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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 IPPM Working Group X. Min 3 Internet-Draft G. Mirsky 4 Intended status: Standards Track ZTE 5 Expires: June 21, 2019 L. Bo 6 China Telecom 7 December 18, 2018 9 Extended OAM to Carry In-situ OAM Capabilities 10 draft-xiao-ippm-ioam-conf-state-02 12 Abstract 14 This document describes an extension for OAM packets including MPLS 15 LSP Ping/Traceroute [RFC8029], ICMP Ping/Traceroute for SRv6 16 [I-D.ali-spring-srv6-oam] and SFC Ping/Traceroute 17 [I-D.ietf-sfc-multi-layer-oam], which can be used within an IOAM 18 domain, allowing the IOAM encapsulating node to acquire IOAM 19 capabilities of each IOAM transit node and/or IOAM decapsulating node 20 easily and dynamically. 22 Status of This Memo 24 This Internet-Draft is submitted in full conformance with the 25 provisions of BCP 78 and BCP 79. 27 Internet-Drafts are working documents of the Internet Engineering 28 Task Force (IETF). Note that other groups may also distribute 29 working documents as Internet-Drafts. The list of current Internet- 30 Drafts is at https://datatracker.ietf.org/drafts/current/. 32 Internet-Drafts are draft documents valid for a maximum of six months 33 and may be updated, replaced, or obsoleted by other documents at any 34 time. It is inappropriate to use Internet-Drafts as reference 35 material or to cite them other than as "work in progress." 37 This Internet-Draft will expire on June 21, 2019. 39 Copyright Notice 41 Copyright (c) 2018 IETF Trust and the persons identified as the 42 document authors. All rights reserved. 44 This document is subject to BCP 78 and the IETF Trust's Legal 45 Provisions Relating to IETF Documents 46 (https://trustee.ietf.org/license-info) in effect on the date of 47 publication of this document. Please review these documents 48 carefully, as they describe your rights and restrictions with respect 49 to this document. Code Components extracted from this document must 50 include Simplified BSD License text as described in Section 4.e of 51 the Trust Legal Provisions and are provided without warranty as 52 described in the Simplified BSD License. 54 Table of Contents 56 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 57 1.1. Conventions Used in This Document . . . . . . . . . . . . 3 58 1.1.1. Terminology . . . . . . . . . . . . . . . . . . . . . 3 59 1.1.2. Requirements Language . . . . . . . . . . . . . . . . 3 60 2. IOAM Capabilities Formats . . . . . . . . . . . . . . . . . . 4 61 2.1. IOAM Capabilities TLV . . . . . . . . . . . . . . . . . . 4 62 2.1.1. IOAM Tracing Capabilities sub-TLV . . . . . . . . . . 5 63 2.1.2. IOAM Proof of Transit Capabilities sub-TLV . . . . . 6 64 2.1.3. IOAM Edge-to-Edge Capabilities sub-TLV . . . . . . . 7 65 2.1.4. IOAM End-of-Domain sub-TLV . . . . . . . . . . . . . 9 66 3. Operational Guide . . . . . . . . . . . . . . . . . . . . . . 9 67 4. Security Considerations . . . . . . . . . . . . . . . . . . . 10 68 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 69 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10 70 7. Normative References . . . . . . . . . . . . . . . . . . . . 10 71 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 73 1. Introduction 75 The Data Fields for In-situ OAM (IOAM) [I-D.ietf-ippm-ioam-data] 76 defines data fields for IOAM which records OAM information within the 77 packet while the packet traverses a particular network domain, which 78 is called an IOAM domain. IOAM can be used to complement OAM 79 mechanisms based on, e.g., ICMP or other types of probe packets, and 80 IOAM mechanisms can be leveraged where mechanisms using, e.g., ICMP 81 do not apply or do not offer the desired results. 83 As specified in [I-D.ietf-ippm-ioam-data], within the IOAM-domain, 84 the IOAM data may be updated by network nodes that the packet 85 traverses. The device which adds an IOAM data container to the 86 packet to capture IOAM data is called the "IOAM encapsulating node", 87 whereas the device which removes the IOAM data container is referred 88 to as the "IOAM decapsulating node". Nodes within the domain which 89 are aware of IOAM data and read and/or write or process the IOAM data 90 are called "IOAM transit nodes". Both the IOAM encapsulating node 91 and the decapsulating node are referred to as domain edge devices, 92 which can be hosts or network devices. 