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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) -- Obsolete informational reference (is this intentional?): RFC 8321 (Obsoleted by RFC 9341) Summary: 0 errors (**), 0 flaws (~~), 1 warning (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 MPLS Working Group R. Gandhi, Ed. 3 Internet-Draft C. Filsfils 4 Intended Status: Standards Track Cisco Systems, Inc. 5 Expires: June 6, 2020 D. Voyer 6 Bell Canada 7 S. Salsano 8 Universita di Roma "Tor Vergata" 9 M. Chen 10 Huawei 11 December 4, 2019 13 Performance Measurement for 14 Segment Routing Networks with MPLS Data Plane 15 draft-gandhi-mpls-rfc6374-sr-01 17 Abstract 19 Segment Routing (SR) leverages the source routing paradigm. RFC 6374 20 specifies protocol mechanisms to enable the efficient and accurate 21 measurement of packet loss, one-way and two-way delay, as well as 22 related metrics such as delay variation in MPLS networks using probe 23 messages. This document utilizes these mechanisms for Performance 24 Delay and Loss Measurements in Segment Routing (SR) networks with 25 MPLS data plane (SR-MPLS), for both SR links and end-to-end SR 26 Policies. In addition, this document defines Return Path TLV for 27 two-way performance measurement and Block Number TLV for loss 28 measurement. 30 Status of This Memo 32 This Internet-Draft is submitted in full conformance with the 33 provisions of BCP 78 and BCP 79. 35 Internet-Drafts are working documents of the Internet Engineering 36 Task Force (IETF). Note that other groups may also distribute 37 working documents as Internet-Drafts. The list of current Internet- 38 Drafts is at http://datatracker.ietf.org/drafts/current/. 40 Internet-Drafts are draft documents valid for a maximum of six months 41 and may be updated, replaced, or obsoleted by other documents at any 42 time. It is inappropriate to use Internet-Drafts as reference 43 material or to cite them other than as "work in progress." 45 Copyright Notice 46 Copyright (c) 2019 IETF Trust and the persons identified as the 47 document authors. All rights reserved. 49 This document is subject to BCP 78 and the IETF Trust's Legal 50 Provisions Relating to IETF Documents 51 (http://trustee.ietf.org/license-info) in effect on the date of 52 publication of this document. Please review these documents 53 carefully, as they describe your rights and restrictions with respect 54 to this document. Code Components extracted from this document must 55 include Simplified BSD License text as described in Section 4.e of 56 the Trust Legal Provisions and are provided without warranty as 57 described in the Simplified BSD License. 59 Table of Contents 61 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 62 2. Conventions Used in This Document . . . . . . . . . . . . . . 4 63 2.1. Requirements Language . . . . . . . . . . . . . . . . . . 4 64 2.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 4 65 2.3. Reference Topology . . . . . . . . . . . . . . . . . . . . 5 66 3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 67 4. Probe Query and Response Packets . . . . . . . . . . . . . . . 6 68 4.1. Probe Packet Header for SR-MPLS Policies . . . . . . . . . 6 69 4.2. Probe Packet Header for SR-MPLS Links . . . . . . . . . . 7 70 4.3. Probe Response Message for SR-MPLS Links and Policies . . 7 71 4.3.1. One-way Measurement Mode . . . . . . . . . . . . . . . 7 72 4.3.2. Two-way Measurement Mode . . . . . . . . . . . . . . . 7 73 4.3.3. Loopback Measurement Mode . . . . . . . . . . . . . . 8 74 4.4. Return Path TLV . . . . . . . . . . . . . . . . . . . . . 8 75 5. Performance Delay Measurement . . . . . . . . . . . . . . . . 9 76 5.1. Delay Measurement Message Format . . . . . . . . . . . . . 9 77 5.2. Timestamps . . . . . . . . . . . . . . . . . . . . . . . . 10 78 6. Performance Loss Measurement . . . . . . . . . . . . . . . . . 10 79 6.1. Loss Measurement Message Format . . . . . . . . . . . . . 11 80 6.2. Block Number TLV . . . . . . . . . . . . . . . . . . . . . 11 81 7. Performance Measurement for P2MP SR Policies . . . . . . . . . 11 82 8. ECMP for SR-MPLS Policies . . . . . . . . . . . . . . . . . . 12 83 9. SR Link Extended TE Metrics Advertisements . . . . . . . . . . 13 84 10. Security Considerations . . . . . . . . . . . . . . . . . . . 13 85 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 86 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 87 12.1. Normative References . . . . . . . . . . . . . . . . . . 14 88 12.2. Informative References . . . . . . . . . . . . . . . . . 