idnits 2.17.1 draft-morin-l3vpn-mvpn-fast-failover-03.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- ** The document seems to lack a License Notice according IETF Trust Provisions of 28 Dec 2009, Section 6.b.ii or Provisions of 12 Sep 2009 Section 6.b -- however, there's a paragraph with a matching beginning. Boilerplate error? (You're using the IETF Trust Provisions' Section 6.b License Notice from 12 Feb 2009 rather than one of the newer Notices. See https://trustee.ietf.org/license-info/.) 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 (October 26, 2009) is 5296 days in the past. Is this intentional? Checking references for intended status: Experimental ---------------------------------------------------------------------------- == Outdated reference: A later version (-10) exists of draft-ietf-l3vpn-2547bis-mcast-08 == Outdated reference: A later version (-02) exists of draft-karan-mofrr-00 Summary: 1 error (**), 0 flaws (~~), 4 warnings (==), 2 comments (--).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: April 29, 2010 R. Aggarwal 6 Juniper Networks 7 W. Henderickx 8 P. Muley 9 Q. Ray 10 Alcatel-Lucent 11 October 26, 2009 13 Multicast VPN fast upstream failover 14 draft-morin-l3vpn-mvpn-fast-failover-03 16 Status of this Memo 18 This Internet-Draft is submitted to IETF in full conformance with the 19 provisions of BCP 78 and BCP 79. 21 Internet-Drafts are working documents of the Internet Engineering 22 Task Force (IETF), its areas, and its working groups. Note that 23 other groups may also distribute working documents as Internet- 24 Drafts. 26 Internet-Drafts are draft documents valid for a maximum of six months 27 and may be updated, replaced, or obsoleted by other documents at any 28 time. It is inappropriate to use Internet-Drafts as reference 29 material or to cite them other than as "work in progress." 31 The list of current Internet-Drafts can be accessed at 32 http://www.ietf.org/ietf/1id-abstracts.txt. 34 The list of Internet-Draft Shadow Directories can be accessed at 35 http://www.ietf.org/shadow.html. 37 This Internet-Draft will expire on April 29, 2010. 39 Copyright Notice 41 Copyright (c) 2009 IETF Trust and the persons identified as the 42 document authors. All rights reserved. 44 This document is subject to BCP 78 and the IETF Trust's Legal 45 Provisions Relating to IETF Documents in effect on the date of 46 publication of this document (http://trustee.ietf.org/license-info). 47 Please review these documents carefully, as they describe your rights 48 and restrictions with respect to this document. 50 Abstract 52 This document defines multicast VPN extensions and procedures that 53 allow fast failover for upstream failures, by allowing downstream PEs 54 to take into account the status of Provider-Tunnels (P-tunnels) when 55 selecting the upstream PE for a VPN multicast flow, and extending BGP 56 MVPN routing so that a C-multicast route can be advertised toward a 57 standby upstream PE. 59 Requirements Language 61 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 62 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 63 document are to be interpreted as described in RFC 2119 [RFC2119]. 65 Table of Contents 67 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 68 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 69 3. UMH Selection based on tunnel status . . . . . . . . . . . . . 3 70 3.1. Determining the status of a tunnel . . . . . . . . . . . . 4 71 3.1.1. mVPN tunnel root tracking . . . . . . . . . . . . . . 5 72 3.1.2. PE-P Upstream link status . . . . . . . . . . . . . . 5 73 3.1.3. P2MP RSVP-TE tunnels . . . . . . . . . . . . . . . . . 5 74 3.1.4. Leaf-initiated P-tunnels . . . . . . . . . . . . . . . 6 75 3.1.5. P2MP LSP OAM . . . . . . . . . . . . . . . . . . . . . 6 76 3.1.6. (S,G) counter information . . . . . . . . . . . . . . 6 77 4. Standby C-multicast route . . . . . . . . . . . . . . . . . . 7 78 4.1. Downstream PE behavior . . . . . . . . . . . . . . . . . . 