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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) == Unused Reference: 'I-D.schmutzer-bess-ple' is defined on line 538, but no explicit reference was found in the text == Outdated reference: A later version (-04) exists of draft-schmutzer-bess-ple-03 Summary: 0 errors (**), 0 flaws (~~), 3 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 MPLS Working Group R. Gandhi 3 Internet-Draft P. Brissette 4 Intended status: Standards Track Cisco Systems, Inc. 5 Expires: 18 July 2022 E. Leyton 6 Verizon Wireless 7 14 January 2022 9 Encapsulation of Simple TWAMP (STAMP) for Pseudowires in MPLS Networks 10 draft-gandhi-mpls-stamp-pw-01 12 Abstract 14 Pseudowires (PWs) are used in MPLS networks for various services 15 including carrying layer 2 and layer 3 data packets. This document 16 describes the procedure for encapsulation of the Simple Two-Way 17 Active Measurement Protocol (STAMP) defined in RFC 8762 and its 18 optional extensions defined in RFC 8972 for PWs in MPLS networks. 19 The procedure uses PW Generic Associated Channel (G-ACh) to 20 encapsulate the STAMP test packets with or without an IP/UDP header. 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 18 July 2022. 39 Copyright Notice 41 Copyright (c) 2022 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 (https://trustee.ietf.org/ 46 license-info) in effect on the date of publication of this document. 47 Please review these documents carefully, as they describe your rights 48 and restrictions with respect to this document. Code Components 49 extracted from this document must include Revised BSD License text as 50 described in Section 4.e of the Trust Legal Provisions and are 51 provided without warranty as described in the Revised BSD License. 53 Table of Contents 55 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 56 1.1. Requirements . . . . . . . . . . . . . . . . . . . . . . 3 57 2. Conventions Used in This Document . . . . . . . . . . . . . . 3 58 2.1. Requirements Language . . . . . . . . . . . . . . . . . . 4 59 2.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 4 60 2.3. Reference Topology . . . . . . . . . . . . . . . . . . . 4 61 3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 5 62 4. Session-Sender Test Packet . . . . . . . . . . . . . . . . . 6 63 4.1. Session-Sender Test Packet with IP/UDP Header . . . . . . 6 64 4.2. Session-Sender Test Packet without IP/UDP Header . . . . 8 65 5. Session-Reflector Test Packet . . . . . . . . . . . . . . . . 9 66 5.1. Session-Reflector Test Packet with IP/UDP Header . . . . 9 67 5.2. Session-Reflector Test Packet without IP/UDP Header . . . 11 68 6. Security Considerations . . . . . . . . . . . . . . . . . . . 12 69 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 70 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 71 8.1. Normative References . . . . . . . . . . . . . . . . . . 12 72 8.2. Informative References . . . . . . . . . . . . . . . . . 13 73 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 14 74 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14 76 1. Introduction 78 The Simple Two-way Active Measurement Protocol (STAMP) provides 79 capabilities for the measurement of various metrics in IP networks 80 [RFC8762] without the use of a control channel to pre-signal session 81 parameters. [RFC8972] defines optional extensions for STAMP. 83 Pseudowires (PWs) are used in MPLS networks for various services 84 including carrying layer 2 and layer 3 data packets [RFC6658]. The 85 PWs are bidirectional in nature. The PWs can be point-to-point or 86 point-to-multipoint. A PW Generic Associated Channel (G-ACh) 87 [RFC5586] provides a mechanism to transport Operations, 88 Administration, and Maintenance (OAM) and other control messages over 89 MPLS data plane. The G-ACh channel types identify the various OAM 90 messages being transported over the channel. 92 This document describes the procedure for encapsulation of the STAMP 93 defined in [RFC8762] and its optional extensions defined in [RFC8972] 94 for point-to-point PWs in MPLS networks. The procedure uses PW 95 Generic Associated Channel (G-ACh) to encapsulate the STAMP test 96 packets with or without an IP/UDP header. The procedure for point- 97 to-multipoint PWs will be added in future. 