14 89 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 17 90 Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 91 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17 93 1. Introduction 95 Service provider's ability to satisfy Service Level Agreements (SLAs) 96 depend on the ability to measure and monitor performance metrics for 97 packet loss and one-way and two-way delay, as well as related metrics 98 such as delay variation. The ability to monitor these performance 99 metrics also provides operators with greater visibility into the 100 performance characteristics of their networks, thereby facilitating 101 planning, troubleshooting, and network performance evaluation. 103 Segment Routing (SR) leverages the source routing paradigm and 104 greatly simplifies network operations for Software Defined Networks 105 (SDNs). SR is applicable to both Multiprotocol Label Switching 106 (SR-MPLS) and IPv6 (SRv6) data planes. SR takes advantage of the 107 Equal-Cost Multipaths (ECMPs) between source and transit nodes, 108 between transit nodes and between transit and destination nodes. SR 109 Policies as defined in [I-D.spring-segment-routing-policy] are used 110 to steer traffic through a specific, user-defined paths using a stack 111 of Segments. Built-in SR Performance Measurement (PM) is one of the 112 essential requirements to provide Service Level Agreements (SLAs). 114 [RFC6374] specifies protocol mechanisms to enable the efficient and 115 accurate measurement of performance metrics in MPLS networks using 116 probe messages. The One-Way Active Measurement Protocol (OWAMP) 117 defined in [RFC4656] and Two-Way Active Measurement Protocol (TWAMP) 118 defined in [RFC5357] provide capabilities for the measurement of 119 various performance metrics in IP networks. However, mechanisms 120 defined in [RFC6374] are more suitable for Segment Routing (SR) when 121 using MPLS data plane (SR-MPLS). [RFC6374] also supports IEEE 1588 122 timestamps [IEEE1588] and "direct mode" Loss Measurement (LM), which 123 are required in SR networks. 125 [RFC7876] specifies the procedures to be used when sending and 126 processing out-of-band performance measurement probe replies over an 127 UDP return path when receiving RFC 6374 based probe queries. These 128 procedures can be used to send out-of-band PM replies for both 129 SR-MPLS links and Policies [I-D.spring-segment-routing-policy] for 130 one-way measurement. 132 This document utilizes the probe-based mechanisms defined in 133 [RFC6374] for Performance Delay and Loss Measurements in SR networks 134 with MPLS data plane, for both SR links and end-to-end SR Policies. 135 In addition, this document defines Return Path TLV for two-way 136 performance measurement and Block Number TLV for loss measurement. 137 The Performance Measurements (PM) for SR links are used to compute 138 extended Traffic Engineering (TE) metrics for delay and loss and can 139 be advertised in the network using the routing protocol extensions. 141 2. Conventions Used in This Document 143 2.1. Requirements Language 145 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 146 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 147 document are to be interpreted as described in [RFC2119] [RFC8174] 148 when, and only when, they appear in all capitals, as shown here. 150 2.2. Abbreviations 152 ACH: Associated Channel Header. 154 DM: Delay Measurement. 156 ECMP: Equal Cost Multi-Path. 158 G-ACh: Generic Associated Channel (G-ACh). 160 GAL: Generic Associated Channel (G-ACh) Label. 162 LM: Loss Measurement. 164 MPLS: Multiprotocol Label Switching. 166 NTP: Network Time Protocol. 168 PM: Performance Measurement. 170 PSID: Path Segment Identifier. 172 PTP: Precision Time Protocol. 174 SID: Segment ID. 176 SL: Segment List. 178 SR: Segment Routing. 180 SR-MPLS: Segment Routing with MPLS data plane. 182 TC: Traffic Class. 184 TE: Traffic Engineering. 186 URO: UDP Return Object. 188 2.3. Reference Topology 190 In the reference topology shown in Figure 1, the sender node R1 191 initiates a performance measurement probe query and the responder 192 node R5 sends a probe response for the query message received. The 193 probe response is typically sent back to the sender node R1. The 194 nodes R1 and R5 may be directly connected via a link enabled with 195 Segment Routing or there exists a Point-to-Point (P2P) SR Policy 196 [I-D.spring-segment-routing-policy] on node R1 with destination to 197 node R5. In case of Point-to-Multipoint (P2MP), SR Policy 198 originating from source node R1 may terminate on multiple destination 199 leaf nodes [I-D.spring-sr-p2mp-policy]. 