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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 RTGWG Working Group G. Mirsky 3 Internet-Draft ZTE Corp. 4 Intended status: Informational December 29, 2018 5 Expires: July 2, 2019 7 Identification of Overlay Operations, Administration, and Maintenance 8 (OAM) 9 draft-mirsky-rtgwg-oam-identify-01 11 Abstract 13 This document analyzes how the presence of Operations, 14 Administration, and Maintenance (OAM) control command and/or special 15 data is identified in some overlay networks and an impact on the 16 choice of identification may have on OAM functionality. 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 July 2, 2019. 35 Copyright Notice 37 Copyright (c) 2018 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 used in this document . . . . . . . . . . . . . . 2 54 2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 2 55 2.2. Keywords . . . . . . . . . . . . . . . . . . . . . . . . 3 56 3. Overlay Network Encapsulations . . . . . . . . . . . . . . . 3 57 3.1. Encapsulations with Meta-data . . . . . . . . . . . . . . 3 58 3.1.1. Available Solutions . . . . . . . . . . . . . . . . . 5 59 3.2. Fixed-size Encapsulations . . . . . . . . . . . . . . . . 5 60 3.3. Source Information Availability . . . . . . . . . . . . . 6 61 3.4. On-path OAM . . . . . . . . . . . . . . . . . . . . . . . 6 62 4. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . 7 63 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 64 6. Security Considerations . . . . . . . . . . . . . . . . . . . 7 65 7. Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . 7 66 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 67 8.1. Normative References . . . . . . . . . . . . . . . . . . 7 68 8.2. Informational References . . . . . . . . . . . . . . . . 8 69 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 10 71 1. Introduction 73 Operations, Administration, and Maintenance (OAM) protocols are used 74 to detect, localize defects in the network, and monitor network 75 performance. Some OAM functions, e.g., failure detection, work in 76 the network proactively, while others, e.g., defect localization, 77 usually performed on-demand. These tasks achieved by a combination 78 of active, passive, and hybrid OAM methods, as defined in [RFC7799]. 80 This document analyzes how the presence of Operations, 81 Administration, and Maintenance (OAM) control command and/or special 82 data, i.e., OAM packet, is identified in some overlay networks, and 83 an impact the choice of identification may have on OAM functionality 84 of active and hybrid OAM methods for the respective overlay network 85 encapsulation. 87 2. Conventions used in this document 89 2.1. Terminology 91 AMM Alternate Marking method 93 BIER Bit Indexed Explicit Replication 95 DetNet Deterministic Networks 97 GUE Generic UDP Encapsulation 98 HTS Hybrid Two-step 100 NSH Network Service Header 102 NVO3 Network Virtualization Overlays 104 OAM Operations, Administration and Maintenance 106 SFC Service Function Chaining 108 TLV Type-Length-Value 110 VXLAN-GPE Generic Protocol Extension for VXLAN 112 Underlay Network or Underlay Layer: The network that provides 113 connectivity between the DetNet nodes. MPLS network that provides 114 LSP connectivity between DetNet nodes is an example of an underlay 115 layer. 117 2.2. Keywords 119 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 120 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 121 "OPTIONAL" in this document are to be interpreted as described in BCP 122 14 [RFC2119] [RFC8174] when, and only when, they appear in all 123 capitals, as shown here. 125 3. Overlay Network Encapsulations 127 New overlay network encapsulations analyzed in two groups: 129 o encapsulations that support optional meta-data; 131 o fixed-size encapsulations. 