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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: May 6, 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 November 3, 2019 16 Segment Routing Header encapsulation for In-situ OAM Data 17 draft-ali-spring-ioam-srv6-02 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 https://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 This Internet-Draft will expire on May 6, 2020. 46 Copyright Notice 48 Copyright (c) 2019 IETF Trust and the persons identified as the 49 document authors. All rights reserved. 51 This document is subject to BCP 78 and the IETF Trust's Legal 52 Provisions Relating to IETF Documents 53 (https://trustee.ietf.org/license-info) in effect on the date of 54 publication of this document. Please review these documents 55 carefully, as they describe your rights and restrictions with respect 56 to this document. Code Components extracted from this document must 57 include Simplified BSD License text as described in Section 4.e of 58 the Trust Legal Provisions and are provided without warranty as 59 described in the Simplified BSD License. 61 Table of Contents 63 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2 64 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3 65 2.1. Requirement Language . . . . . . . . . . . . . . . . . . . 3 66 2.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 3 67 3. OAM Metadata Piggybacked in Data Packets . . . . . . . . .. . 4 68 3.1 IOAM Data Field Encapsulation in SRH . . . . . . . . . . . . 4 69 4. Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . 5 70 4.1. Ingress Node . . . . . . . . . . . . . . . . . . . . . . . 5 71 4.2. SR Segment Endpoint Node . . . . . . . . . . . . . . . . . 5 72 4.3. Egress Node . . . . . . . . . . . . . . . . . . . . . . . 6 73 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 74 6. Security Considerations . . . . . . . . . . . . . . . . . . . 6 75 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6 76 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 77 8.1. Normative References . . . . . . . . . . . . . . . . . . . 7 78 8.2. Informative References . . . . . . . . . . . . . . . . . . 7 79 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 81 1. Introduction 83 OAM and PM information from the SR endpoints can be piggybacked in 84 the data packet. The OAM and PM information piggybacking in the data 85 packets is also known as In-situ OAM (IOAM). IOAM records 86 OAM information within the packet while the packet traverses a 87 particular network domain. The term "in-situ" refers to the fact 88 that the IOAM data fields are added to the data packets rather than 89 being sent within probe packets specifically dedicated to OAM. 91 This document defines how IOAM data fields are transported as part of 92 the Segment Routing with IPv6 data plane (SRv6) header 93 [I-D.6man-segment-routing-header]. 95 The IOAM data fields carried are defined in 96 [I-D.ietf-ippm-ioam-data], and can be used for various use-cases 97 including Performance Measurement (PM) and Proof-of-Transit (PoT). 99 2. Conventions 101 2.1. Requirement Language 103 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 104 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 105 document are to be interpreted as described in [RFC2119] [RFC8174] 106 when, and only when, they appear in all capitals, as shown here. 108 2.2. Abbreviations 110 Abbreviations used in this document: 112 IOAM In-situ Operations, Administration, and Maintenance 114 OAM Operations, Administration, and Maintenance 116 PM Performance Measurement 118 PoT Proof-of-Transit 120 SR Segment Routing 122 SRH SRv6 Header 124 SRv6 Segment Routing with IPv6 Data plane 126 3. OAM Metadata Piggybacked in Data Packets 128 OAM and PM information from the SR endpoints can be piggybacked in 129 the data packet. The OAM and PM information piggybacking in the data 130 packets is also known as In-situ OAM (IOAM). This section describes 131 iOAM functionality in SRv6 network. 