idnits 2.17.1 draft-mirsky-ippm-hybrid-two-step-11.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (8 July 2021) is 1015 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Downref: Normative reference to an Informational RFC: RFC 2104 == Outdated reference: A later version (-17) exists of draft-ietf-ippm-ioam-data-14 == Outdated reference: A later version (-11) exists of draft-ietf-ippm-ioam-direct-export-03 == Outdated reference: A later version (-11) exists of draft-ietf-raw-use-cases-01 == Outdated reference: A later version (-16) exists of draft-song-ippm-postcard-based-telemetry-09 -- Obsolete informational reference (is this intentional?): RFC 8321 (Obsoleted by RFC 9341) Summary: 1 error (**), 0 flaws (~~), 5 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 IPPM Working Group G. Mirsky 3 Internet-Draft ZTE Corp. 4 Intended status: Standards Track W. Lingqiang 5 Expires: 9 January 2022 G. Zhui 6 ZTE Corporation 7 H. Song 8 Futurewei Technologies 9 8 July 2021 11 Hybrid Two-Step Performance Measurement Method 12 draft-mirsky-ippm-hybrid-two-step-11 14 Abstract 16 Development of, and advancements in, automation of network operations 17 brought new requirements for measurement methodology. Among them is 18 the ability to collect instant network state as the packet being 19 processed by the networking elements along its path through the 20 domain. This document introduces a new hybrid measurement method, 21 referred to as hybrid two-step, as it separates the act of measuring 22 and/or calculating the performance metric from the act of collecting 23 and transporting network state. 25 Status of This Memo 27 This Internet-Draft is submitted in full conformance with the 28 provisions of BCP 78 and BCP 79. 30 Internet-Drafts are working documents of the Internet Engineering 31 Task Force (IETF). Note that other groups may also distribute 32 working documents as Internet-Drafts. The list of current Internet- 33 Drafts is at https://datatracker.ietf.org/drafts/current/. 35 Internet-Drafts are draft documents valid for a maximum of six months 36 and may be updated, replaced, or obsoleted by other documents at any 37 time. It is inappropriate to use Internet-Drafts as reference 38 material or to cite them other than as "work in progress." 40 This Internet-Draft will expire on 9 January 2022. 42 Copyright Notice 44 Copyright (c) 2021 IETF Trust and the persons identified as the 45 document authors. All rights reserved. 47 This document is subject to BCP 78 and the IETF Trust's Legal 48 Provisions Relating to IETF Documents (https://trustee.ietf.org/ 49 license-info) in effect on the date of publication of this document. 50 Please review these documents carefully, as they describe your rights 51 and restrictions with respect to this document. Code Components 52 extracted from this document must include Simplified BSD License text 53 as described in Section 4.e of the Trust Legal Provisions and are 54 provided without warranty as described in the Simplified BSD License. 56 Table of Contents 58 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 59 2. Conventions used in this document . . . . . . . . . . . . . . 3 60 2.1. Acronyms . . . . . . . . . . . . . . . . . . . . . . . . 3 61 2.2. Requirements Language . . . . . . . . . . . . . . . . . . 4 62 3. Problem Overview . . . . . . . . . . . . . . . . . . . . . . 4 63 4. Theory of Operation . . . . . . . . . . . . . . . . . . . . . 5 64 4.1. Operation of the HTS Ingress Node . . . . . . . . . . . . 7 65 4.2. Operation of the HTS Intermediate Node . . . . . . . . . 9 66 4.3. Operation of the HTS Egress Node . . . . . . . . . . . . 10 67 4.4. Considerations for HTS Timers . . . . . . . . . . . . . . 11 68 4.5. Deploying HTS in a Multicast Network . . . . . . . . . . 11 69 5. Authentication in HTS . . . . . . . . . . . . . . . . . . . . 12 70 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 71 6.1. IOAM Option-Type for HTS . . . . . . . . . . . . . . . . 13 72 6.2. HTS TLV Registry . . . . . . . . . . . . . . . . . . . . 13 73 6.3. HTS Sub-TLV Type Sub-registry . . . . . . . . . . . . . . 14 74 6.4. HMAC Type Sub-registry . . . . . . . . . . . . . . . . . 15 75 7. Security Considerations . . . . . . . . . . . . . . . . . . . 16 76 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 16 77 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 16 78 9.1. Normative References . . . . . . . . . . . . . . . . . . 16 79 9.2. Informative References . . . . . . . . . . . . . . . . . 17 80 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18 82 1. Introduction 84 Successful resolution of challenges of automated network operation, 85 as part of, for example, overall service orchestration or data center 86 operation, relies on a timely collection of accurate information that 87 reflects the state of network elements on an unprecedented scale. 