idnits 2.17.1 draft-morin-l3vpn-mvpn-fast-failover-05.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 : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == Using lowercase 'not' together with uppercase 'MUST', 'SHALL', 'SHOULD', or 'RECOMMENDED' is not an accepted usage according to RFC 2119. Please use uppercase 'NOT' together with RFC 2119 keywords (if that is what you mean). Found 'SHOULD not' in this paragraph: [RFC4875], the status of the corresponding P-Tunnel SHOULD be re-evaluated. If the P-Tunnel transitions from up to down state, the upstream PE, that is the ingress of the P-Tunnel, SHOULD not be considered a valid UMH. -- The document seems to lack a disclaimer for pre-RFC5378 work, but may have content which was first submitted before 10 November 2008. If you have contacted all the original authors and they are all willing to grant the BCP78 rights to the IETF Trust, then this is fine, and you can ignore this comment. If not, you may need to add the pre-RFC5378 disclaimer. (See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (March 14, 2011) is 4785 days in the past. Is this intentional? Checking references for intended status: Experimental ---------------------------------------------------------------------------- == Outdated reference: A later version (-02) exists of draft-karan-mofrr-01 Summary: 0 errors (**), 0 flaws (~~), 3 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group T. Morin 3 Internet-Draft France Telecom - Orange Labs 4 Intended status: Experimental Y. Rekhter 5 Expires: September 15, 2011 R. Aggarwal 6 Juniper Networks 7 W. Henderickx 8 P. Muley 9 Alcatel-Lucent 10 R. Qiu 11 Huawei 12 March 14, 2011 14 Multicast VPN fast upstream failover 15 draft-morin-l3vpn-mvpn-fast-failover-05 17 Abstract 19 This document defines multicast VPN extensions and procedures that 20 allow fast failover for upstream failures, by allowing downstream PEs 21 to take into account the status of Provider-Tunnels (P-tunnels) when 22 selecting the upstream PE for a VPN multicast flow, and extending BGP 23 MVPN routing so that a C-multicast route can be advertized toward a 24 standby upstream PE. 26 Requirements Language 28 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 29 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 30 document are to be interpreted as described in RFC 2119 [RFC2119]. 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 September 15, 2011. 49 Copyright Notice 51 Copyright (c) 2011 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 . . . . . . . . . . . . . . . . . . . . . . . . . 3 67 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 68 3. UMH Selection based on tunnel status . . . . . . . . . . . . . 3 69 3.1. Determining the status of a tunnel . . . . . . . . . . . . 4 70 3.1.1. mVPN tunnel root tracking . . . . . . . . . . . . . . 5 71 3.1.2. PE-P Upstream link status . . . . . . . . . . . . . . 5 72 3.1.3. P2MP RSVP-TE tunnels . . . . . . . . . . . . . . . . . 5 73 3.1.4. Leaf-initiated P-tunnels . . . . . . . . . . . . . . . 6 74 3.1.5. P2MP LSP OAM . . . . . . . . . . . . . . . . . . . . . 6 75 3.1.6. (S,G) counter information . . . . . . . . . . . . . . 6 76 4. Standby C-multicast route . . . . . . . . . . . . . . . . . . 7 77 4.1. Downstream PE behavior . . . . . . . . . . . . . . . . . . 7 78 4.2. Upstream PE behavior . . . . . . . . . . . . . . . . . . . 8 79 4.3. Reachability determination . . . . . . . . . . . . . . . . 9 80 4.4. Inter-AS . . . . . . . . . . . . . . . . . . . . . . . . . 10 81 4.4.1. Inter-AS procedures for downstream PEs, ASBR fast 82 failover . . . . . . . . . . . . . . . . . . . . . . . 10 83 4.4.2. Inter-AS procedures for ASBRs . . . . . . . . . . . . 10 84 5. Hot leaf standby . . . . . . . . . . . . . . . . . . . . . . . 11 85 6. Duplicate packets . . . . . . . . . . . . . . . . . . . . . . 12 86 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 87 8. Security Considerations . . . . . . . . . . . . . . . . . . . 