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Checking references for intended status: Informational ---------------------------------------------------------------------------- == Outdated reference: A later version (-16) exists of draft-ietf-detnet-security-13 Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 DetNet B. Varga, Ed. 3 Internet-Draft J. Farkas 4 Intended status: Informational Ericsson 5 Expires: August 16, 2021 A. Malis 6 Malis Consulting 7 S. Bryant 8 Futurewei Technologies 9 February 12, 2021 11 DetNet Data Plane: MPLS over IEEE 802.1 Time-Sensitive Networking (TSN) 12 draft-ietf-detnet-mpls-over-tsn-06 14 Abstract 16 This document specifies the Deterministic Networking MPLS data plane 17 when operating over an IEEE 802.1 Time-Sensitive Networking (TSN) 18 sub-network. This document does not define new procedures or 19 processes. Whenever this document makes requirements statements or 20 recommendations, these are taken from normative text in the 21 referenced RFCs. 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 August 16, 2021. 40 Copyright Notice 42 Copyright (c) 2021 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. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 59 2.1. Terms Used in This Document . . . . . . . . . . . . . . . 3 60 2.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 3 61 3. DetNet MPLS Data Plane Overview . . . . . . . . . . . . . . . 4 62 4. DetNet MPLS Operation Over IEEE 802.1 TSN Sub-Networks . . . 4 63 4.1. Functions for DetNet Flow to TSN Stream Mapping . . . . . 6 64 4.2. TSN requirements of MPLS DetNet nodes . . . . . . . . . . 6 65 4.3. Service protection within the TSN sub-network . . . . . . 8 66 4.4. Aggregation during DetNet flow to TSN Stream mapping . . 8 67 5. Management and Control Implications . . . . . . . . . . . . . 8 68 6. Security Considerations . . . . . . . . . . . . . . . . . . . 10 69 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 70 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11 71 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 11 72 9.1. Normative References . . . . . . . . . . . . . . . . . . 11 73 9.2. Informative References . . . . . . . . . . . . . . . . . 11 74 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12 76 1. Introduction 78 Deterministic Networking (DetNet) is a service that can be offered by 79 a network to DetNet flows. DetNet provides these flows with low 80 packet loss rates and assured maximum end-to-end delivery latency. 81 General background and concepts of DetNet can be found in [RFC8655]. 83 The DetNet Architecture decomposes the DetNet related data plane 84 functions into two sub-layers: a service sub-layer and a forwarding 85 sub-layer. The service sub-layer is used to provide DetNet service 86 protection and reordering. The forwarding sub-layer is used to 87 provide congestion protection (low loss, assured latency, and limited 88 reordering) leveraging MPLS Traffic Engineering mechanisms. 90 [RFC8964] specifies the DetNet data plane operation for MPLS-based 91 Packet Switched Network (PSN). MPLS encapsulated DetNet flows can be 92 carried over network technologies that can provide the DetNet 93 required level of service. This document focuses on the scenario 94 where MPLS (DetNet) nodes are interconnected by a IEEE 802.1 TSN sub- 95 network. There is close cooperation between the IETF DetNet WG and 96 the IEEE 802.1 TSN TG. 98 2. Terminology 100 2.1. Terms Used in This Document 102 This document uses the terminology established in the DetNet 103 architecture [RFC8655] and [RFC8964]. TSN specific terms are defined 104 in the TSN TG of IEEE 802.1 Working Group. The reader is assumed to 105 be familiar with these documents and their terminology. 107 2.2. Abbreviations 109 The following abbreviations are used in this document: 111 A-Label Aggregation label, a special case of an S-Label. 113 CW Control Word. 115 DetNet Deterministic Networking. 117 DF DetNet Flow. 119 F-Label Forwarding label that identifies the LSP used by a 120 DetNet flow. 122 FRER Frame Replication and Elimination for Redundancy (TSN 123 function). 125 L2 Layer 2. 127 L3 Layer 3. 129 LSR Label Switching Router. 131 MPLS Multiprotocol Label Switching. 133 PE Provider Edge. 135 PREOF Packet Replication, Elimination and Ordering Functions. 137 PSN Packet Switched Network. 139 PW PseudoWire. 141 S-PE Switching Provider Edge. 143 S-Label Service label. 145 T-PE Terminating Provider Edge. 147 TSN Time-Sensitive Network. 