88 Because performing the analysis and act upon the collected 89 information requires considerable computing and storage resources, 90 the network state information is unlikely to be processed by the 91 network elements themselves but will be relayed into the data storage 92 facilities, e.g., data lakes. The process of producing, collecting 93 network state information also referred to in this document as 94 network telemetry, and transporting it for post-processing should 95 work equally well with data flows or injected in the network test 96 packets. RFC 7799 [RFC7799] describes a combination of elements of 97 passive and active measurement as a hybrid measurement. 99 Several technical methods have been proposed to enable the collection 100 of network state information instantaneous to the packet processing, 101 among them [P4.INT] and [I-D.ietf-ippm-ioam-data]. The 102 instantaneous, i.e., in the data packet itself, collection of 103 telemetry information simplifies the process of attribution of 104 telemetry information to the particular monitored flow. On the other 105 hand, this collection method impacts the data packets, potentially 106 changing their treatment by the networking nodes. Also, the amount 107 of information the instantaneous method collects might be incomplete 108 because of the limited space it can be allotted. Other proposals 109 defined methods to collect telemetry information in a separate packet 110 from each node traversed by the monitored data flow. Examples of 111 this approach to collecting telemetry information are 112 [I-D.ietf-ippm-ioam-direct-export] and 113 [I-D.song-ippm-postcard-based-telemetry]. These methods allow data 114 collection from any arbitrary path and avoid directly impacting data 115 packets. On the other hand, the correlation of data and the 116 monitored flow requires that each packet with telemetry information 117 also includes characteristic information about the monitored flow. 119 This document introduces Hybrid Two-Step (HTS) as a new method of 120 telemetry collection that improvers accuracy of a measurement by 121 separating the act of measuring or calculating the performance metric 122 from the collecting and transporting this information while 123 minimizing the overhead of the generated load in a network. HTS 124 method extends the two-step mode of Residence Time Measurement (RTM) 125 defined in [RFC8169] to on-path network state collection and 126 transport. HTS allows the collection of telemetry information from 127 any arbitrary path, does not change data packets of the monitored 128 flow and makes the process of attribution of telemetry to the data 129 flow simple. 131 2. Conventions used in this document 133 2.1. Acronyms 135 RTM Residence Time Measurement 137 ECMP Equal Cost Multipath 139 MTU Maximum Transmission Unit 141 HTS Hybrid Two-Step 142 HMAC Hashed Message Authentication Code 144 Network telemetry - the process of collecting and reporting of 145 network state 147 2.2. Requirements Language 149 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 150 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 151 "OPTIONAL" in this document are to be interpreted as described in BCP 152 14 [RFC2119] [RFC8174] when, and only when, they appear in all 153 capitals, as shown here. 155 3. Problem Overview 157 Performance measurements are meant to provide data that characterize 158 conditions experienced by traffic flows in the network and possibly 159 trigger operational changes (e.g., re-route of flows, or changes in 160 resource allocations). Modifications to a network are determined 161 based on the performance metric information available when a change 162 is to be made. The correctness of this determination is based on the 163 quality of the collected metrics data. The quality of collected 164 measurement data is defined by: 166 * the resolution and accuracy of each measurement; 168 * predictability of both the time at which each measurement is made 169 and the timeliness of measurement collection data delivery for 170 use. 172 Consider the case of delay measurement that relies on collecting time 173 of packet arrival at the ingress interface and time of the packet 174 transmission at the egress interface. The method includes recording 175 a local clock value on receiving the first octet of an affected 176 message at the device ingress, and again recording the clock value on 177 transmitting the first byte of the same message at the device egress. 