idnits 2.17.1 draft-ietf-mpls-rfc6374-sfl-00.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (June 12, 2017) is 2481 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-09) exists of draft-bryant-mpls-sfl-control-01 == Outdated reference: A later version (-05) exists of draft-bryant-mpls-sfl-framework-04 == Outdated reference: A later version (-14) exists of draft-ietf-ippm-alt-mark-04 == Outdated reference: A later version (-07) exists of draft-ietf-mpls-flow-ident-04 Summary: 0 errors (**), 0 flaws (~~), 5 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 MPLS Working Group S. Bryant 3 Internet-Draft M. Chen 4 Intended status: Standards Track Z. Li 5 Expires: December 14, 2017 Huawei 6 G. Swallow 7 S. Sivabalan 8 Cisco Systems 9 G. Mirsky 10 ZTE Corp. 11 G. Fioccola 12 Telecom Italia 13 June 12, 2017 15 RFC6374 Synonymous Flow Labels 16 draft-ietf-mpls-rfc6374-sfl-00 18 Abstract 20 This document describes a method of making RFC6374 performance 21 measurements on flows carried over an MPLS Label Switched path. This 22 allows loss and delay measurements to be made on multi-point to point 23 LSPs and allows the measurement of flows within an MPLS construct 24 using RFC6374. 26 Status of This Memo 28 This Internet-Draft is submitted in full conformance with the 29 provisions of BCP 78 and BCP 79. 31 Internet-Drafts are working documents of the Internet Engineering 32 Task Force (IETF). Note that other groups may also distribute 33 working documents as Internet-Drafts. The list of current Internet- 34 Drafts is at http://datatracker.ietf.org/drafts/current/. 36 Internet-Drafts are draft documents valid for a maximum of six months 37 and may be updated, replaced, or obsoleted by other documents at any 38 time. It is inappropriate to use Internet-Drafts as reference 39 material or to cite them other than as "work in progress." 41 This Internet-Draft will expire on December 14, 2017. 43 Copyright Notice 45 Copyright (c) 2017 IETF Trust and the persons identified as the 46 document authors. All rights reserved. 48 This document is subject to BCP 78 and the IETF Trust's Legal 49 Provisions Relating to IETF Documents 50 (http://trustee.ietf.org/license-info) in effect on the date of 51 publication of this document. Please review these documents 52 carefully, as they describe your rights and restrictions with respect 53 to this document. Code Components extracted from this document must 54 include Simplified BSD License text as described in Section 4.e of 55 the Trust Legal Provisions and are provided without warranty as 56 described in the Simplified BSD License. 58 Table of Contents 60 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 61 2. Requirements Language . . . . . . . . . . . . . . . . . . . . 4 62 3. RFC6374 Packet Loss Measurement with SFL . . . . . . . . . . 4 63 4. RFC6374 Single Packet Delay Measurement . . . . . . . . . . . 4 64 5. Data Service Packet Delay Measurement . . . . . . . . . . . . 4 65 6. Some Simplifying Rules . . . . . . . . . . . . . . . . . . . 6 66 7. Multiple Packet Delay Characteristics . . . . . . . . . . . . 6 67 7.1. Method 1: Time Buckets . . . . . . . . . . . . . . . . . 7 68 7.2. Method 2 Classic Standard Deviation . . . . . . . . . . . 9 69 7.2.1. RFC6374 Multi-Packet Delay Measurement Message Format 10 70 7.3. Per Packet Delay Measurement . . . . . . . . . . . . . . 11 71 7.4. Average Delay . . . . . . . . . . . . . . . . . . . . . . 11 72 8. Sampled Measurement . . . . . . . . . . . . . . . . . . . . . 13 73 9. Carrying RFC6374 Packets over an LSP using an SFL . . . . . . 13 74 9.1. RFC6374 SFL TLV . . . . . . . . . . . . . . . . . . . . . 15 75 10. Applicability to Pro-active and On-demand Measurement . . . . 16 76 11. RFC6374 Combined Loss-Delay Measurement . . . . . . . . . . . 16 77 12. Privacy Considerations . . . . . . . . . . . . . . . . . . . 16 78 13. Security Considerations . . . . . . . . . . . . . . . . . . . 17 79 14. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 80 14.1. Allocation of PW Associated Channel Type . . . . . . . . 17 81 14.2. MPLS Loss/Delay TLV Object . . . . . . . . . . . . . . . 17 82 15. References . . . . . . . . . . . . . . . . . . . . . . . . . 17 83 15.1. Normative References . . . . . . . . . . . . . . . . . . 17 84 15.2. Informative References . . . . . . . . . . . . . . . . . 