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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-14) exists of draft-ietf-bess-evpn-bum-procedure-updates-08 Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 BESS WorkGroup A. Sajassi 3 Internet-Draft S. Thoria 4 Intended status: Standards Track M. Mishra 5 Expires: January 6, 2022 Cisco Systems 6 K. Patel 7 Arrcus 8 J. Drake 9 W. Lin 10 Juniper Networks 11 July 5, 2021 13 IGMP and MLD Proxy for EVPN 14 draft-ietf-bess-evpn-igmp-mld-proxy-11 16 Abstract 18 Ethernet Virtual Private Network (EVPN) solution is becoming 19 pervasive in data center (DC) applications for Network Virtualization 20 Overlay (NVO) and DC interconnect (DCI) services, and in service 21 provider (SP) applications for next generation virtual private LAN 22 services. 24 This draft describes how to support efficiently endpoints running 25 IGMP for the above services over an EVPN network by incorporating 26 IGMP proxy procedures on EVPN PEs. 28 Status of This Memo 30 This Internet-Draft is submitted in full conformance with the 31 provisions of BCP 78 and BCP 79. 33 Internet-Drafts are working documents of the Internet Engineering 34 Task Force (IETF). Note that other groups may also distribute 35 working documents as Internet-Drafts. The list of current Internet- 36 Drafts is at https://datatracker.ietf.org/drafts/current/. 38 Internet-Drafts are draft documents valid for a maximum of six months 39 and may be updated, replaced, or obsoleted by other documents at any 40 time. It is inappropriate to use Internet-Drafts as reference 41 material or to cite them other than as "work in progress." 43 This Internet-Draft will expire on January 6, 2022. 45 Copyright Notice 47 Copyright (c) 2021 IETF Trust and the persons identified as the 48 document authors. All rights reserved. 50 This document is subject to BCP 78 and the IETF Trust's Legal 51 Provisions Relating to IETF Documents 52 (https://trustee.ietf.org/license-info) in effect on the date of 53 publication of this document. Please review these documents 54 carefully, as they describe your rights and restrictions with respect 55 to this document. Code Components extracted from this document must 56 include Simplified BSD License text as described in Section 4.e of 57 the Trust Legal Provisions and are provided without warranty as 58 described in the Simplified BSD License. 60 Table of Contents 62 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 63 2. Specification of Requirements . . . . . . . . . . . . . . . . 4 64 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 65 4. IGMP/MLD Proxy . . . . . . . . . . . . . . . . . . . . . . . 6 66 4.1. Proxy Reporting . . . . . . . . . . . . . . . . . . . . . 6 67 4.1.1. IGMP/MLD Membership Report Advertisement in BGP . . . 6 68 4.1.2. IGMP/MLD Leave Group Advertisement in BGP . . . . . . 8 69 4.2. Proxy Querier . . . . . . . . . . . . . . . . . . . . . . 9 70 5. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 9 71 5.1. PE with only attached hosts/VMs for a given subnet . . . 10 72 5.2. PE with a mix of attached hosts/VMs and multicast source 11 73 5.3. PE with a mix of attached hosts/VMs, a multicast source 74 and a router . . . . . . . . . . . . . . . . . . . . . . 11 75 6. All-Active Multi-Homing . . . . . . . . . . . . . . . . . . . 11 76 6.1. Local IGMP/MLD Join Synchronization . . . . . . . . . . . 11 77 6.2. Local IGMP/MLD Leave Group Synchronization . . . . . . . 12 78 6.2.1. Remote Leave Group Synchronization . . . . . . . . . 13 79 6.2.2. Common Leave Group Synchronization . . . . . . . . . 13 80 6.3. Mass Withdraw of Multicast join Sync route in case of 81 failure . . . . . . . . . . . . . . . . . . . . . . . . . 14 82 7. Single-Active Multi-Homing . . . . . . . . . . . . . . . . . 14 83 8. Selective Multicast Procedures for IR tunnels . . . . . . . . 14 84 9. BGP Encoding . . . . . . . . . . . . . . . . . . . . . . . . 15 85 9.1. Selective Multicast Ethernet Tag Route . . . . . . . . . 15 86 9.1.1. Constructing the Selective Multicast Ethernet Tag 87 route . . . . . . . . . . . . . . . . . . . . . . . . 17 88 9.1.2. Default Selective Multicast Route . . . . . . . . . . 18 89 9.2. Multicast Join Synch Route . . . . . . . . . . . . . . . 19 90 9.2.1. Constructing the Multicast Join Synch Route . . . . . 21 91 9.3. Multicast Leave Synch Route . . . . . . . . . . . . . . . 22 92 9.3.1. Constructing the Multicast Leave Synch Route . . . . 24 94 9.4. Multicast Flags Extended Community . . . . . . . . . . . 25 95 9.5. EVI-RT Extended Community . . . . . . . . . . . . . . . . 27 96 9.6. Rewriting of RT ECs and EVI-RT ECs by ASBRs . . . . . . . 29 97 9.7. BGP Error Handling . . . . . . . . . . . . . . . . . . . 29 98 10. IGMP/MLD Immediate Leave . . . . . . . . . . . . . . . . . . 29 99 11. IGMP Version 1 Membership Report . . . . . . . . . . . . . . 30 100 12. Security Considerations . . . . . . . . . . . . . . . . . . . 30 101 13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 30 102 14. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 31 103 15. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 31 104 16. References . . . . . . . . . . . . . . . . . . . . . . . . . 31 105 16.1. Normative References . . . . . . . . . . . . . . . . . . 31 106 16.2. Informative References . . . . . . . . . . . . . . . . . 33 107 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 33 109 1. Introduction 111 Ethernet Virtual Private Network (EVPN) solution [RFC7432] is 112 becoming pervasive in data center (DC) applications for Network 113 Virtualization Overlay (NVO) and DC interconnect (DCI) services, and 114 in service provider (SP) applications for next generation virtual 115 private LAN services. 117 In DC applications, a point of delivery (POD) can consist of a 118 collection of servers supported by several top of rack (TOR) and 119 Spine switches. This collection of servers and switches are self 120 contained and may have their own control protocol for intra-POD 121 communication and orchestration. However, EVPN is used as standard 122 way of inter-POD communication for both intra-DC and inter-DC. A 123 subnet can span across multiple PODs and DCs. EVPN provides robust 124 multi-tenant solution with extensive multi-homing capabilities to 125 stretch a subnet (VLAN) across multiple PODs and DCs. There can be 126 many hosts/VMs(virtual machine) (several hundreds) attached to a 127 subnet that is stretched across several PODs and DCs. 129 These hosts/VMs express their interests in multicast groups on a 130 given subnet/VLAN by sending IGMP Membership Reports (Joins) for 131 their interested multicast group(s). Furthermore, an IGMP router 132 periodically sends membership queries to find out if there are hosts 133 on that subnet that are still interested in receiving multicast 134 traffic for that group. The IGMP/MLD Proxy solution described in 135 this draft accomplishes three objectives: 137 1. Reduce flooding of IGMP messages: just like the ARP/ND 138 suppression mechanism in EVPN to reduce the flooding of ARP 139 messages over EVPN, it is also desired to have a mechanism to 140 reduce the flooding of IGMP messages (both Queries and Reports) 141 in EVPN. 143 2. Distributed anycast multicast proxy: it is desirable for the EVPN 144 network to act as a distributed anycast multicast router with 145 respect to IGMP/MLD proxy function for all the hosts attached to 146 that subnet. 148 3. Selective Multicast: to forward multicast traffic over EVPN 149 network such that it only gets forwarded to the PEs that have 150 interest in the multicast group(s), multicast traffic will not be 151 forwarded to the PEs that have no receivers attached to them for 152 that multicast group. This draft shows how this objective may be 153 achieved when Ingress Replication is used to distribute the 154 multicast traffic among the PEs. Procedures for supporting 155 selective multicast using P2MP tunnels can be found in 156 [I-D.ietf-bess-evpn-bum-procedure-updates] 158 The first two objectives are achieved by using IGMP/MLD proxy on the 159 PE and the third objective is achieved by setting up a multicast 160 tunnel (e.g., ingress replication) only among the PEs that have 161 interest in that multicast group(s) based on the trigger from IGMP/ 162 MLD proxy processes. The proposed solutions for each of these 163 objectives are discussed in the following sections. 