133 3.1. Encapsulations with Meta-data 135 Number of the new encapsulation protocols (e.g., Geneve 136 [I-D.ietf-nvo3-geneve], GUE [I-D.ietf-intarea-gue], and SFC NSH 137 [RFC8300]) support use of Type-Length-Value (TLV) encoding to include 138 optional information into the header. The identification of OAM in 139 these protocols is as the following: 141 Geneve: 143 O (1 bit): OAM packet. This packet contains a control message 144 instead of a data payload. Endpoints MUST NOT forward the 145 payload and transit devices MUST NOT attempt to interpret or 146 process it. Since these are infrequent control messages, it is 147 RECOMMENDED that endpoints direct these packets to a high 148 priority control queue (for example, to direct the packet to a 149 general purpose CPU from a forwarding ASIC or to separate out 150 control traffic on a NIC). Transit devices MUST NOT alter 151 forwarding behavior on the basis of this bit, such as ECMP link 152 selection. 154 GUE: 156 C-bit provides the separate namespace to carry formatted data 157 that are implicitly addressed to the decapsulator to monitor or 158 control the state or behavior of a tunnel. The payload is 159 interpreted as a control message with type specified in the 160 proto/ctype field. The format and contents of the control 161 message are indicated by the type and can be variable length. 163 SFC NSH: 165 O bit: Setting this bit indicates an OAM packet. 167 Common between Geneve and NSH is the use of the dedicated flag to 168 identify the OAM packet and, at the same time, the presence of the 169 field that identifies the protocol of the payload that immediately 170 follows after the encapsulation header. [RFC8393] points that if the 171 value of that field interpreted as none, i.e., no payload follows the 172 header, then OAM may be included in TLVs, thus creating an active OAM 173 packet. The problem with this mechanism to support active OAM 174 methods may be a limitation of the size of data that can be included 175 in a TLV. For example, the maximum size of data in an NSH Meta-data 176 Type 2, as defined in section 2.5.1 [RFC8300], is 512 octets. The 177 maximum length of data in Geneve Option, per section 3.5 178 [I-D.ietf-nvo3-geneve], is 128 octets. Thus, using one TLV as active 179 OAM packet, would not allow creating test packets of larger size, 180 which is useful when measuring packet loss and latency with synthetic 181 traffic as part of service activation procedure. 183 [I-D.ietf-sfc-oam-framework] suggests that the O bit used to identify 184 OAM packet and the Next Protocol field identifies the OAM function: 186 While the presence of OAM marker in the overlay header (e.g., O 187 bit in the NSH header) indicates it as OAM packet, it is not 188 sufficient to signal for which OAM function the packet is 189 intended. 191 At the same time, some of in-situ OAM proposals, e.g., 192 [I-D.ietf-sfc-ioam-nsh], suggest using TLV to communicate hybrid OAM 193 commands and data. The proposed resolution of using the combination 194 of O bit and the Next Protocol field: 196 ... the O bit MUST NOT be set for regular customer traffic which 197 also carries IOAM data and the O bit MUST be set for OAM packets 198 which carry only IOAM data without any regular data payload. 200 implies that the O bit only identifies the active OAM packet and not 201 set when hybrid OAM methods used. 203 3.1.1. Available Solutions 205 One of the possible solutions for encapsulations with meta-data has 206 been specified in [I-D.ietf-sfc-multi-layer-oam]: 208 To identify the active OAM message the value on the Next Protocol 209 field MUST be set to Active SFC OAM. The rules of interpreting the 210 values of O bit and the Next Protocol field are as follows: 212 o O bit set, and the Next Protocol value is not one of identifying 213 active or hybrid OAM protocol (per [RFC7799] definitions), e.g., 214 defined in this specification Active SFC OAM - a Fixed-Length 215 Context Header or Variable-Length Context Header(s) contain OAM 216 command or data. and the type of payload determined by the Next 217 Protocol field; 219 o O bit set, and the Next Protocol value is one of identifying 220 active or hybrid OAM protocol - the payload that immediately 221 follows SFC NSH contains OAM command or data; 223 o O bit is clear - no OAM in a Fixed-Length Context Header or 224 Variable-Length Context Header(s) and the payload determined by 225 the value of the Next Protocol field; 227 o O bit is clear and the Next Protocol value is one of identifying 228 active or hybrid OAM protocol MUST be identified and reported as 229 the erroneous combination. An implementation MAY have control to 230 enable processing of the OAM payload. 