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Wang 5 Expires: January 13, 2022 Huawei Technologies 6 July 12, 2021 8 ACH6 for OAM in Segment Routing 9 draft-yang-spring-ach6-oam-sr-00 11 Abstract 13 This document defines an OAM toolset encapsulated in ACH6 to provide 14 the functions of performance measurement, continuity check and 15 verification to an SRv6 path. 17 Requirements Language 19 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 20 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 21 "OPTIONAL" in this document are to be interpreted as described in BCP 22 14 [RFC2119] [RFC8174] when, and only when, they appear in all 23 capitals, as shown here. 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 January 13, 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 49 (https://trustee.ietf.org/license-info) in effect on the date of 50 publication of this document. Please review these documents 51 carefully, as they describe your rights and restrictions with respect 52 to this document. Code Components extracted from this document must 53 include Simplified BSD License text as described in Section 4.e of 54 the Trust Legal Provisions and are provided without warranty as 55 described in the Simplified BSD License. 57 Table of Contents 59 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 60 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 61 3. ACH6 OAM for SRv6 . . . . . . . . . . . . . . . . . . . . . . 3 62 3.1. ACH6 OAM Message . . . . . . . . . . . . . . . . . . . . 3 63 3.2. ACH6 On-Demand Echo Request/Reply . . . . . . . . . . . . 3 64 3.3. ACH6 Proactive Continuity Check . . . . . . . . . . . . . 5 65 3.4. ACH6 Performance Measurement . . . . . . . . . . . . . . 7 66 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 67 5. Security Considerations . . . . . . . . . . . . . . . . . . . 9 68 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9 69 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 70 7.1. Normative References . . . . . . . . . . . . . . . . . . 9 71 7.2. Informative References . . . . . . . . . . . . . . . . . 9 72 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 74 1. Introduction 76 ACH6 [I-D.yang-spring-ach6-sr] provides a method of supporting an OAM 77 toolset with a unified TLV format in Segment Routing over IPv6 78 network. There are several advantages: 80 o An Associated Channel ID in ACH6 provides a unified identifier to 81 OAM sessions for a specific SRv6 path. 83 o In Segment Routing networks, ACH6 TLV is proposed to be 84 encapsulated in IPv6 Destination Options Header. Together with 85 IPv6 Segment Routing Header, OAM functions like continuity check 86 and performance management can be monitored either hop-by-hop on 87 every SR endpoint or end-to-end from the first endpoint to the 88 last. 90 o By leveraging native semantics of IPv6 extension headers, ACH6 OAM 91 messages target to be processed in fast path to improve OAM 92 accuracy and efficiency. 94 o By leveraging native semantics of IPv6 extension headers, ACH6 OAM 95 can help network nodes reduce OAM configurations and session 96 management. 98 In this method, ACH6 OAM categorizes OAM functionalities into three 99 types of messages, including On-demand Echo Request/Reply, Proactive 100 Continuity Check and Performance Measurement. 102 2. Terminology 104 This document uses the following terms: 106 OAM: Operations, Administration, and Maintenance 108 ACH6: Associated CHannel over IPv6 110 3. ACH6 OAM for SRv6 112 3.1. ACH6 OAM Message 114 Figure 1 defines the format of ACH6 OAM message. 116 0 1 2 3 117 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 1 118 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 119 | Channel Type = TBA | 120 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 121 ~ Associated Channel ID ~ 122 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 123 | ~ 124 ~ OAM Message Body (Variable) ~ 125 ~ | 126 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 128 Figure 1 ACH6 OAM Message Format 130 ACH6 Channel Type indicates which type of OAM message is encapsulated 131 in the following OAM message body, and OAM message body contains the 132 OAM messages. Three types of OAM messages are defined: 134 o TBA 1 = On-demand Echo Request/Reply 136 o TBA 2 = Proactive Continuity Check 138 o TBA 3 = Performance Measurement 140 3.2. ACH6 On-Demand Echo Request/Reply 142 On-demand Echo Request/Reply provides a method of on-demand 143 continuity check and connectivity verification. Figure 2 defines 144 ACH6 OAM format of On-demand Echo Request/Reply message. 146 0 1 2 3 147 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 1 148 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 149 | Channel Type = TBA1 | 150 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 151 ~ Associated Channel ID ~ 152 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 153 | Echo Req/Rep | Reply Mode | Return Code | Reserved | 154 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 155 | Sequence Number | 156 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 157 ~ sub-TLVs (optional) ~ 158 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 160 Figure 2 ACH6 OAM On Demand Echo Request/Reply Message 162 Associated Channel ID: indicates the identifier of OAM session. 164 Message Type: 166 o 1 = Echo Request 168 o 2 = Echo Reply 170 Reply Mode: 172 o 1 = Do not reply 174 o 2 = Reply via an IPv6 UDP packet 176 o 3 = Reply via an IPv6 packet without payload 178 o 4 = Reply via application-level control channel 180 Return code: 182 o 0 = No return code 184 o 1 = Malformed echo request received 186 o 2 = One or more of the TLVs was not understood 188 o 3 = Packet-rorward-success 190 o 4 = No route to destination 192 o 5 = Communication with destination administratively prohibited 193 o 6 = Beyond scope of source address 195 o 7 = Address unreachable 197 o 8 = Port unreachable 199 o 9 = Source address failed ingress/egress policy 201 o 10 = Reject route to destination 203 o 11 = Exceeding the minimum IPv6 MTU 205 o 12 = Hop limit exceeded in transit 207 o 13 = Fragment reassembly time exceeded 209 o 14 = Erroneous header field encountered 211 o 15 = Unrecognized Next Header type encountered 213 o 16 = Unrecognized IPv6 option encountered 215 Sequence number: is allocated by the sender of echo request to detect 216 whether the reply packet is lost. 218 3.3. ACH6 Proactive Continuity Check 220 Proactive Continuity Check provides a method of proactive continuity 221 check to continuously detect the path status and fault. Figure 3 222 defines ACH6 OAM format of Proactive Continuity Check message. 