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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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-17) exists of draft-ietf-ippm-ioam-data-09 == Outdated reference: A later version (-08) exists of draft-ietf-sfc-proof-of-transit-05 ** Downref: Normative reference to an Experimental draft: draft-ietf-sfc-proof-of-transit (ref. 'I-D.ietf-sfc-proof-of-transit') Summary: 1 error (**), 0 flaws (~~), 3 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 SFC F. Brockners, Ed. 3 Internet-Draft S. Bhandari, Ed. 4 Intended status: Standards Track Cisco 5 Expires: December 18, 2020 June 16, 2020 7 Network Service Header (NSH) Encapsulation for In-situ OAM (IOAM) Data 8 draft-ietf-sfc-ioam-nsh-04 10 Abstract 12 In-situ Operations, Administration, and Maintenance (IOAM) records 13 operational and telemetry information in the packet while the packet 14 traverses a path between two points in the network. This document 15 outlines how IOAM data fields are encapsulated in the Network Service 16 Header (NSH). 18 Status of This Memo 20 This Internet-Draft is submitted in full conformance with the 21 provisions of BCP 78 and BCP 79. 23 Internet-Drafts are working documents of the Internet Engineering 24 Task Force (IETF). Note that other groups may also distribute 25 working documents as Internet-Drafts. The list of current Internet- 26 Drafts is at https://datatracker.ietf.org/drafts/current/. 28 Internet-Drafts are draft documents valid for a maximum of six months 29 and may be updated, replaced, or obsoleted by other documents at any 30 time. It is inappropriate to use Internet-Drafts as reference 31 material or to cite them other than as "work in progress." 33 This Internet-Draft will expire on December 18, 2020. 35 Copyright Notice 37 Copyright (c) 2020 IETF Trust and the persons identified as the 38 document authors. All rights reserved. 40 This document is subject to BCP 78 and the IETF Trust's Legal 41 Provisions Relating to IETF Documents 42 (https://trustee.ietf.org/license-info) in effect on the date of 43 publication of this document. Please review these documents 44 carefully, as they describe your rights and restrictions with respect 45 to this document. Code Components extracted from this document must 46 include Simplified BSD License text as described in Section 4.e of 47 the Trust Legal Provisions and are provided without warranty as 48 described in the Simplified BSD License. 50 Table of Contents 52 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 53 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 2 54 3. IOAM data fields encapsulation in NSH . . . . . . . . . . . . 3 55 4. Considerations . . . . . . . . . . . . . . . . . . . . . . . 4 56 4.1. Discussion of the encapsulation approach . . . . . . . . 4 57 4.2. IOAM and the use of the NSH O-bit . . . . . . . . . . . . 6 58 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 59 6. Security Considerations . . . . . . . . . . . . . . . . . . . 6 60 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 61 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 6 62 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 63 9.1. Normative References . . . . . . . . . . . . . . . . . . 8 64 9.2. Informative References . . . . . . . . . . . . . . . . . 8 65 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 67 1. Introduction 69 In-situ OAM (IOAM), as defined in [I-D.ietf-ippm-ioam-data], records 70 OAM information within the packet while the packet traverses a 71 particular network domain. The term "in-situ" refers to the fact 72 that the OAM data is added to the data packets rather than is being 73 sent within packets specifically dedicated to OAM. This document 74 defines how IOAM data fields are transported as part of the Network 75 Service Header (NSH) [RFC8300] encapsulation for the Service Function 76 Chaining (SFC) [RFC7665]. The IOAM-Data-Fields are defined in 77 [I-D.ietf-ippm-ioam-data]. An implementation of IOAM which leverages 78 NSH to carry the IOAM data is available from the FD.io open source 79 software project [FD.io]. 81 2. Conventions 83 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 84 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 85 "OPTIONAL" in this document are to be interpreted as described in BCP 86 14 [RFC2119] [RFC8174] when, and only when, they appear in all 87 capitals, as shown here. 89 Abbreviations used in this document: 91 IOAM: In-situ Operations, Administration, and Maintenance 93 NSH: Network Service Header 95 OAM: Operations, Administration, and Maintenance 97 SFC: Service Function Chaining 98 TLV: Type, Length, Value 100 3. IOAM data fields encapsulation in NSH 102 The NSH is defined in [RFC8300]. IOAM-Data-Fields are carried in NSH 103 using a next protocol header which follows the NSH MD context 104 headers. An IOAM header is added containing the different IOAM-Data- 105 Fields. The IOAM-Data-Fields MUST follow the definitions in 106 [I-D.ietf-ippm-ioam-data]. If "proof-of-transit" is used in 107 conjunction with NSH, the implementation of proof of transit MUST 108 follow [I-D.ietf-sfc-proof-of-transit]. In an administrative domain 109 where IOAM is used, insertion of the IOAM header in NSH is enabled at 110 the NSH tunnel endpoints, which also serve as IOAM encapsulating/ 111 decapsulating nodes by means of configuration. 