idnits 2.17.00 (12 Aug 2021) /tmp/idnits39358/draft-andersson-mpls-mna-fwk-01.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The document seems to lack the recommended RFC 2119 boilerplate, even if it appears to use RFC 2119 keywords -- however, there's a paragraph with a matching beginning. Boilerplate error? (The document does seem to have the reference to RFC 2119 which the ID-Checklist requires). -- The document date (27 April 2022) is 17 days in the past. Is this intentional? Checking references for intended status: Informational ---------------------------------------------------------------------------- No issues found here. Summary: 0 errors (**), 0 flaws (~~), 1 warning (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 MPLS Working Group L. Andersson 3 Internet-Draft Bronze Dragon Consulting 4 Intended status: Informational S. Bryant 5 Expires: 29 October 2022 University of Surrey 5GIC 6 M. Bocci 7 Nokia 8 T. Li 9 Juniper Networks 10 27 April 2022 12 MPLS Network Actions Framework 13 draft-andersson-mpls-mna-fwk-01 15 Abstract 17 This document specifies an architectural framework for the MPLS 18 Network Actions (MNA) technologies. MNA technologies are used to 19 indicate actions for Label Switched Paths (LSPs) and/or packets and 20 to transfer data needed for these actions. 22 The document describes a common set of protocol actions and 23 information elements supporting additional operational models and 24 capabilities of MPLS networks. Some of these actions are defined in 25 existing MPLS specifications, while others require extensions to 26 existing specifications to meet the requirements found in 27 "Requirements for MPLS Label Stack Indicators and Ancillary Data". 29 This document is the result of work started in MPLS Open Desgign 30 Team, with participation by the MPLS, PALS and DETNET working groups. 32 Status of This Memo 34 This Internet-Draft is submitted in full conformance with the 35 provisions of BCP 78 and BCP 79. 37 Internet-Drafts are working documents of the Internet Engineering 38 Task Force (IETF). Note that other groups may also distribute 39 working documents as Internet-Drafts. The list of current Internet- 40 Drafts is at https://datatracker.ietf.org/drafts/current/. 42 Internet-Drafts are draft documents valid for a maximum of six months 43 and may be updated, replaced, or obsoleted by other documents at any 44 time. It is inappropriate to use Internet-Drafts as reference 45 material or to cite them other than as "work in progress." 47 This Internet-Draft will expire on 29 October 2022. 49 Copyright Notice 51 Copyright (c) 2022 IETF Trust and the persons identified as the 52 document authors. All rights reserved. 54 This document is subject to BCP 78 and the IETF Trust's Legal 55 Provisions Relating to IETF Documents (https://trustee.ietf.org/ 56 license-info) in effect on the date of publication of this document. 57 Please review these documents carefully, as they describe your rights 58 and restrictions with respect to this document. Code Components 59 extracted from this document must include Revised BSD License text as 60 described in Section 4.e of the Trust Legal Provisions and are 61 provided without warranty as described in the Revised BSD License. 63 Table of Contents 65 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 66 1.1. Requirement Language . . . . . . . . . . . . . . . . . . 4 67 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 68 1.2.1. Normative Definitions . . . . . . . . . . . . . . . . 4 69 1.2.2. Abbreviations . . . . . . . . . . . . . . . . . . . . 5 70 2. Structure . . . . . . . . . . . . . . . . . . . . . . . . . . 6 71 2.1. Scopes . . . . . . . . . . . . . . . . . . . . . . . . . 7 72 2.2. Partial Processing . . . . . . . . . . . . . . . . . . . 7 73 2.3. Signaling . . . . . . . . . . . . . . . . . . . . . . . . 8 74 2.4. Positioning . . . . . . . . . . . . . . . . . . . . . . . 8 75 2.5. State . . . . . . . . . . . . . . . . . . . . . . . . . . 8 76 3. Encoding . . . . . . . . . . . . . . . . . . . . . . . . . . 8 77 3.1. The MNA Label . . . . . . . . . . . . . . . . . . . . . . 9 78 3.1.1. Existing Base SPL . . . . . . . . . . . . . . . . . . 