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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 4379 (Obsoleted by RFC 8029) == Outdated reference: A later version (-04) exists of draft-ravisingh-mpls-el-for-seamless-mpls-00 -- Obsolete informational reference (is this intentional?): RFC 6424 (Obsoleted by RFC 8029) Summary: 2 errors (**), 0 flaws (~~), 2 warnings (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Internet Engineering Task Force N. Akiya 3 Internet-Draft G. Swallow 4 Updates: 4379,6790 (if approved) C. Pignataro 5 Intended status: Standards Track Cisco Systems 6 Expires: April 24, 2014 October 21, 2013 8 Label Switched Path (LSP) Ping/Trace over MPLS Network 9 using Entropy Labels (EL) 10 draft-akiya-mpls-entropy-lsp-ping-00 12 Abstract 14 The Multiprotocol Label Switching (MPLS) Label Switched Path (LSP) 15 Ping and Traceroute are used to exercise specific paths of Equal Cost 16 Multipath (ECMP). This ability has been lost on some scenarios which 17 makes use of [RFC6790]: Entropy Labels (EL). 19 This document extends the MPLS LSP Ping and Traceroute mechanisms to 20 restore the ability of exercising specific paths of ECMP over LSP 21 which make use of Entropy Label. This document updates [RFC4379] and 22 [RFC6790]. 24 Requirements Language 26 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 27 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 28 document are to be interpreted as described in RFC 2119 [RFC2119]. 30 Status of This Memo 32 This Internet-Draft is submitted in full conformance with the 33 provisions of BCP 78 and BCP 79. 35 Internet-Drafts are working documents of the Internet Engineering 36 Task Force (IETF). Note that other groups may also distribute 37 working documents as Internet-Drafts. The list of current Internet- 38 Drafts is at http://datatracker.ietf.org/drafts/current/. 40 Internet-Drafts are draft documents valid for a maximum of six months 41 and may be updated, replaced, or obsoleted by other documents at any 42 time. It is inappropriate to use Internet-Drafts as reference 43 material or to cite them other than as "work in progress." 45 This Internet-Draft will expire on April 24, 2014. 47 Copyright Notice 48 Copyright (c) 2013 IETF Trust and the persons identified as the 49 document authors. All rights reserved. 51 This document is subject to BCP 78 and the IETF Trust's Legal 52 Provisions Relating to IETF Documents 53 (http://trustee.ietf.org/license-info) in effect on the date of 54 publication of this document. Please review these documents 55 carefully, as they describe your rights and restrictions with respect 56 to this document. Code Components extracted from this document must 57 include Simplified BSD License text as described in Section 4.e of 58 the Trust Legal Provisions and are provided without warranty as 59 described in the Simplified BSD License. 61 Table of Contents 63 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 64 2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 3 65 3. Multipath Type 9 . . . . . . . . . . . . . . . . . . . . . . 5 66 4. Initiating LSR Procedures . . . . . . . . . . . . . . . . . . 6 67 5. Responder LSR Procedures . . . . . . . . . . . . . . . . . . 7 68 5.1. IP Based Load Balancer & Not Imposing ELI/EL . . . . . . 7 69 5.2. IP Based Load Balancer & Imposing ELI/EL . . . . . . . . 8 70 5.3. Label Based Load Balancer & Not Imposing ELI/EL . . . . . 8 71 5.4. Label Based Load Balancer & Imposing ELI/EL . . . . . . . 9 72 5.5. FAT MS-PW Stitching LSR . . . . . . . . . . . . . . . . . 9 73 6. Entropy Label FEC . . . . . . . . . . . . . . . . . . . . . . 10 74 7. DS Flags: L and E . . . . . . . . . . . . . . . . . . . . . . 10 75 8. New Multipath Information Type: 10 . . . . . . . . . . . . . 11 76 9. Unsupported Cases . . . . . . . . . . . . . . . . . . . . . . 13 77 10. Security Considerations . . . . . . . . . . . . . . . . . . . 13 78 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 79 11.1. DS Flags . . . . . . . . . . . . . . . . . . . . . . . . 13 80 11.2. Multipath Information Types . . . . . . . . . . . . . . 13 81 11.3. Entropy Label FEC . . . . . . . . . . . . . . . . . . . 