178 In this ideal case, the difference between the two recorded clock 179 times corresponds to the time that the message spent in traversing 180 the device. In practice, the time recorded can differ from the ideal 181 case by any fixed amount. A correction can be applied to compute the 182 same time difference taking into account the known fixed time 183 associated with the actual measurement. In this way, the resulting 184 time difference reflects any variable delay associated with queuing. 186 Depending on the implementation, it may be a challenge to compute the 187 difference between message arrival and departure times and - on the 188 fly - add the necessary residence time information to the same 189 message. And that task may become even more challenging if the 190 packet is encrypted. Recording the departure of a packet time in the 191 same packet may be decremental to the accuracy of the measurement 192 because the departure time includes the variable time component (such 193 as that associated with buffering and queuing of the packet). A 194 similar problem may lower the quality of, for example, information 195 that characterizes utilization of the egress interface. If unable to 196 obtain the data consistently, without variable delays for additional 197 processing, information may not accurately reflect the egress 198 interface state. To mitigate this problem [RFC8169] defined an RTM 199 two-step mode. 201 Another challenge associated with methods that collect network state 202 information into the actual data packet is the risk to exceed the 203 Maximum Transmission Unit (MTU) size on the path, especially if the 204 packet traverses overlay domains or VPNs. Since the fragmentation is 205 not available at the transport network, operators may have to reduce 206 MTU size advertised to the client layer or risk missing network state 207 data for the part, most probably the latter part, of the path. 209 In some networks, for example, wireless that are in the scope of 210 [I-D.ietf-raw-use-cases], it is beneficial to collect the telemetry, 211 including the calculated performance metrics, that reflects 212 conditions experienced by the monitored flow at a node, other than 213 the egress. For example, a head-end can optimize path selection 214 based on the compounded information that reflects network conditions, 215 resource utilization. This mode is referred to as the upstream 216 collection and the other - downstream collection to differentiate 217 between two modes of telemetry collection.. 219 4. Theory of Operation 221 The HTS method consists of two phases: 223 * performing a measurement and/or obtaining network state 224 information on a node; 226 * collecting and transporting the measurement and/or the telemetry 227 information. 229 HTS may use an HTS Trigger carried in a data packet or a specially 230 constructed test packet. For example, an HTS Trigger could be a 231 packet that has IOAM Option-Type set to the "IOAM Hybrid Two-Step 232 Option-Type" value (TBA1) allocated by IANA (see Section 6.1). The 233 HTS Trigger also includes IOAM Namespace-ID and IOAM-Trace-Type 234 information [I-D.ietf-ippm-ioam-data]. A packet in the flow to which 235 the Alternate-Marking method [RFC8321] is applied can be used as an 236 HTS Trigger. The nature of the HTS Trigger is a transport network 237 layer-specific, and its description is outside the scope of this 238 document. The packet that includes the HTS Trigger in this document 239 is also referred to as the trigger packet. 241 The HTS method uses the HTS Follow-up packet, referred to as the 242 follow-up packet, to collect measurement and network state data from 243 the nodes. The node that creates the HTS Trigger also generates the 244 HTS Follow-up packet. In some use cases, e.g., when HTS is used to 245 collect the telemetry, including performance metrics, calculated 246 based on a series of measurements, an HTS follow-up packet can be 247 originated without using the HTS Trigger. The follow-up packet 248 contains characteristic information sufficient for participating HTS 249 nodes to associate it with the monitored data flow. The 250 characteristic information can be obtained using the information of 251 the trigger packet or constructed by a node that originates the 252 follow-up packet. As the follow-up packet is expected to traverse 253 the same sequence of nodes, one element of the characteristic 254 information is the information that determines the path in the data 255 plane. For example, in a segment routing domain [RFC8402], a list of 256 segment identifiers of the trigger packet is applied to the follow-up 257 packet. And in the case of the service function chain based on the 258 Network Service Header [RFC8300], the Base Header and Service Path 259 Header of the trigger packet will be applied to the follow-up packet. 