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Linda 4 Intended status: Standards Track Futurewei Technologies 5 Expires: December 2, 2021 May 31, 2021 7 In-band Edge-to-Edge Round Trip Time Measurement 8 draft-song-ippm-inband-e2e-rtt-measurement-01 10 Abstract 12 This draft describes a lightweight in-band edge-to-edge network round 13 trip time measurement architecture and suggests implementations. By 14 augmenting the IOAM E2E option header, the process can be fully done 15 in data plane without needing to involve the control plane to 16 maintain any states. 18 Requirements Language 20 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 21 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 22 "OPTIONAL" in this document are to be interpreted as described in BCP 23 14 [RFC2119][RFC8174] when, and only when, they appear in all 24 capitals, as shown here. 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 2, 2021. 43 Copyright Notice 45 Copyright (c) 2021 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. In-band E2E RTT Measurement Architecture . . . . . . . . . . 3 62 3. Implementation Considerations . . . . . . . . . . . . . . . . 4 63 4. Security Considerations . . . . . . . . . . . . . . . . . . . 5 64 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 65 6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 6 66 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6 67 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 68 8.1. Normative References . . . . . . . . . . . . . . . . . . 6 69 8.2. Informative References . . . . . . . . . . . . . . . . . 6 70 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 72 1. Introduction 74 In-network service-based traffic engineering or load balancing needs 75 to monitor particular flows' edge-to-edge performance, such as round 76 trip time (RTT), in the operator's network domain. The host-based 77 ping using ICMPv6 [RFC4443] is of no use because it is usually beyond 78 the access of network operators. The router-based ping, as an active 79 measurement approach, cannot reflect the real performance of the 80 specific flows under scrutiny. This is also true for the other 81 active measurement approaches such as TWAMP [RFC5357]. 83 In-situ OAM (IOAM) [I-D.ietf-ippm-ioam-data] supports in-band flow- 84 based performance measurement. However, on the one hand, the IOAM 85 trace option is too heavy for the applications which do not care 86 about the per-hop performance; on the other hand, the IOAM E2E option 87 only supports the one-way measurement. 89 Alternate Marking(AM) [RFC8321], mainly designed for one-way 90 measurement, can be used to measure the two-way edge-to-edge delay if 91 both edges initiate a one-way measurement session. However, AM's 92 measurement interval needs to be large enough to avoid the 93 measurement ambiguity, and it requires both edges to conduct the 94 measurements and export results to a controller. 96 We need a lightweight in-band flow RTT measurement method. 97 "Lightweight" means the extra header overhead is low, and the extra 98 network processing overhead is also low. A network operator should 99 be able to pick a flow to monitor and get find-grained per-packet RTT 100 measurement for edge to edge. Moreover, the method should be 101 stateless and does not need a control plane to maintain sessions. 102 Depending on the application scenario and the network domain scope, 103 the edge can extend to the host, the network interface card (NIC), or 104 the network switch or router. To this end, we propose an in-band 105 edge-to-edge RTT measurement method and suggest the implementation 106 approaches. 108 Such measurement only reflects the network delay for a flow but 109 excludes the application layer delay incurred by server or client. 111 2. In-band E2E RTT Measurement Architecture 113 The measurement architecture is shown in Figure 1. The controller, 114 either on a remote machine or on the edge node's control plane, 115 configures the ingress edge node to measure some flow's RTT between 116 the ingress edge and the egress edge. The ingress edge node uses ACL 117 to filter the flow packets and, at given interval or probability, add 118 the timestamp and the other metadata to the selected packets. The 119 egress edge, after capturing the data, either piggyback the data on a 120 reverse flow packet, or generate a feedback packet carrying the data 121 back to the ingress edge node. Once the ingress edge node receives 122 the feedback data, it sends the data along with the current timestamp 123 to the controller. The controller can then calculate the flow RTT 124 and react with followup actions. 126 The RTT calculation is done in the slow path, the metadata incurs 127 only small and fix header overhead, and the nodes in the domain does 128 not do any processing. All these make the measurement lightweight, 129 accurate, and have little impact to the network forwarding 130 performance. 132 +------+ 133 | | 134 |Ctrl. | 135 | | 136 +-+----+ 137 | ^ 138 Config. | | Export 139 V | 140 +------+ +----+-+ Forwarding +------+ +------+ 141 | | pkt. | +-----......------>| | pkt. | | 142 |Client+----->| Edge | | Edge +----->|Server| 143 | | | |<----......