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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 SPRING Working Group R. Gandhi, Ed. 3 Internet-Draft C. Filsfils 4 Intended status: Informational Cisco Systems, Inc. 5 Expires: December 7, 2020 D. Voyer 6 Bell Canada 7 M. Chen 8 Huawei 9 B. Janssens 10 Colt 11 June 5, 2020 13 Performance Measurement Using TWAMP Light for Segment Routing Networks 14 draft-gandhi-spring-twamp-srpm-09 16 Abstract 18 Segment Routing (SR) leverages the source routing paradigm. SR is 19 applicable to both Multiprotocol Label Switching (SR-MPLS) and IPv6 20 (SRv6) data planes. This document describes procedure for sending 21 and processing probe query and response messages for Performance 22 Measurement (PM) in Segment Routing networks. The procedure uses the 23 messages defined in RFC 5357 (Two-Way Active Measurement Protocol 24 (TWAMP) Light) for Delay Measurement, and uses the messages defined 25 in this document for Loss Measurement. The procedure described is 26 applicable to SR-MPLS and SRv6 data planes and is used for both Links 27 and end-to-end SR Paths including SR Policies. 29 Status of This Memo 31 This Internet-Draft is submitted in full conformance with the 32 provisions of BCP 78 and BCP 79. 34 Internet-Drafts are working documents of the Internet Engineering 35 Task Force (IETF). Note that other groups may also distribute 36 working documents as Internet-Drafts. The list of current Internet- 37 Drafts is at https://datatracker.ietf.org/drafts/current/. 39 Internet-Drafts are draft documents valid for a maximum of six months 40 and may be updated, replaced, or obsoleted by other documents at any 41 time. It is inappropriate to use Internet-Drafts as reference 42 material or to cite them other than as "work in progress." 44 This Internet-Draft will expire on December 7, 2020. 46 Copyright Notice 48 Copyright (c) 2020 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 (https://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 . . . . . . . . . . . . . . . . . . . . . . . . 3 64 2. Conventions Used in This Document . . . . . . . . . . . . . . 3 65 2.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 66 2.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 4 67 2.3. Reference Topology . . . . . . . . . . . . . . . . . . . 4 68 3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 5 69 3.1. Example Provisioning Model . . . . . . . . . . . . . . . 6 70 4. Probe Messages . . . . . . . . . . . . . . . . . . . . . . . 6 71 4.1. Probe Query Message . . . . . . . . . . . . . . . . . . . 7 72 4.1.1. Delay Measurement Query Message . . . . . . . . . . . 7 73 4.1.2. Loss Measurement Query Message . . . . . . . . . . . 8 74 4.1.3. Probe Query for Links . . . . . . . . . . . . . . . . 9 75 4.1.4. Probe Query for End-to-end Measurement for SR Policy 9 76 4.1.5. Control Code Field for TWAMP Light Messages . . . . . 10 77 4.1.6. Loss Measurement Query Message Formats . . . . . . . 11 78 4.2. Probe Response Message . . . . . . . . . . . . . . . . . 14 79 4.2.1. One-way Measurement Mode . . . . . . . . . . . . . . 15 80 4.2.2. Two-way Measurement Mode . . . . . . . . . . . . . . 15 81 4.2.3. Loss Measurement Response Message Formats . . . . . . 17 82 4.3. Additional Probe Message Processing Rules . . . . . . . . 19 83 4.3.1. TTL and Hop Limit . . . . . . . . . . . . . . . . . . 20 84 4.3.2. Router Alert Option . . . . . . . . . . . . . . . . . 20 85 4.3.3. UDP Checksum . . . . . . . . . . . . . . . . . . . . 20 86 5. Performance Measurement for P2MP SR Policies . . . . . . . . 20 87 6. ECMP Support for SR Policies . . . . . . . . . . . . . . . . 21 88 7. Performance Delay and Liveness Monitoring . . . . . . . . . . 21 89 8. Security Considerations . . . . . . . . . . . . . . . . . . . 22 90 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22 91 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 22 92 10.1. Normative References . . . . . . . . . . . . . . . . . . 22 93 10.2. Informative References . . . . . . . . . . . . . . . . . 23 95 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 26 96 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 26 98 1. Introduction 100 Segment Routing (SR) leverages the source routing paradigm and 101 greatly simplifies network operations for Software Defined Networks 102 (SDNs). SR is applicable to both Multiprotocol Label Switching (SR- 103 MPLS) and IPv6 (SRv6) data planes. SR takes advantage of the Equal- 104 Cost Multipaths (ECMPs) between source and transit nodes, between 105 transit nodes and between transit and destination nodes. SR Policies 106 as defined in [I-D.ietf-spring-segment-routing-policy] are used to 107 steer traffic through a specific, user-defined paths using a stack of 108 Segments. Built-in SR Performance Measurement (PM) is one of the 109 essential requirements to provide Service Level Agreements (SLAs). 111 The One-Way Active Measurement Protocol (OWAMP) defined in [RFC4656] 112 and Two-Way Active Measurement Protocol (TWAMP) defined in [RFC5357] 113 provide capabilities for the measurement of various performance 114 metrics in IP networks using probe messages. These protocols rely on 115 control-channel signaling to establish a test-channel over an UDP 116 path. The TWAMP Light [Appendix I in RFC5357] [BBF.TR-390] provides 117 simplified mechanisms for active performance measurement in Customer 118 IP networks by provisioning UDP paths and eliminates the need for 119 control-channel signaling. As described in Appendix A of [RFC8545], 120 TWAMP Light mechanism is informative only. These protocols lack 121 support for direct-mode Loss Measurement (LM) to detect actual 122 Customer data traffic loss which is required in SR networks. 