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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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-03) exists of draft-ietf-pals-redundancy-spe-02 Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group A. Malis, Ed. 3 Internet-Draft L. Andersson 4 Updates: 6870 (if approved) Huawei Technologies Co., Ltd 5 Intended status: Standards Track H. van Helvoort 6 Expires: April 24, 2016 Hai Gaoming BV 7 J. Shin 8 SK Telecom 9 L. Wang 10 China Mobile 11 A. D'Alessandro 12 Telecom Italia 13 October 22, 2015 15 S-PE Protection for MPLS and MPLS-TP Static Multi-Segment Pseudowires 16 draft-ietf-pals-ms-pw-protection-04.txt 18 Abstract 20 In MPLS and MPLS Transport Profile (MPLS-TP) environments, statically 21 provisioned Single-Segment Pseudowires (SS-PWs) are protected against 22 tunnel failure via MPLS-level and MPLS-TP-level tunnel protection. 23 With statically provisioned Multi-Segment Pseudowires (MS-PWs), each 24 segment of the MS-PW is likewise protected from tunnel failures via 25 MPLS-level and MPLS-TP-level tunnel protection. However, static MS- 26 PWs are not protected end-to-end against failure of one of the 27 Switching Provider Edge Routers (S-PEs) along the path of the MS-PW. 28 This document describes how to achieve this protection via redundant 29 MS-PWs by updating the existing procedures in RFC 6870. It also 30 contains an optional approach based on MPLS-TP Linear Protection. 32 Status of This Memo 34 This Internet-Draft is submitted in full conformance with the 35 provisions of BCP 78 and BCP 79. 37 Internet-Drafts are working documents of the Internet Engineering 38 Task Force (IETF). Note that other groups may also distribute 39 working documents as Internet-Drafts. The list of current Internet- 40 Drafts is at http://datatracker.ietf.org/drafts/current/. 42 Internet-Drafts are draft documents valid for a maximum of six months 43 and may be updated, replaced, or obsoleted by other documents at any 44 time. It is inappropriate to use Internet-Drafts as reference 45 material or to cite them other than as "work in progress." 47 This Internet-Draft will expire on April 24, 2016. 49 Copyright Notice 51 Copyright (c) 2015 IETF Trust and the persons identified as the 52 document authors. All rights reserved. 54 This document is subject to BCP 78 and the IETF Trust's Legal 55 Provisions Relating to IETF Documents 56 (http://trustee.ietf.org/license-info) in effect on the date of 57 publication of this document. Please review these documents 58 carefully, as they describe your rights and restrictions with respect 59 to this document. Code Components extracted from this document must 60 include Simplified BSD License text as described in Section 4.e of 61 the Trust Legal Provisions and are provided without warranty as 62 described in the Simplified BSD License. 64 Table of Contents 66 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 67 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 68 2. Extension to RFC 6870 to Protect Statically Provisioned SS- 69 PWs and MS-PWs . . . . . . . . . . . . . . . . . . . . . . . 3 70 3. Operational Considerations . . . . . . . . . . . . . . . . . 5 71 4. Security Considerations . . . . . . . . . . . . . . . . . . . 5 72 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 73 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 74 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 75 7.1. Normative References . . . . . . . . . . . . . . . . . . 6 76 7.2. Informative References . . . . . . . . . . . . . . . . . 6 77 Appendix A. Optional Linear Protection Approach . . . . . . . . 7 78 A.1. Introduction . . . . . . . . . . . . . . . . . . . . . . 7 79 A.2. Encapsulation of the PSC Protocol for Pseudowires . . . . 8 80 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 82 1. Introduction 84 In MPLS and MPLS Transport Profile (MPLS-TP) Packet Switched Networks 85 (PSNs), pseudowires (PWs) are transported by MPLS(-TP) Label Switched 86 Paths (LSPs), also known as tunnels. 