idnits 2.17.1 draft-li-idr-bgpls-sr-policy-composite-path-01.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 (August 2, 2021) is 998 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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-19) exists of draft-ietf-idr-te-lsp-distribution-15 == Outdated reference: A later version (-22) exists of draft-ietf-spring-segment-routing-policy-13 -- Obsolete informational reference (is this intentional?): RFC 7752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: February 3, 2022 H3C 6 August 2, 2021 8 Signaling Composite Candidate Path of SR Policy using BGP-LS 9 draft-li-idr-bgpls-sr-policy-composite-path-01 11 Abstract 13 Segment Routing is a source routing paradigm that explicitly 14 indicates the forwarding path for packets at the ingress node. An SR 15 Policy is associated with one or more candidate paths, and each 16 candidate path is either dynamic, explicit or composite. This 17 document specifies the extensions to BGP Link State (BGP-LS) to carry 18 composite candidate path information in the advertisement of an SR 19 policy. 21 Status of This Memo 23 This Internet-Draft is submitted in full conformance with the 24 provisions of BCP 78 and BCP 79. 26 Internet-Drafts are working documents of the Internet Engineering 27 Task Force (IETF). Note that other groups may also distribute 28 working documents as Internet-Drafts. The list of current Internet- 29 Drafts is at https://datatracker.ietf.org/drafts/current/. 31 Internet-Drafts are draft documents valid for a maximum of six months 32 and may be updated, replaced, or obsoleted by other documents at any 33 time. It is inappropriate to use Internet-Drafts as reference 34 material or to cite them other than as "work in progress." 36 This Internet-Draft will expire on February 3, 2022. 38 Copyright Notice 40 Copyright (c) 2021 IETF Trust and the persons identified as the 41 document authors. All rights reserved. 43 This document is subject to BCP 78 and the IETF Trust's Legal 44 Provisions Relating to IETF Documents 45 (https://trustee.ietf.org/license-info) in effect on the date of 46 publication of this document. Please review these documents 47 carefully, as they describe your rights and restrictions with respect 48 to this document. Code Components extracted from this document must 49 include Simplified BSD License text as described in Section 4.e of 50 the Trust Legal Provisions and are provided without warranty as 51 described in the Simplified BSD License. 53 Table of Contents 55 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 56 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 57 3. BGP-LS Extensions for Composite Candidate Path . . . . . . . 3 58 3.1. Constituent SR Policy TLV . . . . . . . . . . . . . . . . 3 59 4. Operations . . . . . . . . . . . . . . . . . . . . . . . . . 4 60 5. Security Considerations . . . . . . . . . . . . . . . . . . . 4 61 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 62 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 5 63 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 64 8.1. Normative References . . . . . . . . . . . . . . . . . . 5 65 8.2. Informative References . . . . . . . . . . . . . . . . . 6 66 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 68 1. Introduction 70 As described in [RFC7752], BGP Link State (BGP-LS) provides a 71 mechanism by which link-state and TE information can be collected 72 from networks and shared with external components using the BGP 73 routing protocol. 75 Segment routing (SR) [RFC8402] is a source routing paradigm that 76 explicitly indicates the forwarding path for packets at the ingress 77 node. The ingress node steers packets into a specific path according 78 to the Segment Routing Policy (SR Policy) as defined in 79 [I-D.ietf-spring-segment-routing-policy]. 81 An SR Policy is associated with one or more candidate paths. A 82 composite candidate path acts as a container for grouping of SR 83 Policies. As described in section 2.2 in 84 [I-D.ietf-spring-segment-routing-policy], the composite candidate 85 path construct enables combination of SR Policies, each with explicit 86 candidate paths and/or dynamic candidate paths with potentially 87 different optimization objectives and constraints, for a load- 88 balanced steering of packet flows over its constituent SR Policies. 90 [I-D.ietf-idr-te-lsp-distribution] describes a mechanism to collect 91 the SR policy information that is locally available in a node and 92 advertise it into BGP-LS updates. This document extends it to 93 provide some extra information to carry composite candidate path 94 information in the BGP-LS advertisement. 96 2. Terminology 98 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 99 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 100 "OPTIONAL" in this document are to be interpreted as described in BCP 101 14 [RFC2119] [RFC8174] when, and only when, they appear in all 102 capitals, as shown here. 104 3. BGP-LS Extensions for Composite Candidate Path 106 [RFC7752] defines the BGP-LS NLRI that can be a Node NLRI, a Link 107 NLRI or a Prefix NLRI. The corresponding BGP-LS attribute is a Node 108 Attribute, a Link Attribute or a Prefix Attribute. 