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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references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 8321 (Obsoleted by RFC 9341) == Outdated reference: A later version (-09) exists of draft-ietf-ippm-multipoint-alt-mark-06 == Outdated reference: A later version (-21) exists of draft-song-opsawg-ifit-framework-10 Summary: 1 error (**), 0 flaws (~~), 3 warnings (==), 1 comment (--). 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: August 30, 2020 M. Cociglio 6 Telecom Italia 7 F. Qin 8 China Mobile 9 February 27, 2020 11 IPv6 Application of the Alternate Marking Method 12 draft-fz-6man-ipv6-alt-mark-06 14 Abstract 16 This document describes how the Alternate Marking Method can be used 17 as the passive performance measurement tool in an IPv6 domain and 18 reports implementation considerations. It proposes how to define a 19 new Extension Header Option to encode alternate marking technique and 20 also the Segment Routing case is discussed. 22 Requirements Language 24 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 25 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 26 document are to be interpreted as described in RFC 2119 [RFC2119]. 28 Status of This Memo 30 This Internet-Draft is submitted in full conformance with the 31 provisions of BCP 78 and BCP 79. 33 Internet-Drafts are working documents of the Internet Engineering 34 Task Force (IETF). Note that other groups may also distribute 35 working documents as Internet-Drafts. The list of current Internet- 36 Drafts is at https://datatracker.ietf.org/drafts/current/. 38 Internet-Drafts are draft documents valid for a maximum of six months 39 and may be updated, replaced, or obsoleted by other documents at any 40 time. It is inappropriate to use Internet-Drafts as reference 41 material or to cite them other than as "work in progress." 43 This Internet-Draft will expire on August 30, 2020. 45 Copyright Notice 47 Copyright (c) 2020 IETF Trust and the persons identified as the 48 document authors. All rights reserved. 50 This document is subject to BCP 78 and the IETF Trust's Legal 51 Provisions Relating to IETF Documents 52 (https://trustee.ietf.org/license-info) in effect on the date of 53 publication of this document. Please review these documents 54 carefully, as they describe your rights and restrictions with respect 55 to this document. Code Components extracted from this document must 56 include Simplified BSD License text as described in Section 4.e of 57 the Trust Legal Provisions and are provided without warranty as 58 described in the Simplified BSD License. 60 Table of Contents 62 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 63 2. IPv6 application of the Alternate Marking . . . . . . . . . . 3 64 3. Definition of the AltMark TLV . . . . . . . . . . . . . . . . 4 65 3.1. Data Fields Format . . . . . . . . . . . . . . . . . . . 4 66 4. AltMark: EH Option or SRH TLV . . . . . . . . . . . . . . . . 5 67 5. Alternate Marking Method Operation . . . . . . . . . . . . . 6 68 6. Security Considerations . . . . . . . . . . . . . . . . . . . 6 69 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 70 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7 71 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 72 9.1. Normative References . . . . . . . . . . . . . . . . . . 7 73 9.2. Informative References . . . . . . . . . . . . . . . . . 7 74 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 76 1. Introduction 78 [RFC8321] and [I-D.ietf-ippm-multipoint-alt-mark] describe a passive 79 performance measurement method, which can be used to measure packet 80 loss, latency and jitter on live traffic. Since this method is based 81 on marking consecutive batches of packets, the method is often 82 referred as Alternate Marking Method. 84 [I-D.song-opsawg-ifit-framework] introduces the telemetry 85 architecture that can be considered as reference. 87 This document defines how the Alternate Marking Method ([RFC8321]) 88 can be used to measure packet loss and delay metrics in IPv6. 90 The format of the IPv6 addresses is defined in [RFC4291] while 91 [RFC8200] defines the IPv6 Header, including a 20-bit Flow Label and 92 the IPv6 Extension Headers. The Segment Routing Header (SRH) is 93 defined in [I-D.ietf-6man-segment-routing-header]. 95 [I-D.fioccola-v6ops-ipv6-alt-mark] reported a summary on the possible 96 implementation options for the application of the Alternate Marking 97 Method in an IPv6 domain. This document, starting from the outcome 98 of [I-D.fioccola-v6ops-ipv6-alt-mark], introduces a new TLV that can 99 be encoded in the Option Headers (both Hop-by-hop or Destination) for 100 the purpose of the Alternate Marking Method application in an IPv6 101 domain. The case of SRH ([I-D.ietf-6man-segment-routing-header]) is 102 also discussed. 104 2. IPv6 application of the Alternate Marking 106 The Alternate Marking Method requires a marking field. As mentioned, 107 several alternatives have been analysed in 108 [I-D.fioccola-v6ops-ipv6-alt-mark] such as IPv6 Extension Headers, 109 IPv6 Address and Flow Label. 111 The preferred choice would be the use of a new TLV to be encoded in 112 the Option (Hop-by-hop or Destination) header. 