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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: Standards Track Ericsson 5 Expires: March 14, 2021 L. Berger 6 LabN Consulting, L.L.C. 7 A. Malis 8 Malis Consulting 9 S. Bryant 10 Futurewei Technologies 11 J. Korhonen 12 September 10, 2020 14 DetNet Data Plane: MPLS 15 draft-ietf-detnet-mpls-12 17 Abstract 19 This document specifies the Deterministic Networking data plane when 20 operating over an MPLS Packet Switched Network. It leverages 21 existing pseudowire (PW) encapsulations and MPLS Traffic Engineering 22 encapsulations and mechanisms. This document builds on the DetNet 23 Architecture and Data Plane Framework. 25 Status of This Memo 27 This Internet-Draft is submitted in full conformance with the 28 provisions of BCP 78 and BCP 79. 30 Internet-Drafts are working documents of the Internet Engineering 31 Task Force (IETF). Note that other groups may also distribute 32 working documents as Internet-Drafts. The list of current Internet- 33 Drafts is at https://datatracker.ietf.org/drafts/current/. 35 Internet-Drafts are draft documents valid for a maximum of six months 36 and may be updated, replaced, or obsoleted by other documents at any 37 time. It is inappropriate to use Internet-Drafts as reference 38 material or to cite them other than as "work in progress." 40 This Internet-Draft will expire on March 14, 2021. 42 Copyright Notice 44 Copyright (c) 2020 IETF Trust and the persons identified as the 45 document authors. All rights reserved. 47 This document is subject to BCP 78 and the IETF Trust's Legal 48 Provisions Relating to IETF Documents 49 (https://trustee.ietf.org/license-info) in effect on the date of 50 publication of this document. Please review these documents 51 carefully, as they describe your rights and restrictions with respect 52 to this document. Code Components extracted from this document must 53 include Simplified BSD License text as described in Section 4.e of 54 the Trust Legal Provisions and are provided without warranty as 55 described in the Simplified BSD License. 57 Table of Contents 59 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 60 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 61 2.1. Terms Used in This Document . . . . . . . . . . . . . . . 3 62 2.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 4 63 2.3. Requirements Language . . . . . . . . . . . . . . . . . . 5 64 3. DetNet MPLS Data Plane Overview . . . . . . . . . . . . . . . 5 65 3.1. Layers of DetNet Data Plane . . . . . . . . . . . . . . . 5 66 3.2. DetNet MPLS Data Plane Scenarios . . . . . . . . . . . . 6 67 4. MPLS-Based DetNet Data Plane Solution . . . . . . . . . . . . 8 68 4.1. DetNet Over MPLS Encapsulation Components . . . . . . . . 8 69 4.2. MPLS Data Plane Encapsulation . . . . . . . . . . . . . . 9 70 4.2.1. DetNet Control Word and the DetNet Sequence Number . 10 71 4.2.2. S-Labels . . . . . . . . . . . . . . . . . . . . . . 11 72 4.2.3. F-Labels . . . . . . . . . . . . . . . . . . . . . . 14 73 4.3. OAM Indication . . . . . . . . . . . . . . . . . . . . . 17 74 4.4. Flow Aggregation . . . . . . . . . . . . . . . . . . . . 17 75 4.4.1. Aggregation Via LSP Hierarchy . . . . . . . . . . . . 17 76 4.4.2. Aggregating DetNet Flows as a new DetNet flow . . . . 18 77 4.5. Service Sub-Layer Considerations . . . . . . . . . . . . 19 78 4.5.1. Edge Node Processing . . . . . . . . . . . . . . . . 19 79 4.5.2. Relay Node Processing . . . . . . . . . . . . . . . . 20 80 4.6. Forwarding Sub-Layer Considerations . . . . . . . . . . . 20 81 4.6.1. Class of Service . . . . . . . . . . . . . . . . . . 20 82 4.6.2. Quality of Service . . . . . . . . . . . . . . . . . 21 83 5. Management and Control Information Summary . . . . . . . . . 21 84 5.1. Service Sub-Layer Information Summary . . . . . . . . . . 22 85 5.1.1. Service Aggregation Information Summary . . . . . . . 23 86 5.2. Forwarding Sub-Layer Information Summary . . . . . . . . 23 87 6. Security Considerations . . . . . . . . . . . . . . . . . . . 24 88 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25 89 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 25 90 9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 26 91 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 26 92 10.1. Normative References . . . . . . . . . . . . . . . . . . 26 93 10.2. Informative References . . . . . . . . . . . . . . . . . 28 94 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 30 96 1. Introduction 98 Deterministic Networking (DetNet) is a service that can be offered by 99 a network to DetNet flows. DetNet provides a capability for the 100 delivery of data flows with extremely low packet loss rates and 101 bounded end-to-end delivery latency. General background and concepts 102 of DetNet can be found in the DetNet Architecture [RFC8655]. 104 The DetNet Architecture models the DetNet related data plane 105 functions decomposed into two sub-layers: a service sub-layer and a 106 forwarding sub-layer. The service sub-layer is used to provide 107 DetNet service functions such as protection and reordering. The 108 forwarding sub-layer is used to provide forwarding assurance (low 109 loss, assured latency, and limited out-of-order delivery). 111 This document specifies the DetNet data plane operation and the on- 112 wire encapsulation of DetNet flows over an MPLS-based Packet Switched 113 Network (PSN) using the service reference model. MPLS encapsulation 114 already provides a solid foundation of building blocks to enable the 115 DetNet service and forwarding sub-layer functions. MPLS encapsulated 116 DetNet can be carried over a variety of different network 117 technologies that can provide the DetNet required level of service. 118 However, the specific details of how DetNet MPLS is carried over 119 different network technologies are out of scope of this document. 121 MPLS encapsulated DetNet flows can carry different types of traffic. 122 The details of the types of traffic that are carried in DetNet are 123 also out of scope of this document. An example of IP using DetNet 124 MPLS sub-networks can be found in [I-D.ietf-detnet-ip]. DetNet MPLS 125 may use an associated controller and Operations, Administration, and 126 Maintenance (OAM) functions that are defined outside of this 127 document. 129 Background information common to all data planes for DetNet can be 130 found in the DetNet Data Plane Framework 131 [I-D.ietf-detnet-data-plane-framework]. 133 2. Terminology 135 2.1. Terms Used in This Document 137 This document uses the terminology established in the DetNet 138 architecture [RFC8655] and the DetNet Data Plane Framework 139 [I-D.ietf-detnet-data-plane-framework]. The reader is assumed to be 140 familiar with these documents, any terminology defined therein and 141 basic MPLS related terminologies in [RFC3031]. 143 The following terminology is introduced in this document: 145 F-Label A Detnet "forwarding" label that identifies the LSP 146 used to forward a DetNet flow across an MPLS PSN, e.g., 147 a hop-by-hop label used between label switching routers 148 (LSR). 150 S-Label A DetNet "service" label that is used between DetNet 151 nodes that implement the DetNet service sub-layer 152 functions. An S-Label is used to identify a DetNet 153 flow at DetNet service sub-layer at a receiving DetNet 154 node. 156 A-Label A special case of an S-Label, whose aggregation 157 properties are known only at the aggregation and 158 deaggregation end-points. 160 d-CW A DetNet Control Word (d-CW) is used for sequencing 161 information of a DetNet flow at the DetNet service sub- 162 layer. 164 2.2. Abbreviations 166 The following abbreviations are used in this document: 168 CoS Class of Service. 170 CW Control Word. 172 DetNet Deterministic Networking. 174 LSR Label Switching Router. 176 MPLS Multiprotocol Label Switching. 178 MPLS-TE Multiprotocol Label Switching - Traffic Engineering. 180 MPLS-TP Multiprotocol Label Switching - Transport Profile. 182 OAM Operations, Administration, and Maintenance. 