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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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-15) exists of draft-mirsky-mpls-p2mp-bfd-12 Summary: 0 errors (**), 0 flaws (~~), 3 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group T. Morin, Ed. 3 Internet-Draft Orange 4 Intended status: Standards Track R. Kebler, Ed. 5 Expires: July 25, 2021 Juniper Networks 6 G. Mirsky, Ed. 7 ZTE Corp. 8 January 21, 2021 10 Multicast VPN Fast Upstream Failover 11 draft-ietf-bess-mvpn-fast-failover-15 13 Abstract 15 This document defines Multicast Virtual Private Network (VPN) 16 extensions and procedures that allow fast failover for upstream 17 failures by allowing downstream Provider Edges (PEs) to consider the 18 status of Provider-Tunnels (P-tunnels) when selecting the Upstream PE 19 for a VPN multicast flow. The fast failover is enabled by using RFC 20 8562 Bidirectional Forwarding Detection (BFD) for Multipoint Networks 21 and the new BGP Attribute - BFD Discriminator. Also, the document 22 introduces a new BGP Community, Standby PE, extending BGP Multicast 23 VPN routing so that a C-multicast route can be advertised toward a 24 Standby Upstream PE. 26 Status of This Memo 28 This Internet-Draft is submitted in full conformance with the 29 provisions of BCP 78 and BCP 79. 31 Internet-Drafts are working documents of the Internet Engineering 32 Task Force (IETF). Note that other groups may also distribute 33 working documents as Internet-Drafts. The list of current Internet- 34 Drafts is at https://datatracker.ietf.org/drafts/current/. 36 Internet-Drafts are draft documents valid for a maximum of six months 37 and may be updated, replaced, or obsoleted by other documents at any 38 time. It is inappropriate to use Internet-Drafts as reference 39 material or to cite them other than as "work in progress." 41 This Internet-Draft will expire on July 25, 2021. 43 Copyright Notice 45 Copyright (c) 2021 IETF Trust and the persons identified as the 46 document authors. All rights reserved. 48 This document is subject to BCP 78 and the IETF Trust's Legal 49 Provisions Relating to IETF Documents 50 (https://trustee.ietf.org/license-info) in effect on the date of 51 publication of this document. Please review these documents 52 carefully, as they describe your rights and restrictions with respect 53 to this document. Code Components extracted from this document must 54 include Simplified BSD License text as described in Section 4.e of 55 the Trust Legal Provisions and are provided without warranty as 56 described in the Simplified BSD License. 58 Table of Contents 60 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 61 2. Conventions used in this document . . . . . . . . . . . . . . 4 62 2.1. Requirements Language . . . . . . . . . . . . . . . . . . 4 63 2.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 64 2.3. Acronyms . . . . . . . . . . . . . . . . . . . . . . . . 4 65 3. UMH Selection Based on Tunnel Status . . . . . . . . . . . . 5 66 3.1. Determining the Status of a Tunnel . . . . . . . . . . . 6 67 3.1.1. MVPN Tunnel Root Tracking . . . . . . . . . . . . . . 7 68 3.1.2. PE-P Upstream Link Status . . . . . . . . . . . . . . 7 69 3.1.3. P2MP RSVP-TE Tunnels . . . . . . . . . . . . . . . . 7 70 3.1.4. Leaf-initiated P-tunnels . . . . . . . . . . . . . . 8 71 3.1.5. (C-S, C-G) Counter Information . . . . . . . . . . . 8 72 3.1.6. BFD Discriminator Attribute . . . . . . . . . . . . . 9 73 3.1.7. Per PE-CE Link BFD Discriminator . . . . . . . . . . 13 74 3.1.8. Operational Considerations for Monitoring P-Tunnel's 75 Status . . . . . . . . . . . . . . . . . . . . . . . 13 76 4. Standby C-multicast Route . . . . . . . . . . . . . . . . . . 14 77 4.1. Downstream PE Behavior . . . . . . . . . . . . . . . . . 15 78 4.2. Upstream PE Behavior . . . . . . . . . . . . . . . . . . 16 79 4.3. Reachability Determination . . . . . . . . . . . . . . . 17 80 4.4. Inter-AS . . . . . . . . . . . . . . . . . . . . . . . . 18 81 4.4.1. Inter-AS Procedures for downstream PEs, ASBR Fast 82 Failover . . . . . . . . . . . . . . . . . . . . . . 18 83 4.4.2. Inter-AS Procedures for ASBRs . . . . . . . . . . . . 19 84 5. Hot Root Standby . . . . . . . . . . . . . . . . . . . . . . 19 85 6. Duplicate Packets . . . . . . . . . . . . . . . . . . . . . . 20 86 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20 87 7.1. Standby PE Community . . . . . . . . . . . . . . . . . . 20 88 7.2. BFD Discriminator . . . . . . . . . . . . . . . . . . . . 20 89 7.3. BFD Discriminator Optional TLV Type . . . . . . . . . . . 21 90 8. Security Considerations . . . . . . . . . . . . . . . . . . . 22 91 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 22 92 10. Contributor Addresses . . . . . . . . . . . . . . . . . . . . 22 93 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 24 94 11.1. Normative References . . . . . . . . . . . . . . . . . . 24 95 11.2. Informative References . . . . . . . . . . . . . . . . . 26 97 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 26 99 1. Introduction 101 It is assumed that the reader is familiar with the workings of 102 multicast MPLS/BGP IP VPNs as described in [RFC6513] and [RFC6514]. 104 In the context of multicast in BGP/MPLS VPNs [RFC6513], it is 105 desirable to provide mechanisms allowing fast recovery of 106 connectivity on different types of failures. This document addresses 107 failures of elements in the provider network that are upstream of PEs 108 connected to VPN sites with receivers. 110 Section 3 describes local procedures allowing an egress PE (a PE 111 connected to a receiver site) to take into account the status of 112 P-tunnels to determine the Upstream Multicast Hop (UMH) for a given 113 (C-S, C-G). One of the optional methods uses [RFC8562] and the new 114 BGP Attribute - BFD Discriminator. None of these methods provide a 115 "fast failover" solution when used alone, but can be used together 116 with the mechanism described in Section 4 for a "fast failover" 117 solution. 119 Section 4 describes an optional BGP extension, a new Standby PE 120 Community. that can speed up failover by not requiring any multicast 121 VPN (MVPN) routing message exchange at recovery time. 123 Section 5 describes a "hot leaf standby" mechanism that can be used 124 to improve failover time in MVPN. The approach combines mechanisms 125 defined in Section 3 and Section 4, and has similarities with the 126 solution described in [RFC7431] to improve failover times when PIM 127 routing is used in a network given some topology and metric 128 constraints. 