99 1.1. Requirements 101 The STAMP test packets need to be transmitted with the same MPLS 102 label stack that is used by the PW traffic to ensure proper 103 validation of underlay path taken by the actual PW traffic. Also, 104 the test packets need to follow the same ECMP path taken by the PW 105 traffic. The STAMP test packets may be encapsulated over the PW 106 associated channel with or without an IP/UDP header. 108 In case of MPLS Transport Profile (MPLS TP), the STAMP test packets 109 need to be tranmitted on the Generic Associated Channel without using 110 an IP header to have the same forwarding behavior as the data 111 traffic. 113 The requirements for the encapsulation of the STAMP test packets for 114 the PWs in MPLS networks can be summarized as follows: 116 o The PW associated channel MUST support STAMP test packets with IP/ 117 UDP header. 119 o The PW associated channel MUST support STAMP test packets without 120 IP/UDP header. 122 o The Session-Sender test packets MUST follow the same underlay path 123 taken by the traffic for the associated PW channel. 125 o The Session-Sender test packets MUST follow the same ECMP underlay 126 path taken by the traffic for the associated PW channel. 128 o The Session-Reflector test packets MAY follow the same reverse 129 underlay path taken by Session-Sender test packets. 131 o The Session-Reflector test packets MAY follow the same reverse ECMP 132 underlay path taken by Session-Sender test packets. 134 2. Conventions Used in This Document 135 2.1. Requirements Language 137 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 138 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 139 document are to be interpreted as described in [RFC2119] [RFC8174] 140 when, and only when, they appear in all capitals, as shown here. 142 2.2. Abbreviations 144 ECMP: Equal Cost Multi-Path. 146 G-ACh: Generic Associated Channel. 148 GAL: G-ACh Label. 150 HMAC: Hashed Message Authentication Code. 152 MPLS: Multiprotocol Label Switching. 154 OAM: Operations, Administration, and Maintenance. 156 PLE: Private Line Emulation. 158 PW: Pseudowires. 160 SHA: Secure Hash Algorithm. 162 STAMP: Simple Two-way Active Measurement Protocol. 164 TC: Traffic Class. 166 2.3. Reference Topology 168 In the Reference Topology shown in Figure 1, there exists a packet 169 pseudowire to transport data between LSRs S1 and R1. The STAMP 170 Session-Sender on LSR S1 initiates a Session-Sender test packet and 171 the STAMP Session-Reflector on LSR R1 transmits a reply test packet. 172 The reply test packet is transmitted to the STAMP Session-Sender on 173 the same path (same set of links and nodes) in the reverse direction 174 of the path taken towards the Session-Reflector. 176 |<-------- Pseudowire ------->| 177 | | 178 | T1 T2 | 179 | / \ | 180 +-------+ Test Packet +-------+ 181 | | - - - - - - - - - ->| | 182 | S1 |=====================| R1 | 183 | |<- - - - - - - - - - | | 184 +-------+ Reply Test Packet +-------+ 185 \ / 186 T4 T3 188 STAMP Session-Sender STAMP Session-Reflector 190 T1, T2, T3, T4: Timestamps as described in [RFC8762] 192 Figure 1: Reference Topology 194 3. Overview 196 The STAMP Session-Sender and Session-Reflector test packets defined 197 in [RFC8972] are transmitted over the PWs in MPLS networks. The base 198 STAMP test packets can be encapsulated using IP/UDP header and may 199 use Destination UDP port 862 [RFC8762]. 201 The STAMP test packets are encapsulated with MPLS header using the 202 same label stack as the PW traffic and the PW G-ACh header. The 203 encapsulation allows the STAMP test packets to follow the same path 204 as the PW traffic, and provide the same ECMP path selection on the 205 intermediate nodes. 207 There are two ways in which STAMP test packets may be encapsulated 208 over a PW associated channel, either using an IP/UDP header or 209 without using an IP/UDP header. 211 For encapsulating the STAMP test packets over a PW associated channel 212 with an IP/UDP header, IPv4 and IPv6 G-ACh types [RFC4385] are used 213 for both Session-Sender and Session-Reflector test packets. The 214 destination UDP port numbers in the Session-Sender and Session- 215 Reflector test packets discriminate the test packets. The IP version 216 (IPv4 or IPv6) MUST match the IP version used for signaling for 217 dynamically established PWs or MUST be configured for statically 218 provisioned PWs. 220 For encapsulating the STAMP test packets over a PW associated channel 221 without an IP/UDP header, two new G-ACh types are defined in this 222 document, one for the Session-Sender test packets and one for the 223 Session-Reflector test packets. The different G-ACh types are 224 required for the Session-Sender and Session-Reflector test packets as 225 the STAMP test packet formats do not have a way to discriminate them. 227 The Time to Live (TTL)/Hop Limit (HL) and Generalized TTL Security 228 Mechanism (GTSM) procedures from [RFC5082] apply to this 229 encapsulation, and hence the TTL/HL is set to 255. 