114 This approach is compliant with [RFC8200] that clearly states the use 115 of existing EH rather than defining new ones especially with hop by 116 hop behaviour. 118 In order to optimize implementation and scaling of the Alternate 119 Marking Method, a way to identify flows is required. The Flow 120 Monitoring Identification field (FlowMonID), as introduced in the 121 next section, goes in this direction and it is used to identify a 122 monitored flow. 124 The Flow Monitoring Identification (FlowMonID) is required for some 125 general reasons: 127 First, it helps to reduce the per node configuration. Otherwise, 128 each node needs to configure an access-control list (ACL) for each 129 of the monitored flows. Moreover, using a flow identifier allows 130 a flexible granularity for the flow definition. 132 Second, it simplifies the counters handling. Hardware processing 133 of flow tuples (and ACL matching) is challenging and often incurs 134 into performance issues, especially in tunnel interfaces. 136 Third, it eases the data export encapsulation and correlation for 137 the collectors. 139 Note that the FlowMonID is different from the Flow Label field of the 140 IPv6 Header ([RFC8200]). Flow Label is used for application service, 141 like load-balancing/equal cost multi-path (LB/ECMP) and QoS. 142 Instead, FlowMonID is only used to identify the monitored flow. The 143 reuse of flow label field for identifying monitored flows is not 144 considered since it may change the application intent and forwarding 145 behaviour. Furthermore the flow label may be changed en route and 146 this may also violate the measurement task. Those reasons make the 147 definition of the FlowMonID necessary for IPv6. Flow Label and 148 FlowMonID within the same packet have different scope, identify 149 different flows, and associate different uses. 151 3. Definition of the AltMark TLV 153 The desired choice is to define a new TLV for the Option extension 154 headers, carrying the data fields dedicated to the alternate marking 155 method. 157 3.1. Data Fields Format 159 The following figure shows the data fields format for enhanced 160 alternate marking TLV. This AltMark data is expected to be 161 encapsulated in the IPv6 Option (hop-by-hop or destination). 163 0 1 2 3 164 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 1 165 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 166 | Type | Length | 167 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 168 | FlowMonID |L|D| Reserved | 169 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 171 where: 173 o Type/Option Type: 8 bit identifier of the type of Option/TLV that 174 needs to be allocated. Unrecognised Types MUST be ignored on 175 receipt. 177 o Length/Opt Data Len: The length of the length Data Fields of this 178 Option/TLV in bytes. 180 o FlowMonID: 20 bits unsigned integer. The FlowMon identifier field 181 is to uniquely identify a monitored flow within the measurement 182 domain. The field is set at the ingress node. The FlowMonID can 183 be uniformly assigned by the central controller or algorithmically 184 generated by the ingress node. The latter approach cannot 185 guarantee the uniqueness of FlowMonID but it may be preferred for 186 local or private network, where the conflict probability is small 187 due to the large FlowMonID space. 189 o L: Loss flag for Single-Marking as defined in [RFC8321]; 191 o D: Delay flag for Double-Marking as defined in [RFC8321]; 193 o Reserved: is reserved for future use. These bits MUST be set to 194 zero on transmission and ignored on receipt. 196 4. AltMark: EH Option or SRH TLV 198 Using a new EH Option assumes that all routers in the domain support 199 this type of headers even if an unrecognized EH Option may be just 200 ignored without impacting the traffic. So, the new AltMark Option 201 Layout seems the best way to implement the Alternate Marking method. 203 It is important to highlight that the Option Layout can be used both 204 as Destination Option and as Hop-By-Hop Option depending on the Use 205 Cases. In general, it is needed to perform both end-to-end and hop- 206 by-hop measurements, and the alternate marking methodology in 207 [RFC8321] allows, by definition, both performance measurements. 209 Hop-By-Hop Options Header or Destination Options Header can be used 210 based on the chosen type of performance measurement. 212 SRv6 leverages the Segment Routing header which consists of a new 213 type of routing header. Like any other use case of IPv6, HBH and 214 Destination options are useable when SRv6 header is present. Because 215 SRv6 is a routing header, destination options before the routing 216 header are processed by each destination in the route list. 218 SRH TLV can also be used to encode the AltMark Data Fields for SRv6. 219 Furthermore, the intermediated nodes that are not in the SID list may 220 consider the SRH as a green field, therefore they cannot support and 221 bypass or support and dig into the SRH TLV. But the usage of SRH TLV 222 is still under discussion within the community and so it is not the 223 preferred solution. 