idnits 2.17.1 draft-nainar-mpls-spring-lsp-ping-sr-generic-sid-04.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 4 instances of too long lines in the document, the longest one being 7 characters in excess of 72. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (October 27, 2020) is 1271 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) No issues found here. Summary: 1 error (**), 0 flaws (~~), 1 warning (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Work group N. Nainar, Ed. 3 Internet-Draft C. Pignataro, Ed. 4 Intended status: Standards Track Z. Ali 5 Expires: April 30, 2021 C. Filsfils 6 Cisco 7 T. Saad 8 Juniper 9 October 27, 2020 11 Segment Routing Generic TLV for MPLS Label Switched Path (LSP) Ping/ 12 Traceroute 13 draft-nainar-mpls-spring-lsp-ping-sr-generic-sid-04 15 Abstract 17 RFC8402 introduces Segment Routing architecture that leverages source 18 routing and tunneling paradigms and can be directly applied to the 19 Multi Protocol Label Switching (MPLS) data plane. A node steers a 20 packet through a controlled set of instructions called segments, by 21 prepending the packet with Segment Routing header. SR architecture 22 defines different types of segments with different forwarding 23 semantics associated. SR can be applied to the MPLS directly and to 24 IPv6 dataplane using a new routing header. 26 RFC8287 defines the extensions to MPLS LSP Ping and Traceroute for 27 Segment Routing IGP-Prefix and IGP-Adjacency Segment Identifier 28 (SIDs) with an MPLS data plane. Various SIDs are proposed as part of 29 SR architecture with different associated instructions that raises a 30 need to come up with new Target FEC Stack Sub-TLV for each such SIDs. 32 This document defines a new Target FEC Stack Sub-TLV that is used to 33 validate the instruction associated with any SID. 35 Status of This Memo 37 This Internet-Draft is submitted in full conformance with the 38 provisions of BCP 78 and BCP 79. 40 Internet-Drafts are working documents of the Internet Engineering 41 Task Force (IETF). Note that other groups may also distribute 42 working documents as Internet-Drafts. The list of current Internet- 43 Drafts is at https://datatracker.ietf.org/drafts/current/. 45 Internet-Drafts are draft documents valid for a maximum of six months 46 and may be updated, replaced, or obsoleted by other documents at any 47 time. It is inappropriate to use Internet-Drafts as reference 48 material or to cite them other than as "work in progress." 49 This Internet-Draft will expire on April 30, 2021. 51 Copyright Notice 53 Copyright (c) 2020 IETF Trust and the persons identified as the 54 document authors. All rights reserved. 56 This document is subject to BCP 78 and the IETF Trust's Legal 57 Provisions Relating to IETF Documents 58 (https://trustee.ietf.org/license-info) in effect on the date of 59 publication of this document. Please review these documents 60 carefully, as they describe your rights and restrictions with respect 61 to this document. Code Components extracted from this document must 62 include Simplified BSD License text as described in Section 4.e of 63 the Trust Legal Provisions and are provided without warranty as 64 described in the Simplified BSD License. 66 Table of Contents 68 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 69 1.1. Challenges with Existing Mechanism . . . . . . . . . . . 3 70 2. Requirements notation . . . . . . . . . . . . . . . . . . . . 3 71 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 72 4. Target FEC Stack sub-TLV for Segment Routing SID . . . . . . 4 73 4.1. Segment Routing Generic Label . . . . . . . . . . . . . . 4 74 4.2. FEC for Path validation . . . . . . . . . . . . . . . . . 4 75 5. Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 5 76 5.1. SID to Interface Mapping . . . . . . . . . . . . . . . . 5 77 5.2. Initiator behavior . . . . . . . . . . . . . . . . . . . 6 78 5.2.1. SRGL in Target FEC Stack TLV . . . . . . . . . . . . 6 79 5.3. Responder behavior . . . . . . . . . . . . . . . . . . . 7 80 5.4. PHP flag behavior . . . . . . . . . . . . . . . . . . . . 7 81 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 82 6.1. New Target FEC Stack Sub-TLVs . . . . . . . . . . . . . . 8 83 6.2. Security Considerations . . . . . . . . . . . . . . . . . 