94 In order to add accurate IOAM data container to the packet, the IOAM 95 encapsulating node needs to know IOAM capabilities at the IOAM 96 transit nodes and/or the IOAM decapsulating node in a whole, e.g., 97 how many IOAM transit nodes will add tracing data and what kinds of 98 data fields will be added. This document describes an extension for 99 OAM packets including MPLS LSP Ping/Traceroute [RFC8029], ICMP Ping/ 100 Traceroute for SRv6 [I-D.ali-spring-srv6-oam] and SFC Ping/Traceroute 101 [I-D.ietf-sfc-multi-layer-oam], which can be used within an IOAM 102 domain, allowing the IOAM encapsulating node to acquire IOAM 103 capabilities of each IOAM transit node and/or IOAM decapsulating node 104 easily and dynamically. 106 1.1. Conventions Used in This Document 108 1.1.1. Terminology 110 E2E: Edge to Edge 112 ICMP: Internet Control Message Protocol 114 IOAM: In-situ Operations, Administration, and Maintenance 116 LSP: Label Switched Path 118 MPLS: Multi-Protocol Label Switching 120 MTU: Maximum Transmission Unit 122 NTP: Network Time Protocol 124 OAM: Operations, Administration, and Maintenance 126 POSIX: Portable Operating System Interface 128 POT: Proof of Transit 130 PTP: Precision Time Protocol 132 SFC: Service Function Chain 134 SRv6: Segment Routing with IPv6 Data plane 136 TTL: Time to Live 138 1.1.2. Requirements Language 140 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 141 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 142 "OPTIONAL" in this document are to be interpreted as described in BCP 143 14 [RFC2119] [RFC8174] when, and only when, they appear in all 144 capitals, as shown here. 146 2. IOAM Capabilities Formats 148 2.1. IOAM Capabilities TLV 150 IOAM Capabilities uses TLV (Type-Length-Value tuple) which have the 151 following format: 153 0 1 2 3 154 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 1 155 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 156 | Type = IOAM Capabilities | Length | 157 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 158 | Namespace-IDs Length | Sub-TLVs Length | 159 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 160 . . 161 . List of Namespace-IDs . 162 . . 163 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 164 . . 165 . List of Sub-TLVs . 166 . . 167 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 169 Figure 1: IOAM Capabilities TLV 171 When this TLV is present in the echo request sent by an IOAM 172 encapsulating node, it means that the IOAM encapsulating node 173 requests the receiving node to reply with its IOAM capabilities. If 174 there is no IOAM capabilities to be reported by the receiving node, 175 then this TLV SHOULD be ignored by the receiving node. List of 176 Namespace-IDs MAY be included in this TLV of echo request, it means 177 that the IOAM encapsulating node requests only the IOAM capabilities 178 which matchs one of the Namespace-IDs. The Namespace-ID has the same 179 definition as what's specified in [I-D.ietf-ippm-ioam-data]. 181 When this TLV is present in the echo reply sent by an IOAM transit 182 node and/or an IOAM decapsulating node, it means that IOAM function 183 is enabled at this node and this TLV contains IOAM capabilities of 184 the sender. List of Namespace-IDs MAY be included in this TLV of 185 echo reply. It means that the IOAM capabilities included in this TLV 186 match one of the Namespace-IDs. If a List of Namespace-IDs is 187 present in the TLV of echo request, then the List of Namespace-IDs in 188 the TLV of echo reply MUST be a subset of that one. List of Sub-TLVs 189 which contain the IOAM capabilities SHOULD be included in this TLV of 190 the echo reply. Note that the IOAM encapsulating node or the IOAM 191 decapsulating node can also be an IOAM transit node. 193 Type is set to the value which indicates that it's an IOAM 194 Capabilities TLV. 196 Length is the length of the TLV's Value field in octets, Namespace- 197 IDs Length is the Length of the List of Namespace-IDs field in 198 octets, Sub-TLVs Length is the length of the List of Sub-TLVs field 199 in octets. 