idnits 2.17.1 draft-li-idr-bgpls-sr-policy-composite-path-02.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (7 March 2022) is 753 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-19) exists of draft-ietf-idr-te-lsp-distribution-16 == Outdated reference: A later version (-22) exists of draft-ietf-spring-segment-routing-policy-19 -- Obsolete informational reference (is this intentional?): RFC 7752 (Obsoleted by RFC 9552) Summary: 0 errors (**), 0 flaws (~~), 3 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group H. Li 3 Internet-Draft M. Chen 4 Intended status: Standards Track C. Lin 5 Expires: 8 September 2022 New H3C Technologies 6 W. Jiang 7 W. Cheng 8 China Mobile 9 7 March 2022 11 Signaling Composite Candidate Path of SR Policy using BGP-LS 12 draft-li-idr-bgpls-sr-policy-composite-path-02 14 Abstract 16 Segment Routing is a source routing paradigm that explicitly 17 indicates the forwarding path for packets at the ingress node. An SR 18 Policy is associated with one or more candidate paths, and each 19 candidate path is either dynamic, explicit or composite. This 20 document specifies the extensions to BGP Link State (BGP-LS) to carry 21 composite candidate path information in the advertisement of an SR 22 policy. 24 Status of This Memo 26 This Internet-Draft is submitted in full conformance with the 27 provisions of BCP 78 and BCP 79. 29 Internet-Drafts are working documents of the Internet Engineering 30 Task Force (IETF). Note that other groups may also distribute 31 working documents as Internet-Drafts. The list of current Internet- 32 Drafts is at https://datatracker.ietf.org/drafts/current/. 34 Internet-Drafts are draft documents valid for a maximum of six months 35 and may be updated, replaced, or obsoleted by other documents at any 36 time. It is inappropriate to use Internet-Drafts as reference 37 material or to cite them other than as "work in progress." 39 This Internet-Draft will expire on 8 September 2022. 41 Copyright Notice 43 Copyright (c) 2022 IETF Trust and the persons identified as the 44 document authors. All rights reserved. 46 This document is subject to BCP 78 and the IETF Trust's Legal 47 Provisions Relating to IETF Documents (https://trustee.ietf.org/ 48 license-info) in effect on the date of publication of this document. 49 Please review these documents carefully, as they describe your rights 50 and restrictions with respect to this document. Code Components 51 extracted from this document must include Revised BSD License text as 52 described in Section 4.e of the Trust Legal Provisions and are 53 provided without warranty as described in the Revised BSD License. 55 Table of Contents 57 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 58 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 59 3. BGP-LS Extensions for Composite Candidate Path . . . . . . . 3 60 3.1. Constituent SR Policy TLV . . . . . . . . . . . . . . . . 3 61 4. Operations . . . . . . . . . . . . . . . . . . . . . . . . . 4 62 5. Security Considerations . . . . . . . . . . . . . . . . . . . 5 63 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 64 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 65 7.1. Normative References . . . . . . . . . . . . . . . . . . 5 66 7.2. Informative References . . . . . . . . . . . . . . . . . 6 67 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 69 1. Introduction 71 As described in [RFC7752], BGP Link State (BGP-LS) provides a 72 mechanism by which link-state and TE information can be collected 73 from networks and shared with external components using the BGP 74 routing protocol. 76 Segment routing (SR) [RFC8402] is a source routing paradigm that 77 explicitly indicates the forwarding path for packets at the ingress 78 node. The ingress node steers packets into a specific path according 79 to the Segment Routing Policy (SR Policy) as defined in 80 [I-D.ietf-spring-segment-routing-policy]. 82 An SR Policy is associated with one or more candidate paths. A 83 composite candidate path acts as a container for grouping of SR 84 Policies. As described in section 2.2 in 85 [I-D.ietf-spring-segment-routing-policy], the composite candidate 86 path construct enables combination of SR Policies, each with explicit 87 candidate paths and/or dynamic candidate paths with potentially 88 different optimization objectives and constraints, for a load- 89 balanced steering of packet flows over its constituent SR Policies. 91 [I-D.jiang-spring-sr-policy-group-use-cases] describes some use cases 92 for SR policy group composite candidate path. 94 [I-D.ietf-idr-te-lsp-distribution] describes a mechanism to collect 95 the SR policy information that is locally available in a node and 96 advertise it into BGP-LS updates. This document extends it to 97 provide some extra information to carry composite candidate path 98 information in the BGP-LS advertisement. 100 2. Terminology 102 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 103 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 104 "OPTIONAL" in this document are to be interpreted as described in BCP 105 14 [RFC2119] [RFC8174] when, and only when, they appear in all 106 capitals, as shown here. 108 3. BGP-LS Extensions for Composite Candidate Path 110 [RFC7752] defines the BGP-LS NLRI that can be a Node NLRI, a Link 111 NLRI or a Prefix NLRI. The corresponding BGP-LS attribute is a Node 112 Attribute, a Link Attribute or a Prefix Attribute. 