231 The G-ACh label (GAL) [RFC5586] is not added in the MPLS label stack. 233 4. Session-Sender Test Packet 235 4.1. Session-Sender Test Packet with IP/UDP Header 237 The content of an example STAMP Session-Sender test packet 238 encapsulated over a PW associated channel using an IP/UDP header is 239 shown in Figure 2. The STAMP G-ACh header [RFC5586] with G-ACh MUST 240 immediately follow the bottom of the MPLS label stack. The payload 241 contains the STAMP Session-Sender test packet defined in [RFC8972]. 243 0 1 2 3 244 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 1 245 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 246 | Label(1) | TC |S| TTL | 247 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 248 . . 249 . . 250 . . 251 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 252 | PW Label | TC |1| TTL | 253 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 254 |0 0 0 1|Version| Reserved | IPv4 (0x0021) or IPv6 (0x0057)| 255 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 256 | IP Header | 257 . Source IP Address = Session-Sender IPv4 or IPv6 Address . 258 . Destination IP Address=Session-Reflector IPv4 or IPv6 Address. 259 . . 260 +---------------------------------------------------------------+ 261 | UDP Header | 262 . Source Port = As chosen by Session-Sender . 263 . Destination Port = User-configured Destination Port | 862 . 264 . . 265 +---------------------------------------------------------------+ 266 | Payload = Test Packet as specified in Section 3 of RFC 8972 | 267 . in Figure 1 and Figure 3 . 268 . . 269 +---------------------------------------------------------------+ 270 | Optional STAMP TLVs defined in RFC 8972 | 271 . . 272 +---------------------------------------------------------------+ 274 Figure 2: Example Session-Sender Test Packet with IP/UDP Header 276 The STAMP Session-Sender test packet G-ACh header contains following 277 fields: 279 Version: The Version field is set to 0, as defined in [RFC4385]. 281 Reserved: Reserved Bits MUST be set to zero upon transmission and 282 ignored upon receipt. 284 Channel Type: G-ACh channel type for IPv4 header (0x0021) or IPv6 285 header (0x0057) [RFC4385]. 287 4.2. Session-Sender Test Packet without IP/UDP Header 289 The content of an example STAMP Session-Sender test packet 290 encapsulated over a PW associated channel without using an IP/UDP 291 header is shown in Figure 3. The STAMP G-ACh header [RFC5586] with 292 new STAMP Session-Sender G-ACh type (value TBD1) MUST immediately 293 follow the bottom of the MPLS label stack. The payload contains the 294 STAMP Session-Sender test packet defined in [RFC8972]. 296 0 1 2 3 297 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 1 298 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 299 | Label(1) | TC |S| TTL | 300 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 301 . . 302 . . 303 . . 304 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 305 | PW Label | TC |1| TTL | 306 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 307 |0 0 0 1|Version| Reserved | STAMP Sender G-ACh (TBD1) | 308 +---------------------------------------------------------------+ 309 | Payload = Test Packet as specified in Section 3 of RFC 8972 | 310 . in Figure 1 and Figure 3 . 311 . . 312 +---------------------------------------------------------------+ 313 | Optional STAMP TLVs defined in RFC 8972 | 314 . . 315 +---------------------------------------------------------------+ 317 Figure 3: Example Session-Sender Test Packet without IP/UDP Header 319 The STAMP Session-Sender test packet G-ACh header contains following 320 fields: 322 Version: The Version field is set to 0, as defined in [RFC4385]. 324 Reserved: Reserved Bits MUST be set to zero upon transmission and 325 ignored upon receipt. 327 Channel Type: G-ACh channel type for STAMP Session-Sender packet 328 (TBD1). 