184 PE Provider Edge. 186 PEF Packet Elimination Function. 188 PRF Packet Replication Function. 190 PREOF Packet Replication, Elimination and Ordering Functions. 192 POF Packet Ordering Function. 194 PSN Packet Switched Network. 196 PW PseudoWire. 198 QoS Quality of Service. 200 S-PE Switching Provider Edge. 202 T-PE Terminating Provider Edge. 204 TSN Time-Sensitive Network. 206 2.3. Requirements Language 208 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 209 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 210 "OPTIONAL" in this document are to be interpreted as described in BCP 211 14 [RFC2119] [RFC8174] when, and only when, they appear in all 212 capitals, as shown here. 214 3. DetNet MPLS Data Plane Overview 216 3.1. Layers of DetNet Data Plane 218 MPLS provides a wide range of capabilities that can be utilised by 219 DetNet. A straight forward approach utilizing MPLS for a DetNet 220 service sub-layer is based on the existing pseudowire (PW) 221 encapsulations and by utilizing existing MPLS Traffic Engineering 222 encapsulations and mechanisms. Background on PWs can be found in 223 [RFC3985] and [RFC3031]. Background on MPLS Traffic Engineering can 224 be found in [RFC3272] and [RFC3209]. 226 DetNet MPLS 227 . 228 Bottom of Stack . 229 (inner label) +------------+ 230 | Service | d-CW, S-Label (A-Label) 231 +------------+ 232 | Forwarding | F-Label(s) 233 +------------+ 234 Top of Stack . 235 (outer label) . 237 Figure 1: DetNet Adaptation to MPLS Data Plane 239 The DetNet MPLS data plane representation is illustrated in Figure 1. 240 The service sub-layer includes a DetNet control word (d-CW) and an 241 identifying service label (S-Label). The DetNet control word (d-CW) 242 conforms to the Generic PW MPLS Control Word (PWMCW) defined in 243 [RFC4385]. An aggregation label (A-Label) is a special case of 244 S-Label used for aggregation. 246 A node operating on a received DetNet flow at the Detnet service sub- 247 layer uses the local context associated with a received S-Label, 248 i.e., a received F-Label, to determine which local DetNet 249 operation(s) are applied to that packet. An S-Label may be taken 250 from the platform label space [RFC3031], making it unique, enabling 251 DetNet flow identification regardless of which input interface or LSP 252 the packet arrives on. It is important to note that S-Label values 253 are driven by the receiver, not the sender. 255 The DetNet forwarding sub-layer is supported by zero or more 256 forwarding labels (F-Labels). MPLS Traffic Engineering 257 encapsulations and mechanisms can be utilized to provide a forwarding 258 sub-layer that is responsible for providing resource allocation and 259 explicit routes. 261 3.2. DetNet MPLS Data Plane Scenarios 263 DetNet MPLS Relay Transit Relay DetNet MPLS 264 End System Node Node Node End System 265 (T-PE) (S-PE) (LSR) (S-PE) (T-PE) 266 +----------+ +----------+ 267 | Appl. |<------------ End to End Service ----------->| Appl. | 268 +----------+ +---------+ +---------+ +----------+ 269 | Service |<--| Service |-- DetNet flow --| Service |-->| Service | 270 +----------+ +---------+ +----------+ +---------+ +----------+ 271 |Forwarding| |Fwd| |Fwd| |Forwarding| |Fwd| |Fwd| |Forwarding| 272 +-------.--+ +-.-+ +-.-+ +----.---.-+ +-.-+ +-.-+ +---.------+ 273 : Link : / ,-----. \ : Link : / ,-----. \ 274 +........+ +-[ Sub ]-+ +......+ +-[ Sub ]-+ 275 [Network] [Network] 276 `-----' `-----' 277 |<- LSP -->| |<-------- LSP -----------| |<--- LSP -->| 279 |<----------------- DetNet MPLS --------------------->| 281 Figure 2: A DetNet MPLS Network 283 Figure 2 illustrates a hypothetical DetNet MPLS-only network composed 284 of DetNet aware MPLS enabled end systems, operating over a DetNet 285 aware MPLS network. In this figure, the relay nodes are PE devices 286 that define the MPLS LSP boundaries and the transit nodes are LSRs. 288 DetNet end systems and relay nodes understand the particular needs of 289 DetNet flows and provide both DetNet service and forwarding sub-layer 290 functions. In the case of MPLS, DetNet service-aware nodes add, 291 remove and process d-CWs, S-Labels and F-labels as needed. DetNet 292 MPLS nodes provide functionality analogous to T-PEs when they sit at 293 the edge of an MPLS domain, and S-PEs when they are in the middle of 294 an MPLS domain, see [RFC6073]. 296 In a DetNet MPLS network, transit nodes may be DetNet service aware 297 or may be DetNet unaware MPLS Label Switching Routers (LSRs). In 298 this latter case, such LSRs would be unaware of the special 299 requirements of the DetNet service sub-layer, but would still provide 300 traffic engineering functions and the QoS capabilities needed to 301 ensure that the (TE) LSPs meet the service requirements of the 302 carried DetNet flows. 304 The application of DetNet using MPLS supports a number of control 305 plane/management plane types. These types support certain MPLS data 306 plane deployments. For example RSVP-TE, MPLS-TP, or MPLS Segment 307 Routing (when extended to support resource allocation) are all valid 308 MPLS deployment cases. 310 Figure 3 illustrates how an end-to-end MPLS-based DetNet service is 311 provided in a more detail. In this figure, the customer end systems, 312 CE1 and CE2, are able to send and receive MPLS encapsulated DetNet 313 flows, and R1, R2 and R3 are relay nodes in the middle of a DetNet 314 network. The 'X' in the end systems, and relay nodes represents 315 potential DetNet compound flow packet replication and elimination 316 points. In this example, service protection is supported utilizing 317 at least two DetNet member flows and TE LSPs. For a unidirectional 318 flow, R1 supports PRF and R3 supports PEF and POF. Note that the 319 relay nodes may change the underlying forwarding sub-layer, for 320 example tunneling MPLS over IEEE 802.1 TSN 321 [I-D.ietf-detnet-mpls-over-tsn], or simply over interconnect network 322 links. 324 DetNet DetNet 325 DetNet Service Transit Transit Service DetNet 326 MPLS | |<-Tnl->| |<-Tnl->| | MPLS 327 End | V 1 V V 2 V | End 328 System | +--------+ +--------+ +--------+ | System 329 +---+ | | R1 |=======| R2 |=======| R3 | | +---+ 330 | X...DFa...|._X_....|..DF1..|.__ ___.|..DF3..|...._X_.|.DFa..|.X | 331 |CE1|========| \ | | X | | / |======|CE2| 332 | | | | \_.|..DF2..|._/ \__.|..DF4..|._/ | | | | 333 +---+ | |=======| |=======| | +---+ 334 ^ +--------+ +--------+ +--------+ ^ 335 | Relay Node Relay Node Relay Node | 336 | (S-PE) (S-PE) (S-PE) | 337 | | 338 |<---------------------- DetNet MPLS --------------------->| 339 | | 340 |<--------------- End to End DetNet Service -------------->| 342 -------------------------- Data Flow -------------------------> 344 X = Optional service protection (none, PRF, PREOF, PEF/POF) 345 DFx = DetNet member flow x over a TE LSP 347 Figure 3: MPLS-Based Native DetNet 349 4. MPLS-Based DetNet Data Plane Solution 351 4.1. DetNet Over MPLS Encapsulation Components 353 To carry DetNet over MPLS the following is required: 355 1. A method of identifying the MPLS payload type. 357 2. A method of identifying the DetNet flow(s) to the processing 358 element. 360 3. A method of distinguishing DetNet OAM packets from DetNet data 361 packets. 363 4. A method of carrying the DetNet sequence number. 365 5. A suitable LSP to deliver the packet to the egress PE. 367 6. A method of carrying queuing and forwarding indication. 369 In this design an MPLS service label (the S-Label), is similar to a 370 pseudowire (PW) label [RFC3985], and is used to identify both the 371 DetNet flow identity and the payload MPLS payload type satisfying (1) 372 and (2) in the list above. OAM traffic discrimination happens 373 through the use of the Associated Channel method described in 374 [RFC4385]. The DetNet sequence number is carried in the DetNet 375 Control word which carries the Data/OAM discriminator. To simplify 376 implementation and to maximize interoperability two sequence number 377 sizes are supported: a 16 bit sequence number and a 28 bit sequence 378 number. The 16 bit sequence number is needed to support some types 379 of legacy clients. The 28 bit sequence number is used in situations 380 where it is necessary ensure that in high speed networks the sequence 381 number space does not wrap whilst packets are in flight. 