149 3. DetNet MPLS Data Plane Overview 151 The basic approach defined in [RFC8964] supports the DetNet service 152 sub-layer based on existing pseudowire (PW) encapsulations and 153 mechanisms, and supports the DetNet forwarding sub-layer based on 154 existing MPLS Traffic Engineering encapsulations and mechanisms. 156 A node operating on a DetNet flow in the Detnet service sub-layer, 157 i.e. a node processing a DetNet packet which has the S-Label as top 158 of stack uses the local context associated with that service label 159 (S-Label), for example a received forwarding label (F-Label), to 160 determine what local DetNet operation(s) are applied to that packet. 161 An S-Label may be unique when taken from the platform label space 162 [RFC3031], which would enable correct DetNet flow identification 163 regardless of which input interface or LSP the packet arrives on. 164 The service sub-layer functions (i.e., PREOF) use a DetNet control 165 word (d-CW). 167 The DetNet MPLS data plane builds on MPLS Traffic Engineering 168 encapsulations and mechanisms to provide a forwarding sub-layer that 169 is responsible for providing resource allocation and explicit routes. 170 The forwarding sub-layer is supported by one or more F-Labels. 172 DetNet edge/relay nodes are DetNet service sub-layer aware, 173 understand the particular needs of DetNet flows and provide both 174 DetNet service and forwarding sub-layer functions. They add, remove 175 and process d-CWs, S-Labels and F-labels as needed. MPLS DetNet 176 nodes and transit nodes include DetNet forwarding sub-layer 177 functions, support for notably explicit routes, and resources 178 allocation to eliminate (or reduce) congestion loss and jitter. 179 Unlike other DetNet node types, transit nodes provide no service sub- 180 layer processing. 182 MPLS (DetNet) nodes and transit nodes interconnected by a TSN sub- 183 network are the primary focus of this document. The mapping of 184 DetNet MPLS flows to TSN streams and TSN protection mechanisms are 185 covered in Section 4. 187 4. DetNet MPLS Operation Over IEEE 802.1 TSN Sub-Networks 189 The DetNet WG collaborates with IEEE 802.1 TSN in order to define a 190 common architecture for both Layer 2 and Layer 3, that maintains 191 consistency across diverse networks. Both DetNet MPLS and TSN use 192 the same techniques to provide their deterministic service: 194 o Service protection. 196 o Resource allocation. 198 o Explicit routes. 200 As described in the DetNet architecture [RFC8655] a sub-network 201 provides from MPLS perspective a single hop connection between MPLS 202 (DetNet) nodes. Functions used for resource allocation and explicit 203 routes are treated as domain internal functions and does not require 204 function interworking across the DetNet MPLS network and the TSN sub- 205 network. 207 In case of the service protection function due to the similarities of 208 the DetNet PREOF and TSN FRER functions some level of interworking is 209 possible. However, such interworking is out-of-scope in this 210 document and left for further study. 212 Figure 1 illustrates a scenario, where two MPLS (DetNet) nodes are 213 interconnected by a TSN sub-network. Node-1 is single homed and 214 Node-2 is dual-homed to the TSN sub-network. 216 MPLS (DetNet) MPLS (DetNet) 217 Node-1 Node-2 219 +----------+ +----------+ 220 <--| Service* |-- DetNet flow ---| Service* |--> 221 +----------+ +----------+ 222 |Forwarding| |Forwarding| 223 +--------.-+ <-TSN Str-> +-.-----.--+ 224 \ ,-------. / / 225 +----[ TSN-Sub ]---+ / 226 [ Network ]--------+ 227 `-------' 228 <---------------- DetNet MPLS ---------------> 230 Note: * no service sub-layer required for transit nodes 232 Figure 1: DetNet Enabled MPLS Network Over a TSN Sub-Network 234 The Time-Sensitive Networking (TSN) Task Group of the IEEE 802.1 235 Working Group have defined (and are defining) a number of amendments 236 to IEEE 802.1Q [IEEE8021Q] that provide zero congestion loss and 237 bounded latency in bridged networks. Furthermore IEEE 802.1CB 238 [IEEE8021CB] defines frame replication and elimination functions for 239 reliability that should prove both compatible with and useful to, 240 DetNet networks. All these functions have to identify flows those 241 require TSN treatment (i.e., applying TSN functions during 242 forwarding). 