130 The procedures described in this document are optional and allow an 131 operator to provide protection for multicast services in BGP/MPLS IP 132 VPNs. An operator would enable these mechanisms using a method 133 discussed in Section 3 combined with the redundancy provided by a 134 standby PE connected to the multicast flow source. PEs that support 135 these mechanisms would converge faster and thus provide a more stable 136 multicast service. In the case that a BGP implementation does not 137 recognize or is configured not to support the extensions defined in 138 this document, the implementation will continue to provide the 139 multicast service, as described in [RFC6513]. 141 2. Conventions used in this document 143 2.1. Requirements Language 145 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 146 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 147 "OPTIONAL" in this document are to be interpreted as described in BCP 148 14 [RFC2119] [RFC8174] when, and only when, they appear in all 149 capitals, as shown here. 151 2.2. Terminology 153 The terminology used in this document is the terminology defined in 154 [RFC6513] and [RFC6514]. 156 The term 'upstream' (lower case) throughout this document refers to 157 links and nodes that are upstream to a PE connected to VPN sites with 158 receivers of a multicast flow. 160 The term 'Upstream' (capitalized) throughout this document refers to 161 a PE or an Autonomous System Border Router (ASBR) at which (S,G) or 162 (*,G) data packets enter the VPN backbone or the local AS when 163 traveling through the VPN backbone. 165 2.3. Acronyms 167 PMSI: P-Multicast Service Interface 169 I-PMSI: Inclusive PMSI 171 S-PMSI: Selective PMSI 173 x-PMSI: Either an I-PMSI or an S-PMSI 175 P-tunnel: Provider-Tunnels 177 UMH: Upstream Multicast Hop 179 VPN: Virtual Private Network 181 MVPN: Multicast VPN 183 RD: Route Distinguisher 185 RP: Rendezvous Point 187 NLRI: Network Layer Reachability Information 188 VRF: VPN Routing and Forwarding Table 190 MED: Multi-Exit Discriminator 192 P2MP: Point-to-Multipoint 194 3. UMH Selection Based on Tunnel Status 196 Section 5.1 of [RFC6513] describes procedures used by a multicast VPN 197 downstream PE to determine the Upstream Multicast Hop (UMH) for a 198 given (C-S, C-G). 200 For a given downstream PE and a given VRF, the P-tunnel corresponding 201 to a given Upstream PE for a given (C-S, C-G) state is the S-PMSI 202 tunnel advertised by that Upstream PE for this (C-S, C-G) and 203 imported into that VRF, or if there isn't any such S-PMSI, the I-PMSI 204 tunnel advertised by that PE and imported into that VRF. 206 The procedure described here is an optional procedure that is based 207 on a downstream PE taking into account the status of P-tunnels rooted 208 at each possible Upstream PE, for including or not including each 209 given PE in the list of candidate UMHs for a given (C-S, C-G) state. 210 If it is not possible to determine whether a P-tunnel's current 211 status is Up, the state shall be considered "not known to be Down", 212 and it may be treated as if it is Up so that attempts to use the 213 tunnel are acceptable. The result is that, if a P-tunnel is Down 214 (see Section 3.1), the PE that is the root of the P-tunnel will not 215 be considered for UMH selection. This will result in the downstream 216 PE failing over to use the next Upstream PE in the list of 217 candidates. Some downstream PEs could arrive at a different 218 conclusion regarding the tunnel's state because the failure impacts 219 only a subset of branches. Because of that, the procedures of 220 Section 9.1.1 of [RFC6513] are applicable when using I-PMSI 221 P-tunnels. That document is a foundation for this document, and its 222 processes all apply here. 224 There are three options specified in Section 5.1 of [RFC6513] for a 225 downstream PE to select an Upstream PE. 227 o The first two options select the Upstream PE from a candidate PE 228 set either based on an IP address or a hashing algorithm. When 229 used together with the optional procedure of considering the 230 P-tunnel status as in this document, a candidate Upstream PE is 231 included in the set if it either: 233 A. advertises an x-PMSI bound to a tunnel, where the specified 234 tunnel's state is not known to be Down, or, 236 B. does not advertise any x-PMSI applicable to the given (C-S, 237 C-G) but has associated a VRF Route Import BGP Extended 238 Community to the unicast VPN route for S. That is necessary 239 to avoid incorrectly invalidating a UMH PE that would use a 240 policy where no I-PMSI is advertised for a given VRF and where 241 only S-PMSI are used. The S-PMSI can be advertised only after 242 the Upstream PE receives a C-multicast route for (C-S, 243 C-G)/(C-*, C-G) to be carried over the advertised S-PMSI. 245 If the resulting candidate set is empty, then the procedure is 246 repeated without considering the P-tunnel status. 248 o The third option uses the installed UMH Route (i.e., the "best" 249 route towards the C-root) as the Selected UMH Route, and its 250 originating PE is the selected Upstream PE. With the optional 251 procedure of considering P-tunnel status as in this document, the 252 Selected UMH Route is the best one among those whose originating 253 PE's P-tunnel is not "down". If that does not exist, the 254 installed UMH Route is selected regardless of the P-tunnel status. 256 3.1. Determining the Status of a Tunnel 258 Different factors can be considered to determine the "status" of a 259 P-tunnel and are described in the following sub-sections. The 260 optional procedures described in this section also handle the case 261 when the downstream PEs do not all apply the same rules to define 262 what the status of a P-tunnel is (please see Section 6), and some of 263 them will produce a result that may be different for different 264 downstream PEs. Thus, the "status" of a P-tunnel in this section is 265 not a characteristic of the tunnel in itself, but is the tunnel 266 status, as seen from a particular downstream PE. Additionally, some 267 of the following methods determine the ability of a downstream PE to 268 receive traffic on the P-tunnel and not specifically on the status of 269 the P-tunnel itself. That could be referred to as "P-tunnel 270 reception status", but for simplicity, we will use the terminology of 271 P-tunnel "status" for all of these methods. 273 Depending on the criteria used to determine the status of a P-tunnel, 274 there may be an interaction with another resiliency mechanism used 275 for the P-tunnel itself, and the UMH update may happen immediately or 276 may need to be delayed. Each particular case is covered in each 277 separate sub-section below. 