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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 6MAN Working Group G. Fioccola 3 Internet-Draft T. Zhou 4 Intended status: Standards Track Huawei 5 Expires: April 16, 2021 M. Cociglio 6 Telecom Italia 7 F. Qin 8 China Mobile 9 R. Pang 10 China Unicom 11 October 13, 2020 13 IPv6 Application of the Alternate Marking Method 14 draft-ietf-6man-ipv6-alt-mark-02 16 Abstract 18 This document describes how the Alternate Marking Method can be used 19 as the passive performance measurement tool in an IPv6 domain and 20 reports implementation considerations. It proposes how to define a 21 new Extension Header Option to encode alternate marking technique and 22 both Hop-by-Hop Options Header and Destination Options Header are 23 considered. 25 Requirements Language 27 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 28 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 29 document are to be interpreted as described in BCP 14 [RFC2119] 30 [RFC8174] when, and only when, they appear in all capitals, as shown 31 here. 33 Status of This Memo 35 This Internet-Draft is submitted in full conformance with the 36 provisions of BCP 78 and BCP 79. 38 Internet-Drafts are working documents of the Internet Engineering 39 Task Force (IETF). Note that other groups may also distribute 40 working documents as Internet-Drafts. The list of current Internet- 41 Drafts is at https://datatracker.ietf.org/drafts/current/. 43 Internet-Drafts are draft documents valid for a maximum of six months 44 and may be updated, replaced, or obsoleted by other documents at any 45 time. It is inappropriate to use Internet-Drafts as reference 46 material or to cite them other than as "work in progress." 48 This Internet-Draft will expire on April 16, 2021. 50 Copyright Notice 52 Copyright (c) 2020 IETF Trust and the persons identified as the 53 document authors. All rights reserved. 55 This document is subject to BCP 78 and the IETF Trust's Legal 56 Provisions Relating to IETF Documents 57 (https://trustee.ietf.org/license-info) in effect on the date of 58 publication of this document. Please review these documents 59 carefully, as they describe your rights and restrictions with respect 60 to this document. Code Components extracted from this document must 61 include Simplified BSD License text as described in Section 4.e of 62 the Trust Legal Provisions and are provided without warranty as 63 described in the Simplified BSD License. 65 Table of Contents 67 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 68 2. Alternate Marking application to IPv6 . . . . . . . . . . . . 3 69 3. Definition of the AltMark Option . . . . . . . . . . . . . . 4 70 3.1. Data Fields Format . . . . . . . . . . . . . . . . . . . 4 71 4. Use of the AltMark Option . . . . . . . . . . . . . . . . . . 5 72 5. Alternate Marking Method Operation . . . . . . . . . . . . . 7 73 5.1. Packet Loss Measurement . . . . . . . . . . . . . . . . . 7 74 5.2. Packet Delay Measurement . . . . . . . . . . . . . . . . 8 75 5.3. Flow Monitoring Identification . . . . . . . . . . . . . 10 76 5.3.1. Uniqueness of FlowMonID . . . . . . . . . . . . . . . 10 77 5.4. Multipoint and Clustered Alternate Marking . . . . . . . 11 78 5.5. Data Collection and Calculation . . . . . . . . . . . . . 11 79 6. Security Considerations . . . . . . . . . . . . . . . . . . . 11 80 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 81 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13 82 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 83 9.1. Normative References . . . . . . . . . . . . . . . . . . 13 84 9.2. Informative References . . . . . . . . . . . . . . . . . 13 85 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14 87 1. Introduction 89 [RFC8321] and [RFC8889] describe a passive performance measurement 90 method, which can be used to measure packet loss, latency and jitter 91 on live traffic. Since this method is based on marking consecutive 92 batches of packets, the method is often referred as Alternate Marking 93 Method. 95 The Alternate Marking Method has become mature to be implemented and 96 encoded in the IPv6 protocol and this document defines how it can be 97 used to measure packet loss and delay metrics in IPv6. 99 The format of the IPv6 addresses is defined in [RFC4291] while 100 [RFC8200] defines the IPv6 Header, including a 20-bit Flow Label and 101 the IPv6 Extension Headers. The Segment Routing Header (SRH) is 102 defined in [RFC8754] to apply Segment Routing over IPv6 dataplane 103 (SRv6). 