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Bhandari, Ed. 4 Intended status: Standards Track Cisco 5 Expires: March 14, 2020 September 11, 2019 7 Network Service Header (NSH) Encapsulation for In-situ OAM (IOAM) Data 8 draft-ietf-sfc-ioam-nsh-02 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 March 14, 2020. 35 Copyright Notice 37 Copyright (c) 2019 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 . . . . . . . . . . . . 5 58 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 59 6. Security Considerations . . . . . . . . . . . . . . . . . . . 6 60 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 61 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 6 62 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 63 9.1. Normative References . . . . . . . . . . . . . . . . . . 8 64 9.2. Informative References . . . . . . . . . . . . . . . . . 8 65 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 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 defined in [I-D.ietf-ippm-ioam-data]. In an administrative 106 domain where IOAM is used, insertion of the IOAM header in NSH is 107 enabled at the NSH tunnel endpoints, which also serve as IOAM 108 encapsulating/decapsulating nodes by means of configuration. 110 0 1 2 3 111 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 1 112 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+ 113 |Ver|O|U| TTL | Length |U|U|U|U|MD Type| NP = TBD_IOAM | | 114 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ N 115 | Service Path Identifier | Service Index | S 116 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ H 117 | ... | | 118 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+ 119 | IOAM-Type | IOAM HDR len | Reserved | Next Protocol | | 120 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ I 121 ! | O 122 ! | A 123 ~ IOAM Option and Data Space ~ M 124 | | | 125 | | | 126 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+ 127 | | 128 | | 129 | Payload + Padding (L2/L3/ESP/...) | 130 | | 131 | | 132 | | 133 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 135 The NSH header and fields are defined in [RFC8300]. The "NSH Next 136 Protocol" value (referred to as "NP" in the diagram above) is 137 TBD_IOAM. 139 The IOAM related fields in NSH are defined as follows: 141 IOAM-Type: 8-bit field defining the IOAM Option type, as defined 142 in Section 7.2 of [I-D.ietf-ippm-ioam-data]. 144 IOAM HDR Len: 8 bit Length field contains the length of the IOAM 145 header in 4-octet units. 147 Reserved bits: Reserved bits are present for future use. The 148 reserved bits MUST be set to 0x0 upon transmission and ignored 149 upon receipt. 151 Next Protocol: 8-bit unsigned integer that determines the type of 152 header following IOAM protocol. The semantics of this field 153 are identical to the Next Protocol field in [RFC8300]. 155 IOAM Option and Data Space: IOAM option header and data is 156 present as specified by the IOAM-Type field, and is defined in 157 Section 4 of [I-D.ietf-ippm-ioam-data]. 159 Multiple IOAM options MAY be included within the NSH encapsulation. 160 For example, if a NSH encapsulation contains two IOAM options before 161 a data payload, the Next Protocol field of the first IOAM option will 162 contain the value of TBD_IOAM, while the Next Protocol field of the 163 second IOAM option will contain the "NSH Next Protocol" number 164 indicating the type of the data payload. 166 4. Considerations 168 This section summarizes a set of considerations on the overall 169 approach taken for IOAM data encapsulation in NSH, as well as 170 deployment considerations. 172 4.1. Discussion of the encapsulation approach 174 This section is to support the working group discussion in selecting 175 the most appropriate approach for encapsulating IOAM data fields in 176 NSH. 178 An encapsulation of IOAM data fields in NSH should be friendly to an 179 implementation in both hardware as well as software forwarders and 180 support a wide range of deployment cases, including large networks 181 that desire to leverage multiple IOAM data fields at the same time. 183 Hardware and software friendly implementation: Hardware forwarders 184 benefit from an encapsulation that minimizes iterative look-ups of 185 fields within the packet: Any operation which looks up the value 186 of a field within the packet, based on which another lookup is 187 performed, consumes additional gates and time in an implementation 188 - both of which are desired to be kept to a minimum. This means 189 that flat TLV structures are to be preferred over nested TLV 190 structures. IOAM data fields are grouped into three option 191 categories: Trace, proof-of-transit, and edge-to-edge. Each of 192 these three options defines a TLV structure. A hardware-friendly 193 encapsulation approach avoids grouping these three option 194 categories into yet another TLV structure, but would rather carry 195 the options as a serial sequence. 197 Total length of the IOAM data fields: The total length of IOAM 198 data can grow quite large in case multiple different IOAM data 199 fields are used and large path-lengths need to be considered. If 200 for example an operator would consider using the IOAM trace option 201 and capture node-id, app_data, egress/ingress interface-id, 202 timestamp seconds, timestamps nanoseconds at every hop, then a 203 total of 20 octets would be added to the packet at every hop. In 204 case this particular deployment would have a maximum path length 205 of 15 hops in the IOAM domain, then a maximum of 300 octets of 206 IOAM data were to be encapsulated in the packet. 