279 An implementation may support any combination of the methods 280 described in this section and provide a network operator with control 281 to choose which one to use in the particular deployment. 283 3.1.1. MVPN Tunnel Root Tracking 285 When determining if the status of a P-tunnel is Up, a condition to 286 consider is whether the root of the tunnel, as specified in the 287 x-PMSI Tunnel attribute, is reachable through unicast routing tables. 288 In this case, the downstream PE can immediately update its UMH when 289 the reachability condition changes. 291 That is similar to BGP next-hop tracking for VPN routes, except that 292 the address considered is not the BGP next-hop address but the root 293 address in the x-PMSI Tunnel attribute. BGP next-hop tracking 294 monitors BGP next-hop address changes in the routing table. In 295 general, when a change is detected, it performs a next-hop scan to 296 find if any of the next hops in the BGP table is affected and updates 297 it accordingly. 299 If BGP next-hop tracking is done for VPN routes and the root address 300 of a given tunnel happens to be the same as the next-hop address in 301 the BGP A-D Route advertising the tunnel, then checking, in unicast 302 routing tables, whether the tunnel root is reachable, will be 303 unnecessary duplication and thus will not bring any specific benefit. 305 3.1.2. PE-P Upstream Link Status 307 When determining if the status of a P-tunnel is Up, a condition to 308 consider is whether the last-hop link of the P-tunnel is Up. 309 Conversely, if the last-hop link of the P-tunnel is Down, then this 310 can be taken as an indication that the P-tunnel is Down. 312 Using this method when a fast restoration mechanism (such as MPLS FRR 313 [RFC4090]) is in place for the link requires careful consideration 314 and coordination of defect detection intervals for the link and the 315 tunnel. When using multi-layer protection, particular consideration 316 must be given to the interaction of defect detections at different 317 network layers. It is recommended to use longer detection intervals 318 at the higher layers. Some recommendations suggest using a 319 multiplier of 3 or larger, e.g., 10 msec detection for the link 320 failure detection and at least 100 msec for the tunnel failure 321 detection. In many cases, it is not practical to use both protection 322 methods simultaneously because uncorrelated timers might cause 323 unnecessary switchovers and destabilize the network. 325 3.1.3. P2MP RSVP-TE Tunnels 327 For P-tunnels of type P2MP MPLS-TE, the status of the P-tunnel is 328 considered Up if the sub-LSP to this downstream PE is in the Up 329 state. The determination of whether a P2MP RSVP-TE LSP is in the Up 330 state requires Path and Resv state for the LSP and is based on 331 procedures specified in [RFC4875]. As a result, the downstream PE 332 can immediately update its UMH when the reachability condition 333 changes. 335 When using this method and if the signaling state for a P2MP TE LSP 336 is removed (e.g., if the ingress of the P2MP TE LSP sends a PathTear 337 message) or the P2MP TE LSP changes state from Up to Down as 338 determined by procedures in [RFC4875], the status of the 339 corresponding P-tunnel MUST be re-evaluated. If the P-tunnel 340 transitions from Up to Down state, the Upstream PE that is the 341 ingress of the P-tunnel MUST NOT be considered as a valid candidate 342 UMH. 344 3.1.4. Leaf-initiated P-tunnels 346 An Upstream PE MUST be removed from the UMH candidate list for a 347 given (C-S, C-G) if the P-tunnel (I-PMSI or S-PMSI) for this (S, G) 348 is leaf-triggered (PIM, mLDP), but for some reason, internal to the 349 protocol, the upstream one-hop branch of the tunnel from P to PE 350 cannot be built. As a result, the downstream PE can immediately 351 update its UMH when the reachability condition changes. 353 3.1.5. (C-S, C-G) Counter Information 355 In cases where the downstream node can be configured so that the 356 maximum inter-packet time is known for all the multicast flows mapped 357 on a P-tunnel, the local per-(C-S, C-G) traffic counter information 358 for traffic received on this P-tunnel can be used to determine the 359 status of the P-tunnel. 361 When such a procedure is used, in the context where fast restoration 362 mechanisms are used for the P-tunnels, a configurable timer MUST be 363 set on the downstream PE to wait before updating the UMH to let the 364 P-tunnel restoration mechanism execute its actions. Determining that 365 a tunnel is probably down by waiting for enough packets to fail to 366 arrive as expected is a heuristic and operational matter that depends 367 on the maximum inter-packet time. A timeout of three seconds is a 368 generally suitable default waiting period to ascertain that the 369 tunnel is down, though other values would be needed for atypical 370 conditions. 372 In cases where this mechanism is used in conjunction with the method 373 described in Section 5, no prior knowledge of the rate or maximum 374 inter-packet time on the multicast streams is required; downstream 375 PEs can periodically compare actual packet reception statistics on 376 the two P-tunnels to determine when one of them is down. The 377 detailed specification of this mechanism is outside the scope of this 378 document. 380 3.1.6. BFD Discriminator Attribute 382 The P-tunnel status may be derived from the status of a multipoint 383 BFD session [RFC8562] whose discriminator is advertised along with an 384 x-PMSI A-D Route. A P2MP BFD session can be instantiated using a 385 mechanism other than the BFD Discriminator attribute, e.g., MPLS LSP 386 Ping ([I-D.mirsky-mpls-p2mp-bfd]). The description of these methods 387 is outside the scope of this document. 389 This document defines the format and ways of using a new BGP 390 attribute called the "BFD Discriminator". It is an optional 391 transitive BGP attribute. Thus it is expected that an implementation 392 that does not recognize or is configured not to support this 393 attribute, as if the attribute was unrecognized, follows procedures 394 defined for optional transitive path attributes in Section 5 of 395 [RFC4271]. In Section 7.2, IANA is requested to allocate the 396 codepoint value (TBA2). The format of this attribute is shown in 397 Figure 1. 399 0 1 2 3 400 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 1 401 +-+-+-+-+-+-+-+-+ 402 | BFD Mode | 403 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 404 | BFD Discriminator | 405 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 406 ~ Optional TLVs ~ 407 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 409 Figure 1: Format of the BFD Discriminator Attribute 411 Where: 413 BFD Mode field is one octet long. This specification defines the 414 P2MP BFD Session as value 1 Section 7.2. 