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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) No issues found here. Summary: 0 errors (**), 0 flaws (~~), 1 warning (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group G. Mirsky 3 Internet-Draft X. Min 4 Updates: 8762 (if approved) ZTE Corp. 5 Intended status: Standards Track H. Nydell 6 Expires: December 14, 2020 Accedian Networks 7 R. Foote 8 Nokia 9 A. Masputra 10 Apple Inc. 11 E. Ruffini 12 OutSys 13 June 12, 2020 15 Simple Two-way Active Measurement Protocol Optional Extensions 16 draft-ietf-ippm-stamp-option-tlv-05 18 Abstract 20 This document describes optional extensions to Simple Two-way Active 21 Measurement Protocol (STAMP) which enable measurement performance 22 metrics in addition to ones supported by the STAMP base 23 specification. The document also defines a STAMP Test Session 24 Identifier and thus updates RFC 8762. 26 Status of This Memo 28 This Internet-Draft is submitted in full conformance with the 29 provisions of BCP 78 and BCP 79. 31 Internet-Drafts are working documents of the Internet Engineering 32 Task Force (IETF). Note that other groups may also distribute 33 working documents as Internet-Drafts. The list of current Internet- 34 Drafts is at https://datatracker.ietf.org/drafts/current/. 36 Internet-Drafts are draft documents valid for a maximum of six months 37 and may be updated, replaced, or obsoleted by other documents at any 38 time. It is inappropriate to use Internet-Drafts as reference 39 material or to cite them other than as "work in progress." 41 This Internet-Draft will expire on December 14, 2020. 43 Copyright Notice 45 Copyright (c) 2020 IETF Trust and the persons identified as the 46 document authors. All rights reserved. 48 This document is subject to BCP 78 and the IETF Trust's Legal 49 Provisions Relating to IETF Documents 50 (https://trustee.ietf.org/license-info) in effect on the date of 51 publication of this document. Please review these documents 52 carefully, as they describe your rights and restrictions with respect 53 to this document. Code Components extracted from this document must 54 include Simplified BSD License text as described in Section 4.e of 55 the Trust Legal Provisions and are provided without warranty as 56 described in the Simplified BSD License. 58 Table of Contents 60 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 61 2. Conventions used in this document . . . . . . . . . . . . . . 3 62 2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 63 2.2. Requirements Language . . . . . . . . . . . . . . . . . . 3 64 3. STAMP Test Session Identifier . . . . . . . . . . . . . . . . 4 65 4. TLV Extensions to STAMP . . . . . . . . . . . . . . . . . . . 8 66 4.1. Extra Padding TLV . . . . . . . . . . . . . . . . . . . . 9 67 4.2. Location TLV . . . . . . . . . . . . . . . . . . . . . . 10 68 4.3. Timestamp Information TLV . . . . . . . . . . . . . . . . 11 69 4.4. Class of Service TLV . . . . . . . . . . . . . . . . . . 12 70 4.5. Direct Measurement TLV . . . . . . . . . . . . . . . . . 14 71 4.6. Access Report TLV . . . . . . . . . . . . . . . . . . . . 15 72 4.7. Follow-up Telemetry TLV . . . . . . . . . . . . . . . . . 16 73 4.8. HMAC TLV . . . . . . . . . . . . . . . . . . . . . . . . 18 74 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19 75 5.1. STAMP TLV Registry . . . . . . . . . . . . . . . . . . . 19 76 5.2. Synchronization Source Sub-registry . . . . . . . . . . . 20 77 5.3. Timestamping Method Sub-registry . . . . . . . . . . . . 20 78 5.4. Return Code Sub-registry . . . . . . . . . . . . . . . . 21 79 6. Security Considerations . . . . . . . . . . . . . . . . . . . 22 80 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 22 81 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 22 82 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 22 83 9.1. Normative References . . . . . . . . . . . . . . . . . . 22 84 9.2. Informative References . . . . . . . . . . . . . . . . . 23 85 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24 87 1. Introduction 89 Simple Two-way Active Measurement Protocol (STAMP) [RFC8762] supports 90 the use of optional extensions that use Type-Length-Value (TLV) 91 encoding. Such extensions enhance the STAMP base functions, such as 92 measurement of one-way and round-trip delay, latency, packet loss, 93 and the ability to detect packet duplication and out-of- order 94 delivery of the test packets. This specification defines optional 95 STAMP extensions, their formats, and the theory of operation. Also, 96 a STAMP Test Session Identifier is defined as an update of the base 97 STAMP specification [RFC8762]. 99 2. Conventions used in this document 101 2.1. Terminology 103 STAMP - Simple Two-way Active Measurement Protocol 105 DSCP - Differentiated Services Code Point 107 ECN - Explicit Congestion Notification 109 NTP - Network Time Protocol 111 PTP - Precision Time Protocol 113 HMAC Hashed Message Authentication Code 115 TLV Type-Length-Value 117 BITS Building Integrated Timing Supply 119 SSU Synchronization Supply Unit 121 GPS Global Positioning System 123 GLONASS Global Orbiting Navigation Satellite System 125 LORAN-C Long Range Navigation System Version C 127 MBZ Must Be Zero 129 CoS Class of Service 131 PMF Performance Measurement Function 133 SSID STAMP Session Identifier 135 2.2. Requirements Language 137 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 138 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 139 "OPTIONAL" in this document are to be interpreted as described in BCP 140 14 [RFC2119] [RFC8174] when, and only when, they appear in all 141 capitals, as shown here. 143 3. STAMP Test Session Identifier 145 STAMP Session-Sender transmits test packets to STAMP Session- 146 Reflector. STAMP Session-Reflector receives Session-Sender's packet 147 and acts according to the configuration and optional control 148 information communicated in the Session-Sender's test packet. STAMP 149 defines two different test packet formats, one for packets 150 transmitted by the STAMP-Session-Sender and one for packets 151 transmitted by the STAMP-Session-Reflector. STAMP supports two 152 modes: unauthenticated and authenticated. Unauthenticated STAMP test 153 packets are compatible on the wire with unauthenticated TWAMP-Test 154 [RFC5357] packet formats. 