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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group C. Filsfils 3 Internet-Draft D. Dukes, Ed. 4 Intended status: Informational Cisco Systems, Inc. 5 Expires: January 28, 2021 K. Patel 6 Arrcus, Inc. 7 July 27, 2020 9 Analysis Framework For Extensions of SRv6 Encapsulation 10 draft-filsfils-spring-analysis-fmwk-ext-srv6-encap-01 12 Abstract 14 This document provides a framework for analysis of multiple proposals 15 to extend SRv6 encapsulation with the objective of minimizing 16 encapsulation size or leveraging legacy equipment. It defines 17 relevant metrics to evaluate each proposal. 19 Requirements Language 21 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 22 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 23 document are to be interpreted as described in RFC 2119 [RFC2119]. 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 28, 2021. 42 Copyright Notice 44 Copyright (c) 2020 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. Metrics . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 61 2.1. Compliance . . . . . . . . . . . . . . . . . . . . . . . 3 62 2.2. Data Plane Efficiency . . . . . . . . . . . . . . . . . . 4 63 2.3. State Efficiency . . . . . . . . . . . . . . . . . . . . 4 64 2.4. Encapsulation Size . . . . . . . . . . . . . . . . . . . 4 65 3. Variables For Metrics . . . . . . . . . . . . . . . . . . . . 4 66 4. Analysis of Proposals . . . . . . . . . . . . . . . . . . . . 5 67 5. Normative References . . . . . . . . . . . . . . . . . . . . 5 68 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 70 1. Introduction 72 Traffic traversing an SR domain is encapsulated in an outer IPv6 73 header with an optional Segment Routing Header (SRH) for its journey 74 through the SR domain [I-D.ietf-6man-segment-routing-header]. 76 This document provides a framework for analysis of multiple proposals 77 to extend SRv6 encapsulation with the objective of minimizing 78 encapsulation size or leveraging legacy equipment. It defines 79 relevant metrics to evaluate each proposal. 81 Future revisions will evaluate and document the metrics for each 82 proposal, compare them and draw conclusions. 84 2. Metrics 86 Metrics are identified as metric:score. Metric is the abbreviation 87 of the metric name, and score is an integer reporting its evaluation. 88 A proposal with a metric (M) and score of zero is represented as M:0. 90 A score may vary based on the number and type of instructions in a 91 segment list. Three types of segments are considered: T for 92 topological, S for service, and V for VPN. 94 A proposal with a metric (M), computed for a segment list of 5 95 topological segments followed by 1 VPN segment, with a score of 10 is 96 represented as M(5T.1V):10. 98 A score may vary based on node parameters. Three parameters are 99 considered: N the number of nodes in the network, I the number of IGP 100 algorithms [I-D.ietf-lsr-flex-algo] configured at the node, and A the 101 number of adjacency SIDs configured at the node. 103 A proposal with metric (M), computed for a node in a network of 100 104 nodes with 1 IGP algorithm and 5 adjacency SIDs configured at the 105 node, with a score of 10 is represented by M(100N.1I.5A):10. 107 2.1. Compliance 109 The compliance metric (C) records how aligned a proposal is with the 110 SRv6 solution. 112 o C.RFC8402: compliance with [RFC8402] 114 o C.SRH: compliance with [I-D.ietf-6man-segment-routing-header] 116 o C.PGM: compliance with [I-D.ietf-spring-srv6-network-programming] 118 o C.IGP: compliance with [I-D.ietf-lsr-isis-srv6-extensions] 120 o C.BGP: compliance with [I-D.ietf-bess-srv6-services] 122 o C.POL: compliance with [I-D.ietf-spring-segment-routing-policy] 124 o C.BLS: compliance with [I-D.ietf-idr-bgpls-srv6-ext] 126 o C.SVC: compliance with [I-D.ietf-spring-sr-service-programming] 128 o C.OAM: compliance with [I-D.ietf-6man-spring-srv6-oam] 130 Each of the above metrics are assigned a compliance value: 132 o 10: complies with the specification 134 o 5: extends the specification 136 o 0: redefines the specification 138 C.TOT is the sum of all C.* metrics listed above. It provides an 139 overall assessment of the proposal's alignment with the SRv6 RFCs and 140 working group drafts. 