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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 DetNet Working Group G. Mirsky 3 Internet-Draft ZTE Corp. 4 Intended status: Standards Track M. Chen 5 Expires: September 28, 2020 Huawei 6 March 27, 2020 8 Operations, Administration and Maintenance (OAM) for Deterministic 9 Networks (DetNet) with MPLS Data Plane 10 draft-ietf-detnet-mpls-oam-00 12 Abstract 14 This document lists functional requirements for Operations, 15 Administration, and Maintenance (OAM) toolset in Deterministic 16 Networks (DetNet) and, using these requirements; defines format and 17 use principals of the DetNet service Associated Channel over a DetNet 18 network with the MPLS data plane.. 20 Status of This Memo 22 This Internet-Draft is submitted in full conformance with the 23 provisions of BCP 78 and BCP 79. 25 Internet-Drafts are working documents of the Internet Engineering 26 Task Force (IETF). Note that other groups may also distribute 27 working documents as Internet-Drafts. The list of current Internet- 28 Drafts is at https://datatracker.ietf.org/drafts/current/. 30 Internet-Drafts are draft documents valid for a maximum of six months 31 and may be updated, replaced, or obsoleted by other documents at any 32 time. It is inappropriate to use Internet-Drafts as reference 33 material or to cite them other than as "work in progress." 35 This Internet-Draft will expire on September 28, 2020. 37 Copyright Notice 39 Copyright (c) 2020 IETF Trust and the persons identified as the 40 document authors. All rights reserved. 42 This document is subject to BCP 78 and the IETF Trust's Legal 43 Provisions Relating to IETF Documents 44 (https://trustee.ietf.org/license-info) in effect on the date of 45 publication of this document. Please review these documents 46 carefully, as they describe your rights and restrictions with respect 47 to this document. Code Components extracted from this document must 48 include Simplified BSD License text as described in Section 4.e of 49 the Trust Legal Provisions and are provided without warranty as 50 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 . . . . . . . . . . . . . . . . . . . . . . . 3 57 2.2. Keywords . . . . . . . . . . . . . . . . . . . . . . . . 4 58 3. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 4 59 4. Active OAM for DetNet Networks with MPLS Data Plane . . . . . 5 60 4.1. DetNet Active OAM Encapsulation . . . . . . . . . . . . . 6 61 4.2. DetNet Replication, Elimination, and Ordering Sub- 62 functions Interaction with Active OAM . . . . . . . . . . 9 63 5. Use of Hybrid OAM in DetNet . . . . . . . . . . . . . . . . . 9 64 6. OAM of DetNet MPLS Interworking with OAM of DetNet IP . . . . 9 65 7. OAM of DetNet MPLS Interworking with OAM of TSN . . . . . . . 9 66 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 67 9. Security Considerations . . . . . . . . . . . . . . . . . . . 9 68 10. Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . 10 69 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 70 11.1. Normative References . . . . . . . . . . . . . . . . . . 10 71 11.2. Informational References . . . . . . . . . . . . . . . . 10 72 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 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 This document lists the functional requirements toward OAM for DetNet 88 domain. The list can further be used for gap analysis of available 89 OAM tools to identify possible enhancements of existing or whether 90 new OAM tools are required to support proactive and on-demand path 91 monitoring and service validation. Also, this document defines 92 format and use principals of the DetNet service Associated Channel 93 over a DetNet network with the MPLS data plane 94 [I-D.ietf-detnet-mpls]. 96 2. Conventions used in this document 98 2.1. Terminology 100 The term "DetNet OAM" used in this document interchangeably with 101 longer version "set of OAM protocols, methods and tools for 102 Deterministic Networks". 104 CW Control Word 106 DetNet Deterministic Networks 108 d-ACH DetNet Associated Channel Header 110 d-CW DetNet Control Word 112 DNH DetNet Header 114 GAL Generic Associated Channel Label 116 G-ACh Generic Associated Channel 118 OAM: Operations, Administration and Maintenance 120 PREF Packet Replication and Elimination Function 122 POF Packet Ordering Function 124 PW Pseudowire 126 RDI Remote Defect Indication 128 TSN Time-Sensitive Network 130 F-Label A Detnet "forwarding" label that identifies the LSP used to 131 forward a DetNet flow across an MPLS PSN, e.g., a hop-by-hop label 132 used between label switching routers (LSR). 