18 85 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19 87 1. Introduction 89 [RFC6374] was originally designed for use as an OAM protocol for use 90 with MPLS Transport Profile (MPLS-TP) [RFC5921] LSPs. MPLS-TP only 91 supports point-to-point and point-to-multi-point LSPs. This document 92 describes how to use RFC6374 in the general MPLS case, and also 93 introduces a number of more sophisticated measurements of 94 applicability to both cases. 96 [I-D.ietf-mpls-flow-ident] describes the requirement for introducing 97 flow identities when using RFC6374 [RFC6374] packet Loss Measurements 98 (LM). In summary RFC6374 uses the loss-measurement (LM) packet as 99 the packet accounting demarcation point. Unfortunately this gives 100 rise to a number of problems that may lead to significant packet 101 accounting errors in certain situations. For example: 103 1. Where a flow is subjected to Equal Cost Multi-Path (ECMP) 104 treatment packets can arrive out of order with respect to the LM 105 packet. 107 2. Where a flow is subjected to ECMP treatment, packets can arrive 108 at different hardware interfaces, thus requiring reception of an 109 LM packet on one interface to trigger a packet accounting action 110 on a different interface which may not be co-located with it. 111 This is a difficult technical problem to address with the 112 required degree of accuracy. 114 3. Even where there is no ECMP (for example on RSVP-TE, MPLS-TP LSPs 115 and PWs) local processing may be distributed over a number of 116 processor cores, leading to synchronization problems. 118 4. Link aggregation techniques may also lead to synchronization 119 issues. 121 5. Some forwarder implementations have a long pipeline between 122 processing a packet and incrementing the associated counter again 123 leading to synchronization difficulties. 125 An approach to mitigating these synchronization issue is described in 126 [I-D.tempia-ippm-p3m] and 127 [I-D.chen-ippm-coloring-based-ipfpm-framework] in which packets are 128 batched by the sender and each batch is marked in some way such that 129 adjacent batches can be easily recognized by the receiver. 131 An additional problem arises where the LSP is a multi-point to point 132 LSP, since MPLS does not include a source address in the packet. 133 Network management operations require the measurement of packet loss 134 between a source and destination. It is thus necessary to introduce 135 some source specific information into the packet to identify packet 136 batches from a specific source. 138 [I-D.bryant-mpls-sfl-framework] describes a method of encoding per 139 flow instructions in an MPLS label stack using a technique called 140 Synonymous Flow Labels (SFL) in which labels which mimic the 141 behaviour of other labels provide the packet batch identifiers and 142 enable the per batch packet accounting. This memo specifies how SFLs 143 are used to perform RFC6374 packet loss and RFC6374 delay 144 measurements. 146 2. Requirements Language 148 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 149 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 150 "OPTIONAL" in this document are to be interpreted as described in 151 [RFC2119]. 153 3. RFC6374 Packet Loss Measurement with SFL 155 The data service packets of the flow being instrumented are grouped 156 into batches, and all the packets within a batch are marked with the 157 SFL [I-D.ietf-mpls-flow-ident] corresponding to that batch. The 158 sender counts the number of packets in the batch. When the batch has 159 completed and the sender is confident that all of the packets in that 160 batch will have been received, the sender issues an RFC6374 Query 161 message to determine the number actually received and hence the 162 number of packets lost. The RFC6374 Query message is sent using the 163 same SFL as the co-responding batch of data service packets. The 164 format of the Query and Response packet is described in Section 9. 166 4. RFC6374 Single Packet Delay Measurement 168 RFC6374 describes how to measure the packet delay by measuring the 169 transit time of an RFC6374 packet over an LSP. Such a packet may not 170 need to be carried over an SFL since the delay over a particular LSP 171 should be a function of the TC bits. 173 However where SFLs are being used to monitor packet loss or where 174 label inferred scheduling is used [RFC3270] then the SFL would be 175 REQUIRED to ensure that the RFC6374 packet which was being used as a 176 proxy for a data service packet experienced a representative delay. 