165 2. Specification of Requirements 167 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 168 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 169 "OPTIONAL" in this document are to be interpreted as described in BCP 170 14 [RFC2119] [RFC8174] when, and only when, they appear in all 171 capitals, as shown here. 173 3. Terminology 175 o POD: Point of Delivery 177 o ToR: Top of Rack 179 o NV: Network Virtualization 181 o NVO: Network Virtualization Overlay 183 o EVPN: Ethernet Virtual Private Network 185 o IGMP: Internet Group Management Protocol 187 o MLD: Multicast Listener Discovery 189 o EVI: An EVPN instance spanning the Provider Edge (PE) devices 190 participating in that EVPN 192 o MAC-VRF: A Virtual Routing and Forwarding table for Media Access 193 Control (MAC) addresses on a PE 195 o IR: Ingress Replication 197 o Ethernet Segment (ES): When a customer site (device or network) is 198 connected to one or more PEs via a set of Ethernet links, then 199 that set of links is referred to as an 'Ethernet Segment'. 201 o Ethernet Segment Identifier (ESI): A unique non-zero identifier 202 that identifies an Ethernet Segment is called an 'Ethernet Segment 203 Identifier'. 205 o PE: Provider Edge. 207 o BD: Broadcast Domain. As per [RFC7432], an EVI consists of a 208 single or multiple BDs. In case of VLAN-bundle and VLAN-aware 209 bundle service model, an EVI contains multiple BDs. Also, in this 210 document, BD and subnet are equivalent terms. 212 o Ethernet Tag: An Ethernet tag identifies a particular broadcast 213 domain, e.g., a VLAN. An EVPN instance consists of one or more 214 broadcast domains. 216 o Single-Active Redundancy Mode: When only a single PE, among all 217 the PEs attached to an Ethernet segment, is allowed to forward 218 traffic to/from that Ethernet segment for a given VLAN, then the 219 Ethernet segment is defined to be operating in Single-Active 220 redundancy mode. 222 o All-Active Redundancy Mode: When all PEs attached to an Ethernet 223 segment are allowed to forward known unicast traffic to/from that 224 Ethernet segment for a given VLAN, then the Ethernet segment is 225 defined to be operating in All-Active redundancy mode. 227 o PMSI: P-Multicast Service Interface - a conceptual interface for a 228 PE to send customer multicast traffic to all or some PEs in the 229 same VPN. 231 o S-PMSI: Selective PMSI - to some of the PEs in the same VPN. 233 o AC: Attachment Circuit. 235 o OIF: Outgoing Interface 237 This document also assumes familiarity with the terminology of 238 [RFC7432]. Though most of the place this document uses term IGMP 239 Membership Report (Joins), the text applies equally for MLD 240 Membership Report too. Similarly, text for IGMPv2 applies to MLDv1 241 and text for IGMPv3 applies to MLDv2. IGMP / MLD version encoding in 242 BGP update is stated in Section 9 244 4. IGMP/MLD Proxy 246 The IGMP Proxy mechanism is used to reduce the flooding of IGMP 247 messages over an EVPN network similar to ARP proxy used in reducing 248 the flooding of ARP messages over EVPN. It also provides a 249 triggering mechanism for the PEs to setup their underlay multicast 250 tunnels. The IGMP Proxy mechanism consists of two components: 252 1. Proxy for IGMP Reports. 254 2. Proxy for IGMP Queries. 256 4.1. Proxy Reporting 258 When IGMP protocol is used between hosts/VMs and their first hop EVPN 259 router (EVPN PE), Proxy-reporting is used by the EVPN PE to summarize 260 (when possible) reports received from downstream hosts and propagate 261 them in BGP to other PEs that are interested in the information. 262 This is done by terminating the IGMP Reports in the first hop PE, and 263 translating and exchanging the relevant information among EVPN BGP 264 speakers. The information is again translated back to IGMP message 265 at the recipient EVPN speaker. Thus it helps create an IGMP overlay 266 subnet using BGP. In order to facilitate such an overlay, this 267 document also defines a new EVPN route type NLRI, the EVPN Selective 268 Multicast Ethernet Tag route, along with its procedures to help 269 exchange and register IGMP multicast groups Section 9. 271 4.1.1. IGMP/MLD Membership Report Advertisement in BGP 273 When a PE wants to advertise an IGMP Membership Report (Join) using 274 the BGP EVPN route, it follows the following rules (BGP encoding 275 stated in Section 9): 277 1. When the first hop PE receives several IGMP Membership Reports 278 (Joins), belonging to the same IGMP version, from different 279 attached hosts/VMs for the same (*,G) or (S,G), it SHOULD send a 280 single BGP message corresponding to the very first IGMP 281 Membership Request (BGP update as soon as possible) for that 282 (*,G) or (S,G). This is because BGP is a stateful protocol and 283 no further transmission of the same report is needed. If the 284 IGMP Membership Request is for (*,G), then multicast group 285 address MUST be sent along with the corresponding version flag 286 (v2 or v3) set. In case of IGMPv3, the exclude flag MUST also be 287 set to indicate that no source IP address must be excluded 288 (include all sources"*"). If the IGMP Join is for (S,G), then 289 besides setting multicast group address along with the version 290 flag v3, the source IP address and the IE flag MUST be set. It 291 should be noted that when advertising the EVPN route for (S,G), 292 the only valid version flag is v3 (v2 flags MUST be set to zero). 294 2. When the first hop PE receives an IGMPv3 Join for (S,G) on a 295 given BD, it SHOULD advertise the corresponding EVPN Selective 296 Multicast Ethernet Tag (SMET) route regardless of whether the 297 source (S) is attached to itself or not in order to facilitate 298 the source move in the future. 300 3. When the first hop PE receives an IGMP version-X Join first for 301 (*,G) and then later it receives an IGMP version-Y Join for the 302 same (*,G), then it MUST re-advertise the same EVPN SMET route 303 with flag for version-Y set in addition to any previously-set 304 version flag(s). In other words, the first hop PE MUST NOT 305 withdraw the EVPN route before sending the new route because the 306 flag field is not part of BGP route key processing. 308 4. When the first hop PE receives an IGMP version-X Join first for 309 (*,G) and then later it receives an IGMPv3 Join for the same 310 multicast group address but for a specific source address S, then 311 the PE MUST advertise a new EVPN SMET route with v3 flag set (and 312 v2 reset). The IE flag also need to be set accordingly. Since 313 source IP address is used as part of BGP route key processing it 314 is considered as a new BGP route advertisement. 316 5. When a PE receives an EVPN SMET route with more than one version 317 flag set, it will generate the corresponding IGMP report for 318 (*,G) for each version specified in the flags field. With 319 multiple version flags set, there must not be source IP address 320 in the received EVPN route. If there is, then an error SHOULD be 321 logged. If the v3 flag is set (in addition to v2), then the IE 322 flag MUST indicate "exclude". If not, then an error SHOULD be 323 logged. The PE MUST generate an IGMP Membership Report (Join) 324 for that (*,G) and each IGMP version in the version flag. 326 6. When a PE receives a list of EVPN SMET NLRIs in its BGP update 327 message, each with a different source IP address and the same 328 multicast group address, and the version flag is set to v3, then 329 the PE generates an IGMPv3 Membership Report with a record 330 corresponding to the list of source IP addresses and the group 331 address along with the proper indication of inclusion/exclusion. 