12 88 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12 89 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 90 10.1. Normative References . . . . . . . . . . . . . . . . . . . 12 91 10.2. Informative References . . . . . . . . . . . . . . . . . . 13 92 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13 94 1. Introduction 96 In the context of multicast in BGP/MPLS VPNs, it is desirable to 97 provide mechanisms allowing fast recovery of connectivity on 98 different types of failures. This document addresses failures of 99 elements in the provider network that are upstream of PEs connected 100 to VPN sites with receivers. 102 The sections 3 and 4 describe two independent mechanisms, allowing 103 different levels of resiliency, and providing different failure 104 coverage: 106 o Section 3 describes local procedures allowing an egress PE (a PE 107 connected to a receiver site) to take into account the status of 108 P-Tunnels to determine the Upstream Multicast Hop (UMH) for a 109 given (C-S, C-G). 111 o Section 4 describes protocol extensions that can speed up failover 112 by not requiring any multicast VPN routing message exchange at 113 recovery time. 115 Moreover, section 5 describes a "hot leaf standby" mechanism, that 116 uses a combination of these two mechanisms. This approach has 117 similarities with the solution described in [I-D.karan-mofrr] to 118 improve failover times when PIM routing is used in a network given 119 some topology and metric constraints. 121 2. Terminology 123 The terminology used in this document is the terminology defined in 124 [I-D.ietf-l3vpn-2547bis-mcast] and 125 [I-D.ietf-l3vpn-2547bis-mcast-bgp]. 127 3. UMH Selection based on tunnel status 129 Current multicast VPN specifications [I-D.ietf-l3vpn-2547bis-mcast], 130 section 5.1, describe the procedures used by a multicast VPN 131 downstream PE to determine what the upstream multicast hop (UMH) is 132 for a said (C-S,C-G). 134 The procedure described here is an OPTIONAL procedure that consist in 135 having a downstream PE take into account the status of P-tunnels 136 rooted at each possible upstream PEs, for including or not including 137 each said PE in the list of candidate UMHs for a said (C-S,C-G) 138 state. The result is that, if a P-tunnel is "down" (see 139 Section 3.1), the PE that is the root of the P-Tunnel will not be 140 considered for UMH selection, which will result in the downstream PE 141 to failover to the upstream PE which is next in the list of 142 candidates. 144 More precisely, UMH determination for a said (C-S,C-G) will consider 145 the UMH candidates in the following order: 147 o first, the UMH candidates that either (a) advertise a PMSI bound 148 to a tunnel that is "up", or (b) do not advertise any I- or S- 149 PMSI applicable to the said (C-S,C-G) but have associated a VRF 150 Route Import BGP attribute to the unicast VPN route for S (this is 151 necessary to avoid considering invalid some UMH PEs that use a 152 policy where no I-PMSI is advertized for a said VRF and where only 153 S-PMSI are used, the S-PMSI advertisement being possibly done only 154 after the upstream PE receives a C-multicast route for (C-S, 155 C-G)/(C-*, C-G) to be carried over the advertized S-PMSI) 157 o second, the UMH candidates that advertise a PMSI bound to a tunnel 158 that is "down" -- these will thus be used as a last resort to 159 ensure a graceful fallback to the basic MVPN UMH selection 160 procedures in the hypothetical case where a false negative would 161 occur when determining the status of all tunnels 163 For a said downstream PE and a said VRF, the P-tunnel corresponding 164 to a said upstream PE for a said (C-S,C-G) state is the S-PMSI tunnel 165 advertized by that upstream PE for this (C-S,C-G) and imported into 166 that VRF, or if there isn't any such S-PMSI, the I-PMSI tunnel 167 advertized by that PE and imported into that VRF. 169 Note that this documents assumes that if a site of a given MVPN that 170 contains C-S is dual-homed to two PEs, then all the other sites of 171 that MVPN would have two unicast VPN routes (VPN-IPv4 or VPN-IPv6) 