134 S-Label A DetNet "service" label that is used between DetNet nodes 135 that implement also the DetNet service sub-layer functions. An 136 S-Label is also used to identify a DetNet flow at DetNet service sub- 137 layer. 139 Underlay Network or Underlay Layer: The network that provides 140 connectivity between the DetNet nodes. MPLS network providing LSP 141 connectivity between DetNet nodes is an example of the underlay 142 layer. 144 DetNet Node - a node that is an actor in the DetNet domain. DetNet 145 domain edge node and node that performs PREF within the domain are 146 examples of DetNet node. 148 2.2. Keywords 150 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 151 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 152 "OPTIONAL" in this document are to be interpreted as described in BCP 153 14 [RFC2119] [RFC8174] when, and only when, they appear in all 154 capitals, as shown here. 156 3. Requirements 158 This section lists requirements for OAM in DetNet domain with MPLS 159 data plane: 161 1. It MUST be possible to initiate DetNet OAM session from any 162 DetNet node towards another DetNet node(s) within given domain. 164 2. It SHOULD be possible to initialize DetNet OAM session from a 165 centralized controller. 167 3. DetNet OAM MUST support proactive and on-demand OAM monitoring 168 and measurement methods. 170 4. DetNet OAM packets MUST be in-band, i.e., follow precisely the 171 same path as DetNet data plane traffic. 173 5. DetNet OAM MUST support unidirectional OAM methods, continuity 174 check, connectivity verification, and performance measurement. 176 6. DetNet OAM MUST support bi-directional OAM methods. Such OAM 177 methods MAY combine in-band monitoring or measurement in the 178 forward direction and out-of-bound notification in the reverse 179 direction, i.e., from egress to ingress end point of the OAM 180 test session. 182 7. DetNet OAM MUST support proactive monitoring of a DetNet node 183 availability in the given DetNet domain. 185 8. DetNet OAM MUST support Path Maximum Transmission Unit 186 discovery. 188 9. DetNet OAM MUST support Remote Defect Indication (RDI) 189 notification to the DetNet node performing continuity checking. 191 10. DetNet OAM MUST support performance measurement methods. 193 11. DetNet OAM MAY support hybrid performance measurement methods. 195 12. DetNet OAM MUST support unidirectional performance measurement 196 methods. Calculated performance metrics MUST include but are 197 not limited to throughput, packet loss, delay and delay 198 variation metrics. [RFC6374] provides excellent details on 199 performance measurement and performance metrics. 201 13. DetNet OAM MUST support defect notification mechanism, like 202 Alarm Indication Signal. Any DetNet node in the given DetNet 203 domain MAY originate a defect notification addressed to any 204 subset of nodes within the domain. 206 14. DetNet OAM MUST support methods to enable survivability of the 207 DetNet domain. These recovery methods MAY use protection 208 switching and restoration. 210 15. DetNet OAM MUST support the discovery of Packet Replication, 211 Elimination, and Order preservation sub-functions locations in 212 the domain. 214 16. DetNet OAM MUST support testing of Packet Replication, 215 Elimination, and Order preservation sub-functions in the domain. 217 17. DetNet OAM MUST support monitoring any sub-set of paths 218 traversed through the DetNet domain by the DetNet flow. 220 4. Active OAM for DetNet Networks with MPLS Data Plane 222 OAM protocols and mechanisms act within the data plane of the 223 particular networking layer. And thus it is critical that the data 224 plane encapsulation supports OAM mechanisms in such a way to comply 225 with the above-listed requirements. One of such examples that 226 require special consideration is requirement #5: 228 DetNet OAM packets MUST be in-band, i.e., follow precisely the 229 same path as DetNet data plane traffic both for unidirectional and 230 bi-directional DetNet paths. 232 The Det Net data plane encapsulation in transport network with MPLS 233 encapsulation specified in [I-D.ietf-detnet-mpls]. For the MPLS 234 underlay network, DetNet flows to be encapsulated analogous to 235 pseudowires (PW) over MPLS packet switched network, as described in 236 [RFC3985], [RFC4385]. Generic PW MPLS Control Word (CW), defined in 237 [RFC4385], for DetNet displayed in Figure 1. 