idnits 2.17.1 draft-li-idr-sr-policy-composite-path-00.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 (February 2, 2021) is 1150 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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-26) exists of draft-ietf-idr-segment-routing-te-policy-11 == Outdated reference: A later version (-22) exists of draft-ietf-spring-segment-routing-policy-09 Summary: 0 errors (**), 0 flaws (~~), 4 warnings (==), 1 comment (--).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: August 6, 2021 H3C 6 February 2, 2021 8 BGP Extensions of SR Policy for Composite Candidate Path 9 draft-li-idr-sr-policy-composite-path-00 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. A candidate 16 path is either dynamic, explicit or composite. This document defines 17 extensions to BGP to distribute SR policies carrying composite 18 candidate path information. So that composite candidate paths can be 19 installed when the SR policy is applied. 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 August 6, 2021. 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 . . . . . . . . . . . . . . . . . . . . . . . . . 2 57 3. Constituent SR Policy Attributes in SR Policy . . . . . . . . 3 58 3.1. Constituent SR Policy Sub-TLV . . . . . . . . . . . . . . 4 59 4. Operations . . . . . . . . . . . . . . . . . . . . . . . . . 5 60 5. Security Considerations . . . . . . . . . . . . . . . . . . . 5 61 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 62 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 6 63 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 64 8.1. Normative References . . . . . . . . . . . . . . . . . . 6 65 8.2. Informative References . . . . . . . . . . . . . . . . . 6 66 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 68 1. Introduction 70 Segment routing (SR) [RFC8402] is a source routing paradigm that 71 explicitly indicates the forwarding path for packets at the ingress 72 node. The ingress node steers packets into a specific path according 73 to the Segment Routing Policy (SR Policy) as defined in 74 [I-D.ietf-spring-segment-routing-policy]. In order to distribute SR 75 policies to the headend, [I-D.ietf-idr-segment-routing-te-policy] 76 specifies a mechanism by using BGP. 78 An SR Policy is associated with one or more candidate paths. A 79 composite candidate path acts as a container for grouping of SR 80 Policies. As described in section 2.2 in 81 [I-D.ietf-spring-segment-routing-policy], the composite candidate 82 path construct enables combination of SR Policies, each with explicit 83 candidate paths and/or dynamic candidate paths with potentially 84 different optimization objectives and constraints, for a load- 85 balanced steering of packet flows over its constituent SR Policies. 87 This document defines extensions to Border Gateway Protocol (BGP) to 88 distribute SR policies carrying composite candidate path information. 89 So that composite candidate paths can be installed when the SR policy 90 is applied. 92 2. Terminology 94 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 95 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 96 "OPTIONAL" in this document are to be interpreted as described in BCP 97 14 [RFC2119] [RFC8174] when, and only when, they appear in all 98 capitals, as shown here. 100 3. Constituent SR Policy Attributes in SR Policy 102 As defined in [I-D.ietf-idr-segment-routing-te-policy], the SR policy 103 encoding structure is as follows: 105 SR Policy SAFI NLRI: 106 Attributes: 107 Tunnel Encaps Attribute (23) 108 Tunnel Type: SR Policy 109 Binding SID 110 SRv6 Binding SID 111 Preference 112 Priority 113 Policy Name 114 Policy Candidate Path Name 115 Explicit NULL Label Policy (ENLP) 116 Segment List 117 Weight 118 Segment 119 Segment 120 ... 121 ... 123 As described in section 2.2 in 124 [I-D.ietf-spring-segment-routing-policy], the endpoints of the 125 constituent SR Policies and the parent SR Policy MUST be identical, 126 and the colors of each of the constituent SR Policies and the parent 127 SR Policy MUST be different. Therefore a constituent SR Policy is 128 referenced only by color in the composite candidate path since its 129 headend and endpoint are identical to the parent SR policy. 