9 79 3.1.2. New Base SPL . . . . . . . . . . . . . . . . . . . . 9 80 3.1.3. New Extended SPL . . . . . . . . . . . . . . . . . . 9 81 3.1.4. User-Defined Label . . . . . . . . . . . . . . . . . 9 82 3.2. TC and TTL . . . . . . . . . . . . . . . . . . . . . . . 9 83 3.2.1. TC and TTL retained . . . . . . . . . . . . . . . . . 9 84 3.2.2. TC and TTL Repurposed . . . . . . . . . . . . . . . . 10 85 3.3. Length of the NAS . . . . . . . . . . . . . . . . . . . . 10 86 3.3.1. Last/Continuation Bits . . . . . . . . . . . . . . . 10 87 3.3.2. Length Field . . . . . . . . . . . . . . . . . . . . 11 88 3.4. Encoding of Scopes . . . . . . . . . . . . . . . . . . . 11 89 3.5. Encoding a Network Action . . . . . . . . . . . . . . . . 11 90 3.5.1. Bit Catalogs . . . . . . . . . . . . . . . . . . . . 11 91 3.5.2. Operation Codes . . . . . . . . . . . . . . . . . . . 12 92 3.6. Encoding of Post-Stack Data . . . . . . . . . . . . . . . 12 93 3.6.1. First Nibble Considerations . . . . . . . . . . . . . 12 94 4. Definition of a Network Action . . . . . . . . . . . . . . . 13 95 5. Management Considerations . . . . . . . . . . . . . . . . . . 14 96 6. Security Considerations . . . . . . . . . . . . . . . . . . . 14 97 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 98 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14 99 9. Editorial attic . . . . . . . . . . . . . . . . . . . . . . . 14 100 9.1. Process Note on E2E . . . . . . . . . . . . . . . . . . . 15 101 9.2. Concepts used in this Framework . . . . . . . . . . . . . 15 102 9.3. LSE . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 103 9.4. MPLS Forwarding model . . . . . . . . . . . . . . . . . . 16 104 9.4.1. Orginal Model . . . . . . . . . . . . . . . . . . . . 16 105 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 17 106 10.1. Normative References . . . . . . . . . . . . . . . . . . 17 107 10.2. Informative References . . . . . . . . . . . . . . . . . 18 108 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18 110 1. Introduction 112 This document specifies an architectural framework for the MPLS 113 Network Actions (MNA) technologies. MNA technologies are used to 114 indicate actions for LSPs and/or packets and to transfer data needed 115 for these actions. 117 The document describes a common set of protocol actions and 118 information elements supporting additional operational models and 119 capabilities of MPLS networks. Some of these actions are defined in 120 existing MPLS specifications, while others require extensions to 121 existing specifications to meet the requirements found in 122 [I-D.bocci-mpls-miad-adi-requirements]. [Ed.: In a future draft, the 123 language in the requirements draft will be changed to align with the 124 terminology found here.] 126 Forwarding actions are instructions to MPLS routers to apply 127 additional actions when forwarding a packet. These might include 128 load-balancing a packet given its entropy, whether or not to perform 129 fast reroute on a failure, and whether or not a packet has metadata 130 relevant to the forwarding decisions along the path. 132 This document generalizes the concept of "forwarding actions" into 133 "network actions" to include any action that an MPLS router is 134 requested to take on the packet. That includes any forwarding 135 action, but may include other operations (such as security functions, 136 OAM procedures, etc.) that are not directly related to forwarding of 137 the packet. 139 This document is the result of work started in MPLS Open Desgign 140 Team, with participation by the MPLS, PALS and DETNET working groups. 142 1.1. Requirement Language 144 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 145 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 146 "OPTIONAL" in this document are to be interpreted as described in 147 BCP14 [RFC2119] [RFC8174] when, and only when, they appear in all 148 capitals, as shown here. 150 1.2. Terminology 152 1.2.1. Normative Definitions 154 * Ancillary Data (AD): Data relating to the MPLS packet that may be 155 used to affect the forwarding or other processing of that packet, 156 either at an Label Edge Router (LER) [RFC4221] or Label Switching 157 Router (LSR). This data may be encoded within a network action 158 sub-stack (see below) (in-stack data), and/or after the bottom of 159 the label stack (post-stack data). 