133 The IOAM data is carried in SRH.TLV. This enables the IOAM mechanism 134 to build on the network programmability capability of SRv6. Specifically, 135 the ability for an SRv6 endpoint to determine whether to 136 process or ignore some specific SRH TLVs is based on the SID 137 function. This enables collection of the IOAM information hardware friendly 138 based on the intermediate endpoint capability. The nodes that are not 139 capable of supporting the IOAM functionality does not have to look or 140 process SRH TLV (i.e., such nodes can simply ignore the SRH IOAM 141 TLV). This also enable collection of IOAM data only from segment endpoint. 143 3.1 IOAM Data Field Encapsulation in SRH 145 The SRv6 encapsulation header (SRH) is defined in [I-D.ietf-6man- 146 segment-routing-header]. IOAM data fields are carried in the SRH, 147 using a single pre-allocated SRH TLV. The different IOAM data fields 148 defined in [I-D.ietf-ippm-ioam-data] are added as sub-TLVs. 150 0 1 2 3 151 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 1 152 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 153 | SRH-TLV-Type | LEN | RESERVED | 154 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+ 155 | IOAM-Type | IOAM HDR LEN | RESERVED | | 156 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ I 157 ! | O 158 ! | A 159 ~ IOAM Option and Data Space ~ M 160 | | | 161 | | | 162 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+ 163 | | 164 | | 165 | Payload + Padding (L2/L3/...) | 166 | | 168 | | 169 | | 170 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 172 Figure 1: IOAM data encapsulation in SRH 174 SRH-TLV-Type: IOAM TLV Type for SRH is defined as TBA1. 176 The fields related to the encapsulation of IOAM data fields in the 177 SRH are defined as follows: 179 IOAM-Type: 8-bit field defining the IOAM Option type, as defined in 180 Section 7.2 of [I-D.ietf-ippm-ioam-data]. 182 IOAM HDR LEN: 8-bit unsigned integer. Length of the IOAM HDR in 183 4-octet units. 185 RESERVED: 8-bit reserved field MUST be set to zero upon transmission 186 and ignored upon receipt. 188 IOAM Option and Data Space: IOAM option header and data is present 189 as defined by the IOAM-Type field, and is defined in Section 4 of 190 [I-D.ietf-ippm-ioam-data]. 192 4. Procedure 194 This section summarizes the procedure for IOAM data encapsulation in 195 SRv6 SRH. The SR nodes implementing the IOAM functionality follows 196 the MTU and other considerations outlined in 197 [I-D.6man-extension-header-insertion]. 199 4.1. Ingress Node 201 As part of the SRH encapsulation, the ingress node of an SR domain or 202 an SR Policy [I-D.ietf-spring-segment-routing-policy] MAY add the 203 IOAM TLV in the SRH of the data packet. If an ingress node supports 204 IOAM functionality and, based on a local configuration, wants to 205 collect IOAM data, it adds IOAM TLV in the SRH. Based on the size of 206 the segment list (SL), the ingress node preallocates space in the 207 IOAM TLV. 209 If IOAM data from the last node in the segment-list (Egress node) is 210 desired, the ingress uses an Ultimate Segment Pop (USP) SID 211 advertised by the Egress node. 213 The ingress node MAY also insert the IOAM data about the local 214 information in the IOAM TLV in the SRH at index 0 of the preallocated 215 IOAM TLV. 217 4.2. Intermediate SR Segment Endpoint Node 219 The SR segment endpoint node is any node receiving an IPv6 packet 220 where the destination address of that packet is a local SID. As part 221 of the SR Header processing as described in [I-D.ietf-6man-segment- 222 routing-header] and [I-D.ietf-spring-srv6-network-programming], the 223 SR Segment Endpoint node performs the following IOAM operations. 225 If an intermediate SR segment endpoint node is not capable of 226 processing IOAM TLV, it simply ignores it. I.e., it does not have to 227 look or process SRH TLV. 229 If an intermediate SR segment endpoint node is capable of processing 230 IOAM TLV and the local SID supports IOAM data recording, it checks if 231 any SRH TLV is present in the packet using procedures defined in [I- 232 D.ietf-6man-segment-routing-header]. If the node finds IOAM TLV in 233 the SRH it finds the local index at which it is expected to record 234 the IOAM data. The local index is found using the SRH.SL field. The 235 node records the IOAM data at the desired preallocated space. 