330 5. Session-Reflector Test Packet 332 The STAMP Session-Reflector reply test packet is sent on the same 333 path in the reverse direction of a bidirectional PW. The STAMP test 334 packet can be sent using an MPLS header with or without IP/UDP 335 header. The Session-Reflector test packet is sent with an IP/UDP 336 header if the Session-Sender test packet is received with an IP/UDP 337 header, otherwise, it is sent without an IP/UDP header. 339 5.1. Session-Reflector Test Packet with IP/UDP Header 341 The content of an example STAMP Session-Reflector test packet 342 encapsulated over a PW associated channel using an IP/UDP header is 343 shown in Figure 4. The STAMP G-ACh header [RFC5586] with G-ACh MUST 344 immediately follow the bottom of the MPLS label stack. The payload 345 contains the STAMP Session-Reflector test packet defined in 346 [RFC8972]. 348 The STAMP Session-Reflector reply test packet MUST use the IP/UDP 349 information from the received test packet when an IP/UDP header is 350 present in the received test packet. 352 0 1 2 3 353 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 1 354 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 355 | Label(1) | TC |S| TTL | 356 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 357 . . 358 . . 359 . . 360 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 361 | PW Label | TC |1| TTL | 362 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 363 |0 0 0 1|Version| Reserved | IPv4 (0x0021) or IPv6 (0x0057)| 364 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 365 | IP Header | 366 . Source IP Address = Session-Reflector IPv4 or IPv6 Address . 367 . Destination IP Address . 368 . = Source IP Address from Received Test Packet . 369 . . 370 +---------------------------------------------------------------+ 371 | UDP Header | 372 . Source Port = As chosen by Session-Reflector . 373 . Destination Port = Source Port from Received Test Packet . 374 . . 375 +---------------------------------------------------------------+ 376 | Payload = Test Packet as specified in Section 3 of RFC 8972 | 377 . in Figure 2 and Figure 4 . 378 . . 379 +---------------------------------------------------------------+ 380 | Optional STAMP TLVs defined in RFC 8972 | 381 . . 382 +---------------------------------------------------------------+ 384 Figure 4: Example Session-Reflector Test Packet with IP/UDP Header 386 The STAMP Session-Reflector test packet G-ACh header contains 387 following fields: 389 Version: The Version field is set to 0, as defined in [RFC4385]. 391 Reserved: Reserved Bits MUST be set to zero upon transmission and 392 ignored upon receipt. 394 Channel Type: G-ACh channel type for IPv4 header (0x0021) or IPv6 395 header (0x0057) [RFC4385]. 397 5.2. Session-Reflector Test Packet without IP/UDP Header 399 The content of an example STAMP Session-Reflector test packet 400 encapsulated over a PW associated channel without using an IP/UDP 401 header is shown in Figure 5. The STAMP G-ACh header [RFC5586] with 402 new STAMP Session-Reflector G-ACh type (value TBD2) MUST immediately 403 follow the bottom of the MPLS label stack. The payload contains the 404 STAMP Session-Reflector test packet defined in [RFC8972]. 406 The STAMP Session-Reflector reflects the test packet back to the 407 Session-Sender using the same channel of the reverse direction of the 408 PW on which it was received. The Session-Reflector has enough 409 information to reflect the test packet received by it to the Session- 410 Sender using the PW context. 412 0 1 2 3 413 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 1 414 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 415 | Label(1) | TC |S| TTL | 416 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 417 . . 418 . . 419 . . 420 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 421 | PW Label | TC |1| TTL | 422 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 423 |0 0 0 1|Version| Reserved | STAMP Reflector G-ACh (TBD2) | 424 +---------------------------------------------------------------+ 425 | Payload = Test Packet as specified in Section 3 of RFC 8972 | 426 . in Figure 2 and Figure 4 . 427 . . 428 +---------------------------------------------------------------+ 430 Figure 5: Example Session-Reflector Test Packet without IP/UDP Header 432 The STAMP Session-Reflector test packet G-ACh header contains 433 following fields: 435 Version: The Version field is set to 0, as defined in [RFC4385]. 437 Reserved: Reserved Bits MUST be set to zero upon transmission and 438 ignored upon receipt. 