225 In summary, it is possible to list the alternative options: 227 Destination Option => measurement only by node in Destination 228 Address. 230 Hop-By-Hop Option => every router on the path with feature 231 enabled. 233 SRH TLV => every node that is an identity in the SR path. 235 Destination Option + SRH => every node that is an identity in the 236 SR path. 238 Note that the SRH TLV and Destination Option + SRH could be 239 considered equivalent. Anyway, in general, HBH and Destination 240 options are the most suitable ways to implement Alternate Marking. 242 Both [RFC7045] and [RFC8200] do not recommend the introduction of new 243 Hop-by-Hop Options headers because nodes may be configured to ignore, 244 drop or assign to a slow processing path. But, in case of the 245 AltMark data fields described in this document, the new hop-by-hop 246 option is needed for OAM and an intermediate node can read it or not 247 but, this does not affect the packet behavior. The source node is 248 the only one that writes the hop-by-hop option to mark alternately 249 the flow, so, the performance measurement can be done for those nodes 250 configured to read this option, while the others are simply not 251 considered for the metrics. Moreover, in case of SRv6, the use of 252 SRH TLV for every node along the SR path is a good choice to 253 implement hop-by-hop measurements. 255 In addition to the previous alternatives, for legacy network it is 256 possible to mention a non-conventional application of the SRH TLV and 257 Destination Option for the hop-by-hop usage. [RFC8200] defines that 258 the nodes along a path examine and process the Hop-by-Hop Options 259 header only if HBH processing is explicitly configured. On the other 260 hand, using the SRH TLV or Destination Option for hop-by-hop action 261 would cause worse performance than Hop-By-Hop. The only motivation 262 for the hop-by-hop usage of destination options can be for 263 compatibility reasons but in general it is not recommended. 265 5. Alternate Marking Method Operation 267 [RFC8321] and [I-D.ietf-ippm-multipoint-alt-mark] describe in detail 268 the methodology. 270 6. Security Considerations 272 This document aims to apply a method to perform measurements that 273 does not directly affect Internet security nor applications that run 274 on the Internet. However, implementation of this method must be 275 mindful of security and privacy concerns, as explained in [RFC8321]. 277 7. IANA Considerations 279 The option type should be assigned in IANA's "Destination Options and 280 Hop-by-Hop Options" registry. Also, the TLV type should be assigned 281 from Segment Routing Header TLVs Registry. 283 8. Acknowledgements 285 The authors would like to thank Bob Hinden, Ole Troan, Tom Herbert, 286 Stefano Previdi, Brian Carpenter for the precious comments and 287 suggestions. 289 9. References 291 9.1. Normative References 293 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 294 Requirement Levels", BCP 14, RFC 2119, 295 DOI 10.17487/RFC2119, March 1997, 296 . 298 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 299 (IPv6) Specification", STD 86, RFC 8200, 300 DOI 10.17487/RFC8200, July 2017, 301 . 303 [RFC8321] Fioccola, G., Ed., Capello, A., Cociglio, M., Castaldelli, 304 L., Chen, M., Zheng, L., Mirsky, G., and T. Mizrahi, 305 "Alternate-Marking Method for Passive and Hybrid 306 Performance Monitoring", RFC 8321, DOI 10.17487/RFC8321, 307 January 2018, . 309 9.2. Informative References 311 [I-D.fioccola-v6ops-ipv6-alt-mark] 312 Fioccola, G., Velde, G., Cociglio, M., and P. Muley, "IPv6 313 Performance Measurement with Alternate Marking Method", 314 draft-fioccola-v6ops-ipv6-alt-mark-01 (work in progress), 315 June 2018. 317 [I-D.ietf-6man-segment-routing-header] 318 Filsfils, C., Dukes, D., Previdi, S., Leddy, J., 319 Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header 320 (SRH)", draft-ietf-6man-segment-routing-header-26 (work in 321 progress), October 2019. 323 [I-D.ietf-ippm-multipoint-alt-mark] 324 Fioccola, G., Cociglio, M., Sapio, A., and R. Sisto, 325 "Multipoint Alternate Marking method for passive and 326 hybrid performance monitoring", draft-ietf-ippm- 327 multipoint-alt-mark-06 (work in progress), February 2020. 329 [I-D.song-opsawg-ifit-framework] 330 Song, H., Qin, F., Chen, H., Jin, J., and J. Shin, "In- 331 situ Flow Information Telemetry", draft-song-opsawg-ifit- 332 framework-10 (work in progress), December 2019. 334 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 335 Architecture", RFC 4291, DOI 10.17487/RFC4291, February 336 2006, . 338 [RFC7045] Carpenter, B. and S. Jiang, "Transmission and Processing 339 of IPv6 Extension Headers", RFC 7045, 340 DOI 10.17487/RFC7045, December 2013, 341 . 343 Authors' Addresses 345 Giuseppe Fioccola 346 Huawei 347 Riesstrasse, 25 348 Munich 80992 349 Germany 351 Email: giuseppe.fioccola@huawei.com 353 Tianran Zhou 354 Huawei 355 156 Beiqing Rd. 356 Beijing 100095 357 China 359 Email: zhoutianran@huawei.com 361 Mauro Cociglio 362 Telecom Italia 363 Via Reiss Romoli, 274 364 Torino 10148 365 Italy 367 Email: mauro.cociglio@telecomitalia.it 368 Fengwei Qin 369 China Mobile 370 32 Xuanwumenxi Ave. 371 Beijing 100032 372 China 374 Email: qinfengwei@chinamobile.com