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Aldrin 7 Google Inc. 8 November 21, 2016 10 Definition of P2MP PW TLV for LSP-Ping Mechanisms 11 draft-jain-pals-p2mp-pw-lsp-ping-02 13 Abstract 15 LSP-Ping is a widely deployed Operation, Administration, and 16 Maintenance (OAM) mechanism in MPLS networks. This document 17 describes a mechanism to verify connectivity of Point-to-Multipoint 18 (P2MP) Pseudowires (PW) using LSP Ping. 20 Status of This Memo 22 This Internet-Draft is submitted in full conformance with the 23 provisions of BCP 78 and BCP 79. 25 Internet-Drafts are working documents of the Internet Engineering 26 Task Force (IETF). Note that other groups may also distribute 27 working documents as Internet-Drafts. The list of current Internet- 28 Drafts is at http://datatracker.ietf.org/drafts/current/. 30 Internet-Drafts are draft documents valid for a maximum of six months 31 and may be updated, replaced, or obsoleted by other documents at any 32 time. It is inappropriate to use Internet-Drafts as reference 33 material or to cite them other than as "work in progress." 35 This Internet-Draft will expire on May 25, 2017. 37 Copyright Notice 39 Copyright (c) 2016 IETF Trust and the persons identified as the 40 document authors. All rights reserved. 42 This document is subject to BCP 78 and the IETF Trust's Legal 43 Provisions Relating to IETF Documents 44 (http://trustee.ietf.org/license-info) in effect on the date of 45 publication of this document. Please review these documents 46 carefully, as they describe your rights and restrictions with respect 47 to this document. Code Components extracted from this document must 48 include Simplified BSD License text as described in Section 4.e of 49 the Trust Legal Provisions and are provided without warranty as 50 described in the Simplified BSD License. 52 Table of Contents 54 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 55 2. Specification of Requirements . . . . . . . . . . . . . . . . 3 56 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 57 4. Identifying a P2MP PW . . . . . . . . . . . . . . . . . . . . 3 58 4.1. P2MP Pseudowire Sub-TLV . . . . . . . . . . . . . . . . . 3 59 5. Encapsulation of OAM Ping Packets . . . . . . . . . . . . . . 4 60 6. Operations . . . . . . . . . . . . . . . . . . . . . . . . . 4 61 7. Controlling Echo Responses . . . . . . . . . . . . . . . . . 5 62 8. Security Considerations . . . . . . . . . . . . . . . . . . . 6 63 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 64 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6 65 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 66 11.1. Normative References . . . . . . . . . . . . . . . . . . 6 67 11.2. Informative References . . . . . . . . . . . . . . . . . 7 68 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 70 1. Introduction 72 A Point-to-Multipoint (P2MP) Pseudowire (PW) emulates the essential 73 attributes of a unidirectional P2MP Telecommunications service such 74 as P2MP ATM over PSN. Requirements for P2MP PW are described in 75 [RFC7338]. P2MP PWs are carried over P2MP MPLS LSP. The Procedures 76 for P2MP PW signaling using BGP are described in [RFC7117] and LDP 77 for single segment P2MP PWs are described in [I-D.ietf-pwe3-p2mp-pw]. 78 Many P2MP PWs can share the same P2MP MPLS LSP and this arrangement 79 is called Aggregate P-tree. The aggregate P2MP trees require an 80 upstream assigned label so that on the tail of the P2MP LSP, the 81 traffic can be associated with a VPN or a VPLS instance. When a P2MP 82 MPLS LSP carries only one VPN or VPLS service instance, the 83 arrangement is called Inclusive P-Tree. For Inclusive P-Trees, P2MP 84 MPLS LSP label itself can uniquely identify the VPN or VPLS service 85 being carried over P2MP MPLS LSP. The P2MP MPLS LSP can also be used 86 in Selective P-Tree arrangement for carrying multicast traffic. In a 87 Selective P-Tree arrangement, traffic to each multicast group in a 88 VPN or VPLS instance is carried by a separate unique P-tree. In 89 Aggregate Selective P-tree arrangement, traffic to a set of multicast 90 groups from different VPN or VPLS instances is carried over a same 91 shared P-tree. 93 The P2MP MPLS LSP are setup either using P2MP RSVP-TE [RFC4875] or 94 Multipoint LDP (mDLP) [RFC6388]. Mechanisms for fault detection and 95 isolation for data plane failures for P2MP MPLS LSPs are specified in 97 [RFC6425]. This document describes a mechanism to detect data plane 98 failures for P2MP PW carried over P2MP MPLS LSPs. 100 This document defines a new P2MP Pseudowire sub-TLV for Target FEC 101 Stack for P2MP PW. The P2MP Pseudowire sub-TLV is added in Target 102 FEC Stack TLV by the originator of the Echo Request to inform the 103 receiver at P2MP MPLS LSP tail, of the P2MP PW being tested. 