383 The LSP used to forward the DetNet packet is not restricted regarding 384 any method used for establishing that LSP (for example, MPLS-LDP, 385 MPLS-TE, MPLS-TP [RFC5921], MPLS-SR [RFC8660], etc.). The LSP 386 (F-Label) label(s) and/or the S-Label may be used to indicate the 387 required queue processing as well as the forwarding parameters. Note 388 that the possible use of Penultimate Hop Popping (PHP) means that the 389 S-Label may be the only label received at the terminating DetNet 390 service. 392 4.2. MPLS Data Plane Encapsulation 394 Figure 4 illustrates a DetNet data plane MPLS encapsulation. The 395 MPLS-based encapsulation of the DetNet flows is well suited for the 396 scenarios described in [I-D.ietf-detnet-data-plane-framework]. 397 Furthermore, an end-to-end DetNet service i.e., native DetNet 398 deployment (see Section 3.2) is also possible if DetNet end systems 399 are capable of initiating and termination MPLS encapsulated packets. 401 The MPLS-based DetNet data plane encapsulation consists of: 403 o DetNet control word (d-CW) containing sequencing information for 404 packet replication and duplicate elimination purposes, and the OAM 405 indicator. 407 o DetNet service Label (S-Label) that identifies a DetNet flow at 408 the receiving DetNet service sub-layer processing node. 410 o Zero or more Detnet MPLS Forwarding label(s) (F-Label) used to 411 direct the packet along the label switched path (LSP) to the next 412 DetNet service sub-layer processing node along the path. When 413 Penultimate Hop Popping is in use there may be no label F-Label in 414 the protocol stack on the final hop. 416 o The necessary data-link encapsulation is then applied prior to 417 transmission over the physical media. 419 DetNet MPLS-based encapsulation 421 +---------------------------------+ 422 | | 423 | DetNet App-Flow | 424 | Payload Packet | 425 | | 426 +---------------------------------+ <--\ 427 | DetNet Control Word | | 428 +---------------------------------+ +--> DetNet data plane 429 | S-Label | | MPLS encapsulation 430 +---------------------------------+ | 431 | [ F-Label(s) ] | | 432 +---------------------------------+ <--/ 433 | Data-Link | 434 +---------------------------------+ 435 | Physical | 436 +---------------------------------+ 438 Figure 4: Encapsulation of a DetNet App-Flow in an MPLS PSN 440 4.2.1. DetNet Control Word and the DetNet Sequence Number 442 A DetNet control word (d-CW) conforms to the Generic PW MPLS Control 443 Word (PWMCW) defined in [RFC4385]. The d-CW formatted as shown in 444 Figure 5 MUST be present in all DetNet packets containing app-flow 445 data. This format of the d-CW was created in order (1) to allow 446 larger sequence number space to avoid sequence number rollover 447 frequency in some applications and (2) to allow sequence numbering 448 systems that include the value zero as a valid sequence number, which 449 simplifies implementation. 451 0 1 2 3 452 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 1 453 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 454 |0 0 0 0| Sequence Number | 455 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 457 Figure 5: DetNet Control Word 459 (bits 0 to 3) 461 Per [RFC4385], MUST be set to zero (0). 463 Sequence Number (bits 4 to 31) 464 An unsigned value implementing the DetNet sequence number. The 465 sequence number space is a circular one with no restriction on 466 initial value. 468 A separate sequence number space MUST be maintained by the node that 469 adds the d-CW for each DetNet app-flow, i.e., DetNet service. The 470 following sequence number field lengths MUST be supported: 472 0 bits 474 16 bits 476 28 bits 478 The sequence number length MUST be provisioned on a per Detnet 479 service basis via configuration, i.e., via the controller plane 480 described in [I-D.ietf-detnet-data-plane-framework]. 482 A 0 bit sequence number field length indicates that there is no 483 DetNet sequence number used for the flow. When the length is zero, 484 the sequence number field MUST be set to zero (0) on all packets sent 485 for the flow. 487 When the sequence number field length is 16 or 28 bits for a flow, 488 the sequence number MUST be incremented by one for each new app-flow 489 packet sent. When the field length is 16 bits, d-CW bits 4 to 15 490 MUST be set to zero (0). The values carried in this field can wrap 491 and it is important to note that zero (0) is a valid field value. 492 For example, where the sequence number size is 16 bits, the sequence 493 will contain: 65535, 0, 1, where zero (0) is an ordinary sequence 494 number. 496 It is important to note that this document differs from [RFC4448] 497 where a sequence number of zero (0) is used to indicate that the 498 sequence number check algorithm is not used. 500 The sequence number is optionally used during receive processing as 501 described below in Section 4.2.2.2 and Section 4.2.2.3. 503 4.2.2. S-Labels 505 A DetNet flow at the DetNet service sub-layer is identified by an 506 S-Label. MPLS-aware DetNet end systems and edge nodes, which are by 507 definition MPLS ingress and egress nodes, MUST add (push) and remove 508 (pop) a DetNet service-specific d-CW and S-Label. Relay nodes MAY 509 swap S-Label values when processing a DetNet flow, i.e., incoming and 510 outgoing S-Labels of a DetNet flow can be different. 512 S-Label values MUST be provisioned per DetNet service via 513 configuration, e.g., via the controller plane described in 514 [I-D.ietf-detnet-data-plane-framework]. Note that S-Labels provide 515 identification at the downstream DetNet service sub-layer receiver, 516 not the sender. As such, S-Labels MUST be allocated by the entity 517 that controls the service sub-layer receiving node's label space, and 518 MAY be allocated from the platform label space [RFC3031]. Because 519 S-Labels are local to each node rather than being a global identifier 520 within a domain, they must be advertised to their upstream DetNet 521 service-aware peer nodes (e.g., a DetNet MPLS End System or a DetNet 522 Relay or Edge Node) and interpreted in the context of their received 523 F-Label(s). In some PREOF topologies, the node performing 524 replication will be sending to multiple nodes performing PEF or POF, 525 and may need to send different S-Label values for the different 526 member flows for the same DetNet service. 528 An S-Label will normally be at the bottom of the label stack once the 529 last F-Label is removed, immediately preceding the d-CW. To support 530 service sub-layer level OAM, an OAM Associated Channel Header (ACH) 531 [RFC4385] together with a Generic Associated Channel Label (GAL) 532 [RFC5586] MAY be used in place of a d-CW. 534 Similarly, an Entropy Label Indicator/Entropy Label (ELI/EL) 535 [RFC6790] MAY be carried below the S-Label in the label stack in 536 networks where DetNet flows would otherwise receive ECMP treatment. 537 When ELs are used, the same EL value SHOULD be used for all of the 538 packets sent using a specific S-Label to force the flow to follow the 539 same path. However, as outlined in 540 [I-D.ietf-detnet-data-plane-framework] the use of ECMP for DetNet 541 flows is NOT RECOMMENDED. ECMP MAY be used for non-DetNet flows 542 within a DetNet domain. 