8 84 7. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 8 85 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 8 86 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 87 9.1. Normative References . . . . . . . . . . . . . . . . . . 8 88 9.2. Informative References . . . . . . . . . . . . . . . . . 9 89 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 91 1. Introduction 93 [RFC8402] introduces and describes a Segment Routing architecture 94 that leverages the source routing and tunneling paradigms. A node 95 steers a packet through a controlled set of instructions called 96 segments, by prepending the packet with Segment Routing header. A 97 detailed definition of the Segment Routing architecture is available 98 in [RFC8402] 100 As described in [RFC8402] and [I-D.ietf-spring-segment-routing-mpls], 101 the Segment Routing architecture can be directly applied to an MPLS 102 data plane, the Segment identifier (Segment ID) will be of 20-bits 103 size and the Segment Routing header is the label stack. 105 1.1. Challenges with Existing Mechanism 107 [RFC8287] defines the mechanism to perform LSP Ping and Traceroute 108 for Segment Routing with MPLS data plane. [RFC8287] defines the 109 Target FEC Stack Sub-TLVs for IGP-Prefix Segment ID and IGP-Adjacency 110 Segment ID. 112 There are various other Segment IDs proposed by different documents 113 that are applicable for SR architecture. 114 [I-D.ietf-idr-bgp-prefix-sid] defines BGP Prefix Segment ID, 115 [I-D.ietf-idr-bgpls-segment-routing-epe] defines BGP Peering Segment 116 ID such as Peer Node SID, Peer Adj SID and Peer Set SID. 117 [I-D.sivabalan-pce-binding-label-sid] defines Path Binding Segment 118 ID. As SR evolves for different usecases, we may see more types of 119 SIDs defined in the future. This raises a need to propose new Target 120 FEC Stack Sub-TLV for each such Segment ID that may need specific or 121 network wide software upgrade to support such new Target FEC Stack 122 Sub-TLVs. 124 So instead of proposing different Target FEC Stack Sub-TLV for each 125 SID, this document attempt to propose a SR Generic Label Sub-TLV for 126 Target FEC Stack TLV with the procedure to validate the associated 127 instruction. 129 This document describes the new Target FEC Stack Sub-TLV that carries 130 the SID and the procedure to use LSP Ping and Traceroute using the 131 new sub-tlv to support path validation and fault isolation for any SR 132 Segment IDs. This document neither deprecates any existing Target 133 FEC Stack Sub-TLVs nor precludes defining new Sub-TLVs in the future. 135 2. Requirements notation 137 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 138 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 139 "OPTIONAL" in this document are to be interpreted as described in RFC 140 2119 [RFC2119] RFC 8174 [RFC8174] when and only when, they appear in 141 all capitals, as shown here. 143 3. Terminology 145 This document uses the terminologies defined in [RFC8402], [RFC8029], 146 readers are expected to be familiar with it. 148 4. Target FEC Stack sub-TLV for Segment Routing SID 150 Following the procedure defined in [RFC8029], below defined Target 151 FEC Stack Sub-TLV will be included for each labels in the stack. The 152 below Sub-TLV is defined for Target FEC Stack TLV (Type 1), the 153 Reverse-Path Target FEC Stack TLV (Type 16), and the Reply Path TLV 154 (Type 21). 156 sub-Type Value Field 157 -------- --------------- 158 TBD1 Segment Routing Generic Label (SRGL) 160 4.1. Segment Routing Generic Label 162 The format of the Sub-TLV is as specified below: 164 0 1 2 3 165 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 1 166 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 167 | SR SID | 168 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 170 SR SID 172 Carries 20 bits of Segment ID that is used for validating the 173 instruction. 175 4.2. FEC for Path validation 177 In SR architecture, any SID is associated with topology or service 178 instruction. While the topology instruction steers the packet over 179 best path or specific path, the service instruction instructs the 180 type of service to be applied on the packet. 