105 [I-D.fioccola-v6ops-ipv6-alt-mark] reported a summary on the possible 106 implementation options for the application of the Alternate Marking 107 Method in an IPv6 domain. This document, starting from the outcome 108 of [I-D.fioccola-v6ops-ipv6-alt-mark], introduces a new TLV that can 109 be encoded in the Options Headers (both Hop-by-Hop or Destination) 110 for the purpose of the Alternate Marking Method application in an 111 IPv6 domain. The case of SRH ([RFC8754]) is also discussed, anyway 112 this is valid for all the types of Routing Header (RH). 114 2. Alternate Marking application to IPv6 116 The Alternate Marking Method requires a marking field. As mentioned, 117 several alternatives have been analysed in 118 [I-D.fioccola-v6ops-ipv6-alt-mark] such as IPv6 Extension Headers, 119 IPv6 Address and Flow Label. 121 In consequence to the previous document and to the discussion within 122 the community, it is possible to state that the only correct and 123 robust choice that can actually be standardized would be the use of a 124 new TLV to be encoded in the Options Header (Hop-by-Hop or 125 Destination Option). 127 This approach is compliant with [RFC8200] indeed the Alternate 128 Marking application to IPv6 involves the following operations: 130 o The source node is the only one that writes the Option Header to 131 mark alternately the flow (for both Hop-by-Hop and Destination 132 Option). 134 o In case of Hop-by-Hop Option Header carrying Alternate Marking 135 bits, it is not inserted or deleted, but can be read by any node 136 along the path. The intermediate nodes may be configured to 137 support this Option or not. Anyway this does not impact the 138 traffic since the measurement can be done only for the nodes 139 configured to read the Option. 141 o In case of Destination Option Header carrying Alternate Marking 142 bits, it is not processed, inserted, or deleted by any node along 143 the path until the packet reaches the destination node. Note 144 that, if there is also a Routing Header (RH), any visited 145 destination in the route list can process the Option Header. 147 Hop-by-Hop Option Header is also useful to signal to routers on the 148 path to process the Alternate Marking, anyway it is to be expected 149 that some routers cannot process it unless explicitly configured. 151 The optimization of both implementation and scaling of the Alternate 152 Marking Method is also considered and a way to identify flows is 153 required. The Flow Monitoring Identification field (FlowMonID), as 154 introduced in the next sections, goes in this direction and it is 155 used to identify a monitored flow. 157 Note that the FlowMonID is different from the Flow Label field of the 158 IPv6 Header ([RFC8200]). Flow Label is used for application service, 159 like load-balancing/equal cost multi-path (LB/ECMP) and QoS. 160 Instead, FlowMonID is only used to identify the monitored flow. The 161 reuse of flow label field for identifying monitored flows is not 162 considered since it may change the application intent and forwarding 163 behaviour. Furthermore the flow label may be changed en route and 164 this may also violate the measurement task. Those reasons make the 165 definition of the FlowMonID necessary for IPv6. Flow Label and 166 FlowMonID within the same packet have different scope, identify 167 different flows, and associate different uses. 169 An important point that will also be discussed in this document is 170 the the uniqueness of the FlowMonID and how to allow disambiguation 171 of the FlowMonID in case of collision. [RFC6437] states that the 172 Flow Label cannot be considered alone to avoid ambiguity since it 173 could be accidentally or intentionally changed en route for 174 compelling operational security reasons and this could also happen to 175 the IP addresses that can change due to NAT. But the Alternate 176 Marking is usually applied in a controlled domain, which would not 177 have NAT and there is no security issue that would necessitate 178 rewriting Flow Labels. So, for the purposes of this document, both 179 IP addresses and Flow Label should not change in flight and, in some 180 cases, they could be considered together with the FlowMonID for 181 disambiguation. 183 3. Definition of the AltMark Option 185 The desired choice is to define a new TLV for the Options Extension 186 Headers, carrying the data fields dedicated to the alternate marking 187 method. 