13 82 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14 83 13. Contributing Authors . . . . . . . . . . . . . . . . . . . . 14 84 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 85 14.1. Normative References . . . . . . . . . . . . . . . . . . 14 86 14.2. Informative References . . . . . . . . . . . . . . . . . 14 87 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14 89 1. Introduction 90 Section 3.3.1 of [RFC4379] specifies multipath information encoding 91 which can be used by LSP Ping initiator to trace and validate all 92 ECMP paths between ingress and egress. These encodings are 93 sufficient when all the LSRs along the path(s), between ingress and 94 egress, consider same set of "keys" as input for load balancing 95 algorithm: all IP based or all label based. 97 With introduction of [RFC6790], it is quite normal to see set of LSRs 98 performing load balancing based on EL/ELI while others still follow 99 the traditional way (IP based). This results in LSP Ping initiator 100 not be able to trace and validate all ECMP paths in following 101 scenarios: 103 o One or more transit LSRs along ELI/EL imposed LSP do not perform 104 ECMP load balancing based on EL (hashes based on "keys" including 105 IP destination address). This scenario is not only possible but 106 quite common due transit LSRs not implementing [RFC6790] or 107 transit LSRs implementing [RFC6790] but not implementing suggested 108 transit LSR behavior in Section 4.3 of [RFC6790]. 110 o Two or more LSPs stitched together with at least one LSP being ELI 111 /EL imposing LSP. Such scenarios are described in 112 [I-D.ravisingh-mpls-el-for-seamless-mpls]. 114 These scenarios will be quite common because every deployment of 115 [RFC6790] will invariably end up with nodes that support ELI/EL and 116 nodes that do not. There will typically be areas that support ELI/EL 117 and areas that do not. 119 As pointed out in [RFC6790] the procedures of [RFC4379] with respect 120 to multipath information type {9} are incomplete. However [RFC6790] 121 does not actually update [RFC4379]. Further the specific EL location 122 is not clearly defined, particularly in the case of FAT Pseudowires 123 [RFC6391]. Herein is defined a new FEC Stack sub-TLV for the Entropy 124 Label. Section 3 of this document updates the procedures for 125 multipath information type {9}. 127 2. Overview 129 [RFC4379] describes LSP traceroute as an operation performed through 130 initiating LSR sending LSP Ping packet (LSP echo request) with 131 incrementing TTL, starting with TTL of one. Initiating LSR discovers 132 and exercises ECMP by obtaining multipath information from each 133 transit LSR and using specific destination IP address or specific 134 entropy label. 136 LSP Ping initiating LSR sends LSP echo request with multipath 137 information. This multipath information is described in DSMAP/DDMAP 138 TLV of echo request, and can contain set of IP addresses or set of 139 labels today. Multipath information types {2, 4, 8} carry set of IP 140 addresses and multipath information type {9} carries set of labels. 141 Responder LSR (receiver of LSP echo request) is to determine subset 142 of initiator specified multipath information which load balances to 143 each downstream (outgoing interface). Responder LSR sends LSP echo 144 reply with resulting multipath information per downstream (outgoing 145 interface) back to the initiating LSR. Initiating LSR is then able 146 to use specific IP destination address or specific label to exercise 147 specific ECMP path on the responder LSR. 149 Current behavior is problematic in following scenarios: 151 o Initiating LSR sends IP multipath information, but responder LSR 152 load balances on labels. 154 o Initiating LSR sends label multipath information, but responder 155 LSR load balances on IP addresses. 157 o Initiating LSR sends any of existing multipath information to ELI/ 158 EL imposing LSR, but initiating LSR can only continue to discover 159 and exercise specific path of ECMP if ELI/EL imposing LSR responds 160 with both IP addresses and associated EL corresponding to each IP 161 address. This is because: 163 * ELI/EL imposing LSR that is a stitching point will load balance 164 based on IP address. 