201 +-------+ Query +-------+ 202 | | - - - - - - - - - ->| | 203 | R1 |---------------------| R5 | 204 | |<- - - - - - - - - - | | 205 +-------+ Response +-------+ 206 Sender Responder 208 Figure 1: Reference Topology 210 3. Overview 212 One-way delay and two-way delay measurement procedure defined in 213 Section 2.4 of [RFC6374] are used. Transmit and Receive packet loss 214 measurement procedures defined in Section 2.2 and Section 2.6 of 215 [RFC6374] are used. One-way loss measurement provides receive packet 216 loss whereas two-way loss measurement provides both transmit and 217 receive packet loss. For both links and end-to-end SR Policies, no 218 PM session for delay or loss measurement is created on the responder 219 node R5 [RFC6374]. 221 For Performance Measurement, probe query and response messages are 222 sent as following: 224 o For Delay Measurement, the probe messages are sent on the 225 congruent path of the data traffic by the sender node, and are 226 used to measure the delay experienced by the actual data traffic 227 flowing on the links and SR Policies. 229 o For Loss Measurement, the probe messages are sent on the congruent 230 path of the data traffic by the sender node, and are used to 231 collect the receive traffic counters for the incoming link or 232 incoming SID where the probe query messages are received at the 233 responder node (incoming link or incoming SID needed since the 234 responder node does not have PM session state present). 236 o For SR Policy performance measurement, in order to ensure that the 237 probe query message is processed by the intended responder node, 238 destination address TLV [RFC6374] can be sent in the probe query 239 message. The responder node only replies if it is the intended 240 destination for the probe query. 242 The In-Situ Operations, Administration, and Maintenance (IOAM) 243 mechanisms for SR-MPLS defined in [I-D.mpls-ioam-sr] are used to 244 carry PM information in-band as part of the data traffic packets, and 245 are outside the scope of this document. 247 4. Probe Query and Response Packets 249 4.1. Probe Packet Header for SR-MPLS Policies 251 As described in Section 2.9.1 of [RFC6374], MPLS PM probe query and 252 response messages flow over the MPLS Generic Associated Channel 253 (G-ACh). A probe packet for an end-to-end measurement for SR Policy 254 contains SR-MPLS label stack [I-D.spring-segment-routing-policy], 255 with the G-ACh Label (GAL) at the bottom of the stack (with S=1). 256 The GAL is followed by an Associated Channel Header (ACH), which 257 identifies the message type, and the message payload following the 258 ACH as shown in Figure 2. 260 0 1 2 3 261 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 1 262 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 263 | Label(1) | TC |S| TTL | 264 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 265 . . 266 . . 267 . . 268 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 269 | Label(n) | TC |S| TTL | 270 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 271 | GAL (value 13) | TC |S| TTL | 272 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 273 |0 0 0 1|Version| Reserved | GAL Channel Type | 274 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 276 Figure 2: Probe Packet Header for an End-to-end SR-MPLS Policy 278 The SR-MPLS label stack can be empty (as shown in Figure 3) to 279 indicate Implicit NULL label case. 281 4.2. Probe Packet Header for SR-MPLS Links 283 As described in Section 2.9.1 of [RFC6374], MPLS PM probe query and 284 response messages flow over the MPLS Generic Associated Channel 285 (G-ACh). A probe packet for SR-MPLS links contains G-ACh Label (GAL) 286 (with S=1). The GAL is followed by an Associated Channel Header 287 (ACH), which identifies the message type, and the message payload 288 following the ACH as shown in Figure 3. 290 0 1 2 3 291 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 1 292 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 293 | GAL (value 13) | TC |S| TTL | 294 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 295 |0 0 0 1|Version| Reserved | GAL Channel Type | 296 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 298 Figure 3: Probe Packet Header for an SR-MPLS Link 300 4.3. Probe Response Message for SR-MPLS Links and Policies 302 4.3.1. One-way Measurement Mode 304 In one-way performance measurement mode [RFC7679], the PM sender node 305 can receive "out-of-band" probe replies by properly setting the UDP 306 Return Object (URO) TLV in the probe query message. The URO TLV 307 (Type=131) is defined in [RFC7876] and includes the 308 UDP-Destination-Port and IP Address. In particular, if the sender 309 sets its own IP address in the URO TLV, the probe response is sent 310 back by the responder node to the sender node. In addition, the 311 "control code" in the probe query message is set to "out-of-band 312 response requested". 