544 When receiving a DetNet MPLS packet, an implementation MUST identify 545 the DetNet service associated with the incoming packet based on the 546 S-Label. When a node is using platform labels for S-Labels, no 547 additional information is needed as the S-label uniquely identifies 548 the DetNet service. In the case where platform labels are not used, 549 zero or more F-Labels proceeding the S-Label MUST be used together 550 with the S-Label to uniquely identify the DetNet service associated 551 with a received packet. The incoming interface MAY also be used 552 together with any present F-Label(s) and the S-Label to uniquely 553 identify an incoming DetNet service, for example, in the case where 554 PHP is used. Note that choice to use platform label space for 555 S-Label or S-Label plus one or more F-Labels to identify DetNet 556 services is a local implementation choice, with one caveat. When one 557 or more F-labels, or incoming interface, is needed together with an 558 S-Label to uniquely identify a service, the controller plane must 559 ensure that incoming DetNet MPLS packets arrive with the needed 560 information (F-label(s) and/or incoming interface) and provision the 561 needed information. The provisioned information MUST then be used to 562 identify incoming DetNet service based on the combination of S-Label 563 and F-Label(s) or incoming interface. 565 The use of platform labels for S-Labels matches other pseudowire 566 encapsulations for consistency but there is no hard requirement in 567 this regard. 569 4.2.2.1. Packet Replication Function Processing 571 The Packet Replication Function (PRF) function MAY be supported by an 572 implementation for outgoing DetNet flows. The use of the PRF for a 573 particular DetNet service MUST be provisioned via configuration, 574 e.g., via the controller plane described in 575 [I-D.ietf-detnet-data-plane-framework]. When replication is 576 configured, the same app-flow data will be sent over multiple 577 outgoing DetNet member flows using forwarding sub-layer LSPs. An 578 S-Label value MUST be configured per outgoing member flow. The same 579 d-CW field value MUST be used on all outgoing member flows for each 580 replicated MPLS packet. 582 4.2.2.2. Packet Elimination Function Processing 584 Implementations MAY support the Packet Elimination Function (PEF) for 585 received DetNet MPLS flows. When supported, use of the PEF for a 586 particular DetNet service MUST be provisioned via configuration, 587 e.g., via the controller plane described in 588 [I-D.ietf-detnet-data-plane-framework]. 590 After a DetNet service is identified for a received DetNet MPLS 591 packet, as described above, if PEF is configured for that DetNet 592 service, duplicate (replicated) instances of a particular sequence 593 number MUST be discarded. The specific mechanisms used for an 594 implementation to identify which received packets are duplicates and 595 which are new is an implementation choice. Note that per 596 Section 4.2.1 the sequence number field length may be 16 or 28 bits, 597 and the field value can wrap. PEF MUST NOT be used with DetNet flows 598 configured with a d-CW sequence number field length of 0 bits. 600 An implementation MAY constrain the maximum number of sequence 601 numbers that are tracked on either a platform-wide or per flow basis. 602 Some implementations MAY support the provisioning of the maximum 603 number of sequence numbers that are tracked on either a platform-wide 604 or per flow basis. 606 4.2.2.3. Packet Ordering Function Processing 608 A function that is related to in-order delivery is the Packet 609 Ordering Function (POF). Implementations MAY support POF. When 610 supported, use of the POF for a particular DetNet service MUST be 611 provisioned via configuration, e.g., via the controller plane 612 described by [I-D.ietf-detnet-data-plane-framework]. Implementations 613 MAY require that PEF and POF be used in combination. There is no 614 requirement related to the order of execution of the Packet 615 Elimination and Ordering Functions in an implementation. 617 After a DetNet service is identified for a received DetNet MPLS 618 packet, as described above, if POF is configured for that DetNet 619 service, packets MUST be processed in the order indicated in the 620 received d-CW sequence number field, which may not be in the order 621 the packets are received. As defined in Section 4.2.1 the sequence 622 number field length may be 16 or 28 bits, is incremented by one (1) 623 for each new MPLS packet sent for a particular DetNet service, and 624 the field value can wrap. The specific mechanisms used for an 625 implementation to identify the order of received packets is an 626 implementation choice. 628 An implementation MAY constrain the maximum number of out of order 629 packets that can be processed, on either a platform-wide or per flow 630 basis. The number of out of order packets that can be processed also 631 impacts the latency of a flow. 633 4.2.3. F-Labels 635 F-Labels support the DetNet forwarding sub-layer. F-Labels are used 636 to provide LSP-based connectivity between DetNet service sub-layer 637 processing nodes. 639 4.2.3.1. Service Sub-Layer Related Processing 641 DetNet MPLS end systems, edge nodes and relay nodes may operate at 642 the DetNet service sub-layer with understanding of DetNet services 643 and their requirements. As mentioned earlier, when operating at this 644 layer such nodes can push, pop or swap (pop then push) S-Labels. In 645 all cases, the F-Label(s) used for a DetNet service are always 646 replaced and the following procedures apply. 648 When sending a DetNet flow, zero or more F-Labels MAY be pushed on 649 top of an S-Label by the node pushing an S-Label. The F-Label(s) to 650 be pushed when sending a particular DetNet service MUST be 651 provisioned per outgoing S-Label via configuration, e.g., via the 652 controller plane discussed in [I-D.ietf-detnet-data-plane-framework]. 653 F-Label(s) can also provide context for an S-Label. To allow for the 654 omission of F-Label(s), an implementation SHOULD also allow an 655 outgoing interface to be configured per S-Label. 657 Note, when PRF is supported, the same app-flow data will be sent over 658 multiple outgoing DetNet member flows using forwarding sub-layer 659 LSPs. This means that implementation may be sending different sets 660 of F-Labels per DetNet member flow, each with a different S-Label. 662 When a single set of F-Labels is provisioned for a particular 663 outgoing S-Label, that set of F-labels MUST be pushed after the 664 S-Label is pushed. The outgoing packet is then forwarded as 665 described below in Section 4.2.3.2. When a single outgoing interface 666 is provisioned, the outgoing packet is then forwarded as described 667 below in Section 4.2.3.2. 669 When multiple sets of outgoing F-Labels or interfaces are provisioned 670 for a particular DetNet service (i.e., for PRF), a copy of the 671 outgoing packet, including the pushed member flow-specific S-Label, 672 MUST be made per F-label set and outgoing interface. Each set of 673 provisioned F-Labels are then pushed onto a copy of the packet. Each 674 copy is then forwarded as described below in Section 4.2.3.2. 676 As described in the previous section, when receiving a DetNet MPLS 677 flow, an implementation identifies the DetNet service associated with 678 the incoming packet based on the S-Label. When a node is using 679 platform labels for S-Labels, any F-Labels can be popped and the 680 S-label uniquely identifies the DetNet service. In the case where 681 platform labels are not used, incoming F-Label(s) and, optionally, 682 the incoming interface MUST also be provisioned for a DetNet service. 684 4.2.3.2. Common F-Label Processing 686 All DetNet aware MPLS nodes process F-Labels as needed to meet the 687 service requirements of the DetNet flow or flows carried in the LSPs 688 represented by the F-Labels. This includes normal push, pop and swap 689 operations. Such processing is essentially the same type of 690 processing provided for TE LSPs, although the specific service 691 parameters, or traffic specification, can differ. When the DetNet 692 service parameters of the DetNet flow or flows carried in an LSP 693 represented by an F-Label can be met by an existing TE mechanism, the 694 forwarding sub-layer processing node MAY be a DetNet unaware, i.e., 695 standard, MPLS LSR. Such TE LSPs may provide LSP forwarding service 696 as defined in, but not limited to, [RFC3209], [RFC3270], [RFC3272], 697 [RFC3473], [RFC4875], [RFC5440], and [RFC8306]. 