189 3.1. Data Fields Format 191 The following figure shows the data fields format for enhanced 192 alternate marking TLV. This AltMark data is expected to be 193 encapsulated in the IPv6 Options Headers (Hop-by-Hop or Destination 194 Option). 196 0 1 2 3 197 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 1 198 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 199 | Option Type | Opt Data Len | 200 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 201 | FlowMonID |L|D| Reserved | 202 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 204 where: 206 o Option Type: 8 bit identifier of the type of Option that needs to 207 be allocated. Unrecognised Types MUST be ignored on receipt. For 208 Hop-by-Hop Options Header or Destination Options Header, [RFC8200] 209 defines how to encode the three high-order bits of the Option Type 210 field. The two high-order bits specify the action that must be 211 taken if the processing IPv6 node does not recognize the Option 212 Type; for AltMark these two bits MUST be set to 00 (skip over this 213 Option and continue processing the header). The third-highest- 214 order bit specifies whether or not the Option Data can change en 215 route to the packet's final destination; for AltMark the value of 216 this bit MUST be set to 0 (Option Data does not change en route). 218 o Opt Data Len: The length of the Option Data Fields of this Option 219 in bytes. 221 o FlowMonID: 20 bits unsigned integer. The FlowMon identifier is 222 described hereinafter. 224 o L: Loss flag for Packet Loss Measurement as described hereinafter; 226 o D: Delay flag for Single Packet Delay Measurement as described 227 hereinafter; 229 o Reserved: is reserved for future use. These bits MUST be set to 230 zero on transmission and ignored on receipt. 232 4. Use of the AltMark Option 234 The AltMark Option is the best way to implement the Alternate Marking 235 method and can be carried by the Hop-by-Hop Options header and the 236 Destination Options header. In case of Destination Option, it is 237 processed only by the source and destination nodes: the source node 238 inserts and the destination node removes it. While, in case of Hop- 239 by-Hop Option, it may be examined by any node along the path, if 240 explicitly configured to do so. In this way an unrecognized Hop-by- 241 Hop Option may be just ignored without impacting the traffic. 243 So it is important to highlight that the Option Layout can be used 244 both as Destination Option and as Hop-by-Hop Option depending on the 245 Use Cases and it is based on the chosen type of performance 246 measurement. In general, it is needed to perform both end to end and 247 hop by hop measurements, and the alternate marking methodology 248 allows, by definition, both performance measurements. Anyway, in 249 many cases the end-to-end measurement is not enough and it is 250 required also the hop-by-hop measurement, so the most complete choice 251 is the Hop-by-Hop Options Header. 253 IPv6, as specified in [RFC8200], allows nodes to optionally process 254 Hop-by-Hop headers. Specifically the Hop-by-Hop Options header is 255 not inserted or deleted, but may be examined or processed by any node 256 along a packet's delivery path, until the packet reaches the node (or 257 each of the set of nodes, in the case of multicast) identified in the 258 Destination Address field of the IPv6 header. Also, it is expected 259 that nodes along a packet's delivery path only examine and process 260 the Hop-by-Hop Options header if explicitly configured to do so. 262 The Hop-by-Hop Option defined in this document is designed to take 263 advantage of the property of how Hop-by-Hop options are processed. 264 Nodes that do not support this Option SHOULD ignore them. This can 265 mean that, in this case, the performance measurement does not account 266 for all links and nodes along a path. 268 Another application that can be mentioned is the presence of a 269 Routing Header, in particular it is possible to consider SRv6. SRv6 270 leverages the Segment Routing header which consists of a new type of 271 routing header. Like any other use case of IPv6, Hop-by-Hop and 272 Destination Options are useable when SRv6 header is present. Because 273 SRv6 is implemented through a Segment Routing Header (SRH), 274 Destination Options before the Routing Header are processed by each 275 destination in the route list, that means, in case of SRH, by every 276 node that is an identity in the SR path. 278 In summary, it is possible to list the alternative possibilities: 280 o Destination Option => measurement only by node in Destination 281 Address. 