172 routes to C-S, each with its own RD. 174 3.1. Determining the status of a tunnel 176 Different factors can be considered to determine the "status" of a 177 P-tunnel and are described in the following sub-sections. The 178 procedure proposed here also allows that all downstream PEs don't 179 apply the same rules to define what the status of a P-tunnel is 180 (please see Section 6), and some of them will produce a result that 181 may be different for different downstream PEs. Thus what is called 182 the "status" of a P-tunnel in this section, is not a characteristic 183 of the tunnel in itself, but is the status of the tunnel, *as seen 184 from a particular downstream PE*. 186 Depending on the criteria used to determine the status of a P-tunnel, 187 there may be an interaction with other resiliency mechanism used for 188 the P-tunnel itself, and the UMH update may happen immediately or may 189 need to be delayed. Each particular case is covered in each separate 190 sub-section below. 192 3.1.1. mVPN tunnel root tracking 194 A condition to consider that the status of a P-tunnel is up is that 195 the root of the tunnel, as determined in the PMSI tunnel attribute, 196 is reachable through unicast routing tables. In this case the 197 downstream PE can immediately update its UMH when the reachability 198 condition changes. 200 This is similar to BGP next-hop tracking for VPN routes, except that 201 the address considered is not the BGP next-hop address, but the root 202 address in the PMSI tunnel attribute. 204 If BGP next-hop tracking is done for VPN routes, and the root address 205 of a said tunnel happens to be the same as the next-hop address in 206 the BGP autodiscovery route advertising the tunnel, then this 207 mechanisms may be omitted for this tunnel, as it will not bring any 208 specific benefit. 210 3.1.2. PE-P Upstream link status 212 A condition to consider a tunnel status as up can be that the last- 213 hop link of the P-tunnel is up. 215 In that case, if the PE can determine that there is no fast 216 restoration mechanism (such as MPLS FRR [RFC4090]) in place for the 217 P-tunnel, it can update the UMH immediately. Else, it should wait 218 before updating the UMH, to let the P-tunnel restoration mechanism 219 happen. A configurable timer MUST be provided for this purpose, and 220 it is recommended to provide a reasonable default value for this 221 timer. 223 3.1.3. P2MP RSVP-TE tunnels 225 For P-Tunnels of type P2MP MPLS-TE, the status of the P-Tunnel is 226 considered up if one or more of the P2MP RSVP-TE LSPs, identified by 227 the P-Tunnel Attribute, are in up state. The determination of 228 whether a P2MP RSVP-TE LSP is in up state requires Path and Resv 229 state for the LSP and is based on procedures in [RFC4875]. In this 230 case the downstream PE can immediately update its UMH when the 231 reachability condition changes. 233 When signaling state for a P2MP TE LSP is removed (e.g. if the 234 ingress of the P2MP TE LSP sends a PathTear message) or the P2MP TE 235 LSP changes state from up to down as determined by procedures in 237 [RFC4875], the status of the corresponding P-Tunnel SHOULD be re- 238 evaluated. If the P-Tunnel transitions from up to down state, the 239 upstream PE, that is the ingress of the P-Tunnel, SHOULD not be 240 considered a valid UMH. 242 3.1.4. Leaf-initiated P-tunnels 244 A PE can be removed from the UMH candidate list for a said (S,G) if 245 the P-tunnel for this S,G (I or S , depending) is leaf triggered 246 (PIM, mLDP), but for some reason internal to the protocol the 247 upstream one-hop branch of the tunnel from P to PE cannot be built. 248 In this case the downstream PE can immediately update its UMH when 249 the reachability condition changes. 