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Checking references for intended status: Experimental ---------------------------------------------------------------------------- == Outdated reference: A later version (-13) exists of draft-ietf-sfc-ioam-nsh-04 -- Obsolete informational reference (is this intentional?): RFC 8321 (Obsoleted by RFC 9341) Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 SFC Working Group G. Mirsky 3 Internet-Draft ZTE Corp. 4 Intended status: Experimental G. Fioccola 5 Expires: December 31, 2020 Huawei Technologies 6 T. Mizrahi 7 Huawei Network.IO Innovation Lab 8 June 29, 2020 10 Performance Measurement (PM) with Alternate Marking Method in Service 11 Function Chaining (SFC) Domain 12 draft-mirsky-sfc-pmamm-10 14 Abstract 16 This document describes how the alternate marking method can be used 17 as the efficient performance measurement method taking advantage of 18 the actual data flows in a Service Function Chaining (SFC) domain. 20 Status of This Memo 22 This Internet-Draft is submitted in full conformance with the 23 provisions of BCP 78 and BCP 79. 25 Internet-Drafts are working documents of the Internet Engineering 26 Task Force (IETF). Note that other groups may also distribute 27 working documents as Internet-Drafts. The list of current Internet- 28 Drafts is at https://datatracker.ietf.org/drafts/current/. 30 Internet-Drafts are draft documents valid for a maximum of six months 31 and may be updated, replaced, or obsoleted by other documents at any 32 time. It is inappropriate to use Internet-Drafts as reference 33 material or to cite them other than as "work in progress." 35 This Internet-Draft will expire on December 31, 2020. 37 Copyright Notice 39 Copyright (c) 2020 IETF Trust and the persons identified as the 40 document authors. All rights reserved. 42 This document is subject to BCP 78 and the IETF Trust's Legal 43 Provisions Relating to IETF Documents 44 (https://trustee.ietf.org/license-info) in effect on the date of 45 publication of this document. Please review these documents 46 carefully, as they describe your rights and restrictions with respect 47 to this document. Code Components extracted from this document must 48 include Simplified BSD License text as described in Section 4.e of 49 the Trust Legal Provisions and are provided without warranty as 50 described in the Simplified BSD License. 52 Table of Contents 54 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 55 2. Conventions used in this document . . . . . . . . . . . . . . 3 56 2.1. Acronyms . . . . . . . . . . . . . . . . . . . . . . . . 3 57 2.2. Requirements Language . . . . . . . . . . . . . . . . . . 3 58 3. Mark Field in NSH Base Header . . . . . . . . . . . . . . . . 3 59 4. Theory of Operation . . . . . . . . . . . . . . . . . . . . . 4 60 4.1. Single Mark Enabled Measurement . . . . . . . . . . . . . 4 61 4.2. Multiplexed Mark Enabled Measurement . . . . . . . . . . 5 62 4.3. Residence Time Measurement with the Alternate Marking 63 Method . . . . . . . . . . . . . . . . . . . . . . . . . 5 64 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 65 5.1. Mark Field in NSH Base Header . . . . . . . . . . . . . . 6 66 6. Security Considerations . . . . . . . . . . . . . . . . . . . 6 67 7. Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . 6 68 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 69 8.1. Normative References . . . . . . . . . . . . . . . . . . 7 70 8.2. Informative References . . . . . . . . . . . . . . . . . 7 71 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 73 1. Introduction 75 [RFC7665] introduced the architecture of a Service Function Chain 76 (SFC) in the network and defined its components. These include 77 Classifier, Service Function Forwarder (SFF), Service Function (SF), 78 and Service Function proxy. [I-D.ietf-sfc-oam-framework] provides a 79 reference framework for Operations, Administration and Maintenance 80 (OAM) for SFC. [RFC8321] describes the hybrid performance 81 measurement method, which can be used to measure packet loss, 82 latency, and jitter on live traffic. Because this method is based on 83 marking consecutive batches of packets the method often referred to 84 as Alternate Marking Method (AMM). 86 This document defines how packet loss and delay metrics of a service 87 flow over end-to-end (Session-Reflector) or any segment of the SFC 88 can be measured using AMM. This document is aligned with the SFC OAM 89 Performance Measurement requirements defined in 90 [I-D.ietf-sfc-oam-framework]. It states that any SFC-aware network 91 device must have the ability to perform loss and delay measurements 92 over the service function chain as a unit, i.e., E2E, or to a 93 specific segment of service function through the SFC. Besides,, AMM 94 can be used in combination with [I-D.ietf-sfc-ioam-nsh] and 95 complement it to achieve the SFC performance measurement objective. 