416 BFD Discriminator field is four octets long. 418 Optional TLVs is the optional variable-length field that MAY be 419 used in the BFD Discriminator attribute for future extensions. 420 TLVs MAY be included in a sequential or nested manner. To allow 421 for TLV nesting, it is advised to define a new TLV as a variable- 422 length object. Figure 2 presents the Optional TLV format TLV that 423 consists of: 425 * Type - a one-octet-long field that characterizes the 426 interpretation of the Value field (Section 7.3) 428 * Length - a one-octet-long field equal to the length of the 429 Value field in octets 431 * Value - a variable-length field. 433 All multibyte fields in TLVs defined in this specification are in 434 network byte order. 436 0 1 2 3 437 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 1 438 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 439 | Type | Length | Value ... 440 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 442 Figure 2: Format of the Optional TLV 444 An optional Source IP Address TLV is defined in this document. The 445 Source IP Address TLV MUST be used when the value of the BFD Mode 446 field's value is P2MP BFD Session. The BFD Discriminator attribute 447 that does not include the Source IP Address TLV MUST be handled 448 according to the "attribute discard" approach, as defined in 449 [RFC7606]. For the Source IP Address TLV fields are set as follows: 451 o The Type field is set to 1 Section 7.3. 453 o The Length field is 4 for the IPv4 address family and 16 for the 454 IPv6 address family. The TLV is considered malformed if the field 455 is set to any other value. 457 o The Value field contains the address associated with the 458 MultipointHead of the P2MP BFD session. 460 The BFD Discriminator attribute MUST be considered malformed if its 461 length is smaller than 11 octets or if Optional TLVs are present, but 462 not well-formed. If the attribute is deemed to be malformed, the 463 UPDATE message SHALL be handled using the approach of Attribute 464 Discard per [RFC7606]. 466 3.1.6.1. Upstream PE Procedures 468 To enable downstream PEs to track the P-tunnel status using a point- 469 to-multipoint (P2MP) BFD session the Upstream PE: 471 o MUST initiate the BFD session and set bfd.SessionType = 472 MultipointHead as described in [RFC8562]; 474 o when transmitting BFD Control packets MUST set the IP destination 475 address of the inner IP header to the internal loopback address 476 127.0.0.1/32 for IPv4 [RFC1122]. For IPv6, it MUST use the 477 loopback address ::1/128 [RFC4291]. 479 o MUST use the IP address included in the Source IP Address TLV of 480 the BFD Discriminator attribute as the source IP address when 481 transmitting BFD Control packets; 483 o MUST include the BFD Discriminator attribute in the x-PMSI A-D 484 Route with the value set to My Discriminator value; 486 o MUST periodically transmit BFD Control packets over the x-PMSI 487 P-tunnel after the P-tunnel is considered established. Note that 488 the methods to declare that a P-tunnel has been established are 489 outside the scope of this specification. 491 If the tracking of the P-tunnel by using a P2MP BFD session is 492 enabled after the x-PMSI A-D Route has been already advertised, the 493 x-PMSI A-D Route MUST be re-sent with the only change between the 494 previous advertisement and the new advertisement to be the inclusion 495 of the BFD Discriminator attribute. 497 If the x-PMSI A-D Route is advertised with P-tunnel status tracked 498 using the P2MP BFD session, and it is desired to stop tracking 499 P-tunnel status using BFD, then: 501 o x-PMSI A-D Route MUST be re-sent with the only change between the 502 previous advertisement and the new advertisement be the exclusion 503 of the BFD Discriminator attribute; 505 o the P2MP BFD session MUST be deleted. The session MAY be deleted 506 after some configurable delay, which should have a reasonable 507 default. 509 3.1.6.2. Downstream PE Procedures 511 Upon receiving the BFD Discriminator attribute in the x-PMSI A-D 512 Route, the downstream PE: 514 o MUST associate the received BFD Discriminator value with the 515 P-tunnel originating from the Upstream PE and the IP address of 516 the Upstream PE; 518 o MUST create a P2MP BFD session and set bfd.SessionType = 519 MultipointTail as described in [RFC8562]; 521 o to properly demultiplex BFD session MUST use: 523 the IP address in the Source IP Address TLV included the BFD 524 Discriminator attribute in the x-PMSI A-D Route; 526 the value of the BFD Discriminator field in the BFD 527 Discriminator attribute; 529 the x-PMSI Tunnel Identifier [RFC6514] the BFD Control packet 530 was received on. 532 After the state of the P2MP BFD session is up, i.e., bfd.SessionState 533 == Up, the session state will then be used to track the health of the 534 P-tunnel. 536 According to [RFC8562], if the downstream PE receives Down or 537 AdminDown in the State field of the BFD Control packet or associated 538 with the BFD session Detection Timer associated with the BFD session 539 expires, the BFD session is down, i.e., bfd.SessionState == Down. 540 When the BFD session state is Down, then the P-tunnel associated with 541 the BFD session MUST be considered down. If the site that contains 542 C-S is connected to two or more PEs, a downstream PE will select one 543 as its Primary Upstream PE, while others are considered as Standby 544 Upstream PEs. In such a scenario, when the P-tunnel is considered 545 down, the downstream PE MAY initiate a switchover of the traffic from 546 the Primary Upstream PE to the Standby Upstream PE only if the 547 Standby Upstream PE is deemed to be in the Up state. That MAY be 548 determined from the state of a P2MP BFD session with the Standby 549 Upstream PE as the MultipointHead. 551 If the downstream PE's P-tunnel is already established when the 552 downstream PE receives the new x-PMSI A-D Route with BFD 553 Discriminator attribute, the downstream PE MUST associate the value 554 of BFD Discriminator field with the P-tunnel and follow procedures 555 listed above in this section if and only if the x-PMSI A-D Route was 556 properly processed as per [RFC6514], and the BFD Discriminator 557 attribute was validated. 