88 As described in RFC 5659 [RFC5659], Multi-Segment Pseudowires (MS- 89 PWs) consist of Terminating Provider Edge Routers PEs (T-PEs), one or 90 more Switching Provider Edge Routers (S-PEs), and a sequence of 91 tunneled PW segments that connects one of the T-PEs with its 92 "adjacent" S-PE, connects this S-PE with the next S-PE in the 93 sequence and so on until the last S-PE is connected by the last PW 94 segment to the remaining T-PE. In MPLS and MPLS-TP environments, 95 statically provisioned Single-Segment Pseudowires (SS-PWs) are 96 protected against tunnel failure via MPLS-level and MPLS-TP-level 97 tunnel protection. With statically provisioned Multi-Segment 98 Pseudowires (MS-PWs), each PW segment of the MS-PW is likewise 99 protected from tunnel failure via MPLS-level and MPLS-TP-level tunnel 100 protection. However, tunnel protection does not protect static MS- 101 PWs from failures of S-PEs along the path of the MS-PW. 103 RFC 6718 [RFC6718] provides a general framework for PW protection, 104 and RFC 6870 [RFC6870], which is based upon that framework, describes 105 protection procedures for MS-PWs that are dynamically signaled using 106 LDP. This document describes how to achieve protection against S-PE 107 failure in a static MS-PW by extending RFC 6870 to be applicable for 108 statically provisioned MS-PWs pseudowires (PWs) as well. 110 This document also contains an OPTIONAL alternative approach based on 111 MPLS-TP Linear Protection. This approach, described in Appendix A, 112 MUST be identically provisioned in the PE endpoints for the protected 113 MS-PW in order to be used. See Appendix A for further details on 114 this alternative approach. 116 This document differs from [I-D.ietf-pals-redundancy-spe] in that 117 this draft provides end-to-end resiliency for static MS-PWs, while 118 [I-D.ietf-pals-redundancy-spe] provides resiliency at intermediate 119 S-PEs, rather than end-to-end resiliency, and for both dynamically 120 signaled and static MS-PWs. 122 Layer 2 Tunneling Protocol Version 3 (L2TPv3)-based PWs are outside 123 the scope of this document. 125 1.1. Requirements Language 127 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 128 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 129 document are to be interpreted as described in RFC 2119 [RFC2119]. 131 2. Extension to RFC 6870 to Protect Statically Provisioned SS-PWs and 132 MS-PWs 134 Section 3.2.3 of RFC 6718 and Section A.5 of RFC 6870 document how to 135 use redundant MS-PWs to protect an MS-PW against S-PE failure in the 136 case of a singly-homed CE, using the following network model from RFC 137 6718: 139 Native |<----------- Pseudowires ----------->| Native 140 Service | | Service 141 (AC) | |<-PSN1-->| |<-PSN2-->| | (AC) 142 | V V V V V V | 143 | +-----+ +-----+ +-----+ | 144 +----+ | |T-PE1|=========|S-PE1|=========|T-PE2| | +----+ 145 | |-------|......PW1-Seg1.......|.PW1-Seg2......|-------| | 146 | CE1| | |=========| |=========| | | CE2| 147 | | +-----+ +-----+ +-----+ | | 148 +----+ |.||.| |.||.| +----+ 149 |.||.| +-----+ |.||.| 150 |.||.|=========| |========== .||.| 151 |.||...PW2-Seg1......|.PW2-Seg2...||.| 152 |.| ===========|S-PE2|============ |.| 153 |.| +-----+ |.| 154 |.|============+-----+============= .| 155 |.....PW3-Seg1.| | PW3-Seg2......| 156 ==============|S-PE3|=============== 157 | | 158 +-----+ 160 Figure 1: Single-Homed CE with Redundant MS-PWs 162 In this figure, Customer Edge Router 1 (CE1) is connected to T-PE1 163 and CE2 is connected to T-PE2 via Attachment Circuits (ACs). There 164 are three MS-PWs. PW1 is switched at S-PE1, PW2 is switched at 165 S-PE2, and PW3 is switched at S-PE3. This scenario provides N:1 166 protection against S-PE failure for the subset of the path of the 167 emulated service from T-PE1 to T-PE2. 169 The procedures in RFCs 6718 and 6870 rely on LDP-based PW status 170 signaling to signal the state of the primary MS-PW that is being 171 protected, and the precedence in which redundant MS-PW(s) should be 172 used to protect the primary MS-PW should it fail. These procedures 173 make use of information carried by the PW Status TLV, which, for 174 dynamically signaled PWs, is carried by the LDP protocol. 