699 More specifically, as mentioned above, the DetNet forwarding sub- 700 layer provides explicit routes and allocated resources, and F-Labels 701 are used to map to each. Explicit routes are supported based on the 702 topmost (outermost) F-Label that is pushed or swapped and the LSP 703 that corresponds to this label. This topmost (outgoing) label MUST 704 be associated with a provisioned outgoing interface and, for non- 705 point-to-point outgoing interfaces, a next hop LSR. Note that this 706 information MUST be provisioned via configuration or the controller 707 plane. In the previously mentioned special case where there are no 708 added F-labels and the outgoing interface is not a point-to-point 709 interface, the outgoing interface MUST also be associated with a next 710 hop LSR. 712 Resources may be allocated in a hierarchical fashion per LSP that is 713 represented by each F-Label. Each LSP MAY be provisioned with a 714 service parameter that dictates the specific traffic treatment to be 715 received by the traffic carried over that LSP. Implementations of 716 this document MUST ensure that traffic carried over each LSP 717 represented by one or more F-Labels receives the traffic treatment 718 provisioned for that LSP. Typical mechanisms used to provide 719 different treatment to different flows includes the allocation of 720 system resources (such as queues and buffers) and provisioning of 721 related parameters (such as shaping, and policing) that may be found 722 in implementations of Resource ReSerVation Protocol (RSVP) [RFC2205] 723 (RSVP) and RSVP-TE [RFC3209] and [RFC3473]. Support can also be 724 provided via an underlying network technology such IEEE802.1 TSN 725 [I-D.ietf-detnet-mpls-over-tsn]. The specific mechanisms selected by 726 a DetNet node to ensure DetNet service delivery requirements are met 727 for supported DetNet flows is outside the scope of this document. 729 Packets that are marked in a way that do not correspond to allocated 730 resources, e.g., lack a provisioned F-Label, can disrupt the QoS 731 offered to properly reserved DetNet flows by using resources 732 allocated to the reserved flows. Therefore, the network nodes of a 733 DetNet network: 735 o MUST defend the DetNet QoS by discarding or remarking (to an 736 allocated DetNet flow or non-competing non-DetNet flow) packets 737 received that are not associated with a completed resource 738 allocation. 740 o MUST NOT use a DetNet allocated resource, e.g. a queue or shaper 741 reserved for DetNet flows, for any packet that does match the 742 corresponding DetNet flow. 744 o MUST ensure a QoS flow does not exceed its allocated resources or 745 provisioned service level, 747 o MUST ensure a CoS flow or service class does not impact the 748 service delivered to other flows. This requirement is similar to 749 the requirement for MPLS LSRs that CoS LSPs do not impact the 750 resources allocated to TE LSPs, e.g., via [RFC3473]. 752 Subsequent sections provide additional considerations related to CoS 753 (Section 4.6.1), QoS (Section 4.6.2) and aggregation (Section 4.4). 755 4.3. OAM Indication 757 OAM follows the procedures set out in [RFC5085] with the restriction 758 that only Virtual Circuit Connectivity Verification (VCCV) type 1 is 759 supported. 761 As shown in Figure 3 of [RFC5085] when the first nibble of the d-CW 762 is 0x0 the payload following the d-CW is normal user data. However, 763 when the first nibble of the d-CW is 0x1, the payload that follows 764 the d-CW is an OAM payload with the OAM type indicated by the value 765 in the d-CW Channel Type field. 767 The reader is referred to [RFC5085] for a more detailed description 768 of the Associated Channel mechanism, and to the DetNet work on OAM 769 for more information DetNet OAM. 771 Additional considerations on DetNet-specific OAM are subjects for 772 further study. 774 4.4. Flow Aggregation 776 The ability to aggregate individual flows, and their associated 777 resource control, into a larger aggregate is an important technique 778 for improving scaling of control in the data, management and control 779 planes. The DetNet data plane allows for the aggregation of DetNet 780 flows, to improved scaling. There are two methods of supporting flow 781 aggregation covered in this section. 783 The resource control and management aspects of aggregation (including 784 the configuration of queuing, shaping, and policing) are the 785 responsibility of the DetNet controller plane and is out of scope of 786 this documents. It is also the responsibility of the controller 787 plane to ensure that consistent aggregation methods are used. 789 4.4.1. Aggregation Via LSP Hierarchy 791 DetNet flows forwarded via MPLS can leverage MPLS-TE's existing 792 support for hierarchical LSPs (H-LSPs), see [RFC4206]. H-LSPs are 793 typically used to aggregate control and resources, they may also be 794 used to provide OAM or protection for the aggregated LSPs. Arbitrary 795 levels of aggregation naturally falls out of the definition for 796 hierarchy and the MPLS label stack [RFC3032]. DetNet nodes which 797 support aggregation (LSP hierarchy) map one or more LSPs (labels) 798 into and from an H-LSP. Both carried LSPs and H-LSPs may or may not 799 use the TC field, i.e., L-LSPs or E-LSPs [RFC3270]. Such nodes will 800 need to ensure that individual LSPs and H-LSPs receive the traffic 801 treatment required to ensure the required DetNet service is 802 preserved. 804 Additional details of the traffic control capabilities needed at a 805 DetNet-aware node may be covered in the new service definitions 806 mentioned above or in separate future documents. Controller plane 807 mechanisms will also need to ensure that the service required on the 808 aggregate flow are provided, which may include the discarding or 809 remarking mentioned in the previous sections. 811 4.4.2. Aggregating DetNet Flows as a new DetNet flow 813 An aggregate can be built by layering DetNet flows, including both 814 their S-Label and, when present, F-Labels as shown below: 816 +---------------------------------+ 817 | | 818 | DetNet Flow | 819 | Payload Packet | 820 | | 821 +---------------------------------+ <--\ 822 | DetNet Control Word | | 823 +=================================+ | 824 | S-Label | | 825 +---------------------------------+ | 826 | [ F-Label(s) ] | +----DetNet data plane 827 +---------------------------------+ | 828 | DetNet Control Word | | 829 +=================================+ | 830 | A-Label | | 831 +---------------------------------+ | 832 | F-Label(s) | <--/ 833 +---------------------------------+ 834 | Data-Link | 835 +---------------------------------+ 836 | Physical | 837 +---------------------------------+ 839 Figure 6: DetNet Aggregation as a new DetNet Flow 841 Both the aggregation label, which is referred to as an A-Label, and 842 the individual flow's S-Label have their MPLS S bit set indicating 843 bottom of stack, and the d-CW allows the PREOF to work. An A-Label 844 is a special case of an S-Label, whose properties are known only at 845 the aggregation and deaggregation end-points. 847 It is a property of the A-Label that what follows is a d-CW followed 848 by an MPLS label stack. A relay node processing the A-Label would 849 not know the underlying payload type, and the A-Label would be 850 processed as a normal S-Label. This would only be known to a node 851 that was a peer of the node imposing the S-Label. However there is 852 no real need for it to know the payload type during aggregation 853 processing. 855 As in the previous section, nodes supporting this type of aggregation 856 will need to ensure that individual and aggregated flows receive the 857 traffic treatment required to ensure the required DetNet service is 858 preserved. Also, it is the controller plane's responsibility to 859 ensure that the service required on the aggregate flow are properly 860 provisioned. 