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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 SPRING Working Group Z. Ali 3 Internet-Draft R. Gandhi 4 Intended status: Standards Track C. Filsfils 5 Expires: January 9, 2020 F. Brockners 6 N. Nainar 7 C. Pignataro 8 Cisco Systems, Inc. 9 C. Li 10 M. Chen 11 Huawei 12 G. Dawra 13 LinkedIn 14 July 8, 2019 16 Segment Routing Header encapsulation for In-situ OAM Data 17 draft-ali-spring-ioam-srv6-01 19 Abstract 21 OAM and PM information from the SR endpoints can be piggybacked in 22 the data packet. The OAM and PM information piggybacking in the data 23 packets is also known as In-situ OAM (IOAM). IOAM records 24 operational and telemetry information in the data packet while the 25 packet traverses a path between two points in the network. This 26 document defines how IOAM data fields are transported as part of the 27 Segment Routing with IPv6 data plane (SRv6) header. 29 Status of This Memo 31 This Internet-Draft is submitted in full conformance with the 32 provisions of BCP 78 and BCP 79. 34 Internet-Drafts are working documents of the Internet Engineering 35 Task Force (IETF). Note that other groups may also distribute 36 working documents as Internet-Drafts. The list of current Internet- 37 Drafts is at http://datatracker.ietf.org/drafts/current/. 39 Internet-Drafts are draft documents valid for a maximum of six months 40 and may be updated, replaced, or obsoleted by other documents at any 41 time. It is inappropriate to use Internet-Drafts as reference 42 material or to cite them other than as "work in progress." 44 Copyright Notice 46 Copyright (c) 2018 IETF Trust and the persons identified as the 47 document authors. All rights reserved. 49 This document is subject to BCP 78 and the IETF Trust's Legal 50 Provisions Relating to IETF Documents 51 (http://trustee.ietf.org/license-info) in effect on the date of 52 publication of this document. Please review these documents 53 carefully, as they describe your rights and restrictions with respect 54 to this document. Code Components extracted from this document must 55 include Simplified BSD License text as described in Section 4.e of 56 the Trust Legal Provisions and are provided without warranty as 57 described in the Simplified BSD License. 59 Table of Contents 61 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2 62 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3 63 2.1. Requirement Language . . . . . . . . . . . . . . . . . . . 3 64 2.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 3 65 3. OAM Metadata Piggybacked in Data Packets . . . . . . . . .. . 4 66 3.1 IOAM Data Field Encapsulation in SRH . . . . . . . . . . . . 4 67 4. Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . 5 68 4.1. Ingress Node . . . . . . . . . . . . . . . . . . . . . . . 5 69 4.2. SR Segment Endpoint Node . . . . . . . . . . . . . . . . . 5 70 4.3. Egress Node . . . . . . . . . . . . . . . . . . . . . . . 6 71 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 72 6. Security Considerations . . . . . . . . . . . . . . . . . . . 6 73 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6 74 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 75 8.1. Normative References . . . . . . . . . . . . . . . . . . . 7 76 8.2. Informative References . . . . . . . . . . . . . . . . . . 7 77 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 79 1. Introduction 81 OAM and PM information from the SR endpoints can be piggybacked in 82 the data packet. The OAM and PM information piggybacking in the data 83 packets is also known as In-situ OAM (IOAM). IOAM records 84 OAM information within the packet while the packet traverses a 85 particular network domain. The term "in-situ" refers to the fact 86 that the IOAM data fields are added to the data packets rather than 87 being sent within probe packets specifically dedicated to OAM. 89 This document defines how IOAM data fields are transported as part of 90 the Segment Routing with IPv6 data plane (SRv6) header 91 [I-D.6man-segment-routing-header]. 93 The IOAM data fields carried are defined in 94 [I-D.ietf-ippm-ioam-data], and can be used for various use-cases 95 including Performance Measurement (PM) and Proof-of-Transit (PoT). 