232 3.2. Fixed-size Encapsulations 234 Number of the new encapsulation protocols (e.g., VXLAN-GPE 235 [I-D.ietf-nvo3-vxlan-gpe], BIER [RFC8296]) suse fixed-size header. 236 The identification of OAM in these protocols is as the following: 238 VXLAN-GPE: 240 OAM Flag Bit (O bit): The O bit is set to indicate that the 241 packet is an OAM packet. 243 BIER: 245 OAM packet identified by the value of the Next Protocol field. 246 IANA BIER Next Protocol Identifiers registry includes the 247 identifier for OAM (5). 249 The use of a combination of OAM Flag Bit and the Next Protocol field 250 in VXLAN-GPE requires clarification of the header interpretation when 251 the OAM Flag Bit is set, and the value of the Next Protocol field is 252 one of defined in section 3.2 of [I-D.ietf-nvo3-vxlan-gpe]. 254 BIER encapsulation, defined in [RFC8296], identifies OAM message 255 immediately following the BIER header by the value of the Next 256 Protocol field. 258 3.3. Source Information Availability 260 Availability of the packet originator's source information is 261 required for active two-way OAM, e.g., echo request/reply. In cases 262 when the underlay network is IPv4/IPv6 the source information will be 263 derived from the underlay. But when using MPLS underlay network 264 encapsulation of an active OAM packet have to follow specific rules: 266 o if available, use Sender ID in the overlay domain (example BFIR ID 267 in BIER [RFC8296]; 269 o use IP/UDP encapsulation of an OAM packet in the overlay (similar 270 to Section 4.3 [RFC8029]). 272 3.4. On-path OAM 274 In addition to active methods, OAM toolset may include methods that 275 don't use specially constructed and injected in the network test 276 packets. [RFC7799] defines OAM methods that are neither entirely 277 active nor passive but are a combination of both as hybrid methods. 279 One of the examples of the hybrid OAM methods, in-situ OAM, mentioned 280 in Section 3.1. Another example, Alternate Marking method (AMM) 281 [RFC8321], enables on-path OAM functions, e.g., delay and loss 282 measurements, using the data traffic. Because AMM impact on the 283 network can be minimized, measured metrics can be correlated to the 284 network conditions experienced by the specific service. Of all 285 listed in Section 3, BIER allocated the field that may be used for 286 AMM, as discussed in [I-D.ietf-bier-pmmm-oam]. Applicability of AMM 287 to other overlay protocols, i.e., SFC NSH discussed in 289 [I-D.mirsky-sfc-pmamm], Geneve [I-D.fmm-nvo3-pm-alt-mark], and in 290 IPv6 networks [I-D.fioccola-v6ops-ipv6-alt-mark], been actively 291 discussed. 293 Hybrid Two-step (HTS), defined in [I-D.mirsky-ippm-hybrid-two-step], 294 provides on-path collection and transport of the telemetry 295 information. HTS enables accurate and consistent measurements by 296 separating the measurement action from the transporting data while 297 ensuring that the follow-up packet that carries the telemetry 298 information does follow the data packet that had triggered the 299 measurement. 301 4. Conclusions 303 OAM control commands and data may be present as part of the overlay 304 encapsulation header or as a payload that follows the overlay network 305 header. The recommendations: 307 o OAM in the overlay header, if supported by the overlay network, 308 identified by the dedicated flag. Use of this method as active 309 OAM is possible, but functionality is limited. 311 o OAM that follows the overlay header identified as payload type, 312 e.g., by the value of the Next Protocol field. 314 5. IANA Considerations 316 This document does not propose any IANA consideration. This section 317 may be removed. 319 6. Security Considerations 321 This document lists the OAM requirements for a DetNet domain and does 322 not raise any security concerns or issues in addition to ones common 323 to networking. 