333 7. Upon receiving EVPN SMET route(s) and before generating the 334 corresponding IGMP Membership Request(s), the PE checks to see 335 whether it has any CE multicast router for that BD on any of its 336 ES's . The PE provides such a check by listening for PIM Hello 337 messages on that AC (i.e, ES,BD). If the PE does have the 338 router's ACs, then the generated IGMP Membership Request(s) are 339 sent to those ACs. If it doesn't have any of the router's AC, 340 then no IGMP Membership Request(s) needs to be generated. This 341 is because sending IGMP Membership Requests to other hosts can 342 result in unintentionally preventing a host from joining a 343 specific multicast group using IGMPv2 - i.e., if the PE does not 344 receive a join from the host it will not forward multicast data 345 to it. Per [RFC4541] , when an IGMPv2 host receives a Membership 346 Report for a group address that it intends to join, the host will 347 suppress its own membership report for the same group, and if the 348 PE does not receive an IGMP Join from host it will not forward 349 multicast data to it. In other words, an IGMPv2 Join MUST NOT be 350 sent on an AC that does not lead to a CE multicast router. This 351 message suppression is a requirement for IGMPv2 hosts. This is 352 not a problem for hosts running IGMPv3 because there is no 353 suppression of IGMP Membership Reports. 355 4.1.2. IGMP/MLD Leave Group Advertisement in BGP 357 When a PE wants to withdraw an EVPN SMET route corresponding to an 358 IGMPv2 Leave Group (Leave) or IGMPv3 "Leave" equivalent message, it 359 follows the following rules: 361 1. When a PE receives an IGMPv2 Leave Group or its "Leave" 362 equivalent message for IGMPv3 from its attached host, it checks 363 to see if this host is the last host that is interested in this 364 multicast group by sending a query for the multicast group. If 365 the host was indeed the last one (i.e. no responses are received 366 for the query), then the PE MUST re-advertises EVPN SMET 367 Multicast route with the corresponding version flag reset. If 368 this is the last version flag to be reset, then instead of re- 369 advertising the EVPN route with all version flags reset, the PE 370 MUST withdraw the EVPN route for that (*,G). 372 2. When a PE receives an EVPN SMET route for a given (*,G), it 373 compares the received version flags from the route with its per- 374 PE stored version flags. If the PE finds that a version flag 375 associated with the (*,G) for the remote PE is reset, then the PE 376 MUST generate IGMP Leave for that (*,G) toward its local 377 interface (if any) attached to the multicast router for that 378 multicast group. It should be noted that the received EVPN route 379 SHOULD at least have one version flag set. If all version flags 380 are reset, it is an error because the PE should have received an 381 EVPN route withdraw for the last version flag. Error MUST be 382 considered as BGP error and the PE MUST apply the "treat-as- 383 withdraw" procedure of [RFC7606]. 385 3. When a PE receives an EVPN SMET route withdraw, it removes the 386 remote PE from its OIF list for that multicast group and if there 387 are no more OIF entries for that multicast group (either locally 388 or remotely), then the PE MUST stop responding to queries from 389 the locally attached router (if any). If there is a source for 390 that multicast group, the PE stops sending multicast traffic for 391 that source. 393 4.2. Proxy Querier 395 As mentioned in the previous sections, each PE MUST have proxy 396 querier functionality for the following reasons: 398 1. To enable the collection of EVPN PEs providing L2VPN service to 399 act as distributed multicast router with Anycast IP address for 400 all attached hosts/VMs in that subnet. 402 2. To enable suppression of IGMP Membership Reports and queries over 403 MPLS/IP core. 405 5. Operation 407 Consider the EVPN network of Figure-1, where there is an EVPN 408 instance configured across the PEs shown in this figure (namely PE1, 409 PE2, and PE3). Let's consider that this EVPN instance consists of a 410 single bridge domain (single subnet) with all the hosts, sources, and 411 the multicast router connected to this subnet. PE1 only has hosts 412 connected to it. PE2 has a mix of hosts and a multicast source. PE3 413 has a mix of hosts, a multicast source, and a multicast router. 414 Furthermore, let's consider that for (S1,G1), R1 is used as the 415 multicast router. The following subsections describe the IGMP proxy 416 operation in different PEs with regard to whether the locally 417 attached devices for that subnet are: 419 o only hosts/VMs 421 o mix of hosts/VMs and multicast source 423 o mix of hosts/VMs, multicast source, and multicast router 424 +--------------+ 425 | | 426 | | 427 +----+ | | +----+ 428 H1:(*,G1)v2 ---| | | | | |---- H6(*,G1)v2 429 H2:(*,G1)v2 ---| PE1| | IP/MPLS | | PE2|---- H7(S2,G2)v3 430 H3:(*,G1)v3 ---| | | Network | | |---- S2 431 H4:(S2,G2)v3 --| | | | | | 432 +----+ | | +----+ 433 | | 434 +----+ | | 435 H5:(S1,G1)v3 --| | | | 436 S1 ---| PE3| | | 437 R1 ---| | | | 438 +----+ | | 439 | | 440 +--------------+ 442 Figure 1: EVPN network 444 5.1. PE with only attached hosts/VMs for a given subnet 446 When PE1 receives an IGMPv2 Membership Report from H1, it does not 447 forward this join to any of its other ports (for this subnet) because 448 all these local ports are associated with the hosts/VMs. PE1 sends 449 an EVPN Multicast Group route corresponding to this join for (*,G1) 450 and setting v2 flag. This EVPN route is received by PE2 and PE3 that 451 are the members of the same BD (i.e., same EVI in case of VLAN-based 452 service or EVI,VLAN in case of VLAN-aware bundle service). PE3 453 reconstructs the IGMPv2 Membership Report from this EVPN BGP route 454 and only sends it to the port(s) with multicast routers attached to 455 it (for that subnet). In this example, PE3 sends the reconstructed 456 IGMPv2 Membership Report for (*,G1) only to R1. Furthermore, even 457 though PE2 receives the EVPN BGP route, it does not send it to any of 458 its ports for that subnet; viz, ports associated with H6 and H7. 460 When PE1 receives the second IGMPv2 Join from H2 for the same 461 multicast group (*,G1), it only adds that port to its OIF list but it 462 doesn't send any EVPN BGP route because there is no change in 463 information. However, when it receives the IGMPv3 Join from H3 for 464 the same (*,G1). Besides adding the corresponding port to its OIF 465 list, it re-advertises the previously sent EVPN SMET route with the 466 v3 and exclude flag set. 468 Finally when PE1 receives the IGMPv3 Join from H4 for (S2,G2), it 469 advertises a new EVPN SMET route corresponding to it. 471 5.2. PE with a mix of attached hosts/VMs and multicast source 473 The main difference in this case is that when PE2 receives the IGMPv3 474 Join from H7 for (S2,G2), it does advertise it in BGP to support 475 source move even though PE2 knows that S2 is attached to its local 476 AC. PE2 adds the port associated with H7 to its OIF list for 477 (S2,G2). The processing for IGMPv2 received from H6 is the same as 478 the IGMPv2 Join described in previous section. 480 5.3. PE with a mix of attached hosts/VMs, a multicast source and a 481 router 483 The main difference in this case relative to the previous two 484 sections is that IGMP v2/v3 Join messages received locally need to be 485 sent to the port associated with router R1. Furthermore, the Joins 486 received via BGP (SMET) need to be passed to the R1 port but filtered 487 for all other ports. 489 6. All-Active Multi-Homing 491 Because the LAG flow hashing algorithm used by the CE is unknown at 492 the PE, in an All-Active redundancy mode it must be assumed that the 493 CE can send a given IGMP message to any one of the multi-homed PEs, 494 either DF or non-DF; i.e., different IGMP Membership Request messages 495 can arrive at different PEs in the redundancy group and furthermore 496 their corresponding Leave messages can arrive at PEs that are 497 different from the ones that received the Join messages. Therefore, 498 all PEs attached to a given ES must coordinate IGMP Membership 499 Request and Leave Group (x,G) state, where x may be either '*' or a 500 particular source S, for each BD on that ES. This allows the DF for 501 that (ES,BD) to correctly advertise or withdraw a Selective Multicast 502 Ethernet Tag (SMET) route for that (x,G) group in that BD when 503 needed. All-Active multihoming PEs for a given ES MUST support IGMP 504 synchronization procedures described in this section if they need to 505 perform IGMP proxy for hosts connected to that ES. 507 6.1. Local IGMP/MLD Join Synchronization 509 When a PE, either DF or non-DF, receives on a given multihomed ES 510 operating in All-Active redundancy mode, an IGMP Membership Report 511 for (x,G), it determines the BD to which the IGMP Membership Report 512 belongs. If the PE doesn't already have local IGMP Membership 513 Request (x,G) state for that BD on that ES, it MUST instantiate local 514 IGMP Membership Request (x,G) state and MUST advertise a BGP IGMP 515 Join Synch route for that (ES,BD). Local IGMP Membership Request 516 (x,G) state refers to IGMP Membership Request (x,G) state that is 517 created as a result of processing an IGMP Membership Report for 518 (x,G). 