idnits 2.17.1 draft-li-idr-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 : ---------------------------------------------------------------------------- == There are 1 instance of lines with non-RFC6890-compliant IPv4 addresses in the document. If these are example addresses, they should be changed. 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 782 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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-26) exists of draft-ietf-idr-segment-routing-te-policy-15 == Outdated reference: A later version (-22) exists of draft-ietf-spring-segment-routing-policy-19 Summary: 0 errors (**), 0 flaws (~~), 4 warnings (==), 1 comment (--). 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 BGP Extensions of SR Policy for Composite Candidate Path 12 draft-li-idr-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. A candidate 19 path is either dynamic, explicit or composite. This document defines 20 extensions to BGP to distribute SR policies carrying composite 21 candidate path information. So that composite candidate paths can be 22 installed when the SR policy is applied. 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. Constituent SR Policy Attributes in SR Policy . . . . . . . . 3 60 3.1. Constituent SR Policy Sub-TLV . . . . . . . . . . . . . . 4 61 4. Operations . . . . . . . . . . . . . . . . . . . . . . . . . 5 62 5. Security Considerations . . . . . . . . . . . . . . . . . . . 5 63 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 64 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 65 7.1. Normative References . . . . . . . . . . . . . . . . . . 6 66 7.2. Informative References . . . . . . . . . . . . . . . . . 6 67 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 69 1. Introduction 71 Segment routing (SR) [RFC8402] is a source routing paradigm that 72 explicitly indicates the forwarding path for packets at the ingress 73 node. The ingress node steers packets into a specific path according 74 to the Segment Routing Policy (SR Policy) as defined in 75 [I-D.ietf-spring-segment-routing-policy]. In order to distribute SR 76 policies to the headend, [I-D.ietf-idr-segment-routing-te-policy] 77 specifies a mechanism by using BGP. 79 An SR Policy is associated with one or more candidate paths. A 80 composite candidate path acts as a container for grouping of SR 81 Policies. As described in section 2.2 in 82 [I-D.ietf-spring-segment-routing-policy], the composite candidate 83 path construct enables combination of SR Policies, each with explicit 84 candidate paths and/or dynamic candidate paths with potentially 85 different optimization objectives and constraints, for a load- 86 balanced steering of packet flows over its constituent SR Policies. 88 [I-D.jiang-spring-sr-policy-group-use-cases] describes some use cases 89 for SR policy group composite candidate path. 91 This document defines extensions to Border Gateway Protocol (BGP) to 92 distribute SR policies carrying composite candidate path information. 93 So that composite candidate paths can be installed when the SR policy 94 is applied. 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. Constituent SR Policy Attributes in SR Policy 106 As defined in [I-D.ietf-idr-segment-routing-te-policy], the SR policy 107 encoding structure is as follows: 109 SR Policy SAFI NLRI: 110 Attributes: 111 Tunnel Encaps Attribute (23) 112 Tunnel Type: SR Policy 113 Binding SID 114 SRv6 Binding SID 115 Preference 116 Priority 117 Policy Name 118 Policy Candidate Path Name 119 Explicit NULL Label Policy (ENLP) 120 Segment List 121 Weight 122 Segment 123 Segment 124 ... 125 ... 127 As described in section 2.2 in 128 [I-D.ietf-spring-segment-routing-policy], the endpoints of the 129 constituent SR Policies and the parent SR Policy MUST be identical, 130 and the colors of each of the constituent SR Policies and the parent 131 SR Policy MUST be different. Therefore a constituent SR Policy is 132 referenced only by color in the composite candidate path since its 133 headend and endpoint are identical to the parent SR policy. 135 SR policy with composite candidate path information is expressed as 136 below: 138 SR Policy SAFI NLRI: 139 Attributes: 140 Tunnel Encaps Attribute (23) 141 Tunnel Type: SR Policy 142 Binding SID 143 SRv6 Binding SID 144 Preference 145 Priority 146 Policy Name 147 Policy Candidate Path Name 148 Explicit NULL Label Policy (ENLP) 149 Segment List 150 Weight 151 Segment 152 Segment 153 ... 154 Constituent SR Policy 155 Weight 156 ... 