124 This document describes procedures for sending and processing probe 125 query and response messages for Performance Measurement in SR 126 networks. The procedure uses the messages defined in [RFC5357] 127 (TWAMP Light) for Delay Measurement (DM), and uses the messages 128 defined in this document for Loss Measurement. The procedure 129 described is applicable to SR-MPLS and SRv6 data planes and is used 130 for both Links and end-to-end SR Paths including SR Policies. This 131 document also defines mechanisms for handling ECMPs of SR Paths for 132 performance delay measurement. Unless otherwise described, the 133 messages defined in [RFC5357] are not modified by this document. 135 2. Conventions Used in This Document 137 2.1. Requirements Language 139 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 140 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 141 document are to be interpreted as described in [RFC2119] [RFC8174] 142 when, and only when, they appear in all capitals, as shown here. 144 2.2. Abbreviations 146 BSID: Binding Segment ID. 148 DM: Delay Measurement. 150 ECMP: Equal Cost Multi-Path. 152 HMAC: Hashed Message Authentication Code. 154 LM: Loss Measurement. 156 MPLS: Multiprotocol Label Switching. 158 NTP: Network Time Protocol. 160 OWAMP: One-Way Active Measurement Protocol. 162 PM: Performance Measurement. 164 PSID: Path Segment Identifier. 166 PTP: Precision Time Protocol. 168 SID: Segment ID. 170 SL: Segment List. 172 SR: Segment Routing. 174 SRH: Segment Routing Header. 176 SR-MPLS: Segment Routing with MPLS data plane. 178 SRv6: Segment Routing with IPv6 data plane. 180 TC: Traffic Class. 182 TWAMP: Two-Way Active Measurement Protocol. 184 2.3. Reference Topology 186 In the reference topology shown below, the sender node R1 initiates a 187 probe query for performance measurement and the reflector node R5 188 sends a probe response for the query message received. The probe 189 response is sent to the sender node R1. The nodes R1 and R5 may be 190 directly connected via a Link or there exists a Point-to-Point (P2P) 191 SR Paths e.g. SR Policy [I-D.ietf-spring-segment-routing-policy] on 192 node R1 with destination to node R5. In case of Point-to-Multipoint 193 (P2MP), SR Policy originating from source node R1 may terminate on 194 multiple destination leaf nodes 195 [I-D.voyer-spring-sr-replication-segment]. 197 +-------+ t1 Query t2 +-------+ 198 | | - - - - - - - - - ->| | 199 | R1 |=====================| R5 | 200 | |<- - - - - - - - - - | | 201 +-------+ t4 Response t3 +-------+ 202 Sender Reflector 204 Reference Topology 206 3. Overview 208 For one-way and two-way delay measurements in Segment Routing 209 networks, the probe messages defined in [RFC5357] are used. For 210 direct-mode and inferred-mode loss measurements in Segment Routing 211 networks, the messages defined in this document are used. Separate 212 UDP destination port numbers are user-configured for delay and loss 213 measurements. As specified in [RFC8545], the reflector supports the 214 destination UDP port 862 for delay measurement probe messages by 215 default. This UDP port however, is not used for loss measurement 216 probe messages defined in this document. The sender uses the UDP 217 port number following the guidelines specified in Section 6 in 218 [RFC6335]. For both Links and end-to-end SR Paths including SR 219 Policies, no PM session for delay or loss measurement is created on 220 the reflector node R5 [RFC5357]. 222 For Performance Measurement, probe query and response messages are 223 sent as following: 225 o For Delay Measurement, the probe messages are sent on the 226 congruent path of the data traffic by the sender node, and are 227 used to measure the delay experienced by the actual data traffic 228 flowing on the Links and SR Policies. 230 o For Loss Measurement, the probe messages are sent on the congruent 231 path of the data traffic by the sender node, and are used to 232 collect the receive traffic counters for the incoming link or 233 incoming SID where the probe query messages are received at the 234 reflector node (incoming link or incoming SID needed since the 235 reflector node does not have PM session state present). 237 The In-Situ Operations, Administration, and Maintenance (IOAM) 238 mechanisms for SR-MPLS defined in [I-D.gandhi-mpls-ioam-sr] and for 239 SRv6 defined in [I-D.ali-spring-ioam-srv6] are used to carry PM 240 information such as timestamp in-band as part of the data packets, 241 and are outside the scope of this document. 243 3.1. Example Provisioning Model 245 An example of a provisioning model and typical measurement parameters 246 for each user-configured destination UDP port for performance delay 247 and loss measurements is shown in the following Figure 1: 249 +------------+ 250 | Controller | 251 +------------+ 252 Destination UDP Port / \ Destination UDP port 253 Measurement Protocol / \ Measurement Protocol 254 Measurement Type / \ Measurement Type 255 Delay/Loss / \ Delay/Loss 256 Authentication Mode & Key / \ Authentication Mode & Key 257 Timestamp Format / \ Loss Measurement Mode 258 Delay Measurement Mode / \ 259 Loss Measurement Mode / \ 260 v v 261 +-------+ +-------+ 262 | | | | 263 | R1 |============| R5 | 264 | | SR Path | | 265 +-------+ Or Link +-------+ 266 Sender Reflector 268 Figure 1: Example Provisioning Model 270 Example of Measurement Protocol is TWAMP Light, example of the 271 Timestamp Format is PTPv2 [IEEE1588] or NTP and example of the Loss 272 Measurement mode is inferred-mode or direct-mode. 274 The mechanisms to provision the sender and reflector nodes are 275 outside the scope of this document. 277 The reflector node R5 uses the parameters for the timestamp format 278 and delay measurement mode (i.e. one-way or two-way mode) from the 279 received probe query message. 