520 The IGMP Join Synch route MUST carry the ES-Import RT for the ES on 521 which the IGMP Membership Report was received. Thus it MUST only be 522 imported by the PEs attached to that ES and not any other PEs. 524 When a PE, either DF or non-DF, receives an IGMP Join Synch route it 525 installs that route and if it doesn't already have IGMP Membership 526 Request (x,G) state for that (ES,BD), it MUST instantiate that IGMP 527 Membership Request (x,G) state - i.e., IGMP Membership Request (x,G) 528 state is the union of the local IGMP Join (x,G) state and the 529 installed IGMP Join Synch route. If the DF did not already advertise 530 (originate) a SMET route for that (x,G) group in that BD, it MUST do 531 so now. 533 When a PE, either DF or non-DF, deletes its local IGMP Membership 534 Request (x,G) state for that (ES,BD), it MUST withdraw its BGP IGMP 535 Join Synch route for that (ES,BD). 537 When a PE, either DF or non-DF, receives the withdrawal of an IGMP 538 Join Synch route from another PE it MUST remove that route. When a 539 PE has no local IGMP Membership Request (x,G) state and it has no 540 installed IGMP Join Synch routes, it MUST remove IGMP Membership 541 Request (x,G) state for that (ES,BD). If the DF no longer has IGMP 542 Membership Request (x,G) state for that BD on any ES for which it is 543 DF, it MUST withdraw its SMET route for that (x,G) group in that BD. 545 In other words, a PE advertises an SMET route for that (x,G) group in 546 that BD when it has IGMP Membership Request (x,G) state in that BD on 547 at least one ES for which it is DF and it withdraws that SMET route 548 when it does not have IGMP Membership Request (x,G) state in that BD 549 on any ES for which it is DF. 551 6.2. Local IGMP/MLD Leave Group Synchronization 553 When a PE, either DF or non-DF, receives, on a given multihomed ES 554 operating in All-Active redundancy mode, an IGMP Leave Group message 555 for (x,G) from the attached CE, it determines the BD to which the 556 IGMPv2 Leave Group belongs. Regardless of whether it has IGMP 557 Membership Request (x,G) state for that (ES,BD), it initiates the 558 (x,G) leave group synchronization procedure, which consists of the 559 following steps: 561 1. It computes the Maximum Response Time, which is the duration of 562 (x,G) leave group synchronization procedure. This is the product 563 of two locally configured values, Last Member Query Count and 564 Last Member Query Interval (described in Section 3 of [RFC2236]), 565 plus a delta corresponding to the time it takes for a BGP 566 advertisement to propagate between the PEs attached to the 567 multihomed ES (delta is a consistently configured value on all 568 PEs attached to the multihomed ES). 570 2. It starts the Maximum Response Time timer. Note that the receipt 571 of subsequent IGMP Leave Group messages or BGP Leave Synch routes 572 for (x,G) do not change the value of a currently running Maximum 573 Response Time timer and are ignored by the PE. 575 3. It initiates the Last Member Query procedure described in 576 Section 3 of [RFC2236]; viz, it sends a number of Group-Specific 577 Query (x,G) messages (Last Member Query Count) at a fixed 578 interval (Last Member Query Interval) to the attached CE. 580 4. It advertises an IGMP Leave Synch route for that that (ES,BD). 581 This route notifies the other multihomed PEs attached to the 582 given multihomed ES that it has initiated an (x,G) leave group 583 synchronization procedure; i.e., it carries the ES-Import RT for 584 the ES on which the IGMP Leave Group was received. It also 585 contains the Maximum Response Time. 587 5. When the Maximum Response Timer expires, the PE that has 588 advertised the IGMP Leave Synch route withdraws it. 590 6.2.1. Remote Leave Group Synchronization 592 When a PE, either DF or non-DF, receives an IGMP Leave Synch route it 593 installs that route and it starts a timer for (x,G) on the specified 594 (ES,BD) whose value is set to the Maximum Response Time in the 595 received IGMP Leave Synch route. Note that the receipt of subsequent 596 IGMPv2 Leave Group messages or BGP Leave Synch routes for (x,G) do 597 not change the value of a currently running Maximum Response Time 598 timer and are ignored by the PE. 600 6.2.2. Common Leave Group Synchronization 602 If a PE attached to the multihomed ES receives an IGMP Membership 603 Report for (x,G) before the Maximum Response Time timer expires, it 604 advertises a BGP IGMP Join Synch route for that (ES,BD). If it 605 doesn't already have local IGMP Membership Request (x,G) state for 606 that (ES,BD), it instantiates local IGMP Membership Request (x,G) 607 state. If the DF is not currently advertising (originating) a SMET 608 route for that (x,G) group in that BD, it does so now. 610 If a PE attached to the multihomed ES receives an IGMP Join Synch 611 route for (x,G) before the Maximum Response Time timer expires, it 612 installs that route and if it doesn't already have IGMP Membership 613 Request (x,G) state for that BD on that ES, it instantiates that IGMP 614 Membership Request (x,G) state. If the DF has not already advertised 615 (originated) a SMET route for that (x,G) group in that BD, it does so 616 now. 618 When the Maximum Response Timer expires a PE that has advertised an 619 IGMP Leave Synch route, withdraws it. Any PE attached to the 620 multihomed ES, that started the Maximum Response Time and has no 621 local IGMP Membership Request (x,G) state and no installed IGMP Join 622 Synch routes, it removes IGMP Membership Request (x,G) state for that 623 (ES,BD). If the DF no longer has IGMP Membership Request (x,G) state 624 for that BD on any ES for which it is DF, it withdraws its SMET route 625 for that (x,G) group in that BD. 627 6.3. Mass Withdraw of Multicast join Sync route in case of failure 629 A PE which has received an IGMP Membership Request, would have synced 630 the IGMP Join by the procedure defined in section 6.1. If a PE with 631 local join state goes down or the PE to CE link goes down, it would 632 lead to a mass withdraw of multicast routes. Remote PEs (PEs where 633 these routes were remote IGMP Joins) SHOULD NOT remove the state 634 immediately; instead General Query SHOULD be generated to refresh the 635 states. There are several ways to detect failure at a peer, e.g. 636 using IGP next hop tracking or ES route withdraw. 638 7. Single-Active Multi-Homing 640 Note that to facilitate state synchronization after failover, the PEs 641 attached to a multihomed ES operating in Single-Active redundancy 642 mode SHOULD also coordinate IGMP Join (x,G) state. In this case all 643 IGMP Join messages are received by the DF and distributed to the non- 644 DF PEs using the procedures described above. 646 8. Selective Multicast Procedures for IR tunnels 648 If an ingress PE uses ingress replication, then for a given (x,G) 649 group in a given BD: 651 1. It sends (x,G) traffic to the set of PEs not supporting IGMP 652 Proxy. This set consists of any PE that has advertised an 653 Inclusive Multicast Tag route for the BD without the "IGMP Proxy 654 Support" flag. 656 2. It sends (x,G) traffic to the set of PEs supporting IGMP Proxy 657 and having listeners for that (x,G) group in that BD. This set 658 consists of any PE that has advertised an Inclusive Multicast 659 Ethernet Tag route for the BD with the "IGMP Proxy Support" flag 660 and that has advertised a SMET route for that (x,G) group in that 661 BD. 663 If an ingress PE's Selective P-Tunnel for a given BD uses P2MP and 664 all of the PEs in the BD support that tunnel type and IGMP proxy, 665 then for a given (x,G) group in a given BD it sends (x,G) traffic 666 using the Selective P-Tunnel for that (x,G) group in that BD. This 667 tunnel includes those PEs that have advertised a SMET route for that 668 (x,G) group on that BD (for Selective P-tunnel) but it may include 669 other PEs as well (for Aggregate Selective P-tunnel). 