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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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-17) exists of draft-ietf-idr-segment-routing-te-policy-16 Summary: 0 errors (**), 0 flaws (~~), 1 warning (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 Network Working Group C. Lin 2 Internet Draft M. Chen 3 Intended status: Standards Track New H3C Technologies 4 Expires: September 29, 2022 March 29, 2022 6 BGP SR Policy Extensions for Segment List Identifier 7 draft-lin-idr-sr-policy-seglist-id-00 9 Abstract 11 Segment Routing is a source routing paradigm that explicitly 12 indicates the forwarding path for packets at the ingress node. An SR 13 Policy is a set of candidate paths, each consisting of one or more 14 segment lists. This document defines extensions to BGP SR Policy to 15 specify the identifier of segment list. 17 Status of this Memo 19 This Internet-Draft is submitted in full conformance with the 20 provisions of BCP 78 and BCP 79. 22 Internet-Drafts are working documents of the Internet Engineering 23 Task Force (IETF), its areas, and its working groups. Note that 24 other groups may also distribute working documents as Internet- 25 Drafts. 27 Internet-Drafts are draft documents valid for a maximum of six 28 months and may be updated, replaced, or obsoleted by other documents 29 at any time. It is inappropriate to use Internet-Drafts as 30 reference material or to cite them other than as "work in progress." 32 The list of current Internet-Drafts can be accessed at 33 http://www.ietf.org/ietf/1id-abstracts.txt 35 The list of Internet-Draft Shadow Directories can be accessed at 36 http://www.ietf.org/shadow.html 38 This Internet-Draft will expire on September 29, 2022. 40 Copyright Notice 42 Copyright (c) 2022 IETF Trust and the persons identified as the 43 document authors. All rights reserved. 45 This document is subject to BCP 78 and the IETF Trust's Legal 46 Provisions Relating to IETF Documents 47 (http://trustee.ietf.org/license-info) in effect on the date of 48 publication of this document. Please review these documents 49 carefully, as they describe your rights and restrictions with 50 respect to this document. Code Components extracted from this 51 document must include Simplified BSD License text as described in 52 Section 4.e of the Trust Legal Provisions and are provided without 53 warranty as described in the Simplified BSD License. 55 Table of Contents 57 1. Introduction ................................................ 2 58 1.1. Requirements Language .................................. 3 59 2. Segment List Identifier in SR Policy ........................ 3 60 2.1. Segment List ID Sub-TLV ................................ 4 61 2.2. Segment List Name Sub-TLV .............................. 5 62 3. Security Considerations ..................................... 5 63 4. IANA Considerations ......................................... 6 64 5. References .................................................. 6 65 5.1. Normative References ................................... 6 66 5.2. 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 However, there is no identifier for segment list in BGP SR Policy, 80 which may cause inconvenience for other mechanisms to designate 81 segment lists distributed by BGP. 83 For example, a network controller distributes SR policies to the 84 headend nodes, and the headend nodes collect traffic forwarding 85 statistics per segment list. When a headend node report each 86 statistic to the controller, it needs to specify the segment list 87 which the statistic belongs to. Due to the lack of identifier, the 88 headend node usually reports all SIDs in the associated segment list 89 along with the statistic, and the controller needs to distinguish 90 the segment list by comparing the SIDs one by one. The advertisement 91 of all SIDs in the segment list consumes a lot of octets, and the 92 comparison of SIDs can be complicated. 94 For another example, a network controller distributes SR policies 95 using BGP, and then it uses NETCONF to set some configurations of 96 the segment lists, which are not suitable to be carried in BGP. So 97 the controller needs to specify the segment list which the 98 configurations belong to. In this case, a simple identifier of 99 segment list can also be helpful. 