260 Also, when HTS is used to collect the telemetry information in an 261 IOAM domain, the IOAM trace option header [I-D.ietf-ippm-ioam-data] 262 of the trigger packet is applied in the follow-up packet. The 263 follow-up packet also uses the same network information used to load- 264 balance flows in equal-cost multipath (ECMP) as the trigger packet, 265 e.g., IPv6 Flow Label [RFC6437] or an entropy label [RFC6790]. The 266 exact composition of the characteristic information is specific for 267 each transport network, and its definition is outside the scope of 268 this document. 270 Only one outstanding follow-up packet MUST be on the node for the 271 given path. That means that if the node receives an HTS Trigger for 272 the flow on which it still waits for the follow-up packet to the 273 previous HTS Trigger, the node will originate the follow-up packet to 274 transport the former set of the network state data and transmit it 275 before it sends the follow-up packet with the latest collection of 276 network state information. 278 The following sections describe the operation of HTS nodes in the 279 downstream mode of collecting the telemetry information. In the 280 upstream mode, the bahavior of HTS nodes, in general, identical with 281 the exception that the HTS Trigger packet does not precede the HTS 282 Follow-up packet. 284 4.1. Operation of the HTS Ingress Node 286 A node that originates the HTS Trigger is referred to as the HTS 287 ingress node. As stated, the ingress node originates the follow-up 288 packet. The follow-up packet has the transport network encapsulation 289 identical with the trigger packet followed by the HTS shim and one or 290 more telemetry information elements encoded as Type-Length-Value 291 {TLV}. Figure 1 displays an example of the follow-up packet format. 293 0 1 2 3 294 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 1 295 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 296 | | 297 ~ Transport Network ~ 298 | Encapsulation | 299 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 300 |Ver|HTS Shim L | Flags |Sequence Number| Reserved | 301 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 302 | HTS Max Length | 303 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 304 | Telemetry Data Profile | 305 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 306 | | 307 ~ Telemetry Data TLVs ~ 308 | | 309 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 311 Figure 1: Follow-up Packet Format 313 Fields of the HTS shim are as follows: 315 Version (Ver) is the two-bits long field. It specifies the 316 version of the HTS shim format. This document defines the format 317 for the 0b00 value of the field. 319 HTS Shim Length is the six bits-long field. It defines the length 320 of the HTS shim in octets. The minimal value of the field is 321 eight octets. 323 0 324 0 1 2 3 4 5 6 7 325 +-+-+-+-+-+-+-+-+ 326 |F| Reserved | 327 +-+-+-+-+-+-+-+-+ 329 Figure 2: Flags Field Format 331 Flags is eight-bits long. The format of the Flags field displayed 332 in Figure 2. 334 - Full (F) flag MUST be set to zero by the node originating the 335 HTS follow-up packet and MUST be set to one by the node that 336 does not add its telemetry data to avoid exceeding MTU size. 338 - The node originating the follow-up packet MUST zero the 339 Reserved field and ignore it on the receipt. 341 Sequence Number is one octet-long field. The zero-based value of 342 the field reflects the place of the HTS follow-up packet in the 343 sequence of the HTS follow-up packets that originated in response 344 to the same HTS trigger. The ingress node MUST set the value of 345 the field to zero. 347 Reserved is one octet-long field. It MUST be zeroed on 348 transmission and ignored on recepit. 350 HTS Max Length is four octet-long field. The value of th HTS Max 351 Length field indicates the maximum length of the HTS Follow-up 352 packet in octets. An operator MUST be able to configure the HTS 353 Max Length field's value. The value SHOULD be set equal to the 354 path MTU. 356 Telemetry Data Profile is the optional variable-length field of 357 bit-size flags. Each flag indicates the requested type of 358 telemetry data to be collected at each HTS node. The increment of 359 the field is four bytes with a minimum length of zero. For 360 example, IOAM-Trace-Type information defined in 361 [I-D.ietf-ippm-ioam-data] can be used in the Telemetry Data 362 Profile field. 