The Det Net data plane encapsulation in transport network with MPLS 171 encapsulation specified in [RFC8964]. For the MPLS underlay network, 172 DetNet flows to be encapsulated analogous to pseudowires (PW) over 173 MPLS packet switched network, as described in [RFC3985], [RFC4385]. 174 Generic PW MPLS Control Word (CW), defined in [RFC4385], for DetNet 175 displayed in Figure 1. 177 0 1 2 3 178 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 179 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 180 |0 0 0 0| Sequence Number | 181 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 183 Figure 1: DetNet Control Word Format 185 PREF in the DetNet domain composed by a combination of nodes that 186 perform replication and elimination sub-functions. The elimination 187 sub-function always uses the S-Label and packet sequencing 188 information, e.g., the value in the Sequence Number field of DetNet 189 CW (d-CW). The replication sub-function uses the S-Label information 190 only. For data packets Figure 2 presents an example of PREF in 191 DetNet domain. 193 1111 11111111 111111 112212 112212 132213 194 CE1----EN1--------R1-------R2-------R3--------EN2----CE2 195 \2 22222/ 3 / 196 \2222222 /----+ 3 / 197 +------R4------------------------+ 198 333333333333333333333333 200 Figure 2: DetNet Data Plane Based on PW 202 3.1. DetNet Active OAM Encapsulation 204 DetNet OAM, like PW OAM, uses PW Associated Channel Header defined in 205 [RFC4385]. Figure 3 displays the encapsulation of a DetNet MPLS 206 [RFC8964] active OAM packet. 208 +---------------------------------+ 209 | | 210 | DetNet App-Flow | 211 | Payload Packet | 212 | | 213 +---------------------------------+ <--\ 214 | DetNet Associated Channel Header| | 215 +---------------------------------+ +--> DetNet active OAM 216 | S-Label | | MPLS encapsulation 217 +---------------------------------+ | 218 | [ F-Label(s) ] | | 219 +---------------------------------+ <--/ 220 | Data-Link | 221 +---------------------------------+ 222 | Physical | 223 +---------------------------------+ 225 Figure 3: DetNet Active OAM Packet Encapsulation in MPLS Data Plane 227 Figure 4 displays encapsulation of a test packet of an active DetNet 228 OAM protocol in case of MPLS-over-UDP/IP [RFC9025]. 230 +---------------------------------+ 231 | | 232 | DetNet App-Flow | 233 | Payload Packet | 234 | | 235 +---------------------------------+ <--\ 236 | DetNet Associated Channel Header| | 237 +---------------------------------+ +--> DetNet active OAM 238 | S-Label | | MPLS encapsulation 239 +---------------------------------+ | 240 | [ F-label(s) ] | | 241 +---------------------------------+ <--+ 242 | UDP Header | | 243 +---------------------------------+ +--> DetNet data plane 244 | IP Header | | IP encapsulation 245 +---------------------------------+ <--/ 246 | Data-Link | 247 +---------------------------------+ 248 | Physical | 249 +---------------------------------+ 251 Figure 4: DetNet Active OAM Packet Encapsulation in MPLS-over-UDP/IP 253 Figure 5 displays the format of the DetNet Associated Channel Header 254 (d-ACH). 256 0 1 2 3 257 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 258 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 259 |0 0 0 1|Version|Sequence Number| Channel Type | 260 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 262 Figure 5: DetNet Associated Channel Header Format 264 The meanings of the fields in the d-ACH are: 266 Bits 0..3 MUST be 0b0001. This value of the first nibble allows 267 the packet to be distinguished from an IP packet [RFC4928] and a 268 DetNet data packet [RFC8964]. 270 Version: this is the version number of the d-ACH. This 271 specification defines version 0. 273 Sequence Number: this is unsigned eight bits-long field. The 274 originating DetNet node MUST set the value of the Sequence Number 275 field to a non-zero before packet being transmitted. The 276 originating node MUST monotonically increase the value of the 277 Sequence Number field for the every next active OAM packet. 279 Channel Type: the value of DetNet Associated Channel Type is one 280 of values defined in the IANA PW Associated Channel Type registry. 282 The DetNet flow, according to [RFC8964], is identified by the S-label 283 that MUST be at the bottom of the stack. Active OAM packet MUST have 284 d-ACH immediately following the S-label. 286 3.2. DetNet Replication, Elimination, and Ordering Sub-functions 287 Interaction with Active OAM 289 At the DetNet service layer, special functions MAY be applied to the 290 particular DetNet flow - PREF to potentially lower packet loss, 291 improve the probability of on-time packet delivery and Packet 292 Ordering Function (POF) to ensure in-order packet delivery. As data 293 and the active OAM packets have the same Flow ID, S-label, sub- 294 functions that rely on sequencing information in the DetNet service 295 layer MUST process 28 MSBs of the d-ACH as the source of the 296 sequencing information for the OAM packet. 