182 R3-------R6 L1 183 / \ +-------+ 184 / \ | L2 | 185 R1----R2 R7------R8 186 \ / 187 \ / 188 R4-------R5 190 Figure 1: Segment Routing network 192 The Node Segment IDs for Rx for Algo 0 is 16000x. (Ex: For R1, it is 160001) 193 The Node Segment IDs for Rx for Algo 128 is 16128x. (Ex: For R1, it is 161281) 195 9178 --> Adjacency Segment ID from R7 to R8 over link L1. 196 9278 --> Adjacency Segment ID from R7 to R8 over link L2. 197 9378 --> Parallel Adjacency Segment ID from R7 to R8 over Link L1 or L2. 198 9187 --> Adjacency Segment ID from R8 to R7 over link L1. 199 9287 --> Adjacency Segment ID from R8 to R7 over link L2. 200 9387 --> Parallel Adjacency Segment ID from R8 to R7 over Link L1 or L2. 202 The instruction associated with any SID can be validated by verifying 203 if the segment is terminated on the correct node and optionally 204 received over the correct incoming interface. In Figure 1, inorder 205 to validate the SID 9178, R1 can use {(SID=9178)} as FEC in Target 206 FEC Stack Sub-TLV. 208 5. Procedures 210 This section describes the procedure to validate SR Generic Label 211 Sub-TLV. 213 5.1. SID to Interface Mapping 215 Any End point MAY maintain a SID to Interface mapping table that 216 maintains the below: 218 o All the local Prefix/Node SID with any SR enabled interface as 219 incoming interface. 221 o All the Adj-SIDs assigned by directly connected neighbor nodes 222 with the relevant interface incoming interface. 224 In Figure 1, R8 maintains 160008 and 161288 with Incoming interface 225 as any SR enabled interface. Similarly, R8 maintains 9178 with Link 226 L1 as incoming interface, 9278 with Link L2 as incoming interface and 227 9378 with Link L1 or L2 as incoming interface. 229 How this mapping is populated and maintained is a local 230 implementation matter. It can be populated based on the IGP database 231 or can be based on a query to Path Computation Element (PCE) 232 controller. The mapping can be persistent or on-demand triggered by 233 receiving LSP Ping Request. 235 5.2. Initiator behavior 237 This section defines the Target FEC Stack TLV construction mechanism 238 by an initiator when using SR Generic Label Sub-TLV. 240 Ping 242 Initiator MUST include FEC(s) corresponding to the destination 243 segment. 245 Initiator MAY include FECs corresponding to some or all of 246 segments imposed in the label stack by the initiator to 247 communicate the segments traversed. 249 Traceroute 251 Initiator MUST initially include FECs corresponding to all of 252 segments imposed in the label stack. 254 When a received echo reply contains FEC Stack Change TLV with 255 one or more of original segment(s) being popped, initiator MAY 256 remove corresponding FEC(s) from Target FEC Stack TLV in the 257 next (TTL+1) traceroute request as defined in section 4.6 of 258 [RFC8029]. 260 When a received echo reply does not contain FEC Stack Change 261 TLV, initiator MUST NOT attempt to remove FEC(s) from Target 262 FEC Stack TLV in the next (TTL+1) traceroute request. 264 5.2.1. SRGL in Target FEC Stack TLV 266 When the last segment ID in the label stack is IGP Prefix SID, Adj- 267 SID, Binding SID, BGP Prefix SID or BGP Peering SID, set the SR SID 268 field to the Segment ID value advertised by the LSP End Point. When 269 the SID is advertised as index, the Segment ID value MUST be derived 270 based on the index and the SRGB advertised by the LSP End Point. 272 How the above values are derived is a local implementation matter. 273 It can be manually defined using CLI knob while triggering the LSP 274 Ping Request or can use other mechanisms like querying the local 275 database. 277 5.3. Responder behavior 279 Step 4a defined in Section 7.4 of [RFC8287] is updated as below: 281 If the Label-stack-depth is 0 and Target FEC Stack Sub-TLV at FEC- 282 stack-depth is TBD1 (SRGL) { 284 * Set the Best-return-code to 10 when the responding node is not 285 the LSP End Point for SR SID. 287 * Set the Best-return-code to 35, if Interface-I does not match 288 the SID to Interface mapping for the received SR SID. 290 * set FEC-Status to 1, and return. 292 } 294 If the Label-stack-depth is greater than 0 and Target FEC Stack 295 Sub-TLV at FEC-stack-depth is TBD1 (SRGL), { 297 * If the Label at Label-stack-depth is Imp-null { 299 + Set the Best-return-code to 10 when the responding node is 300 not the LSP End Point for the SR SID. 302 + Set the Best-return-code to 35, if Interface-I does not 303 match the SID to Interface mapping for the received SR SID. 305 + set FEC-Status to 1, and return. 