559 If the downstream PE's P-tunnel is already established, its state 560 being monitored by the P2MP BFD session set up using the BFD 561 Discriminator attribute, and the downstream PE receives the new 562 x-PMSI A-D Route without the BFD Discriminator attribute, and the 563 x-PMSI A-D Route was processed without any error as per the relevant 564 specifications, the downstream PE: 566 o MUST stop processing BFD Control packets for this P2MP BFD 567 session; 569 o the P2MP BFD session associated with the P-tunnel MUST be deleted. 570 The session MAY be deleted after some configurable delay, which 571 should have a reasonable default. 573 o MUST NOT switch the traffic to the Standby Upstream PE. 575 3.1.7. Per PE-CE Link BFD Discriminator 577 The following approach is defined in response to the detection by the 578 Upstream PE of a PE-CE link failure. Even though the provider tunnel 579 is still up, it is desired for the downstream PEs to switch to a 580 backup Upstream PE. To achieve that, if the Upstream PE detects that 581 its PE-CE link fails, it MUST set the bfd.LocalDiag of the P2MP BFD 582 session to Concatenated Path Down or Reverse Concatenated Path Down 583 (per Section 6.8.17 [RFC5880]), unless it switches to a new PE- CE 584 link within the time of bfd.DesiredMinTxInterval for the P2MP BFD 585 session (in that case, the Upstream PE will start tracking the status 586 of the new PE-CE link). When a downstream PE receives that 587 bfd.LocalDiag code, it treats it as if the tunnel itself failed and 588 tries to switch to a backup PE. 590 3.1.8. Operational Considerations for Monitoring P-Tunnel's Status 592 Several methods to monitor the status of a P-tunnel are described in 593 Section 3.1. 595 Tracking the root of an MVPN (Section 3.1.1) concludes about the 596 status of a P-tunnel based on the control plane information. 597 Because, in general, the MPLS data plane is not fate-sharing with the 598 control plane, this method might produce false positive or false 599 negative alarms, For example, resulting in tunnels that considered as 600 being up but are not able to reach the root, or ones that are 601 declared down prematurely. On the other hand, because BGP next-hop 602 tracking is broadly supported and deployed, this method might be the 603 easiest to deploy. 605 Method described in Section 3.1.2 monitors the state of the data 606 plane but only for an egress P-PE link of a P-tunnel. As a result, 607 network failures that affect upstream links might not be detected 608 using this method and the MVPN convergence would be determined by the 609 convergence of the BGP control plane. 611 Using the state change of a P2MP RSVP-TE LSP as the trigger to re- 612 evaluate the status of the P-tunnel (Section 3.1.3) relies on the 613 mechanism used to monitor the state of the P2MP LSP. 615 The method described in Section 3.1.4 is simple and is safe from 616 causing false alarms, e.g., considering a tunnel operationally up 617 even though its data path has a defect or, conversely, declaring a 618 tunnel failed when it is unaffected. But the method applies to a 619 sub-set of MVPNs, those that use the leaf-triggered x-PMSI tunnels. 621 Though some MVPN might be used to provide a multicast service with 622 predictable interpacket interval (Section 3.1.5), the number of such 623 cases seem limited. 625 Monitoring the status of a P-tunnel using p2mp BFD session 626 (Section 3.1.6) may produce the most accurate and expedient failure 627 notification of all monitoring methods discussed. On the other hand, 628 it requires careful consideration of the additional load of BFD onto 629 network and PE nodes. Operators should consider the rate of BFD 630 Control packets transmitted by root PEs combined with the number of 631 such PEs in the network. In addition, the number of P2MP BFD 632 sessions per PE determines the amount of state information that a PE 633 maintains. 635 4. Standby C-multicast Route 637 The procedures described below are limited to the case where the site 638 that contains C-S is connected to two or more PEs, though, to 639 simplify the description, the case of dual-homing is described. In 640 the case where more than two PEs are connected to the C-s site, 641 selection of the Standby PE can be performed using one of the methods 642 of selecting a UMH. Details of the selection are outside the scope 643 of this document. The procedures require all the PEs of that MVPN to 644 follow the same UMH selection procedure, as specified in [RFC6513], 645 whether the PE selected based on its IP address, the hashing 646 algorithm described in section 5.1.3 of [RFC6513], or Installed UMH 647 Route. The consistency of the UMH selection method used among all 648 PEs is expected to be provided by the management plane. The 649 procedures assume that if a site of a given MVPN that contains C-S is 650 dual-homed to two PEs, then all the other sites of that MVPN would 651 have two unicast VPN routes (VPN-IPv4 or VPN-IPv6) to C-S, each with 652 its own RD. 654 As long as C-S is reachable via both PEs, a given downstream PE will 655 select one of the PEs connected to C-S as its Upstream PE for C-S. 656 We will refer to the other PE connected to C-S as the "Standby 657 Upstream PE". Note that if the connectivity to C-S through the 658 Primary Upstream PE becomes unavailable, then the PE will select the 659 Standby Upstream PE as its Upstream PE for C-S. When the Primary PE 660 later becomes available, then the PE will select the Primary Upstream 661 PE again as its Upstream PE. Such behavior is referred to as 662 "revertive" behavior and MUST be supported. Non-revertive behavior 663 refers to the behavior of continuing to select the backup PE as the 664 UMH even after the Primary has come up. This non-revertive behavior 665 MAY also be supported by an implementation and would be enabled 666 through some configuration. Selection of the behavior, revertive or 667 non-revertive, is an operational issue, but it MUST be consistent on 668 all PEs in the given MVPN. While revertive is considered the default 669 behavior, there might be cases where the switchover to the standby 670 tunnel does not affect other services and provides the required 671 quality of service. An operator might use non-revertive behavior to 672 avoid unnecessary in such case switchover and thus minimize 673 disruption to the multicast service. 675 For readability, in the following sub-sections, the procedures are 676 described for BGP C-multicast Source Tree Join routes, but they apply 677 equally to BGP C-multicast Shared Tree Join routes for the case where 678 the customer RP is dual-homed (substitute "C-RP" to "C-S"). 