281 4. Probe Messages 282 4.1. Probe Query Message 284 The probe messages defined in [RFC5357] are used for Delay 285 Measurement for Links and end-to-end SR Paths including SR Policies. 286 For Loss Measurement, the probe messages defined in this document are 287 used. 289 The Sender IPv4 or IPv6 address is used as the source address. The 290 reflector IPv4 or IPv6 address is used as the destination address. 291 In the case of SR Policy with IPv4 endpoint of 0.0.0.0 or IPv6 292 endpoint of ::0 [I-D.ietf-spring-segment-routing-policy], the address 293 in the range of 127/8 for IPv4 or ::FFFF:127/104 for IPv6 is used as 294 the destination address, respectively. 296 4.1.1. Delay Measurement Query Message 298 The message content for Delay Measurement probe query message using 299 UDP header [RFC0768] is shown in Figure 2. The DM probe query 300 message is sent with user-configured Destination UDP port number for 301 DM. The Destination UDP port cannot be used as Source port for DM, 302 since the message does not have any indication to distinguish between 303 the query and response message. The payload of the DM probe query 304 message contains the delay measurement message defined in 305 Section 4.1.2 of [RFC5357]. For symmetrical size query and response 306 messages as defined in [RFC6038], the DM probe query message contains 307 the payload format defined in Section 4.2.1 of [RFC5357]. 309 +---------------------------------------------------------------+ 310 | IP Header | 311 . Source IP Address = Sender IPv4 or IPv6 Address . 312 . Destination IP Address = Reflector IPv4 or IPv6 Address . 313 . Protocol = UDP . 314 . . 315 +---------------------------------------------------------------+ 316 | UDP Header | 317 . Source Port = As chosen by Sender . 318 . Destination Port = User-configured Port for Delay Measurement. 319 . . 320 +---------------------------------------------------------------+ 321 | Payload = DM Message as specified in Section 4.2.1 of RFC 5357| 322 . Payload = DM Message as specified in Section 4.1.2 of RFC 5357. 323 . . 324 +---------------------------------------------------------------+ 326 Figure 2: DM Probe Query Message 328 Timestamp field is eight bytes and use the format defined in 329 Section 4.2.1 of [RFC5357]. It is recommended to use the IEEE 1588v2 330 Precision Time Protocol (PTP) truncated 64-bit timestamp format 331 [IEEE1588] as specified in [RFC8186], with hardware support in 332 Segment Routing networks. 334 4.1.1.1. Delay Measurement Authentication Mode 336 When using the authenticated mode for delay measurement, the matching 337 authentication type (e.g. HMAC-SHA-256) and key are user-configured 338 on both the sender and reflector nodes. A separate user-configured 339 destination UDP port is used for the delay measurement in 340 authentication mode due to the different probe message format. 342 4.1.2. Loss Measurement Query Message 344 The message content for Loss Measurement probe query message using 345 UDP header [RFC0768] is shown in Figure 3. The LM probe query 346 message is sent with user-configured Destination UDP port number for 347 LM, which is a different Destination UDP port number than DM. 348 Separate Destination UDP ports are used for direct-mode and inferred- 349 mode loss measurements. The Destination UDP port cannot be used as 350 Source port for LM, since the message does not have any indication to 351 distinguish between the query and response message. The LM probe 352 query message contains the payload for loss measurement as defined in 353 Figure 7 and Figure 8. 355 +---------------------------------------------------------------+ 356 | IP Header | 357 . Source IP Address = Sender IPv4 or IPv6 Address . 358 . Destination IP Address = Reflector IPv4 or IPv6 Address . 359 . Protocol = UDP . 360 . . 361 +---------------------------------------------------------------+ 362 | UDP Header | 363 . Source Port = As chosen by Sender . 364 . Destination Port = User-configured Port for Loss Measurement . 365 . . 366 +---------------------------------------------------------------+ 367 | Payload = LM Message as specified in Figure 7 or 8 | 368 . . 369 +---------------------------------------------------------------+ 371 Figure 3: LM Probe Query Message 373 4.1.2.1. Loss Measurement Authentication Mode 375 When using the authenticated mode for loss measurement, the matching 376 authentication type (e.g. HMAC-SHA-256) and key are user-configured 377 on both the sender and reflector nodes. A separate user-configured 378 destination UDP port is used for the loss measurement in 379 authentication mode due to the different message format. 381 4.1.3. Probe Query for Links 383 The probe query message as defined in Figure 2 for delay measurement 384 and Figure 3 for loss measurement is sent on the congruent path of 385 the data traffic. The probe messages are routed over the Link for 386 both delay and loss measurement. 388 4.1.4. Probe Query for End-to-end Measurement for SR Policy 390 The performance delay and loss measurement for segment routing is 391 applicable to both SR-MPLS and SRv6 Policies. 393 4.1.4.1. Probe Query Message for SR-MPLS Policy 395 The probe query messages for end-to-end performance measurement of an 396 SR-MPLS Policy is sent using its SR-MPLS header containing the MPLS 397 segment list as shown in Figure 4. 399 0 1 2 3 400 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 1 401 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 402 | Segment(1) | TC |S| TTL | 403 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 404 . . 405 . . 406 . . 407 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 408 | Segment(n) | TC |S| TTL | 409 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 410 | PSID | TC |S| TTL | 411 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 412 | Message as shown in Figure 2 for DM or Figure 3 for LM | 413 . . 