161 * Network Action: An operation to be performed on a packet. A 162 network action may affect router state, packet forwarding, or it 163 may affect the packet in some other way. A network action is said 164 to be present if there is an indicator in the packet that invokes 165 the action. 167 * Network Action Indication (NAI): An indication in the packet that 168 a certain network action is to be perfomed. There may be 169 associated ancillary data in the packet. 171 * Network Action Sub-Stack (NAS): A set of related, contiguous Label 172 Stack Entries (LSEs). The first LSE is the Network Action Sub- 173 stack Indicator. The TC and TTL values in the sub-stack may be 174 redefined. The label field in the second and following LSE may be 175 redefined. Solutions MUST NOT redefine the S bit. See 176 Section 3.1 through Section 3.5. 178 * Network Action Sub-Stack Indicator (NSI): An LSE that contains a 179 special label that indicates the start of a Network Action Sub- 180 stack. 182 * Scope: The set of nodes that should perform a given action. 184 1.2.2. Abbreviations 186 +==============+===========+========================================+ 187 | Abbreviation |Meaning | Reference | 188 +==============+===========+========================================+ 189 | AD |Ancillary | [I-D.bocci-mpls-miad-adi-requirements] | 190 | |Data | | 191 +--------------+-----------+----------------------------------------+ 192 | bSPL |Base | [RFC9017] | 193 | |Special | | 194 | |Purpose | | 195 | |Label | | 196 +--------------+-----------+----------------------------------------+ 197 | ECMP |Equal Cost | | 198 | |Multipath | | 199 +--------------+-----------+----------------------------------------+ 200 | eSPL |Extended | [RFC9017] | 201 | |Special | | 202 | |Purpose | | 203 | |Label | | 204 +--------------+-----------+----------------------------------------+ 205 | HBH |Hop by hop | In the MNA context, this document. | 206 +--------------+-----------+----------------------------------------+ 207 | I2E |Ingress to | In the MNA context, this document. | 208 | |Egress | | 209 +--------------+-----------+----------------------------------------+ 210 | ISD |In stack | [I-D.bocci-mpls-miad-adi-requirements] | 211 | |data | | 212 +--------------+-----------+----------------------------------------+ 213 | LSE |Label Stack| [RFC3032] | 214 | |Entry | | 215 +--------------+-----------+----------------------------------------+ 216 | MNA |MPLS | This documnent | 217 | |Network | | 218 | |Actions | | 219 +--------------+-----------+----------------------------------------+ 220 | NAI |Network | [I-D.bocci-mpls-miad-adi-requirements] | 221 | |Action | | 222 | |Indicator | | 223 +--------------+-----------+----------------------------------------+ 224 | NAS |Network | This document | 225 | |Action Sub-| | 226 | |Stack | | 227 +--------------+-----------+----------------------------------------+ 228 | PSD |Post stack | [I-D.bocci-mpls-miad-adi-requirements] | 229 | |data | and Section 3.6 | 230 +--------------+-----------+----------------------------------------+ 231 | SPL |Special | [RFC9017] | 232 | |Purpose | | 233 | |Label | | 234 +--------------+-----------+----------------------------------------+ 236 Table 1: Abbreviations 238 2. Structure 240 An MNA solution is envisioned as a set of network action sub-stacks 241 that indicate the network actions being invoked, plus possible post- 242 stack data. A solution must specify where in the label stack the 243 network actions sub-stacks occur, if and how frequently they should 244 be replicated, and how network action sub-stack and post-stack data 245 are encoded. 247 A network action sub-stack contains: 249 * Label: A special label is used to indicate the start of a network 250 action sub-stack. 252 * Indicators: A set of indicators that describes the set of network 253 actions. 255 * In-Stack Data: A set of zero or more LSEs that carry ancillary 256 data for the present network actions. 