113 0 1 2 3 114 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 1 115 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+ 116 |Ver|O|U| TTL | Length |U|U|U|U|MD Type| NP = TBD_IOAM | | 117 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ N 118 | Service Path Identifier | Service Index | S 119 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ H 120 | ... | | 121 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+ 122 | IOAM-Type | IOAM HDR len | Reserved | Next Protocol | | 123 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ I 124 ! | O 125 ! | A 126 ~ IOAM Option and Data Space ~ M 127 | | | 128 | | | 129 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+ 130 | | 131 | | 132 | Payload + Padding (L2/L3/ESP/...) | 133 | | 134 | | 135 | | 136 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 138 The NSH header and fields are defined in [RFC8300]. The "NSH Next 139 Protocol" value (referred to as "NP" in the diagram above) is 140 TBD_IOAM. 142 The IOAM related fields in NSH are defined as follows: 144 IOAM-Type: 8-bit field defining the IOAM-Option-Type, as defined 145 in the IOAM Option-Type Registry (see Section 7.2 of 146 [I-D.ietf-ippm-ioam-data]). 148 IOAM HDR Len: 8 bit Length field contains the length of the IOAM 149 header in 4-octet units. 151 Reserved bits: Reserved bits are present for future use. The 152 reserved bits MUST be set to 0x0 upon transmission and ignored 153 upon receipt. 155 Next Protocol: 8-bit unsigned integer that determines the type of 156 header following IOAM. The semantics of this field are 157 identical to the Next Protocol field in [RFC8300]. 159 IOAM Option and Data Space: IOAM-Option-Type and IOAM-Data-Field 160 as specified by the IOAM-Type field are present (see Section 4 161 of [I-D.ietf-ippm-ioam-data]). 163 Multiple IOAM-Option-Types MAY be included within the NSH 164 encapsulation. For example, if a NSH encapsulation contains two 165 IOAM-Option-Types before a data payload, the Next Protocol field of 166 the first IOAM option will contain the value of TBD_IOAM, while the 167 Next Protocol field of the second IOAM-Option-Type will contain the 168 "NSH Next Protocol" number indicating the type of the data payload. 170 4. Considerations 172 This section summarizes a set of considerations on the overall 173 approach taken for IOAM data encapsulation in NSH, as well as 174 deployment considerations. 176 4.1. Discussion of the encapsulation approach 178 This section discusses several approaches for encapsulating IOAM- 179 Data-Fields in NSH and presents the rationale for the approach chosen 180 in this document. 182 An encapsulation of IOAM-Data-Fields in NSH should be friendly to an 183 implementation in both hardware as well as software forwarders and 184 support a wide range of deployment cases, including large networks 185 that desire to leverage multiple IOAM-Data-Fields at the same time. 187 Hardware and software friendly implementation: Hardware forwarders 188 benefit from an encapsulation that minimizes iterative look-ups of 189 fields within the packet: Any operation which looks up the value of a 190 field within the packet, based on which another lookup is performed, 191 consumes additional gates and time in an implementation - both of 192 which are desired to be kept to a minimum. This means that flat TLV 193 structures are to be preferred over nested TLV structures. IOAM- 194 Data-Fields are grouped into several categories, including trace, 195 proof-of-transit, and edge-to-edge. Each of these options defines a 196 TLV structure. A hardware-friendly encapsulation approach avoids 197 grouping these three option categories into yet another TLV 198 structure, but would rather carry the options as a serial sequence. 200 Total length of the IOAM-Data-Fields: The total length of IOAM-Data- 201 Fields can grow quite large in case multiple different IOAM-Data- 202 Fields are used and large path-lengths need to be considered. If for 203 example an operator would consider using the IOAM Trace Option-Type 204 and capture node-id, app_data, egress/ingress interface-id, timestamp 205 seconds, timestamps nanoseconds at every hop, then a total of 20 206 octets would be added to the packet at every hop. In case this 207 particular deployment would have a maximum path length of 15 hops in 208 the IOAM domain, then a maximum of 300 octets were to be encapsulated 209 in the packet. 211 Different approaches for encapsulating IOAM-Data-Fields in NSH could 212 be considered: 214 1. Encapsulation of IOAM-Data-Fields as "NSH MD Type 2" (see 215 [RFC8300], Section 2.5). Each IOAM-Option-Type (e.g. trace, 216 proof-of-transit, and edge-to-edge) would be specified by a type, 217 with the different IOAM-Data-Fields being TLVs within this the 218 particular option type. NSH MD Type 2 offers support for 219 variable length meta-data. The length field is 6-bits, resulting 220 in a maximum of 256 (2^6 x 4) octets. 