97 2. Conventions used in this document 99 2.1. Acronyms 101 AMM: Alternate Marking Method 103 OAM: Operations, Administration and Maintenance 105 SFC: Service Function Chain 107 SF: Service Function 109 SFF: Service Function Forwarder 111 SFP: Service Function Path 113 NSH: Network Service Header 115 E2E end-to-end 117 2.2. Requirements Language 119 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 120 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 121 "OPTIONAL" in this document are to be interpreted as described in BCP 122 14 [RFC2119] [RFC8174] when, and only when, they appear in all 123 capitals, as shown here. 125 3. Mark Field in NSH Base Header 127 [RFC8300] defines the format of the Network Service Header (NSH). 129 0 1 2 3 130 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 1 131 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 132 |Ver|O|M| TTL | Length |U|U|U|U|MD Type| Proto | 133 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 135 Figure 1: NSH Base format 137 This document defines the one-bit long field, referred to as Mark 138 field (M in Figure 1, as part of NSH Base and designated for the 139 alternate marking performance measurement method [RFC8321]. The Mark 140 field MUST be set to 0 at initialization of NSH and ignored on the 141 receipt when the method is not in use. The Mark field MUST NOT be 142 used in defining forwarding and/or quality of service treatment of an 143 SFC packet. The Mark field MUST be used only for the performance 144 measurement of data traffic in the SFC layer. Though the setting of 145 the field to any value likely not affect forwarding and/or quality of 146 service treatment of a packet, the alternate marking method in SFC 147 layer is characterized as an example of a hybrid performance 148 measurement method according to [RFC7799]. 150 4. Theory of Operation 152 The marking method can be successfully used in the SFC. Without 153 limiting any generality consider SFC presented in Figure 2. Any 154 combination of markings, Loss and/or Delay, can be applied to a 155 service flow by any component of the SFC at either ingress or egress 156 point to perform node, link, segment or E2E measurement to detect 157 performance degradation defect and localize it efficiently. 159 +---+ +---+ +---+ +---+ +---+ +---+ 160 |SF1| |SF2| |SF3| |SF4| |SF5| |SF6| 161 +---+ +---+ +---+ +---+ +---+ +---+ 162 \ / \ / \ / 163 +----------+ +----+ +----+ +----+ 164 |Classifier|---|SFF1|---------|SFF2|---------|SFF3| 165 +----------+ +----+ +----+ +----+ 167 Figure 2: SFC network 169 Using the marking method, a component of the SFC creates distinct 170 sub-flows in the particular service traffic over SFC. Each sub-flow 171 consists of consecutive blocks that are unambiguously recognizable by 172 a monitoring point at any component of the SFC and can be measured to 173 calculate packet loss and/or packet delay metrics. 175 4.1. Single Mark Enabled Measurement 177 As explained in the [RFC8321], marking can be applied to delineate 178 blocks of packets based either on the equal number of packets in a 179 block or based on the same time interval. The latter method offers 180 better control as it allows a better account for capabilities of 181 downstream nodes to report statistics related to batches of packets 182 and, at the same time, time resolution that affects defect detection 183 interval. 185 The Mark flag is used to create distinctive flows to measure the 186 packet loss by switching the value of the Mark flag every N-th packet 187 or at specified time intervals. Delay metrics MAY be calculated with 188 the alternate flow using any of the following methods: 190 o First/Last Packet Delay calculation: whenever the marking, i.e., 191 the value of Mark flag changes a component of the SFC can store 192 the timestamp of the first/last packet of the block. The 193 timestamp can be compared with the timestamp of the packet that 194 arrived in the same order through a monitoring point at a 195 downstream component of the SFC to compute packet delay. Because 196 timestamps collected based on the order of arrival, this method is 197 sensitive to packet loss and re-ordering of packets 199 o Average Packet Delay calculation: an average delay is calculated 200 by considering the average arrival time of the packets within a 201 single block. A component of the SFC may collect timestamps for 202 each packet received within a single block. Average of the 203 timestamp is the sum of all the timestamps divided by the total 204 number of packets received. Then the difference between averages 205 calculated at two monitoring points is the average packet delay on 206 that segment. This method is robust to out of order packets and 207 also to packet loss (only a small error is introduced). This 208 method only provides a single metric for the duration of the 209 block, and it doesn't give the minimum and maximum delay values. 210 Highly optimized implementation of the method can reduce the 211 duration of the block and thus overcome the limitation. 