862 4.5. Service Sub-Layer Considerations 864 The edge and relay node internal procedures related to PREOF are 865 implementation specific. The order of a packet elimination or 866 replication is out of scope in this specification. 868 It is important that the DetNet layer is configured such that a 869 DetNet node never receives its own replicated packets. If it were to 870 receive such packets the replication function would make the loop 871 more destructive of bandwidth than a conventional unicast loop. 872 Ultimately the TTL in the S-Label will cause the packet to die during 873 a transient loop, but given the sensitivity of applications to packet 874 latency the impact on the DetNet application would be severe. To 875 avoid the problem of a transient forwarding loop, changes to an LSP 876 supporting DetNet MUST be loop-free. 878 4.5.1. Edge Node Processing 880 A DetNet Edge node operates in the DetNet forwarding sub-layer and 881 service sub-layer. An edge node is responsible for matching incoming 882 packets to the service they require and encapsulating them 883 accordingly. An edge node may perform PRF, PEF, and or POF. Details 884 on encapsulation can be found in Section 4.2; details on PRF can be 885 found in Section 4.2.2.1; details on PEF can be found in 886 Section 4.2.2.2; and details on POF can be found in Section 4.2.2.3. 888 4.5.2. Relay Node Processing 890 A DetNet Relay node operates in the DetNet forwarding sub-layer and 891 service sub-layer. For DetNet using MPLS forwarding related 892 processing is performed on the F-Label. This processing is done 893 within an extended forwarder function. Whether an incoming DetNet 894 flow receives DetNet specific processing depends on how the 895 forwarding is programmed. Some relay nodes may be DetNet service 896 aware for certain DetNet services, while for other DetNet services 897 these nodes may perform as unmodified LSRs that only understand how 898 to switch MPLS-TE LSPs, i.e., as a transit node, see Section 4.4. 899 Again, this is entirely up to how the forwarding has been programmed. 901 During the elimination and replication process the sequence number of 902 an incoming DetNet packet MUST be preserved and carried in the 903 corresponding outgoing DetNet packet. For example, a relay node that 904 performs both PEF and PRF first performs PEF on incoming packets to 905 create a compound flow. It then performs PRF and copies the app-flow 906 data and the d-CW into packets for each outgoing DetNet member flow. 908 The internal design of a relay node is out of scope of this document. 909 However the reader's attention is drawn to the need to make any PREOF 910 state available to the packet processor(s) dealing with packets to 911 which the PREOF functions must be applied, and to maintain that state 912 is such a way that it is available to the packet processor operation 913 on the next packet in the DetNet flow (which may be a duplicate, a 914 late packet, or the next packet in sequence). 916 4.6. Forwarding Sub-Layer Considerations 918 4.6.1. Class of Service 920 Class and quality of service, i.e., CoS and QoS, are terms that are 921 often used interchangeably and confused with each other. In the 922 context of DetNet, CoS is used to refer to mechanisms that provide 923 traffic forwarding treatment based on aggregate group basis and QoS 924 is used to refer to mechanisms that provide traffic forwarding 925 treatment based on a specific DetNet flow basis. Examples of 926 existing network level CoS mechanisms include DiffServ which is 927 enabled by IP header differentiated services code point (DSCP) field 928 [RFC2474] and MPLS label traffic class field [RFC5462], and at Layer- 929 2, by IEEE 802.1p priority code point (PCP). 931 CoS for DetNet flows carried in PWs and MPLS is provided using the 932 existing MPLS Differentiated Services (DiffServ) architecture 933 [RFC3270]. Both E-LSP and L-LSP MPLS DiffServ modes MAY be used to 934 support DetNet flows. The Traffic Class field (formerly the EXP 935 field) of an MPLS label follows the definition of [RFC5462] and 937 [RFC3270]. The Uniform, Pipe, and Short Pipe DiffServ tunneling and 938 TTL processing models are described in [RFC3270] and [RFC3443] and 939 MAY be used for MPLS LSPs supporting DetNet flows. MPLS Explicit 940 Congestion Notification (ECN) MAY also be used as defined in ECN 941 [RFC5129] and updated by [RFC5462]. 943 4.6.2. Quality of Service 945 In addition to explicit routes, and packet replication and 946 elimination, described in Section 4 above, DetNet provides zero 947 congestion loss and bounded latency and jitter. As described in 948 [RFC8655], there are different mechanisms that may be used separately 949 or in combination to deliver a zero congestion loss service. This 950 includes Quality of Service (QoS) mechanisms at the MPLS layer, that 951 may be combined with the mechanisms defined by the underlying network 952 layer such as 802.1TSN. 954 Quality of Service (QoS) mechanisms for flow specific traffic 955 treatment typically includes a guarantee/agreement for the service, 956 and allocation of resources to support the service. Example QoS 957 mechanisms include discrete resource allocation, admission control, 958 flow identification and isolation, and sometimes path control, 959 traffic protection, shaping, policing and remarking. Example 960 protocols that support QoS control include Resource ReSerVation 961 Protocol (RSVP) [RFC2205] (RSVP) and RSVP-TE [RFC3209] and [RFC3473]. 962 The existing MPLS mechanisms defined to support CoS [RFC3270] can 963 also be used to reserve resources for specific traffic classes. 965 A baseline set of QoS capabilities for DetNet flows carried in PWs 966 and MPLS can be provided by MPLS with Traffic Engineering (MPLS-TE) 967 [RFC3209] and [RFC3473]. TE LSPs can also support explicit routes 968 (path pinning). Current service definitions for packet TE LSPs can 969 be found in "Specification of the Controlled Load Quality of 970 Service", [RFC2211], "Specification of Guaranteed Quality of 971 Service", [RFC2212], and "Ethernet Traffic Parameters", [RFC6003]. 972 Additional service definitions are expected in future documents to 973 support the full range of DetNet services. In all cases, the 974 existing label-based marking mechanisms defined for TE-LSPs and even 975 E-LSPs are use to support the identification of flows requiring 976 DetNet QoS. 978 5. Management and Control Information Summary 980 The specific information needed for the processing of each DetNet 981 service depends on the DetNet node type and the functions being 982 provided on the node. This section summarizes based on the DetNet 983 sub-layer and if the DetNet traffic is being sent or received. All 984 DetNet node types are DetNet forwarding sub-layer aware, while all 985 but transit nodes are service sub-layer aware. This is shown in 986 Figure 2. 988 Much like other MPLS labels, there are a number of alternatives 989 available for DetNet S-Label and F-Label advertisement to an upstream 990 peer node. These include distributed signaling protocols such as 991 RSVP-TE, centralized label distribution via a controller that manages 992 both the sender and the receiver using NETCONF/YANG, BGP, PCEP, etc., 993 and hybrid combinations of the two. The details of the controller 994 plane solution required for the label distribution and the management 995 of the label number space are out of scope of this document. There 996 are particular DetNet considerations and requirements that are 997 discussed in [I-D.ietf-detnet-data-plane-framework]. Conformance 998 language is not used in the summary since it applies to future 999 mechanisms such as those that may be provided in signaling and YANG 1000 models, e.g., [I-D.ietf-detnet-yang]. 1002 5.1. Service Sub-Layer Information Summary 1004 The following summarizes the information that is needed on service 1005 sub-layer aware nodes that transmit DetNet MPLS traffic, on a per 1006 service basis: 1008 o App-Flow identification information, e.g., IP information as 1009 defined in [I-D.ietf-detnet-ip-over-mpls]. Note, this information 1010 is not needed on DetNet relay nodes. 