671 9. BGP Encoding 673 This document defines three new BGP EVPN routes to carry IGMP 674 Membership Reports. The route types are known as: 676 + 6 - Selective Multicast Ethernet Tag Route 678 + 7 - Multicast Join Synch Route 680 + 8 - Multicast Leave Synch Route 682 The detailed encoding and procedures for these route types are 683 described in subsequent sections. 685 9.1. Selective Multicast Ethernet Tag Route 687 A Selective Multicast Ethernet Tag route type specific EVPN NLRI 688 consists of the following: 690 +---------------------------------------+ 691 | RD (8 octets) | 692 +---------------------------------------+ 693 | Ethernet Tag ID (4 octets) | 694 +---------------------------------------+ 695 | Multicast Source Length (1 octet) | 696 +---------------------------------------+ 697 | Multicast Source Address (variable) | 698 +---------------------------------------+ 699 | Multicast Group Length (1 octet) | 700 +---------------------------------------+ 701 | Multicast Group Address (Variable) | 702 +---------------------------------------+ 703 | Originator Router Length (1 octet) | 704 +---------------------------------------+ 705 | Originator Router Address (variable) | 706 +---------------------------------------+ 707 | Flags (1 octet) | 708 +---------------------------------------+ 710 For the purpose of BGP route key processing, all the fields are 711 considered to be part of the prefix in the NLRI except for the one- 712 octet flag field. The Flags fields are defined as follows: 714 0 1 2 3 4 5 6 7 715 +--+--+--+--+--+--+--+--+ 716 | reserved |IE|v3|v2|v1| 717 +--+--+--+--+--+--+--+--+ 719 o The least significant bit, bit 7 indicates support for IGMP 720 version 1. Since IGMP V1 is being deprecated , sender MUST set it 721 as 0 for IGMP and receiver MUST ignore it. 723 o The second least significant bit, bit 6 indicates support for IGMP 724 version 2. 726 o The third least significant bit, bit 5 indicates support for IGMP 727 version 3. 729 o The fourth least significant bit, bit 4 indicates whether the 730 (S,G) information carried within the route-type is of an Include 731 Group type (bit value 0) or an Exclude Group type (bit value 1). 732 The Exclude Group type bit MUST be ignored if bit 5 is not set. 734 o This EVPN route type is used to carry tenant IGMP multicast group 735 information. The flag field assists in distributing IGMP 736 Membership Report of a given host/VM for a given multicast route. 737 The version bits help associate IGMP version of receivers 738 participating within the EVPN domain. 740 o The include/exclude bit helps in creating filters for a given 741 multicast route. 743 o If route is used for IPv6 (MLD) then bit 7 indicates support for 744 MLD version 1. The second least significant bit, bit 6 indicates 745 support for MLD version 2. Since there is no MLD version 3, in 746 case of IPv6 route third least significant bit MUST be 0. In case 747 of IPv6 routes, the fourth least significant bit MUST be ignored 748 if bit 6 is not set. 750 o Reserved bits SHOULD be set to 0 by sender. And receiver SHOULD 751 ignore the Reserved bits. 753 9.1.1. Constructing the Selective Multicast Ethernet Tag route 755 This section describes the procedures used to construct the Selective 756 Multicast Ethernet Tag (SMET) route. 758 The Route Distinguisher (RD) SHOULD be a Type 1 RD [RFC4364]. The 759 value field comprises an IP address of the PE (typically, the 760 loopback address) followed by a number unique to the PE. 762 The Ethernet Tag ID MUST be set as procedure defined in [RFC7432]. 764 The Multicast Source Length MUST be set to length of the multicast 765 Source address in bits. If the Multicast Source Address field 766 contains an IPv4 address, then the value of the Multicast Source 767 Length field is 32. If the Multicast Source Address field contains 768 an IPv6 address, then the value of the Multicast Source Length field 769 is 128. In case of a (*,G) Join, the Multicast Source Length is set 770 to 0. 772 The Multicast Source Address is the source IP address from the IGMP 773 Membership Report. In case of a (*,G), this field is not used. 775 The Multicast Group Length MUST be set to length of multicast group 776 address in bits. If the Multicast Group Address field contains an 777 IPv4 address, then the value of the Multicast Group Length field is 778 32. If the Multicast Group Address field contains an IPv6 address, 779 then the value of the Multicast Group Length field is 128. 781 The Multicast Group Address is the Group address from the IGMP or MLD 782 Membership Report. 784 The Originator Router Length is the length of the Originator Router 785 Address in bits. 787 The Originator Router Address is the IP address of router originating 788 this route. The SMET Originator Router IP address MUST match that of 789 the IMET (or S-PMSI AD) route originated for the same EVI by the same 790 downstream PE. 792 The Flags field indicates the version of IGMP protocol from which the 793 Membership Report was received. It also indicates whether the 794 multicast group had the INCLUDE or EXCLUDE bit set. 796 Reserved bits MUST be set to 0. They can be defined in future by 797 other document. 799 IGMP is used to receive group membership information from hosts/VMs 800 by TORs. Upon receiving the hosts/VMs expression of interest of a 801 particular group membership, this information is then forwarded using 802 SMET route. The NLRI also keeps track of receiver's IGMP protocol 803 version and any source filtering for a given group membership. All 804 EVPN SMET routes are announced with per- EVI Route Target extended 805 communities. 807 9.1.2. Default Selective Multicast Route 809 If there is multicast router connected behind the EVPN domain, the PE 810 MAY originate a default SMET (*,*) to get all multicast traffic in 811 domain. 813 +--------------+ 814 | | 815 | | 816 | | +----+ 817 | | | |---- H1(*,G1)v2 818 | IP/MPLS | | PE1|---- H2(S2,G2)v3 819 | Network | | |---- S2 820 | | | | 821 | | +----+ 822 | | 823 +----+ | | 824 +----+ | | | | 825 | | S1 ---| PE2| | | 826 |PIM |----R1 ---| | | | 827 |ASM | +----+ | | 828 | | | | 829 +----+ +--------------+ 831 Figure 2: Multicast Router behind EVPN domain 833 Consider the EVPN network of Figure-2, where there is an EVPN 834 instance configured across the PEs. Lets consider PE2 is connected 835 to multicast router R1 and there is a network running PIM ASM behind 836 R1. If there are receivers behind the PIM ASM network, the PIM Join 837 would be forwarded to the PIM RP (Rendezvous Point). If receivers 838 behind PIM ASM network are interested in a multicast flow originated 839 by multicast source S2 (behind PE1), it is necessary for PE2 to 840 receive multicast traffic. In this case PE2 MUST originate a (*,*) 841 SMET route to receive all of the multicast traffic in the EVPN 842 domain. To generate Wildcards (*,*) routes, prcedure from [RFC6625] 843 SHOULD be used. 845 9.2. Multicast Join Synch Route 847 This EVPN route type is used to coordinate IGMP Join (x,G) state for 848 a given BD between the PEs attached to a given ES operating in All- 849 Active (or Single-Active) redundancy mode and it consists of 850 following: 852 +--------------------------------------------------+ 853 | RD (8 octets) | 854 +--------------------------------------------------+ 855 | Ethernet Segment Identifier (10 octets) | 856 +--------------------------------------------------+ 857 | Ethernet Tag ID (4 octets) | 858 +--------------------------------------------------+ 859 | Multicast Source Length (1 octet) | 860 +--------------------------------------------------+ 861 | Multicast Source Address (variable) | 862 +--------------------------------------------------+ 863 | Multicast Group Length (1 octet) | 864 +--------------------------------------------------+ 865 | Multicast Group Address (Variable) | 866 +--------------------------------------------------+ 867 | Originator Router Length (1 octet) | 868 +--------------------------------------------------+ 869 | Originator Router Address (variable) | 870 +--------------------------------------------------+ 871 | Flags (1 octet) | 872 +--------------------------------------------------+ 874 For the purpose of BGP route key processing, all the fields are 875 considered to be part of the prefix in the NLRI except for the one- 876 octet Flags field, whose fields are defined as follows: 878 0 1 2 3 4 5 6 7 879 +--+--+--+--+--+--+--+--+ 880 | reserved |IE|v3|v2|v1| 881 +--+--+--+--+--+--+--+--+ 883 o The least significant bit, bit 7 indicates support for IGMP 884 version 1. 