176 However, statically provisioned PWs (SS-PWs or MS-PWs) do not use the 177 LDP protocol for PW set and signaling; rather they are provisioned by 178 network management systems or other means at each T-PE and S-PE along 179 their path. They also do not use the LDP protocol for status 180 signaling. Rather, they use procedures defined in RFC 6478 [RFC6478] 181 for status signaling via the PW OAM message using the PW Associated 182 Channel Header (ACH). The PW Status TLV carried via this status 183 signaling is itself identical to the PW Status TLV carried via LDP- 184 based status signaling, including the identical PW Status Codes. 186 Sections 6 and 7 of RFC 6870 describe the management of a primary PW 187 and its secondary PW(s) to provide resiliency to the failure of the 188 primary PW. They use status codes transmitted between endpoint T-PEs 189 using the PW Status TLV transmitted by LDP. For this management to 190 apply to statically provisioned PWs, the PW status signaling defined 191 in RFC 6478 MUST be used for the primary and secondary PWs. In that 192 case, the endpoint T-PEs can then use the PW status signaling 193 provided by RFC 6478 in place of LDP-based status signaling, so that 194 the status-signaling-based procedures in RFC 6870 operate identically 195 as when used with LDP-based status signaling. Note that the optional 196 S-PE Bypass Mode defined in Section 5.5 of RFC 6478 cannot be used, 197 as it requires LDP signaling. 199 3. Operational Considerations 201 Because LDP is not used between the T-PEs for statically provisioned 202 MS-PWs, the negotiation procedures described in RFC 6870 cannot be 203 used. Thus, operational care must be taken so that the endpoint 204 T-PEs are identically provisioned regarding the use of this document, 205 specifically whether or not MS-PW redundancy is being used, and for 206 each protected MS-PW, the identity of the primary MS-PW and the 207 precedence of the secondary MS-PWs. 209 4. Security Considerations 211 The security considerations defined for RFC 6478 apply to this 212 document as well. As the security considerations in RFCs 6718 and 213 6870 are related to their use of LDP, they are not required for this 214 document. 216 If the alternative approach in Appendix A is used, then the security 217 considerations defined for RFCs 6378, 7271, and 7324 also apply. 219 5. IANA Considerations 221 There are no requests for IANA actions in this document. 223 Note to the RFC Editor - this section can be removed before 224 publication. 226 6. Acknowledgements 228 The authors would like to thank Matthew Bocci, Yaakov Stein, David 229 Sinicrope, Sasha Vainshtein, and Italo Busi for their comments on 230 this document. 232 Figure 1 and the explanatory paragraph following the figure were 233 taken from RFC 6718. Figure 2 was adapted from RFC 6378. 235 7. References 237 7.1. Normative References 239 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 240 Requirement Levels", BCP 14, RFC 2119, 241 DOI 10.17487/RFC2119, March 1997, 242 . 244 [RFC6378] Weingarten, Y., Ed., Bryant, S., Osborne, E., Sprecher, 245 N., and A. Fulignoli, Ed., "MPLS Transport Profile (MPLS- 246 TP) Linear Protection", RFC 6378, DOI 10.17487/RFC6378, 247 October 2011, . 249 [RFC6478] Martini, L., Swallow, G., Heron, G., and M. Bocci, 250 "Pseudowire Status for Static Pseudowires", RFC 6478, 251 DOI 10.17487/RFC6478, May 2012, 252 . 254 [RFC6870] Muley, P., Ed. and M. Aissaoui, Ed., "Pseudowire 255 Preferential Forwarding Status Bit", RFC 6870, 256 DOI 10.17487/RFC6870, February 2013, 257 . 259 [RFC7271] Ryoo, J., Ed., Gray, E., Ed., van Helvoort, H., 260 D'Alessandro, A., Cheung, T., and E. Osborne, "MPLS 261 Transport Profile (MPLS-TP) Linear Protection to Match the 262 Operational Expectations of Synchronous Digital Hierarchy, 263 Optical Transport Network, and Ethernet Transport Network 264 Operators", RFC 7271, DOI 10.17487/RFC7271, June 2014, 265 . 267 [RFC7324] Osborne, E., "Updates to MPLS Transport Profile Linear 268 Protection", RFC 7324, DOI 10.17487/RFC7324, July 2014, 269 . 