201 Value field of this TLV or any Sub-TLV is zero padded to align to a 202 4-octet boundary. Based on the data fields for IOAM specified in 203 [I-D.ietf-ippm-ioam-data], four kinds of Sub-TLVs are defined in this 204 document, and in an IOAM Capabilities TLV the same kind of Sub-TLV 205 can appear more times than one with different Namespace-ID. 207 2.1.1. IOAM Tracing Capabilities sub-TLV 209 0 1 2 3 210 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 1 211 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 212 | Sub-type = Tracing Conf Data | Length | 213 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 214 | IOAM-Trace-Type |F| Reserved | 215 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 216 | Namespace-ID | Egress_if_MTU | 217 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 218 | Egress_if_id (short or wide format) ...... | 219 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 221 Figure 2: IOAM Tracing Capabilities Sub-TLV 223 When this sub-TLV is present in the IOAM Capabilities TLV, it means 224 that the sending node is an IOAM transit node and IOAM tracing 225 function is enabled at this IOAM transit node. 227 Sub-type is set to the value which indicates that it's an IOAM 228 Tracing Capabilities sub-TLV. 230 Length is the length of the sub-TLV's Value field in octets, if 231 Egress_if_id is in the short format which is 16 bits long, it MUST be 232 set to 10, and if Egress_if_id is in the wide format which is 32 bits 233 long, it MUST be set to 12. 235 IOAM-Trace-Type field has the same definition as what's specified in 236 section 4.2 of [I-D.ietf-ippm-ioam-data]. 238 F bit is specified to indicate whether the pre-allocated trace or 239 incremental trace is enabled. F bit is set to 1 when pre-allocated 240 trace is enabled and set to 0 when the incremental trace is enabled. 241 The meaning and difference of pre-allocated trace and incremental 242 trace are described in section 4.1 of [I-D.ietf-ippm-ioam-data]. If 243 the IOAM encapsulating node receives different F bit value from 244 different IOAM transit node, then the IOAM encapsulating node will 245 reserve data space in the IOAM header for the IOAM transit node that 246 set F bit to 1, and the IOAM encapsulating node won't reserve data 247 space in the IOAM header for the IOAM transit node that set F bit to 248 0. 250 Reserved field is reserved for future use and MUST be set to zero. 252 Namespace-ID field has the same definition as what's specified in 253 section 4.2 of [I-D.ietf-ippm-ioam-data]. 255 Egress_if_MTU field has 16 bits and specifies the MTU of the egress 256 interface out of which the sending node would forward the received 257 echo request. 259 Egress_if_id field has 16 bits (in short format) or 32 bits (in wide 260 format) and specifies the identifier of the egress interface out of 261 which the sending node would forward the received echo request. 263 2.1.2. IOAM Proof of Transit Capabilities sub-TLV 265 0 1 2 3 266 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 1 267 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 268 | Sub-type = POT Conf Data | Length | 269 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 270 | Namespace-ID | IOAM-POT-Type |P|SoR|Reserved | 271 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 273 Figure 3: IOAM Proof of Transit Capabilities Sub-TLV 275 When this sub-TLV is present in the IOAM Capabilities TLV, it means 276 that the sending node is an IOAM transit node and IOAM proof of 277 transit function is enabled at this IOAM transit node. 279 Sub-type is set to the value which indicates that it's an IOAM Proof 280 of Transit Capabilities sub-TLV. 282 Length is the length of the sub-TLV's Value field in octets, and MUST 283 be set to 4. 285 Namespace-ID field has the same definition as what's specified in 286 section 4.3 of [I-D.ietf-ippm-ioam-data]. 