177 The format of an RFC6374 packet carried over the LSP using an SFL is 178 shown in Section 9. 180 5. Data Service Packet Delay Measurement 182 Where it is desired to more thoroughly instrument a packet flow and 183 to determine the delay of a number of packets it is undesirable to 184 send a large number of RFC6374 packets acting as proxy data service 185 packets Section 4. A method of directly measuring the delay 186 characteristics of a batch of packets is therefore needed. 188 Given the long intervals over which it is necessary to measure packet 189 loss, it is not necessarily the case that the batch times for the two 190 measurement types would be identical. This it is proposed that the 191 two measurements are relatively independent. The notion that they 192 are relatively independent arises for the potential for the two 193 batches to overlap in time, in which case either the delay batch time 194 will need to be cut short or the loss time will need to be extended 195 to allow correct reconciliation of the various counters. 197 The problem is illustrated in Figure 1 below: 199 (1) AAAAAAAAAABBBBBBBBBBAAAAAAAAAABBBBBBBBBB 201 SFL Marking of a packet batch for loss measurement 203 (2) AADDDDAAAABBBBBBBBBBAAAAAAAAAABBBBBBBBBB 205 SFL Marking of a subset if the packets for delay 207 (3) AAAAAAAADDDDBBBBBBBBAAAAAAAAAABBBBBBBBBB 209 SFL Marking of a subset of the packets across a 210 packet loss measurement boundary 212 (4) AACDCDCDAABBBBBBBBBBAAAAAAAAAABBBBBBBBBB 214 The case of multiple delay measurements within 215 a packet loss measurement 217 Figure 1: RFC6734 Query Packet with SFL 219 In case 1 of Figure 1 we show the case were loss measurement alone is 220 being carried out on the flow under analysis. For illustrative 221 purposes consider that in the time interval being analyzed, 10 222 packets always flow. 224 Now consider case 2 of Figure 1 where a small batch of packets need 225 to analyzed for delay. These are marked with a different SFL type 226 indicating that they are to be monitored for both loss and delay. 227 The SFL=A indicates loss batch A, SFL=D indicates a batch of packets 228 that are to be instrumented for delay, but SFL D is synonymous with 229 SFL A, which in turn is synonymous with the underlying FEC. Thus a 230 packet marked D will be accumulated into the A loss batch, into the 231 delay statistics and will be forwarded as normal. Whether the packet 232 is actually counted twice (for loss and delay) or whether the two 233 counters are reconciled during reporting is a local matter. 235 Now consider case 3 of Figure 1 where a small batch of packets are 236 marked for delay across a loss batch boundary. These packets need to 237 considered as part of batch A or a part of batch B, and any RFC6374 238 Query needs to take place after all the packets A or D (which ever 239 option is chosen) have arrived at the receiving LSR. 241 Now consider case 4 of Figure 1. Here we have a case where it is 242 required to take a number of delay measurements within a batch of 243 packets that we are measuring for loss. To do this we need two SFLs 244 for delay (C and D) and alternate between them (on a delay batch by 245 delay batch basis) for the purposes of measuring the delay 246 characteristics of the different batches of packets. 248 6. Some Simplifying Rules 250 It is possible to construct a large set of overlapping measurement 251 type, in terms of loss, delay, loss and delay and batch overlap. If 252 we allow all combination of cases, this leads to configuration, 253 testing and implementation complexity and hence increased operation 254 and capital cost. The following simplifying rules represent the 255 default case: 257 1. Any system that needs to measure delay MUST be able to measure 258 loss. 260 2. Any system that is to measure delay MUST be configured to measure 261 loss. Whether the loss statistics are collected or not is a 262 local matter. 264 3. A delay measurement MAY start at any point during a loss 265 measurement batch, subject to rule 4. 