414 +---------------------------------------------------------------+ 416 Figure 4: Example Probe Query Message for SR-MPLS Policy 418 The Segment List (SL) can be empty to indicate Implicit NULL label 419 case for a single-hop SR Policy. 421 The Path Segment Identifier (PSID) 422 [I-D.ietf-spring-mpls-path-segment] of the SR-MPLS Policy is used for 423 accounting received traffic on the egress node for loss measurement. 425 4.1.4.2. Probe Query Message for SRv6 Policy 427 An SRv6 Policy setup using the SRv6 Segment Routing Header (SRH) and 428 a Segment List as defined in [RFC8754]. For SRv6, network 429 programming is defined in [I-D.ietf-spring-srv6-network-programming]. 430 The probe query messages for end-to-end performance measurement of an 431 SRv6 Policy is sent using its SRH with Segment List as shown in 432 Figure 5. 434 +---------------------------------------------------------------+ 435 | IP Header | 436 . Source IP Address = Sender IPv6 Address . 437 . Destination IP Address = Destination IPv6 Address . 438 . . 439 +---------------------------------------------------------------+ 440 | SRH as specified in RFC 8754 | 441 . . 442 . . 443 +---------------------------------------------------------------+ 444 | IP Header (Optional) | 445 . Source IP Address = Sender IPv6 Address . 446 . Destination IP Address = Reflector IPv6 Address . 447 . . 448 +---------------------------------------------------------------+ 449 | UDP Header | 450 . Source Port = As chosen by Sender . 451 . Destination Port = User-configured Port . 452 . . 453 +---------------------------------------------------------------+ 454 | Payload = DM Message as specified in Section 4.2.1 of RFC 5357| 455 . Payload = DM Message as specified in Section 4.1.2 of RFC 5357. 456 . Payload = LM Message as specified in Figure 7 or 8 . 457 . . 458 +---------------------------------------------------------------+ 460 Figure 5: Example Probe Query Message for SRv6 Policy 462 4.1.5. Control Code Field for TWAMP Light Messages 464 The Control Code field is defined for delay and loss measurement 465 probe query messages for TWAMP Light in unauthenticated and 466 authenticated modes. The modified delay measurement probe query 467 message format is shown in Figure 6. This message format is 468 backwards compatible with the message format defined in [RFC5357] as 469 its reflectors ignore the received field (previously identified as 470 MBZ). The usage of the Control Code is not limited to the SR paths 471 and can be used for non-SR paths in a network. 473 . . 474 . . 475 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 476 | Timestamp | 477 | | 478 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 479 | Error Estimate | MBZ | 480 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 481 | MBZ |Se Control Code| 482 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 483 . . 484 . . 486 Figure 6: Sender Control Code in TWAMP Light DM Message 488 Sender Control Code: Set as follows in TWAMP Light probe query 489 message. 491 In a Query: 493 0x0: Out-of-band Response Requested. Indicates that the probe 494 response is not required over the same path in the reverse 495 direction. This is also the default behavior. 497 0x1: In-band Response Requested. Indicates that this query has 498 been sent over a bidirectional path and the probe response is 499 required over the same path in the reverse direction. 501 0x2: No Response Requested. 503 4.1.6. Loss Measurement Query Message Formats 505 In this document, TWAMP Light probe query messages for loss 506 measurement are defined as shown in Figure 7 and Figure 8. The 507 message formats are hardware efficient due to well-known locations of 508 the counters and payload small in size. They are stand-alone and 509 similar to the delay measurement message formats (e.g. location of 510 the Counter and Timestamp). They also do not require backwards 511 compatibility and support for the existing DM message formats from 512 [RFC5357] as different user-configured destination UDP port is used 513 for loss measurement. 515 0 1 2 3 516 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 1 517 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 518 | Sequence Number | 519 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 520 | Transmit Counter | 521 | | 522 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 523 |X|B| Reserved | Block Number | MBZ | 524 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 525 | MBZ |Se Control Code| 526 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 527 | | 528 . . 529 . Packet Padding . 530 . . 531 | | 532 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 534 Figure 7: TWAMP Light LM Probe Query Message - Unauthenticated Mode 535 0 1 2 3 536 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 1 537 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 538 | Sequence Number | 539 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 540 | MBZ (12 octets) | 541 | | 542 | | 543 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 544 | Transmit Counter | 545 | | 546 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 547 |X|B| Reserved | Block Number | MBZ | 548 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 549 | MBZ |Se Control Code| 550 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 551 | HMAC (16 octets) | 552 | | 553 | | 554 | | 555 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 556 | | 557 . . 558 . Packet Padding . 559 . . 560 | | 561 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 563 Figure 8: TWAMP Light LM Probe Query Message - Authenticated Mode 565 Sequence Number (32-bit): As defined in [RFC5357]. 