244 TSN capabilities of the TSN sub-network are made available for MPLS 245 (DetNet) flows via the protocol interworking function defined in 246 Annex C.5 of IEEE 802.1CB [IEEE8021CB]. For example, applied on the 247 TSN edge port it can convert an ingress unicast MPLS (DetNet) flow to 248 use a specific Layer-2 multicast destination MAC address and a VLAN, 249 in order to direct the packet through a specific path inside the 250 bridged network. A similar interworking function pair at the other 251 end of the TSN sub-network would restore the packet to its original 252 Layer-2 destination MAC address and VLAN. 254 Placement of TSN functions depends on the TSN capabilities of the 255 nodes along the path. MPLS (DetNet) Nodes may or may not support TSN 256 functions. For a given TSN Stream (i.e., DetNet flow) an MPLS 257 (DetNet) node is treated as a Talker or a Listener inside the TSN 258 sub-network. 260 4.1. Functions for DetNet Flow to TSN Stream Mapping 262 Mapping of a DetNet MPLS flow to a TSN Stream is provided via the 263 combination of a passive and an active stream identification function 264 that operate at the frame level. The passive stream identification 265 function is used to catch the MPLS label(s) of a DetNet MPLS flow and 266 the active stream identification function is used to modify the 267 Ethernet header according to the ID of the mapped TSN Stream. 269 Clause 6.8 of IEEE P802.1CBdb [IEEEP8021CBdb] defines a Mask-and- 270 Match Stream identification function that can be used as a passive 271 function for MPLS DetNet flows. 273 Clause 6.6 of IEEE 802.1CB [IEEE8021CB] defines an Active Destination 274 MAC and VLAN Stream identification function, what can replace some 275 Ethernet header fields namely (1) the destination MAC-address, (2) 276 the VLAN-ID and (3) priority parameters with alternate values. 277 Replacement is provided for the frame passed down the stack from the 278 upper layers or up the stack from the lower layers. 280 Active Destination MAC and VLAN Stream identification can be used 281 within a Talker to set flow identity or a Listener to recover the 282 original addressing information. It can be used also in a TSN bridge 283 that is providing translation as a proxy service for an End System. 285 4.2. TSN requirements of MPLS DetNet nodes 287 This section covers required behavior of a TSN-aware MPLS (DetNet) 288 node using a TSN sub-network. The implementation of TSN packet 289 processing functions must be compliant with the relevant IEEE 802.1 290 standards. 292 From the TSN sub-network perspective MPLS (DetNet) nodes are treated 293 as Talker or Listener, that may be (1) TSN-unaware or (2) TSN-aware. 295 In cases of TSN-unaware MPLS DetNet nodes the TSN relay nodes within 296 the TSN sub-network must modify the Ethernet encapsulation of the 297 DetNet MPLS flow (e.g., MAC translation, VLAN-ID setting, Sequence 298 number addition, etc.) to allow proper TSN specific handling inside 299 the sub-network. There are no requirements defined for TSN-unaware 300 MPLS DetNet nodes in this document. 302 MPLS (DetNet) nodes being TSN-aware can be treated as a combination 303 of a TSN-unaware Talker/Listener and a TSN-Relay, as shown in 304 Figure 2. In such cases the MPLS (DetNet) node must provide the TSN 305 sub-network specific Ethernet encapsulation over the link(s) towards 306 the sub-network. 308 MPLS (DetNet) 309 Node 310 <----------------------------------> 312 +----------+ 313 <--| Service* |-- DetNet flow ------------------ 314 +----------+ 315 |Forwarding| 316 +----------+ +---------------+ 317 | L2 | | L2 Relay with |<--- TSN --- 318 | | | TSN function | Stream 319 +-----.----+ +--.------.---.-+ 320 \__________/ \ \______ 321 \_________ 322 TSN-unaware 323 Talker / TSN-Bridge 324 Listener Relay 325 <----- TSN Sub-network ----- 326 <------- TSN-aware Tlk/Lstn -------> 328 Note: * no service sub-layer required for transit nodes 330 Figure 2: MPLS (DetNet) Node with TSN Functions 332 A TSN-aware MPLS (DetNet) node implementation must support the Stream 333 Identification TSN component for recognizing flows. 335 A Stream identification component must be able to instantiate the 336 following functions (1) Active Destination MAC and VLAN Stream 337 identification function, (2) Mask-and-Match Stream identification 338 function and (3) the related managed objects in Clause 9 of IEEE 339 802.1CB [IEEE8021CB] and IEEE P802.1CBdb [IEEEP8021CBdb]. 341 A TSN-aware MPLS (DetNet) node implementation must support the 342 Sequencing function and the Sequence encode/decode function as 343 defined in Clause 7.4 and 7.6 of IEEE 802.1CB [IEEE8021CB] if FRER is 344 used inside the TSN sub-network. 346 The Sequence encode/decode function must support the Redundancy tag 347 (R-TAG) format as per Clause 7.8 of IEEE 802.1CB [IEEE8021CB]. 