267 4. A delay measurement interval MUST be short enough that it will 268 complete before the enclosing loss batch completes. 270 5. The duration of a second delay (D in Figure 1 batch must be such 271 that all packets from the packets belonging to a first delay 272 batch (C in Figure 1)will have been received before the second 273 delay batch completes. 275 Given that the sender controls both the start and duration of a loss 276 and a delay packet batch, these rules are readily implemented in the 277 control plane. 279 7. Multiple Packet Delay Characteristics 281 A number of methods are described. The expectation is that the MPLS 282 WG possibly with the assistance of the IPPM WG will select one or 283 maybe more than one of these methods for standardization. 285 Three Methods are discussed: 287 1. Time Buckets 289 2. Classic Standard Deviation 291 3. Average Delay 293 7.1. Method 1: Time Buckets 295 In this method the receiving LSR measures the inter-packet gap, 296 classifies the delay into a number of delay buckets and records the 297 number of packets in each bucket. As an example, if the operator 298 were concerned about packets with a delay of up to 1us, 2us, 4us, 299 8us, and over 8us then there would be five buckets and packets that 300 arrived up to 1us would cause the 1us bucket counter to increase, 301 between 1us and 2us the 2us bucket counter would increase etc. In 302 practice it might be better in terms of processing and potential 303 parallelism if, when a packet had a delay relative to its predecessor 304 of 2us both the up to 1us and the 2us counter were incremented and 305 any more detailed information was calculated in the analytics system. 307 This method allows the operator to see more structure in the jitter 308 characteristics than simply measuring the average jitter, and avoids 309 the complication of needing to perform a per packet multiply, but 310 will probably need to time intervals between buckets to be 311 programmable by the operator. 313 The packet format of an RFC6374 Bucket Jitter Measurement Message is 314 shown below: 316 0 1 2 3 317 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 1 318 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 319 |Version| Flags | Control Code | Message Length | 320 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 321 | QTF | RTF | RPTF | Reserved | 322 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 323 | Session Identifier | DS | 324 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 325 | Number of | Reserved | 326 | Buckets | | 327 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 328 | Interval in 10ns units | 329 | | 330 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 331 | Number pkts in Bucket | 332 | | 333 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 334 ~ ~ 335 ~ ~ 336 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 337 ~ ~ 338 ~ TLV Block ~ 339 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 341 Figure 2: Bucket Jitter Measurement Message Format 343 The Version, Flags, Control Code, Message Length, QTF, RTF, RPTF, 344 Session Identifier, and DS Fields are as defined in section 3.7 of 345 RFC6374. The remaining fields are as follows: 347 o Number of Buckets in the measurement 349 o Reserved must be sent as zero and ignored on receipt 351 o Interval in 10ns units is the inter-packet interval for 352 this bucket 354 o Number Pkts in Bucket is the number of packets found in 355 this bucket. 357 There will be a number of Interval/Number pairs depending on the 358 number of buckets being specified by the Querier. If an RFC6374 359 message is being used to configure the buckets, (i.e. the responder 360 is creating or modifying the buckets according to the intervals in 361 the Query message), then the Responder MUST respond with 0 packets in 362 each bucket until it has been configured for a full measurement 363 period. This indicates that it was configured at the time of the 364 last response message, and thus the response is valid for the whole 365 interval. As per the [RFC6374] convention the Number of pkts in 366 Bucket fields are included in the Query message and set to zero. 368 Out of band configuration is permitted by this mode of operation. 