1012 o The sequence number length to be used for the service. Valid 1013 values include 0, 16 and 28 bits. 0 bits cannot be used when PEF 1014 or POF is configured for the service. 1016 o If PRF is to be provided for the service. 1018 o The outgoing S-Label for each of the service's outgoing DetNet 1019 (member) flows. 1021 o The forwarding sub-layer information associated with the output of 1022 the service sub-layer. Note that when the PRF function is 1023 provisioned, this information is per DetNet member flow. 1024 Logically the forwarding sub-layer information is a pointer to 1025 further details of transmission of Detnet flows at the forwarding 1026 sub-layer. 1028 The following summarizes the information that is needed on service 1029 sub-layer aware nodes that receive DetNet MPLS traffic, on a per 1030 service basis: 1032 o The forwarding sub-layer information associated with the input of 1033 the service sub-layer. Note that when the PEF function is 1034 provisioned, this information is per DetNet member flow. 1035 Logically the forwarding sub-layer information is a pointer to 1036 further details of the reception of Detnet flows at the forwarding 1037 sub-layer or A-Label. 1039 o The incoming S-Label for the service. 1041 o If PEF or POF is to be provided for the service. 1043 o The sequence number length to be used for the service. Valid 1044 values included 0, 16 and 28 bits. 0 bits cannot be used when PEF 1045 or POF are configured for the service. 1047 o App-Flow identification information, e.g., IP information as 1048 defined in [I-D.ietf-detnet-ip-over-mpls]. Note, this information 1049 is not needed on DetNet relay nodes. 1051 5.1.1. Service Aggregation Information Summary 1053 Nodes performing aggregation using A-Labels, per 1054 Section Section 4.4.2, require the additional information summarized 1055 in this section. 1057 The following summarizes the additional information that is needed on 1058 a node that sends aggregated flows using A-Labels: 1060 o The S-Labels or F-Labels that are to be carried over each 1061 aggregated service. 1063 o The A-Label associated with each aggregated service. 1065 o The other S-Label information summarized above. 1067 On the receiving node, the A-Label provides the forwarding context of 1068 an incoming interface or an F-Label and is used in subsequent service 1069 or forwarding sub-layer receive processing, as appropriated. The 1070 related additional configuration that may be provided is discussed 1071 elsewhere in this section. 1073 5.2. Forwarding Sub-Layer Information Summary 1075 The following summarizes the information that is needed on forwarding 1076 sub-layer aware nodes that send DetNet MPLS traffic, on a per 1077 forwarding sub-layer flow basis: 1079 o The outgoing F-Label stack to be pushed. The stack may include 1080 H-LSP labels. 1082 o The traffic parameters associated with a specific label in the 1083 stack. Note that there may be multiple sets of traffic parameters 1084 associated with specific labels in the stack, e.g., when H-LSPs 1085 are used. 1087 o Outgoing interface and, for unicast traffic, the next hop 1088 information. 1090 o Sub-network specific parameters on a technology specific basis. 1091 For example, see [I-D.ietf-detnet-mpls-over-tsn]. 1093 The following summarizes the information that is needed on forwarding 1094 sub-layer aware nodes that receive DetNet MPLS traffic, on a per 1095 forwarding sub-layer flow basis: 1097 o The incoming interface. For some implementations and deployment 1098 scenarios, this information may not be needed. 1100 o The incoming F-Label stack to be popped. The stack may include 1101 H-LSP labels. 1103 o How the incoming forwarding sub-layer flow is to be handled, i.e., 1104 forwarded as a transit node, or provided to the service sub-layer. 1106 It is the responsibility of the DetNet controller plane to properly 1107 provision both flow identification information and the flow-specific 1108 resources needed to provided the traffic treatment needed to meet 1109 each flow's service requirements. This applies for aggregated and 1110 individual flows. 1112 6. Security Considerations 1114 Detailed security considerations for DetNet are cataloged in 1115 [I-D.ietf-detnet-security], and more general security considerations 1116 are described in [RFC8655]. This section considers exclusively 1117 security considerations which are specific to the DetNet MPLS data 1118 plane. The considerations raised related to MPLS networks in general 1119 in [RFC5920] are equally applicable to the the DetNet MPLS data 1120 plane. 1122 Security aspects which are unique to DetNet are those whose aim is to 1123 protect the support of specific quality of service aspects of DetNet, 1124 which are primarily to deliver data flows with extremely low packet 1125 loss rates and bounded end-to-end delivery latency. Achieving such 1126 loss rates and bounded latency may not be possible in the face of a 1127 highly capable adversary, such as the one envisioned by the Internet 1128 Threat Model of BCP 72 that can arbitrarily drop or delay any or all 1129 traffic. In order to present meaningful security considerations, we 1130 consider a somewhat weaker attacker who does not control the physical 1131 links of the DetNet domain, but may have the ability to control a 1132 network node within the boundary of the DetNet domain. 1134 An additional consideration for the DetNet data plane is to maintain 1135 integrity of data and delivery of the associated DetNet service 1136 traversing the DetNet network. Application flows can be protected 1137 through whatever means are provided by the underlying technology. 1138 For example, encryption may be used, such as that provided by IPsec 1139 [RFC4301] for IP flows and/or by an underlying sub-net using MACSec 1140 [IEEE802.1AE-2018] for IP over Ethernet (Layer-2) flows. MPLS 1141 doesn't provide any native security services to account for 1142 confidentiality and integrity. 1144 From a data plane perspective this document does not add or modify 1145 any application header information. 1147 At the management and control level DetNet flows are identified on a 1148 per-flow basis, which may provide controller plane attackers with 1149 additional information about the data flows (when compared to 1150 controller planes that do not include per-flow identification). This 1151 is an inherent property of DetNet which has security implications 1152 that should be considered when determining if DetNet is a suitable 1153 technology for any given use case. 1155 To provide uninterrupted availability of the DetNet service, 1156 provisions can be made against DOS attacks and delay attacks. To 1157 protect against DOS attacks, excess traffic due to malicious or 1158 malfunctioning devices is prevented or mitigated through the use of 1159 existing mechanisms, for example by policing and shaping incoming 1160 traffic. To prevent DetNet packets from being delayed by an entity 1161 external to a DetNet domain, DetNet technology definition can allow 1162 for the mitigation of on-path attackers, for example through use of 1163 authentication and authorization of devices within the DetNet domain. 1165 7. IANA Considerations 1167 This document makes no IANA requests. 1169 8. Acknowledgements 1171 The authors wish to thank Pat Thaler, Norman Finn, Loa Anderson, 1172 David Black, Rodney Cummings, Ethan Grossman, Tal Mizrahi, David 1173 Mozes, Craig Gunther, George Swallow, Yuanlong Jiang, Jeong-dong Ryoo 1174 and Carlos J. Bernardos for their various contributions to this 1175 work. 1177 9. Contributors 1179 RFC7322 limits the number of authors listed on the front page of a 1180 draft to a maximum of 5. The editor wishes to thank and acknowledge 1181 the following author for contributing text to this draft. 1183 Don Fedyk 1184 LabN Consulting, L.L.C. 1185 Email: dfedyk@labn.net 1187 10. References 1189 10.1. Normative References 1191 [I-D.ietf-detnet-data-plane-framework] 1192 Varga, B., Farkas, J., Berger, L., Malis, A., and S. 1193 Bryant, "DetNet Data Plane Framework", draft-ietf-detnet- 1194 data-plane-framework-06 (work in progress), May 2020. 