156 By default, STAMP uses symmetrical packets, i.e., the size of the 157 packet transmitted by Session-Reflector equals the size of the packet 158 received by the Session-Reflector. 160 A STAMP Session is identified using 4-tuple (source and destination 161 IP addresses, source and destination UDP port numbers). A STAMP 162 Session-Sender MAY generate a locally unique STAMP Session Identifier 163 (SSID). SSID is two octets long non-zero unsigned integer. A 164 Session-Sender MAY use SSID to identify a STAMP test session. If 165 SSID is used, it MUST be present in each test packet of the given 166 test session. In the unauthenticated mode, SSID is located, as 167 displayed in Figure 1. 169 0 1 2 3 170 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 1 171 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 172 | Sequence Number | 173 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 174 | Timestamp | 175 | | 176 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 177 | Error Estimate | SSID | 178 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 179 | | 180 | | 181 | MBZ (28 octets) | 182 | | 183 | | 184 | | 185 | | 186 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 187 | Type | Length | 188 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 189 ~ Value ~ 190 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 192 Figure 1: An example of an extended STAMP Session-Sender test packet 193 format in unauthenticated mode 195 An implementation of STAMP Session-Reflector that supports this 196 specification SHOULD identify a STAMP Session using the SSID in 197 combination with elements of the usual 4-tuple for the session. 198 Before a test session commenced, a Session-Reflector MUST be 199 provisioned with all the elements that identify the STAMP Session. A 200 STAMP Session-Reflector MUST discard the non-matching STAMP test 201 packet(s). The means of provisioning the STAMP Session 202 identification is outside the scope of this specification. A 203 conforming implementation of STAMP Session-Reflector MUST copy the 204 SSID value from the received test packet and put it into the 205 reflected packet, as displayed in Figure 2. 207 0 1 2 3 208 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 1 209 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 210 | Sequence Number | 211 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 212 | Timestamp | 213 | | 214 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 215 | Error Estimate | SSID | 216 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 217 | Receive Timestamp | 218 | | 219 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 220 | Session-Sender Sequence Number | 221 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 222 | Session-Sender Timestamp | 223 | | 224 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 225 | Session-Sender Error Estimate | MBZ | 226 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 227 |Ses-Sender TTL | MBZ | 228 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 229 | Type | Length | 230 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 231 ~ Value ~ 232 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 234 Figure 2: An example of an extended STAMP Session-Reflector test 235 packet format in unauthenticated mode 237 A STAMP Session-Reflector that does not support this specification, 238 will return the zeroed SSID field in the reflected STAMP test packet. 239 The Session-Sender MUST stop the session if it receives a zeroed SSID 240 field. 242 In the authenticated mode, location of SSID field is shown in 243 Figure 3 and Figure 4. 245 0 1 2 3 246 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 1 247 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 248 | Sequence Number | 249 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 250 | | 251 | MBZ (12 octets) | 252 | | 253 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 254 | Timestamp | 255 | | 256 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 257 | Error Estimate | SSID | 258 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 259 ~ ~ 260 | MBZ (68 octets) | 261 ~ ~ 262 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 263 | | 264 | HMAC (16 octets) | 265 | | 266 | | 267 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 269 Figure 3: Base STAMP Session-Sender test packet format in 270 authenticated mode 272 0 1 2 3 273 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 1 274 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 275 | Sequence Number | 276 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 277 | MBZ (12 octets) | 278 | | 279 | | 280 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 281 | Timestamp | 282 | | 283 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 284 | Error Estimate | SSID | 285 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 