7 79 4.2. Upstream PE behavior . . . . . . . . . . . . . . . . . . . 8 80 4.3. Reachability determination . . . . . . . . . . . . . . . . 9 81 4.4. Inter-AS . . . . . . . . . . . . . . . . . . . . . . . . . 10 82 4.4.1. Inter-AS procedures for downstream PEs, ASBR fast 83 failover . . . . . . . . . . . . . . . . . . . . . . . 10 84 4.4.2. Inter-AS procedures for ASBRs . . . . . . . . . . . . 10 85 5. Hot leaf standby . . . . . . . . . . . . . . . . . . . . . . . 11 86 6. Duplicate packets . . . . . . . . . . . . . . . . . . . . . . 12 87 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 88 8. Security Considerations . . . . . . . . . . . . . . . . . . . 12 89 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12 90 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 91 10.1. Normative References . . . . . . . . . . . . . . . . . . . 12 92 10.2. Informative References . . . . . . . . . . . . . . . . . . 13 93 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13 95 1. Introduction 97 In the context of multicast in BGP/MPLS VPNs, it is desirable to 98 provide mechanisms allowing fast recovery of connectivity on 99 different types of failures. This document addresses failures of 100 elements in the provider network that are upstream of PEs connected 101 to VPN sites with receivers. 103 The sections 3 and 4 describe two independent mechanisms, allowing 104 different levels of resiliency, and providing different failure 105 coverage: 107 o Section 3 describes local procedures allowing an egress PE (a PE 108 connected to a receiver site) to take into account the status of 109 P-Tunnels to determine the Upstream Multicast Hop (UMH) for a 110 given (C-S, C-G). 112 o Section 4 describes protocol extensions that can speed up failover 113 by not requiring any multicast VPN routing message exchange at 114 recovery time. 116 Moreover, section 5 describes a "hot leaf standby" mechanism, that 117 uses a combination of these two mechanisms. This approach has 118 similarities with the solution described in [I-D.karan-mofrr] to 119 improve failover times when PIM routing is used in a network given 120 some topology and metric constraints. 122 2. Terminology 124 The terminology used in this document is the terminology defined in 125 [I-D.ietf-l3vpn-2547bis-mcast] and 126 [I-D.ietf-l3vpn-2547bis-mcast-bgp]. 128 3. UMH Selection based on tunnel status 130 Current multicast VPN specifications [I-D.ietf-l3vpn-2547bis-mcast], 131 section 5.1, describe the procedures used by a multicast VPN 132 downstream PE to determine what the upstream multicast hop (UMH) is 133 for a said (C-S,C-G). 135 The procedure described here is an OPTIONAL procedure that consist in 136 having a downstream PE take into account the status of P-tunnels 137 rooted at each possible upstream PEs, for including or not including 138 each said PE in the list of candidate UMHs for a said (C-S,C-G) 139 state. The result is that, if a P-tunnel is "down" (see 140 Section 3.1), the PE that is the root of the P-Tunnel will not be 141 considered for UMH selection, which will result in the downstream PE 142 to failover to the upstream PE which is next in the list of 143 candidates. 145 More precisely, UMH determination for a said (C-S,C-G) will consider 146 the UMH candidates in the following order: 148 o first, the UMH candidates that either (a) advertise a PMSI bound 149 to a tunnel that is "up", or (b) do not advertise any I- or S- 150 PMSI applicable to the said (C-S,C-G) but have associated a VRF 151 Route Import BGP attribute to the unicast VPN route for S (this is 152 necessary to avoid considering invalid some UMH PEs that use a a 153 policy where no I-PMSI is advertized for a said VRF and where only 154 S-PMSI are used, the S-PMSI advertisement being possibly done only 155 after the upstream PE receives a C-multicast route for (C-S, 156 C-G)/(C-*, C-G) to be carried over the advertised S-PMSI) 158 o second, the UMH candidates that advertise a PMSI bound to a tunnel 159 that is "down" -- these will thus be used as a last resort to 160 ensure a graceful fallback to the basic MVPN UMH selection 161 procedures in the hypothetical case where a false negative would 162 occur when determining the status of all tunnels 164 For a said downstream PE and a said VRF, the P-tunnel corresponding 165 to a said upstream PE for a said (C-S,C-G) state is the S-PMSI tunnel 166 advertized by that upstream PE for this (C-S,C-G) and imported into 167 that VRF, or if there isn't any such S-PMSI, the I-PMSI tunnel 168 advertized by that PE and imported into that VRF. 170 Note that this documents assumes that if a site of a given MVPN that 171 contains C-S is dual-homed to two PEs, then all the other sites of 172 that MVPN would have two unicast VPN routes (VPN-IPv4 or VPN-IPv6) 173 routes to C-S, each with its own RD. 175 3.1. Determining the status of a tunnel 177 Different factors can be considered to determine the "status" of a 178 P-tunnel and are described in the following sub-sections. The 179 procedure proposed here also allows that all downstream PEs don't 180 apply the same rules to define what the status of a P-tunnel is 181 (please see Section 6), and some of them will produce a result that 182 may be different for different downstream PEs. Thus what is called 183 the "status" of a P-tunnel in this section, is not a characteristic 184 of the tunnel in itself, but is the status of the tunnel, *as seen 185 from a particular downstream PE*. 187 Depending on the criteria used to determine the status of a P-tunnel, 188 there may be an interaction with other resiliency mechanism used for 189 the P-tunnel itself, and the UMH update may happen immediately or may 190 need to be delayed. Each particular case is covered in each separate 191 sub-section below. 193 3.1.1. mVPN tunnel root tracking 195 A condition to consider that the status of a P-tunnel is up is that 196 the root of the tunnel, as determined in the PMSI tunnel attribute, 197 is reachable through unicast routing tables. In this case the 198 downstream PE can immediately update its UMH when the reachability 199 condition changes. 201 This is similar to BGP next-hop tracking for VPN routes, except that 202 the address considered is not the BGP next-hop address, but the root 203 address in the PMSI tunnel attribute. 205 If BGP next-hop tracking is done for VPN routes, and the root address 206 of a said tunnel happens to be the same as the next-hop address in 207 the BGP autodiscovery route advertising the tunnel, then this 208 mechanisms may be omitted for this tunnel, as it will not bring any 209 specific benefit. 211 3.1.2. PE-P Upstream link status 213 A condition to consider a tunnel status as up can be that the last- 214 hop link of the P-tunnel is up. 216 In that case, if the PE can determine that there is no fast 217 restoration mechanism (such as MPLS FRR [RFC4090]) in place for the 218 P-tunnel, it can update the UMH immediately. Else, it should wait 219 before updating the UMH, to let the P-tunnel restoration mechanims 220 happen. A configurable timer MUST be provided for this purpose, and 221 it is recommended to provide a reasonable default value for this 222 timer. 224 3.1.3. P2MP RSVP-TE tunnels 226 For P-Tunnels of type P2MP MPLS-TE, the status of the P-Tunnel is 227 considered up if one or more of the P2MP RSVP-TE LSPs, identified by 228 the P-Tunnel Attribute, are in up state. The determination of 229 whether a P2MP RSVP-TE LSP is in up state requires Path and Resv 230 state for the LSP and is based on procedures in [RFC4875]. In this 231 case the downstream PE can immediately update its UMH when the 232 reachability condition changes. 