237 4.3. Egress Node 239 The Egress node is the last node in the segment-list of the SRH. 240 When IOAM data from the Egress node is desired, a USP SID advertised 241 by the Egress node is used by the Ingress node. 243 The processing of IOAM TLV at the Egress node is similar to the 244 processing of IOAM TLV at the SR Segment Endpoint Node. The only 245 difference is that the Egress node may telemeter the IOAM data to an 246 external entity. 248 5. IANA Considerations 250 IANA is requested to allocate a mutable SRH TLV Type for IOAM TLV data fields 251 under registry name "Segment Routing Header TLVs" requested by [I- 252 D.6man-segment-routing-header]. 254 +--------------+--------------------------+---------------+ 255 | SRH TLV Type | Description | Reference | 256 +--------------+--------------------------+---------------+ 257 | TBA1 Greater | TLV for IOAM Data Fields | This document | 258 | than 128 | | | 259 +--------------+--------------------------+---------------+ 261 6. Security Considerations 263 The security considerations of SRv6 are discussed in 264 [I-D.spring-srv6-network-programming] and 265 [I-D.6man-segment-routing-header], and the security considerations of 266 IOAM in general are discussed in [I-D.ietf-ippm-ioam-data]. 268 IOAM is considered a "per domain" feature, where one or several 269 operators decide on leveraging and configuring IOAM according to 270 their needs. Still, operators need to properly secure the IOAM 271 domain to avoid malicious configuration and use, which could include 272 injecting malicious IOAM packets into a domain. 274 7. Acknowledgements 276 The authors would like to thank Shwetha Bhandari and Vengada Prasad 277 Govindan for the discussions on IOAM. 279 8. References 281 8.1. Normative References 283 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 284 Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/ 285 RFC2119, March 1997. 287 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 288 2119 Key Words", RFC 8174, May 2017. 290 [I-D.spring-srv6-network-programming] Filsfils, C. et al. "SRv6 291 Network Programming", 292 draft-filsfils-spring-srv6-network-programming, work in 293 progress. 295 [I-D.6man-segment-routing-header] Previdi, S., Filsfils, C. et al, 296 "IPv6 Segment Routing Header (SRH)", 297 draft-ietf-6man-segment-routing-header, work in progress. 299 [I-D.ietf-ippm-ioam-data] Brockners, F., Bhandari, S., Pignataro, 300 C., Gredler, H., Leddy, J., Youell, S., Mizrahi, T., 301 Mozes, D., Lapukhov, P., Chang, R., and Bernier, D., "Data 302 Fields for In-situ OAM", draft-ietf-ippm-ioam-data, work 303 in progress. 305 [I-D.spring-segment-routing-policy] Filsfils, C., et al., "Segment 306 Routing Policy Architecture", 307 draft-ietf-spring-segment-routing-policy, work in 308 progress. 310 8.2. Informative References 312 [I-D.6man-extension-header-insertion] D. Voyer, et al., "Insertion 313 of IPv6 Segment Routing Headers in a Controlled Domain", 314 draft-voyer-6man-extension-header-insertion, work in 315 progress. 317 Authors' Addresses 319 Zafar Ali 320 Cisco Systems, Inc. 322 Email: zali@cisco.com 324 Rakesh Gandhi 325 Cisco Systems, Inc. 326 Canada 328 Email: rgandhi@cisco.com 330 Clarence Filsfils 331 Cisco Systems, Inc. 332 Belgium 334 Email: cf@cisco.com 336 Frank Brockners 337 Cisco Systems, Inc. 338 Germany 340 Email: fbrockne@cisco.com 342 Nagendra Kumar Nainar 343 Cisco Systems, Inc. 345 Email: naikumar@cisco.com 347 Carlos Pignataro 348 Cisco Systems, Inc. 350 Email: cpignata@cisco.com 352 Cheng Li 353 Huawei 355 Email: chengli13@huawei.com 357 Mach(Guoyi) Chen 358 Huawei 360 Email: mach.chen@huawei.com 362 Gaurav Dawra 363 LinkedIn 365 Email: gdawra.ietf@gmail.com