286 | MBZ (4 octets) | 287 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 288 | Receive Timestamp | 289 | | 290 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 291 | MBZ (8 octets) | 292 | | 293 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 294 | Session-Sender Sequence Number | 295 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 296 | MBZ (12 octets) | 297 | | 298 | | 299 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 300 | Session-Sender Timestamp | 301 | | 302 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 303 | Session-Sender Error Estimate | | 304 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + 305 | MBZ (6 octets) | 306 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 307 |Ses-Sender TTL | | 308 +-+-+-+-+-+-+-+-+ + 309 | | 310 | MBZ (15 octets) | 311 | | 312 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 313 | HMAC (16 octets) | 314 | | 315 | | 316 | | 317 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 319 Figure 4: Base STAMP Session-Reflector test packet format in 320 authenticated mode 322 4. TLV Extensions to STAMP 324 Type-Length-Value (TLV) encoding scheme provides a flexible extension 325 mechanism for optional informational elements. TLV is an optional 326 field in the STAMP test packet. Multiple TLVs MAY be placed in the 327 STAMP test packet. A TLV MAY be enclosed in a TLV. TLVs have the 328 two octets long Type field, two octets long Length field that is 329 equal to the length of the Value field in octets. Type values, see 330 Section 5.1, less than 32768 identify mandatory TLVs that MUST be 331 supported by an implementation. Type values greater than or equal to 332 32768 identify optional TLVs that SHOULD be ignored if the 333 implementation does not understand or support them. If a Type value 334 for TLV or sub-TLV is in the range for Vendor Private Use, the Length 335 MUST be at least 4, and the first four octets MUST be that vendor's 336 the Structure of Management Information (SMI) Private Enterprise 337 Number, in network octet order. The rest of the Value field is 338 private to the vendor. The following sections describe the use of 339 TLVs for STAMP that extend STAMP capability beyond its base 340 specification. 342 A STAMP node, whether Session-Sender or Session-Reflector, receiving 343 a test packet MUST determine whether the packet is a base STAMP 344 packet or includes one or more TLVs. The node MUST compare the value 345 in the Length field of the UDP header and the length of the base 346 STAMP test packet in the mode, unauthenticated or authenticated based 347 on the configuration of the particular STAMP test session. If the 348 difference between the two values is larger than the length of UDP 349 header, then the test packet includes one or more STAMP TLVs that 350 immediately follow the base STAMP test packet. 352 A system that has received a STAMP test packet with extension TLVs 353 MUST validate each TLV: 355 if the value of the Type field is one from the Mandatory TLV range 356 (Table 1) that the system does not support, the processing of the 357 TLV MUST be stopped. If the system is the Session-Reflector, it 358 MUST send the ICMP Parameter Problem message with Code set to 0 359 and the Pointer referring to the Type field of the TLV; 361 fixed-size TLVs are verified that the Length field value equals 362 the value defined for the particular type. If the values are not 363 equal, the processing of extension TLVs MUST be stopped. Also, if 364 the system is the Session-Reflector, it MUST send the ICMP 365 Parameter Problem message with Code set to 0 and the Pointer 366 referring to the Length field of the TLV. 368 Detected error events MUST be logged. Note that transmission of ICMP 369 Error messages and logging SHOULD be throttled. 371 4.1. Extra Padding TLV 373 0 1 2 3 374 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 1 375 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 376 | Extra Padding Type | Length | 377 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 378 | | 379 ~ Extra Padding ~ 380 | | 381 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 383 Figure 5: Extra Padding TLV 385 where fields are defined as the following: 387 o Extra Padding Type - TBA1 allocated by IANA Section 5.1 389 o Length - two octets long field equals length on the Extra Padding 390 field in octets. 392 o Extra Padding - a pseudo-random sequence of numbers. The field 393 MAY be filled with all zeros. 395 The Extra Padding TLV is similar to the Packet Padding field in 396 TWAMP-Test packet [RFC5357]. The Extra Padding TLV MUST be used to 397 create STAMP test packets of larger size that the base STAMP packet 398 [RFC8762]. The length of the base STAMP is 44 octets in the 399 unauthenticated mode or 112 octets in the authenticated mode. The 400 Extra Padding TLV MUST be the last TLV in a STAMP test packet. 402 4.2. Location TLV 404 STAMP Session-Sender MAY include the Location TLV to request 405 information from the Session-Reflector. The Session-Sender SHOULD 406 NOT fill any information fields except for Type and Length. The 407 Session-Reflector MUST validate the Length value against the address 408 family of the transport encapsulating the STAMP test packet. If the 409 Length field's value is invalid, the Session-Reflector MUST zero all 410 fields and MUST NOT return any information to the Session-Sender. 