251 3.1.5. P2MP LSP OAM 253 When a P2MP connectivity verification mechanism such as 254 [I-D.katz-ward-bfd-multipoint] used in conjunction with bootstrapping 255 mechanisms described in [I-D.ietf-mpls-mcast-cv] has been setup for a 256 tunnel, the result of the connectivity verification can be used to 257 define the status of the tree. 259 If a MultipointHead session has been established on a P2MP MPLS LSP 260 so that BFD packets are periodically sent from the root toward 261 leaves, a condition to consider the status of corresponding tunnel as 262 up is that the BFD SessionState is Up. 264 When such a procedure is used, in context where fast restoration 265 mechanisms are used for the P-tunnels, downstream PEs should be 266 configured to wait before updating the UMH, to let the P-tunnel 267 restoration mechanism happen. A configurable timer MUST be provided 268 for this purpose, and it is recommended to provide a reasonable 269 default value for this timer. 271 3.1.6. (S,G) counter information 273 In cases, where the downstream node can be configured so that the 274 maximum inter-packet time is known for all the multicast flows mapped 275 on a P-tunnel, the local per-(C-S,C-G) traffic counter information 276 for traffic received on this P-tunnel can be used to determine the 277 status of the P-tunnel. 279 When such a procedure is used, in context where fast restoration 280 mechanisms are used for the P-tunnels, downstream PEs should be 281 configured to wait before updating the UMH, to let the P-tunnel 282 restoration mechanism happen. A configurable timer MUST be provided 283 for this purpose, and it is recommended to provide a reasonable 284 default value for this timer. 286 This method can be applicable for instance when a (S,G) flow is 287 mapped on an S-PMSI. 289 In cases where this mechanism is used in conjunction with Hot leaf 290 standby, then no prior knowledge of the rate of the multicast streams 291 is required ; downstream PEs can compare reception on the two 292 P-tunnels to determine when one of them is down. 294 4. Standby C-multicast route 296 The procedures described below are limited to the case where the site 297 that contains C-S is connected to exactly two PEs. The procedures 298 require all the PEs of that MVPN to follow the single forwarder PE 299 selection, as specified in [I-D.ietf-l3vpn-2547bis-mcast]. The 300 procedures assume that if a site of a given MVPN that contains C-S is 301 dual-homed to two PEs, then all the other sites of that MVPN would 302 have two unicast VPN routes (VPN-IPv4 or VPN-IPv6) routes to C-S, 303 each with its own RD. 305 As long as C-S is reachable via both PEs, a said downstream PE will 306 select one of the PEs connected to C-S as its Upstream PE with 307 respect to C-S. We will refer to the other PE connected to C-S as 308 the "Standby Upstream PE". Note that if the connectivity to C-S 309 through the Primary Upstream PE becomes unavailable, then the PE will 310 select the Standby Upstream PE as its Upstream PE with respect to 311 C-S. 313 For readability, in the following sub-sections, the procedures are 314 described for BGP C-multicast Source Tree Join routes, but they apply 315 equally to BGP C-multicast Shared Tree Join routes failover for the 316 case where the customer RP is dual-homed (substitute "C-RP" to 317 "C-S"). 319 4.1. Downstream PE behavior 321 When a (downstream) PE connected to some site of an MVPN needs to 322 send a C-multicast route (C-S, C-G), then following the procedures 323 specified in Section "Originating C-multicast routes by a PE" of 324 [I-D.ietf-l3vpn-2547bis-mcast-bgp] the PE sends the C-multicast route 325 with RT that identifies the Upstream PE selected by the PE 326 originating the route. As long as C-S is reachable via the Primary 327 Upstream PE, the Upstream PE is the Primary Upstream PE. If C-S is 328 reachable only via the Standby Upstream PE, then the Upstream PE is 329 the Standby Upstream PE. 331 If C-S is reachable via both the Primary and the Standby Upstream PE, 332 then in addition to sending the C-multicast route with an RT that 333 identifies the Primary Upstream PE, the PE also originates and sends 334 a C-multicast route with an RT that identifies the Standby Upstream 335 PE. This route, that has the semantic of being a 'standby' 336 C-multicast route, is further called