364 0 1 2 3 365 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 1 366 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 367 | Type | Reserved | Length | 368 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 369 ~ Value ~ 370 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 371 Figure 3: Telemetry Data TLV Format 373 Telemetry Data TLV is a variable-length field. Multiple TLVs MAY 374 be placed in an HTS packet. Additional TLVs may be enclosed 375 within a given TLV, subject to the semantics of the (outer) TLV in 376 question. Figure 3 presents the format of a Telemetry Data TLV, 377 where fields are defined as the following: 379 - Type - a one-octet-long field that characterizes the 380 interpretation of the Value field. 382 - Reserved - one-octet-long field. 384 - Length - two-octet-long field equal to the length of the Value 385 field in octets. 387 - Value - a variable-length field. The value of the Type field 388 determines its interpretation and encoding. IOAM data fields, 389 defined in [I-D.ietf-ippm-ioam-data], MAY be carried in the 390 Value field. 392 All multibyte fields defined in this specification are in network 393 byte order. 395 4.2. Operation of the HTS Intermediate Node 397 Upon receiving the trigger packet, the HTS intermediate node MUST: 399 * copy the transport information; 401 * start the HTS Follow-up Timer for the obtained flow; 403 * transmit the trigger packet. 405 Upon receiving the follow-up packet, the HTS intermediate node MUST: 407 1. verify that the matching transport information exists and the 408 Full flag is cleared, then stop the associated HTS Follow-up 409 Timer; 411 2. otherwise, transmit the received packet. Proceed to Step 8; 413 3. collect telemetry data requested in the Telemetry Data Profile 414 field or defined by the local HTS policy; 416 4. if adding the collected telemetry would not exceed HTS Max Length 417 field's value, then append data as a new Telemetry Data TLV and 418 transmit the follow-up packet. Proceed to Step 8; 420 5. otherwise, set the value of the Full flag to one, copy the 421 transport information from the received follow-up packet and 422 transmit it accordingly. Proceed to Step 8; 424 6. originate the new follow-up packet using the transport 425 information copied from the received follow-up packet. The value 426 of the Sequence Number field in the HTS shim MUST be set to the 427 value of the field in the received follow-up packet incremented 428 by one; 430 7. copy collected telemetry data into the first Telemetry Data TLV's 431 Value field and then transmit the packet; 433 8. processing completed. 435 If the HTS Follow-up Timer expires, the intermediate node MUST: 437 * originate the follow-up packet using transport information 438 associated with the expired timer; 440 * initialize the HTS shim by setting the Version field's value to 441 0b00 and Sequence Number field to 0. Values of HTS Shim Length 442 and Telemetry Data Profile fields MAY be set according to the 443 local policy. 445 * copy telemetry information into Telemetry Data TLV's Value field 446 and transmit the packet. 448 If the intermediate node receives a "late" follow-up packet, i.e., a 449 packet to which the node has no associated HTS Follow-up timer, the 450 node MUST forward the "late" packet. 452 4.3. Operation of the HTS Egress Node 454 Upon receiving the trigger packet, the HTS egress node MUST: 456 * copy the transport information; 458 * start the HTS Collection timer for the obtained flow. 460 When the egress node receives the follow-up packet for the known 461 flow, i.e., the flow to which the Collection timer is running, the 462 node for each of Telemetry Data TLVs MUST: 464 * if HTS is used in the authenticated mode, verify the 465 authentication of the Telemetry Data TLV using the Authentication 466 sub-TLV (see Section 5); 468 * copy telemetry information from the Value field; 470 * restart the corresponding Collection timer. 472 When the Collection timer expires, the egress relays the collected 473 telemetry information for processing and analysis to a local or 474 remote agent. 476 4.4. Considerations for HTS Timers 478 This specification defines two timers - HTS Follow-up and HTS 479 Collection. For the particular flow, there MUST be no more than one 480 HTS Trigger, values of HTS timers bounded by the rate of the trigger 481 generation for that flow. 483 4.5. Deploying HTS in a Multicast Network 485 Previous sections discussed the operation of HTS in a unicast 486 network. Multicast services are important, and the ability to 487 collect telemetry information is invaluable in delivering a high 488 quality of experience. While the replication of data packets is 489 necessary, replication of HTS follow-up packets is not. Replication 490 of multicast data packets down a multicast tree may be set based on 491 multicast routing information or explicit information included in the 492 special header, as, for example, in Bit-Indexed Explicit Replication 493 [RFC8296]. A replicating node processes the HTS packet as defined 494 below: 496 * the first transmitted multicast packet MUST be followed by the 497 received corresponding HTS packet as described in Section 4.2; 499 * each consecutively transmitted copy of the original multicast 500 packet MUST be followed by the new HTS packet originated by the 501 replicating node that acts as an intermediate HTS node when the 502 HTS Follow-up timer expired. 