411 The Session-Reflector MUST ignore all other fields of the received 412 Location TLV. 414 0 1 2 3 415 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 1 416 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 417 | Location Type | Length | 418 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 419 | Source MAC | 420 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 421 | | Reserved | 422 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 423 ~ Destination IP Address ~ 424 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 425 ~ Source IP Address ~ 426 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 427 | Destination Port | Source Port | 428 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 430 Figure 6: Session-Reflector Location TLV 432 where fields are defined as the following: 434 o Location Type - TBA2 allocated by IANA Section 5.1 435 o Length - two octets long field equals the length of the Value 436 field in octets. The Length field value MUST equal 20 octets for 437 the IPv4 address family. For the IPv6 address family, the value 438 of the Length field MUST equal 44 octets. All other values are 439 invalid. 441 o Source MAC - 6 octets 48 bits long field. The Session-Reflector 442 MUST copy Source MAC of received STAMP packet into this field. 444 o Reserved - two octets long field. MUST be zeroed on transmission 445 and ignored on reception. 447 o Destination IP Address - IPv4 or IPv6 destination address of the 448 packet received by the STAMP Session-Reflector. 450 o Source IP Address - IPv4 or IPv6 source address of the packet 451 received by the STAMP Session-Reflector. 453 o Destination Port - two octets long UDP destination port number of 454 the received STAMP packet. 456 o Source Port - two octets long UDP source port number of the 457 received STAMP packet. 459 The Location TLV MAY be used to determine the last-hop addressing for 460 STAMP packets including source and destination IP addresses as well 461 as the MAC address of the last-hop router. Last-hop MAC address MAY 462 be monitored by the Session-Sender whether there has been a path 463 switch on the last hop, closest to the Session-Reflector. The IP 464 addresses and UDP port will indicate if there is a NAT router on the 465 path, and allows the Session-Sender to identify the IP address of the 466 Session-Reflector behind the NAT, detect changes in the NAT mapping 467 that could cause sending the STAMP packets to the wrong Session- 468 Reflector. 470 4.3. Timestamp Information TLV 472 STAMP Session-Sender MAY include the Timestamp Information TLV to 473 request information from the Session-Reflector. The Session-Sender 474 SHOULD NOT fill any information fields except for Type and Length. 475 The Session-Reflector MUST validate the Length value of the STAMP 476 test packet. If the value of the Length field is invalid, the 477 Session-Reflector MUST zero all fields and MUST NOT return any 478 information to the Session-Sender. 480 0 1 2 3 481 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 1 482 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 483 | Timestamp Information Type | Length | 484 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 485 | Sync. Src In | Timestamp In | Sync. Src Out | Timestamp Out | 486 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 488 Figure 7: Timestamp Information TLV 490 where fields are defined as the following: 492 o Timestamp Information Type - TBA3 allocated by IANA Section 5.1 494 o Length - two octets long field, set equal to the value 4. 496 o Sync Src In - one octet long field that characterizes the source 497 of clock synchronization at the ingress of Session-Reflector. 498 There are several methods to synchronize the clock, e.g., Network 499 Time Protocol (NTP) [RFC5905], Precision Time Protocol (PTP) 500 [IEEE.1588.2008], Synchronization Supply Unit (SSU) or Building 501 Integrated Timing Supply (BITS), or Global Positioning System 502 (GPS), Global Orbiting Navigation Satellite System (GLONASS) and 503 Long Range Navigation System Version C (LORAN-C). The value is 504 one of those listed in Table 4. 506 o Timestamp In - one octet long field that characterizes the method 507 by which the ingress of Session-Reflector obtained the timestamp 508 T2. A timestamp may be obtained with hardware assistance, via 509 software API from a local wall clock, or from a remote clock (the 510 latter is referred to as "control plane"). The value is one of 511 those listed in Table 6. 513 o Sync Src Out - one octet long field that characterizes the source 514 of clock synchronization at the egress of Session-Reflector. The 515 value is one of those listed in Table 4. 517 o Timestamp Out - one octet long field that characterizes the method 518 by which the egress of Session-Reflector obtained the timestamp 519 T3. The value is one of those listed in Table 6. 521 4.4. Class of Service TLV 523 The STAMP Session-Sender MAY include Class of Service (CoS) TLV in 524 the STAMP test packet. If the CoS TLV is present in the STAMP test 525 packet and the value of the DSCP1 field is zero, then the STAMP 526 Session-Reflector MUST copy the values of Differentiated Services 527 Code Point (DSCP) ECN fields from the received STAMP test packet into 528 DSCP2 and ECN fields respectively of the CoS TLV of the reflected 529 STAMP test packet. If the value of the DSCP1 field is non-zero, then 530 the STAMP Session-Reflector MUST use DSCP1 value from the CoS TLV in 531 the received STAMP test packet as DSCP value of STAMP reflected test 532 packet and MUST copy DSCP and ECN values of the received STAMP test 533 packet into DSCP2 and ECN fields of Class of Service TLV in the STAMP 534 reflected a packet. Upon receiving the reflected packet, the 535 Session-Sender,will save the DSCP and ECN values for analysis of the 536 CoS in the reverse direction. 