370 Note this is a departure from the normal fixed format used in 371 RFC6374. We need to establish if this is problematic or not. 373 This RFC6374 message is carried over an LSP in the way described in 374 [RFC6374] and over an LSP with an SFL as described in Section 9. 376 7.2. Method 2 Classic Standard Deviation 378 In this method, provision is made for reporting the following delay 379 characteristics: 381 1. Number of packets in the batch (n). 383 2. Sum of delays in a batch (S) 385 3. Maximum Delay. 387 4. Minimum Delay. 389 5. Sum of squares of Inter-packet delay (SS). 391 Characteristic's 1 and 2 give the mean delay. Measuring the delay of 392 each pair in the batch is discussed in Section 7.3. 394 Characteristics 3 and 4 give the outliers. 396 Characteristics 1, 2 and 5 can be used to calculate the variance of 397 the inter-packet gap and hence the standard deviation giving a view 398 of the distribution of packet delays and hence the jitter. The 399 equation for the variance (var) is given by: 401 var = (SS - S*S/n)/(n-1) 403 There is some concern over the use of this algorithm for measuring 404 variance, because SS and S*S/n can be similar numbers, particularly 405 where variance is low. However the method commends it self by not 406 requiring a division in the hardware. A future version of this 407 document will look at using improved statistical methods such as the 408 assumed mean. 410 7.2.1. RFC6374 Multi-Packet Delay Measurement Message Format 412 The packet format of an RFC6374 Multi-Packet Delay Measurement 413 Message is shown below: 415 0 1 2 3 416 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 1 417 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 418 |Version| Flags | Control Code | Message Length | 419 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 420 | QTF | RTF | RPTF | Reserved | 421 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 422 | Session Identifier | DS | 423 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 424 | Number of Packets | 425 | | 426 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 427 | Sum of Delays for Batch | 428 | | 429 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 430 | Minimum Delay | 431 | | 432 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 433 | Maximum Delay | 434 | | 435 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 436 | Sum of squares of Inter-packet delay | 437 | | 438 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 439 ~ ~ 440 ~ TLV Block ~ 441 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 443 Figure 3: Multi-packet Delay Measurement Message Format 445 The Version, Flags, Control Code, Message Length, QTF, RTF, RPTF, 446 Session Identifier, and DS Fields are as defined in section 3.7 of 447 RFC6374. The remaining fields are as follows: 449 o Number of Packets is the number of packets in this batch 451 o Sum of Delays for Batch is the duration of the batch in the 452 time measurement format specified in the RTF field. 454 o Minimum Delay is the minimum inter-packet gap observed during 455 the batch in the time format specified in the RTF field. 457 o Maximum Delay is the maximum inter-packet gap observed during 458 the batch in the time format specified in the RTF field. 460 This RFC6374 message is carried over an LSP in the way described in 461 [RFC6374] and over an LSP with an SFL as described in Section 9. 463 7.3. Per Packet Delay Measurement 465 If detailed packet delay measurement is required then it might be 466 possible to record the inter-packet gap for each packet pair. In 467 other that exception cases of slow flows or small batch sizes, this 468 would create a large demand on storage in the instrumentation system, 469 bandwidth to such a storage system and bandwidth to the analytics 470 system. Such a measurement technique is outside the scope of this 471 document. 473 7.4. Average Delay 475 Introduced in [I-D.ietf-ippm-alt-mark] is the concept of a one way 476 delay measurement in which the average time of arrival of a set of 477 packets is measured. In this approach the packet is time-stamped at 478 arrival and the Responder returns the sum of the time-stamps and the 479 number of times-tamps. From this the analytics engine can determine 480 the mean delay. An alternative model is that the Responder returns 481 the time stamp of the first and last packet and the number of 482 packets. This method has the advantage of allowing the average delay 483 to be determined at a number of points along the packet path and 484 allowing the components of the delay to be characterized. 