325 7. Acknowledgment 327 TBD 329 8. References 331 8.1. Normative References 333 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 334 Requirement Levels", BCP 14, RFC 2119, 335 DOI 10.17487/RFC2119, March 1997, 336 . 338 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 339 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 340 May 2017, . 342 8.2. Informational References 344 [I-D.fioccola-v6ops-ipv6-alt-mark] 345 Fioccola, G., Velde, G., Cociglio, M., and P. Muley, "IPv6 346 Performance Measurement with Alternate Marking Method", 347 draft-fioccola-v6ops-ipv6-alt-mark-01 (work in progress), 348 June 2018. 350 [I-D.fmm-nvo3-pm-alt-mark] 351 Fioccola, G., Mirsky, G., and T. Mizrahi, "Performance 352 Measurement (PM) with Alternate Marking in Network 353 Virtualization Overlays (NVO3)", draft-fmm-nvo3-pm-alt- 354 mark-03 (work in progress), October 2018. 356 [I-D.ietf-bier-pmmm-oam] 357 Mirsky, G., Zheng, L., Chen, M., and G. Fioccola, 358 "Performance Measurement (PM) with Marking Method in Bit 359 Index Explicit Replication (BIER) Layer", draft-ietf-bier- 360 pmmm-oam-05 (work in progress), December 2018. 362 [I-D.ietf-intarea-gue] 363 Herbert, T., Yong, L., and O. Zia, "Generic UDP 364 Encapsulation", draft-ietf-intarea-gue-06 (work in 365 progress), August 2018. 367 [I-D.ietf-nvo3-geneve] 368 Gross, J., Ganga, I., and T. Sridhar, "Geneve: Generic 369 Network Virtualization Encapsulation", draft-ietf- 370 nvo3-geneve-08 (work in progress), October 2018. 372 [I-D.ietf-nvo3-vxlan-gpe] 373 Maino, F., Kreeger, L., and U. Elzur, "Generic Protocol 374 Extension for VXLAN", draft-ietf-nvo3-vxlan-gpe-06 (work 375 in progress), April 2018. 377 [I-D.ietf-sfc-ioam-nsh] 378 Brockners, F., Bhandari, S., Govindan, V., Pignataro, C., 379 Gredler, H., Leddy, J., Youell, S., Mizrahi, T., Mozes, 380 D., Lapukhov, P., and R. Chang, "NSH Encapsulation for In- 381 situ OAM Data", draft-ietf-sfc-ioam-nsh-00 (work in 382 progress), May 2018. 384 [I-D.ietf-sfc-multi-layer-oam] 385 Mirsky, G., Meng, W., Khasnabish, B., and C. Wang, "Active 386 OAM for Service Function Chains in Networks", draft-ietf- 387 sfc-multi-layer-oam-00 (work in progress), November 2018. 389 [I-D.ietf-sfc-oam-framework] 390 Aldrin, S., Pignataro, C., Kumar, N., Akiya, N., Krishnan, 391 R., and A. Ghanwani, "Service Function Chaining (SFC) 392 Operation, Administration and Maintenance (OAM) 393 Framework", draft-ietf-sfc-oam-framework-05 (work in 394 progress), September 2018. 396 [I-D.mirsky-ippm-hybrid-two-step] 397 Mirsky, G., Lingqiang, W., and G. Zhui, "Hybrid Two-Step 398 Performance Measurement Method", draft-mirsky-ippm-hybrid- 399 two-step-02 (work in progress), October 2018. 401 [I-D.mirsky-sfc-pmamm] 402 Mirsky, G., Fioccola, G., and T. Mizrahi, "Performance 403 Measurement (PM) with Alternate Marking Method in Service 404 Function Chaining (SFC) Domain", draft-mirsky-sfc-pmamm-06 405 (work in progress), October 2018. 407 [RFC7799] Morton, A., "Active and Passive Metrics and Methods (with 408 Hybrid Types In-Between)", RFC 7799, DOI 10.17487/RFC7799, 409 May 2016, . 411 [RFC8029] Kompella, K., Swallow, G., Pignataro, C., Ed., Kumar, N., 412 Aldrin, S., and M. Chen, "Detecting Multiprotocol Label 413 Switched (MPLS) Data-Plane Failures", RFC 8029, 414 DOI 10.17487/RFC8029, March 2017, 415 . 417 [RFC8296] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., 418 Tantsura, J., Aldrin, S., and I. Meilik, "Encapsulation 419 for Bit Index Explicit Replication (BIER) in MPLS and Non- 420 MPLS Networks", RFC 8296, DOI 10.17487/RFC8296, January 421 2018, . 423 [RFC8300] Quinn, P., Ed., Elzur, U., Ed., and C. Pignataro, Ed., 424 "Network Service Header (NSH)", RFC 8300, 425 DOI 10.17487/RFC8300, January 2018, 426 . 428 [RFC8321] Fioccola, G., Ed., Capello, A., Cociglio, M., Castaldelli, 429 L., Chen, M., Zheng, L., Mirsky, G., and T. Mizrahi, 430 "Alternate-Marking Method for Passive and Hybrid 431 Performance Monitoring", RFC 8321, DOI 10.17487/RFC8321, 432 January 2018, . 434 [RFC8393] Farrel, A. and J. Drake, "Operating the Network Service 435 Header (NSH) with Next Protocol "None"", RFC 8393, 436 DOI 10.17487/RFC8393, May 2018, 437 . 439 Author's Address 441 Greg Mirsky 442 ZTE Corp. 444 Email: gregimirsky@gmail.com