538 0 1 2 3 539 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 1 540 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 541 | Class of Service Type | Length | 542 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 543 | DSCP1 | DSCP2 |ECN| Reserved | 544 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 546 Figure 8: Class of Service TLV 548 where fields are defined as the following: 550 o Class of Service Type - TBA4 allocated by IANA Section 5.1 552 o Length - two octets long field, set equal to the value 4. 554 o DSCP1 - The Differentiated Services Code Point (DSCP) intended by 555 the Session-Sender. To be used as the return DSCP from the 556 Session-Reflector. 558 o DSCP2 - The received value in the DSCP field at the Session- 559 Reflector in the forward direction. 561 o ECN - The received value in the ECN field at the Session-Reflector 562 in the forward direction. 564 o Reserved - 18 bits long field, must be zeroed in transmission and 565 ignored on receipt. 567 A STAMP Session-Sender that includes the CoS TLV sets the value of 568 the DSCP1 field and zeroes the value of the DSCP2 field. A STAMP 569 Session-Reflector that received the test packet with the CoS TLV MUST 570 include the CoS TLV in the reflected test packet. Also, the Session- 571 Reflector MUST copy the value of the DSCP field of the IP header of 572 the received STAMP test packet into the DSCP2 field in the reflected 573 test packet. At last, the Session-Reflector MUST set the value of 574 DSCP field's value in the IP header of the reflected test packet 575 equal to the value of the DSCP1 field of the received test packet. 577 Re-mapping of CoS in some use cases, for example, in mobile backhaul 578 networks is used to provide multiple services, i.e., 2G, 3G, LTE, 579 over the same network. But if it is misconfigured, then it is often 580 difficult to diagnose the root cause of the problem that is viewed as 581 an excessive packet drop of higher-level service while packet drop 582 for lower service packets is at a normal level. Using CoS TLV in 583 STAMP test helps to troubleshoot the existing problem and also verify 584 whether DiffServ policies are processing CoS as required by the 585 configuration. 587 4.5. Direct Measurement TLV 589 The Direct Measurement TLV enables collection of "in profile" IP 590 packets that had been transmitted and received by the Session-Sender 591 and Session-Reflector respectfully. The definition of "in-profile 592 packet" is outside the scope of this document and is left to the test 593 operators to determine. 595 0 1 2 3 596 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 1 597 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 598 | Direct Measurement Type | Length | 599 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 600 | Session-Sender Tx counter (S_TxC) | 601 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 602 | Session-Reflector Rx counter (R_RxC) | 603 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 604 | Session-Reflector Tx counter (R_TxC) | 605 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 607 Figure 9: Direct Measurement TLV 609 where fields are defined as the following: 611 o Direct Measurement Type - TBA5 allocated by IANA Section 5.1 613 o Length - two octets long field equals length on the Value field in 614 octets. Length field value MUST equal 12 octets. 616 o Session-Sender Tx counter (S_TxC) is four octets long field. 618 o Session-Reflector Rx counter (R_RxC) is four octets long field. 619 MUST be zeroed by the Session-Sender and filled by the Session- 620 Reflector. 622 o Session-Reflector Tx counter (R_TxC) is four octets long field. 623 MUST be zeroed by the Session-Sender and filled by the Session- 624 Reflector. 626 4.6. Access Report TLV 628 A STAMP Session-Sender MAY include Access Report TLV (Figure 10) to 629 indicate changes to the access network status to the Session- 630 Reflector. The definition of an access network is outside the scope 631 of this document. 633 0 1 2 3 634 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 1 635 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 636 | Access Report Type | Length | 637 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 638 | ID | Resv | Return Code | Reserved | 639 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 641 Figure 10: Access Report TLV 643 where fields are defined as follows: 645 o Access Report Type - TBA6 allocated by IANA Section 5.1. 647 o Length - two octets long field, set equal to the value 4. 649 o ID (Access ID) - four bits long field that identifies the access 650 network, e.g., 3GPP (Radio Access Technologies specified by 3GPP) 651 or Non-3GPP (accesses that are not specified by 3GPP) [TS23501]. 652 The value is one of those listed below: 654 * 1 - 3GPP Network 656 * 2 - Non-3GPP Network 658 All other values are invalid and the TLV that contains it MUST be 659 discarded. 661 o Resv - four bits long field, must be zeroed on transmission and 662 ignored on receipt. 664 o Return Code - one octet long field that identifies the report 665 signal, e.g., available, unavailable. The value is passed, 666 supplied to the STAMP end-point through some mechanism that is 667 outside the scope of this document. The value is one of those 668 listed in Section 5.4. 670 o Reserved - two octets long field, must be zeroed on transmission 671 and ignored on receipt. 