307 } 309 * Else: 311 + Set the Best-return-code to 10 when the index derived from 312 the label at Label-stack-depth is not advertised by LSP End 313 Point. 315 + set FEC-Status to 1, and return. 317 } 319 5.4. PHP flag behavior 321 Section 7.2 of [RFC8287] explains the behavior for FEC stack change 322 for Adjacency Segment ID. The same procedure is applicable for BGP 323 Peering SID as well. 325 6. IANA Considerations 327 6.1. New Target FEC Stack Sub-TLVs 329 IANA is requested to assign three new Sub-TLVs from "Sub-TLVs for TLV 330 Types 1, 16 and 21" sub-registry from the "Multi-Protocol Label 331 Switching (MPLS) Label Switched Paths (LSPs) Ping Parameters" 332 [IANA-MPLS-LSP-PING] registry. 334 Sub-Type Sub-TLV Name Reference 335 -------- ----------------- ------------ 336 TBD1 Segment Routing Generic Label Section 4.1 of this document 338 6.2. Security Considerations 340 This document defines additional MPLS LSP Ping Sub-TLVs and follows 341 the mechanisms defined in [RFC8029]. All the security considerations 342 defined in [RFC8029] will be applicable for this document, and in 343 addition, they do not impose any additional security challenges to be 344 considered. 346 7. Acknowledgement 348 TBD 350 8. Contributors 352 Danial Johari, Cisco Systems 354 9. References 356 9.1. Normative References 358 [I-D.ietf-idr-bgp-prefix-sid] 359 Previdi, S., Filsfils, C., Lindem, A., Sreekantiah, A., 360 and H. Gredler, "Segment Routing Prefix SID extensions for 361 BGP", draft-ietf-idr-bgp-prefix-sid-27 (work in progress), 362 June 2018. 364 [I-D.ietf-idr-bgpls-segment-routing-epe] 365 Previdi, S., Talaulikar, K., Filsfils, C., Patel, K., Ray, 366 S., and J. Dong, "BGP-LS extensions for Segment Routing 367 BGP Egress Peer Engineering", draft-ietf-idr-bgpls- 368 segment-routing-epe-19 (work in progress), May 2019. 370 [I-D.sivabalan-pce-binding-label-sid] 371 Sivabalan, S., Filsfils, C., Tantsura, J., Hardwick, J., 372 Previdi, S., and C. Li, "Carrying Binding Label/Segment-ID 373 in PCE-based Networks.", draft-sivabalan-pce-binding- 374 label-sid-07 (work in progress), July 2019. 376 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 377 Requirement Levels", BCP 14, RFC 2119, 378 DOI 10.17487/RFC2119, March 1997, 379 . 381 [RFC8029] Kompella, K., Swallow, G., Pignataro, C., Ed., Kumar, N., 382 Aldrin, S., and M. Chen, "Detecting Multiprotocol Label 383 Switched (MPLS) Data-Plane Failures", RFC 8029, 384 DOI 10.17487/RFC8029, March 2017, 385 . 387 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 388 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 389 May 2017, . 391 [RFC8287] Kumar, N., Ed., Pignataro, C., Ed., Swallow, G., Akiya, 392 N., Kini, S., and M. Chen, "Label Switched Path (LSP) 393 Ping/Traceroute for Segment Routing (SR) IGP-Prefix and 394 IGP-Adjacency Segment Identifiers (SIDs) with MPLS Data 395 Planes", RFC 8287, DOI 10.17487/RFC8287, December 2017, 396 . 398 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., 399 Decraene, B., Litkowski, S., and R. Shakir, "Segment 400 Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, 401 July 2018, . 403 9.2. Informative References 405 [I-D.ietf-spring-segment-routing-mpls] 406 Bashandy, A., Filsfils, C., Previdi, S., Decraene, B., 407 Litkowski, S., and R. Shakir, "Segment Routing with MPLS 408 data plane", draft-ietf-spring-segment-routing-mpls-22 409 (work in progress), May 2019. 411 [IANA-MPLS-LSP-PING] 412 IANA, "Multi-Protocol Label Switching (MPLS) Label 413 Switched Paths (LSPs) Ping Parameters", 414 . 417 Authors' Addresses 419 Nagendra Kumar Nainar (editor) 420 Cisco Systems, Inc. 421 7200-12 Kit Creek Road 422 Research Triangle Park, NC 27709-4987 423 US 425 Email: naikumar@cisco.com 427 Carlos Pignataro (editor) 428 Cisco Systems, Inc. 429 7200-11 Kit Creek Road 430 Research Triangle Park, NC 27709-4987 431 US 433 Email: cpignata@cisco.com 435 Zafar Ali 436 Cisco Systems, Inc. 438 Email: zali@cisco.com 440 Clarence Filsfils 441 Cisco Systems, Inc. 443 Email: cfilsfil@cisco.com 445 Tarek Saad 446 Juniper Networks 448 Email: tsaad@juniper.net