283 o Hop-by-Hop Option => every router on the path with feature 284 enabled. 286 o Destination Option + any Routing Header => every destination node 287 in the route list. 289 In general, Hop-by-Hop and Destination Options are the most suitable 290 ways to implement Alternate Marking. 292 It is worth mentioning that new Hop-by-Hop Options are not strongly 293 recommended in [RFC7045] and [RFC8200], unless there is a clear 294 justification to standardize it, because nodes may be configured to 295 ignore the Options Header, drop or assign packets containing an 296 Options Header to a slow processing path. In case of the AltMark 297 data fields described in this document, the motivation to standardize 298 a new Hop-by-Hop Option is that it is needed for OAM. An 299 intermediate node can read it or not but this does not affect the 300 packet behavior. The source node is the only one that writes the 301 Hop-by-Hop Option to mark alternately the flow, so, the performance 302 measurement can be done for those nodes configured to read this 303 Option, while the others are simply not considered for the metrics. 305 In addition to the previous alternatives, for legacy network it is 306 possible to mention a non-conventional application of the Destination 307 Option for the hop by hop usage. [RFC8200] defines that the nodes 308 along a path examine and process the Hop-by-Hop Options header only 309 if Hop-by-Hop processing is explicitly configured. On the other 310 hand, using the Destination Option for hop by hop action would cause 311 worse performance than Hop-by-Hop. The only motivation for the hop 312 by hop usage of Destination Options can be for compatibility reasons 313 but in general it is not recommended. 315 5. Alternate Marking Method Operation 317 This section describes how the method operates. [RFC8321] introduces 318 several alternatives but in this section the most applicable methods 319 are reported and a new fied is introduced to facilitate the 320 deployment and improve the scalability. 322 5.1. Packet Loss Measurement 324 The measurement of the packet loss is really straightforward. The 325 packets of the flow are grouped into batches, and all the packets 326 within a batch are marked by setting the L bit (Loss flag) to a same 327 value. The source node can switch the value of the L bit between 0 328 and 1 after a fixed number of packets or according to a fixed timer, 329 and this depends on the implementation. By counting the number of 330 packets in each batch and comparing the values measured by different 331 network nodes along the path, it is possible to measure the packet 332 loss occurred in any single batch between any two nodes. Each batch 333 represents a measurable entity unambiguously recognizable by all 334 network nodes along the path. 336 Packets with different L values may get swapped at batch boundaries, 337 and in this case, it is required that each marked packet can be 338 assigned to the right batch by each router. It is important to 339 mention that for the application of this method there are two 340 elements to consider: the clock error between network nodes and the 341 network delay. These can create offsets between the batches and out- 342 of-order of the packets. There is the condition on timing aspects 343 explained in [RFC8321] that must be satisfied and it takes into 344 considerations the different causes of reordering such as clock 345 error, network delay. The consequence is that it is necessary to 346 define a waiting interval where to get stable counters and to avoid 347 these issues. Usually the counters can be taken in the middle of the 348 batch period to be sure to take still counters. In a few words this 349 implies that the length of the batches MUST be chosen large enough so 350 that the method is not affected by those factors. 352 L bit=1 ----------+ +-----------+ +---------- 353 | | | | 354 L bit=0 +-----------+ +-----------+ 355 Batch n ... Batch 3 Batch 2 Batch 1 356 <---------> <---------> <---------> <---------> <---------> 358 Traffic Flow 359 ===========================================================> 360 L bit ...1111111111 0000000000 11111111111 00000000000 111111111... 