486 The packet format of an RFC6374 Average Delay Measurement Message is 487 shown below: 489 0 1 2 3 490 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 1 491 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 492 |Version| Flags | Control Code | Message Length | 493 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 494 | QTF | RTF | RPTF | Reserved | 495 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 496 | Session Identifier | DS | 497 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 498 | Number of Packets | 499 | | 500 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 501 | Time of First Packet | 502 | | 503 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 504 | Time of Last Packet | 505 | | 506 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 507 | Sum of Timestamps of Batch | 508 | | 509 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 511 ~ ~ 512 ~ TLV Block ~ 513 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 515 Figure 4: Average Delay Measurement Message Format 517 The Version, Flags, Control Code, Message Length, QTF, RTF, RPTF, 518 Session Identifier, and DS Fields are as defined in section 3.7 of 519 RFC6374. The remaining fields are as follows: 521 o Number of Packets is the number of packets in this batch. 523 o Time of First Packet is the time of arrival of the first 524 packet in the batch. 526 o Time of Last Packet is the time of arrival of the last 527 packet in the batch. 529 o Sum of Timestamps of Batch. 531 This RFC6374 message is carried over an LSP in the way described in 532 [RFC6374] and over an LSP with an SFL as described in Section 9. As 533 is the convention with RFC6374, the Query message contains 534 placeholders for the Response message. The placeholders are sent as 535 zero. 537 8. Sampled Measurement 539 In the discussion so far it has been assumed that we would measure 540 the delay characteristics of every packet in a delay measurement 541 interval defined by an SL of constant colour. In 542 [I-D.ietf-ippm-alt-mark] the concept of a sampled measurement is 543 considered. That is the Responder only measures a packet at the 544 start of a group of packets being marked for delay measurement by a 545 particular colour, rather than every packet in the marked batch. A 546 measurement interval is not defined by the duration of a marked batch 547 of packets but the interval between a pair of RFC6374 packets taking 548 a readout of the delay characteristic. This approach has the 549 advantage that the measurement is not impacted by ECMP effects. 551 9. Carrying RFC6374 Packets over an LSP using an SFL 553 The packet format of an RFC6374 Query message using SFLs is shown in 554 Figure 5. 556 +-------------------------------+ 557 | | 558 | LSP | 559 | Label | 560 +-------------------------------+ 561 | | 562 | Synonymous Flow | 563 | Label | 564 +-------------------------------+ 565 | | 566 | GAL | 567 | | 568 +-------------------------------+ 569 | | 570 | ACH Type = 0xA | 571 | | 572 +-------------------------------+ 573 | | 574 | RFC6374 Measurement Message | 575 | | 576 | +-------------------------+ | 577 | | | | 578 | | RFC6374 Fixed | | 579 | | Header | | 580 | | | | 581 | +-------------------------+ | 582 | | | | 583 | | Optional SFL TLV | | 584 | | | | 585 | +-------------------------+ | 586 | | | | 587 | | Optional Return | | 588 | | Information | | 589 | | | | 590 | +-------------------------+ | 591 | | 592 +-------------------------------+ 594 Figure 5: RFC6734 Query Packet with SFL 596 The MPLS label stack is exactly the same as that used for the user 597 data service packets being instrumented except for the inclusion of 598 the GAL [RFC5586] to allow the receiver to distinguish between normal 599 data packets and OAM packets. Since the packet loss measurements are 600 being made on the data service packets, an RFC6374 direct loss 601 measurement is being made, and which is indicated by the type field 602 in the ACH (Type = 0x000A). 604 The RFC6374 measurement message consists of the three components, the 605 RFC6374 fixed header as specified in [RFC6374] carried over the ACH 606 channel type specified the type of measurement being made (currently: 607 loss, delay or loss and delay) as specified in RFC6374. 