109 [I-D.ietf-idr-te-lsp-distribution] describes a mechanism to collect 110 the SR Policy information that is locally available in a node and 111 advertise it into BGP Link State (BGP-LS) updates. This section 112 defines a new sub-TLV which is carried in the optional non-transitive 113 BGP Attribute "LINK_STATE Attribute" defined in [RFC7752]. 115 3.1. Constituent SR Policy TLV 117 Segment Routing Policy (SR Policy) architecture is specified in 118 [I-D.ietf-spring-segment-routing-policy]. A SR Policy can comprise 119 of one or more candidate paths, and each candidate path is either 120 dynamic, explicit or composite. A composite candidate path can 121 comprise of one or more constituent SR policies. The endpoints of 122 the constituent SR Policies and the parent SR Policy MUST be 123 identical, and the colors of each of the constituent SR Policies and 124 the parent SR Policy MUST be different. 126 The Constituent SR Policy TLV is used to report the constituent SR 127 policy(s) of a composite candidate path. The TLV has following 128 format: 130 0 1 2 3 131 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 1 132 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 133 | Type | Length | 134 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 135 | RESERVED | 136 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 137 | Color | 138 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 139 | Weight | 140 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 141 | Sub-TLVs (variable) // 142 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 143 where: 145 o Type: to be assigned by IANA. 147 o Length: the total length of the value field not including Type and 148 Length fields. 150 o Reserved: 32 bits reserved and MUST be set to 0 on transmission 151 and MUST be ignored on receipt. 153 o Color: 4 octets that indicates the color of the constituent SR 154 Policy. 156 o Weight: 4 octet field that indicates the weight associated with 157 the SID-List for weighted load-balancing. Refer Section 2.2 and 158 2.11 of [I-D.ietf-spring-segment-routing-policy]. 160 o Sub-TLVs: no sub-TLV is currently defined. 162 4. Operations 164 The document does not bring new operation beyond the description of 165 operations defined in [RFC7752] and 166 [I-D.ietf-idr-te-lsp-distribution]. The existing operations defined 167 in [RFC7752] and [I-D.ietf-idr-te-lsp-distribution] can apply to this 168 document directly. 170 Typically but not limit to, the BGP-LS messages carring composite 171 candidate path information along with the SR policy are distributed 172 to a controller. 174 After configuration, the composite candidate path information will be 175 advertised by BGP update messages. The operation of advertisement is 176 the same as defined in [RFC7752] and 177 [I-D.ietf-idr-te-lsp-distribution], as well as the receiption. 179 5. Security Considerations 181 Procedures and protocol extensions defined in this document do not 182 affect the security considerations discussed in 183 [I-D.ietf-idr-te-lsp-distribution]. 185 6. IANA Considerations 187 This document defines a new TLV in the BGP-LS Link Descriptor and 188 Attribute TLVs: 190 +-------+---------------------------+---------------+ 191 | Value | Description | Reference | 192 +-------+---------------------------+---------------+ 193 | TBA | Constituent SR Policy TLV | This document | 194 +-------+---------------------------+---------------+ 196 7. Contributors 198 In addition to the authors listed on the front page, the following 199 co-authors have also contributed to this document: 201 Yuanxiang Qiu 202 H3C 203 qiuyuanxiang@h3c.com 205 Liping Yang 206 H3C 207 liping_yang@h3c.com 209 Yang Wang 210 H3C 211 wang.a.yang@h3c.com 213 8. References 215 8.1. Normative References 217 [I-D.ietf-idr-te-lsp-distribution] 218 Previdi, S., Talaulikar, K., Dong, J., Chen, M., Gredler, 219 H., and J. Tantsura, "Distribution of Traffic Engineering 220 (TE) Policies and State using BGP-LS", draft-ietf-idr-te- 221 lsp-distribution-15 (work in progress), May 2021. 223 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 224 Requirement Levels", BCP 14, RFC 2119, 225 DOI 10.17487/RFC2119, March 1997, 226 . 228 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 229 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 230 May 2017, . 232 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., 233 Decraene, B., Litkowski, S., and R. Shakir, "Segment 234 Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, 235 July 2018, . 237 8.2. Informative References 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-13 (work in progress), 243 June 2021. 245 [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and 246 S. Ray, "North-Bound Distribution of Link-State and 247 Traffic Engineering (TE) Information Using BGP", RFC 7752, 248 DOI 10.17487/RFC7752, March 2016, 249 . 251 Authors' Addresses 253 Hao Li 254 H3C 256 Email: lihao@h3c.com 258 Mengxiao Chen 259 H3C 261 Email: chen.mengxiao@h3c.com 263 Changwang Lin 264 H3C 266 Email: linchangwang.04414@h3c.com