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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) No issues found here. Summary: 0 errors (**), 0 flaws (~~), 1 warning (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 PCE Working Group A. Tokar 3 Internet-Draft S. Sivabalan 4 Intended status: Standards Track Cisco Systems, Inc. 5 Expires: January 1, 2020 M. Negi 6 Huawei Technologies 7 June 30, 2019 9 Carrying SID Algorithm information in PCE-based Networks. 10 draft-tokar-pce-sid-algo-00 12 Abstract 14 The Algorithm associated with a prefix Segment-ID (SID) defines the 15 path computation Algorithm used by Interior Gateway Protocols (IGPs). 16 This information is available to controllers such as the Path 17 Computation Element (PCE) via topology learning. This document 18 proposes an approach for informing headend routers regarding the 19 Algorithm associated with each prefix SID used in PCE-computed paths. 21 Requirements Language 23 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 24 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 25 document are to be interpreted as described in [RFC2119]. 27 Status of This Memo 29 This Internet-Draft is submitted in full conformance with the 30 provisions of BCP 78 and BCP 79. 32 Internet-Drafts are working documents of the Internet Engineering 33 Task Force (IETF). Note that other groups may also distribute 34 working documents as Internet-Drafts. The list of current Internet- 35 Drafts is at https://datatracker.ietf.org/drafts/current/. 37 Internet-Drafts are draft documents valid for a maximum of six months 38 and may be updated, replaced, or obsoleted by other documents at any 39 time. It is inappropriate to use Internet-Drafts as reference 40 material or to cite them other than as "work in progress." 42 This Internet-Draft will expire on January 1, 2020. 44 Copyright Notice 46 Copyright (c) 2019 IETF Trust and the persons identified as the 47 document authors. All rights reserved. 49 This document is subject to BCP 78 and the IETF Trust's Legal 50 Provisions Relating to IETF Documents 51 (https://trustee.ietf.org/license-info) in effect on the date of 52 publication of this document. Please review these documents 53 carefully, as they describe your rights and restrictions with respect 54 to this document. Code Components extracted from this document must 55 include Simplified BSD License text as described in Section 4.e of 56 the Trust Legal Provisions and are provided without warranty as 57 described in the Simplified BSD License. 59 Table of Contents 61 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 62 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 63 3. SR ERO NAI Extensions . . . . . . . . . . . . . . . . . . . . 3 64 4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 4 65 5. Security Considerations . . . . . . . . . . . . . . . . . . . 4 66 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 67 6.1. PCEP SR-ERO NAI Types . . . . . . . . . . . . . . . . . . 4 68 7. Normative References . . . . . . . . . . . . . . . . . . . . 4 69 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 71 1. Introduction 73 A PCE can compute SR-TE paths using prefix SIDs with different 74 Algorithms depending on the use-case, constraints, etc. While this 75 information is available on the PCE, there is no method of conveying 76 this information to the headend router. 78 Similarly, the headend can also compute SR-TE paths using different 79 Algorithms, and this information also needs to be conveyed to the PCE 80 for collection or troubleshooting purposes. In addition, in the case 81 of multiple (redundant) PCEs, when the headend receives a path from 82 the primary PCE, it needs to be able to report the complete path 83 information - including the Algorithm - to the backup PCE so that in 84 HA scenarios, the backup PCE can verify the prefix SIDs 85 appropriately. 87 Refer to [I-D.ietf-ospf-segment-routing-extensions] and 88 [I-D.ietf-isis-segment-routing-extensions] for details about the 89 prefix SID Algorithm. 91 This document introduces two new NAI types for the SR-ERO subobject, 92 which is defined in [I-D.ietf-pce-segment-routing]. 94 2. Terminology 96 The following terminologies are used in this document: 98 ERO: Explicit Route Object 100 IGP: Interior Gateway Protocol 102 NAI: Node or Adjacency Identifier. 104 PCE: Path Computation Element 106 PCEP: Path Computation Element Protocol. 108 SID: Segment Identifier. 110 SR: Segment Routing. 112 SR-TE: Segment Routing Traffic Engineering. 114 3. SR ERO NAI Extensions 116 The SR-ERO subobject encoding is extended with additional NAI types. 118 The following new NAI types (NT) are defined: 120 o NT=TBD1: The NAI is an IPv4 node ID with Algorithm. 122 o NT=TBD1: The NAI is an IPv6 node ID with Algorithm. 124 This document defines the following NAIs: 126 'IPv4 Node ID with Algorithm' is specified as an IPv4 address and 127 Algorithm identifier. In this case, the NT value is TBD1 and the 128 NAI field length is 8 octets. 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 | Node IPv4 address | 134 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 135 | Reserved | Algorithm | 136 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 138 Figure 1: NAI for IPv4 Node SID with Algorithm 140 'IPv6 Node ID with Algorithm' is specified as an IPv6 address and 141 Algorithm identifier. In this case, the NT value is TBD2 and the 142 NAI field length is 20 octets. 144 0 1 2 3 145 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 1 146 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 147 // Node IPv6 address (16 octets) // 148 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 149 | Reserved | Algorithm | 150 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 152 Figure 2: NAI for IPv6 Node SID with Algorithm 154 4. Operation 156 IPv4 prefix SIDs used by SR-TE paths with an associated Algorithm 157 SHOULD be encoded with 'IPv4 Node ID with Algorithm' NAI. 159 IPv6 prefix SIDs used by SR-TE paths with an associated Algorithm 160 SHOULD be encoded with 'IPv6 Node ID with Algorithm' NAI. 162 5. Security Considerations 164 No additional security measure is required. 166 6. IANA Considerations 168 6.1. PCEP SR-ERO NAI Types 170 IANA is requested to allocate new SR-ERO NAI types for the new NAI 171 types specified in this document. 173 Value Description Reference 175 TBD1 IPv4 Node ID with This document 176 Algorithm 177 TBD2 IPv6 Node ID with This document 178 Algorithm 180 7. Normative References 182 [I-D.ietf-isis-segment-routing-extensions] 183 Previdi, S., Ginsberg, L., Filsfils, C., Bashandy, A., 184 Gredler, H., and B. Decraene, "IS-IS Extensions for 185 Segment Routing", draft-ietf-isis-segment-routing- 186 extensions-25 (work in progress), May 2019. 188 [I-D.ietf-ospf-segment-routing-extensions] 189 Psenak, P., Previdi, S., Filsfils, C., Gredler, H., 190 Shakir, R., Henderickx, W., and J. Tantsura, "OSPF 191 Extensions for Segment Routing", draft-ietf-ospf-segment- 192 routing-extensions-27 (work in progress), December 2018. 194 [I-D.ietf-pce-segment-routing] 195 Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W., 196 and J. Hardwick, "PCEP Extensions for Segment Routing", 197 draft-ietf-pce-segment-routing-16 (work in progress), 198 March 2019. 200 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 201 Requirement Levels", BCP 14, RFC 2119, 202 DOI 10.17487/RFC2119, March 1997, 203 . 205 Authors' Addresses 207 Alex Tokar 208 Cisco Systems, Inc. 209 Eurovea Central 3. 210 Pribinova 10 211 Bratislava 811 09 212 Slovakia 214 Email: atokar@cisco.com 216 Siva Sivabalan 217 Cisco Systems, Inc. 218 2000 Innovation Drive 219 Kanata, Ontario K2K 3E8 220 Canada 222 Email: msiva@cisco.com 224 Mahendra Singh Negi 225 Huawei Technologies 226 Divyashree Techno Park, Whitefield 227 Bangalore, Karnataka 560066 228 India 230 Email: mahendrasingh@huawei.com