234 When signaling state for a P2MP TE LSP is removed (e.g. if the 235 ingress of the P2MP TE LSP sends a PathTear message) or the P2MP TE 236 LSP changes state from up to down as determined by procedures in 238 [RFC4875], the status of the corresponding P-Tunnel SHOULD be re- 239 evaluated. If the P-Tunnel transitions from up to down state, the 240 upstream PE, that is the ingress of the P-Tunnel, SHOULD not be 241 considered a valid UMH. 243 3.1.4. Leaf-initiated P-tunnels 245 A PE can be removed from the UMH candidate list for a said (S,G) if 246 the P-tunnel for this S,G (I or S , depending) is leaf triggered 247 (PIM, mLDP), but for some reason internal to the protocol the 248 upstream one-hop branch of the tunnel from P to PE cannot be built. 249 In this case the downstream PE can immediately update its UMH when 250 the reachability condition changes. 252 3.1.5. P2MP LSP OAM 254 When a P2MP connectivity verification mechanism such as 255 [I-D.katz-ward-bfd-multipoint] used in conjunction with bootstraping 256 mechanisms described in [I-D.ietf-mpls-mcast-cv] has been setup for a 257 tunnel, the result of the connectivity verification can be used to 258 define the status of the tree. 260 If a MultipointHead session has been established on a P2MP MPLS LSP 261 so that BFD packets are periodically sent from the root toward 262 leaves, a condition to consider the status of corresponding tunnel as 263 up is that the BFD SessionState is Up. 265 When such a procedure is used, in context where fast restoration 266 mechanisms are used for the P-tunnels, downstream PEs should be 267 configured to wait before updating the UMH, to let the P-tunnel 268 restoration mechanims happen. A configurable timer MUST be provided 269 for this purpose, and it is recommended to provide a reasonable 270 default value for this timer. 272 3.1.6. (S,G) counter information 274 In cases, where the downstream node can be configured so that the 275 maximum inter-packet time is known for all the multicast flows mapped 276 on a P-tunnel, the local per-(C-S,C-G) traffic counter information 277 for traffic received on this P-tunnel can be used to determine the 278 status of the P-tunnel. 280 When such a procedure is used, in context where fast restoration 281 mechanisms are used for the P-tunnels, downstream PEs should be 282 configured to wait before updating the UMH, to let the P-tunnel 283 restoration mechanims happen. A configurable timer MUST be provided 284 for this purpose, and it is recommended to provide a reasonable 285 default value for this timer. 287 This method can be applicable for instance when a (S,G) flow is 288 mapped on an S-PMSI. 290 In cases where this mechanism is used in conjunction with Hot leaf 291 standby, then no prior knowledge of the rate of the multicast streams 292 is required ; downstream PEs can compare reception on the two 293 P-tunnels to determine when one of them is down. 295 4. Standby C-multicast route 297 The procedures described below are limited to the case where the site 298 that contains C-S is connected to exactly two PEs. The procedures 299 require all the PEs of that MVPN to follow the single forwarder PE 300 selection, as specified in [I-D.ietf-l3vpn-2547bis-mcast]. The 301 procedures assume that if a site of a given MVPN that contains C-S is 302 dual-homed to two PEs, then all the other sites of that MVPN would 303 have two unicast VPN routes (VPN-IPv4 or VPN-IPv6) routes to C-S, 304 each with its own RD. 306 As long as C-S is reachable via both PEs, a said downstream PE will 307 select one of the PEs connected to C-S as its Upstream PE with 308 respect to C-S. We will refer to the other PE connected to C-S as 309 the "Standby Upstream PE". Note that if the connectivity to C-S 310 through the Primary Upstream PE becomes unavailable, then the PE will 311 select the Standby Upstream PE as its Upstream PE with respect to 312 C-S. 314 For readability, in the following sub-sections, the procedures are 315 described for BGP C-multicast Source Tree Join routes, but they apply 316 equally to BGP C-multicast Shared Tree Join routes failover for the 317 case where the customer RP is dual-homed (substitute "C-RP" to 318 "C-S"). 