-------+ | | | 144 +------+ +------+ Feedback +------+ +------+ 146 |<-- Operator Network Domain -->| 148 Figure 1: In-band E2E RTT Measurement 150 To differentiate a feedback packet from an original packet, a flag 151 needs to be raised in the feedback. Optionally, to correlate a 152 feedback with its original packet, the original packet can also 153 include an identifier (e.g., a sequence number) which the feedback 154 packet will carry back as well. The ingress edge node can use the 155 reverse flow ID plus the identifier to pair an original packet with 156 its feedback. 158 The feedback can also include some other local data at the egress 159 edge (e.g., the egress edge node ID or the egress flow statistics) 160 other than simply reflecting the original data back. 162 3. Implementation Considerations 164 One approach to implement the in-band E2E RTT measurement is to use 165 the IOAM E2E option augmented with the feedback mechanism. Current 166 IOAM E2E option only sends one-way data from one edge to the other 167 edge. The data fields can include the ingress edge timestamp which 168 is exactly what is needed. Moreover, the data fields can also 169 include a packet sequence number used for correlating the feedback 170 packet with the original packet. However, current IOAM E2E option 171 lacks a feedback mechanism. It has no flag field reserved in its 172 current option header specification, so it is not easy to indicate 173 the feedback packets. 175 To enable the two-way measurement behavior, we need to add some 176 indicator to the IOAM E2E option header to indicate the request for a 177 feedback. We also need another indicator to tell if the current 178 packet is a feedback. 180 To support this, we can either introduce another IOAM two-way E2E 181 option while keeping the current IOAM E2E option unchanged, or simply 182 modify the current IOAM E2E option header specification to extend its 183 usage. The simplest modification is to reserve a few flag bits and 184 among them, two bits are used for the two-way measurement. One 185 possible layout is shown in Figure 2. Alternatively, the flags can 186 take several bits from the Namespace-ID field. 188 0 1 2 3 189 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 1 190 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 191 | Namespace-ID | Flags | IOAM-E2E-Type | 192 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 193 | | 194 | E2E Option data field determined by IOAM-E2E-Type | 195 | | 196 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 198 Figure 2: Modified IOAM E2E Option Header 200 The data field can carry the timestamp, the sequence number, of a 201 unique packet identifier number. Other data types can also be 202 carried to enrich the feedback information. 204 A packet can serve as both a forward packet and a feedback packet 205 when both flags are set. In this case, there are two records for 206 each data type in the data field. The forward packet's data are 207 located in front of the feedback packet's data. 209 4. Security Considerations 211 To prevent the timestamp to be maliciously altered during the packet 212 forwarding, the ingress edge can instead keep the timestamp locally 213 and only send a packet identifier (e.g., a random data). When a 214 reverse flow packet carrying the same identifier is received, the 215 current timestamp along with the saved timestamp are forwarded to the 216 controller. 218 The ingress edge node can limit the frequency of measurement to the 219 flow packets. The egress edge node can also rate limit the feedback. 220 So the potential DoS attack can be mitigated. 222 5. IANA Considerations 224 Depending on the discussion output, either a registry for a new IOAM 225 option is required or a modification to the current IOAM E2E option 226 specification is needed. 228 6. Contributors 230 TBD. 232 7. Acknowledgments 234 TBD. 236 8. References 238 8.1. Normative References 240 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 241 Requirement Levels", BCP 14, RFC 2119, 242 DOI 10.17487/RFC2119, March 1997, 243 . 245 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 246 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 247 May 2017, . 249 8.2. Informative References 251 [I-D.ietf-ippm-ioam-data] 252 Brockners, F., Bhandari, S., and T. Mizrahi, "Data Fields 253 for In-situ OAM", draft-ietf-ippm-ioam-data-12 (work in 254 progress), February 2021. 256 [RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet 257 Control Message Protocol (ICMPv6) for the Internet 258 Protocol Version 6 (IPv6) Specification", STD 89, 259 RFC 4443, DOI 10.17487/RFC4443, March 2006, 260 . 262 [RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J. 263 Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)", 264 RFC 5357, DOI 10.17487/RFC5357, October 2008, 265 . 267 [RFC8321] Fioccola, G., Ed., Capello, A., Cociglio, M., Castaldelli, 268 L., Chen, M., Zheng, L., Mirsky, G., and T. Mizrahi, 269 "Alternate-Marking Method for Passive and Hybrid 270 Performance Monitoring", RFC 8321, DOI 10.17487/RFC8321, 271 January 2018, . 273 Authors' Addresses 275 Haoyu Song 276 Futurewei Technologies 277 Santa Clara 278 USA 280 Email: haoyu.song@futurewei.com 282 Linda Dunbar 283 Futurewei Technologies 284 Plano 285 USA 287 Email: linda.dunbar@futurewei.com