440 Channel Type: G-ACh channel type for STAMP Session-Reflector packet 441 (TBD2). 443 6. Security Considerations 445 The usage of STAMP protocol is intended for deployment in limited 446 domains [RFC8799]. As such, it assumes that a node involved in STAMP 447 protocol operation has previously verified the integrity of the path 448 and the identity of the far-end STAMP Session-Reflector. 450 If desired, attacks can be mitigated by performing basic validation 451 and sanity checks, at the STAMP Session-Sender, of the counter or 452 timestamp fields in received reply test packets. The minimal state 453 associated with these protocols also limits the extent of disruption 454 that can be caused by a corrupt or invalid packet to a single test 455 cycle. 457 Use of HMAC-SHA-256 in the authenticated mode protects the data 458 integrity of the test packets. Cryptographic measures may be 459 enhanced by the correct configuration of access-control lists and 460 firewalls. 462 The security considerations specified in [RFC8762] and [RFC8972] also 463 apply to the procedure described in this document. Specifically, the 464 message integrity protection using HMAC, as defined in [RFC8762] 465 Section 4.4, also apply to the procedure described in this document. 467 Routers that support G-ACh are subject to the same security 468 considerations as defined in [RFC4385] and [RFC5586]. 470 7. IANA Considerations 472 IANA maintains G-ACh Type Registry (see 473 https://www.iana.org/assignments/g-ach-parameters/g-ach- 474 parameters.xhtml). IANA is requested to allocate values for the 475 STAMP G-ACh Types from "MPLS Generalized Associated Channel (G-ACh) 476 Types (including Pseudowire Associated Channel Types)" registry. 478 +=======+====================================+===============+ 479 | Value | Description | Reference | 480 +=======+====================================+===============+ 481 | TBD1 | STAMP Session-Sender G-ACh Type | This document | 482 +-------+------------------------------------+---------------+ 483 | TBD2 | STAMP Session-Reflector G-ACh Type | This document | 484 +-------+------------------------------------+---------------+ 486 Table 1: STAMP G-ACh Type 488 8. References 490 8.1. Normative References 492 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 493 Requirement Levels", BCP 14, RFC 2119, 494 DOI 10.17487/RFC2119, March 1997, 495 . 497 [RFC4385] Bryant, S., Swallow, G., Martini, L., and D. McPherson, 498 "Pseudowire Emulation Edge-to-Edge (PWE3) Control Word for 499 Use over an MPLS PSN", RFC 4385, DOI 10.17487/RFC4385, 500 February 2006, . 502 [RFC5586] Bocci, M., Ed., Vigoureux, M., Ed., and S. Bryant, Ed., 503 "MPLS Generic Associated Channel", RFC 5586, 504 DOI 10.17487/RFC5586, June 2009, 505 . 507 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 508 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 509 May 2017, . 511 [RFC8762] Mirsky, G., Jun, G., Nydell, H., and R. Foote, "Simple 512 Two-Way Active Measurement Protocol", RFC 8762, 513 DOI 10.17487/RFC8762, March 2020, 514 . 516 [RFC8972] Mirsky, G., Min, X., Nydell, H., Foote, R., Masputra, A., 517 and E. Ruffini, "Simple Two-Way Active Measurement 518 Protocol Optional Extensions", RFC 8972, 519 DOI 10.17487/RFC8972, January 2021, 520 . 522 8.2. Informative References 524 [RFC5082] Gill, V., Heasley, J., Meyer, D., Savola, P., Ed., and C. 525 Pignataro, "The Generalized TTL Security Mechanism 526 (GTSM)", RFC 5082, DOI 10.17487/RFC5082, October 2007, 527 . 529 [RFC6658] Bryant, S., Ed., Martini, L., Swallow, G., and A. Malis, 530 "Packet Pseudowire Encapsulation over an MPLS PSN", 531 RFC 6658, DOI 10.17487/RFC6658, July 2012, 532 . 534 [RFC8799] Carpenter, B. and B. Liu, "Limited Domains and Internet 535 Protocols", RFC 8799, DOI 10.17487/RFC8799, July 2020, 536 . 538 [I-D.schmutzer-bess-ple] 539 Gringeri, S., Whittaker, J., Leymann, N., Schmutzer, C., 540 Chiesa, L. D., Nainar, N. K., Pignataro, C., Smallegange, 541 G., Brown, C., and F. Dada, "Private Line Emulation over 542 Packet Switched Networks", Work in Progress, Internet- 543 Draft, draft-schmutzer-bess-ple-03, 17 August 2021, 544 . 547 Acknowledgments 549 TBA. 551 Authors' Addresses 553 Rakesh Gandhi 554 Cisco Systems, Inc. 555 Canada 557 Email: rgandhi@cisco.com 559 Patrice Brissette 560 Cisco Systems, Inc. 561 Canada 563 Email: pbrisset@cisco.com 565 Edward Leyton 566 Verizon Wireless 568 Email: edward.leyton@verizonwireless.com