1196 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1197 Requirement Levels", BCP 14, RFC 2119, 1198 DOI 10.17487/RFC2119, March 1997, 1199 . 1201 [RFC2211] Wroclawski, J., "Specification of the Controlled-Load 1202 Network Element Service", RFC 2211, DOI 10.17487/RFC2211, 1203 September 1997, . 1205 [RFC2212] Shenker, S., Partridge, C., and R. Guerin, "Specification 1206 of Guaranteed Quality of Service", RFC 2212, 1207 DOI 10.17487/RFC2212, September 1997, 1208 . 1210 [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol 1211 Label Switching Architecture", RFC 3031, 1212 DOI 10.17487/RFC3031, January 2001, 1213 . 1215 [RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y., 1216 Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack 1217 Encoding", RFC 3032, DOI 10.17487/RFC3032, January 2001, 1218 . 1220 [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., 1221 and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP 1222 Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001, 1223 . 1225 [RFC3270] Le Faucheur, F., Wu, L., Davie, B., Davari, S., Vaananen, 1226 P., Krishnan, R., Cheval, P., and J. Heinanen, "Multi- 1227 Protocol Label Switching (MPLS) Support of Differentiated 1228 Services", RFC 3270, DOI 10.17487/RFC3270, May 2002, 1229 . 1231 [RFC3443] Agarwal, P. and B. Akyol, "Time To Live (TTL) Processing 1232 in Multi-Protocol Label Switching (MPLS) Networks", 1233 RFC 3443, DOI 10.17487/RFC3443, January 2003, 1234 . 1236 [RFC3473] Berger, L., Ed., "Generalized Multi-Protocol Label 1237 Switching (GMPLS) Signaling Resource ReserVation Protocol- 1238 Traffic Engineering (RSVP-TE) Extensions", RFC 3473, 1239 DOI 10.17487/RFC3473, January 2003, 1240 . 1242 [RFC4206] Kompella, K. and Y. Rekhter, "Label Switched Paths (LSP) 1243 Hierarchy with Generalized Multi-Protocol Label Switching 1244 (GMPLS) Traffic Engineering (TE)", RFC 4206, 1245 DOI 10.17487/RFC4206, October 2005, 1246 . 1248 [RFC4385] Bryant, S., Swallow, G., Martini, L., and D. McPherson, 1249 "Pseudowire Emulation Edge-to-Edge (PWE3) Control Word for 1250 Use over an MPLS PSN", RFC 4385, DOI 10.17487/RFC4385, 1251 February 2006, . 1253 [RFC5085] Nadeau, T., Ed. and C. Pignataro, Ed., "Pseudowire Virtual 1254 Circuit Connectivity Verification (VCCV): A Control 1255 Channel for Pseudowires", RFC 5085, DOI 10.17487/RFC5085, 1256 December 2007, . 1258 [RFC5129] Davie, B., Briscoe, B., and J. Tay, "Explicit Congestion 1259 Marking in MPLS", RFC 5129, DOI 10.17487/RFC5129, January 1260 2008, . 1262 [RFC5462] Andersson, L. and R. Asati, "Multiprotocol Label Switching 1263 (MPLS) Label Stack Entry: "EXP" Field Renamed to "Traffic 1264 Class" Field", RFC 5462, DOI 10.17487/RFC5462, February 1265 2009, . 1267 [RFC5586] Bocci, M., Ed., Vigoureux, M., Ed., and S. Bryant, Ed., 1268 "MPLS Generic Associated Channel", RFC 5586, 1269 DOI 10.17487/RFC5586, June 2009, 1270 . 1272 [RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and 1273 L. Yong, "The Use of Entropy Labels in MPLS Forwarding", 1274 RFC 6790, DOI 10.17487/RFC6790, November 2012, 1275 . 1277 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1278 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1279 May 2017, . 1281 [RFC8655] Finn, N., Thubert, P., Varga, B., and J. Farkas, 1282 "Deterministic Networking Architecture", RFC 8655, 1283 DOI 10.17487/RFC8655, October 2019, 1284 . 1286 10.2. Informative References 1288 [I-D.ietf-detnet-ip] 1289 Varga, B., Farkas, J., Berger, L., Fedyk, D., and S. 1290 Bryant, "DetNet Data Plane: IP", draft-ietf-detnet-ip-07 1291 (work in progress), July 2020. 1293 [I-D.ietf-detnet-ip-over-mpls] 1294 Varga, B., Berger, L., Fedyk, D., Bryant, S., and J. 1295 Korhonen, "DetNet Data Plane: IP over MPLS", draft-ietf- 1296 detnet-ip-over-mpls-07 (work in progress), September 2020. 1298 [I-D.ietf-detnet-mpls-over-tsn] 1299 Varga, B., Farkas, J., Malis, A., and S. Bryant, "DetNet 1300 Data Plane: MPLS over IEEE 802.1 Time Sensitive Networking 1301 (TSN)", draft-ietf-detnet-mpls-over-tsn-03 (work in 1302 progress), June 2020. 1304 [I-D.ietf-detnet-security] 1305 Mizrahi, T. and E. Grossman, "Deterministic Networking 1306 (DetNet) Security Considerations", draft-ietf-detnet- 1307 security-11 (work in progress), August 2020. 1309 [I-D.ietf-detnet-yang] 1310 Geng, X., Chen, M., Ryoo, Y., Fedyk, D., Li, Z., and R. 1311 Rahman, "Deterministic Networking (DetNet) Configuration 1312 YANG Model", draft-ietf-detnet-yang-07 (work in progress), 1313 July 2020. 1315 [IEEE802.1AE-2018] 1316 IEEE Standards Association, "IEEE Std 802.1AE-2018 MAC 1317 Security (MACsec)", 2018, 1318 . 1320 [RFC2205] Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and S. 1321 Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1 1322 Functional Specification", RFC 2205, DOI 10.17487/RFC2205, 1323 September 1997, . 1325 [RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black, 1326 "Definition of the Differentiated Services Field (DS 1327 Field) in the IPv4 and IPv6 Headers", RFC 2474, 1328 DOI 10.17487/RFC2474, December 1998, 1329 . 1331 [RFC3272] Awduche, D., Chiu, A., Elwalid, A., Widjaja, I., and X. 1332 Xiao, "Overview and Principles of Internet Traffic 1333 Engineering", RFC 3272, DOI 10.17487/RFC3272, May 2002, 1334 . 1336 [RFC3985] Bryant, S., Ed. and P. Pate, Ed., "Pseudo Wire Emulation 1337 Edge-to-Edge (PWE3) Architecture", RFC 3985, 1338 DOI 10.17487/RFC3985, March 2005, 1339 . 1341 [RFC4301] Kent, S. and K. Seo, "Security Architecture for the 1342 Internet Protocol", RFC 4301, DOI 10.17487/RFC4301, 1343 December 2005, . 1345 [RFC4448] Martini, L., Ed., Rosen, E., El-Aawar, N., and G. Heron, 1346 "Encapsulation Methods for Transport of Ethernet over MPLS 1347 Networks", RFC 4448, DOI 10.17487/RFC4448, April 2006, 1348 . 1350 [RFC4875] Aggarwal, R., Ed., Papadimitriou, D., Ed., and S. 1351 Yasukawa, Ed., "Extensions to Resource Reservation 1352 Protocol - Traffic Engineering (RSVP-TE) for Point-to- 1353 Multipoint TE Label Switched Paths (LSPs)", RFC 4875, 1354 DOI 10.17487/RFC4875, May 2007, 1355 . 1357 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 1358 Element (PCE) Communication Protocol (PCEP)", RFC 5440, 1359 DOI 10.17487/RFC5440, March 2009, 1360 . 1362 [RFC5920] Fang, L., Ed., "Security Framework for MPLS and GMPLS 1363 Networks", RFC 5920, DOI 10.17487/RFC5920, July 2010, 1364 . 1366 [RFC5921] Bocci, M., Ed., Bryant, S., Ed., Frost, D., Ed., Levrau, 1367 L., and L. Berger, "A Framework for MPLS in Transport 1368 Networks", RFC 5921, DOI 10.17487/RFC5921, July 2010, 1369 . 1371 [RFC6003] Papadimitriou, D., "Ethernet Traffic Parameters", 1372 RFC 6003, DOI 10.17487/RFC6003, October 2010, 1373 . 1375 [RFC6073] Martini, L., Metz, C., Nadeau, T., Bocci, M., and M. 1376 Aissaoui, "Segmented Pseudowire", RFC 6073, 1377 DOI 10.17487/RFC6073, January 2011, 1378 . 1380 [RFC8306] Zhao, Q., Dhody, D., Ed., Palleti, R., and D. King, 1381 "Extensions to the Path Computation Element Communication 1382 Protocol (PCEP) for Point-to-Multipoint Traffic 1383 Engineering Label Switched Paths", RFC 8306, 1384 DOI 10.17487/RFC8306, November 2017, 1385 . 1387 [RFC8660] Bashandy, A., Ed., Filsfils, C., Ed., Previdi, S., 1388 Decraene, B., Litkowski, S., and R. Shakir, "Segment 1389 Routing with the MPLS Data Plane", RFC 8660, 1390 DOI 10.17487/RFC8660, December 2019, 1391 . 1393 Authors' Addresses 1395 Balazs Varga (editor) 1396 Ericsson 1397 Magyar Tudosok krt. 11. 1398 Budapest 1117 1399 Hungary 1401 Email: balazs.a.varga@ericsson.com 1402 Janos Farkas 1403 Ericsson 1404 Magyar Tudosok krt. 11. 1405 Budapest 1117 1406 Hungary 1408 Email: janos.farkas@ericsson.com 1410 Lou Berger 1411 LabN Consulting, L.L.C. 1413 Email: lberger@labn.net 1415 Andrew G. Malis 1416 Malis Consulting 1418 Email: agmalis@gmail.com 1420 Stewart Bryant 1421 Futurewei Technologies 1423 Email: stewart.bryant@gmail.com 1425 Jouni Korhonen 1427 Email: jouni.nospam@gmail.com