609 Two optional TLVs MAY also be carried if needed. The first is the 610 SFL TLV specified in Section 9.1. This is used to provide the 611 implementation with a reminder of the SFL that was used to carry the 612 RFC6374 message. This is needed because a number of MPLS 613 implementations do not provide the MPLS label stack to the MPLS OAM 614 handler. This TLV is required if RFC6374 messages are sent over UDP 615 [RFC7876]. This TLV MUST be included unless, by some method outside 616 the scope of this document, it is known that this information is not 617 needed by the RFC6374 Responder. 619 The second set of information that may be needed is the return 620 information that allows the responder send the RFC6374 response to 621 the Querier. This is not needed if the response is requested in-band 622 and the MPLS construct being measured is a point to point LSP, but 623 otherwise MUST be carried. The return address TLV is defined in 624 RFC6378 and the optional UDP Return Object is defined in [RFC7876]. 626 9.1. RFC6374 SFL TLV 628 Editor's Note we need to review the following in the light of further 629 thoughts on the associated signaling protocol(s). I am fairly 630 confident that we need all the fields other than SFL Batch and SFL 631 Index. The Index is useful in order to map between the label and 632 information associated with the FEC. The batch is part of the 633 lifetime management process. 635 The required RFC6374 SFL TLV is shown in Figure 6. This contains the 636 SFL that was carried in the label stack, the FEC that was used to 637 allocate the SFL and the index into the batch of SLs that were 638 allocated for the FEC that corresponds to this SFL. 640 0 1 2 3 641 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 1 642 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 643 | Type | Length |MBZ| SFL Batch | SFL Index | 644 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 645 | SFL | Reserved | 646 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 647 | FEC | 648 . . 649 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 651 Figure 6: SFL TLV 653 Where: 655 Type Type is set to Synonymous Flow Label (SFL-TLV). 657 Length The length of the TLV as specified in RFC6374. 659 MBZ MUST be sent as zero and ignored on receive. 661 SFL Batch The SFL batch that this SFL was allocated as part 662 of see [I-D.bryant-mpls-sfl-control] 664 SPL Index The index into the list of SFLs that were assigned 665 against the FEC that corresponds to the SFL. 667 SFL The SFL used to deliver this packet. This is an MPLS 668 label which is a component of a label stack entry as 669 defined in Section 2.1 of [RFC3032]. 671 Reserved MUST be sent as zero and ignored on receive. 673 FEC The Forwarding Equivalence Class that was used to 674 request this SFL. This is encoded as per 675 Section 3.4.1 of TBD 677 This information is needed to allow for operation with hardware that 678 discards the MPLS label stack before passing the remainder of the 679 stack to the OAM handler. By providing both the SFL and the FEC plus 680 index into the array of allocated SFLs a number of implementation 681 types are supported. 683 10. Applicability to Pro-active and On-demand Measurement 685 A future version of the this document will discuss the applicability 686 of the various methods to pro-active and on-demand Measurement. 688 11. RFC6374 Combined Loss-Delay Measurement 690 This mode of operation is not currently supported by this 691 specification. 693 12. Privacy Considerations 695 The inclusion of originating and/or flow information in a packet 696 provides more identity information and hence potentially degrades the 697 privacy of the communication. Whilst the inclusion of the additional 698 granularity does allow greater insight into the flow characteristics 699 it does not specifically identify which node originated the packet 700 other than by inspection of the network at the point of ingress, or 701 inspection of the control protocol packets. This privacy threat may 702 be mitigated by encrypting the control protocol packets, regularly 703 changing the synonymous labels and by concurrently using a number of 704 such labels. 