567 Transmit Counter (64-bit): The number of packets or octets sent by 568 the sender node in the query message and by the reflector node in the 569 response message. The counter is always written at the well-known 570 location in the probe query and response messages. 572 Receive Counter (64-bit): The number of packets or octets received at 573 the reflector node. It is written by the reflector node in the probe 574 response message. 576 Sender Counter (64-bit): This is the exact copy of the transmit 577 counter from the received query message. It is written by the 578 reflector node in the probe response message. 580 Sender Sequence Number (32-bit): As defined in [RFC5357]. 582 Sender TTL: As defined in Section 7.1. 584 LM Flags: The meanings of the Flag bits are: 586 X: Extended counter format indicator. Indicates the use of 587 extended (64-bit) counter values. Initialized to 1 upon creation 588 (and prior to transmission) of an LM Query and copied from an LM 589 Query to an LM response. Set to 0 when the LM message is 590 transmitted or received over an interface that writes 32-bit 591 counter values. 593 B: Octet (byte) count. When set to 1, indicates that the Counter 594 1-4 fields represent octet counts. The octet count applies to all 595 packets within the LM scope, and the octet count of a packet sent 596 or received includes the total length of that packet (but excludes 597 headers, labels, or framing of the channel itself). When set to 598 0, indicates that the Counter fields represent packet counts. 600 Block Number (8-bit): The Loss Measurement using Alternate-Marking 601 method defined in [RFC8321] requires to color the data traffic. To 602 be able to compare the transmit and receive traffic counters of the 603 matching color, the Block Number (or color) of the traffic counters 604 is carried by the probe query and response messages for loss 605 measurement. 607 HMAC: The PM probe message in authenticated mode includes a key 608 Hashed Message Authentication Code (HMAC) [RFC2104] hash. Each probe 609 query and response messages are authenticated by adding Sequence 610 Number with Hashed Message Authentication Code (HMAC) TLV. It can 611 use HMAC-SHA-256 truncated to 128 bits (similarly to the use of it in 612 IPSec defined in [RFC4868]); hence the length of the HMAC field is 16 613 octets. 615 HMAC uses its own key and the mechanism to distribute the HMAC key is 616 outside the scope of this document. 618 In authenticated mode, only the sequence number is encrypted, and the 619 other payload fields are sent in clear text. The probe message may 620 include Comp.MBZ (Must Be Zero) variable length field to align the 621 packet on 16 octets boundary. 623 4.2. Probe Response Message 625 The probe response message is sent using the IP/UDP information from 626 the received probe query message. The content of the probe response 627 message is shown in Figure 9. 629 +---------------------------------------------------------------+ 630 | IP Header | 631 . Source IP Address = Reflector IPv4 or IPv6 Address . 632 . Destination IP Address = Source IP Address from Query . 633 . Protocol = UDP . 634 . . 635 +---------------------------------------------------------------+ 636 | UDP Header | 637 . Source Port = As chosen by Reflector . 638 . Destination Port = Source Port from Query . 639 . . 640 +---------------------------------------------------------------+ 641 | Payload = DM Message as specified in Section 4.2.1 of RFC 5357| 642 . Payload = LM Message as specified in Figure 12 or 13 . 643 . . 644 +---------------------------------------------------------------+ 646 Figure 9: Probe Response Message 648 4.2.1. One-way Measurement Mode 650 In one-way performance measurement mode, the probe response message 651 as defined in Figure 9 is sent back out-of-band to the sender node, 652 for both Links and SR Policies. The Sender Control Code is set to 653 "Out-of-band Response Requested". In this delay measurement mode, as 654 per Reference Topology, all timestamps t1, t2, t3, and t4 are 655 collected by the probes. However, only timestamps t1 and t2 are used 656 to measure one-way delay. 658 4.2.2. Two-way Measurement Mode 660 In two-way performance measurement mode, when using a bidirectional 661 path, the probe response message as defined in Figure 9 is sent back 662 to the sender node on the congruent path of the data traffic on the 663 same reverse direction Link or associated reverse SR Policy 664 [I-D.ietf-pce-sr-bidir-path]. The Sender Control Code is set to "In- 665 band Response Requested". In this delay measurement mode, as per 666 Reference Topology, all timestamps t1, t2, t3, and t4 are collected 667 by the probes. All four timestamps are used to measure two-way 668 delay. 670 Specifically, the probe response message is sent back on the incoming 671 physical interface where the probe query message is received. This 672 is required for example, in case of two-way measurement mode for Link 673 delay. 675 4.2.2.1. Probe Response Message for SR-MPLS Policy 677 The message content for sending probe response message for two-way 678 end-to-end performance measurement of an SR-MPLS Policy is shown in 679 Figure 10. 681 0 1 2 3 682 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 1 683 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 684 | Segment(1) | TC |S| TTL | 685 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 686 . . 687 . . 688 . . 689 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 690 | Segment(n) | TC |S| TTL | 691 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 692 | Message as shown in Figure 9 | 693 . . 694 +---------------------------------------------------------------+ 696 Figure 10: Example Probe Response Message for SR-MPLS Policy 698 The Path Segment Identifier (PSID) 699 [I-D.ietf-spring-mpls-path-segment] of the forward SR Policy in the 700 probe query can be used to find the associated reverse SR Policy 701 [I-D.ietf-pce-sr-bidir-path] to send the probe response message for 702 two-way measurement of SR Policy. 