314 4.3.2. Two-way Measurement Mode 316 In two-way performance measurement mode [RFC6374], when using a 317 bidirectional path, the probe response message is sent back to the 318 sender node on the congruent path of the data traffic on the reverse 319 direction SR Link or associated SR Policy [I-D.bidir-sr] using a 320 message with format similar to their probe query message. In this 321 case, the "control code" in the probe query message is set to "in- 322 band response requested". 324 A Path Segment Identifier (PSID) [I-D.spring-mpls-path-segment] of 325 the forward SR-MPLS Policy can be used to find the associated reverse 326 SR-MPLS Policy [I-D.bidir-sr] and to send back the probe response 327 message for two-way measurement. 329 4.3.3. Loopback Measurement Mode 331 The Loopback measurement mode defined in Section 2.8 of [RFC6374] can 332 be used to measure round-trip delay for a bidirectional SR Path 333 [I-D.bidir-sr]. The probe query messages in this case carries the 334 reverse SR Path label stack as part of the MPLS header. The GAL is 335 still carried at the bottom of the label stack (with S=1). The 336 responder node does not process the PM probe messages and generate 337 response messages. 339 4.4. Return Path TLV 341 For two-way performance measurement, the responder node needs to send 342 the probe response message on a specific reverse path. The sender 343 node can request in the probe query message to the responder node to 344 send a response message back on a given reverse path (e.g. co-routed 345 path for two-way measurement). This way the destination node does 346 not require any additional SR Policy state. 348 For one-way performance measurement, the sender node address may not 349 be reachable via IP route from the responder node. The sender node 350 in this case needs to send its reachability path information to the 351 responder node. 353 [RFC6374] defines DM and LM probe query messages that can include one 354 or more optional TLVs. New TLV Type (TBA1) is defined in this 355 document for Return Path to carry reverse path for probe response 356 messages (in the payload of the message). The format of the Return 357 Path TLV is shown in Figure 4A and 4B: 359 0 1 2 3 360 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 1 361 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 362 | Type = TBA1 | Length | Reserved | 363 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 364 | Return Path Sub-TLVs | 365 . . 366 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 368 Figure 4A: Return Path TLV 370 0 1 2 3 371 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 1 372 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 373 | Type | Length | Reserved | 374 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 375 | Label(1) | 376 . . 377 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 378 . . 379 . . 380 . . 381 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 382 | Label(n) | 383 . . 384 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 386 Figure 4B: Segment List Sub-TLV in Return Path TLV 388 The Segment List Sub-TLV in the Return Path TLV can be one of the 389 following Types: 391 o Type (value 1): SR-MPLS Label Stack of the Reverse SR Path 393 o Type (value 2): SR-MPLS Binding SID [I-D.pce-binding-label-sid] of 394 the Reverse SR Policy 396 The Return Path TLV is optional. The PM sender node MUST only insert 397 one Return Path TLV in the probe query message and the responder node 398 MUST only process the first Return Path TLV in the probe query 399 message and ignore other Return Path TLVs if present. The responder 400 node MUST send probe response message back on the reverse path 401 specified in the Return Path TLV and MUST NOT add Return Path TLV in 402 the probe response message. In the absence of Return Path TLV, in 403 two-way measurement mode, the probe response message is sent back on 404 the incoming physical interface where the probe query message is 405 received. 