101 This document defines extensions to BGP SR Policy to specify the 102 identifier of segment list. 104 1.1. Requirements Language 106 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 107 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 108 "OPTIONAL" in this document are to be interpreted as described in 109 BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all 110 capitals, as shown here. 112 2. Segment List Identifier in SR Policy 114 As defined in [I-D.ietf-idr-segment-routing-te-policy], the SR 115 policy encoding structure is as follows: 117 SR Policy SAFI NLRI: 118 Attributes: 119 Tunnel Encaps Attribute (23) 120 Tunnel Type: SR Policy 121 Binding SID 122 SRv6 Binding SID 123 Preference 124 Priority 125 Policy Name 126 Policy Candidate Path Name 127 Explicit NULL Label Policy (ENLP) 128 Segment List 129 Weight 130 Segment 131 Segment 132 ... 133 ... 135 SR policy with segment list identifier is expressed as below: 137 SR Policy SAFI NLRI: 138 Attributes: 139 Tunnel Encaps Attribute (23) 140 Tunnel Type: SR Policy 141 Binding SID 142 SRv6 Binding SID 143 Preference 144 Priority 145 Policy Name 146 Policy Candidate Path Name 147 Explicit NULL Label Policy (ENLP) 148 Segment List 149 Weight 150 Segment List Identifier 151 Segment 152 Segment 153 ... 154 ... 156 The segment list identifier can be advertised using the Segment List 157 ID sub-TLV or the Segment List Name sub-TLV, as defined in Section 158 2.1 and 2.2. 160 2.1. Segment List ID Sub-TLV 162 The Segment List ID sub-TLV specifies the identifier of the segment 163 list by a 4-octet number. 165 The Segment List ID sub-TLV is optional and it MUST NOT appear more 166 than once inside the Segment List sub-TLV. 168 The Segment List ID sub-TLV has the following format: 170 0 1 2 3 171 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 1 172 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 173 | Type | Length | Flags | RESERVED | 174 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 175 | Segment List ID | 176 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 178 where: 180 o Type: TBD. 182 o Length: 6. 184 o Flags: 1 octet of flags. None are defined at this stage. Flags 185 SHOULD be set to zero on transmission and MUST be ignored on 186 receipt. 188 o RESERVED: 1 octet of reserved bits. SHOULD be set to zero on 189 transmission and MUST be ignored on receipt. 191 o Segment List ID: 4 octet of ID for the segment list. 193 2.2. Segment List Name Sub-TLV 195 The Segment List Name sub-TLV specifies the identifier of the 196 segment list by a symbolic name. 198 The Segment List Name sub-TLV is optional and it MUST NOT appear 199 more than once inside the Segment List sub-TLV. 201 The Segment List Name sub-TLV has the following format: 203 0 1 2 3 204 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 1 205 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 206 | Type | Length | Flags | RESERVED | 207 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 208 // Segment List Name // 209 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 211 where: 213 o Type: TBD. 215 o Length: Variable. 217 o Flags: 1 octet of flags. None are defined at this stage. Flags 218 SHOULD be set to zero on transmission and MUST be ignored on 219 receipt. 221 o RESERVED: 1 octet of reserved bits. SHOULD be set to zero on 222 transmission and MUST be ignored on receipt. 224 o Segment List Name: Symbolic name for the segment list. It SHOULD 225 be a string of printable ASCII characters, without a NULL 226 terminator. 228 3. Security Considerations 230 TBD 232 4. IANA Considerations 234 Segment List ID sub-TLV and Segment List Name sub-TLV (TBD) 236 5. References 238 5.1. Normative References 240 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 241 Requirement Levels", BCP 14, RFC 2119, March 1997. 243 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 244 2119 Key Words", BCP 14, RFC 8174, May 2017 246 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., 247 Decraene, B., Litkowski, S., and R. Shakir, "Segment 248 Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, 249 July 2018, . 251 [I-D.ietf-idr-segment-routing-te-policy] Previdi, S., Filsfils, C., 252 Talaulikar, K., Mattes, P., Rosen, E., Jain, D., and S. 253 Lin, "Advertising Segment Routing Policies in BGP", Work 254 in Progress, Internet- Draft, draft-ietf-idr-segment- 255 routing-te-policy-16, 7 March 2022, 256 . 259 5.2. Informative References 261 [I-D.ietf-spring-segment-routing-policy] Filsfils, C., Talaulikar, 262 K., Voyer, D., Bogdanov, A., and P. Mattes, "Segment 263 Routing Policy Architecture", Work in Progress, Internet- 264 Draft, draft-ietf-spring-segment- routing-policy-22, 22 265 March 2022, . 268 Authors' Addresses 270 Changwang Lin 271 New H3C Technologies 273 Email: linchangwang.04414@h3c.com 275 Mengxiao Chen 276 New H3C Technologies 278 Email: chen.mengxiao@h3c.com