142 2.2. Data Plane Efficiency 144 The data plane efficiency metric (D) records the data plane 145 forwarding efficiency of the proposed solution. Two separate metrics 146 are used: 148 o D.PRS(segment list): worst-case number of headers parsed during 149 processing of the segment list. 151 o D.LKU(segment list): worst-case number of FIB lookups during 152 processing of the segment list. 154 2.3. State Efficiency 156 The state efficiency metric (S) records the number of additional FIB 157 entries (states) required by the proposed solution. 159 o S(node parameters): the number of additional FIB entries for a 160 node, given a set of parameters. 162 2.4. Encapsulation Size 164 The encapsulation size metric (E) records the number of bytes 165 required for the proposals 167 o E(segment list): the number of bytes required to encapsulate a 168 packet traversing the SR domain with segment list applied at an SR 169 source node. Specifically, the number of bytes from the beginning 170 of the encapsulating IPv6 header to the beginning of the packet 171 traversing the SR domain, including any and all headers in 172 between. 174 3. Variables For Metrics 176 For the E, D.PRS, D.LKU metrics the following segment lists are used 177 during analysis. 179 o 5T.1V 181 o 10T.1V 183 o 15T.1V 185 o 5T.1S.5T.1V 187 o 4T.1S.4T.1S.4T.1V 189 This list may be updated in subsequent revisions of this document. 191 For the S metric the following node parameters are used in analysis. 193 o 1500N.2I.100A 195 This list may be updated in subsequent revisions of this document. 197 4. Analysis of Proposals 199 To be completed in subsequent revisions of this document. 201 5. Normative References 203 [I-D.ietf-6man-segment-routing-header] 204 Filsfils, C., Dukes, D., Previdi, S., Leddy, J., 205 Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header 206 (SRH)", draft-ietf-6man-segment-routing-header-26 (work in 207 progress), October 2019. 209 [I-D.ietf-6man-spring-srv6-oam] 210 Ali, Z., Filsfils, C., Matsushima, S., Voyer, D., and M. 211 Chen, "Operations, Administration, and Maintenance (OAM) 212 in Segment Routing Networks with IPv6 Data plane (SRv6)", 213 draft-ietf-6man-spring-srv6-oam-07 (work in progress), 214 July 2020. 216 [I-D.ietf-bess-srv6-services] 217 Dawra, G., Filsfils, C., Raszuk, R., Decraene, B., Zhuang, 218 S., and J. Rabadan, "SRv6 BGP based Overlay services", 219 draft-ietf-bess-srv6-services-03 (work in progress), July 220 2020. 222 [I-D.ietf-idr-bgpls-srv6-ext] 223 Dawra, G., Filsfils, C., Talaulikar, K., Chen, M., 224 daniel.bernier@bell.ca, d., and B. Decraene, "BGP Link 225 State Extensions for SRv6", draft-ietf-idr-bgpls- 226 srv6-ext-03 (work in progress), July 2020. 228 [I-D.ietf-lsr-flex-algo] 229 Psenak, P., Hegde, S., Filsfils, C., Talaulikar, K., and 230 A. Gulko, "IGP Flexible Algorithm", draft-ietf-lsr-flex- 231 algo-08 (work in progress), July 2020. 233 [I-D.ietf-lsr-isis-srv6-extensions] 234 Psenak, P., Filsfils, C., Bashandy, A., Decraene, B., and 235 Z. Hu, "IS-IS Extension to Support Segment Routing over 236 IPv6 Dataplane", draft-ietf-lsr-isis-srv6-extensions-08 237 (work in progress), April 2020. 239 [I-D.ietf-spring-segment-routing-policy] 240 Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and 241 P. Mattes, "Segment Routing Policy Architecture", draft- 242 ietf-spring-segment-routing-policy-08 (work in progress), 243 July 2020. 245 [I-D.ietf-spring-sr-service-programming] 246 Clad, F., Xu, X., Filsfils, C., daniel.bernier@bell.ca, 247 d., Li, C., Decraene, B., Ma, S., Yadlapalli, C., 248 Henderickx, W., and S. Salsano, "Service Programming with 249 Segment Routing", draft-ietf-spring-sr-service- 250 programming-02 (work in progress), March 2020. 252 [I-D.ietf-spring-srv6-network-programming] 253 Filsfils, C., Camarillo, P., Leddy, J., Voyer, D., 254 Matsushima, S., and Z. Li, "SRv6 Network Programming", 255 draft-ietf-spring-srv6-network-programming-16 (work in 256 progress), June 2020. 258 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 259 Requirement Levels", BCP 14, RFC 2119, 260 DOI 10.17487/RFC2119, March 1997, 261 . 263 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., 264 Decraene, B., Litkowski, S., and R. Shakir, "Segment 265 Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, 266 July 2018, . 268 Authors' Addresses 270 Clarence Filsfils 271 Cisco Systems, Inc. 272 Belgium 274 Email: cfilsfil@cisco.com 276 Darren Dukes (editor) 277 Cisco Systems, Inc. 278 Ottawa 279 Canada 281 Email: ddukes@cisco.com 282 Keyur Patel 283 Arrcus, Inc. 284 USA 286 Email: keyur@arrcus.com