131 SR policy with composite candidate path information is expressed as 132 below: 134 SR Policy SAFI NLRI: 135 Attributes: 136 Tunnel Encaps Attribute (23) 137 Tunnel Type: SR Policy 138 Binding SID 139 SRv6 Binding SID 140 Preference 141 Priority 142 Policy Name 143 Policy Candidate Path Name 144 Explicit NULL Label Policy (ENLP) 145 Segment List 146 Weight 147 Segment 148 Segment 149 ... 150 Constituent SR Policy 151 Weight 152 ... 154 3.1. Constituent SR Policy Sub-TLV 156 The Constituent SR Policy sub-TLV encodes a single composite path 157 towards the endpoint. The Constituent SR Policy sub-TLV is an 158 optional sub-TLV of BGP Tunnel Encapsulation Attribute, and MAY 159 appear multiple times in the SR Policy encoding. The ordering of 160 Constituent SR Policy sub-TLVs does not matter. The Constituent SR 161 Policy sub-TLV MAY contain a Weight sub-TLV. 163 Since a candidate path is either dynamic, explicit or composite, the 164 Constituent SR Policy sub-TLV and the Segment List sub-TLV SHOULD NOT 165 appear in the same BGP Tunnel Encapsulation Attribute. 167 The Constituent SR Policy sub-TLV has the following format: 169 0 1 2 3 170 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 1 171 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 172 | Type | Length | RESERVED | 173 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 174 | Color | 175 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 176 | sub-TLVs | 177 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 178 where: 180 o Type: to be assigned by IANA. 182 o Length: the total length of the value field not including Type and 183 Length fields. 185 o RESERVED: 2 octet of reserved bits. SHOULD be set to zero on 186 transmission and MUST be ignored on receipt. 188 o Color: 4-octet value identifying the constituent SR policy. 190 o sub-TLVs currently defined: 192 * An optional single Weight sub-TLV which is defined in section 193 2.4.4.1 in [I-D.ietf-idr-segment-routing-te-policy]. According 194 to [I-D.ietf-spring-segment-routing-policy], the fraction of 195 flows steered into each constituent SR Policy is equal to the 196 relative weight of each constituent SR Policy. 198 4. Operations 200 The document does not bring new operation beyond the description of 201 operations defined in [I-D.ietf-idr-segment-routing-te-policy]. The 202 existing operations defined in 203 [I-D.ietf-idr-segment-routing-te-policy] can apply to this document 204 directly. 206 Typically but not limit to, the SR policies carrying composite 207 candidate path information are configured by a controller. 209 After configuration, the SR policies carrying path composite 210 candidate path information will be advertised by BGP update messages. 211 The operation of advertisement is the same as defined in 212 [I-D.ietf-idr-segment-routing-te-policy], as well as the receiption. 214 5. Security Considerations 216 Procedures and protocol extensions defined in this document do not 217 affect the security considerations discussed in 218 [I-D.ietf-idr-segment-routing-te-policy]. 220 6. IANA Considerations 222 This document defines a new Sub-TLV in registries "SR Policy List 223 Sub-TLVs" [I-D.ietf-idr-segment-routing-te-policy]: 225 +-------+-------------------------------+---------------+ 226 | Value | Description | Reference | 227 +-------+-------------------------------+---------------+ 228 | TBA | Constituent SR Policy Sub-TLV | This document | 229 +-------+-------------------------------+---------------+ 231 7. Contributors 233 In addition to the authors listed on the front page, the following 234 co-authors have also contributed to this document: 236 Yuanxiang Qiu 237 Liping Yang 238 Yang Wang 240 8. References 242 8.1. Normative References 244 [I-D.ietf-idr-segment-routing-te-policy] 245 Previdi, S., Filsfils, C., Talaulikar, K., Mattes, P., 246 Rosen, E., Jain, D., and S. Lin, "Advertising Segment 247 Routing Policies in BGP", draft-ietf-idr-segment-routing- 248 te-policy-11 (work in progress), November 2020. 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 8.2. 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", draft- 269 ietf-spring-segment-routing-policy-09 (work in progress), 270 November 2020. 272 Authors' Addresses 274 Hao Li 275 H3C 277 Email: lihao@h3c.com 279 Mengxiao Chen 280 H3C 282 Email: chen.mengxiao@h3c.com 284 Changwang Lin 285 H3C 287 Email: linchangwang.04414@h3c.com