a "Standby BGP C-multicast 337 route", and is constructed as follows: 339 o the NLRI is constructed as the original C-multicast route, except 340 that the RD is the same as if the C-multicast route was built 341 using the standby PE as the UMH (it will carry the RD associated 342 to the unicast VPN route advertized by the standby PE for S) 344 o MUST carry the "Standby PE" BGP Community (this is a new BGP 345 Community, see Section 7) 347 The normal and the standby C-multicast routes must have their Local 348 Preference attribute adjusted so that, if two C-multicast routes with 349 same NLRI are received by a BGP peer, one carrying the "Standby PE" 350 attribute and the other one *not* carrying the "Standby PE" 351 community, then preference is given to the one *not* carrying the 352 "Standby PE" attribute. Such a situation can happen when, for 353 instance due to transient unicast routing inconsistencies, two 354 different downstream PEs consider different upstream PEs to be the 355 primary one ; in that case, without any precaution taken, both 356 upstream PEs would process a standby C-multicast route and possibly 357 stop forwarding at the same time. For this purpose a Standby BGP 358 C-multicast route MUST have the LOCAL_PREF attribute set to zero. 360 Note that, when a PE advertizes such a Standby C-multicast join for 361 an (S,G) it must join the corresponding P-tunnel. 363 If at some later point the local PE determines that C-S is no longer 364 reachable through the Primary Upstream PE, the Standby Upstream PE 365 becomes the Upstream PE, and the local PE re-sends the C-multicast 366 route with RT that identifies the Standby Upstream PE, except that 367 now the route does not carry the Standby PE BGP Community (which 368 results in replacing the old route with a new route, with the only 369 difference between these routes being the presence/absence of the 370 Standby PE BGP Community). 372 4.2. Upstream PE behavior 374 When a PE receives a C-multicast route for a particular (C-S, C-G), 375 and the RT carried in the route results in importing the route into a 376 particular VRF on the PE, if the route carries the Standby PE BGP 377 Community, then the PE performs as follows: 379 when the PE determines that C-S is not reachable through some 380 other PE, the PE SHOULD install VRF PIM state corresponding to 381 this Standby BGP C-multicast route (the result will be that a PIM 382 Join message will be sent to the CE towards C-S, and that the PE 383 will receive (C-S,C-G) traffic), and the PE SHOULD forward (C-S, 384 C-G) traffic received by the PE to other PEs through a P-tunnel 385 rooted at the PE. 387 Furthermore, irrespective of whether C-S carried in that route is 388 reachable through some other PE: 390 a) based on local policy, as soon as the PE receives this Standby BGP 391 C-multicast route, the PE MAY install VRF PIM state corresponding 392 to this BGP Source Tree Join route (the result will be that Join 393 messages will be sent to the CE toward C-S, and that the PE will 394 receive (C-S,C-G) traffic) 396 b) based on local policy, as soon as the PE receives this Standby BGP 397 C-multicast route, the PE MAY forward (C-S, C-G) traffic to other 398 PEs through a P-tunnel independently of the reachability of C-S 399 through some other PE. [note that this implies also doing (a)] 401 Doing neither (a), nor (b) for a said (C-S,C-G) is called "cold root 402 standby". 404 Doing (a) but not (b) for a said (C-S,C-G) is called "warm root 405 standby". 407 Doing (b) (which implies also doing (a)) for a said (C-S,C-G) is 408 called "hot root standby". 