886 o The second least significant bit, bit 6 indicates support for IGMP 887 version 2. 889 o The third least significant bit, bit 5 indicates support for IGMP 890 version 3. 892 o The fourth least significant bit, bit 4 indicates whether the (S, 893 G) information carried within the route-type is of Include Group 894 type (bit value 0) or an Exclude Group type (bit value 1). The 895 Exclude Group type bit MUST be ignored if bit 5 is not set. 897 o Reserved bits MUST be set to 0. They can be defined in future by 898 other document. 900 The Flags field assists in distributing IGMP Membership Report of a 901 given host/VM for a given multicast route. The version bits help 902 associate IGMP version of receivers participating within the EVPN 903 domain. The include/exclude bit helps in creating filters for a 904 given multicast route. 906 If route is being prepared for IPv6 (MLD) then bit 7 indicates 907 support for MLD version 1. The second least significant bit, bit 6 908 indicates support for MLD version 2. Since there is no MLD version 909 3, in case of IPv6 route third least significant bit MUST be 0. In 910 case of IPv6 route, the fourth least significant bit MUST be ignored 911 if bit 6 is not set. 913 9.2.1. Constructing the Multicast Join Synch Route 915 This section describes the procedures used to construct the IGMP Join 916 Synch route. Support for these route types is optional. If a PE 917 does not support this route, then it MUST NOT indicate that it 918 supports 'IGMP proxy' in the Multicast Flag extended community for 919 the EVIs corresponding to its multi-homed Ethernet Segments (ESs). 921 An IGMP Join Synch route MUST carry exactly one ES-Import Route 922 Target extended community, the one that corresponds to the ES on 923 which the IGMP Join was received. It MUST also carry exactly one 924 EVI-RT EC, the one that corresponds to the EVI on which the IGMP Join 925 was received. See Section 9.5 for details on how to encode and 926 construct the EVI-RT EC. 928 The Route Distinguisher (RD) SHOULD be a Type 1 RD [RFC4364]. The 929 value field comprises an IP address of the PE (typically, the 930 loopback address) followed by a number unique to the PE. 932 The Ethernet Segment Identifier (ESI) MUST be set to the 10-octet 933 value defined for the ES. 935 The Ethernet Tag ID MUST be set as per procedure defined in 936 [RFC7432]. 938 The Multicast Source length MUST be set to length of Multicast Source 939 address in bits. If the Multicast Source field contains an IPv4 940 address, then the value of the Multicast Source Length field is 32. 941 If the Multicast Source field contains an IPv6 address, then the 942 value of the Multicast Source Length field is 128. In case of a 943 (*,G) Join, the Multicast Source Length is set to 0. 945 The Multicast Source is the Source IP address of the IGMP Membership 946 Report. In case of a (*,G) Join, this field does not exist. 948 The Multicast Group length MUST be set to length of multicast group 949 address in bits. If the Multicast Group field contains an IPv4 950 address, then the value of the Multicast Group Length field is 32. 951 If the Multicast Group field contains an IPv6 address, then the value 952 of the Multicast Group Length field is 128. 954 The Multicast Group is the Group address of the IGMP Membership 955 Report. 957 The Originator Router Length is the length of the Originator Router 958 address in bits. 960 The Originator Router Address is the IP address of Router Originating 961 the prefix. 963 The Flags field indicates the version of IGMP protocol from which the 964 Membership Report was received. It also indicates whether the 965 multicast group had INCLUDE or EXCLUDE bit set. 967 Reserved bits MUST be set to 0. They can be defined in future by 968 other document. 970 9.3. Multicast Leave Synch Route 972 This EVPN route type is used to coordinate IGMP Leave Group (x,G) 973 state for a given BD between the PEs attached to a given ES operating 974 in All-Active (or Single-Active) redundancy mode and it consists of 975 following: 977 +--------------------------------------------------+ 978 | RD (8 octets) | 979 +--------------------------------------------------+ 980 | Ethernet Segment Identifier (10 octets) | 981 +--------------------------------------------------+ 982 | Ethernet Tag ID (4 octets) | 983 +--------------------------------------------------+ 984 | Multicast Source Length (1 octet) | 985 +--------------------------------------------------+ 986 | Multicast Source Address (variable) | 987 +--------------------------------------------------+ 988 | Multicast Group Length (1 octet) | 989 +--------------------------------------------------+ 990 | Multicast Group Address (Variable) | 991 +--------------------------------------------------+ 992 | Originator Router Length (1 octet) | 993 +--------------------------------------------------+ 994 | Originator Router Address (variable) | 995 +--------------------------------------------------+ 996 | Reserved (4 octet) | 997 +--------------------------------------------------+ 998 | Maximum Response Time (1 octet) | 999 +--------------------------------------------------+ 1000 | Flags (1 octet) | 1001 +--------------------------------------------------+ 1003 For the purpose of BGP route key processing, all the fields are 1004 considered to be part of the prefix in the NLRI except for the 1005 Reserved, Maximum Response Time and the one-octet Flags field, whose 1006 fields are defined as follows: 1008 0 1 2 3 4 5 6 7 1009 +--+--+--+--+--+--+--+--+ 1010 | reserved |IE|v3|v2|v1| 1011 +--+--+--+--+--+--+--+--+ 1013 o The least significant bit, bit 7 indicates support for IGMP 1014 version 1. 1016 o The second least significant bit, bit 6 indicates support for IGMP 1017 version 2. 1019 o The third least significant bit, bit 5 indicates support for IGMP 1020 version 3. 1022 o The fourth least significant bit, bit 4 indicates whether the (S, 1023 G) information carried within the route-type is of Include Group 1024 type (bit value 0) or an Exclude Group type (bit value 1). The 1025 Exclude Group type bit MUST be ignored if bit 5 is not set. 1027 o Reserved bits MUST be set to 0. They can be defined in future by 1028 other document. 1030 The Flags field assists in distributing IGMP Membership Report of a 1031 given host/VM for a given multicast route. The version bits help 1032 associate IGMP version of receivers participating within the EVPN 1033 domain. The include/exclude bit helps in creating filters for a 1034 given multicast route. 1036 If route is being prepared for IPv6 (MLD) then bit 7 indicates 1037 support for MLD version 1. The second least significant bit, bit 6 1038 indicates support for MLD version 2. Since there is no MLD version 1039 3, in case of IPv6 route third least significant bit MUST be 0. In 1040 case of IPv6 route, the fourth least significant bit MUST be ignored 1041 if bit 6 is not set. 1043 Reserved bits in flag MUST be set to 0. They can be defined in 1044 future by other document. 1046 9.3.1. Constructing the Multicast Leave Synch Route 1048 This section describes the procedures used to construct the IGMP 1049 Leave Synch route. Support for these route types is optional. If a 1050 PE does not support this route, then it MUST NOT indicate that it 1051 supports 'IGMP proxy' in Multicast Flag extended community for the 1052 EVIs corresponding to its multi-homed Ethernet Segments. 1054 An IGMP Leave Synch route MUST carry exactly one ES-Import Route 1055 Target extended community, the one that corresponds to the ES on 1056 which the IGMP Leave was received. It MUST also carry exactly one 1057 EVI-RT EC, the one that corresponds to the EVI on which the IGMP 1058 Leave was received. See Section 9.5 for details on how to form the 1059 EVI-RT EC. 1061 The Route Distinguisher (RD) SHOULD be a Type 1 RD [RFC4364]. The 1062 value field comprises an IP address of the PE (typically, the 1063 loopback address) followed by a number unique to the PE. 1065 The Ethernet Segment Identifier (ESI) MUST be set to the 10-octet 1066 value defined for the ES. 1068 The Ethernet Tag ID MUST be set as per procedure defined in 1069 [RFC7432]. 