258 Each network action present in the network action sub-stack may have 259 zero or more LSEs of in-stack data. The ordering of the in-stack 260 data LSEs corresponds to the ordering of the network action 261 indicators. The encoding of the in-stack data, if any, for a network 262 action must be specified in the document that defines the network 263 action. 265 Certain network actions may also specify that data is carried after 266 the label stack. This is called post-stack data. The encoding of 267 the post-stack data, if any, for a network action must be specified 268 in the document that defines the network action. If multiple network 269 actions are present and have post-stack data, the ordering of their 270 post-stack data corresponds to the ordering of the network action 271 indicators. 273 A solution must specify the order that network actions are to be 274 applied to the packet. 276 2.1. Scopes 278 A network action may need to be processed by every node along the 279 path, or some subset of the nodes along its path. Some of the scopes 280 that an action may have are: 282 * Hop-by-hop (HBH): Every node along the path will perform the 283 action. 285 * Ingress-to-Egress (I2E): Only the last node on the path will 286 perform the action. 288 * Select: Only specific nodes along the path will perform the 289 action. 291 If a solution supports the select scope, it must describe how it 292 specifies the set of nodes to perform the actions. 294 2.2. Partial Processing 296 Legacy devices that do not recognize the MNA label will discard the 297 packet as described in [RFC3031]. 299 Devices that do recognize the MNA label may not implement all of the 300 present network actions. A solution must specify how unrecognized 301 present network actions should be handled. 303 One alternative is that an implementation should stop processing 304 network actions when it encounters an unrecognized network action. 305 Subsequent present network actions would not be applied. The result 306 is dependent on the solution's order of operations. 308 Another alternative is that an implementation should drop any packet 309 that contains any unrecognized present network actions. 311 A third alternative is that an implementation should perform all 312 recognized present network actions, but ignore all unrecognized 313 present network actions. 315 Other alternatives may also be possible and should be specified by 316 the solution. 318 2.3. Signaling 320 A node that wishes to make use of MNA and apply network actions to a 321 packet must understand the nodes that the packet will transit and 322 whether or not the nodes support MNA and the network actions that are 323 to be invoked. These capabilities are presumed to be signaled by 324 protocols that are out-of-scope for this document and are presumed to 325 have per-network action granularity. If a solution requires 326 alternate signaling, it must specify so explicitly. 328 A node that pushes a NAS onto the label stack is responsible for 329 determining that all nodes that should process the NAS will have the 330 NAS within its Readable Label Depth (RLD). A node should use 331 signaling (e.g., [RFC9088]) to determine this. 333 2.4. Positioning 335 A network action sub-stack should never occur at the top of the MPLS 336 label stack. A node that is responsible for popping a forwarding 337 label immediately above a network action sub-stack must also pop any 338 network action sub-stacks that immediately follow. 340 2.5. State 342 A network action can affect state in the network. This implies that 343 a packet may affect how subsequent packets are handled. 345 3. Encoding 347 Several possibilities to carry NAI's have been discussed in MNA 348 drafts and in the MPLS Open DT. In this section, we enumerate the 349 possibilities and some considerations for the various alternatives. 351 All types of network actions are represented in the MPLS label stack 352 by a set of LSEs termed a network action sub-stack (NAS). An NAS 353 consists of a special label, followed by LSEs that specify which 354 network actions are to be performed on the packet, and the in-stack 355 ancillary data for each indicated network action. 357 [I-D.bocci-mpls-miad-adi-requirements] requires that a solution not 358 add unnecessary LSEs to the sub-stack (Section 3.1, requirement 5). 