166 * Downstream LSR(s) of ELI/EL imposing LSR may load balance based 167 on ELs. 169 o Initiating LSR sends any of existing multipath information to ELI/ 170 EL imposing LSR, but initiating LSR can only continue to discover 171 and exercise specific path of ECMP if ELI/EL imposing LSR responds 172 with both labels and associated EL corresponding to label. This 173 is because: 175 * ELI/EL imposing LSR that is a stitching point will load balance 176 based on EL from previous LSP and imposes new EL. 178 * Downstream LSR(s) of ELI/EL imposing LSR may load balance based 179 on new ELs. 181 The above scenarios point to how the existing multipath information 182 is insufficient when LSP traceroute is operated on an LSP with 183 Entropy Labels described by [RFC6790]. Therefore, this document 184 defines a multipath information type to be used in the DSMAP/DDMAP of 185 LSP echo request/reply packets in Section 8. 187 In addition, responder LSR can reply with empty multipath information 188 if no IP address set or label set from received multipath information 189 matched load balancing to a downstream. Empty return is also 190 possible if initiating LSR sends multipath information of one type, 191 IP address or label, but responder LSR load balances on the other 192 type. To disambiguate between the two results, this document 193 introduces new flags in the DSMAP/DDMAP TLV to allow responder LSR to 194 describe the load balance technique being used. 196 It is required that all LSRs along the LSP understand new flags as 197 well as new multipath information type. It is also required that 198 initiating LSR can select both IP destination address and label to 199 use on transmitting LSP echo request packets. Two additional DS 200 Flags are defined for the DSMAP and DDMAP TLVs in Section 7. 202 3. Multipath Type 9 204 [RFC4379] defined multipath type {9} for tracing of LSPs where label 205 based load-balancing is used. However, as pointed out in [RFC6790], 206 the procedures for using this type are incomplete. First, the 207 specific location of the label was not defined. What was assumed, 208 but not spelled out, was that the presence of multipath type {9} 209 meant the responder should act as if the payload of the received 210 packet were non-IP and that the bottom-of-stack label should be 211 replaced by the values indicated by multipath type {9} to determine 212 their respective out-going interfaces. 214 Further, with the introduction of [RFC6790], entropy labels may now 215 appear anywhere in a label stack. 217 This section defines to which labels multipath type {9} can apply. 218 Additionally it defines procedures for tracing pseudowires and flow- 219 aware pseudowires. These procedures pertain to the use of multipath 220 information type {9} as well as type {10}. 222 Section 6 defines a new FEC-Stack sub-TLV to indicate and entropy 223 label. Multipath type {9} applies exclusively to this sub-TLV. Any 224 LSP Ping message containing a DD-MAP or DS-MAP with multipath type 225 {9} MUST include an EL_FEC at the bottom of the FEC-Stack. 227 When an MPLS echo request message is received containing a FEC-Stack 228 with an EL-FEC at the bottom of the FEC stack and is not preceded by 229 an entropy label, the responder must behave (for load balancing 230 purposes) as if the first word of the message were a Pseudowire 231 Control Word. 233 In order to trace a non-FAT pseudowire, instead of including the 234 appropriate PW-FEC in the FEC-Stack, an EL-FEC is included. Tracing 235 in this way will cause compliant routers to return the proper 236 outgoing interface. Note that this procedure only traces to the end 237 of the MPLS transport LSP (e.g. LDP and/or RSVP). To actually verify 238 the PW-FEC or in the case of a MS-PW, to determine the next 239 pseudowire label value, the initiator MUST repeat that step of the 240 trace, (i.e., repeating the TTL value used) but with the FEC-Stack 241 modified to contain the appropriate PW-FEC. 243 In order to trace a FAT pseudowire, the initiator includes an EL-FEC 244 at the bottom of the FEC-Stack and pushes the appropriate PW-FEC onto 245 the FEC-Stack. 