410 Note that, if an upstream PE uses an S-PMSI only policy, it shall 411 advertise an S-PMSI for an (S,G) as soon as it receives a C-multicast 412 route for (S,G), normal or Standby ; i.e. it shall not wait for 413 receiving a non-Standby C-multicast route before advertising the 414 corresponding S-PMSI. 416 4.3. Reachability determination 418 The standby PE can use the following information to determine that 419 C-S can or cannot be reached through the primary PE: 421 o presence/absence of a unicast VPN route toward C-S 423 o supposing that the standby PE is an egress of the tunnel rooted at 424 the Primary PE, the standby PE can determine the reachability of 425 C-S through the Primary PE based on the status of this tunnel, 426 determined thanks to the same criteria as the ones described in 427 Section 3.1 (without using the UMH selection procedures of 428 Section 3) 430 o other mechanisms MAY be used 432 4.4. Inter-AS 434 If the non-segmented inter-AS approach is used, the procedures in 435 section 4 can be applied. 437 When multicast VPNs are used in a inter-AS context with the segmented 438 inter-AS approach described in section 8.2 of 439 [I-D.ietf-l3vpn-2547bis-mcast-bgp], the procedures in this section 440 can be applied. 442 A pre-requisite for the procedures described below to be applied for 443 a source of a said MVPN is: 445 o that any PE of this MVPN receives two Inter-AS I-PMSI auto- 446 discovery routes advertized by the AS of the source (or more) 448 o that these Inter-AS I-PMSI autodiscovery routes have distinct 449 Route Distinguishers (as described in item "(2)" of section 9.2 of 450 [I-D.ietf-l3vpn-2547bis-mcast-bgp]). 452 As an example, these conditions will be satisfied when the source is 453 dual homed to an AS that connects to the receiver AS through two ASBR 454 using auto-configured RDs. 456 4.4.1. Inter-AS procedures for downstream PEs, ASBR fast failover 458 The following procedure is applied by downstream PEs of an AS, for a 459 source S in a remote AS. 461 Additionally to choosing an Inter-AS I-PMSI autodiscovery route 462 advertized from the AS of the source to construct a C-multicast 463 route, as described in section 11.1.3 464 [I-D.ietf-l3vpn-2547bis-mcast-bgp] a downstream PE will choose a 465 second Inter-AS I-PMSI autodiscovery route advertized from the AS of 466 the source and use this route to construct and advertise a Standby 467 C-multicast route (C-multicast route carrying the Standby extended 468 community) as described in Section 4.1. 470 4.4.2. Inter-AS procedures for ASBRs 472 When an upstream ASBR receives a C-multicast route, and at least one 473 of the RTs of the route matches one of the ASBR Import RT, the ASBR 474 locates an Inter-AS I-PMSI A-D route whose RD and Source AS matches 475 the RD and Source AS carried in the C-multicast route. If the match 476 is found, and C-multicast route carries the Standby PE BGP Community, 477 then the ASBR performs as follows: 479 o if the route was received over iBGP ; the route is expected to 480 have a LOCAL_PREF attribute set to zero and it should be re- 481 advertized in eBGP with a MED attribute (MULTI_EXIT_DISC) set to 482 the highest possible value (0xffff) 484 o if the route was received over eBGP ; the route is expected to 485 have a MED attribute set of 0xffff and should be re-advertized in 486 iBGP with a LOCAL_PREF attribute set to zero 488 Other ASBR procedures are applied without modification. 490 5. Hot leaf standby 492 The mechanisms defined in sections Section 4 and Section 3 can be 493 used together as follows. 495 The principle is that, for a said VRF (or possibly only for a said 496 C-S,C-G): 498 o downstream PEs advertise a Standby BGP C-multicast route (based on 499 Section 4) 501 o upstream PEs use the "hot standby" optional behavior and thus will 502 forward traffic for a said multicast state as soon as they have 503 whether a (primary) BGP C-multicast route or a Standby BGP 504 C-multicast route for that state (or both) 506 o downstream PEs accept traffic from the primary or standby tunnel, 507 based on the status of the tunnel (based on Section 3) 509 Other combinations of the mechanisms proposed in Section 4) and 510 Section 3 are for further study. 