1071 The Multicast Source length MUST be set to length of multicast source 1072 address in bits. If the Multicast Source field contains an IPv4 1073 address, then the value of the Multicast Source Length field is 32. 1074 If the Multicast Source field contains an IPv6 address, then the 1075 value of the Multicast Source Length field is 128. In case of a 1076 (*,G) Join, the Multicast Source Length is set to 0. 1078 The Multicast Source is the Source IP address of the IGMP Membership 1079 Report. In case of a (*,G) Join, this field does not exist. 1081 The Multicast Group length MUST be set to length of multicast group 1082 address in bits. If the Multicast Group field contains an IPv4 1083 address, then the value of the Multicast Group Length field is 32. 1084 If the Multicast Group field contains an IPv6 address, then the value 1085 of the Multicast Group Length field is 128. 1087 The Multicast Group is the Group address of the IGMP Membership 1088 Report. 1090 The Originator Router Length is the length of the Originator Router 1091 address in bits. 1093 The Originator Router Address is the IP address of Router Originating 1094 the prefix. 1096 Reserved field is not part of the route key. The originator MUST set 1097 the reserved field to Zero , the receiver SHOULD ignore it and if it 1098 needs to be propagated, it MUST propagate it unchanged 1100 Maximum Response Time is value to be used while sending query as 1101 defined in [RFC2236] 1103 The Flags field indicates the version of IGMP protocol from which the 1104 Membership Report was received. It also indicates whether the 1105 multicast group had INCLUDE or EXCLUDE bit set. 1107 9.4. Multicast Flags Extended Community 1109 The 'Multicast Flags' extended community is a new EVPN extended 1110 community. EVPN extended communities are transitive extended 1111 communities with a Type field value of 6. IANA will assign a Sub- 1112 Type from the 'EVPN Extended Community Sub-Types' registry. 1114 A PE that supports IGMP proxy on a given BD MUST attach this extended 1115 community to the Inclusive Multicast Ethernet Tag (IMET) route it 1116 advertises for that BD and it MUST set the IGMP Proxy Support flag to 1117 1. Note that an [RFC7432] compliant PE will not advertise this 1118 extended community so its absence indicates that the advertising PE 1119 does not support IGMP Proxy. 1121 The advertisement of this extended community enables more efficient 1122 multicast tunnel setup from the source PE specially for ingress 1123 replication - i.e., if an egress PE supports IGMP proxy but doesn't 1124 have any interest in a given (x,G), it advertises its IGMP proxy 1125 capability using this extended community but it does not advertise 1126 any SMET route for that (x,G). When the source PE (ingress PE) 1127 receives such advertisements from the egress PE, it does not 1128 replicate the multicast traffic to that egress PE; however, it does 1129 replicate the multicast traffic to the egress PEs that don't 1130 advertise such capability even if they don't have any interests in 1131 that (x,G). 1133 A Multicast Flags extended community is encoded as an 8-octet value, 1134 as follows: 1136 0 1 2 3 1137 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 1138 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1139 | Type=0x06 | Sub-Type=0x09| Flags (2 Octets) |M|I| 1140 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1141 | Reserved=0 | 1142 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1144 The low-order (lease significant) two bits are defined as the "IGMP 1145 Proxy Support and MLD Proxy Support" bit. The absence of this 1146 extended community also means that the PE does not support IGMP 1147 proxy. where: 1149 o Type is 0x06 as registered with IANA for EVPN Extended 1150 Communities. 1152 o Sub-Type : 0x09 1154 o Flags are two Octets value. 1156 * Bit 15 (shown as I) defines IGMP Proxy Support. Value of 1 for 1157 bit 15 means that PE supports IGMP Proxy. Value of 0 for bit 1158 15 means that PE does not supports IGMP Proxy. 1160 * Bit 14 (shown as M) defines MLD Proxy Support. Value of 1 for 1161 bit 14 means that PE supports MLD Proxy. Value of 0 for bit 14 1162 means that PE does not support MLD proxy. 1164 * Bit 0 to 13 are reserved for future. Sender MUST set it 0 and 1165 receiver MUST ignore it. 1167 o Reserved bits are set to 0. Sender MUST set it to 0 and receiver 1168 MUST ignore it. 1170 If a router does not support this specification, it MUST NOT add 1171 Multicast Flags Extended Community in BGP route. A router receiving 1172 BGP update, if M and I both flag are zero (0), the router MUST treat 1173 this Update as malformed. Receiver of such update MUST ignore the 1174 extended community. 1176 9.5. EVI-RT Extended Community 1178 In EVPN, every EVI is associated with one or more Route Targets 1179 (RTs). These Route Targets serve two functions: 1181 1. Distribution control: RTs control the distribution of the routes. 1182 If a route carries the RT associated with a particular EVI, it 1183 will be distributed to all the PEs on which that EVI exists. 1185 2. EVI identification: Once a route has been received by a 1186 particular PE, the RT is used to identify the EVI to which it 1187 applies. 1189 An IGMP Join Synch or IGMP Leave Synch route is associated with a 1190 particular combination of ES and EVI. These routes need to be 1191 distributed only to PEs that are attached to the associated ES. 1192 Therefore these routes carry the ES-Import RT for that ES. 1194 Since an IGMP Join Synch or IGMP Leave Synch route does not need to 1195 be distributed to all the PEs on which the associated EVI exists, 1196 these routes cannot carry the RT associated with that EVI. 1197 Therefore, when such a route arrives at a particular PE, the route's 1198 RTs cannot be used to identify the EVI to which the route applies. 1199 Some other means of associating the route with an EVI must be used. 1201 This document specifies four new Extended Communities (EC) that can 1202 be used to identify the EVI with which a route is associated, but 1203 which do not have any effect on the distribution of the route. These 1204 new ECs are known as the "Type 0 EVI-RT EC", the "Type 1 EVI-RT EC", 1205 the "Type 2 EVI-RT EC", and the "Type 3 EVI-RT EC". 1207 1. A Type 0 EVI-RT EC is an EVPN EC (type 6) of sub-type 0xA. 1209 2. A Type 1 EVI-RT EC is an EVPN EC (type 6) of sub-type 0xB. 1211 3. A Type 2 EVI-RT EC is an EVPN EC (type 6) of sub-type 0xC. 1213 4. A Type 3 EVI-RT EC is an EVPN EC (type 6) of sub-type 0xD 1215 Each IGMP Join Synch or IGMP Leave Synch route MUST carry exactly one 1216 EVI-RT EC. The EVI-RT EC carried by a particular route is 1217 constructed as follows. Each such route is the result of having 1218 received an IGMP Join or an IGMP Leave message from a particular BD. 1219 The route is said to be associated associated with that BD. For each 1220 BD, there is a corresponding RT that is used to ensure that routes 1221 "about" that BD are distributed to all PEs attached to that BD. So 1222 suppose a given IGMP Join Synch or Leave Synch route is associated 1223 with a given BD, say BD1, and suppose that the corresponding RT for 1224 BD1 is RT1. Then: 1226 o 0. If RT1 is a Transitive Two-Octet AS-specific EC, then the EVI- 1227 RT EC carried by the route is a Type 0 EVI-RT EC. The value field 1228 of the Type 0 EVI-RT EC is identical to the value field of RT1. 1230 o 1. If RT1 is a Transitive IPv4-Address-specific EC, then the EVI- 1231 RT EC carried by the route is a Type 1 EVI-RT EC. The value field 1232 of the Type 1 EVI-RT EC is identical to the value field of RT1. 1234 o 2. If RT1 is a Transitive Four-Octet-specific EC, then the EVI-RT 1235 EC carried by the route is a Type 2 EVI-RT EC. The value field of 1236 the Type 2 EVI-RT EC is identical to the value field of RT1. 