247 4. Initiating LSR Procedures 249 In order to facilitate the flow of the following text we speak in 250 terms of a boolean called EL_LSP maintained by the initiating LSR. 251 This value controls the multipath information type to be used in 252 transmitted echo request packets. When the initiating LSR is 253 transmitting an echo request packet with DSMAP/DDMAP with a non-zero 254 multipath information type, then EL_LSP boolean MUST be consulted to 255 determine the multipath information type to use. 257 In addition to procedures described in [RFC4379] as updated by 258 Section 3 and [RFC6424], initiating LSR MUST operate with following 259 procedures. 261 o When initiating LSR is IP based load balancer (not imposing ELI/ 262 EL), initialize EL_LSP=False. 264 o When initiating LSR imposes ELI/EL, initialize EL_LSP=True. 266 o When initiating LSR is transmitting non-zero multipath information 267 type: 269 If (EL_LSP) initiating LSR MUST use multipath information type 270 {10}. 272 Else initiating LSR MUST use multipath information type {2, 4, 273 8, 9}. 275 o When initiating LSR is transmitting multipath information type 276 {10}, both "IP Multipath Information" and "Label Multipath 277 Information" MUST be included, and "IP Associated Label Multipath 278 Information" MUST be omitted (NULL). 280 o When initiating LSR receives echo reply with {L=0, E=1} in DS 281 flags with valid contents, set EL_LSP=True. 283 In following conditions, initiating LSR may have lost the ability to 284 exercise specific ECMP paths. Initiating LSR MAY continue with "best 285 effort". 287 o Received echo reply contains empty multipath information. 289 o Received echo reply contains {L=0, E=} DS flags, but does not 290 contain IP multipath information. 292 o Received echo reply contains {L=1, E=} DS flags, but does not 293 contain label multipath information. 295 o Received echo reply contains {L=, E=1} DS flags, but does not 296 contain associated label multipath information. 298 o IP multipath information types {2, 4, 8} sent, and received echo 299 reply with {L=1, E=0} in DS flags. 301 o Multipath information type {10} sent, and received echo reply with 302 multipath information type other than {10}. 304 5. Responder LSR Procedures 306 Common Procedures: Responder LSR receiving LSP echo request packet 307 with multipath information type {10} MUST validate following 308 contents. Any deviation MUST result in responder LSR to consider the 309 packet as malformed and return code 1 (Malformed echo request 310 received) in LSP echo reply packet. 312 o IP multipath information MUST be included. 314 o Label multipath information MUST be included. 316 o IP associated label multipath information MUST be omitted (NULL). 318 Following subsections describe expected responder LSR procedures when 319 echo reply is to include DSMAP/DDMAP TLVs, based on local load 320 balance technique being employed. In case responder LSR performs 321 deviating load balance techniques per downstream basis, appropriate 322 procedures matching to each downstream load balance technique MUST be 323 operated. 325 5.1. IP Based Load Balancer & Not Imposing ELI/EL 327 o Responder MUST set {L=0, E=0} in DS flags. 329 o If multipath information type {2, 4, 8} is received, responder 330 MUST comply with [RFC4379]/[RFC6424]. 332 o If multipath information type {9} is received, responder MUST 333 reply with multipath type {0}. 335 o If multipath information type {10} is received, responder MUST 336 reply with multipath information type {10}. "Label Multipath 337 Information" and "Associated Label Multipath Information" sections 338 MUST be omitted (NULL). If no matching IP address is found, then 339 "IPMultipathType" field MUST be set to multipath information type 340 {0} and "IP Multipath Information" section MUST also be omitted 341 (NULL). If at least one matching IP address is found, then 342 "IPMultipathType" field MUST be set to appropriate multipath 343 information type {2, 4, 8} and "IP Multipath Information" section 344 MUST be included. 346 5.2. IP Based Load Balancer & Imposing ELI/EL 348 o Responder MUST set {L=0, E=1} in DS flags. 