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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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-09) exists of draft-ietf-ippm-multipoint-alt-mark-04 == Outdated reference: A later version (-21) exists of draft-song-opsawg-ifit-framework-10 -- Obsolete informational reference (is this intentional?): RFC 8321 (Obsoleted by RFC 9341) Summary: 0 errors (**), 0 flaws (~~), 3 warnings (==), 2 comments (--). 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: July 31, 2020 M. Cociglio 6 Telecom Italia 7 F. Qin 8 China Mobile 9 January 28, 2020 11 IPv6 Application of the Alternate Marking Method 12 draft-fz-6man-ipv6-alt-mark-05 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 considers the Segment Routing Header TLV alternative. 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 July 31, 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 . . . . . . . . . . . . . . . . . . . . . . 6 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) and 100 in the SRH ([I-D.ietf-6man-segment-routing-header] for the purpose of 101 the Alternate Marking Method application in an IPv6 domain). 103 2. IPv6 application of the Alternate Marking 105 The Alternate Marking Method requires a marking field. As mentioned, 106 several alternatives have been analysed in 107 [I-D.fioccola-v6ops-ipv6-alt-mark] such as IPv6 Extension Headers, 108 IPv6 Address and Flow Label. 110 The preferred choice would be the use of a new TLV to be encoded in 111 the Option (Hop-by-hop or Destination) header and in the SRH. 113 This approach is compliant with [RFC8200] that recommends the use of 114 existing EH rather than defining new ones especially with hop by hop 115 behaviour. 117 In order to optimize implementation and scaling of the Alternate 118 Marking Method, a way to identify flows is required. The Flow 119 Monitoring Identification field (FlowMonID), as introduced in the 120 next section, goes in this direction and it is used to identify a 121 monitored flow. 123 The Flow Monitoring Identification (FlowMonID) is required for some 124 general reasons: 126 First, it helps to reduce the per node configuration. Otherwise, 127 each node needs to configure an access-control list (ACL) for each 128 of the monitored flows. Moreover, using a flow identifier allows 129 a flexible granularity for the flow definition. 131 Second, it simplifies the counters handling. Hardware processing 132 of flow tuples (and ACL matching) is challenging and often incurs 133 into performance issues, especially in tunnel interfaces. 135 Third, it eases the data export encapsulation and correlation for 136 the collectors. 138 Note that the FlowMonID is different from the Flow Label field of the 139 IPv6 Header ([RFC8200]). Flow Label is used for application service, 140 like load-balancing/equal cost multi-path (LB/ECMP) and QoS. 141 Instead, FlowMonID is only used to identify the monitored flow. The 142 reuse of flow label field for identifying monitored flows is not 143 considered since it may change the application intent and forwarding 144 behaviour. Furthermore the flow label may be changed en route and 145 this may also violate the measurement task. Those reasons make the 146 definition of the FlowMonID necessary for IPv6. Flow Label and 147 FlowMonID within the same packet have different scope, identify 148 different flows, and associate different uses. 150 3. Definition of the AltMark TLV 152 The desired choice is to define a new TLV for the Option and SRH 153 extension headers, carrying the data fields dedicated to the 154 alternate marking method. 156 3.1. Data Fields Format 158 The following figure shows the data fields format for enhanced 159 alternate marking TLV. This AltMark data is expected to be 160 encapsulated in the IPv6 Option (hop-by-hop or destination) and SRH 161 extension headers. 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 as defined in [RFC8321]; 191 o D: Delay flag as defined in [RFC8321]; 193 o Reserved: is reserved for further 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 So, Hop-By-Hop Options Header or Destination Options Header can be 210 used 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. 223 In summary, it is possible to list the alternative options: 225 Destination Option => measurement only by node in Destination 226 Address. 228 Hop-By-Hop Option => every router on the path with feature 229 enabled. 