113 [I-D.ietf-idr-te-lsp-distribution] describes a mechanism to collect 114 the SR Policy information that is locally available in a node and 115 advertise it into BGP Link State (BGP-LS) updates. This section 116 defines a new sub-TLV which is carried in the optional non-transitive 117 BGP Attribute "LINK_STATE Attribute" defined in [RFC7752]. 119 3.1. Constituent SR Policy TLV 121 Segment Routing Policy (SR Policy) architecture is specified in 122 [I-D.ietf-spring-segment-routing-policy]. A SR Policy can comprise 123 of one or more candidate paths, and each candidate path is either 124 dynamic, explicit or composite. A composite candidate path can 125 comprise of one or more constituent SR policies. The endpoints of 126 the constituent SR Policies and the parent SR Policy MUST be 127 identical, and the colors of each of the constituent SR Policies and 128 the parent SR Policy MUST be different. 130 The Constituent SR Policy TLV is used to report the constituent SR 131 policy(s) of a composite candidate path. The TLV has following 132 format: 134 0 1 2 3 135 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 1 136 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 137 | Type | Length | 138 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 139 | RESERVED | 140 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 141 | Color | 142 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 143 | Weight | 144 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 145 | Sub-TLVs (variable) // 146 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 148 where: 150 * Type: to be assigned by IANA. 152 * Length: the total length of the value field not including Type and 153 Length fields. 155 * Reserved: 32 bits reserved and MUST be set to 0 on transmission 156 and MUST be ignored on receipt. 158 * Color: 4 octets that indicates the color of the constituent SR 159 Policy. 161 * Weight: 4 octet field that indicates the weight associated with 162 the SID-List for weighted load-balancing. Refer Section 2.2 and 163 2.11 of [I-D.ietf-spring-segment-routing-policy]. 165 * Sub-TLVs: no sub-TLV is currently defined. 167 4. Operations 169 The document does not bring new operation beyond the description of 170 operations defined in [RFC7752] and 171 [I-D.ietf-idr-te-lsp-distribution]. The existing operations defined 172 in [RFC7752] and [I-D.ietf-idr-te-lsp-distribution] can apply to this 173 document directly. 175 Typically but not limit to, the BGP-LS messages carring composite 176 candidate path information along with the SR policy are distributed 177 to a controller. 179 After configuration, the composite candidate path information will be 180 advertised by BGP update messages. The operation of advertisement is 181 the same as defined in [RFC7752] and 182 [I-D.ietf-idr-te-lsp-distribution], as well as the receiption. 184 5. Security Considerations 186 Procedures and protocol extensions defined in this document do not 187 affect the security considerations discussed in 188 [I-D.ietf-idr-te-lsp-distribution]. 190 6. IANA Considerations 192 This document defines a new TLV in the BGP-LS Link Descriptor and 193 Attribute TLVs: 195 +=======+===========================+===============+ 196 | Value | Description | Reference | 197 +=======+===========================+===============+ 198 | TBA | Constituent SR Policy TLV | This document | 199 +-------+---------------------------+---------------+ 201 Table 1 203 7. References 205 7.1. Normative References 207 [I-D.ietf-idr-te-lsp-distribution] 208 Previdi, S., Talaulikar, K., Dong, J., Chen, M., Gredler, 209 H., and J. Tantsura, "Distribution of Traffic Engineering 210 (TE) Policies and State using BGP-LS", Work in Progress, 211 Internet-Draft, draft-ietf-idr-te-lsp-distribution-16, 22 212 October 2021, . 215 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 216 Requirement Levels", BCP 14, RFC 2119, 217 DOI 10.17487/RFC2119, March 1997, 218 . 220 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 221 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 222 May 2017, . 224 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., 225 Decraene, B., Litkowski, S., and R. Shakir, "Segment 226 Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, 227 July 2018, . 229 7.2. Informative References 231 [I-D.ietf-spring-segment-routing-policy] 232 Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and 233 P. Mattes, "Segment Routing Policy Architecture", Work in 234 Progress, Internet-Draft, draft-ietf-spring-segment- 235 routing-policy-19, 5 March 2022, . 239 [I-D.jiang-spring-sr-policy-group-use-cases] 240 Jiang, W., Cheng, W., Lin, C., and Y. Qiu, "Segment 241 Routing Policy Architecture", Work in Progress, Internet- 242 Draft, draft-jiang-spring-sr-policy-group-use-cases-00, 7 243 March 2022, . 246 [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and 247 S. Ray, "North-Bound Distribution of Link-State and 248 Traffic Engineering (TE) Information Using BGP", RFC 7752, 249 DOI 10.17487/RFC7752, March 2016, 250 . 252 Authors' Addresses 254 Hao Li 255 New H3C Technologies 256 Email: lihao@h3c.com 258 Mengxiao Chen 259 New H3C Technologies 260 Email: chen.mengxiao@h3c.com 262 Changwang Lin 263 New H3C Technologies 264 Email: linchangwang.04414@h3c.com 266 Wenying Jiang 267 China Mobile 268 Email: jiangwenying@chinamobile.com 269 Weiqiang Cheng 270 China Mobile 271 Email: chengweiqiang@chinamobile.com