361 ===========================================================> 363 Figure 1: Packet Loss Measurement and Single-Marking Methodology 364 using L bit 366 5.2. Packet Delay Measurement 368 The same principle used to measure packet loss can be applied also to 369 one-way delay measurement. Delay metrics MAY be calculated using the 370 two possibilities: 372 1. Single-Marking Methodology: This approach uses only the L bit to 373 calculate both packet loss and delay. In this case, the D flag 374 MUST be set to zero on transmit and ignored by the monitoring 375 points. The alternation of the values of the L bit can be used 376 as a time reference to calculate the delay. Whenever the L bit 377 changes and a new batch starts, a network node can store the 378 timestamp of the first packet of the new batch, that timestamp 379 can be compared with the timestamp of the first packet of the 380 same batch on a second node to compute packet delay. Anyway this 381 measurement is accurate only if no packet loss occurs and if 382 there is no packet reordering at the edges of the batches. A 383 different approach can also be considered and it is based on the 384 concept of the mean delay. The mean delay for each batch is 385 calculated by considering the average arrival time of the packets 386 for the relative batch. There are limitations also in this case 387 indeed, each node needs to collect all the timestamps and 388 calculate the average timestamp for each batch. In addition the 389 information is limited to a mean value. 391 2. Double-Marking Methodology: This approach is more complete and 392 uses the L bit only to calculate packet loss and the D bit (Delay 393 flag) is fully dedicated to delay measurements. The idea is to 394 use the first marking with the L bit to create the alternate flow 395 and, within the batches identified by the L bit, a second marking 396 is used to select the packets for measuring delay. The D bit 397 creates a new set of marked packets that are fully identified 398 over the network, so that a network node can store the timestamps 399 of these packets; these timestamps can be compared with the 400 timestamps of the same packets on a second node to compute packet 401 delay values for each packet. The most efficient and robust mode 402 is to select a single double-marked packet for each batch, in 403 this way there is no time gap to consider between the double- 404 marked packets to avoid their reorder. If a double-marked packet 405 is lost, the delay measurement for the considered batch is simply 406 discarded, but this is not a big problem because it is easy to 407 recognize the problematic batch and skip the measurement just for 408 that one. So in order to have more information about the delay 409 and to overcome out-of-order issues this method is preferred. 411 L bit=1 ----------+ +-----------+ +---------- 412 | | | | 413 L bit=0 +-----------+ +-----------+ 415 D bit=1 + + + + + 416 | | | | | 417 D bit=0 ------+----------+----------+----------+------------+----- 419 Traffic Flow 420 ===========================================================> 421 L bit ...1111111111 0000000000 11111111111 00000000000 111111111... 423 D bit ...0000010000 0000010000 00000100000 00001000000 000001000... 424 ===========================================================> 426 Figure 2: Double-Marking Methodology using L bit and D bit 428 Similar to packet delay measurement (both for Single Marking and 429 Double Marking), the method can also be used to measure the inter- 430 arrival jitter. 432 5.3. Flow Monitoring Identification 434 The Flow Monitoring Identification (FlowMonID) is required for some 435 general reasons: 437 o First, it helps to reduce the per node configuration. Otherwise, 438 each node needs to configure an access-control list (ACL) for each 439 of the monitored flows. Moreover, using a flow identifier allows 440 a flexible granularity for the flow definition. 442 o Second, it simplifies the counters handling. Hardware processing 443 of flow tuples (and ACL matching) is challenging and often incurs 444 into performance issues, especially in tunnel interfaces. 446 o Third, it eases the data export encapsulation and correlation for 447 the collectors. 449 The FlowMon identifier field is to uniquely identify a monitored flow 450 within the measurement domain. The field is set at the source node. 451 The FlowMonID can be uniformly assigned by the central controller or 452 algorithmically generated by the source node. The latter approach 453 cannot guarantee the uniqueness of FlowMonID but it may be preferred 454 for local or private network, where the conflict probability is small 455 due to the large FlowMonID space. 