350 o If multipath information type {9} is received, responder MUST 351 reply with multipath type {0}. 353 o If multipath type {2, 4, 8, 10} is received, responder MUST 354 respond with multipath type {10}. "Label Multipath Information" 355 section MUST be omitted (NULL). IP address set specified in 356 received IP multipath information MUST be used to determine the 357 returning IP/Label pairs. If received multipath information type 358 was {10}, received "Label Multipath Information" sections MUST NOT 359 be used to determine the associated label portion of returning IP/ 360 Label pairs. If no matching IP address is found, then 361 "IPMultipathType" field MUST be set to multipath information type 362 {0} and "IP Multipath Information" section MUST be omitted (NULL). 363 In addition, "Assoc Label Multipath Length" MUST be set to 0, and 364 "Associated Label Multipath Information" section MUST also be 365 omitted (NULL). If at least one matching IP address is found, 366 then "IPMultipathType" field MUST be set to appropriate multipath 367 information type {2, 4, 8} and "IP Multipath Information" section 368 MUST be included. In addition, "Associated Label Multipath 369 Information" section MUST be populated with list of labels 370 corresponding to each IP address specified in "IP Multipath 371 Information" section. "Assoc Label Multipath Length" MUST be set 372 to appropriate value. 374 5.3. Label Based Load Balancer & Not Imposing ELI/EL 376 o Responder MUST set {L=1, E=0} in DS flags. 378 o If multipath information type {2, 4, 8} is received, responder 379 MUST reply with multipath type {0}. 381 o If multipath information type {9} is received, responder MUST 382 comply with [RFC4379] /[RFC6424] as updated by Section 3. 384 o If multipath information type {10} is received, responder MUST 385 reply with multipath information type {10}. "IP Multipath 386 Information" and "Associated Label Multipath Information" sections 387 MUST be omitted (NULL). If no matching label is found, then 388 "LbMultipathType" field MUST be set to multipath information type 389 {0} and "Label Multipath Information" section MUST also be omitted 390 (NULL). If at least one matching label is found, then 391 "LbMultipathType" field MUST be set to appropriate multipath 392 information type {9} and "Label Multipath Information" section 393 MUST be included. 395 5.4. Label Based Load Balancer & Imposing ELI/EL 397 o Responder MUST set {L=1, E=1} in DS flags. 399 o If multipath information type {2, 4, 8} is received, responder 400 MUST reply with multipath type {0}. 402 o If multipath type {9, 10} is received, responder MUST respond with 403 multipath type {10}. "IP Multipath Information" section MUST be 404 omitted (NULL). Label set specified in received label multipath 405 information MUST be used to determine the returning Label/Label 406 pairs. If received multipath information type was {10}, received 407 "Label Multipath Information" sections MUST NOT be used to 408 determine the associated label portion of returning Label/Label 409 pairs. If no matching label is found, then "LbMultipathType" 410 field MUST be set to multipath information type {0} and "Label 411 Multipath Information" section MUST be omitted (NULL). In 412 addition, "Assoc Label Multipath Length" MUST be set to 0, and 413 "Associated Label Multipath Information" section MUST also be 414 omitted (NULL). If at least one matching label is found, then 415 "LbMultipathType" field MUST be set to appropriate multipath 416 information type {9} and "Label Multipath Information" section 417 MUST be included. In addition, "Associated Label Multipath 418 Information" section MUST be populated with list of labels 419 corresponding to each label specified in "Label Multipath 420 Information" section. "Assoc Label Multipath Length" MUST be set 421 to appropriate value. 423 5.5. FAT MS-PW Stitching LSR 425 MS-PW stitching LSR that xconnects flow-aware pseudowires behaves in 426 one of two ways: 428 o Load balances on previous flow label, and carries over same flow 429 label. For this case, stitching LSR is to behave as procedures 430 described in Section 5.3. 