407 5. Performance Delay Measurement 409 5.1. Delay Measurement Message Format 411 As defined in [RFC6374], MPLS DM probe query and response messages 412 use Associated Channel Header (ACH) (value 0x000C for delay 413 measurement) [RFC6374], which identifies the message type, and the 414 message payload following the ACH. For both SR links and end-to-end 415 measurement for SR-MPLS Policies, the same MPLS DM ACH value is used. 417 The DM message payload as defined in Section 3.2 of [RFC6374] is used 418 for SR-MPLS delay measurement, for both SR links and end-to-end SR 419 Policies. 421 5.2. Timestamps 423 The Section 3.4 of [RFC6374] defines timestamp format that can be 424 used for delay measurement. The IEEE 1588 Precision Time Protocol 425 (PTP) timestamp format [IEEE1588] is used by default as described in 426 Appendix A of [RFC6374], preferred with hardware support in Segment 427 Routing networks. 429 Note that for one-way delay measurement mode, clock synchronization 430 between the sender and responder nodes is required. The two-way 431 delay measurement mode and loopback measurement mode do not require 432 clock synchronization between the sender and responder nodes. 434 6. Performance Loss Measurement 436 The LM protocol can perform two distinct kinds of loss measurement as 437 described in Section 2.9.8 of [RFC6374]. 439 o In inferred mode, LM will measure the loss of specially generated 440 test messages in order to infer the approximate data plane loss 441 level. Inferred mode LM provides only approximate loss 442 accounting. 444 o In direct mode, LM will directly measure data plane packet loss. 445 Direct mode LM provides perfect loss accounting, but may require 446 hardware support. 448 For both of these modes of LM, Path Segment Identifier (PSID) 449 [I-D.spring-mpls-path-segment] is used for accounting received 450 traffic on the egress node of the SR-MPLS Policy as shown in Figure 451 5. Different values of PSID can be used to measure packet loss per 452 SR-MPLS Policy, per Candidate Path or per Segment List of the SR 453 Policy. 455 0 1 2 3 456 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 1 457 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 458 | PSID | TC |S| TTL | 459 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 460 | GAL (value 13) | TC |S| TTL | 461 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 462 |0 0 0 1|Version| Reserved | GAL Channel Type | 463 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 465 Figure 5: With Path Segment Identifier for SR-MPLS Policy 467 6.1. Loss Measurement Message Format 469 As defined in [RFC6374], MPLS LM probe query and response messages 470 use Associated Channel Header (ACH) (value 0x000A for direct loss 471 measurement or value 0x000B for inferred loss measurement), which 472 identifies the message type, and the message payload following the 473 ACH. For both SR links and end-to-end measurement for SR-MPLS 474 Policies, the same MPLS LM ACH value is used. 476 The LM message payload as defined in Section 3.1 of [RFC6374] is used 477 for SR-MPLS loss measurement, for both SR links and end-to-end SR 478 Policies. 480 6.2. Block Number TLV 482 The Loss Measurement using Alternate-Marking method defined in 483 [RFC8321] requires to color the data traffic. To be able to compare 484 the transmit and receive traffic counters of the matching color, the 485 Block Number (or color) of the traffic counters is carried by the 486 probe query and response messages for loss measurement. Probe query 487 and response messages specified in [RFC6374] for Loss Measurement do 488 not identify the Block Number of the counters. 490 [RFC6374] defines probe query and response messages that can include 491 one or more optional TLVs. New TLV Type (value TBA2) is defined in 492 this document to carry the Block Number (8-bit) of the traffic 493 counters in the probe query and response messages for loss 494 measurement. The format of the Block Number TLV is shown in Figure 495 6: 497 0 1 2 3 498 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 1 499 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 500 | Type TBA2 | Length | Reserved | Block Number | 501 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 503 Figure 6: Block Number TLV 505 The Block Number TLV is optional. The PM sender node SHOULD only 506 insert one Block Number TLV in the probe query message and the 507 responder node in the probe response message SHOULD return the first 508 Block Number TLV from the probe query messages and ignore other Block 509 Number TLVs if present. In probe messages, the counters MUST belong 510 to the same Block Number. 