213 4.2. Multiplexed Mark Enabled Measurement 215 There is also a scheme that method allows measurement of minimum and 216 maximum delays for the monitored flow using a single marking flag. 217 This methodology is described in 218 [I-D.mizrahi-ippm-compact-alternate-marking]. The concept is that in 219 the middle of each block of packets with a certain value of the M 220 flag, a single packet has the M flag inverted. So, by examining the 221 stream, the packets with the inverted bit can be easily identified 222 and employed for delay measurement. This variation of AMM is 223 advantageous because it requires only one bit from each packet, and 224 such bits are always in short supply. 226 4.3. Residence Time Measurement with the Alternate Marking Method 228 Residence time is the variable part of the propagation delay that a 229 packet experiences while traversing a network, e.g., SFC. Residence 230 Time over an SFC is the sum of the nodal residence times, i.e., 231 periods that the packet spent in each of SFFs that compose the SFC. 232 The nodal residence time in SFC itself is the sum of sub-nodal 233 residence times that the packet spent in each of SFs that are part of 234 the given SFC and are mapped to the SFF. The residence time and 235 deviation of the residence time metrics may include any combination 236 of minimum, maximum, values over measurement period, as well as mean, 237 median, percentile. These metrics may be used to evaluate the 238 performance of the SFC and its elements before and during its 239 operation. 241 Use of the specially marked packets simplifies residence time 242 measurement and correlation of the measured metrics over the E2E SFC. 243 For example, AMM may be used as described in Section 4.2 to identify 244 packets in the data flow to be used to measure the residence time. 245 The nodal and sub-nodal residence time metrics can be locally 246 calculated and then collected using either in-band or out-band OAM 247 mechanisms. 249 5. IANA Considerations 251 5.1. Mark Field in NSH Base Header 253 This document requests IANA to allocate the one-bit field from NSH 254 Base Header Bits [RFC8300] as the Mark field of NSH as the following: 256 +--------------+-------------+---------------+ 257 | Bit Position | Description | Reference | 258 +--------------+-------------+---------------+ 259 | TBA | Mark field | This document | 260 +--------------+-------------+---------------+ 262 Table 1: Mark field of SFC NSH 264 6. Security Considerations 266 This document defines the use of AMM in an SFC domain and thus all 267 security considerations specific to SFC discussed in [RFC7665] and 268 [RFC8300] are applicable. By introducing AMM into SFC environment it 269 inherits all seurity considerations discussed in [RFC8321]. A new 270 Mark flag is defined in this specification to be used by AMM. 271 Processing of AMM does require additional computational resources and 272 creates certain amount of state information of per AMM flow 273 perfromance metrics. An implementation MUST provide control over the 274 number of concurrent AMM flows that a node process. 276 7. Acknowledgment 278 TBD 280 8. References 281 8.1. Normative References 283 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 284 Requirement Levels", BCP 14, RFC 2119, 285 DOI 10.17487/RFC2119, March 1997, 286 . 288 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 289 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 290 May 2017, . 292 [RFC8300] Quinn, P., Ed., Elzur, U., Ed., and C. Pignataro, Ed., 293 "Network Service Header (NSH)", RFC 8300, 294 DOI 10.17487/RFC8300, January 2018, 295 . 297 8.2. Informative References 299 [I-D.ietf-sfc-ioam-nsh] 300 Brockners, F. and S. Bhandari, "Network Service Header 301 (NSH) Encapsulation for In-situ OAM (IOAM) Data", draft- 302 ietf-sfc-ioam-nsh-04 (work in progress), June 2020. 304 [I-D.ietf-sfc-oam-framework] 305 Aldrin, S., Pignataro, C., Nainar, N., Krishnan, R., and 306 A. Ghanwani, "Service Function Chaining (SFC) Operations, 307 Administration and Maintenance (OAM) Framework", draft- 308 ietf-sfc-oam-framework-15 (work in progress), May 2020. 310 [I-D.mizrahi-ippm-compact-alternate-marking] 311 Mizrahi, T., Arad, C., Fioccola, G., Cociglio, M., Chen, 312 M., Zheng, L., and G. Mirsky, "Compact Alternate Marking 313 Methods for Passive and Hybrid Performance Monitoring", 314 draft-mizrahi-ippm-compact-alternate-marking-05 (work in 315 progress), July 2019. 317 [RFC7665] Halpern, J., Ed. and C. Pignataro, Ed., "Service Function 318 Chaining (SFC) Architecture", RFC 7665, 319 DOI 10.17487/RFC7665, October 2015, 320 . 322 [RFC7799] Morton, A., "Active and Passive Metrics and Methods (with 323 Hybrid Types In-Between)", RFC 7799, DOI 10.17487/RFC7799, 324 May 2016, . 326 [RFC8321] Fioccola, G., Ed., Capello, A., Cociglio, M., Castaldelli, 327 L., Chen, M., Zheng, L., Mirsky, G., and T. Mizrahi, 328 "Alternate-Marking Method for Passive and Hybrid 329 Performance Monitoring", RFC 8321, DOI 10.17487/RFC8321, 330 January 2018, . 332 Authors' Addresses 334 Greg Mirsky 335 ZTE Corp. 337 Email: gregimirsky@gmail.com 339 Giuseppe Fioccola 340 Huawei Technologies 342 Email: giuseppe.fioccola@huawei.com 344 Tal Mizrahi 345 Huawei Network.IO Innovation Lab 346 Israel 348 Email: tal.mizrahi.phd@gmail.com