680 4.1. Downstream PE Behavior 682 When a (downstream) PE connected to some site of an MVPN needs to 683 send a C-multicast route (C-S, C-G), then following the procedures 684 specified in Section 11.1 of [RFC6514], the PE sends the C-multicast 685 route with an RT that identifies the Upstream PE selected by the PE 686 originating the route. As long as C-S is reachable via the Primary 687 Upstream PE, the Upstream PE is the Primary Upstream PE. If C-S is 688 reachable only via the Standby Upstream PE, then the Upstream PE is 689 the Standby Upstream PE. 691 If C-S is reachable via both the Primary and the Standby Upstream PE, 692 then in addition to sending the C-multicast route with an RT that 693 identifies the Primary Upstream PE, the downstream PE also originates 694 and sends a C-multicast route with an RT that identifies the Standby 695 Upstream PE. The route that has the semantics of being a "standby" 696 C-multicast route is further called a "Standby BGP C-multicast 697 route", and is constructed as follows: 699 o the NLRI is constructed as the C-multicast route with an RT that 700 identifies the Primary Upstream PE, except that the RD is the same 701 as if the C-multicast route was built using the Standby Upstream 702 PE as the UMH (it will carry the RD associated to the unicast VPN 703 route advertised by the Standby Upstream PE for S and a Route 704 Target derived from the Standby Upstream PE's UMH route's VRF RT 705 Import EC); 707 o MUST carry the "Standby PE" BGP Community (this is a new BGP 708 Community. Section 7.1 requested IANA to allocate value TBA1). 710 The Local Preference attribute of the normal and the standby 711 C-multicast route needs to be adjusted. so that, if a BGP peer 712 receives two C-multicast routes with the same NLRI, one carrying the 713 "Standby PE" community and the other one not carrying the "Standby 714 PE" community, then preference is given to the one not carrying the 715 "Standby PE" community. Such a situation can happen when, for 716 instance, due to transient unicast routing inconsistencies or lack of 717 support of the Standby PE community, two different downstream PEs 718 consider different Upstream PEs to be the primary one. In that case, 719 without any precaution taken, both Upstream PEs would process a 720 standby C-multicast route and possibly stop forwarding at the same 721 time. For this purpose, routes that carry the Standby PE BGP 722 Community must have the LOCAL_PREF attribute set to the value lower 723 than the value specified as the LOCAL_PREF attribute for the route 724 that does not carry the Standby PE BGP Community. The value of zero 725 is RECOMMENDED. 727 Note that, when a PE advertises such a Standby C-multicast join for a 728 (C-S, C-G) it MUST join the corresponding P-tunnel. 730 If, at some later point, the PE determines that C-S is no longer 731 reachable through the Primary Upstream PE, the Standby Upstream PE 732 becomes the Upstream PE, and the PE re-sends the C-multicast route 733 with RT that identifies the Standby Upstream PE, except that now the 734 route does not carry the Standby PE BGP Community (which results in 735 replacing the old route with a new route, with the only difference 736 between these routes being the absence of the Standby PE BGP 737 Community). The new Upstream PE must set the LOCAL_PREF attribute 738 for that C-multicast route to the same value as when the Standby PE 739 BGP Community was included in the advertisement. 741 4.2. Upstream PE Behavior 743 When a PE supporting this specification receives a C-multicast route 744 for a particular (C-S, C-G) for which all of the following are true: 746 o the RT carried in the route results in importing the route into a 747 particular VRF on the PE; 749 o the route carries the Standby PE BGP Community; and 751 o the PE determines (via a method of failure detection that is 752 outside the scope of this document) that C-S is not reachable 753 through some other PE (more details are in Section 4.3), 755 then the PE MAY install VRF PIM state corresponding to this Standby 756 BGP C-multicast route (the result will be that a PIM Join message 757 will be sent to the CE towards C-S, and that the PE will receive 758 (C-S, C-G) traffic), and the PE MAY forward (C-S, C-G) traffic 759 received by the PE to other PEs through a P-tunnel rooted at the PE. 761 Furthermore, irrespective of whether C-S carried in that route is 762 reachable through some other PE: 764 a) based on local policy, as soon as the PE receives this Standby BGP 765 C-multicast route, the PE MAY install VRF PIM state corresponding 766 to this BGP Source Tree Join route (the result will be that Join 767 messages will be sent to the CE toward C-S, and that the PE will 768 receive (C-S, C-G) traffic) 770 b) based on local policy, as soon as the PE receives this Standby BGP 771 C-multicast route, the PE MAY forward (C-S, C-G) traffic to other 772 PEs through a P-tunnel independently of the reachability of C-S 773 through some other PE. [note that this implies also doing a)] 775 Doing neither a) or b) for a given (C-S, C-G) is called "cold root 776 standby". 778 Doing a) but not b) for a given (C-S, C-G) is called "warm root 779 standby". 781 Doing b) (which implies also doing a)) for a given (C-S, C-G) is 782 called "hot root standby". 784 Note that, if an Upstream PE uses an S-PMSI only policy, it shall 785 advertise an S-PMSI for a (C-S, C-G) as soon as it receives a 786 C-multicast route for (C-S, C-G), normal or Standby; i.e., it shall 787 not wait for receiving a non-Standby C-multicast route before 788 advertising the corresponding S-PMSI. 790 Section 9.3.2 of [RFC6513], describes the procedures of sending a 791 Source-Active A-D Route as a result of receiving the C-multicast 792 route. These procedures MUST be followed for both the normal and 793 Standby C-multicast routes. 795 4.3. Reachability Determination 797 The Standby Upstream PE can use the following information to 798 determine that C-S can or cannot be reached through the Primary 799 Upstream PE: 801 o presence/absence of a unicast VPN route toward C-S 802 o supposing that the Standby Upstream PE is the egress of the tunnel 803 rooted at the Primary Upstream PE, the Standby Upstream PE can 804 determine the reachability of C-S through the Primary Upstream PE 805 based on the status of this tunnel, determined thanks to the same 806 criteria as the ones described in Section 3.1 (without using the 807 UMH selection procedures of Section 3); 809 o other mechanisms may be used. 811 4.4. Inter-AS 813 If the non-segmented inter-AS approach is used, the procedures 814 described in Section 4.1 through Section 4.3 can be applied. 