298 4. Use of Hybrid OAM in DetNet 300 Hybrid OAM methods are used in performance monitoring and defined in 301 [RFC7799] as: 303 Hybrid Methods are Methods of Measurement that use a combination 304 of Active Methods and Passive Methods. 306 A hybrid measurement method may produce metrics as close to passive, 307 but it still alters something in a data packet even if that is the 308 value of a designated field in the packet encapsulation. One example 309 of such a hybrid measurement method is the Alternate Marking method 310 described in [RFC8321]. Reserving the field for the Alternate 311 Marking method in the DetNet Header will enhance available to an 312 operator set of DetNet OAM tools. 314 5. OAM Interworking Models 316 Interworking of two OAM domains that utilize different networking 317 technology can be realized either by a peering or a tunneling model. 318 In a peering model, OAM domains are within the corresponding network 319 domain. When using the peering model, state changes that are 320 detected by a Fault Management OAM protocol can be mapped from one 321 OAM domain into another or a notification, e.g., an alarm, can be 322 sent to a central controller. In the tunneling model of OAM 323 interworking, usually, only one active OAM protocol is used. Its 324 test packets are tunneled through another domain along with the data 325 flow, thus ensuring the fate sharing among test and data packets. 327 5.1. OAM of DetNet MPLS Interworking with OAM of TSN 329 Active DetNet OAM is required to provide the E2E fault management and 330 performance monitoring for a DetNet flow. Interworking of DetNet 331 active OAM with MPLS data plane with the IEEE 802.1 Time-Sensitive 332 Networking (TSN) domain based on [RFC9037]. 334 In the case of the peering model is used in the fault management OAM, 335 then the node that borders both TSN and DetNet MPLS domains MUST 336 support [RFC7023]. [RFC7023] specified the mapping of defect states 337 between Ethernet Attachment Circuits (ACs) and associated Ethernet 338 PWs that are part of an end-to-end (E2E) emulated Ethernet service. 339 Requirements and mechanisms described in [RFC7023] are equally 340 applicable to using the peering model to achieve E2E FM OAM over 341 DetNet MPLS and TSN domains. The Connectivity Fault Management (CFM) 342 protocol [IEEE.CFM] or in [ITU.Y1731] can provide fast detection of a 343 failure in the TSN segment of the DetNet service. In the DetNet MPLS 344 domain BFD (Bidirectional Forwarding Detection), specified in 345 [RFC5880] and [RFC5885], can be used. To provide E2E failure 346 detection, the TSN segment might be presented as a concatenated with 347 the DetNet MPLS and the Section 6.8.17 [RFC5880] MAY be used to 348 inform the upstream DetNet MPLS node of a failure of the TSN segment. 349 Performance monitoring can be supported by [RFC6374] in the DetNet 350 MPLS and [ITU.Y1731] in the TSN domains, respectively. Performance 351 objectives for each domain should refer to metrics that additive or 352 be defined for each domain separately. 354 The following considerations are to be realized when using the 355 tunneling model of OAM interworking between DetNet MPLS and TSN 356 domains: 358 * Active OAM test packet MUST be mapped to the same TSN Stream ID as 359 the monitored DetNet flow. 361 * Active OAM test packets MUST be treated in the TSN domain based on 362 its S-label and CoS marking (TC field value). 364 Note that the tunneling model of the OAM interworking requires that 365 the remote peer of the E2E OAM domain supports the active OAM 366 protocol selected on the ingress endpoint. For example, if BFD is 367 used for proactive path continuity monitoring in the DetNet MPLS 368 domain, a TSN endpoint of the DetNet service has also support BFD as 369 defined in [RFC5885]. 371 5.2. OAM of DetNet MPLS Interworking with OAM of DetNet IP 373 Interworking between active OAM segments in DetNet MPLS and DetNet IP 374 domains can also be realized using either the peering or the 375 tunneling model, as discussed in Section 5.1. Using the same 376 protocol, e.g., BFD, over both segments, simplifies the mapping of 377 errors in the peering model. To provide the performance monitoring 378 over a DetNet IP domain STAMP [RFC8762] and its extensions [RFC8972] 379 can be used. 381 6. IANA Considerations 383 This document does not have any requests for IANA allocation. This 384 section can be deleted before the publication of the draft. 