512 7. Performance Measurement for P2MP SR Policies 513 The procedures for delay and loss measurement described in this 514 document for Point-to-Point (P2P) SR-MPLS Policies 515 [I-D.spring-segment-routing-policy] are also equally applicable to 516 the Point-to-Multipoint (P2MP) SR-MPLS Policies 517 [I-D.spring-sr-p2mp-policy] as following: 519 o The sender root node sends probe query messages using the 520 Replication Segment defined in [I-D.spring-sr-p2mp-policy] for the 521 P2MP SR Policy as shown in Figure 7. 523 o Each responder leaf node adds the "Source Address" TLV (Type 130) 524 [RFC6374] with its IP address in the probe response messages. 525 This TLV allows the sender root node to identify the responder 526 leaf nodes of the P2MP SR Policy. 528 o The P2MP root node measures the end-to-end delay and loss 529 performance for each P2MP leaf node of the P2MP SR Policy. 531 0 1 2 3 532 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 1 533 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 534 | Replication SID | TC |S| TTL | 535 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 536 | GAL (value 13) | TC |S| TTL | 537 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 538 |0 0 0 1|Version| Reserved | GAL Channel Type | 539 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 541 Figure 7: With Replication Segment for SR-MPLS Policy 543 8. ECMP for SR-MPLS Policies 545 An SR Policy can have ECMPs between the source and transit nodes, 546 between transit nodes and between transit and destination nodes. 547 Usage of Anycast SID [RFC8402] by an SR Policy can result in ECMP 548 paths via transit nodes part of that Anycast group. The PM probe 549 messages need to be sent to traverse different ECMP paths to measure 550 performance delay of each of the ECMP path of an SR Policy. 552 Forwarding plane has various hashing functions available to forward 553 packets on specific ECMP paths. For SR-MPLS Policy, sweeping of 554 entropy label [RFC6790] values can be used in PM probe messages to 555 take advantage of the hashing function in forwarding plane to 556 influence the ECMP path taken by them. 558 The considerations for performance loss measurement for different 559 ECMP paths of an SR Policy are outside the scope of this document. 561 9. SR Link Extended TE Metrics Advertisements 563 The extended TE metrics for SR link delay and loss computed using the 564 performance measurement procedures described in this document can be 565 advertised in the routing domain as follows: 567 o For OSPF, ISIS, and BGP-LS, protocol extensions defined in 568 [RFC7471], [RFC8570], and [RFC8571] are used, respectively for 569 advertising the extended TE link metrics in the network. 571 o The advertised delay-variance metric is computed as specified in 572 Section 4.2 of [RFC5481]. 574 o The extended TE link one-way delay metrics can be computed using 575 two-way delay measurement or round-trip delay measurement from 576 loopback mode by dividing the measured delay values by 2. 578 o The extended TE link delay and loss metrics are advertised for 579 Layer 2 bundle members in OSPF [I-D.lsr-ospf-l2bundles] and ISIS 580 [I-D.isis-l2bundles] using the same mechanisms defined in 581 [RFC7471] and [RFC8570], respectively. 583 10. Security Considerations 585 This document describes the procedures for performance delay and loss 586 measurement for SR-MPLS networks, for both links and end-to-end SR 587 Policies using the mechanisms defined in [RFC6374] and [RFC7876]. 588 This document does not introduce any additional security 589 considerations other than those covered in [RFC6374], [RFC7471], 590 [RFC8570], [RFC8571], and [RFC7876]. 592 11. IANA Considerations 594 IANA is requested to allocate a value for the following optional 595 Return Path TLV Type for RFC 6374 to be carried in PM probe query 596 messages: 598 o Type TBA1: Return Path TLV 600 IANA is requested to allocate the values for the following Sub-TLV 601 Types for the Return Path TLV for RFC 6374. 603 o Type (value 1): SR-MPLS Label Stack of the Reverse SR Path 605 o Type (value 2): SR-MPLS Binding SID [I-D.pce-binding-label-sid] of 606 the Reverse SR Policy 608 IANA is also requested to allocate a value for the following optional 609 Block Number TLV Type for RFC 6374 to be carried in the PM probe 610 query and response messages for loss measurement: 612 o Type TBA2: Block Number TLV 614 12. References 616 12.1. Normative References 618 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 619 Requirement Levels", RFC 2119, March 1997. 