349 A TSN-aware MPLS (DetNet) node implementation must support the Stream 350 splitting function and the Individual recovery function as defined in 351 Clause 7.7 and 7.5 of IEEE 802.1CB [IEEE8021CB] when the node is a 352 replication or elimination point for FRER. 354 4.3. Service protection within the TSN sub-network 356 TSN Streams supporting DetNet flows may use Frame Replication and 357 Elimination for Redundancy (FRER) as defined in Clause 8. of IEEE 358 802.1CB [IEEE8021CB] based on the loss service requirements of the 359 TSN Stream, which is derived from the DetNet service requirements of 360 the DetNet mapped flow. The specific operation of FRER is not 361 modified by the use of DetNet and follows IEEE 802.1CB [IEEE8021CB]. 363 FRER function and the provided service recovery is available only 364 within the TSN sub-network as the TSN Stream-ID and the TSN sequence 365 number are not valid outside the sub-network. An MPLS (DetNet) node 366 represents a L3 border and as such it terminates all related 367 information elements encoded in the L2 frames. 369 As the Stream-ID and the TSN sequence number are paired with the 370 similar MPLS flow parameters, FRER can be combined with PREOF 371 functions. Such service protection interworking scenarios may 372 require to move sequence number fields among TSN (L2) and PW (MPLS) 373 encapsulations and they are left for further study. 375 4.4. Aggregation during DetNet flow to TSN Stream mapping 377 Implementations of this document shall use management and control 378 information to map a DetNet flow to a TSN Stream. N:1 mapping 379 (aggregating DetNet flows in a single TSN Stream) shall be supported. 380 The management or control function that provisions flow mapping shall 381 ensure that adequate resources are allocated and configured to 382 provide proper service requirements of the mapped flows. 384 5. Management and Control Implications 386 DetNet flow and TSN Stream mapping related information are required 387 only for TSN-aware MPLS (DetNet) nodes. From the Data Plane 388 perspective there is no practical difference based on the origin of 389 flow mapping related information (management plane or control plane). 391 The following summarizes the set of information that is needed to 392 configure DetNet MPLS over TSN: 394 o DetNet MPLS related configuration information according to the 395 DetNet role of the DetNet MPLS node, as per [RFC8964]. 397 o TSN related configuration information according to the TSN role of 398 the DetNet MPLS node, as per [IEEE8021Q], [IEEE8021CB] and 399 [IEEEP8021CBdb]. 401 o Mapping between DetNet MPLS flow(s) (label information: A-labels, 402 S-labels and F-labels as defined in [RFC8964]) and TSN Stream(s) 403 (as stream identification information defined in [IEEEP8021CBdb]). 404 Note, that managed objects for TSN Stream identification can be 405 found in [IEEEP8021CBcv]. 407 This information must be provisioned per DetNet flow. 409 Mappings between DetNet and TSN management and control planes are out 410 of scope of the document. Some of the challenges are highlighted 411 below. 413 TSN-aware MPLS DetNet nodes are member of both the DetNet domain and 414 the TSN sub-network. Within the TSN sub-network the TSN-aware MPLS 415 (DetNet) node has a TSN-aware Talker/Listener role, so TSN specific 416 management and control plane functionalities must be implemented. 417 There are many similarities in the management plane techniques used 418 in DetNet and TSN, but that is not the case for the control plane 419 protocols. For example, RSVP-TE and MSRP behaves differently. 420 Therefore management and control plane design is an important aspect 421 of scenarios, where mapping between DetNet and TSN is required. 423 In order to use a TSN sub-network between DetNet nodes, DetNet 424 specific information must be converted to TSN sub-network specific 425 ones. DetNet flow ID and flow related parameters/requirements must 426 be converted to a TSN Stream ID and stream related parameters/ 427 requirements. Note that, as the TSN sub-network is just a portion of 428 the end2end DetNet path (i.e., single hop from MPLS perspective), 429 some parameters (e.g., delay) may differ significantly. Other 430 parameters (like bandwidth) also may have to be tuned due to the L2 431 encapsulation used within the TSN sub-network. 433 In some case it may be challenging to determine some TSN Stream 434 related information. For example, on a TSN-aware MPLS (DetNet) node 435 that acts as a Talker, it is quite obvious which DetNet node is the 436 Listener of the mapped TSN stream (i.e., the MPLS Next-Hop). However 437 it may be not trivial to locate the point/interface where that 438 Listener is connected to the TSN sub-network. Such attributes may 439 require interaction between control and management plane functions 440 and between DetNet and TSN domains. 