359 Accordingly, solutions should also make efficient use of the bits 360 within the sub-stack, as inefficient use of the bits will result in 361 the addition of unnecessary LSEs. 363 3.1. The MNA Label 365 The first LSE in a network action sub-stack contains a special label 366 that indicates a network action sub-stack. A solution has several 367 choices for this special label. 369 3.1.1. Existing Base SPL 371 A solution may reuse an existing Base SPL (bSPL). If it elects to do 372 so, it must explain how the usage is backwards compatible, including 373 in the case where there is ISD. 375 3.1.2. New Base SPL 377 A solution may select a new bSPL. 379 3.1.3. New Extended SPL 381 A solution may select a new eSPL. If it elects to do so, it must 382 address the requirement for the minimal number of LSEs. 384 3.1.4. User-Defined Label 386 A solution may allow the network operator to define the label that 387 indicates the network action sub-stack. This creates management 388 overhead for the network operator to coordinate the use of this label 389 across all nodes on the path using management or signaling protocols. 390 If a solution elects to use a user-defined label, the solution should 391 justify this overhead. 393 3.2. TC and TTL 395 In the first LSE of the network action sub-stack, only the 20 bits of 396 Label Value and the Bottom of Stack bit are significant, the TC field 397 (3 bits) and the TTL (8 bits) are not used. This leaves 11 bits that 398 could be used for other purposes. 400 3.2.1. TC and TTL retained 402 If the solution elects to retain the TC and TTL field, then the first 403 LSE of the network action sub-stack would appear as: 405 0 1 2 3 406 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 1 407 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 408 | Label | TC |S| TTL | 409 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 410 Label: Label value, 20 bits 411 TC: Traffic Class, 3 bits 412 S: Bottom of Stack, 1 bit 413 TTL: Time To Live 415 Further LSEs would be needed to encode NAIs. If a solution elects to 416 retain these fields, it must address the requirement for the minimal 417 number of LSEs. 419 3.2.2. TC and TTL Repurposed 421 If the solution elects to reuse the TC and TTL field, then the first 422 LSE of the network action sub-stack would appear as: 424 0 1 2 3 425 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 1 426 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 427 | Label |x x x|S|x x x x x x x x| 428 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 429 Label: Label value, 20 bits 430 x: Bit available for solution definition 431 S: Bottom of Stack, 1 bit 433 The solution may use more LSEs to contain NAIs. 435 3.3. Length of the NAS 437 A solution must have a mechanism to indicate the length of the NAS. 438 This must be easily processed even by implementations that do not 439 understand the full contents of the NAS. Two options are described 440 below, other solutions may be possible. 442 3.3.1. Last/Continuation Bits 444 A solution may use a bit per LSE to indicate whether the NAS 445 continues into the next LSE or not. The bit may indicate 446 continuation by being set or by being clear. The overhead of this 447 approach is one bit per LSE and has the advantage that it can 448 effectively encode an arbitrarily sized NAS. This approach is 449 efficient if the NAS is small. 451 3.3.2. Length Field 453 A solution may opt to have a fixed size length field at a fixed 454 location within the NAS. The fixed size of the length field may not 455 be large enough to support all possible NAS contents. This approach 456 may be more efficient if the NAS is longer, but not longer than can 457 be described by the length field. 459 Advice from hardware designers advocates a length field as this 460 minimizes branching in the logic. 462 3.4. Encoding of Scopes 464 A solution may choose to explicitly encode the scope of the actions 465 contained in a network action sub-stack. A solution may also choose 466 to have the scope encoded implicitly, based on the actions present in 467 the network action sub-stack. This choice may have performance 468 implications as an implementation might have to parse the network 469 actions that are present in a network action sub-stack only to 470 discover that there are no actions for it to perform. 