320 4.1. Downstream PE behavior 322 When a (downstream) PE connected to some site of an MVPN needs to 323 send a C-multicast route (C-S, C-G), then following the procedures 324 specified in Section "Originating C-multicast routes by a PE" of 325 [I-D.ietf-l3vpn-2547bis-mcast-bgp] the PE sends the C-multicast route 326 with RT that identifies the Upstream PE selected by the PE 327 originating the route. As long as C-S is reachable via the Primary 328 Upstream PE, the Upstream PE is the Primary Upstream PE. If C-S is 329 reachable only via the Standby Upstream PE, then the Upstream PE is 330 the Standby Upstream PE. 332 If C-S is reachable via both the Primary and the Standby Upstream PE, 333 then in addition to sending the C-multicast route with an RT that 334 identifies the Primary Upstream PE, the PE also originates and sends 335 a C-multicast route with an RT that identifies the Standby Upstream 336 PE. This route, that has the semantic of being a 'standby' 337 C-multicast route, is further called a "Standby BGP C-multicast 338 route", and is constructed as follows: 340 o the NLRI is constructed as the original C-multicast route, except 341 that the RD is the same as if the C-multicast route was built 342 using the standby PE as the UMH (it will carry the RD associated 343 to the unicast VPN route advertised by the standby PE for S) 345 o MUST carry the "Standby PE" BGP Community (this is a new BGP 346 Community, see Section 7) 348 The normal and the standby C-multicast routes must have their Local 349 Preference attribute adjusted so that, if two C-multicast routes with 350 same NLRI are received by a BGP peer, one carrying the "Standby PE" 351 attribute and the other one *not* carrying the "Standby PE" 352 community, then preference is given to the one *not* carrying the 353 "Standby PE" attribute. Such a situation can happen when, for 354 instance due to transient unicast routing inconistencies, two 355 different downstream PEs consider different upstream PEs to be the 356 primary one ; in that case, without any precaution taken, both 357 upstream PEs would process a standby C-multicast route and possibly 358 stop forwarding at the same time. For this purpose a Standby BGP 359 C-multicast route MUST have the LOCAL_PREF attribute set to zero. 361 Note that, when a PE advertizes such a Standby C-multicast join for 362 an (S,G) it must join the corresponding P-tunnel. 364 If at some later point the local PE determines that C-S is no longer 365 reachable through the Primary Upstream PE, the Standby Upstream PE 366 becomes the Upstream PE, and the local PE re-sends the C-multicast 367 route with RT that identifies the Standby Upstream PE, except that 368 now the route does not carry the Standby PE BGP Community (which 369 results in replacing the old route with a new route, with the only 370 difference between these routes being the presence/absence of the 371 Standby PE BGP Community). 373 4.2. Upstream PE behavior 375 When a PE receives a C-multicast route for a particular (C-S, C-G), 376 and the RT carried in the route results in importing the route into a 377 particular VRF on the PE, if the route carries the Standby PE BGP 378 Community, then the PE performs as follows: 380 when the PE determines that C-S is not reachable through some 381 other PE, the PE SHOULD install VRF PIM state corresponding to 382 this Standby BGP C-multicast route (the result will be that a PIM 383 Join message will be sent to the CE towards C-S, and that the PE 384 will receive (C-S,C-G) traffic), and the PE SHOULD forward (C-S, 385 C-G) traffic received by the PE to other PEs through a P-tunnel 386 rooted at the PE. 388 Furthermore, irrespective of whether C-S carried in that route is 389 reachable through some other PE: 391 a) based on local policy, as soon as the PE receives this Standby BGP 392 C-multicast route, the PE MAY install VRF PIM state corresponding 393 to this BGP Source Tree Join route (the result will be that Join 394 messages will be sent to the CE toward C-S, and that the PE will 395 receive (C-S,C-G) traffic) 397 b) based on local policy, as soon as the PE receives this Standby BGP 398 C-multicast route, the PE MAY forward (C-S, C-G) traffic to other 399 PEs through a P-tunnel independently of the reachability of C-S 400 through some other PE. [note that this implies also doing (a)] 402 Doing neither (a), nor (b) for a said (C-S,C-G) is called "cold root 403 standby". 