271 7.2. Informative References 273 [I-D.ietf-pals-redundancy-spe] 274 Dong, J. and H. Wang, "Pseudowire Redundancy on S-PE", 275 draft-ietf-pals-redundancy-spe-02 (work in progress), 276 August 2015. 278 [RFC5659] Bocci, M. and S. Bryant, "An Architecture for Multi- 279 Segment Pseudowire Emulation Edge-to-Edge", RFC 5659, 280 DOI 10.17487/RFC5659, October 2009, 281 . 283 [RFC6718] Muley, P., Aissaoui, M., and M. Bocci, "Pseudowire 284 Redundancy", RFC 6718, DOI 10.17487/RFC6718, August 2012, 285 . 287 Appendix A. Optional Linear Protection Approach 289 A.1. Introduction 291 In "MPLS Transport Profile (MPLS-TP) Linear Protection" [RFC6378], as 292 well as in the later updates of this RFC in "MPLS Transport Profile 293 (MPLS-TP) Linear Protection to Match the Operational Expectations of 294 Synchronous Digital Hierarchy, Optical Transport Network, and 295 Ethernet Transport Network Operators" [RFC7271] and in "Updates to 296 MPLS Transport Profile Linear Protection" [RFC7324], the Protection 297 State Coordination (PSC) protocol was defined for MPLS LSPs only. 299 This Appendix extends these RFCs to be applicable for PWs (SS-PW and 300 MS-PW) as well. This is useful especially in the case of end-to-end 301 static provisioned MS-PWs running over MPLS-TP where tunnel 302 protection alone cannot be relied upon for end-to-end protection of 303 PWs against S-PE failure. It also enables a uniform operational 304 approach for protection at LSP and PW layers and an easier management 305 integration for networks that already use RFCs 6378, 7271, and 7324. 307 The protection architectures are those defined in [RFC6378]. For the 308 purposes of this Appendix, we define the protection domain of a 309 point-to-point PW as consisting of two terminating PEs (T-PEs) and 310 the transport paths that connect them (see Figure 2). 312 +-----+ //=======================\\ +-----+ 313 |T-PE1|// Working Path \\|T-PE2| 314 | /| |\ | 315 | ?< | | >? | 316 | \|\\ Protection Path //|/ | 317 +-----+ \\=======================// +-----+ 319 |<-------Protection Domain------->| 321 Figure 2: Protection Domain 323 This Appendix is an OPTIONAL alternative approach to the one in 324 Section 2. For interoperability, all implementations MUST include 325 the approach in Section 2 even if this alternative approach is used. 326 The operational considerations in Section 3 continue to apply when 327 this approach is used, and operational care must be taken so that the 328 endpoint T-PEs are identically provisioned regarding the use of this 329 document. 331 A.2. Encapsulation of the PSC Protocol for Pseudowires 333 The PSC protocol can be used to protect against defects on any LSP 334 (segment, link, or path). In the case of MS-PW, the PSC protocol can 335 also protect failed intermediate nodes (S-PE). Linear protection 336 protects an LSP or PW end-to-end and if a failure is detected, 337 switches traffic over to another (redundant) set of resources. 339 Obviously, the protected entity does not need to be of the same type 340 as the protecting entity. For example, it is possible to protect a 341 link by a path. Likewise it is possible to protect an SS-PW with a 342 MS-PW and vice versa. 344 From a PSC protocol point of view it is possible to view a SS-PW as a 345 single hop LSP, and a MS-PW as a multiple hop LSP. Thus, this 346 provides end-to-end protection for the SS-PW or MS-PW. The Generic 347 Associated Channel (G-Ach) carrying the PSC protocol information is 348 placed in the label stack directly beneath the PW identifier. The 349 PSC protocol will then work as specified in RFCs 6378, 7271, and 350 7324. 352 Authors' Addresses 354 Andrew G. Malis (editor) 355 Huawei Technologies Co., Ltd 357 Email: agmalis@gmail.com 359 Loa Andersson 360 Huawei Technologies Co., Ltd 362 Email: loa@mail01.huawei.com 364 Huub van Helvoort 365 Hai Gaoming BV 367 Email: huubatwork@gmail.com 369 Jongyoon Shin 370 SK Telecom 372 Email: jongyoon.shin@sk.com 373 Lei Wang 374 China Mobile 376 Email: wangleiyj@chinamobile.com 378 Alessandro D'Alessandro 379 Telecom Italia 381 Email: alessandro.dalessandro@telecomitalia.it