239 0 1 2 3 240 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 1 241 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 242 |0 0 0 0| Sequence Number | 243 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 245 Figure 1: DetNet Control Word Format 247 PREF in the DetNet domain composed by a combination of nodes that 248 perform replication and elimination sub-functions. The elimination 249 sub-function always uses the S-Label and packet sequencing 250 information, e.g., the value in the Sequence Number field of DetNet 251 CW (d-CW). The replication sub-function uses the S-Label information 252 only. For data packets Figure 2 presents an example of PREF in 253 DetNet domain. 255 1111 11111111 111111 112212 112212 132213 256 CE1----EN1--------R1-------R2-------R3--------EN2----CE2 257 \2 22222/ 3 / 258 \2222222 /----+ 3 / 259 +------R4------------------------+ 260 333333333333333333333333 262 Figure 2: DetNet Data Plane Based on PW 264 4.1. DetNet Active OAM Encapsulation 266 DetNet OAM, like PW OAM, uses PW Associated Channel Header defined in 267 [RFC4385]. Figure 3 displays the encapsulation of a DetNet MPLS 268 [I-D.ietf-detnet-mpls] active OAM packet. 270 +---------------------------------+ 271 | | 272 | DetNet App-Flow | 273 | Payload Packet | 274 | | 275 +---------------------------------+ <--\ 276 | DetNet Associated Channel Header| | 277 +---------------------------------+ +--> DetNet active OAM 278 | S-Label | | MPLS encapsulation 279 +---------------------------------+ | 280 | [ F-Label(s) ] | | 281 +---------------------------------+ <--/ 282 | Data-Link | 283 +---------------------------------+ 284 | Physical | 285 +---------------------------------+ 287 Figure 3: DetNet Active OAM Packet Encapsulation in MPLS Data Plane 289 Figure 4 displays encapsulation of a test packet of an active DetNet 290 OAM protocol in case of MPLS-over-UDP/IP 291 [I-D.ietf-detnet-mpls-over-udp-ip]. 293 +---------------------------------+ 294 | | 295 | DetNet App-Flow | 296 | Payload Packet | 297 | | 298 +---------------------------------+ <--\ 299 | DetNet Associated Channel Header| | 300 +---------------------------------+ +--> DetNet active OAM 301 | S-Label | | MPLS encapsulation 302 +---------------------------------+ | 303 | [ F-label(s) ] | | 304 +---------------------------------+ <--+ 305 | UDP Header | | 306 +---------------------------------+ +--> DetNet data plane 307 | IP Header | | IP encapsulation 308 +---------------------------------+ <--/ 309 | Data-Link | 310 +---------------------------------+ 311 | Physical | 312 +---------------------------------+ 314 Figure 4: DetNet Active OAM Packet Encapsulation in MPLS-over-UDP/IP 315 Figure 5 displays the format of the DetNet Associated Channel Header 316 (d-ACH). 318 0 1 2 3 319 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 1 320 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 321 |0 0 0 1|Version|Sequence Number| Channel Type | 322 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 324 Figure 5: DetNet Associated Channel Header Format 326 The meanings of the fields in the d-ACH are: 328 Bits 0..3 MUST be 0b0001. This value of the first nibble allows 329 the packet to be distinguished from an IP packet [RFC4928] and a 330 DetNet data packet [I-D.ietf-detnet-mpls]. 332 Version: this is the version number of the d-ACH. This 333 specification defines version 0. 335 Sequence Number: this is unsigned eight bits-long field. The 336 originating DetNet node MUST set the value of the Sequence Number 337 field to a non-zero before packet being transmitted. The 338 originating node MUST monotonically increase the value of the 339 Sequence Number field for the every next active OAM packet. 341 Channel Type: the value of DetNet Associated Channel Type is one 342 of values defined in the IANA PW Associated Channel Type registry. 344 The DetNet flow, according to [I-D.ietf-detnet-mpls], is identified 345 by the S-label that MUST be at the bottom of the stack. Active OAM 346 packet MUST have d-ACH immediately following the S-label. 348 Special consideration for DetNet active OAM with MPLS data plane 349 interworking with OAM in IEEE 802.1 Time-Sensitive Networking (TSN) 350 domain based on [I-D.ietf-detnet-mpls-over-tsn]: 352 o Active OAM test packet MUST be mapped to the same TSN Stream ID as 353 the monitored DetNet flow . 