504 As a result, there are no duplicate copies of Telemetry Data TLV for 505 the same pair of ingress and egress interfaces. At the same time, 506 all ingress/egress pairs traversed by the given multicast packet 507 reflected in their respective Telemetry Data TLV. Consequently, a 508 centralized controller would reconstruct and analyze the state of the 509 particular multicast distribution tree based on HTS packets collected 510 from egress nodes. 512 5. Authentication in HTS 514 Telemetry information may be used to drive network operation, closing 515 the control loop for self-driving, self-healing networks. Thus it is 516 critical to provide a mechanism to protect the telemetry information 517 collected using the HTS method. This document defines an optional 518 authentication of a Telemetry Data TLV that protects the collected 519 information's integrity. 521 The format of the Authentication sub-TLV is displayed in Figure 4. 523 0 1 2 3 524 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 1 525 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 526 |Authentic. Type| HMAC Type | Length | 527 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 528 | | 529 | Digest | 530 | | 531 | | 532 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 534 Figure 4: HMAC sub-TLV 536 where fields are defined as follows: 538 * Authentication Type - is a one-octet-long field, value TBA2 539 allocated by IANA Section 6.2. 541 * Length - two-octet-long field, set equal to the length of the 542 Digest field in octets. 544 * HMAC Type - is a one-octet-long field that identifies the type of 545 the HMAC and the length of the digest and the length of the digest 546 according to the HTS HMAC Type sub-registry (see Section 6.4). 548 * Digest - is a variable-length field that carries HMAC digest of 549 the text that includes the encompassing TLV. 551 This specification defines the use of HMAC-SHA-256 truncated to 128 552 bits ([RFC4868]) in HTS. Future specifications may define the use in 553 HTS of more advanced cryptographic algorithms or the use of digest of 554 a different length. HMAC is calculated as defined in [RFC2104] over 555 text as the concatenation of the Sequence Number field of the follow- 556 up packet (see Figure 1) and the preceding data collected in the 557 Telemetry Data TLV. The digest then MUST be truncated to 128 bits 558 and written into the Digest field. Distribution and management of 559 shared keys are outside the scope of this document. In the HTS 560 authenticated mode, the Authentication sub-TLV MUST be present in 561 each Telemetry Data TLV. HMAC MUST be verified before using any data 562 in the included Telemetry Data TLV. If HMAC verification fails, the 563 system MUST stop processing corresponding Telemetry Data TLV and 564 notify an operator. Specification of the notification mechanism is 565 outside the scope of this document. 567 6. IANA Considerations 569 6.1. IOAM Option-Type for HTS 571 The IOAM Option-Type registry is requested in 572 [I-D.ietf-ippm-ioam-data]. IANA is requested to allocate a new code 573 point as listed in Table 1. 575 +=======+==================================+===============+ 576 | Value | Description | Reference | 577 +=======+==================================+===============+ 578 | TBA1 | IOAM Hybrid Two-Step Option-Type | This document | 579 +-------+----------------------------------+---------------+ 581 Table 1: IOAM Option-Type for HTS 583 6.2. HTS TLV Registry 585 IANA is requested to create the HTS TLV Type registry. All code 586 points in the range 1 through 175 in this registry shall be allocated 587 according to the "IETF Review" procedure specified in [RFC8126]. 