673 The STAMP Session-Sender that includes the Access Report TLV sets the 674 value of the Access ID field according to the type of access network 675 it reports on. Also, the Session-Sender sets the value of the Return 676 Code field to reflect the operational state of the access network. 677 The mechanism to determine the state of the access network is outside 678 the scope of this specification. A STAMP Session-Reflector that 679 received the test packet with the Access Report TLV MUST include the 680 Access Report TLV in the reflected test packet. The Session- 681 Reflector MUST set the value of the Access ID and Return Code fields 682 equal to the values of the corresponding fields from the test packet 683 it has received. 685 The Session-Sender MUST also arm a retransmission timer after sending 686 a test packet that includes the Access Report TLV. This timer MUST 687 be disarmed upon the reception of the reflected STAMP test packet 688 that includes Access Report TLV. In the event the timer expires 689 before such a packet is received, the Session-Sender MUST retransmit 690 the STAMP test packet that contains the Access Report TLV. This 691 retransmission SHOULD be repeated up to four times before the 692 procedure is aborted. Setting the value for the retransmission timer 693 is based on local policies, network environment. The default value 694 of the retransmission timer for Access Report TLV SHOULD be three 695 seconds. An implementation MUST provide control of the 696 retransmission timer value and the number of retransmissions. 698 The Access Report TLV is used by the Performance Measurement Function 699 (PMF) components of the Access Steering, Switching and Splitting 700 feature for 5G networks [TS23501]. The PMF component in the User 701 Equipment acts as the STAMP Session-Sender, and the PMF component in 702 the User Plane Function acts as the STAMP Session-Reflector. 704 4.7. Follow-up Telemetry TLV 706 A Session-Reflector might be able to put in the Timestamp field only 707 an "SW Local" (see Table 6) timestamp. But the hosting system might 708 provide the timestamp closer to the start of the actual packet 709 transmission even though when it is not possible to deliver the 710 information to the Session-Sender in the packet itself. This 711 timestamp might nevertheless be important for the Session-Sender, as 712 it improves the accuracy of measuring network delay by minimizing the 713 impact of egress queuing delays on the measurement. 715 A STAMP Session-Sender MAY include the Follow-up Telemetry TLV to 716 request information from the Session-Reflector. The Session-Sender 717 MUST set the Follow-up Telemetry Type and Length fields to their 718 appropriate values. Sequence Number and Timestamp fields MUST be 719 zeroed on transmission by the Session-Sender and ignored by the 720 Session-Reflector upon receipt of the STAMP test packet that includes 721 the Follow-up Telemetry TLV. The Session-Reflector MUST validate the 722 Length value of the STAMP test packet. If the value of the Length 723 field is invalid, the Session-Reflector MUST zero Sequence Number and 724 Timestamp fields. If the Session-Reflector is in stateless mode 725 (defined in Section 4.2 [RFC8762]), it MUST zero Sequence Number and 726 Timestamp fields. 728 0 1 2 3 729 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 1 730 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 731 | Follow-up Telemetry Type | Length | 732 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 733 | Sequence Number | 734 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 735 | Follow-up Timestamp | 736 | | 737 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 738 | Timestamp M | Reserved | 739 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 741 Figure 11: Follow-up Telemetry TLV 743 where fields are defined as follows: 745 o Follow-up Telemetry Type - TBA7 allocated by IANA Section 5.1. 747 o Length - two octets long field, set equal to the value 16 octets. 749 o Sequence Number - four octets long field indicating the sequence 750 number of the last packet reflected in the same STAMP-test 751 session. Since the Session-Reflector runs in the stateful mode 752 (defined in Section 4.2 [RFC8762]), it is the Session-Reflector's 753 Sequence Number of the previous reflected packet. 755 o Follow-up Timestamp - eight octets long field, with the format 756 indicated by the Z flag of the Error Estimate field of the packet 757 transmitted by a Session-Reflector, as described in Section 4.1 758 [RFC8762]. It carries the timestamp when the reflected packet 759 with the specified sequence number was sent. 761 o Timestamp M(ode) - one octet long field that characterizes the 762 method by which the entity that transmits a reflected STAMP packet 763 obtained the Follow-up Timestamp. The value is one of those 764 listed in Table 6. 766 o Reserved - the three octets-long field. Its value MUST be zeroed 767 on transmission and ignored on receipt. 769 4.8. HMAC TLV 771 The STAMP authenticated mode protects the integrity of data collected 772 in the STAMP base packet. STAMP extensions are designed to provide 773 valuable information about the condition of a network, and protecting 774 the integrity of that data is also essential. The keyed Hashed 775 Message Authentication Code (HMAC) TLV MUST be included in a STAMP 776 test packet in the authenticated mode, excluding when the only TLV 777 present is Extra Padding TLV. The HMAC TLV MUST follow all TLVs 778 included in a STAMP test packet, except for the Extra Padding TLV. 779 The HMAC TLV MAY be used to protect the integrity of STAMP extensions 780 in STAMP unauthenticated mode. 782 0 1 2 3 783 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 1 784 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 785 | HMAC Type | Length | 786 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 787 | | 788 | HMAC | 789 | | 790 | | 791 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 793 Figure 12: HMAC TLV 795 where fields are defined as follows: 797 o HMAC Type - is two octets long field, value TBA8 allocated by IANA 798 Section 5.1. 