472 Solutions need to consider the order of scoped NAIs and their 473 associated AD within individual sub-stacks and the order of per-scope 474 sub-stacks in order that network actions and the AD can be most 475 readily found and not need to processed by nodes that are not 476 required to handle those actions. 478 3.5. Encoding a Network Action 480 Two options for encoding NAIs are described below, other solutions 481 may be possible. Any solution should allow encoding of an arbitrary 482 number of NAIs. 484 3.5.1. Bit Catalogs 486 A solution may opt to encode the set of network actions as a list of 487 bits, sometimes known as a catalog. The solution must provide a 488 mechanism to determine how many LSEs are devoted to the catalog. A 489 set bit in the catalog would indicate that the corresponding network 490 action is present. 492 Catalogs are efficient if the number of present network actions is 493 relatively high and if the size of the necessary catalog is small. 494 For example, if the first 16 actions are all present, a catalog can 495 encode this in 16 bits. However, if the number of possible actions 496 is large, then a catalog can become inefficient. Selecting only one 497 action that is the 256th action would require a catalog of 256 bits, 498 which would require more than one LSE. 500 3.5.2. Operation Codes 502 A solution may opt to encode the set of present network actions as a 503 list of operation codes (opcodes). Each opcode is a fixed number of 504 bits. The size of the opcode bounds the number of network actions 505 that the solution can support. 507 Opcodes are efficient if there are only one or two active network 508 actions. For example, if an opcode is 8 bits, then two active 509 network actions could be encoded in in 16 bits. However, if there 510 are 16 actions required, then opcodes would consume 128 bits. 511 Opcodes are efficient at encoding a large number of possible actions. 512 If only the 256th action is to be selected, that still requires 8 513 bits. 515 3.6. Encoding of Post-Stack Data 517 If there are multiple instances of post-stack data, they should occur 518 in the same order as their relevant network action sub-stacks and 519 then in the same order as their relevant network functions occur 520 within the network action sub-stacks. 522 3.6.1. First Nibble Considerations 524 The first nibble after the label stack has been used to convey 525 information in certain cases. 527 For example, in [RFC4928] this nibble is investigated to find out if 528 it has the value "4" or "6", if it is not, it is assumed that the 529 packet payload is not IPv4 or IPv6 and Equal Cost Multipath (ECMP) is 530 not performed. 532 It should be noted that this is an inexact method, for example an 533 Ethernet Pseudowire without a control word might have "4" or "6" in 534 the first nibble and thus will be ECMP'ed. 536 Nevertheless, the method is implemented and deployed, it is used 537 today and will be for the foreseeable future. 539 The use of the first nibble for BIER is specified in [RFC8296]. Bier 540 sets the first nibble to 5. The same is true for BIER payload, as 541 for any use of the first nibble, it is not possible from the first 542 nibble itself being set to 5, conclude that the payload is BIER. 543 However, it achieves the design goal of [RFC8296], to exclude that 544 the payload is IPv4, IPv6 or a pseudowire. 546 There are possibly more examples, they will be added if we find that 547 they further highlight the issue with using the first nibble. 549 [Ed. Outstanding comments from Adrian: 551 Shouldn't we include RFC4385 for 0b0000 for the PW control word and 552 0b0001 for the PW ACH? 554 This section is all very well, but it doesn't give any direction to 555 the solution developer for what they should do with the first nibble 556 in the post stack data. 558 Is it also relevant to note that there may be other post-stack 559 information that comes before the payload (such as the PW control 560 word, and that the solution must consider the location of the post- 561 stack data in relaiton to that (e.g., immeidately after the LSE with 562 the S bit set) etc.] 564 4. Definition of a Network Action 566 Network actions should be defined in a document and must contain: 568 * Name: The name of the network action. 