588 Code points in the range 176 through 239 in this registry shall be 589 allocated according to the "First Come First Served" procedure 590 specified in [RFC8126]. The remaining code points are allocated 591 according to Table 2: 593 +===========+==============+===============+ 594 | Value | Description | Reference | 595 +===========+==============+===============+ 596 | 0 | Reserved | This document | 597 +-----------+--------------+---------------+ 598 | 1- 175 | Unassigned | This document | 599 +-----------+--------------+---------------+ 600 | 176 - 239 | Unassigned | This document | 601 +-----------+--------------+---------------+ 602 | 240 - 251 | Experimental | This document | 603 +-----------+--------------+---------------+ 604 | 252 - 254 | Private Use | This document | 605 +-----------+--------------+---------------+ 606 | 255 | Reserved | This document | 607 +-----------+--------------+---------------+ 609 Table 2: HTS TLV Type Registry 611 6.3. HTS Sub-TLV Type Sub-registry 613 IANA is requested to create the HTS sub-TLV Type sub-registry as part 614 of the HTS TLV Type registry. All code points in the range 1 through 615 175 in this registry shall be allocated according to the "IETF 616 Review" procedure specified in [RFC8126]. Code points in the range 617 176 through 239 in this registry shall be allocated according to the 618 "First Come First Served" procedure specified in [RFC8126]. The 619 remaining code points are allocated according to Table 3: 621 +===========+==============+===============+ 622 | Value | Description | Reference | 623 +===========+==============+===============+ 624 | 0 | Reserved | This document | 625 +-----------+--------------+---------------+ 626 | 1- 175 | Unassigned | This document | 627 +-----------+--------------+---------------+ 628 | 176 - 239 | Unassigned | This document | 629 +-----------+--------------+---------------+ 630 | 240 - 251 | Experimental | This document | 631 +-----------+--------------+---------------+ 632 | 252 - 254 | Private Use | This document | 633 +-----------+--------------+---------------+ 634 | 255 | Reserved | This document | 635 +-----------+--------------+---------------+ 637 Table 3: HTS Sub-TLV Type Sub-registry 639 This document defines the following new values in the IETF Review 640 range of the HTS sub-TLV Type sub-registry: 642 +=======+=============+==========+===============+ 643 | Value | Description | TLV Used | Reference | 644 +=======+=============+==========+===============+ 645 | TBA2 | HMAC | Any | This document | 646 +-------+-------------+----------+---------------+ 648 Table 4: HTS sub-TLV Types 650 6.4. HMAC Type Sub-registry 652 IANA is requested to create the HMAC Type sub-registry as part of the 653 HTS TLV Type registry. All code points in the range 1 through 127 in 654 this registry shall be allocated according to the "IETF Review" 655 procedure specified in [RFC8126]. Code points in the range 128 656 through 239 in this registry shall be allocated according to the 657 "First Come First Served" procedure specified in [RFC8126]. The 658 remaining code points are allocated according to Table 5: 660 +===========+==============+===============+ 661 | Value | Description | Reference | 662 +===========+==============+===============+ 663 | 0 | Reserved | This document | 664 +-----------+--------------+---------------+ 665 | 1- 127 | Unassigned | This document | 666 +-----------+--------------+---------------+ 667 | 128 - 239 | Unassigned | This document | 668 +-----------+--------------+---------------+ 669 | 240 - 249 | Experimental | This document | 670 +-----------+--------------+---------------+ 671 | 250 - 254 | Private Use | This document | 672 +-----------+--------------+---------------+ 673 | 255 | Reserved | This document | 674 +-----------+--------------+---------------+ 676 Table 5: HMAC Type Sub-registry 678 This document defines the following new values in the HMAC Type sub- 679 registry: 681 +=======+=============================+===============+ 682 | Value | Description | Reference | 683 +=======+=============================+===============+ 684 | 1 | HMAC-SHA-256 16 octets long | This document | 685 +-------+-----------------------------+---------------+ 687 Table 6: HMAC Types 689 7. Security Considerations 691 Nodes that practice the HTS method are presumed to share a trust 692 model that depends on the existence of a trusted relationship among 693 nodes. This is necessary as these nodes are expected to correctly 694 modify the specific content of the data in the follow-up packet, and 695 the degree to which HTS measurement is useful for network operation 696 depends on this ability. In practice, this means either 697 confidentiality or integrity protection cannot cover those portions 698 of messages that contain the network state data. Though there are 699 methods that make it possible in theory to provide either or both 700 such protections and still allow for intermediate nodes to make 701 detectable yet authenticated modifications, such methods do not seem 702 practical at present, particularly for protocols that used to measure 703 latency and/or jitter. 