816 When multicast VPNs are used in an inter-AS context with the 817 segmented inter-AS approach described in Section 9.2 of [RFC6514], 818 the procedures in this section can be applied. 820 A pre-requisite for the procedures described below to be applied for 821 a source of a given MVPN is: 823 o that any PE of this MVPN receives two or more Inter-AS I-PMSI A-D 824 Routes advertised by the AS of the source 826 o that these Inter-AS I-PMSI A-D Routes have distinct Route 827 Distinguishers (as described in item "(2)" of section 9.2 of 828 [RFC6514]). 830 As an example, these conditions will be satisfied when the source is 831 dual-homed to an AS that connects to the receiver AS through two ASBR 832 using auto-configured RDs. 834 4.4.1. Inter-AS Procedures for downstream PEs, ASBR Fast Failover 836 The following procedure is applied by downstream PEs of an AS, for a 837 source S in a remote AS. 839 Additionally to choosing an Inter-AS I-PMSI A-D Route advertised from 840 the AS of the source to construct a C-multicast route, as described 841 in section 11.1.3 [RFC6514], a downstream PE will choose a second 842 Inter-AS I-PMSI A-D Route advertised from the AS of the source and 843 use this route to construct and advertise a Standby C-multicast route 844 (C-multicast route carrying the Standby extended community), as 845 described in Section 4.1. 847 4.4.2. Inter-AS Procedures for ASBRs 849 When an Upstream ASBR receives a C-multicast route, and at least one 850 of the RTs of the route matches one of the ASBR Import RT, the ASBR, 851 that supports this specification, must try to locate an Inter-AS 852 I-PMSI A-D Route whose RD and Source AS respectively match the RD and 853 Source AS carried in the C-multicast route. If the match is found, 854 and the C-multicast route carries the Standby PE BGP Community, then 855 the ASBR implementation that supports this specification MUST be 856 configurable to perform as follows: 858 o if the route was received over iBGP and its LOCAL_PREF attribute 859 is set to zero, then it MUST be re-advertised in eBGP with a MED 860 attribute (MULTI_EXIT_DISC) set to the highest possible value 861 (0xffff) 863 o if the route was received over eBGP and its MED attribute set to 864 0xffff, then it MUST be re-advertised in iBGP with a LOCAL_PREF 865 attribute set to zero 867 Other ASBR procedures are applied without modification and, when 868 applied, MAY modify the above-listed behavior. 870 5. Hot Root Standby 872 The mechanisms defined in Section 4 and Section 3 can be used 873 together as follows. 875 The principle is that, for a given VRF (or possibly only for a given 876 (C-S, C-G): 878 o downstream PEs advertise a Standby BGP C-multicast route (based on 879 Section 4) 881 o Upstream PEs use the "hot standby" optional behavior and thus will 882 start forwarding traffic for a given multicast state after they 883 have a (primary) BGP C-multicast route or a Standby BGP 884 C-multicast route for that state (or both) 886 o a policy controls downstream PEs from which tunnel to accept 887 traffic. For example, the policy could be based on the status of 888 the tunnel or tunnel monitoring method (Section 3.1.5). 890 Other combinations of the mechanisms proposed in Section 4 and 891 Section 3 are for further study. 893 Note that the same level of protection would be achievable with a 894 simple C-multicast Source Tree Join route advertised to both the 895 primary and secondary Upstream PEs (carrying as Route Target extended 896 communities, the values of the VRF Route Import Extended Community of 897 each VPN route from each Upstream PEs). The advantage of using the 898 Standby semantic is that, supposing that downstream PEs always 899 advertise a Standby C-multicast route to the secondary Upstream PE, 900 it allows to choose the protection level through a change of 901 configuration on the secondary Upstream PE, without requiring any 902 reconfiguration of all the downstream PEs. 904 6. Duplicate Packets 906 Multicast VPN specifications [RFC6513] impose that a PE only forwards 907 to CEs the packets coming from the expected Upstream PE (Section 9.1 908 of [RFC6513]). 910 We draw the reader's attention to the fact that the respect of this 911 part of multicast VPN specifications is especially important when two 912 distinct Upstream PEs are susceptible to forward the same traffic on 913 P-tunnels at the same time in the steady state. That will be the 914 case when "hot root standby" mode is used (Section 5), and which can 915 also be the case if procedures of Section 3 are used and a) the rules 916 determining the status of a tree are not the same on two distinct 917 downstream PEs or b) the rule determining the status of a tree 918 depends on conditions local to a PE (e.g., the PE-P upstream link 919 being up). 921 7. IANA Considerations 923 7.1. Standby PE Community 925 IANA is requested to allocate the BGP "Standby PE" community value 926 (TBA1) from the Border Gateway Protocol (BGP) Well-known Communities 927 registry using the First Come First Served registration policy. 929 7.2. BFD Discriminator 931 This document defines a new BGP optional transitive attribute, called 932 "BFD Discriminator". IANA is requested to allocate a codepoint 933 (TBA2) in the "BGP Path Attributes" registry to the BFD Discriminator 934 attribute. 936 IANA is requested to create a new BFD Mode sub-registry in the Border 937 Gateway Protocol (BGP) Parameters registry. The registration 938 policies, per [RFC8126], for this sub-registry are according to 939 Table 1. 941 +-----------+-------------------------+ 942 | Value | Policy | 943 +-----------+-------------------------+ 944 | 0- 175 | IETF Review | 945 | 176 - 249 | First Come First Served | 946 | 250 - 254 | Experimental Use | 947 | 255 | IETF Review | 948 +-----------+-------------------------+ 950 Table 1: BFD Mode Sub-registry Registration Policies 952 IANA is requested to make initial assignments according to Table 2. 954 +-----------+------------------+---------------+ 955 | Value | Description | Reference | 956 +-----------+------------------+---------------+ 957 | 0 | Reserved | This document | 958 | 1 | P2MP BFD Session | This document | 959 | 2- 175 | Unassigned | | 960 | 176 - 249 | Unassigned | | 961 | 250 - 254 | Experimental Use | This document | 962 | 255 | Reserved | This document | 963 +-----------+------------------+---------------+ 965 Table 2: BFD Mode Sub-registry 967 7.3. BFD Discriminator Optional TLV Type 969 IANA is requested to create a new BFD Discriminator Optional TLV Type 970 sub-registry in Border Gateway Protocol (BGP). The registration 971 policies, per [RFC8126], for this sub-registry are according to 972 Table 3. 