442 Mapping between DetNet flow identifiers and TSN Stream identifiers, 443 if not provided explicitly, can be done by a TSN-aware MPLS (DetNet) 444 node locally based on information provided for configuration of the 445 TSN Stream identification functions (Mask-and-match Stream 446 identification and Active Stream identification function). 448 Triggering the setup/modification of a TSN Stream in the TSN sub- 449 network is an example where management and/or control plane 450 interactions are required between the DetNet and TSN sub-network. 451 TSN-unaware MPLS (DetNet) nodes make such a triggering even more 452 complicated as they are fully unaware of the sub-network and run 453 independently. 455 Configuration of TSN specific functions (e.g., FRER) inside the TSN 456 sub-network is a TSN domain specific decision and may not be visible 457 in the DetNet domain. Service protection interworking scenarios are 458 left for further study. 460 6. Security Considerations 462 Security considerations for DetNet are described in detail in 463 [I-D.ietf-detnet-security]. General security considerations are 464 described in [RFC8655]. DetNet MPLS data plane specific 465 considerations are summarized in [RFC8964]. This section considers 466 exclusively security considerations which are specific to the DetNet 467 MPLS over TSN sub-network scenario. 469 The sub-network between DetNet nodes needs to be subject to 470 appropriate confidentiality. Additionally, knowledge of what DetNet/ 471 TSN services are provided by a sub-network may supply information 472 that can be used in a variety of security attacks. The ability to 473 modify information exchanges between connected DetNet nodes may 474 result in bogus operations. Therefore, it is important that the 475 interface between DetNet nodes and TSN sub-network are subject to 476 authorization, authentication, and encryption. 478 The TSN sub-network operates at Layer-2 so various security 479 mechanisms defined by IEEE can be used to secure the connection 480 between the DetNet nodes (e.g., encryption may be provided using 481 MACSec [IEEE802.1AE-2018]). 483 7. IANA Considerations 485 This document makes no IANA requests. 487 8. Acknowledgements 489 The authors wish to thank Norman Finn, Lou Berger, Craig Gunther, 490 Christophe Mangin and Jouni Korhonen for their various contributions 491 to this work. 493 9. References 495 9.1. Normative References 497 [IEEE8021CB] 498 IEEE 802.1, "Standard for Local and metropolitan area 499 networks - Frame Replication and Elimination for 500 Reliability (IEEE Std 802.1CB-2017)", 2017, 501 . 503 [IEEEP8021CBdb] 504 Mangin, C., "Extended Stream identification functions", 505 IEEE P802.1CBdb /D1.0 P802.1CBdb, September 2020, 506 . 509 [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol 510 Label Switching Architecture", RFC 3031, 511 DOI 10.17487/RFC3031, January 2001, 512 . 514 [RFC8964] Varga, B., Ed., Farkas, J., Berger, L., Malis, A., Bryant, 515 S., and J. Korhonen, "Deterministic Networking (DetNet) 516 Data Plane: MPLS", RFC 8964, DOI 10.17487/RFC8964, January 517 2021, . 519 9.2. Informative References 521 [I-D.ietf-detnet-security] 522 Grossman, E., Mizrahi, T., and A. Hacker, "Deterministic 523 Networking (DetNet) Security Considerations", draft-ietf- 524 detnet-security-13 (work in progress), December 2020. 526 [IEEE802.1AE-2018] 527 IEEE Standards Association, "IEEE Std 802.1AE-2018 MAC 528 Security (MACsec)", 2018, 529 . 531 [IEEE8021Q] 532 IEEE 802.1, "Standard for Local and metropolitan area 533 networks--Bridges and Bridged Networks (IEEE Std 802.1Q- 534 2018)", 2018, . 536 [IEEEP8021CBcv] 537 Kehrer, S., "FRER YANG Data Model and Management 538 Information Base Module", IEEE P802.1CBcv 539 /D0.4 P802.1CBcv, August 2020, 540 . 543 [RFC8655] Finn, N., Thubert, P., Varga, B., and J. Farkas, 544 "Deterministic Networking Architecture", RFC 8655, 545 DOI 10.17487/RFC8655, October 2019, 546 . 548 Authors' Addresses 550 Balazs Varga (editor) 551 Ericsson 552 Magyar Tudosok krt. 11. 553 Budapest 1117 554 Hungary 556 Email: balazs.a.varga@ericsson.com 558 Janos Farkas 559 Ericsson 560 Magyar Tudosok krt. 11. 561 Budapest 1117 562 Hungary 564 Email: janos.farkas@ericsson.com 566 Andrew G. Malis 567 Malis Consulting 569 Email: agmalis@gmail.com 571 Stewart Bryant 572 Futurewei Technologies 574 Email: stewart.bryant@gmail.com