705 This document defines the use of authentication (Section 5) to 706 protect the integrity of the telemetry information collected using 707 the HTS method. Privacy protection can be achieved by, for example, 708 sharing the IPsec tunnel with a data flow that generates information 709 that is collected using HTS. 711 While it is possible for a supposed compromised node to intercept and 712 modify the network state information in the follow-up packet; this is 713 an issue that exists for nodes in general - for all data that to be 714 carried over the particular networking technology - and is therefore 715 the basis for an additional presumed trust model associated with an 716 existing network. 718 8. Acknowledgments 720 Authors express their gratitude and appreciation to Joel Halpern for 721 the most helpful and insightful discussion on the applicability of 722 HTS in a Service Function Chaining domain. 724 9. References 726 9.1. Normative References 728 [RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed- 729 Hashing for Message Authentication", RFC 2104, 730 DOI 10.17487/RFC2104, February 1997, 731 . 733 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 734 Requirement Levels", BCP 14, RFC 2119, 735 DOI 10.17487/RFC2119, March 1997, 736 . 738 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 739 Writing an IANA Considerations Section in RFCs", BCP 26, 740 RFC 8126, DOI 10.17487/RFC8126, June 2017, 741 . 743 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 744 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 745 May 2017, . 747 9.2. Informative References 749 [I-D.ietf-ippm-ioam-data] 750 Brockners, F., Bhandari, S., and T. Mizrahi, "Data Fields 751 for In-situ OAM", Work in Progress, Internet-Draft, draft- 752 ietf-ippm-ioam-data-14, 24 June 2021, 753 . 756 [I-D.ietf-ippm-ioam-direct-export] 757 Song, H., Gafni, B., Zhou, T., Li, Z., Brockners, F., 758 Bhandari, S., Sivakolundu, R., and T. Mizrahi, "In-situ 759 OAM Direct Exporting", Work in Progress, Internet-Draft, 760 draft-ietf-ippm-ioam-direct-export-03, 17 February 2021, 761 . 764 [I-D.ietf-raw-use-cases] 765 Papadopoulos, G. Z., Thubert, P., Theoleyre, F., and C. J. 766 Bernardos, "RAW use cases", Work in Progress, Internet- 767 Draft, draft-ietf-raw-use-cases-01, 21 February 2021, 768 . 771 [I-D.song-ippm-postcard-based-telemetry] 772 Song, H., Mirsky, G., Filsfils, C., Abdelsalam, A., Zhou, 773 T., Li, Z., Shin, J., and K. Lee, "Postcard-based On-Path 774 Flow Data Telemetry using Packet Marking", Work in 775 Progress, Internet-Draft, draft-song-ippm-postcard-based- 776 telemetry-09, 19 February 2021, 777 . 780 [P4.INT] "In-band Network Telemetry (INT)", P4.org Specification, 781 October 2017. 783 [RFC4868] Kelly, S. and S. Frankel, "Using HMAC-SHA-256, HMAC-SHA- 784 384, and HMAC-SHA-512 with IPsec", RFC 4868, 785 DOI 10.17487/RFC4868, May 2007, 786 . 788 [RFC6437] Amante, S., Carpenter, B., Jiang, S., and J. Rajahalme, 789 "IPv6 Flow Label Specification", RFC 6437, 790 DOI 10.17487/RFC6437, November 2011, 791 . 793 [RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and 794 L. Yong, "The Use of Entropy Labels in MPLS Forwarding", 795 RFC 6790, DOI 10.17487/RFC6790, November 2012, 796 . 798 [RFC7799] Morton, A., "Active and Passive Metrics and Methods (with 799 Hybrid Types In-Between)", RFC 7799, DOI 10.17487/RFC7799, 800 May 2016, . 802 [RFC8169] Mirsky, G., Ruffini, S., Gray, E., Drake, J., Bryant, S., 803 and A. Vainshtein, "Residence Time Measurement in MPLS 804 Networks", RFC 8169, DOI 10.17487/RFC8169, May 2017, 805 . 807 [RFC8296] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., 808 Tantsura, J., Aldrin, S., and I. Meilik, "Encapsulation 809 for Bit Index Explicit Replication (BIER) in MPLS and Non- 810 MPLS Networks", RFC 8296, DOI 10.17487/RFC8296, January 811 2018, . 813 [RFC8300] Quinn, P., Ed., Elzur, U., Ed., and C. Pignataro, Ed., 814 "Network Service Header (NSH)", RFC 8300, 815 DOI 10.17487/RFC8300, January 2018, 816 . 818 [RFC8321] Fioccola, G., Ed., Capello, A., Cociglio, M., Castaldelli, 819 L., Chen, M., Zheng, L., Mirsky, G., and T. Mizrahi, 820 "Alternate-Marking Method for Passive and Hybrid 821 Performance Monitoring", RFC 8321, DOI 10.17487/RFC8321, 822 January 2018, . 824 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., 825 Decraene, B., Litkowski, S., and R. Shakir, "Segment 826 Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, 827 July 2018, . 829 Authors' Addresses 830 Greg Mirsky 831 ZTE Corp. 833 Email: gregimirsky@gmail.com, gregory.mirsky@ztetx.com 835 Wang Lingqiang 836 ZTE Corporation 837 No 19 ,East Huayuan Road 838 Beijing 840 Phone: +86 10 82963945 841 Email: wang.lingqiang@zte.com.cn 843 Guo Zhui 844 ZTE Corporation 845 No 19 ,East Huayuan Road 846 Beijing 848 Phone: +86 10 82963945 849 Email: guo.zhui@zte.com.cn 851 Haoyu Song 852 Futurewei Technologies 853 2330 Central Expressway 854 Santa Clara, 855 United States of America 857 Email: hsong@futurewei.com