457 5.3.1. Uniqueness of FlowMonID 459 It is important to note that if the 20 bit FlowMonID is set 460 independently and pseudo randomly there is a chance of collision. 461 So, in some cases, FlowMonID could not be sufficient for uniqueness. 463 In general the probability of a flow identifier uniqueness correlates 464 to the amount of entropy of the inputs. For instance, using the 465 well-known birthday problem in probability theory, if the 20 bit 466 FlowMonID is set independently and pseudo randomly without any 467 additional input entropy, there is a 50% chance of collision for just 468 1206 flows. For a 32 bit identifier the 50% threshold jumps to 469 77,163 flows and so on. So, for more entropy, FlowMonID can either 470 be combined with other identifying flow information in a packet (e.g. 471 it is possible to consider the hashed 3-tuple Flow Label, Source and 472 Destination addresses) or the FlowMonID size could be increased. 474 This issue is more visible when the FlowMonID is pseudo randomly 475 generated by the source node and there needs to tag it with 476 additional flow information to allow disambiguation. While, in case 477 of a centralized controller, the controller should set FlowMonID by 478 considering these aspects and instruct the nodes properly in order to 479 guarantee its uniqueness. 481 5.4. Multipoint and Clustered Alternate Marking 483 The Alternate Marking method can also be extended to any kind of 484 multipoint to multipoint paths, and the network clustering approach 485 allows a flexible and optimized performance measurement, as described 486 in [RFC8889]. 488 The Cluster is the smallest identifiable subnetwork of the entire 489 Network graph that still satisfies the condition that the number of 490 packets that goes in is the same that goes out. With network 491 clustering, it is possible to use the partition of the network into 492 clusters at different levels in order to perform the needed degree of 493 detail. So, for Multipoint Alternate Marking, FlowMonID can identify 494 in general a multipoint-to-multipoint flow and not only a point-to- 495 point flow. 497 5.5. Data Collection and Calculation 499 The nodes enabled to perform performance monitoring collect the value 500 of the packet counters and timestamps. There are several 501 alternatives to implement Data Collection and Calculation, but this 502 is not specified in this document. 504 6. Security Considerations 506 This document aims to apply a method to perform measurements that 507 does not directly affect Internet security nor applications that run 508 on the Internet. However, implementation of this method must be 509 mindful of security and privacy concerns. 511 There are two types of security concerns: potential harm caused by 512 the measurements and potential harm to the measurements. 514 Harm caused by the measurement: Alternate Marking implies 515 modifications on the fly to an Option Header of IPv6 packets by the 516 source node but this must be performed in a way that does not alter 517 the quality of service experienced by the packets and that preserves 518 stability and performance of routers doing the measurements. The 519 advantage of the Alternate Marking method is that the marking bits 520 are the only information that is exchanged between the network nodes. 521 Therefore, network reconnaissance through passive eavesdropping on 522 data-plane traffic does not allow attackers to gain information about 523 the network performance. Moreover, Alternate Marking should usually 524 be applied in a controlled domain and this also helps to limit the 525 problem. 527 Harm to the Measurement: Alternate Marking measurements could be 528 harmed by routers altering the marking of the packets or by an 529 attacker injecting artificial traffic. Since the measurement itself 530 may be affected by network nodes along the path intentionally 531 altering the value of the marking bits of IPv6 packets, the Alternate 532 Marking should be applied in the context of a controlled domain, 533 where the network nodes are locally administered and this type of 534 attack can be avoided. Indeed the source and destination addresses 535 are within the controlled domain and therefore it is unlikely subject 536 to hijacking of packets, because it is possible to filter external 537 packets at the domain boundaries. In addition, an attacker cannot 538 gain information about network performance from a single monitoring 539 point; it must use synchronized monitoring points at multiple points 540 on the path, because they have to do the same kind of measurement and 541 aggregation as Alternate Marking requires. 