405 Doing (a) but not (b) for a said (C-S,C-G) is called "warm root 406 standby". 408 Doing (b) (which implies also doing (a)) for a said (C-S,C-G) is 409 called "hot root standby". 411 Note that, if an upstream PE uses an S-PMSI only policy, it shall 412 advertise an S-PMSI for an (S,G) as soon as it receives a C-multicast 413 route for (S,G), normal or Standby ; i.e. it shall not wait for 414 receiving a non-Standby C-multicast route before advertising the 415 corresponding S-PMSI. 417 4.3. Reachability determination 419 The standby PE can use the following information to determine that 420 C-S can or cannot be reached through the primary PE: 422 o presence/absence of a unicast VPN route toward C-S 424 o supposing that the standby PE is an egress of the tunnel rooted at 425 the Primary PE, the standby PE can determine the reachability of 426 C-S through the Primary PE based on the status of this tunnel, 427 determined thanks to the same criteria as the ones described in 428 Section 3.1 (without using the UMH selection procedures of 429 Section 3) 431 o other mechanisms MAY be used 433 4.4. Inter-AS 435 If the non-segmented inter-AS approach is used, the procedures in 436 section 4 can be applied. 438 When multicast VPNs are used in a inter-AS context with the segmented 439 inter-AS approach described in section 8.2 of 440 [I-D.ietf-l3vpn-2547bis-mcast-bgp], the procedures in this section 441 can be applied. 443 A pre-requisite for the procedures described below to be applied for 444 a source of a said MVPN is: 446 o that any PE of this MVPN receives two Inter-AS I-PMSI auto- 447 discovery routes advertized by the AS of the source (or more) 449 o that these Inter-AS I-PMSI autodiscovery routes have distinct 450 Route Distinguishers (as described in item "(2)" of section 9.2 of 451 [I-D.ietf-l3vpn-2547bis-mcast-bgp]). 453 As an example, these conditions will be satisfied when the source is 454 dual homed to an AS that connects to the receiver AS through two ASBR 455 using auto-configured RDs. 457 4.4.1. Inter-AS procedures for downstream PEs, ASBR fast failover 459 The following procedure is applied by downstream PEs of an AS, for a 460 source S in a remote AS. 462 Additionaly to choosing an Inter-AS I-PMSI autodiscovery route 463 advertized from the AS fo the source to construct a C-multicast 464 route, as described in section 11.1.3 465 [I-D.ietf-l3vpn-2547bis-mcast-bgp] a downstream PE will choose a 466 second Inter-AS I-PMSI autodiscovery route advertized from the AS fo 467 the source to advertise a Standby C-multicast route (C-multicast 468 route carrying the Standby extended community) as described in 469 Section 4.1. 471 4.4.2. Inter-AS procedures for ASBRs 473 When an upstream ASBR that receives a C-multicast route, and at least 474 one of the RTs of the route matches one of the ASBR Import RT, and 475 the ASBR locates an Inter-AS I-PMSI A-D route whose RD and Source AS 476 matches the RD and Source AS carried in the C-multicast route, if the 477 route carries the Standby PE BGP Community, then the ASBR performs as 478 follows: 480 o if the route was received over iBGP ; the route is expected to 481 have a LOCAL_PREF attribute set to zero and it should be re- 482 advertized in eBGP with a MED attribute (MULTI_EXIT_DISC) set to 483 the highest possible value (0xffff) 485 o if the route was received over eBGP ; the route is expected to 486 have a MED attribute set of 0xffff and should be re-advertised in 487 iBGP with a LOCAL_PREF attribute set to zero 489 Other ASBR procedures are applied without modification. 491 5. Hot leaf standby 493 The mechanisms defined in the two previous section can be used 494 together as follows. 