105 Multi-segment Pseudowires support is out of scope of this document at 106 present and may be included in future. 108 2. Specification of Requirements 110 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 111 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 112 document are to be interpreted as described in [RFC2119]. 114 3. Terminology 116 ATM: Asynchronous Transfer Mode 118 LSR: Label Switching Router 120 MPLS-OAM: MPLS Operations, Administration and Maintenance 122 P2MP-PW: Point-to-Multipoint PseudoWire 124 PW: PseudoWire 126 TLV: Type Length Value 128 4. Identifying a P2MP PW 130 This document introduces a new LSP Ping Target FEC Stack sub-TLV, 131 P2MP Pseudowire sub-TLV, to identify the P2MP PW under test at the 132 P2MP LSP Tail/Bud node. 134 4.1. P2MP Pseudowire Sub-TLV 136 The P2MP Pseudowire sub-TLV has the format shown in Figure 1. This 137 TLV is included in the echo request sent over P2MP PW by the 138 originator of request. 140 The Attachment Group Identifier (AGI) in P2MP Pseudowire Sub-TLV as 141 described in Section 3.4.2 in [RFC4446], identifies the VPLS 142 instance. The Originating Router's IP address is the IPv4 or IPv6 143 address of the P2MP PW root. 145 0 1 2 3 146 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 1 147 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 148 | AGI Type | AGI Length | | 149 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 150 ~ AGI Value ~ 151 | | 152 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 153 | IP Addr Len | | 154 +-+-+-+-+-+-+-+ | 155 ~ Originating Routers IP Addr ~ 156 | | 157 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 159 Figure 1: P2MP Pseudowire sub-TLV format 161 For Inclusive and Selective P2MP MPLS P-trees, the echo request is 162 sent using the P2MP MPLS LSP label. 164 For Aggregate Inclusive and Aggregate Selective P-trees, the echo 165 request is sent using a label stack of [P2MP MPLS P-tree label, 166 upstream assigned P2MP PW label]. The P2MP MPLS P-tree label is the 167 outer label and upstream assigned P2MP PW label is inner label. 169 5. Encapsulation of OAM Ping Packets 171 The LSP Ping Echo request IPv4/UDP packets will be encapsulated with 172 the MPLS label stack as described in previous sections, followed by 173 the GAL Label [RFC6426]. The GAL label will be followed by the ACH 174 with the Pseudowire Associated Channel Type 16 bit value in the ACH 175 set to IPv4 indicating that the carried packet is an IPv4 packet. 177 6. Operations 179 In this section, we explain the operation of the LSP Ping over P2MP 180 PW. Figure 2 shows a P2MP PW PW1 setup from T-PE1 to remote PEs (T- 181 PE2, T-PE3 and T-PE4). The transport LSP associated with the P2MP 182 PW1 can be MLDP P2MP MPLS LSP or P2MP TE tunnel. 184 |<--------------P2MP PW---------------->| 185 Native | | Native 186 Service | |<--PSN1->| |<--PSN2->| | Service 187 (AC) V V V V V V (AC) 188 | +-----+ +------+ +------+ | 189 | | | | P1 |=========|T-PE2 |AC3 | +---+ 190 | | | | .......PW1.........>|-------->|CE3| 191 | |T-PE1|=========| . |=========| | | +---+ 192 | | .......PW1........ | +------+ | 193 | | . |=========| . | +------+ | 194 | | . | | . |=========|T-PE3 |AC4 | +---+ 195 +---+ |AC1 | . | | .......PW1.........>|-------->|CE4| 196 |CE1|------->|... | | |=========| | | +---+ 197 +---+ | | . | +------+ +------+ | 198 | | . | +------+ +------+ | 199 | | . |=========| P2 |=========|T-PE4 |AC5 | +---+ 200 | | .......PW1..............PW1.........