543 The privacy concerns of network measurement are limited because the 544 method only relies on information contained in the Option Header 545 without any release of user data. Although information in the Option 546 Header is metadata that can be used to compromise the privacy of 547 users, the limited marking technique seems unlikely to substantially 548 increase the existing privacy risks from header or encapsulation 549 metadata. 551 The Alternate Marking application described in this document relies 552 on an time synchronization protocol. Thus, by attacking the time 553 protocol, an attacker can potentially compromise the integrity of the 554 measurement. A detailed discussion about the threats against time 555 protocols and how to mitigate them is presented in [RFC7384]. 557 7. IANA Considerations 559 The Option Type should be assigned in IANA's "Destination Options and 560 Hop-by-Hop Options" registry. 562 This draft requests the following IPv6 Option Type assignments from 563 the Destination Options and Hop-by-Hop Options sub-registry of 564 Internet Protocol Version 6 (IPv6) Parameters 565 (https://www.iana.org/assignments/ipv6-parameters/). 567 Hex Value Binary Value Description Reference 568 act chg rest 569 ---------------------------------------------------------------- 570 TBD 00 0 tbd AltMark [This draft] 572 8. Acknowledgements 574 The authors would like to thank Bob Hinden, Ole Troan, Tom Herbert, 575 Stefano Previdi, Brian Carpenter, Eric Vyncke, Ron Bonica for the 576 precious comments and suggestions. 578 9. References 580 9.1. Normative References 582 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 583 Requirement Levels", BCP 14, RFC 2119, 584 DOI 10.17487/RFC2119, March 1997, 585 . 587 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 588 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 589 May 2017, . 591 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 592 (IPv6) Specification", STD 86, RFC 8200, 593 DOI 10.17487/RFC8200, July 2017, 594 . 596 9.2. Informative References 598 [I-D.fioccola-v6ops-ipv6-alt-mark] 599 Fioccola, G., Velde, G., Cociglio, M., and P. Muley, "IPv6 600 Performance Measurement with Alternate Marking Method", 601 draft-fioccola-v6ops-ipv6-alt-mark-01 (work in progress), 602 June 2018. 604 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 605 Architecture", RFC 4291, DOI 10.17487/RFC4291, February 606 2006, . 608 [RFC6437] Amante, S., Carpenter, B., Jiang, S., and J. Rajahalme, 609 "IPv6 Flow Label Specification", RFC 6437, 610 DOI 10.17487/RFC6437, November 2011, 611 . 613 [RFC7045] Carpenter, B. and S. Jiang, "Transmission and Processing 614 of IPv6 Extension Headers", RFC 7045, 615 DOI 10.17487/RFC7045, December 2013, 616 . 618 [RFC7384] Mizrahi, T., "Security Requirements of Time Protocols in 619 Packet Switched Networks", RFC 7384, DOI 10.17487/RFC7384, 620 October 2014, . 622 [RFC8321] Fioccola, G., Ed., Capello, A., Cociglio, M., Castaldelli, 623 L., Chen, M., Zheng, L., Mirsky, G., and T. Mizrahi, 624 "Alternate-Marking Method for Passive and Hybrid 625 Performance Monitoring", RFC 8321, DOI 10.17487/RFC8321, 626 January 2018, . 628 [RFC8754] Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J., 629 Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header 630 (SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020, 631 . 633 [RFC8889] Fioccola, G., Ed., Cociglio, M., Sapio, A., and R. Sisto, 634 "Multipoint Alternate-Marking Method for Passive and 635 Hybrid Performance Monitoring", RFC 8889, 636 DOI 10.17487/RFC8889, August 2020, 637 . 639 Authors' Addresses 641 Giuseppe Fioccola 642 Huawei 643 Riesstrasse, 25 644 Munich 80992 645 Germany 647 Email: giuseppe.fioccola@huawei.com 649 Tianran Zhou 650 Huawei 651 156 Beiqing Rd. 652 Beijing 100095 653 China 655 Email: zhoutianran@huawei.com 657 Mauro Cociglio 658 Telecom Italia 659 Via Reiss Romoli, 274 660 Torino 10148 661 Italy 663 Email: mauro.cociglio@telecomitalia.it 664 Fengwei Qin 665 China Mobile 666 32 Xuanwumenxi Ave. 667 Beijing 100032 668 China 670 Email: qinfengwei@chinamobile.com 672 Ran Pang 673 China Unicom 674 9 Shouti South Rd. 675 Beijing 100089 676 China 678 Email: pangran@chinaunicom.cn