800 o Length - two octets long field, set equal to the value 16 octets. 802 o HMAC - is 16 octets long field that carries HMAC digest of the 803 text of all preceding TLVs. 805 As defined in [RFC8762], STAMP uses HMAC-SHA-256 truncated to 128 806 bits ([RFC4868]). All considerations regarding using the key and key 807 distribution and management listed in Section 4.4 of [RFC8762] are 808 fully applicable to the use of the HMAC TLV. HMAC is calculated as 809 defined in [RFC2104] over text as the concatenation of all preceding 810 TLVs. The digest then MUST be truncated to 128 bits and written into 811 the HMAC field. In the authenticated mode, HMAC MUST be verified 812 before using any data in the included STAMP TLVs. If HMAC 813 verification by the Session-Reflector fails, then an ICMP Parameter 814 Problem message MUST be generated (with consideration of limiting the 815 rate of error messages). The Code value MUST be set to 0 and the 816 Pointer identifying HMAC Type. Also, both Session-Sender and 817 Session-Reflector SHOULD log the notification that HMAC verification 818 of STAMP TLVs failed. The packet that failed HMAC verification MUST 819 be dropped. 821 5. IANA Considerations 823 5.1. STAMP TLV Registry 825 IANA is requested to create the STAMP TLV Type registry. All code 826 points in the range 1 through 32759 in this registry shall be 827 allocated according to the "IETF Review" procedure as specified in 828 [RFC8126]. Code points in the range 32760 through 65279 in this 829 registry shall be allocated according to the "First Come First 830 Served" procedure as specified in [RFC8126]. Remaining code points 831 are allocated according to Table 1: 833 +---------------+-------------------------+-------------------------+ 834 | Value | Description | Reference | 835 +---------------+-------------------------+-------------------------+ 836 | 0 | Reserved | This document | 837 | 1- 32767 | Mandatory TLV, | IETF Review | 838 | | unassigned | | 839 | 32768 - 65279 | Optional TLV, | First Come First Served | 840 | | unassigned | | 841 | 65280 - 65519 | Experimental | This document | 842 | 65520 - 65534 | Private Use | This document | 843 | 65535 | Reserved | This document | 844 +---------------+-------------------------+-------------------------+ 846 Table 1: STAMP TLV Type Registry 848 This document defines the following new values in the Mandatory TLV 849 range of the STAMP TLV Type registry: 851 +-------+-----------------------+---------------+ 852 | Value | Description | Reference | 853 +-------+-----------------------+---------------+ 854 | TBA1 | Extra Padding | This document | 855 | TBA2 | Location | This document | 856 | TBA3 | Timestamp Information | This document | 857 | TBA4 | Class of Service | This document | 858 | TBA5 | Direct Measurement | This document | 859 | TBA6 | Access Report | This document | 860 | TBA7 | Follow-up Telemetry | This document | 861 | TBA8 | HMAC | This document | 862 +-------+-----------------------+---------------+ 864 Table 2: STAMP Types 866 5.2. Synchronization Source Sub-registry 868 IANA is requested to create Synchronization Source sub-registry as 869 part of the STAMP TLV Type registry. All code points in the range 1 870 through 127 in this registry shall be allocated according to the 871 "IETF Review" procedure as specified in [RFC8126]. Code points in 872 the range 128 through 239 in this registry shall be allocated 873 according to the "First Come First Served" procedure as specified in 874 [RFC8126]. Remaining code points are allocated according to Table 1: 876 +-----------+--------------+-------------------------+ 877 | Value | Description | Reference | 878 +-----------+--------------+-------------------------+ 879 | 0 | Reserved | This document | 880 | 1- 127 | Unassigned | IETF Review | 881 | 128 - 239 | Unassigned | First Come First Served | 882 | 240 - 249 | Experimental | This document | 883 | 250 - 254 | Private Use | This document | 884 | 255 | Reserved | This document | 885 +-----------+--------------+-------------------------+ 887 Table 3: Synchronization Source Sub-registry 889 This document defines the following new values in the Synchronization 890 Source sub-registry: 892 +-------+---------------------+---------------+ 893 | Value | Description | Reference | 894 +-------+---------------------+---------------+ 895 | 1 | NTP | This document | 896 | 2 | PTP | This document | 897 | 3 | SSU/BITS | This document | 898 | 4 | GPS/GLONASS/LORAN-C | This document | 899 | 5 | Local free-running | This document | 900 +-------+---------------------+---------------+ 902 Table 4: Synchronization Sources 904 5.3. Timestamping Method Sub-registry 906 IANA is requested to create Timestamping Method sub-registry as part 907 of the STAMP TLV Type registry. All code points in the range 1 908 through 127 in this registry shall be allocated according to the 909 "IETF Review" procedure as specified in [RFC8126]. Code points in 910 the range 128 through 239 in this registry shall be allocated 911 according to the "First Come First Served" procedure as specified in 912 [RFC8126]. Remaining code points are allocated according to