355 o Active OAM test packets MUST be treated in the TSN domain based on 356 its S-label and CoS marking (TC field value). 358 4.2. DetNet Replication, Elimination, and Ordering Sub-functions 359 Interaction with Active OAM 361 At the DetNet service layer, special functions MAY be applied to the 362 particular DetNet flow - PREF to potentially lower packet loss, 363 improve the probability of on-time packet delivery and Packet 364 Ordering Function (POF) to ensure in-order packet delivery. As data 365 and the active OAM packets have the same Flow ID, S-label, sub- 366 functions that rely on sequencing information in the DetNet service 367 layer MUST process 28 MSBs of the d-ACH as the source of the 368 sequencing information for the OAM packet. 370 5. Use of Hybrid OAM in DetNet 372 Hybrid OAM methods are used in performance monitoring and defined in 373 [RFC7799] as: 375 Hybrid Methods are Methods of Measurement that use a combination 376 of Active Methods and Passive Methods. 378 A hybrid measurement method may produce metrics as close to passive, 379 but it still alters something in a data packet even if that is the 380 value of a designated field in the packet encapsulation. One example 381 of such a hybrid measurement method is the Alternate Marking method 382 described in [RFC8321]. Reserving the field for the Alternate 383 Marking method in the DetNet Header will enhance available to an 384 operator set of DetNet OAM tools. 386 6. OAM of DetNet MPLS Interworking with OAM of DetNet IP 388 TBA 390 7. OAM of DetNet MPLS Interworking with OAM of TSN 392 TBA 394 8. IANA Considerations 396 TBA 398 9. Security Considerations 400 This document lists the OAM requirements for a DetNet domain and does 401 not raise any security concerns or issues in addition to ones common 402 to networking. 404 10. Acknowledgment 406 Authors extend their appreciation to Pascal Thubert for his 407 insightful comments and productive discussion that helped to improve 408 the document. 410 11. References 412 11.1. Normative References 414 [I-D.ietf-detnet-mpls] 415 Varga, B., Farkas, J., Berger, L., Fedyk, D., Malis, A., 416 Bryant, S., and J. Korhonen, "DetNet Data Plane: MPLS", 417 draft-ietf-detnet-mpls-05 (work in progress), February 418 2020. 420 [I-D.ietf-detnet-mpls-over-tsn] 421 Varga, B., Farkas, J., Malis, A., and S. Bryant, "DetNet 422 Data Plane: MPLS over IEEE 802.1 Time Sensitive Networking 423 (TSN)", draft-ietf-detnet-mpls-over-tsn-02 (work in 424 progress), March 2020. 426 [I-D.ietf-detnet-mpls-over-udp-ip] 427 Varga, B., Farkas, J., Berger, L., Malis, A., and S. 428 Bryant, "DetNet Data Plane: MPLS over UDP/IP", draft-ietf- 429 detnet-mpls-over-udp-ip-05 (work in progress), February 430 2020. 432 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 433 Requirement Levels", BCP 14, RFC 2119, 434 DOI 10.17487/RFC2119, March 1997, 435 . 437 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 438 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 439 May 2017, . 441 [RFC8655] Finn, N., Thubert, P., Varga, B., and J. Farkas, 442 "Deterministic Networking Architecture", RFC 8655, 443 DOI 10.17487/RFC8655, October 2019, 444 . 446 11.2. Informational References 448 [RFC3985] Bryant, S., Ed. and P. Pate, Ed., "Pseudo Wire Emulation 449 Edge-to-Edge (PWE3) Architecture", RFC 3985, 450 DOI 10.17487/RFC3985, March 2005, 451 . 453 [RFC4385] Bryant, S., Swallow, G., Martini, L., and D. McPherson, 454 "Pseudowire Emulation Edge-to-Edge (PWE3) Control Word for 455 Use over an MPLS PSN", RFC 4385, DOI 10.17487/RFC4385, 456 February 2006, . 458 [RFC4928] Swallow, G., Bryant, S., and L. Andersson, "Avoiding Equal 459 Cost Multipath Treatment in MPLS Networks", BCP 128, 460 RFC 4928, DOI 10.17487/RFC4928, June 2007, 461 . 463 [RFC6374] Frost, D. and S. Bryant, "Packet Loss and Delay 464 Measurement for MPLS Networks", RFC 6374, 465 DOI 10.17487/RFC6374, September 2011, 466 . 468 [RFC7799] Morton, A., "Active and Passive Metrics and Methods (with 469 Hybrid Types In-Between)", RFC 7799, DOI 10.17487/RFC7799, 470 May 2016, . 472 [RFC8321] Fioccola, G., Ed., Capello, A., Cociglio, M., Castaldelli, 473 L., Chen, M., Zheng, L., Mirsky, G., and T. Mizrahi, 474 "Alternate-Marking Method for Passive and Hybrid 475 Performance Monitoring", RFC 8321, DOI 10.17487/RFC8321, 476 January 2018, . 478 Authors' Addresses 480 Greg Mirsky 481 ZTE Corp. 483 Email: gregimirsky@gmail.com 485 Mach(Guoyi) Chen 486 Huawei 488 Email: mach.chen@huawei.com