97 2. Conventions 99 2.1. Requirement Language 101 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 102 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 103 document are to be interpreted as described in [RFC2119] [RFC8174] 104 when, and only when, they appear in all capitals, as shown here. 106 2.2. Abbreviations 108 Abbreviations used in this document: 110 IOAM In-situ Operations, Administration, and Maintenance 112 OAM Operations, Administration, and Maintenance 114 PM Performance Measurement 116 PoT Proof-of-Transit 118 SR Segment Routing 120 SRH SRv6 Header 122 SRv6 Segment Routing with IPv6 Data plane 124 3. OAM Metadata Piggybacked in Data Packets 126 OAM and PM information from the SR endpoints can be piggybacked in 127 the data packet. The OAM and PM information piggybacking in the data 128 packets is also known as In-situ OAM (IOAM). This section describes 129 iOAM functionality in SRv6 network. 131 The IOAM data is carried in SRH.TLV. This enables the IOAM mechanism 132 to build on the network programmability capability of SRv6. The 133 ability for an SRv6 endpoint to determine whether to 134 process or ignore some specific SRH TLVs is based on the SID 135 function. This enables collection of the IOAM information from the 136 intermediate endpoint nodes of choice. The nodes that are not 137 capable of supporting the IOAM functionality does not have to look or 138 process SRH TLV (i.e., such nodes can simply ignore the SRH IOAM 139 TLV). 141 3.1 IOAM Data Field Encapsulation in SRH 143 The SRv6 encapsulation header (SRH) is defined in [I-D.ietf-6man- 144 segment-routing-header]. IOAM data fields are carried in the SRH, 145 using a single pre-allocated SRH TLV. The different IOAM data fields 146 defined in [I-D.ietf-ippm-ioam-data] are added as sub-TLVs. 148 0 1 2 3 149 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 1 150 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 151 | SRH-TLV-Type | LEN | RESERVED | 152 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+ 153 | IOAM-Type | IOAM HDR LEN | RESERVED | | 154 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ I 155 ! | O 156 ! | A 157 ~ IOAM Option and Data Space ~ M 158 | | | 159 | | | 160 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+ 161 | | 162 | | 163 | Payload + Padding (L2/L3/...) | 164 | | 166 | | 167 | | 168 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 170 Figure 1: IOAM data encapsulation in SRH 172 SRH-TLV-Type: IOAM TLV Type for SRH is defined as TBA1. 174 The fields related to the encapsulation of IOAM data fields in the 175 SRH are defined as follows: 177 IOAM-Type: 8-bit field defining the IOAM Option type, as defined in 178 Section 7.2 of [I-D.ietf-ippm-ioam-data]. 180 IOAM HDR LEN: 8-bit unsigned integer. Length of the IOAM HDR in 181 4-octet units. 183 RESERVED: 8-bit reserved field MUST be set to zero upon transmission 184 and ignored upon receipt. 186 IOAM Option and Data Space: IOAM option header and data is present 187 as defined by the IOAM-Type field, and is defined in Section 4 of 188 [I-D.ietf-ippm-ioam-data]. 190 4. Procedure 192 This section summarizes the procedure for IOAM data encapsulation in 193 SRv6 SRH. The SR nodes implementing the IOAM functionality follows 194 the MTU and other considerations outlined in 195 [I-D.6man-extension-header-insertion]. 197 4.1. Ingress Node 199 As part of the SRH encapsulation, the ingress node of an SR domain or 200 an SR Policy [I-D.ietf-spring-segment-routing-policy] MAY add the 201 IOAM TLV in the SRH of the data packet. If an ingress node supports 202 IOAM functionality and, based on a local configuration, wants to 203 collect IOAM data, it adds IOAM TLV in the SRH. Based on the size of 204 the segment list (SL), the ingress node preallocates space in the 205 IOAM TLV. 207 If IOAM data from the last node in the segment-list (Egress node) is 208 desired, the ingress uses an Ultimate Segment Pop (USP) SID 209 advertised by the Egress node. 211 The ingress node may also insert the IOAM data about the local 212 information in the IOAM TLV in the SRH at index 0 of the preallocated 213 IOAM TLV. 215 4.2. Intermediate SR Segment Endpoint Node 217 The SR segment endpoint node is any node receiving an IPv6 packet 218 where the destination address of that packet is a local SID. As part 219 of the SR Header processing as described in [I-D.ietf-6man-segment- 220 routing-header] and [I-D.ietf-spring-srv6-network-programming], the 221 SR Segment Endpoint node performs the following IOAM operations. 