512 Note that the same level of protection would be achievable with a 513 simple C-multicast Source Tree Join route advertized to both the 514 primary and secondary upstream PEs (carrying as Route Target extended 515 communities, the values of the VRF Route Import attribute of each VPN 516 route from each upstream PEs). The advantage of using the Standby 517 semantic for is that, supposing that downstream PEs always advertise 518 a Standby C-multicast route to the secondary upstream PE, it allows 519 to choose the protection level through a change of configuration on 520 the secondary upstream PE, without requiring any reconfiguration of 521 all the downstream PEs. 523 6. Duplicate packets 525 Multicast VPN specifications [I-D.ietf-l3vpn-2547bis-mcast] impose 526 that a PE only forwards to CEs the packets coming from the expected 527 usptream PE (Section 9.1). 529 We highlight the reader's attention to the fact that the respect of 530 this part of multicast VPN specifications is especially important 531 when two distinct upstream PEs are susceptible to forward the same 532 traffic on P-tunnels at the same time in steady state. This will be 533 the case when "hot root standby" mode is used (Section 4), and which 534 can also be the case if procedures of Section 3 are used and (a) the 535 rules determining the status of a tree are not the same on two 536 distinct downstream PEs or (b) the rule determining the status of a 537 tree depend on conditions local to a PE (e.g. the PE-P upstream link 538 being up). 540 7. IANA Considerations 542 Allocation is expected from IANA for the BGP "Standby PE" community. 543 (TBC) 545 [Note to RFC Editor: this section may be removed on publication as an 546 RFC.] 548 8. Security Considerations 550 9. Acknowledgements 552 The authors want to thank Greg Reaume for its review and useful 553 feedback. 555 10. References 557 10.1. Normative References 559 [I-D.ietf-l3vpn-2547bis-mcast] 560 Aggarwal, R., Bandi, S., Cai, Y., Morin, T., Rekhter, Y., 561 Rosen, E., Wijnands, I., and S. Yasukawa, "Multicast in 562 MPLS/BGP IP VPNs", draft-ietf-l3vpn-2547bis-mcast-10 (work 563 in progress), January 2010. 565 [I-D.ietf-l3vpn-2547bis-mcast-bgp] 566 Aggarwal, R., Rosen, E., Morin, T., and Y. Rekhter, "BGP 567 Encodings and Procedures for Multicast in MPLS/BGP IP 568 VPNs", draft-ietf-l3vpn-2547bis-mcast-bgp-08 (work in 569 progress), September 2009. 571 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 572 Requirement Levels", BCP 14, RFC 2119, March 1997. 574 [RFC4875] Aggarwal, R., Papadimitriou, D., and S. Yasukawa, 575 "Extensions to Resource Reservation Protocol - Traffic 576 Engineering (RSVP-TE) for Point-to-Multipoint TE Label 577 Switched Paths (LSPs)", RFC 4875, May 2007. 579 10.2. Informative References 581 [I-D.ietf-mpls-mcast-cv] 582 Swallow, G., "Connectivity Verification for Multicast 583 Label Switched Paths", draft-ietf-mpls-mcast-cv-00 (work 584 in progress), April 2007. 586 [I-D.karan-mofrr] 587 Karan, A., Filsfils, C., Farinacci, D., Decraene, B., 588 Leymann, N., and T. Telkamp, "Multicast only Fast Re- 589 Route", draft-karan-mofrr-01 (work in progress), 590 March 2011. 592 [I-D.katz-ward-bfd-multipoint] 593 Katz, D. and D. Ward, "BFD for Multipoint Networks", 594 draft-katz-ward-bfd-multipoint-02 (work in progress), 595 February 2009. 597 [RFC4090] Pan, P., Swallow, G., and A. Atlas, "Fast Reroute 598 Extensions to RSVP-TE for LSP Tunnels", RFC 4090, 599 May 2005. 601 Authors' Addresses 603 Thomas Morin 604 France Telecom - Orange Labs 605 2, avenue Pierre Marzin 606 Lannion 22307 607 France 609 Email: thomas.morin@orange-ftgroup.com 610 Yakov Rekhter 611 Juniper Networks 612 1194 North Mathilda Ave. 613 Sunnyvale, CA 94089 614 U.S.A. 616 Email: yakov@juniper.net 618 Rahul Aggarwal 619 Juniper Networks 620 1194 North Mathilda Ave. 621 Sunnyvale, CA 94089 622 U.S.A. 624 Email: rahul@juniper.net 626 Wim Henderickx 627 Alcatel-Lucent 628 Copernicuslaan 50 629 Antwerp 2018 630 Belgium 632 Email: wim.henderickx@alcatel-lucent.com 634 Praveen Muley 635 Alcatel-Lucent 636 701 East Middlefield Rd 637 Mountain View, CA 94043 638 U.S.A. 640 Email: praveen.muley@alcatel-lucent.com 642 Ray (Lei) Qiu 643 Huawei 644 2330 Central Expressway 645 Santa Clara, CA 95050 646 U.S.A. 648 Email: rayq@huawei.com