Table 1: 914 +-----------+--------------+-------------------------+ 915 | Value | Description | Reference | 916 +-----------+--------------+-------------------------+ 917 | 0 | Reserved | This document | 918 | 1- 127 | Unassigned | IETF Review | 919 | 128 - 239 | Unassigned | First Come First Served | 920 | 240 - 249 | Experimental | This document | 921 | 250 - 254 | Private Use | This document | 922 | 255 | Reserved | This document | 923 +-----------+--------------+-------------------------+ 925 Table 5: Timestamping Method Sub-registry 927 This document defines the following new values in the Timestamping 928 Methods sub-registry: 930 +-------+---------------+---------------+ 931 | Value | Description | Reference | 932 +-------+---------------+---------------+ 933 | 1 | HW Assist | This document | 934 | 2 | SW local | This document | 935 | 3 | Control plane | This document | 936 +-------+---------------+---------------+ 938 Table 6: Timestamping Methods 940 5.4. Return Code Sub-registry 942 IANA is requested to create Return Code sub-registry as part of STAMP 943 TLV Type registry. All code points in the range 1 through 127 in 944 this registry shall be allocated according to the "IETF Review" 945 procedure as specified in [RFC8126]. Code points in the range 128 946 through 239 in this registry shall be allocated according to the 947 "First Come First Served" procedure as specified in [RFC8126]. 948 Remaining code points are allocated according to Table 7: 950 +-----------+--------------+-------------------------+ 951 | Value | Description | Reference | 952 +-----------+--------------+-------------------------+ 953 | 0 | Reserved | This document | 954 | 1- 127 | Unassigned | IETF Review | 955 | 128 - 239 | Unassigned | First Come First Served | 956 | 240 - 249 | Experimental | This document | 957 | 250 - 254 | Private Use | This document | 958 | 255 | Reserved | This document | 959 +-----------+--------------+-------------------------+ 961 Table 7: Return Code Sub-registry 963 This document defines the following new values in the Return Code 964 sub-registry: 966 +-------+---------------------+---------------+ 967 | Value | Description | Reference | 968 +-------+---------------------+---------------+ 969 | 1 | Network available | This document | 970 | 2 | Network unavailable | This document | 971 +-------+---------------------+---------------+ 973 Table 8: Return Codes 975 6. Security Considerations 977 This document defines extensions to STAMP [RFC8762] and inherits all 978 the security considerations applicable to the base protocol. 979 Additionally, the HMAC TLV is defined in this document to protect the 980 integrity of optional STAMP extensions. The use of HMAC TLV is 981 discussed in detail in Section 4.8. 983 7. Acknowledgments 985 Authors much appreciate the thorough review and thoughtful comments 986 received from Tianran Zhou, Rakesh Gandhi, Yuezhong Song and Yali 987 Wang. Authors express their gratitude to Al Morton for his comments 988 and the most valuable suggestions. 990 8. Contributors 992 The following people contributed text to this document: 994 Guo Jun 995 ZTE Corporation 996 68# Zijinghua Road 997 Nanjing, Jiangsu 210012 998 P.R.China 1000 Phone: +86 18105183663 1001 Email: guo.jun2@zte.com.cn 1003 9. References 1005 9.1. Normative References 1007 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1008 Requirement Levels", BCP 14, RFC 2119, 1009 DOI 10.17487/RFC2119, March 1997, 1010 . 1012 [RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J. 1013 Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)", 1014 RFC 5357, DOI 10.17487/RFC5357, October 2008, 1015 . 1017 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 1018 Writing an IANA Considerations Section in RFCs", BCP 26, 1019 RFC 8126, DOI 10.17487/RFC8126, June 2017, 1020 . 1022 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1023 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1024 May 2017, . 1026 [RFC8762] Mirsky, G., Jun, G., Nydell, H., and R. Foote, "Simple 1027 Two-Way Active Measurement Protocol", RFC 8762, 1028 DOI 10.17487/RFC8762, March 2020, 1029 . 1031 9.2. Informative References 1033 [IEEE.1588.2008] 1034 "Standard for a Precision Clock Synchronization Protocol 1035 for Networked Measurement and Control Systems", 1036 IEEE Standard 1588, March 2008. 1038 [RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed- 1039 Hashing for Message Authentication", RFC 2104, 1040 DOI 10.17487/RFC2104, February 1997, 1041 . 1043 [RFC4868] Kelly, S. and S. Frankel, "Using HMAC-SHA-256, HMAC-SHA- 1044 384, and HMAC-SHA-512 with IPsec", RFC 4868, 1045 DOI 10.17487/RFC4868, May 2007, 1046 . 1048 [RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch, 1049 "Network Time Protocol Version 4: Protocol and Algorithms 1050 Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010, 1051 . 1053 [TS23501] 3GPP (3rd Generation Partnership Project), "Technical 1054 Specification Group Services and System Aspects; System 1055 Architecture for the 5G System; Stage 2 (Release 16)", 1056 3GPP TS23501, 2019. 1058 Authors' Addresses 1060 Greg Mirsky 1061 ZTE Corp. 1063 Email: gregimirsky@gmail.com 1065 Xiao Min 1066 ZTE Corp. 1068 Email: xiao.min2@zte.com.cn 1070 Henrik Nydell 1071 Accedian Networks 1073 Email: hnydell@accedian.com 1075 Richard Foote 1076 Nokia 1078 Email: footer.foote@nokia.com 1080 Adi Masputra 1081 Apple Inc. 1082 One Apple Park Way 1083 Cupertino, CA 95014 1084 USA 1086 Email: adi@apple.com 1088 Ernesto Ruffini 1089 OutSys 1090 via Caracciolo, 65 1091 Milano 20155 1092 Italy 1094 Email: eruffini@outsys.org