570 * Network Action Indicator: The bit position or opcode that 571 indicates that the network action is active. 573 * Scope: The document should specify which nodes should perform the 574 network action. The action may apply to each transit node (HBH), 575 only the egress node that pops the final label off of the label 576 stack, or specific nodes along the label switched path. 578 * State: The document should specify if the network action can 579 modify state in the network, and if so, the state that may be 580 modified and its side-effects. 582 * Required/Optional: The document should specify whether a node is 583 required to perform the network action. 585 * In-Stack Data: The number of LSEs of in-stack data. If this is of 586 a variable length, then the solution must specify how an 587 implementation can determine this length without implementing the 588 network action. 590 * Post-Stack Data: The encoding of post-stack data, if any. If this 591 is of a variable length, then the solution must specify how an 592 implementation can determine this length without implementing the 593 network action. 595 A solution should create an IANA registry for network actions. 597 5. Management Considerations 599 Network operators will need to be cognizant of which network actions 600 are supported by which nodes and will need to ensure that this is 601 signalled appropriately. Some solutions may require network-wide 602 configuration to synchronize the use of the labels that indicate the 603 start of an NAS. Solution documents must make clear what management 604 considerations apply to the solutions they are describing. Solutions 605 documents must describe mechanisms for performing network diagnostics 606 in the presence of MNAs. 608 6. Security Considerations 610 The forwarding plane is insecure. If an adversary can affect the 611 forwarding plane, then they can inject data, remove data, corrupt 612 data, or modify data. MNA additionally allows an adversary to make 613 packets perform arbitrary network actions. 615 Link-level security mechanisms can help mitigate some on-link 616 attacks, but does nothing to preclude hostile nodes. 618 End-to-end encryption of an LSP can help provide security, but would 619 make it impossible to process post-stack data. 621 7. IANA Considerations 623 This document does not make any allocations of code points from IANA 624 registries. 626 As long as the "does not make any allocations ..." from IANA is true, 627 this pragraph shoukd be removed by the RFC-Editor. If it turns out 628 that we will need to do IANA allocation, a proper IANA section will 629 be added. 631 8. Acknowledgements 633 The authors would like to thank Adrian Farrel for his contributions 634 and to John Drake for his comments. 636 9. Editorial attic 638 This section contains old material that will be discarded before 639 publication, assuming we don't find it useful between now and then. 641 9.1. Process Note on E2E 643 There has been some discussion on the of the E2E abbreviation. 1. In 644 a mail to the MPLS Working group mailing list Joel Halpern pointed 645 out that the abbreviation E2E has been used in several different 646 meanings. Joel suggested to use another abbreviation. 648 1. Some variants has been proposed, for example. 650 * Ingress to Egress (I2E); alernative abbreviation (i2e) 652 * Egress 654 * LSP Ingress to LSP Egress (LI2LE) 656 * Egress (because the Ingress has already done its thing) 658 * Ultimate Hop 660 * Destination 662 * Start-to-End 664 * Last-LSR 666 * Head to Tail 668 In a few days (counting from the publication date of this document) 669 the working group chairs will take an initiative to poll the working 670 groups for consensus on this. 672 9.2. Concepts used in this Framework 674 +=============+====================+===========+======+ 675 | Concept | Meaning | Reference | Note | 676 +=============+====================+===========+======+ 677 | E2E concept | E2E in MNA context | this | - | 678 | | is defined in... | document | | 679 +-------------+--------------------+-----------+------+ 680 | concept | free text | this | - | 681 | | | document | | 682 +-------------+--------------------+-----------+------+ 684 Table 2: Concepts 686 Not complete, help appreciated. [Ed. This section is planned for 687 removal as it seems unhelpful so far.] 689 9.3. LSE 691 An individual LSE has the following format [RFC3032]: 693 0 1 2 3 694 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 1 695 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 696 | Label | TC |S| TTL | 697 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 699 Label: Label Value, 20 bits 700 TC: Traffic Class, 3 bits 701 S: Bottom of Stack, 1 bit 702 TTL: Time to Live, 8 bits 704 Figure 1: A Label Stack Entry (LSE) 706 9.4. MPLS Forwarding model 708 This is section here to basically to have a place holder where to 709 discuss the development of the MPLS forwrding model. It might be 710 removed. [Ed. So far, it adds no value. Wave bye-bye.] 712 9.4.1. Orginal Model 714 +-----------------------------------------------------------------+ 715 | | 716 | +---------------------+ | 717 | | +------------+ | | 718 | | | MPLS Label | LSE | | 719 | | +---|--------+ | | 720 | +-----|---------------+ | 721 | | | 722 | | +----------------------+ | 723 | | | FIB | | 724 | | | | | 725 | | | +------------+ | +----------------------+ | 726 | +------->|FIB Entry |-----+-->|Forwarding Code | | 727 | | +------------+ | | +----------------------+ | 728 | +----------------------| | | 729 | | | +----------------------+ | 730 | +-->|Forwarding Parameters | | 731 | +----------------------+ | 732 | | 733 | | 734 | LSE = Label Stack Entry (what many people call a label) | 735 | FIB = Forwarding Information (date)Base | 736 +-----------------------------------------------------------------+ 737 Figure 2: MPLS Original Forwarding Model 739 10. References 741 10.1. Normative References 743 [I-D.bocci-mpls-miad-adi-requirements] 744 Bocci, M. and S. Bryant, "Requirements for MPLS Network 745 Action Indicators and MPLS Ancillary Data", Work in 746 Progress, Internet-Draft, draft-bocci-mpls-miad-adi- 747 requirements-04, 11 April 2022, 748 . 751 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 752 Requirement Levels", BCP 14, RFC 2119, 753 DOI 10.17487/RFC2119, March 1997, 754 . 756 [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol 757 Label Switching Architecture", RFC 3031, 758 DOI 10.17487/RFC3031, January 2001, 759 . 761 [RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y., 762 Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack 763 Encoding", RFC 3032, DOI 10.17487/RFC3032, January 2001, 764 . 766 [RFC4221] Nadeau, T., Srinivasan, C., and A. Farrel, "Multiprotocol 767 Label Switching (MPLS) Management Overview", RFC 4221, 768 DOI 10.17487/RFC4221, November 2005, 769 . 771 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 772 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 773 May 2017, . 775 [RFC9017] Andersson, L., Kompella, K., and A. Farrel, "Special- 776 Purpose Label Terminology", RFC 9017, 777 DOI 10.17487/RFC9017, April 2021, 778 . 780 [RFC9088] Xu, X., Kini, S., Psenak, P., Filsfils, C., Litkowski, S., 781 and M. Bocci, "Signaling Entropy Label Capability and 782 Entropy Readable Label Depth Using IS-IS", RFC 9088, 783 DOI 10.17487/RFC9088, August 2021, 784 . 786 10.2. Informative References 788 [RFC4928] Swallow, G., Bryant, S., and L. Andersson, "Avoiding Equal 789 Cost Multipath Treatment in MPLS Networks", BCP 128, 790 RFC 4928, DOI 10.17487/RFC4928, June 2007, 791 . 793 [RFC8296] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., 794 Tantsura, J., Aldrin, S., and I. Meilik, "Encapsulation 795 for Bit Index Explicit Replication (BIER) in MPLS and Non- 796 MPLS Networks", RFC 8296, DOI 10.17487/RFC8296, January 797 2018, . 799 Authors' Addresses 801 Loa Andersson 802 Bronze Dragon Consulting 803 Email: loa@pi.nu 805 Stewart Bryant 806 University of Surrey 5GIC 807 Email: sb@stewartbryant.com 809 Matthew Bocci 810 Nokia 811 Email: matthew.bocci@nokia.com 813 Tony Li 814 Juniper Networks 815 Email: tony.li@tony.li