222 2. Encapsulation of IOAM-Data-Fields using the "Next Protocol" 223 field. Each IOAM-Option-Type (e.g trace, proof-of-transit, and 224 edge-to-edge) would be specified by its own "next protocol". 226 3. Encapsulation of IOAM-Data-Fields using the "Next Protocol" 227 field. A single NSH protocol type code point would be allocated 228 for IOAM. A "sub-type" field would then specify what IOAM 229 options type (trace, proof-of-transit, edge-to-edge) is carried. 231 The third option has been chosen here. This option avoids the 232 additional layer of TLV nesting that the use of NSH MD Type 2 would 233 result in. In addition, this option does not constrain IOAM data to 234 a maximum of 256 octets, thus allowing support for very large 235 deployments. 237 4.2. IOAM and the use of the NSH O-bit 239 [RFC8300] defines an "O bit" for OAM packets. Per [RFC8300] the O 240 bit must be set for OAM packets and must not be set for non-OAM 241 packets. Packets with IOAM data included MUST follow this 242 definition, i.e. the O bit MUST NOT be set for regular customer 243 traffic which also carries IOAM data and the O bit MUST be set for 244 OAM packets which carry only IOAM data without any regular data 245 payload. 247 5. IANA Considerations 249 IANA is requested to allocate protocol numbers for the following "NSH 250 Next Protocol" related to IOAM: 252 +---------------+-------------+---------------+ 253 | Next Protocol | Description | Reference | 254 +---------------+-------------+---------------+ 255 | x | TBD_IOAM | This document | 256 +---------------+-------------+---------------+ 258 6. Security Considerations 260 IOAM is considered a "per domain" feature, where one or several 261 operators decide on leveraging and configuring IOAM according to 262 their needs. Still, operators need to properly secure the IOAM 263 domain to avoid malicious configuration and use, which could include 264 injecting malicious IOAM packets into a domain. For additional IOAM 265 related security considerations, see Section 8 in 266 [I-D.ietf-ippm-ioam-data]. For proof of transit related security 267 considerations, see Section 7 in [I-D.ietf-sfc-proof-of-transit]. 269 7. Acknowledgements 271 The authors would like to thank Eric Vyncke, Nalini Elkins, Srihari 272 Raghavan, Ranganathan T S, Karthik Babu Harichandra Babu, Akshaya 273 Nadahalli, Stefano Previdi, Hemant Singh, Erik Nordmark, LJ Wobker, 274 and Andrew Yourtchenko for the comments and advice. 276 8. Contributors 278 In addition to editors listed on the title page, the following people 279 have contributed to this document: 281 Vengada Prasad Govindan 282 Cisco Systems, Inc. 283 Email: venggovi@cisco.com 285 Carlos Pignataro 286 Cisco Systems, Inc. 287 7200-11 Kit Creek Road 288 Research Triangle Park, NC 27709 289 United States 290 Email: cpignata@cisco.com 292 Hannes Gredler 293 RtBrick Inc. 294 Email: hannes@rtbrick.com 296 John Leddy 297 Email: john@leddy.net 299 Stephen Youell 300 JP Morgan Chase 301 25 Bank Street 302 London E14 5JP 303 United Kingdom 304 Email: stephen.youell@jpmorgan.com 306 Tal Mizrahi 307 Huawei Network.IO Innovation Lab 308 Israel 309 Email: tal.mizrahi.phd@gmail.com 311 David Mozes 312 Email: mosesster@gmail.com 314 Petr Lapukhov 315 Facebook 316 1 Hacker Way 317 Menlo Park, CA 94025 318 US 319 Email: petr@fb.com 320 Remy Chang 321 Barefoot Networks 322 2185 Park Boulevard 323 Palo Alto, CA 94306 324 US 326 9. References 328 9.1. Normative References 330 [I-D.ietf-ippm-ioam-data] 331 Brockners, F., Bhandari, S., Pignataro, C., Gredler, H., 332 Leddy, J., Youell, S., Mizrahi, T., Mozes, D., Lapukhov, 333 P., remy@barefootnetworks.com, r., daniel.bernier@bell.ca, 334 d., and J. Lemon, "Data Fields for In-situ OAM", draft- 335 ietf-ippm-ioam-data-09 (work in progress), March 2020. 337 [I-D.ietf-sfc-proof-of-transit] 338 Brockners, F., Bhandari, S., Mizrahi, T., Dara, S., and S. 339 Youell, "Proof of Transit", draft-ietf-sfc-proof-of- 340 transit-05 (work in progress), May 2020. 342 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 343 Requirement Levels", BCP 14, RFC 2119, 344 DOI 10.17487/RFC2119, March 1997, 345 . 347 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 348 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 349 May 2017, . 351 [RFC8300] Quinn, P., Ed., Elzur, U., Ed., and C. Pignataro, Ed., 352 "Network Service Header (NSH)", RFC 8300, 353 DOI 10.17487/RFC8300, January 2018, 354 . 356 9.2. Informative References 358 [FD.io] "Fast Data Project: FD.io", . 360 [RFC7665] Halpern, J., Ed. and C. Pignataro, Ed., "Service Function 361 Chaining (SFC) Architecture", RFC 7665, 362 DOI 10.17487/RFC7665, October 2015, 363 . 365 Authors' Addresses 367 Frank Brockners (editor) 368 Cisco Systems, Inc. 369 Hansaallee 249, 3rd Floor 370 DUESSELDORF, NORDRHEIN-WESTFALEN 40549 371 Germany 373 Email: fbrockne@cisco.com 375 Shwetha Bhandari (editor) 376 Cisco Systems, Inc. 377 Cessna Business Park, Sarjapura Marathalli Outer Ring Road 378 Bangalore, KARNATAKA 560 087 379 India 381 Email: shwethab@cisco.com