704 4.2.2.2. Probe Response Message for SRv6 Policy 706 The message content for sending probe response message on the 707 congruent path of the data traffic for two-way end-to-end performance 708 measurement of an SRv6 Policy with SRH is shown in Figure 11. 710 +---------------------------------------------------------------+ 711 | IP Header | 712 . Source IP Address = Reflector IPv6 Address . 713 . Destination IP Address = Destination IPv6 Address . 714 . . 715 +---------------------------------------------------------------+ 716 | SRH as specified in RFC 8754 | 717 . . 718 . . 719 +---------------------------------------------------------------+ 720 | IP Header (Optional) | 721 . Source IP Address = Reflector IPv6 Address . 722 . Destination IP Address = Source IPv6 Address from Query . 723 . . 724 +---------------------------------------------------------------+ 725 | UDP Header | 726 . Source Port = As chosen by Sender . 727 . Destination Port = User-configured Port . 728 . . 729 +---------------------------------------------------------------+ 730 | Payload = DM Message as specified in Section 4.2.1 of RFC 5357| 731 . Payload = LM Message as specified in Figure 12 or 13 . 732 . . 733 +---------------------------------------------------------------+ 735 Figure 11: Example Probe Response Message for SRv6 Policy 737 4.2.3. Loss Measurement Response Message Formats 739 In this document, TWAMP Light probe response message formats are 740 defined for loss measurement as shown in Figure 12 and Figure 13. 742 0 1 2 3 743 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 1 744 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 745 | Sequence Number | 746 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 747 | Transmit Counter | 748 | | 749 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 750 |X|B| Reserved | Block Number | MBZ | 751 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 752 | Receive Counter | 753 | | 754 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 755 | Sender Sequence Number | 756 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 757 | Sender Counter | 758 | | 759 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 760 |X|B| Reserved |Sender Block Nu| MBZ | 761 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 762 | Sender TTL | | 763 +-+-+-+-+-+-+-+-+ + 764 | | 765 . . 766 . Packet Padding . 767 . . 768 | | 769 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 771 Figure 12: TWAMP Light LM Probe Response Message - Unauthenticated 772 Mode 774 0 1 2 3 775 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 1 776 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 777 | Sequence Number | 778 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 779 | MBZ (12 octets) | 780 | | 781 | | 782 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 783 | Transmit Counter | 784 | | 785 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 786 |X|B| Reserved | Block Number | MBZ | 787 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 788 | MBZ (4 octets) | 789 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 790 | Receive Counter | 791 | | 792 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 793 | MBZ (8 octets) | 794 | | 795 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 796 | Sender Sequence Number | 797 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 798 | MBZ (12 octets) | 799 | | 800 | | 801 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 802 | Sender Counter | 803 | | 804 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 805 |X|B| Reserved |Sender Block Nu| MBZ | 806 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 807 | MBZ (4 octets) | 808 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 809 | Sender TTL | | 810 +-+-+-+-+-+-+-+-+ | 811 | MBZ (15 octets) | 812 | | 813 | | 814 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 815 | HMAC (16 octets) | 816 | | 817 | | 818 | | 819 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 820 | | 821 . . 822 . Packet Padding . 823 . . 824 | | 825 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 827 Figure 13: TWAMP Light LM Probe Response Message - Authenticated Mode 829 4.3. Additional Probe Message Processing Rules 831 The processing rules defined in this section are applicable to TWAMP 832 Light messages for delay and loss measurement for Links and end-to- 833 end SR Paths including SR Policies. 835 4.3.1. TTL and Hop Limit 837 The TTL field in the IPv4 and MPLS headers of the probe query 838 messages is set to 255 [RFC5357]. Similarly, the Hop Limit field in 839 the IPv6 and SRH headers of the probe query messages is set to 255 840 [RFC5357]. 842 When using the Destination IPv4 Address from the 127/8 range, the TTL 843 field in the IPv4 header is set to 1 [RFC8029]. Similarly, when 844 using the Destination IPv6 Address from the ::FFFF:127/104 range, the 845 Hop Limit field in the IPv6 header is set to 1. 847 For Link performance delay and loss measurements, the TTL or Hop 848 Limit field in the probe message is set to 1 in both one-way and two- 849 way measurement modes. 851 4.3.2. Router Alert Option 853 The Router Alert IP option (RAO) [RFC2113] is not set in the probe 854 messages. 856 4.3.3. UDP Checksum 858 The UDP Checksum Complement for delay and loss measurement messages 859 follows the procedure defined in [RFC7820] and can be optionally used 860 with the procedures defined in this document. 