224 0 1 2 3 225 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 1 226 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 227 | Channel Type = TBA2 | 228 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 229 ~ Associated Channel ID ~ 230 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 231 | Diag |Sta| Flag | Reserved | Detect Multi | 232 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 233 | Desired Min TX Interval | 234 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 235 | Required Min TX Interval | 236 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 237 | Required Min Echo RX Interval | 238 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 240 Figure 3 ACH6 OAM ProCC Message 242 Associated Channel ID: indicates the identifier of OAM session. 244 Diag: 246 o 0 = no diagnostic 248 o 1 = control detection time expired 250 o 2 = echo function failed 252 o 3 = neighbor signaled session down 254 o 4 = forwarding plane reset 256 o 5 = path down 258 o 6 = concatenated path down 260 o 7 = administratively down 262 o 8 = reverse concatenated path down 264 o 9-31 = reserved for future use 266 State: 268 o 0 = adminDown 270 o 1 = down 272 o 2 = Init 274 o 3 = up 276 Flag: 278 o P flag: if set, the transmitting node is requesting verification 279 of connectivity, or of a parameter change, and is expecting a 280 packet with the F bit in reply. If clear, the transmitting node 281 is not requesting verification. 283 o F flag: if set, the transmitting node is responding to a received 284 Proactive Continuity Check packet that had the P bit set. If 285 clear, the transmitting node is not responding to a requesting 286 packet that had the P bit set. 288 o D flag: if set, Demand mode is active in the transmitting node. 289 The node wishes to operate in Demand mode and direct the remote 290 node to cease the periodic transmission of Proactive Continuity 291 Check packets. If clear, Demand mode is not active in the 292 transmitting node. 294 o M flag: this bit is reserved for future point-to-multipoint 295 extensions to ACH6 Proactive Continuity Check. It MUST be zero on 296 both transmit and receipt. 298 Detect Mult: detection time multiplier. 300 Desired Min TX Interval: this is the minimum interval, in 301 microseconds, that the local system would like to use when 302 transmitting ACH6 Proactive Continuity Check packets. 304 Required Min RX Interval: this is the minimum interval, in 305 microseconds, between received ACH6 Proactive Continuity Check 306 packets that this system is capable of supporting, less any jitter 307 applied by the sender. 309 Required Min Echo RX Interval: this is the minimum interval, in 310 microseconds, between received Echo packets that this system is 311 capable of supporting, less any jitter applied by the sender. 313 3.4. ACH6 Performance Measurement 315 Performance Measurement provides a method of measuring packet loss 316 and delay. Figure 4 defines ACH6 OAM format of Performance 317 Measurement message. 319 0 1 2 3 320 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 1 321 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 322 | Channel Type = TBA3 | 323 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 324 ~ Associated Channel ID ~ 325 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 326 | Sender Sequence Number | 327 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 328 | Reflector Sequence Number | 329 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 330 ~ TimeStamp1 ~ 331 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 332 ~ TimeStamp2 ~ 333 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 334 ~ TimeStamp3 ~ 335 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 336 ~ TimeStamp4 ~ 337 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 338 | Padding (MBZ, variable) | 339 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 341 Figure 4 ACH6 OAM Performance Measurement Message 343 Associated Channel ID: indicates the identifier of OAM session. 345 Sender Sequence Number: the counter of performance measurement test 346 packets sent from sender 348 Reflector Sequence Number: the counter of performace measurement test 349 packets set by reflector 351 Timestamp 1-4: When a query is sent from A, timestamp 1 is set to T1, 352 timestamp 2-4 fields are set to 0. When the query is received at B, 353 timestamp 2 is set to T2. In this case, B copies timestamp 1 to 354 timestamp 3, copies timestamp 2 to timestamp 4, and initializes 355 timestamp 1 and timestamp 2 to 0. When B sends a response, timestamp 356 1 is set to T3. When a response is received at A, timestamp 2 is set 357 to T4. 359 4. IANA Considerations 361 o This document requests IANA to assign a codepoint of On-demand 362 Echo Request/Reply of ACH6 Channel Types. 364 o This document requests IANA to assign a codepoint of Proactive 365 Continuity Check of ACH6 Channel Types. 367 o This document requests IANA to assign a codepoint of Performance 368 Measurement of ACH6 Channel Types. 370 5. Security Considerations 372 TBD 374 6. Acknowledgements 376 TBD 378 7. References 380 7.1. Normative References 382 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 383 Requirement Levels", BCP 14, RFC 2119, 384 DOI 10.17487/RFC2119, March 1997, 385 . 387 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 388 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 389 May 2017, . 391 7.2. Informative References 393 [I-D.yang-spring-ach6-sr] 394 Yang, F. and T. Zhou, "ACH6 in Segment Routing", draft- 395 yang-spring-ach6-sr-00 (work in progress), July 2021. 397 Authors' Addresses 399 Fan Yang 400 Huawei Technologies 401 Beijing 402 China 404 Email: shirley.yangfan@huawei.com 406 Tianran Zhou 407 Huawei Technologies 408 Beijing 409 China 411 Email: zhoutianran@huawei.com 412 Yali Wang 413 Huawei Technologies 414 Beijing 415 China 417 Email: wangyali11@huawei.com