386 7. Security Considerations 388 Additionally, security considerations discussed in DetNet 389 specifications: [RFC8655], [RFC9055], [RFC8964] are applicable to 390 this document. Security concerns and issues related to MPLS OAM 391 tools like LSP Ping [RFC8029], BFD over PW [RFC5885] also apply to 392 this specification. 394 8. Acknowledgment 396 Authors extend their appreciation to Pascal Thubert for his 397 insightful comments and productive discussion that helped to improve 398 the document. 400 9. References 402 9.1. Normative References 404 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 405 Requirement Levels", BCP 14, RFC 2119, 406 DOI 10.17487/RFC2119, March 1997, 407 . 409 [RFC7023] Mohan, D., Ed., Bitar, N., Ed., Sajassi, A., Ed., DeLord, 410 S., Niger, P., and R. Qiu, "MPLS and Ethernet Operations, 411 Administration, and Maintenance (OAM) Interworking", 412 RFC 7023, DOI 10.17487/RFC7023, October 2013, 413 . 415 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 416 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 417 May 2017, . 419 [RFC8655] Finn, N., Thubert, P., Varga, B., and J. Farkas, 420 "Deterministic Networking Architecture", RFC 8655, 421 DOI 10.17487/RFC8655, October 2019, 422 . 424 [RFC8964] Varga, B., Ed., Farkas, J., Berger, L., Malis, A., Bryant, 425 S., and J. Korhonen, "Deterministic Networking (DetNet) 426 Data Plane: MPLS", RFC 8964, DOI 10.17487/RFC8964, January 427 2021, . 429 [RFC9025] Varga, B., Ed., Farkas, J., Berger, L., Malis, A., and S. 430 Bryant, "Deterministic Networking (DetNet) Data Plane: 431 MPLS over UDP/IP", RFC 9025, DOI 10.17487/RFC9025, April 432 2021, . 434 9.2. Informational References 436 [I-D.tpmb-detnet-oam-framework] 437 Mirsky, G., Theoleyre, F., Papadopoulos, G. Z., and C. J. 438 Bernardos, "Framework of Operations, Administration and 439 Maintenance (OAM) for Deterministic Networking (DetNet)", 440 Work in Progress, Internet-Draft, draft-tpmb-detnet-oam- 441 framework-01, 30 March 2021, 442 . 445 [IEEE.CFM] IEEE, "Connectivity Fault Management clause of IEEE 446 802.1Q", IEEE 802.1Q, 2013. 448 [ITU.Y1731] 449 ITU-T, "OAM functions and mechanisms for Ethernet based 450 Networks", ITU-T Recommendation G.8013/Y.1731, November 451 2013. 453 [RFC3985] Bryant, S., Ed. and P. Pate, Ed., "Pseudo Wire Emulation 454 Edge-to-Edge (PWE3) Architecture", RFC 3985, 455 DOI 10.17487/RFC3985, March 2005, 456 . 458 [RFC4385] Bryant, S., Swallow, G., Martini, L., and D. McPherson, 459 "Pseudowire Emulation Edge-to-Edge (PWE3) Control Word for 460 Use over an MPLS PSN", RFC 4385, DOI 10.17487/RFC4385, 461 February 2006, . 463 [RFC4928] Swallow, G., Bryant, S., and L. Andersson, "Avoiding Equal 464 Cost Multipath Treatment in MPLS Networks", BCP 128, 465 RFC 4928, DOI 10.17487/RFC4928, June 2007, 466 . 468 [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection 469 (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010, 470 . 472 [RFC5885] Nadeau, T., Ed. and C. Pignataro, Ed., "Bidirectional 473 Forwarding Detection (BFD) for the Pseudowire Virtual 474 Circuit Connectivity Verification (VCCV)", RFC 5885, 475 DOI 10.17487/RFC5885, June 2010, 476 . 478 [RFC6374] Frost, D. and S. Bryant, "Packet Loss and Delay 479 Measurement for MPLS Networks", RFC 6374, 480 DOI 10.17487/RFC6374, September 2011, 481 . 483 [RFC7799] Morton, A., "Active and Passive Metrics and Methods (with 484 Hybrid Types In-Between)", RFC 7799, DOI 10.17487/RFC7799, 485 May 2016, . 487 [RFC8029] Kompella, K., Swallow, G., Pignataro, C., Ed., Kumar, N., 488 Aldrin, S., and M. Chen, "Detecting Multiprotocol Label 489 Switched (MPLS) Data-Plane Failures", RFC 8029, 490 DOI 10.17487/RFC8029, March 2017, 491 . 493 [RFC8321] Fioccola, G., Ed., Capello, A., Cociglio, M., Castaldelli, 494 L., Chen, M., Zheng, L., Mirsky, G., and T. Mizrahi, 495 "Alternate-Marking Method for Passive and Hybrid 496 Performance Monitoring", RFC 8321, DOI 10.17487/RFC8321, 497 January 2018, . 499 [RFC8762] Mirsky, G., Jun, G., Nydell, H., and R. Foote, "Simple 500 Two-Way Active Measurement Protocol", RFC 8762, 501 DOI 10.17487/RFC8762, March 2020, 502 . 504 [RFC8972] Mirsky, G., Min, X., Nydell, H., Foote, R., Masputra, A., 505 and E. Ruffini, "Simple Two-Way Active Measurement 506 Protocol Optional Extensions", RFC 8972, 507 DOI 10.17487/RFC8972, January 2021, 508 . 510 [RFC9037] Varga, B., Ed., Farkas, J., Malis, A., and S. Bryant, 511 "Deterministic Networking (DetNet) Data Plane: MPLS over 512 IEEE 802.1 Time-Sensitive Networking (TSN)", RFC 9037, 513 DOI 10.17487/RFC9037, June 2021, 514 . 516 [RFC9055] Grossman, E., Ed., Mizrahi, T., and A. Hacker, 517 "Deterministic Networking (DetNet) Security 518 Considerations", RFC 9055, DOI 10.17487/RFC9055, June 519 2021, . 521 Authors' Addresses 523 Greg Mirsky 524 Ericsson 526 Email: gregimirsky@gmail.com 528 Mach(Guoyi) Chen 529 Huawei 531 Email: mach.chen@huawei.com