432 o Load balances on previous flow label, and replaces flow label with 433 newly computed. For this case, stitching LSR is to behave as 434 procedures described in Section 5.4. 436 6. Entropy Label FEC 438 Entropy Label Indicator (ELI) is a reserved label that has no 439 explicit FEC associated, and has label value 7 assigned from the 440 reserved range. Use Nil FEC as Target FEC Stack sub-TLV to account 441 for ELI in a Target FEC Stack TLV. 443 Entropy Label (EL) is a special purpose label with label value being 444 discretionary (i.e. label value may not be from the reserved range). 445 For LSP verification mechanics to perform its purpose, it is 446 necessary for a Target FEC Stack sub-TLV to clearly describe EL, 447 particularly in the scenario where label stack does not carry ELI 448 (ex: FAT-PW [RFC6391]). Therefore, this document defines a EL FEC to 449 allow a Target FEC Stack sub-TLV to be added to the Target FEC Stack 450 to account for EL. 452 The Length is 4. Labels are 20-bit values treated as numbers. 454 0 1 2 3 455 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 1 456 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 457 | Label | MBZ | 458 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 460 Label is the actual label value inserted in the label stack; the MBZ 461 fields MUST be zero when sent and ignored on receipt. 463 7. DS Flags: L and E 465 Two flags, L and E, are added in DS Flags field of the DSMAP/DDMAP 466 TLVs. Both flags MUST NOT be set in echo request packets when 467 sending, and ignored when received. Zero, one or both new flags MUST 468 be set in echo reply packets. 470 DS Flags 471 -------- 473 0 1 2 3 4 5 6 7 474 +-+-+-+-+-+-+-+-+ 475 | MBZ |L|E|I|N| 476 +-+-+-+-+-+-+-+-+ 478 Flag Name and Meaning 479 ---- ---------------- 480 L Label based load balance indicator 481 This flag MUST be set to zero in the echo request. LSR 482 which performs load balancing on a label MUST set this 483 flag in the echo reply. LSR which performs load 484 balancing on IP MUST NOT set this flag in the echo 485 reply. 487 E ELI/EL imposer indicator 488 This flag MUST be set to zero in the echo request. LSR 489 which imposes ELI/EL MUST set this flag in the echo 490 reply. LSR which does not impose ELI/EL MUST NOT set 491 this flag in the echo reply. 493 Two flags result in four load balancing techniques which echo reply 494 generating LSR can indicate: 496 o {L=0, E=0} LSR load balances based on IP and does not impose ELI/ 497 EL. 499 o {L=0, E=1} LSR load balances based on IP and imposes ELI/EL. 501 o {L=1, E=0} LSR load balances based on label and does not impose 502 ELI/EL. 504 o {L=1, E=1} LSR load balances based on label and imposes ELI/EL. 506 8. New Multipath Information Type: 10 508 One new multipath information type is added to be used in DSMAP/DDMAP 509 TLVs. New multipath type has value of 10. 511 Key Type Multipath Information 512 --- ---------------- --------------------- 513 10 IP and label set IP addresses and label prefixes 515 Multipath type 10 is comprised of three sections. One section to 516 describe IP address set. One section to describe label set. One 517 section to describe another label set which associates to either IP 518 address set or label set specified in the other section. 520 Multipath information type 10 has following format: 522 0 1 2 3 523 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 1 524 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 525 |IPMultipathType| Reserved(MBZ) | IP Multipath Length | 526 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 527 ~ ~ 528 | (IP Multipath Information) | 529 ~ ~ 530 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 531 |LbMultipathType| Reserved(MBZ) | Label Multipath Length | 532 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 533 ~ ~ 534 | (Label Multipath Information) | 535 ~ ~ 536 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 537 | Reserved(MBZ) | Assoc Label Multipath Length | 538 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 539 ~ ~ 540 | (Associated Label Multipath Information) | 541 ~ ~ 542 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 544 o IP Multipath Information 546 This section reuses IP multipath information from [RFC4379]. 