862 For IPv4 and IPv6 probe messages, where the hardware is not capable 863 of re-computing the UDP checksum or adding checksum complement 864 [RFC7820], the sender node sets the UDP checksum to 0 [RFC6936] 865 [RFC8085]. The receiving node bypasses the checksum validation and 866 accepts the packets with UDP checksum value 0 for the UDP port being 867 used for PM delay and loss measurements. 869 5. Performance Measurement for P2MP SR Policies 871 The procedures for delay and loss measurement described in this 872 document for Point-to-Point (P2P) SR Policies 873 [I-D.ietf-spring-segment-routing-policy] are also equally applicable 874 to the Point-to-Multipoint (P2MP) SR Policies as following: 876 o The sender root node sends probe query messages using the 877 Replication Segment defined in 878 [I-D.voyer-spring-sr-replication-segment] for the P2MP SR Policy 879 as shown in Figure 14. 881 o Each reflector leaf node sends its IP address in the Source 882 Address of the probe response messages as shown in Figure 9. This 883 allows the sender root node to identify the reflector leaf nodes 884 of the P2MP SR Policy. 886 o The P2MP root node measures the end-to-end delay and loss 887 performance for each P2MP leaf node of the P2MP SR Policy. 889 0 1 2 3 890 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 1 891 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 892 | Replication SID | TC |S| TTL | 893 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 894 | Message as shown in Figure 2 for DM or Figure 3 for LM | 895 . . 896 +---------------------------------------------------------------+ 898 Figure 14: Example Query with Replication Segment for SR-MPLS Policy 900 6. ECMP Support for SR Policies 902 An SR Policy can have ECMPs between the source and transit nodes, 903 between transit nodes and between transit and destination nodes. 904 Usage of Anycast SID [RFC8402] by an SR Policy can result in ECMP 905 paths via transit nodes part of that Anycast group. The PM probe 906 messages need to be sent to traverse different ECMP paths to measure 907 performance delay of an SR Policy. 909 Forwarding plane has various hashing functions available to forward 910 packets on specific ECMP paths. The mechanisms described in 911 [RFC8029] and [RFC5884] for handling ECMPs are also applicable to the 912 performance measurement. In IPv4 header of the PM probe messages, 913 sweeping of Destination Address in 127/8 range can be used to 914 exercise particular ECMP paths. As specified in [RFC6437], Flow 915 Label field in the outer IPv6 header can also be used for sweeping. 917 The considerations for performance loss measurement for different 918 ECMP paths of an SR Policy are outside the scope of this document. 920 7. Performance Delay and Liveness Monitoring 922 The procedure defined in this document for delay measurement using 923 the TWAMP Light probe messages can also be applied to liveness 924 monitoring of Links and SR Paths. The one-way or two-way measurement 925 mode can be used for liveness monitoring. Liveness failure is 926 notified when consecutive N number of probe response messages are not 927 received back at the sender node, where N is locally provisioned 928 value. Note that detection interval and scale for number of sessions 929 need to account for the processing of the probe messages which are 930 punted out of fast path in forwarding (to slow path or control 931 plane), and re-injected back on the reflector node. 933 8. Security Considerations 935 The performance measurement is intended for deployment in well- 936 managed private and service provider networks. As such, it assumes 937 that a node involved in a measurement operation has previously 938 verified the integrity of the path and the identity of the far-end 939 reflector node. 941 If desired, attacks can be mitigated by performing basic validation 942 and sanity checks, at the sender, of the counter or timestamp fields 943 in received measurement response messages. The minimal state 944 associated with these protocols also limits the extent of measurement 945 disruption that can be caused by a corrupt or invalid message to a 946 single query/response cycle. 948 Use of HMAC-SHA-256 in the authenticated mode protects the data 949 integrity of the probe messages. SRv6 has HMAC protection 950 authentication defined for SRH [RFC8754]. Hence, PM probe messages 951 for SRv6 may not need authentication mode. Cryptographic measures 952 may be enhanced by the correct configuration of access-control lists 953 and firewalls. 955 9. IANA Considerations 957 This document does not require any IANA action. 959 10. References 961 10.1. Normative References 963 [RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768, 964 DOI 10.17487/RFC0768, August 1980, 965 . 967 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 968 Requirement Levels", BCP 14, RFC 2119, 969 DOI 10.17487/RFC2119, March 1997, 970 . 972 [RFC4656] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M. 973 Zekauskas, "A One-way Active Measurement Protocol 974 (OWAMP)", RFC 4656, DOI 10.17487/RFC4656, September 2006, 975 . 977 [RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J. 978 Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)", 979 RFC 5357, DOI 10.17487/RFC5357, October 2008, 980 . 982 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 983 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 984 May 2017, . 986 10.2. Informative References 988 [IEEE1588] 989 IEEE, "1588-2008 IEEE Standard for a Precision Clock 990 Synchronization Protocol for Networked Measurement and 991 Control Systems", March 2008. 993 [RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed- 994 Hashing for Message Authentication", RFC 2104, 995 DOI 10.17487/RFC2104, February 1997, 996 . 998 [RFC2113] Katz, D., "IP Router Alert Option", RFC 2113, 999 DOI 10.17487/RFC2113, February 1997, 1000 . 