706 13. Security Considerations 708 The issue noted in Section 5 is a security consideration. There are 709 no other new security issues associated with the MPLS dataplane. Any 710 control protocol used to request SFLs will need to ensure the 711 legitimacy of the request. 713 14. IANA Considerations 715 14.1. Allocation of PW Associated Channel Type 717 As per the IANA considerations in [RFC5586], IANA is requested to 718 allocate the following Channel Type in the "PW Associated Channel 719 Type" registry: 721 Value Description TLV Follows Reference 722 ----- --------------------------------- ----------- --------- 723 TBD RFC6374 Bucket Jitter Measurement No This 725 TBD RFC6374 Multi-Packet Delay No This 726 Measurement 728 TBD RFC6374 Average Delay Measurement No This 730 14.2. MPLS Loss/Delay TLV Object 732 IANA is request to allocate a new TLV from the 0-127 range on the 733 MPLS Loss/Delay Measurement TLV Object Registry: 735 Type Description Reference 736 ---- --------------------------------- --------- 737 TBD Synonymous Flow Label This 739 A value of 4 is recommended. 741 15. References 743 15.1. Normative References 745 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 746 Requirement Levels", BCP 14, RFC 2119, 747 DOI 10.17487/RFC2119, March 1997, 748 . 750 [RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y., 751 Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack 752 Encoding", RFC 3032, DOI 10.17487/RFC3032, January 2001, 753 . 755 [RFC5586] Bocci, M., Ed., Vigoureux, M., Ed., and S. Bryant, Ed., 756 "MPLS Generic Associated Channel", RFC 5586, 757 DOI 10.17487/RFC5586, June 2009, 758 . 760 [RFC6374] Frost, D. and S. Bryant, "Packet Loss and Delay 761 Measurement for MPLS Networks", RFC 6374, 762 DOI 10.17487/RFC6374, September 2011, 763 . 765 [RFC7876] Bryant, S., Sivabalan, S., and S. Soni, "UDP Return Path 766 for Packet Loss and Delay Measurement for MPLS Networks", 767 RFC 7876, DOI 10.17487/RFC7876, July 2016, 768 . 770 15.2. Informative References 772 [I-D.bryant-mpls-sfl-control] 773 Bryant, S., Swallow, G., and S. Sivabalan, "MPLS Flow 774 Identification Considerations", draft-bryant-mpls-sfl- 775 control-01 (work in progress), March 2017. 777 [I-D.bryant-mpls-sfl-framework] 778 Bryant, S., Chen, M., Li, Z., Swallow, G., Sivabalan, S., 779 and G. Mirsky, "Synonymous Flow Label Framework", draft- 780 bryant-mpls-sfl-framework-04 (work in progress), April 781 2017. 783 [I-D.chen-ippm-coloring-based-ipfpm-framework] 784 Chen, M., Zheng, L., Mirsky, G., Fioccola, G., and T. 785 Mizrahi, "IP Flow Performance Measurement Framework", 786 draft-chen-ippm-coloring-based-ipfpm-framework-06 (work in 787 progress), March 2016. 789 [I-D.ietf-ippm-alt-mark] 790 Fioccola, G., Capello, A., Cociglio, M., Castaldelli, L., 791 Chen, M., Zheng, L., Mirsky, G., and T. Mizrahi, 792 "Alternate Marking method for passive performance 793 monitoring", draft-ietf-ippm-alt-mark-04 (work in 794 progress), March 2017. 796 [I-D.ietf-mpls-flow-ident] 797 Bryant, S., Pignataro, C., Chen, M., Li, Z., and G. 798 Mirsky, "MPLS Flow Identification Considerations", draft- 799 ietf-mpls-flow-ident-04 (work in progress), February 2017. 801 [I-D.tempia-ippm-p3m] 802 Capello, A., Cociglio, M., Fioccola, G., Castaldelli, L., 803 and A. Bonda, "A packet based method for passive 804 performance monitoring", draft-tempia-ippm-p3m-03 (work in 805 progress), March 2016. 807 [RFC3270] Le Faucheur, F., Wu, L., Davie, B., Davari, S., Vaananen, 808 P., Krishnan, R., Cheval, P., and J. Heinanen, "Multi- 809 Protocol Label Switching (MPLS) Support of Differentiated 810 Services", RFC 3270, DOI 10.17487/RFC3270, May 2002, 811 . 813 [RFC5921] Bocci, M., Ed., Bryant, S., Ed., Frost, D., Ed., Levrau, 814 L., and L. Berger, "A Framework for MPLS in Transport 815 Networks", RFC 5921, DOI 10.17487/RFC5921, July 2010, 816 . 818 Authors' Addresses 820 Stewart Bryant 821 Huawei 823 Email: stewart.bryant@gmail.com 825 Mach Chen 826 Huawei 828 Email: mach.chen@huawei.com 830 Zhenbin Li 831 Huawei 833 Email: lizhenbin@huawei.com 834 George Swallow 835 Cisco Systems 837 Email: swallow.ietf@gmail.com 839 Siva Sivabalan 840 Cisco Systems 842 Email: msiva@cisco.com 844 Gregory Mirsky 845 ZTE Corp. 847 Email: gregimirsky@gmail.com 849 Giuseppe Fioccola 850 Telecom Italia 852 Email: giuseppe.fioccola@telecomitalia.it