208 Different approaches for encapsulating IOAM data fields in NSH could 209 be considered: 211 1. Encapsulation of IOAM data fields as "NSH MD Type 2" (see 212 [RFC8300], Section 2.5). Each IOAM data field option (trace, 213 proof-of-transit, and edge-to-edge) would be specified by a type, 214 with the different IOAM data fields being TLVs within this the 215 particular option type. NSH MD Type 2 offers support for 216 variable length meta-data. The length field is 6-bits, resulting 217 in a maximum of 256 (2^6 x 4) octets. 219 2. Encapsulation of IOAM data fields using the "Next Protocol" 220 field. Each IOAM data field option (trace, proof-of-transit, and 221 edge-to-edge) would be specified by its own "next protocol". 223 3. Encapsulation of IOAM data fields using the "Next Protocol" 224 field. A single NSH protocol type code point would be allocated 225 for IOAM. A "sub-type" field would then specify what IOAM 226 options type (trace, proof-of-transit, edge-to-edge) is carried. 228 The third option has been chosen here. This option avoids the 229 additional layer of TLV nesting that the use of NSH MD Type 2 would 230 result in. In addition, this option does not constrain IOAM data to 231 a maximum of 256 octets, thus allowing support for very large 232 deployments. 234 4.2. IOAM and the use of the NSH O-bit 236 [RFC8300] defines an "O bit" for OAM packets. Per [RFC8300] the O 237 bit must be set for OAM packets and must not be set for non-OAM 238 packets. Packets with IOAM data included MUST follow this 239 definition, i.e. the O bit MUST NOT be set for regular customer 240 traffic which also carries IOAM data and the O bit MUST be set for 241 OAM packets which carry only IOAM data without any regular data 242 payload. 244 5. IANA Considerations 246 IANA is requested to allocate protocol numbers for the following "NSH 247 Next Protocol" related to IOAM: 249 +---------------+-------------+---------------+ 250 | Next Protocol | Description | Reference | 251 +---------------+-------------+---------------+ 252 | x | TBD_IOAM | This document | 253 +---------------+-------------+---------------+ 255 6. Security Considerations 257 IOAM is considered a "per domain" feature, where one or several 258 operators decide on leveraging and configuring IOAM according to 259 their needs. Still, operators need to properly secure the IOAM 260 domain to avoid malicious configuration and use, which could include 261 injecting malicious IOAM packets into a domain. 263 7. Acknowledgements 265 The authors would like to thank Eric Vyncke, Nalini Elkins, Srihari 266 Raghavan, Ranganathan T S, Karthik Babu Harichandra Babu, Akshaya 267 Nadahalli, Stefano Previdi, Hemant Singh, Erik Nordmark, LJ Wobker, 268 and Andrew Yourtchenko for the comments and advice. 270 8. Contributors 272 In addition to editors listed on the title page, the following people 273 have contributed to this document: 275 Vengada Prasad Govindan 276 Cisco Systems, Inc. 277 Email: venggovi@cisco.com 279 Carlos Pignataro 280 Cisco Systems, Inc. 281 7200-11 Kit Creek Road 282 Research Triangle Park, NC 27709 283 United States 284 Email: cpignata@cisco.com 285 Hannes Gredler 286 RtBrick Inc. 287 Email: hannes@rtbrick.com 289 John Leddy 290 Email: john@leddy.net 292 Stephen Youell 293 JP Morgan Chase 294 25 Bank Street 295 London E14 5JP 296 United Kingdom 297 Email: stephen.youell@jpmorgan.com 299 Tal Mizrahi 300 Huawei Network.IO Innovation Lab 301 Israel 302 Email: tal.mizrahi.phd@gmail.com 304 David Mozes 305 Email: mosesster@gmail.com 307 Petr Lapukhov 308 Facebook 309 1 Hacker Way 310 Menlo Park, CA 94025 311 US 312 Email: petr@fb.com 314 Remy Chang 315 Barefoot Networks 316 2185 Park Boulevard 317 Palo Alto, CA 94306 318 US 320 9. References 321 9.1. Normative References 323 [I-D.ietf-ippm-ioam-data] 324 Brockners, F., Bhandari, S., Pignataro, C., Gredler, H., 325 Leddy, J., Youell, S., Mizrahi, T., Mozes, D., Lapukhov, 326 P., Chang, R., daniel.bernier@bell.ca, d., and J. Lemon, 327 "Data Fields for In-situ OAM", draft-ietf-ippm-ioam- 328 data-06 (work in progress), July 2019. 330 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 331 Requirement Levels", BCP 14, RFC 2119, 332 DOI 10.17487/RFC2119, March 1997, 333 . 335 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 336 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 337 May 2017, . 339 [RFC8300] Quinn, P., Ed., Elzur, U., Ed., and C. Pignataro, Ed., 340 "Network Service Header (NSH)", RFC 8300, 341 DOI 10.17487/RFC8300, January 2018, 342 . 344 9.2. Informative References 346 [FD.io] "Fast Data Project: FD.io", . 348 [RFC7665] Halpern, J., Ed. and C. Pignataro, Ed., "Service Function 349 Chaining (SFC) Architecture", RFC 7665, 350 DOI 10.17487/RFC7665, October 2015, 351 . 353 Authors' Addresses 355 Frank Brockners (editor) 356 Cisco Systems, Inc. 357 Hansaallee 249, 3rd Floor 358 DUESSELDORF, NORDRHEIN-WESTFALEN 40549 359 Germany 361 Email: fbrockne@cisco.com 362 Shwetha Bhandari (editor) 363 Cisco Systems, Inc. 364 Cessna Business Park, Sarjapura Marathalli Outer Ring Road 365 Bangalore, KARNATAKA 560 087 366 India 368 Email: shwethab@cisco.com