1002 [RFC4868] Kelly, S. and S. Frankel, "Using HMAC-SHA-256, HMAC-SHA- 1003 384, and HMAC-SHA-512 with IPsec", RFC 4868, 1004 DOI 10.17487/RFC4868, May 2007, 1005 . 1007 [RFC5884] Aggarwal, R., Kompella, K., Nadeau, T., and G. Swallow, 1008 "Bidirectional Forwarding Detection (BFD) for MPLS Label 1009 Switched Paths (LSPs)", RFC 5884, DOI 10.17487/RFC5884, 1010 June 2010, . 1012 [RFC6038] Morton, A. and L. Ciavattone, "Two-Way Active Measurement 1013 Protocol (TWAMP) Reflect Octets and Symmetrical Size 1014 Features", RFC 6038, DOI 10.17487/RFC6038, October 2010, 1015 . 1017 [RFC6335] Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S. 1018 Cheshire, "Internet Assigned Numbers Authority (IANA) 1019 Procedures for the Management of the Service Name and 1020 Transport Protocol Port Number Registry", BCP 165, 1021 RFC 6335, DOI 10.17487/RFC6335, August 2011, 1022 . 1024 [RFC6437] Amante, S., Carpenter, B., Jiang, S., and J. Rajahalme, 1025 "IPv6 Flow Label Specification", RFC 6437, 1026 DOI 10.17487/RFC6437, November 2011, 1027 . 1029 [RFC6936] Fairhurst, G. and M. Westerlund, "Applicability Statement 1030 for the Use of IPv6 UDP Datagrams with Zero Checksums", 1031 RFC 6936, DOI 10.17487/RFC6936, April 2013, 1032 . 1034 [RFC7820] Mizrahi, T., "UDP Checksum Complement in the One-Way 1035 Active Measurement Protocol (OWAMP) and Two-Way Active 1036 Measurement Protocol (TWAMP)", RFC 7820, 1037 DOI 10.17487/RFC7820, March 2016, 1038 . 1040 [RFC8029] Kompella, K., Swallow, G., Pignataro, C., Ed., Kumar, N., 1041 Aldrin, S., and M. Chen, "Detecting Multiprotocol Label 1042 Switched (MPLS) Data-Plane Failures", RFC 8029, 1043 DOI 10.17487/RFC8029, March 2017, 1044 . 1046 [RFC8085] Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage 1047 Guidelines", BCP 145, RFC 8085, DOI 10.17487/RFC8085, 1048 March 2017, . 1050 [RFC8186] Mirsky, G. and I. Meilik, "Support of the IEEE 1588 1051 Timestamp Format in a Two-Way Active Measurement Protocol 1052 (TWAMP)", RFC 8186, DOI 10.17487/RFC8186, June 2017, 1053 . 1055 [RFC8321] Fioccola, G., Ed., Capello, A., Cociglio, M., Castaldelli, 1056 L., Chen, M., Zheng, L., Mirsky, G., and T. Mizrahi, 1057 "Alternate-Marking Method for Passive and Hybrid 1058 Performance Monitoring", RFC 8321, DOI 10.17487/RFC8321, 1059 January 2018, . 1061 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., 1062 Decraene, B., Litkowski, S., and R. Shakir, "Segment 1063 Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, 1064 July 2018, . 1066 [RFC8545] Morton, A., Ed. and G. Mirsky, Ed., "Well-Known Port 1067 Assignments for the One-Way Active Measurement Protocol 1068 (OWAMP) and the Two-Way Active Measurement Protocol 1069 (TWAMP)", RFC 8545, DOI 10.17487/RFC8545, March 2019, 1070 . 1072 [RFC8754] Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J., 1073 Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header 1074 (SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020, 1075 . 1077 [I-D.ietf-spring-segment-routing-policy] 1078 Filsfils, C., Sivabalan, S., Voyer, D., Bogdanov, A., and 1079 P. Mattes, "Segment Routing Policy Architecture", draft- 1080 ietf-spring-segment-routing-policy-07 (work in progress), 1081 May 2020. 1083 [I-D.voyer-spring-sr-replication-segment] 1084 Voyer, D., Filsfils, C., Parekh, R., Bidgoli, H., and Z. 1085 Zhang, "SR Replication Segment for Multi-point Service 1086 Delivery", draft-voyer-spring-sr-replication-segment-03 1087 (work in progress), June 2020. 1089 [I-D.ietf-spring-mpls-path-segment] 1090 Cheng, W., Li, H., Chen, M., Gandhi, R., and R. Zigler, 1091 "Path Segment in MPLS Based Segment Routing Network", 1092 draft-ietf-spring-mpls-path-segment-02 (work in progress), 1093 February 2020. 1095 [I-D.ietf-spring-srv6-network-programming] 1096 Filsfils, C., Camarillo, P., Leddy, J., Voyer, D., 1097 Matsushima, S., and Z. Li, "SRv6 Network Programming", 1098 draft-ietf-spring-srv6-network-programming-15 (work in 1099 progress), March 2020. 1101 [BBF.TR-390] 1102 "Performance Measurement from IP Edge to Customer 1103 Equipment using TWAMP Light", BBF TR-390, May 2017. 1105 [I-D.gandhi-mpls-ioam-sr] 1106 Gandhi, R., Ali, Z., Filsfils, C., Brockners, F., Wen, B., 1107 and V. Kozak, "MPLS Data Plane Encapsulation for In-situ 1108 OAM Data", draft-gandhi-mpls-ioam-sr-02 (work in 1109 progress), March 2020. 1111 [I-D.ali-spring-ioam-srv6] 1112 Ali, Z., Gandhi, R., Filsfils, C., Brockners, F., Kumar, 1113 N., Pignataro, C., Li, C., Chen, M., and G. Dawra, 1114 "Segment Routing Header encapsulation for In-situ OAM 1115 Data", draft-ali-spring-ioam-srv6-02 (work in progress), 1116 November 2019. 1118 [I-D.ietf-pce-sr-bidir-path] 1119 Li, C., Chen, M., Cheng, W., Gandhi, R., and Q. Xiong, 1120 "PCEP Extensions for Associated Bidirectional Segment 1121 Routing (SR) Paths", draft-ietf-pce-sr-bidir-path-02 (work 1122 in progress), March 2020. 1124 Acknowledgments 1126 The authors would like to thank Thierry Couture for the discussions 1127 on the use-cases for Performance Measurement in Segment Routing. The 1128 authors would also like to thank Greg Mirsky for reviewing this 1129 document and providing useful comments and suggestions. Patrick 1130 Khordoc and Radu Valceanu, both from Cisco Systems have helped 1131 significantly improve the mechanisms defined in this document. The 1132 authors would like to acknowledge the earlier work on the loss 1133 measurement using TWAMP described in draft-xiao-ippm-twamp-ext- 1134 direct-loss. 1136 Authors' Addresses 1138 Rakesh Gandhi (editor) 1139 Cisco Systems, Inc. 1140 Canada 1142 Email: rgandhi@cisco.com 1144 Clarence Filsfils 1145 Cisco Systems, Inc. 1147 Email: cfilsfil@cisco.com 1149 Daniel Voyer 1150 Bell Canada 1152 Email: daniel.voyer@bell.ca 1154 Mach(Guoyi) Chen 1155 Huawei 1157 Email: mach.chen@huawei.com 1158 Bart Janssens 1159 Colt 1161 Email: Bart.Janssens@colt.net