158 3.1. Constituent SR Policy Sub-TLV 160 The Constituent SR Policy sub-TLV encodes a single composite path 161 towards the endpoint. The Constituent SR Policy sub-TLV is an 162 optional sub-TLV of BGP Tunnel Encapsulation Attribute, and MAY 163 appear multiple times in the SR Policy encoding. The ordering of 164 Constituent SR Policy sub-TLVs does not matter. The Constituent SR 165 Policy sub-TLV MAY contain a Weight sub-TLV. 167 Since a candidate path is either dynamic, explicit or composite, the 168 Constituent SR Policy sub-TLV and the Segment List sub-TLV SHOULD NOT 169 appear in the same candidate path. 171 The Constituent SR Policy sub-TLV has the following format: 173 0 1 2 3 174 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 1 175 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 176 | Type | Length | RESERVED | 177 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 178 | Color | 179 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 180 | sub-TLVs | 181 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 183 where: 185 * Type: to be assigned by IANA. 187 * Length: the total length of the value field not including Type and 188 Length fields. 190 * RESERVED: 2 octet of reserved bits. SHOULD be set to zero on 191 transmission and MUST be ignored on receipt. 193 * Color: 4-octet value identifying the constituent SR policy. 195 * sub-TLVs currently defined: 197 - An optional single Weight sub-TLV which is defined in section 198 2.4.4.1 in [I-D.ietf-idr-segment-routing-te-policy]. According 199 to [I-D.ietf-spring-segment-routing-policy], the fraction of 200 flows steered into each constituent SR Policy is equal to the 201 relative weight of each constituent SR Policy. 203 4. Operations 205 The document does not bring new operation beyond the description of 206 operations defined in [I-D.ietf-idr-segment-routing-te-policy]. The 207 existing operations defined in 208 [I-D.ietf-idr-segment-routing-te-policy] can apply to this document 209 directly. 211 Typically but not limit to, the SR policies carrying composite 212 candidate path information are configured by a controller. 214 After configuration, the SR policies carrying path composite 215 candidate path information will be advertised by BGP update messages. 216 The operation of advertisement is the same as defined in 217 [I-D.ietf-idr-segment-routing-te-policy], as well as the receiption. 219 5. Security Considerations 221 Procedures and protocol extensions defined in this document do not 222 affect the security considerations discussed in 223 [I-D.ietf-idr-segment-routing-te-policy]. 225 6. IANA Considerations 227 This document defines a new Sub-TLV in registries "SR Policy List 228 Sub-TLVs" [I-D.ietf-idr-segment-routing-te-policy]: 230 +=======+===============================+===============+ 231 | Value | Description | Reference | 232 +=======+===============================+===============+ 233 | TBA | Constituent SR Policy Sub-TLV | This document | 234 +-------+-------------------------------+---------------+ 236 Table 1 238 7. References 240 7.1. Normative References 242 [I-D.ietf-idr-segment-routing-te-policy] 243 Previdi, S., Filsfils, C., Talaulikar, K., Mattes, P., 244 Rosen, E., Jain, D., and S. Lin, "Advertising Segment 245 Routing Policies in BGP", Work in Progress, Internet- 246 Draft, draft-ietf-idr-segment-routing-te-policy-15, 5 247 March 2022, . 250 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 251 Requirement Levels", BCP 14, RFC 2119, 252 DOI 10.17487/RFC2119, March 1997, 253 . 255 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 256 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 257 May 2017, . 259 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., 260 Decraene, B., Litkowski, S., and R. Shakir, "Segment 261 Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, 262 July 2018, . 264 7.2. Informative References 266 [I-D.ietf-spring-segment-routing-policy] 267 Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and 268 P. Mattes, "Segment Routing Policy Architecture", Work in 269 Progress, Internet-Draft, draft-ietf-spring-segment- 270 routing-policy-19, 5 March 2022, . 274 [I-D.jiang-spring-sr-policy-group-use-cases] 275 Jiang, W., Cheng, W., Lin, C., and Y. Qiu, "Segment 276 Routing Policy Architecture", Work in Progress, Internet- 277 Draft, draft-jiang-spring-sr-policy-group-use-cases-00, 7 278 March 2022, . 281 Authors' Addresses 283 Hao Li 284 New H3C Technologies 285 Email: lihao@h3c.com 287 Mengxiao Chen 288 New H3C Technologies 289 Email: chen.mengxiao@h3c.com 291 Changwang Lin 292 New H3C Technologies 293 Email: linchangwang.04414@h3c.com 295 Wenying Jiang 296 China Mobile 297 Email: jiangwenying@chinamobile.com 299 Weiqiang Cheng 300 China Mobile 301 Email: chengweiqiang@chinamobile.com