496 The principle is that, for a said VRF (or possibly only for a said 497 C-S,C-G): 499 o downstream PEs advertise a Standby BGP C-multicast route (based on 500 Section 4) 502 o upstream PEs use the "hot standby" optional behavior and thus will 503 forward traffic for a said multicast state as soon as they have 504 whether a (primary) BGP C-multicast route or a Standby BGP 505 C-multicast route for that state (or both) 507 o downstream PEs accept traffic from the primary or standby tunnel, 508 based on the status of the tunnel (based on Section 3) 510 Other combinations of the mechanisms proposed in Section 4) and 511 Section 3 are for further study. 513 Note that the same level of protection would be achievable with a 514 simple C-multicast Source Tree Join route advertised to both the 515 primary and secondary upstream PEs (carrying as Route Target extended 516 communities, the values of the VRF Route Import attribute of each VPN 517 route from each upstream PEs). The advantage of using the Standby 518 semantic for is that, supposing that downstream PEs always advertise 519 a Standby C-multicast route to the secondary upstream PE, it allows 520 to choose the protection level through a change of configuration on 521 the secondary upstream PE, without requiring any reconfiguration of 522 all the downstream PEs. 524 6. Duplicate packets 526 Multicast VPN specifications [I-D.ietf-l3vpn-2547bis-mcast] impose 527 that a PE only forwards to CEs the packets coming from the expected 528 usptream PE (Section 9.1). 530 We highlight the reader's attention to the fact that the respect of 531 this part of multicast VPN specifications is especially important 532 when two distinct upstream PEs are succeptible to forward the same 533 traffic on P-tunnels at the same time in steady state. This will be 534 the case when "hot root standby" mode is used (Section 4), and which 535 can also be the case if procedures of Section 3 are used and (a) the 536 rules determining the status of a tree are not the same on two 537 distinct downstream PEs or (b) the rule determining the status of a 538 tree depend on conditions local to a PE (e.g. the PE-P upstream link 539 being up). 541 7. IANA Considerations 543 Allocation is expected from IANA for the BGP "Standby PE" community. 544 (TBC) 546 [Note to RFC Editor: this section may be removed on publication as an 547 RFC.] 549 8. Security Considerations 551 9. Acknowledgements 553 The authors want to thank Greg Reaume for its review and useful 554 feedback. 556 10. References 558 10.1. Normative References 560 [I-D.ietf-l3vpn-2547bis-mcast] 561 Aggarwal, R., Bandi, S., Cai, Y., Morin, T., Rekhter, Y., 562 Rosen, E., Wijnands, I., and S. Yasukawa, "Multicast in 563 MPLS/BGP IP VPNs", draft-ietf-l3vpn-2547bis-mcast-08 (work 564 in progress), March 2009. 566 [I-D.ietf-l3vpn-2547bis-mcast-bgp] 567 Aggarwal, R., Rosen, E., Morin, T., and Y. Rekhter, "BGP 568 Encodings and Procedures for Multicast in MPLS/BGP IP 569 VPNs", draft-ietf-l3vpn-2547bis-mcast-bgp-08 (work in 570 progress), September 2009. 572 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 573 Requirement Levels", BCP 14, RFC 2119, March 1997. 575 [RFC4875] Aggarwal, R., Papadimitriou, D., and S. Yasukawa, 576 "Extensions to Resource Reservation Protocol - Traffic 577 Engineering (RSVP-TE) for Point-to-Multipoint TE Label 578 Switched Paths (LSPs)", RFC 4875, May 2007. 580 10.2. Informative References 582 [I-D.ietf-mpls-mcast-cv] 583 Swallow, G., "Connectivity Verification for Multicast 584 Label Switched Paths", draft-ietf-mpls-mcast-cv-00 (work 585 in progress), April 2007. 587 [I-D.karan-mofrr] 588 Karan, A., Filsfils, C., and D. Farinacci, "Multicast only 589 Fast Re-Route", draft-karan-mofrr-00 (work in progress), 590 March 2009. 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 Qiu Ray 643 Alcatel-Lucent 644 701 East Middlefield Rd 645 Mountain View, CA 94043 646 U.S.A. 648 Email: Ray.Qiu@alcatel-lucent.com