288 IOAM-POT-Type field and P bit have the same definition as what's 289 specified in section 4.3 of [I-D.ietf-ippm-ioam-data]. If the IOAM 290 encapsulating node receives IOAM-POT-Type and/or P bit values from an 291 IOAM transit node that are different from its own, then the IOAM 292 encapsulating node MAY choose to abandon the proof of transit 293 function or to select one kind of IOAM-POT-Type and P bit, it's based 294 on the policy applied to the IOAM encapsulating node. 296 SoR field has two bits which means the size of "Random" and 297 "Cumulative" data, which are specified in section 4.3 of 298 [I-D.ietf-ippm-ioam-data]. This document defines SoR as follow: 300 0b00 means 64-bit "Random" and 64-bit "Cumulative" data. 302 0b01~0b11: Reserved for future standardization 304 Reserved field is reserved for future use and MUST be set to zero. 306 2.1.3. IOAM Edge-to-Edge Capabilities sub-TLV 308 0 1 2 3 309 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 1 310 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 311 | Sub-type = E2E Conf Data | Length | 312 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 313 | Namespace-ID | IOAM-E2E-Type | 314 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 315 |TSF|TSL| Reserved | Must Be Zero | 316 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 318 Figure 4: IOAM Edge-to-Edge Capabilities Sub-TLV 320 When this sub-TLV is present in the IOAM Capabilities TLV, it means 321 that the sending node is an IOAM decapsulating node and IOAM edge-to- 322 edge function is enabled at this IOAM decapsulating node. That is to 323 say, if the IOAM encapsulating node receives this sub-TLV, the IOAM 324 encapsulating node can determine that the node which sends this sub- 325 TLV is an IOAM decapsulating node. 327 Sub-type is set to the value which indicates that it's an IOAM Edge- 328 to-Edge Capabilities sub-TLV. 330 Length is the length of the sub-TLV's Value field in octets, and MUST 331 be set to 8. 333 Namespace-ID field has the same definition as what's specified in 334 section 4.4 of [I-D.ietf-ippm-ioam-data]. 336 IOAM-E2E-Type field has the same definition as what's specified in 337 section 4.4 of [I-D.ietf-ippm-ioam-data]. 339 TSF field specifies the timestamp format used by the sending node. 340 This document defines TSF as follow: 342 0b00: PTP timestamp format 344 0b01: NTP timestamp format 346 0b10: POSIX timestamp format 348 0b11: Reserved for future standardization 350 TSL field specifies the timestamp length used by the sending node. 351 This document defines TSL as follow: 353 When TSF field is set to 0b00 which indicates PTP timestamp 354 format: 356 0b00: 64-bit PTPv1 timestamp as defined in IEEE1588-2008 357 [IEEE1588v2] 359 0b01: 80-bit PTPv2 timestamp as defined in IEEE1588-2008 360 [IEEE1588v2] 362 0b10~0b11: Reserved for future standardization 364 When TSF field is set to 0b01 which indicates NTP timestamp 365 format: 367 0b00: 32-bit NTP timestamp as defined in NTPv4 [RFC5905] 369 0b01: 64-bit NTP timestamp as defined in NTPv4 [RFC5905] 371 0b10: 128-bit NTP timestamp as defined in NTPv4 [RFC5905] 373 0b11: Reserved for future standardization 375 When TSF field is set to 0b10 or 0b11, the TSL field would be 376 ignored. 378 Reserved field is reserved for future use and MUST be set to zero. 380 2.1.4. IOAM End-of-Domain sub-TLV 382 0 1 2 3 383 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 1 384 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 385 | Sub-type = End of Domain | Length | 386 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 387 | Namespace-ID | Must Be Zero | 388 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 390 Figure 5: IOAM End of Domain Sub-TLV 392 When this sub-TLV is present in the IOAM Capabilities TLV, it means 393 that the sending node is an IOAM decapsulating node. That is to say, 394 if the IOAM encapsulating node receives this sub-TLV, the IOAM 395 encapsulating node can determine that the node which sends this sub- 396 TLV is an IOAM decapsulating node. When the IOAM Edge-to-Edge 397 Capabilities sub-TLV is present in the IOAM Capabilities TLV sent by 398 the IOAM decapsulating node, the IOAM End-of-Domain sub-TLV doesn't 399 need to be present in the same IOAM Capabilities TLV, otherwise the 400 End-of-Domain sub-TLV MUST be present in the IOAM Capabilities TLV 401 sent by the IOAM decapsulating node. Since both the IOAM Edge-to- 402 Edge Capabilities sub-TLV and the IOAM End-of-Domain sub-TLV can be 403 used to indicate that the sending node is an IOAM decapsulating node, 404 it's recommended to include only the IOAM Edge-to-Edge Capabilities 405 sub-TLV if IOAM edge-to-edge function is enabled at this IOAM 406 decapsulating node. 408 Length is the length of the sub-TLV's Value field in octets, and MUST 409 be set to 4. 