547 Specifically, values {0, 2, 4, 8} can be used. 549 o Label Multipath Information 551 This section reuses label multipath information from [RFC4379]. 552 Specifically, values {0, 9} can be used. 554 o Associated Label Multipath Information 556 "Assoc Label Multipath Length" is a 16 bit field of multipath 557 information which indicates length in octets of the associated 558 label multipath information. 560 "Associated Label Multipath Information" is a list of labels 561 with each label described in 24 bits. This section MUST be 562 omitted (NULL) in an MPLS Echo Request message. A midpoint 563 which imposes ELI/EL labels SHOULD include "Assoc Label 564 Multipath Information" in its MPLS Echo Reply message, along 565 with either "IP Multipath Information" or "Label Multipath 566 Information". Each specified associated label described in 567 this section maps to specific IP address OR label described in 568 the "IP Multipath Information" section or "Label Multipath 569 Information" section. For example, if 3 IP addresses are 570 specified in the "IP Multipath Information" section, then there 571 MUST be 3 labels described in this section. First label maps 572 to the lowest IP address specified, second label maps to the 573 second lowest IP address specified and third label maps to the 574 third lowest IP address specified. 576 9. Unsupported Cases 578 There are couple of scenarios where LSP path tracing mechanics are 579 not supported in this draft revision. 581 o When one or more LSP transit node(s) performs label based load 582 balancing on a label that is not bottom-of-stack label when 583 Entropy Label Indicator is not included. 585 o When one or more LSP transit node(s) performs label based load 586 balancing on a label other than Entropy Label when Entropy Label 587 Indicator and Entropy Label pair is included. 589 10. Security Considerations 591 Beyond those specified in [RFC4379], [RFC6424] and [RFC6790], there 592 are no further security measured required. 594 11. IANA Considerations 596 11.1. DS Flags 598 DS flags ... not maintained by IANA. Should it be? 600 11.2. Multipath Information Types 602 Multipath information types ... not maintained by IANA. Should it 603 be? 605 11.3. Entropy Label FEC 607 IANA is requested to assign a new sub-TLV from the "Sub-TLVs for TLV 608 Types 1 and 16" section from "TLVs" sub-registry within the "Multi- 609 Protocol Label Switching (MPLS) Label Switched Paths (LSPs) Ping 610 Parameters" registry. 612 Following value appears to be next available sub-TLV value. 613 Requesting IANA to allow specified value as early allocation. 615 Value Meaning Reference 616 ----- ------- --------- 617 26 Entropy Label FEC this document 619 12. Acknowledgements 621 TBD 623 13. Contributing Authors 625 Nagendra Kumar 626 Cisco Systems 627 Email: naikumar@cisco.com 629 14. References 631 14.1. Normative References 633 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 634 Requirement Levels", BCP 14, RFC 2119, March 1997. 636 [RFC4379] Kompella, K. and G. Swallow, "Detecting Multi-Protocol 637 Label Switched (MPLS) Data Plane Failures", RFC 4379, 638 February 2006. 640 [RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and 641 L. Yong, "The Use of Entropy Labels in MPLS Forwarding", 642 RFC 6790, November 2012. 644 14.2. Informative References 646 [I-D.ravisingh-mpls-el-for-seamless-mpls] 647 Singh, R., Shen, Y., and J. Drake, "Entropy label for 648 seamless MPLS", draft-ravisingh-mpls-el-for-seamless- 649 mpls-00 (work in progress), February 2013. 651 [RFC6391] Bryant, S., Filsfils, C., Drafz, U., Kompella, V., Regan, 652 J., and S. Amante, "Flow-Aware Transport of Pseudowires 653 over an MPLS Packet Switched Network", RFC 6391, November 654 2011. 656 [RFC6424] Bahadur, N., Kompella, K., and G. Swallow, "Mechanism for 657 Performing Label Switched Path Ping (LSP Ping) over MPLS 658 Tunnels", RFC 6424, November 2011. 660 Authors' Addresses 661 Nobo Akiya 662 Cisco Systems 664 Email: nobo@cisco.com 666 George Swallow 667 Cisco Systems 669 Email: swallow@cisco.com 671 Carlos Pignataro 672 Cisco Systems 674 Email: cpignata@cisco.com