223 If an intermediate SR segment endpoint node is not capable of 224 processing IOAM TLV, it simply ignores it. I.e., it does not have to 225 look or process SRH TLV. 227 If an intermediate SR segment endpoint node is capable of processing 228 IOAM TLV and the local SID supports IOAM data recording, it checks if 229 any SRH TLV is present in the packet using procedures defined in [I- 230 D.ietf-6man-segment-routing-header]. If the node finds IOAM TLV in 231 the SRH it finds the local index at which it is expected to record 232 the IOAM data. The local index is found using the SRH.SL field. The 233 node records the IOAM data at the desired preallocated space. 235 4.3. Egress Node 237 The Egress node is the last node in the segment-list of the SRH. 238 When IOAM data from the Egress node is desired, a USP SID advertised 239 by the Egress node is used by the Ingress node. 241 The processing of IOAM TLV at the Egress node is similar to the 242 processing of IOAM TLV at the SR Segment Endpoint Node. The only 243 difference is that the Egress node may telemeter the IOAM data to an 244 external entity. 246 5. IANA Considerations 248 IANA is requested to allocate a mutable SRH TLV Type for IOAM TLV data fields 249 under registry name "Segment Routing Header TLVs" requested by [I- 250 D.6man-segment-routing-header]. 252 +--------------+--------------------------+---------------+ 253 | SRH TLV Type | Description | Reference | 254 +--------------+--------------------------+---------------+ 255 | TBA1 Greater | TLV for IOAM Data Fields | This document | 256 | than 128 | | | 257 +--------------+--------------------------+---------------+ 259 6. Security Considerations 261 The security considerations of SRv6 are discussed in 262 [I-D.spring-srv6-network-programming] and 263 [I-D.6man-segment-routing-header], and the security considerations of 264 IOAM in general are discussed in [I-D.ietf-ippm-ioam-data]. 266 IOAM is considered a "per domain" feature, where one or several 267 operators decide on leveraging and configuring IOAM according to 268 their needs. Still, operators need to properly secure the IOAM 269 domain to avoid malicious configuration and use, which could include 270 injecting malicious IOAM packets into a domain. 272 7. Acknowledgements 274 The authors would like to thank Shwetha Bhandari and Vengada Prasad 275 Govindan for the discussions on IOAM. 277 8. References 279 8.1. Normative References 281 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 282 Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/ 283 RFC2119, March 1997. 285 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 286 2119 Key Words", RFC 8174, May 2017. 288 [I-D.spring-srv6-network-programming] Filsfils, C. et al. "SRv6 289 Network Programming", 290 draft-filsfils-spring-srv6-network-programming, work in 291 progress. 293 [I-D.6man-segment-routing-header] Previdi, S., Filsfils, C. et al, 294 "IPv6 Segment Routing Header (SRH)", 295 draft-ietf-6man-segment-routing-header, work in progress. 297 [I-D.ietf-ippm-ioam-data] Brockners, F., Bhandari, S., Pignataro, 298 C., Gredler, H., Leddy, J., Youell, S., Mizrahi, T., 299 Mozes, D., Lapukhov, P., Chang, R., and Bernier, D., "Data 300 Fields for In-situ OAM", draft-ietf-ippm-ioam-data, work 301 in progress. 303 [I-D.spring-segment-routing-policy] Filsfils, C., et al., "Segment 304 Routing Policy Architecture", 305 draft-ietf-spring-segment-routing-policy, work in 306 progress. 308 8.2. Informative References 310 [I-D.6man-extension-header-insertion] D. Voyer, et al., "Insertion 311 of IPv6 Segment Routing Headers in a Controlled Domain", 312 draft-voyer-6man-extension-header-insertion, work in 313 progress. 315 Authors' Addresses 317 Zafar Ali 318 Cisco Systems, Inc. 320 Email: zali@cisco.com 322 Rakesh Gandhi 323 Cisco Systems, Inc. 324 Canada 326 Email: rgandhi@cisco.com 328 Clarence Filsfils 329 Cisco Systems, Inc. 330 Belgium 332 Email: cf@cisco.com 334 Frank Brockners 335 Cisco Systems, Inc. 336 Germany 338 Email: fbrockne@cisco.com 340 Nagendra Kumar Nainar 341 Cisco Systems, Inc. 343 Email: naikumar@cisco.com 345 Carlos Pignataro 346 Cisco Systems, Inc. 348 Email: cpignata@cisco.com 350 Cheng Li 351 Huawei 353 Email: chengli13@huawei.com 355 Mach(Guoyi) Chen 356 Huawei 358 Email: mach.chen@huawei.com 360 Gaurav Dawra 361 LinkedIn 363 Email: gdawra.ietf@gmail.com