231 SRH TLV => every node along the SR path. 233 Destination Option + SRH => every node along the SR path. 235 Note that the SRH TLV and Destination Option + SRH can be considered 236 equivalent so in this case it may be preferred to use the SRH. 238 Both [RFC7045] and [RFC8200] do not recommend the introduction of new 239 Hop-by-Hop Options headers because nodes may be configured to ignore, 240 drop or assign to a slow processing path. But, in case of the 241 AltMark data fields described in this document, the new hop-by-hop 242 option is needed for OAM and an intermediate node can read it or not 243 but, this does not affect the packet behavior. The source node is 244 the only one that writes the hop-by-hop option to mark alternately 245 the flow, so, the performance measurement can be done for those nodes 246 configured to read this option, while the others are simply not 247 considered for the metrics. Moreover, in case of SRv6, the use of 248 SRH TLV for every node along the SR path is a good choice to 249 implement hop-by-hop measurements. 251 In addition to the previous alternatives, for legacy network it is 252 possible to mention a non-conventional application of the SRH TLV and 253 Destination Option for the hop-by-hop usage. [RFC8200] defines that 254 the nodes along a path examine and process the Hop-by-Hop Options 255 header only if HBH processing is explicitly configured. On the other 256 hand, using the SRH TLV or Destination Option for hop-by-hop action 257 would cause worse performance than Hop-By-Hop. The only motivation 258 for hiding the hop-by-hop options inside of destination options can 259 be for compatibility reasons but in general it is not recommended. 261 5. Alternate Marking Method Operation 263 [RFC8321] and [I-D.ietf-ippm-multipoint-alt-mark] describe in detail 264 the methodology. 266 6. Security Considerations 268 tbc 270 7. IANA Considerations 272 The option type should be assigned in IANA's "Destination Options and 273 Hop-by-Hop Options" registry. Also, the TLV type should be assigned 274 from Segment Routing Header TLVs Registry. 276 8. Acknowledgements 278 The authors would like to thank Bob Hinden, Ole Troan, Tom Herbert, 279 Stefano Previdi, Brian Carpenter for the precious comments and 280 suggestions. 282 9. References 284 9.1. Normative References 286 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 287 Requirement Levels", BCP 14, RFC 2119, 288 DOI 10.17487/RFC2119, March 1997, 289 . 291 9.2. Informative References 293 [I-D.fioccola-v6ops-ipv6-alt-mark] 294 Fioccola, G., Velde, G., Cociglio, M., and P. Muley, "IPv6 295 Performance Measurement with Alternate Marking Method", 296 draft-fioccola-v6ops-ipv6-alt-mark-01 (work in progress), 297 June 2018. 299 [I-D.ietf-6man-segment-routing-header] 300 Filsfils, C., Dukes, D., Previdi, S., Leddy, J., 301 Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header 302 (SRH)", draft-ietf-6man-segment-routing-header-26 (work in 303 progress), October 2019. 305 [I-D.ietf-ippm-multipoint-alt-mark] 306 Fioccola, G., Cociglio, M., Sapio, A., and R. Sisto, 307 "Multipoint Alternate Marking method for passive and 308 hybrid performance monitoring", draft-ietf-ippm- 309 multipoint-alt-mark-04 (work in progress), January 2020. 311 [I-D.song-opsawg-ifit-framework] 312 Song, H., Qin, F., Chen, H., Jin, J., and J. Shin, "In- 313 situ Flow Information Telemetry", draft-song-opsawg-ifit- 314 framework-10 (work in progress), December 2019. 316 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 317 Architecture", RFC 4291, DOI 10.17487/RFC4291, February 318 2006, . 320 [RFC7045] Carpenter, B. and S. Jiang, "Transmission and Processing 321 of IPv6 Extension Headers", RFC 7045, 322 DOI 10.17487/RFC7045, December 2013, 323 . 325 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 326 (IPv6) Specification", STD 86, RFC 8200, 327 DOI 10.17487/RFC8200, July 2017, 328 . 330 [RFC8321] Fioccola, G., Ed., Capello, A., Cociglio, M., Castaldelli, 331 L., Chen, M., Zheng, L., Mirsky, G., and T. Mizrahi, 332 "Alternate-Marking Method for Passive and Hybrid 333 Performance Monitoring", RFC 8321, DOI 10.17487/RFC8321, 334 January 2018, . 336 Authors' Addresses 338 Giuseppe Fioccola 339 Huawei 340 Riesstrasse, 25 341 Munich 80992 342 Germany 344 Email: giuseppe.fioccola@huawei.com 346 Tianran Zhou 347 Huawei 348 156 Beiqing Rd. 349 Beijing 100095 350 China 352 Email: zhoutianran@huawei.com 354 Mauro Cociglio 355 Telecom Italia 356 Via Reiss Romoli, 274 357 Torino 10148 358 Italy 360 Email: mauro.cociglio@telecomitalia.it 362 Fengwei Qin 363 China Mobile 364 32 Xuanwumenxi Ave. 365 Beijing 100032 366 China 368 Email: qinfengwei@chinamobile.com