>|-------->|CE5| 201 | | |=========| |=========| | | +---+ 202 | +-----+ +------+ +------+ | 204 Figure 2: P2MP PW 206 When an operator wants to perform a connectivity check for the P2MP 207 PW1, the operator initiate a LSP-Ping request with the Target FEC 208 Stack TLV containing P2MP Pseudowire sub-TLV in the echo request 209 packet. For an Inclusive P2MP P-tree arrangement, the echo request 210 packet is sent over the P2MP MPLS LSP with {P2MP P-tree label, GAL} 211 MPLS label stack and IP ACH Channel header. For an Aggregate 212 Inclusive P-tree arrangement, the echo request packet is sent over 213 the P2MP MPLS LSP with {P2MP P-tree label, P2MP PW upstream assigned 214 label, GAL} MPLS label stack and IP ACH Channel header. The 215 intermediate P router will do swap and replication based on the MPLS 216 LSP label. Once the echo request packet reaches remote terminating 217 PEs, T-PE1s will use the GAL label and the IP ACH Channel header to 218 determine that the packet is IPv4 OAM Packet. The T-PEs will process 219 the packet and perform checks for the P2MP Pseudowire sub-TLV present 220 in the Target FEC Stack TLV as described in Section 4.4 in [RFC4379] 221 and respond according to [RFC4379] processing rules. 223 7. Controlling Echo Responses 225 The procedures described in [RFC6425] for preventing congestion of 226 Echo Responses (Echo Jitter TLV) and limiting the echo reply to a 227 single egress node (Node Address P2MP Responder Identifier TLV) can 228 be applied to P2MP PW LSP Ping. 230 8. Security Considerations 232 The proposal introduced in this document does not introduce any new 233 security considerations beyond that already apply to [RFC6425]. 235 9. IANA Considerations 237 This document defines a new sub-TLV type to be included in Target FEC 238 Stack TLV (TLV Type 1) [RFC4379] in LSP Ping. 240 IANA is requested to assign a sub-TLV type value to the following 241 sub-TLV from the "Multiprotocol Label Switching (MPLS) Label Switched 242 Paths (LSPs) Parameters - TLVs" registry, "TLVs and sub- TLVs" sub- 243 registry: 245 o P2MP Pseudowire sub-TLV 247 10. Acknowledgments 249 The authors would like to thank Shaleen Saxena, Michael Wildt, 250 Tomofumi Hayashi, Danny Prairie for their valuable input and 251 comments. 253 11. References 255 11.1. Normative References 257 [I-D.ietf-pwe3-p2mp-pw] 258 Sivabalan, S., Boutros, S., and L. Martini, "Signaling 259 Root-Initiated Point-to-Multipoint Pseudowire using LDP", 260 draft-ietf-pwe3-p2mp-pw-04 (work in progress), March 2012. 262 [RFC4379] Kompella, K. and G. Swallow, "Detecting Multi-Protocol 263 Label Switched (MPLS) Data Plane Failures", RFC 4379, 264 DOI 10.17487/RFC4379, February 2006, 265 . 267 [RFC4446] Martini, L., "IANA Allocations for Pseudowire Edge to Edge 268 Emulation (PWE3)", BCP 116, RFC 4446, 269 DOI 10.17487/RFC4446, April 2006, 270 . 272 [RFC6425] Saxena, S., Ed., Swallow, G., Ali, Z., Farrel, A., 273 Yasukawa, S., and T. Nadeau, "Detecting Data-Plane 274 Failures in Point-to-Multipoint MPLS - Extensions to LSP 275 Ping", RFC 6425, DOI 10.17487/RFC6425, November 2011, 276 . 278 [RFC6426] Gray, E., Bahadur, N., Boutros, S., and R. Aggarwal, "MPLS 279 On-Demand Connectivity Verification and Route Tracing", 280 RFC 6426, DOI 10.17487/RFC6426, November 2011, 281 . 283 [RFC7117] Aggarwal, R., Ed., Kamite, Y., Fang, L., Rekhter, Y., and 284 C. Kodeboniya, "Multicast in Virtual Private LAN Service 285 (VPLS)", RFC 7117, DOI 10.17487/RFC7117, February 2014, 286 . 288 11.2. Informative References 290 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 291 Requirement Levels", BCP 14, RFC 2119, 292 DOI 10.17487/RFC2119, March 1997, 293 . 295 [RFC4875] Aggarwal, R., Ed., Papadimitriou, D., Ed., and S. 296 Yasukawa, Ed., "Extensions to Resource Reservation 297 Protocol - Traffic Engineering (RSVP-TE) for Point-to- 298 Multipoint TE Label Switched Paths (LSPs)", RFC 4875, 299 DOI 10.17487/RFC4875, May 2007, 300 . 302 [RFC5085] Nadeau, T., Ed. and C. Pignataro, Ed., "Pseudowire Virtual 303 Circuit Connectivity Verification (VCCV): A Control 304 Channel for Pseudowires", RFC 5085, DOI 10.17487/RFC5085, 305 December 2007, . 307 [RFC6388] Wijnands, IJ., Ed., Minei, I., Ed., Kompella, K., and B. 308 Thomas, "Label Distribution Protocol Extensions for Point- 309 to-Multipoint and Multipoint-to-Multipoint Label Switched 310 Paths", RFC 6388, DOI 10.17487/RFC6388, November 2011, 311 . 313 [RFC7338] Jounay, F., Ed., Kamite, Y., Ed., Heron, G., and M. Bocci, 314 "Requirements and Framework for Point-to-Multipoint 315 Pseudowires over MPLS Packet Switched Networks", RFC 7338, 316 DOI 10.17487/RFC7338, September 2014, 317 . 319 Authors' Addresses 320 Parag Jain 321 Cisco Systems, Inc. 322 2000 Innovation Drive 323 Kanata, ON K2K-3E8 324 Canada 326 Email: paragj@cisco.com 328 Sami Boutros 329 VMWare, Inc. 330 USA 332 Email: sboutros@vmware.com 334 Sam Aldrin 335 Google Inc. 336 USA 338 Email: aldrin.ietf@gmail.com