411 Namespace-ID field has the same definition as what's specified in 412 section 4.4 of [I-D.ietf-ippm-ioam-data]. 414 3. Operational Guide 416 Once the IOAM encapsulating node is triggered to acquire IOAM 417 capabilities of each IOAM transit node and/or IOAM decapsulating 418 node, the IOAM encapsulating node will send a batch of echo requests 419 that include the IOAM Capabilities TLV, first with TTL equal to 1 to 420 reach the nearest node which may be an IOAM transit node or not, then 421 with TTL equal to 2 to reach the second nearest node which also may 422 be an IOAM transit node or not, on the analogy of this to increase 1 423 to TTL every time the IOAM encapsulating node sends a new echo 424 request, until the IOAM encapsulating node receives echo reply sent 425 by the IOAM decapsulating node, which must contain the IOAM 426 Capabilities TLV including the IOAM Edge-to-Edge Capabilities sub-TLV 427 or the IOAM End-of-Domain sub-TLV. 429 The IOAM encapsulating node may be triggered by the device 430 administrator, the network management, the network controller, or 431 even the live user traffic, and the specific triggering mechanisms 432 are outside the scope of this document. 434 Each IOAM transit node and/or IOAM decapsulating node that receives 435 an echo request containing the IOAM Capabilities TLV will send an 436 echo reply to the IOAM encapsulating node, and within the echo reply, 437 there must be an IOAM Capabilities TLV containing one or more sub- 438 TLVs. The IOAM Capabilities TLV contained in the echo request would 439 be ignored by the receiving node that is unaware of IOAM. 441 4. Security Considerations 443 Knowledge of the state of the IOAM domain may be considered 444 confidential. Implementations SHOULD provide a means of filtering 445 the addresses to which echo reply messages, MPLS LSP Ping/Traceroute, 446 ICMP Ping/Traceroute for SRv6 or SFC Ping/Traceroute, may be sent. 448 5. IANA Considerations 450 This document has no IANA actions. 452 6. Acknowledgements 454 The authors appreciate the f2f discussion with Frank Brockners on 455 this document. 457 7. Normative References 459 [I-D.ali-spring-srv6-oam] 460 Ali, Z., Filsfils, C., Kumar, N., Pignataro, C., 461 faiqbal@cisco.com, f., Gandhi, R., Leddy, J., Matsushima, 462 S., Raszuk, R., daniel.voyer@bell.ca, d., Dawra, G., 463 Peirens, B., Chen, M., and G. Naik, "Operations, 464 Administration, and Maintenance (OAM) in Segment Routing 465 Networks with IPv6 Data plane (SRv6)", draft-ali-spring- 466 srv6-oam-02 (work in progress), October 2018. 468 [I-D.ietf-ippm-ioam-data] 469 Brockners, F., Bhandari, S., Pignataro, C., Gredler, H., 470 Leddy, J., Youell, S., Mizrahi, T., Mozes, D., Lapukhov, 471 P., Chang, R., daniel.bernier@bell.ca, d., and J. Lemon, 472 "Data Fields for In-situ OAM", draft-ietf-ippm-ioam- 473 data-04 (work in progress), October 2018. 475 [I-D.ietf-sfc-multi-layer-oam] 476 Mirsky, G., Meng, W., Khasnabish, B., and C. Wang, "Active 477 OAM for Service Function Chains in Networks", draft-ietf- 478 sfc-multi-layer-oam-00 (work in progress), November 2018. 480 [IEEE1588v2] 481 Institute of Electrical and Electronics Engineers, "IEEE 482 Std 1588-2008 - IEEE Standard for a Precision Clock 483 Synchronization Protocol for Networked Measurement and 484 Control Systems", IEEE Std 1588-2008, 2008, 485 . 488 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 489 Requirement Levels", BCP 14, RFC 2119, 490 DOI 10.17487/RFC2119, March 1997, 491 . 493 [RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch, 494 "Network Time Protocol Version 4: Protocol and Algorithms 495 Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010, 496 . 498 [RFC8029] Kompella, K., Swallow, G., Pignataro, C., Ed., Kumar, N., 499 Aldrin, S., and M. Chen, "Detecting Multiprotocol Label 500 Switched (MPLS) Data-Plane Failures", RFC 8029, 501 DOI 10.17487/RFC8029, March 2017, 502 . 504 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 505 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 506 May 2017, . 508 Authors' Addresses 509 Xiao Min 510 ZTE 511 Nanjing 512 China 514 Phone: +86 25 88016574 515 Email: xiao.min2@zte.com.cn 517 Greg Mirsky 518 ZTE 519 USA 521 Email: gregimirsky@gmail.com 523 Lei Bo 524 China Telecom 525 Beijing 526 China 528 Phone: +86 10 50902903 529 Email: leibo.bri@chinatelecom.cn