974 +-----------+-------------------------+ 975 | Value | Policy | 976 +-----------+-------------------------+ 977 | 0- 175 | IETF Review | 978 | 176 - 249 | First Come First Served | 979 | 250 - 254 | Experimental Use | 980 | 255 | IETF Review | 981 +-----------+-------------------------+ 983 Table 3: BFD Discriminator Optional TLV Type Sub-registry 984 Registration Policies 986 IANA is requested to make initial assignments according to Table 4. 988 +-----------+-------------------+---------------+ 989 | Value | Description | Reference | 990 +-----------+-------------------+---------------+ 991 | 0 | Reserved | This document | 992 | 1 | Source IP Address | This document | 993 | 2- 175 | Unassigned | | 994 | 176 - 249 | Unassigned | | 995 | 250 - 254 | Experimental Use | This document | 996 | 255 | Reserved | This document | 997 +-----------+-------------------+---------------+ 999 Table 4: BFD Discriminator Optional TLV Type Sub-registry 1001 8. Security Considerations 1003 This document describes procedures based on [RFC6513] and [RFC6514] 1004 and hence shares the security considerations respectively represented 1005 in these specifications. 1007 This document uses P2MP BFD, as defined in [RFC8562], which, in turn, 1008 is based on [RFC5880]. Security considerations relevant to each 1009 protocol are discussed in the respective protocol specifications. An 1010 implementation that supports this specification MUST provide a 1011 mechanism to limit the overall amount of capacity used by the BFD 1012 traffic (as the combination of the number of active P2MP BFD sessions 1013 and the rate of BFD Control packets to process). 1015 The methods described in Section 3.1 may produce false-negative state 1016 changes that can be the trigger for an unnecessary convergence in the 1017 control plane, ultimately negatively impacting the multicast service 1018 provided by the VPN. An operator is expected to consider the network 1019 environment and use available controls of the mechanism used to 1020 determine the status of a P-tunnel. 1022 9. Acknowledgments 1024 The authors want to thank Greg Reaume, Eric Rosen, Jeffrey Zhang, 1025 Martin Vigoureux, Adrian Farrel, and Zheng (Sandy) Zhang for their 1026 reviews, useful comments, and helpful suggestions. 1028 10. Contributor Addresses 1030 Below is a list of other contributing authors in alphabetical order: 1032 Rahul Aggarwal 1033 Arktan 1035 Email: raggarwa_1@yahoo.com 1036 Nehal Bhau 1037 Cisco 1039 Email: NBhau@cisco.com 1041 Clayton Hassen 1042 Bell Canada 1043 2955 Virtual Way 1044 Vancouver 1045 CANADA 1047 Email: Clayton.Hassen@bell.ca 1049 Wim Henderickx 1050 Nokia 1051 Copernicuslaan 50 1052 Antwerp 2018 1053 Belgium 1055 Email: wim.henderickx@nokia.com 1057 Pradeep Jain 1058 Nokia 1059 701 E Middlefield Rd 1060 Mountain View, CA 94043 1061 USA 1063 Email: pradeep.jain@nokia.com 1065 Jayant Kotalwar 1066 Nokia 1067 701 E Middlefield Rd 1068 Mountain View, CA 94043 1069 USA 1071 Email: Jayant.Kotalwar@nokia.com 1073 Praveen Muley 1074 Nokia 1075 701 East Middlefield Rd 1076 Mountain View, CA 94043 1077 U.S.A. 1079 Email: praveen.muley@nokia.com 1081 Ray (Lei) Qiu 1082 Juniper Networks 1083 1194 North Mathilda Ave. 1084 Sunnyvale, CA 94089 1085 U.S.A. 1087 Email: rqiu@juniper.net 1089 Yakov Rekhter 1090 Juniper Networks 1091 1194 North Mathilda Ave. 1092 Sunnyvale, CA 94089 1093 U.S.A. 1095 Email: yakov@juniper.net 1097 Kanwar Singh 1098 Nokia 1099 701 E Middlefield Rd 1100 Mountain View, CA 94043 1101 USA 1103 Email: kanwar.singh@nokia.com 1105 11. References 1107 11.1. Normative References 1109 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1110 Requirement Levels", BCP 14, RFC 2119, 1111 DOI 10.17487/RFC2119, March 1997, 1112 . 1114 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 1115 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 1116 DOI 10.17487/RFC4271, January 2006, 1117 . 1119 [RFC4875] Aggarwal, R., Ed., Papadimitriou, D., Ed., and S. 1120 Yasukawa, Ed., "Extensions to Resource Reservation 1121 Protocol - Traffic Engineering (RSVP-TE) for Point-to- 1122 Multipoint TE Label Switched Paths (LSPs)", RFC 4875, 1123 DOI 10.17487/RFC4875, May 2007, 1124 . 1126 [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection 1127 (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010, 1128 . 1130 [RFC6513] Rosen, E., Ed. and R. Aggarwal, Ed., "Multicast in MPLS/ 1131 BGP IP VPNs", RFC 6513, DOI 10.17487/RFC6513, February 1132 2012, . 1134 [RFC6514] Aggarwal, R., Rosen, E., Morin, T., and Y. Rekhter, "BGP 1135 Encodings and Procedures for Multicast in MPLS/BGP IP 1136 VPNs", RFC 6514, DOI 10.17487/RFC6514, February 2012, 1137 . 1139 [RFC7606] Chen, E., Ed., Scudder, J., Ed., Mohapatra, P., and K. 1140 Patel, "Revised Error Handling for BGP UPDATE Messages", 1141 RFC 7606, DOI 10.17487/RFC7606, August 2015, 1142 . 1144 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 1145 Writing an IANA Considerations Section in RFCs", BCP 26, 1146 RFC 8126, DOI 10.17487/RFC8126, June 2017, 1147 . 1149 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1150 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1151 May 2017, . 1153 [RFC8562] Katz, D., Ward, D., Pallagatti, S., Ed., and G. Mirsky, 1154 Ed., "Bidirectional Forwarding Detection (BFD) for 1155 Multipoint Networks", RFC 8562, DOI 10.17487/RFC8562, 1156 April 2019, . 1158 11.2. Informative References 1160 [I-D.mirsky-mpls-p2mp-bfd] 1161 Mirsky, G., Mishra, G., and D. Eastlake, "BFD for 1162 Multipoint Networks over Point-to-Multi-Point MPLS LSP", 1163 draft-mirsky-mpls-p2mp-bfd-12 (work in progress), November 1164 2020. 1166 [RFC1122] Braden, R., Ed., "Requirements for Internet Hosts - 1167 Communication Layers", STD 3, RFC 1122, 1168 DOI 10.17487/RFC1122, October 1989, 1169 . 1171 [RFC4090] Pan, P., Ed., Swallow, G., Ed., and A. Atlas, Ed., "Fast 1172 Reroute Extensions to RSVP-TE for LSP Tunnels", RFC 4090, 1173 DOI 10.17487/RFC4090, May 2005, 1174 . 1176 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 1177 Architecture", RFC 4291, DOI 10.17487/RFC4291, February 1178 2006, . 1180 [RFC7431] Karan, A., Filsfils, C., Wijnands, IJ., Ed., and B. 1181 Decraene, "Multicast-Only Fast Reroute", RFC 7431, 1182 DOI 10.17487/RFC7431, August 2015, 1183 . 1185 Authors' Addresses 1187 Thomas Morin (editor) 1188 Orange 1189 2, avenue Pierre Marzin 1190 Lannion 22307 1191 France 1193 Email: thomas.morin@orange-ftgroup.com 1195 Robert Kebler (editor) 1196 Juniper Networks 1197 1194 North Mathilda Ave. 1198 Sunnyvale, CA 94089 1199 U.S.A. 1201 Email: rkebler@juniper.net 1202 Greg Mirsky (editor) 1203 ZTE Corp. 1205 Email: gregimirsky@gmail.com