621 [RFC6374] Frost, D. and S. Bryant, "Packet Loss and Delay 622 Measurement for MPLS networks', RFC 6374, September 2011. 624 [RFC7876] Bryant, S., Sivabalan, S., and Soni, S., "UDP Return Path 625 for Packet Loss and Delay Measurement for MPLS Networks", 626 RFC 7876, July 2016. 628 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 629 2119 Key Words", RFC 8174, May 2017. 631 12.2. Informative References 633 [IEEE1588] IEEE, "1588-2008 IEEE Standard for a Precision Clock 634 Synchronization Protocol for Networked Measurement and 635 Control Systems", March 2008. 637 [RFC4656] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M. 638 Zekauskas, "A One-way Active Measurement Protocol 639 (OWAMP)", RFC 4656, September 2006. 641 [RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J. 642 Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)", 643 RFC 5357, October 2008. 645 [RFC5481] Morton, A. and B. Claise, "Packet Delay Variation 646 Applicability Statement", RFC 5481, March 2009. 648 [RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and 649 L. Yong, "The Use of Entropy Labels in MPLS Forwarding", 650 RFC 6790, November 2012. 652 [RFC7679] Almes, G., et al., "A One-Way Delay Metric for IP 653 Performance Metrics (IPPM)', RFC 7679, January 2016. 655 [RFC7471] Giacalone, S., et al., "OSPF Traffic Engineering (TE) 656 Metric Extensions", RFC 7471, March 2015. 658 [RFC8321] Fioccola, G. Ed., "Alternate-Marking Method for Passive 659 and Hybrid Performance Monitoring", RFC 8321, January 660 2018. 662 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., 663 Decraene, B., Litkowski, S., and R. Shakir, "Segment 664 Routing Architecture", RFC 8402, July 2018. 666 [RFC8570] Ginsberg, L. Ed., et al., "IS-IS Traffic Engineering (TE) 667 Metric Extensions", RFC 8570, March 2019. 669 [RFC8571] Ginsberg, L. Ed., et al., "BGP - Link State (BGP-LS) 670 Advertisement of IGP Traffic Engineering Performance 671 Metric Extensions", RFC 8571, March 2019. 673 [I-D.spring-segment-routing-policy] Filsfils, C., et al., "Segment 674 Routing Policy Architecture", 675 draft-ietf-spring-segment-routing-policy, work in 676 progress. 678 [I-D.spring-sr-p2mp-policy] Voyer, D. Ed., et al., "SR Replication 679 Segment for Multi-point Service Delivery", 680 draft-voyer-spring-sr-replication-segment, work in 681 progress. 683 [I-D.pce-binding-label-sid] Filsfils, C., et al., "Carrying Binding 684 Label/Segment-ID in PCE-based Networks", 685 draft-ietf-pce-binding-label-sid, work in progress. 687 [I-D.spring-mpls-path-segment] Cheng, W., et al., "Path Segment in 688 MPLS Based Segment Routing Network", 689 draft-ietf-spring-mpls-path-segment, work in progress. 691 [I-D.mpls-ioam-sr] Gandhi, R. Ed., et al., "Segment Routing with 692 MPLS Data Plane Encapsulation for In-situ OAM Data", 693 draft-gandhi-mpls-ioam-sr, work in progress. 695 [I-D.lsr-ospf-l2bundles] Talaulikar, K., et al., "Advertising L2 696 Bundle Member Link Attributes in OSPF", 697 draft-ketant-lsr-ospf-l2bundles, work in progress. 699 [I-D.isis-l2bundles] Ginsberg, L., et al., "Advertising L2 Bundle 700 Member Link Attributes in IS-IS", 701 draft-ietf-isis-l2bundles, work in progress. 703 [I-D.bidir-sr] Li, C., et al., "PCEP Extensions for Associated 704 Bidirectional Segment Routing (SR) Paths", 705 draft-li-pce-sr-bidir-path, work in progress. 707 Acknowledgments 709 The authors would like to thank Thierry Couture for the discussions 710 on the use-cases for the performance measurement in segment routing 711 networks. The authors would like to thank Greg Mirsky for providing 712 many useful comments and suggestions. The authors would also like to 713 thank Stewart Bryant, Sam Aldrin, Tarek Saad, and Rajiv Asati for 714 their review comments. 716 Contributors 718 Sagar Soni 719 Cisco Systems, Inc. 720 Email: sagsoni@cisco.com 722 Patrick Khordoc 723 Cisco Systems, Inc. 724 Email: pkhordoc@cisco.com 726 Zafar Ali 727 Cisco Systems, Inc. 728 Email: zali@cisco.com 730 Pier Luigi Ventre 731 CNIT 732 Italy 733 Email: pierluigi.ventre@cnit.it 735 Authors' Addresses 737 Rakesh Gandhi (editor) 738 Cisco Systems, Inc. 739 Canada 740 Email: rgandhi@cisco.com 742 Clarence Filsfils 743 Cisco Systems, Inc. 744 Email: cfilsfil@cisco.com 746 Daniel Voyer 747 Bell Canada 748 Email: daniel.voyer@bell.ca 750 Stefano Salsano 751 Universita di Roma "Tor Vergata" 752 Italy 753 Email: stefano.salsano@uniroma2.it 755 Mach(Guoyi) Chen 756 Huawei 757 Email: mach.chen@huawei.com