1238 o 3. If RT1 is a Transitive IPv6-Address-specific EC, then the EVI- 1239 RT EC carried by the route is a Type 3 EVI-RT EC. The value field 1240 of the Type 3 EVI-RT EC is identical to the value field of RT1. 1242 An IGMP Join Synch or Leave Synch route MUST carry exactly one EVI-RT 1243 EC. 1245 Suppose a PE receives a particular IGMP Join Synch or IGMP Leave 1246 Synch route, say R1, and suppose that R1 carries an ES-Import RT that 1247 is one of the PE's Import RTs. If R1 has no EVI-RT EC, or has more 1248 than one EVI-RT EC, the PE MUST apply the "treat-as-withdraw" 1249 procedure of [RFC7606]. 1251 Note that an EVI-RT EC is not a Route Target Extended Community, is 1252 not visible to the RT Constrain mechanism [RFC4684], and is not 1253 intended to influence the propagation of routes by BGP. 1255 1 2 3 1256 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 1257 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1258 | Type=0x06 | Sub-Type=n | RT associated with EVI | 1259 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1260 | RT associated with the EVI (cont.) | 1261 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1263 Where the value of 'n' is 0x0A, 0x0B, 0x0C, or 0x0D corresponding to 1264 EVI-RT type 0, 1, 2, or 3 respectively. 1266 9.6. Rewriting of RT ECs and EVI-RT ECs by ASBRs 1268 There are certain situations in which an ES is attached to a set of 1269 PEs that are not all in the same AS, or not all operated by the same 1270 provider. In some such situations, the RT that corresponds to a 1271 particular EVI may be different in each AS. If a route is propagated 1272 from AS1 to AS2, an ASBR at the AS1/AS2 border may be provisioned 1273 with a policy that removes the RTs that are meaningful in AS1 and 1274 replaces them with the corresponding (i.e., RTs corresponding to the 1275 same EVIs) RTs that are meaningful in AS2. This is known as RT- 1276 rewriting. 1278 Note that if a given route's RTs are rewritten, and the route carries 1279 an EVI-RT EC, the EVI-RT EC needs to be rewritten as well. 1281 9.7. BGP Error Handling 1283 If a received BGP update contains Flags not in accordance with IGMP/ 1284 MLD version-X expectation, the PE MUST apply the "treat-as-withdraw" 1285 procedure as per [RFC7606] 1287 If a received BGP update is malformed such that BGP route keys cannot 1288 be extracted, then BGP update MUST be considered as invalid. 1289 Receiving PE MUST apply the "Session reset" procedure of [RFC7606]. 1291 10. IGMP/MLD Immediate Leave 1293 IGMP MAY be configured with immediate leave option. This allows the 1294 device to remove the group entry from the multicast routing table 1295 immediately upon receiving a IGMP leave message for (x,G). In case 1296 of all active multi-homing while synchronizing the IGMP Leave state 1297 to redundancy peers, Maximum Response Time MAY be filled in as Zero. 1298 Implementations SHOULD have identical configuration across multi- 1299 homed peers. In case IGMP Leave Synch route is received with Maximum 1300 Response Time Zero, irrespective of local IGMP configuration it MAY 1301 be processed as an immediate leave. 1303 11. IGMP Version 1 Membership Report 1305 This document does not provide any detail about IGMPv1 processing. 1306 Multicast working group are in process of deprecating uses of IGMPv1. 1307 Implementations MUST only use IGMPv2 and above for IPv4 and MLDv1 and 1308 above for IPv6. IGMP V1 routes MUST be considered as invalid and the 1309 PE MUST apply the "treat-as-withdraw" procedure as per [RFC7606]. 1310 Initial version of draft did mention use of IGMPv1 and flag had 1311 provision to support IGMPv1. There may be an implemention which is 1312 deployed as initial version of draft, to interop flag has not been 1313 changed. 1315 12. Security Considerations 1317 Same security considerations as [RFC7432], [RFC2236], [RFC3376], 1318 [RFC2710], [RFC3810]. 1320 13. IANA Considerations 1322 IANA has allocated the following codepoints from the EVPN Extended 1323 Community sub-types registry. 1325 0x09 Multicast Flags Extended Community [this document] 1326 0x0A EVI-RT Type 0 [this document] 1327 0x0B EVI-RT Type 1 [this document] 1328 0x0C EVI-RT Type 2 [this document] 1330 IANA is requested to allocate a new codepoint from the EVPN Extended 1331 Community sub-types registry for the following. 1333 0x0D EVI-RT Type 3 [this document] 1335 IANA has allocated the following EVPN route types from the EVPN Route 1336 Type registry. 1338 6 - Selective Multicast Ethernet Tag Route 1339 7 - Multicast Join Synch Route 1340 8 - Multicast Leave Synch Route 1342 The Multicast Flags Extended Community contains a 16-bit Flags field. 1343 The bits are numbered 0-15, from high-order to low-order. 1345 The registry should be initialized as follows: 1346 Bit Name Reference 1347 ---- -------------- ------------- 1348 0 - 13 Unassigned 1349 14 MLD Proxy Support This document 1350 15 IGMP Proxy Support This document 1352 The registration policy should be "First Come First Served". 1354 14. Acknowledgement 1356 The authors would like to thank Stephane Litkowski, Jorge Rabadan, 1357 Anoop Ghanwani, Jeffrey Haas, Krishna Muddenahally Ananthamurthy, 1358 Swadesh Agrawal for reviewing and providing valuable comment. 1360 15. Contributors 1362 Derek Yeung 1364 Arrcus 1366 Email: derek@arrcus.com 1368 16. References 1370 16.1. Normative References 1372 [I-D.ietf-bess-evpn-bum-procedure-updates] 1373 Zhang, Z., Lin, W., Rabadan, J., Patel, K., and A. 1374 Sajassi, "Updates on EVPN BUM Procedures", draft-ietf- 1375 bess-evpn-bum-procedure-updates-08 (work in progress), 1376 November 2019. 1378 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1379 Requirement Levels", BCP 14, RFC 2119, 1380 DOI 10.17487/RFC2119, March 1997, 1381 . 1383 [RFC2236] Fenner, W., "Internet Group Management Protocol, Version 1384 2", RFC 2236, DOI 10.17487/RFC2236, November 1997, 1385 . 1387 [RFC2710] Deering, S., Fenner, W., and B. Haberman, "Multicast 1388 Listener Discovery (MLD) for IPv6", RFC 2710, 1389 DOI 10.17487/RFC2710, October 1999, 1390 . 1392 [RFC3376] Cain, B., Deering, S., Kouvelas, I., Fenner, B., and A. 1393 Thyagarajan, "Internet Group Management Protocol, Version 1394 3", RFC 3376, DOI 10.17487/RFC3376, October 2002, 1395 . 1397 [RFC3810] Vida, R., Ed. and L. Costa, Ed., "Multicast Listener 1398 Discovery Version 2 (MLDv2) for IPv6", RFC 3810, 1399 DOI 10.17487/RFC3810, June 2004, 1400 . 1402 [RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private 1403 Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February 1404 2006, . 1406 [RFC4684] Marques, P., Bonica, R., Fang, L., Martini, L., Raszuk, 1407 R., Patel, K., and J. Guichard, "Constrained Route 1408 Distribution for Border Gateway Protocol/MultiProtocol 1409 Label Switching (BGP/MPLS) Internet Protocol (IP) Virtual 1410 Private Networks (VPNs)", RFC 4684, DOI 10.17487/RFC4684, 1411 November 2006, . 1413 [RFC6625] Rosen, E., Ed., Rekhter, Y., Ed., Hendrickx, W., and R. 1414 Qiu, "Wildcards in Multicast VPN Auto-Discovery Routes", 1415 RFC 6625, DOI 10.17487/RFC6625, May 2012, 1416 . 1418 [RFC7432] Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A., 1419 Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based 1420 Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432, February 1421 2015, . 1423 [RFC7606] Chen, E., Ed., Scudder, J., Ed., Mohapatra, P., and K. 1424 Patel, "Revised Error Handling for BGP UPDATE Messages", 1425 RFC 7606, DOI 10.17487/RFC7606, August 2015, 1426 . 1428 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1429 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1430 May 2017, . 1432 16.2. Informative References 1434 [RFC4541] Christensen, M., Kimball, K., and F. Solensky, 1435 "Considerations for Internet Group Management Protocol 1436 (IGMP) and Multicast Listener Discovery (MLD) Snooping 1437 Switches", RFC 4541, DOI 10.17487/RFC4541, May 2006, 1438 . 1440 Authors' Addresses 1442 Ali Sajassi 1443 Cisco Systems 1444 821 Alder Drive, 1445 MILPITAS, CALIFORNIA 95035 1446 UNITED STATES 1448 Email: sajassi@cisco.com 1450 Samir Thoria 1451 Cisco Systems 1452 821 Alder Drive, 1453 MILPITAS, CALIFORNIA 95035 1454 UNITED STATES 1456 Email: sthoria@cisco.com 1458 Mankamana Mishra 1459 Cisco Systems 1460 821 Alder Drive, 1461 MILPITAS, CALIFORNIA 95035 1462 UNITED STATES 1464 Email: mankamis@cisco.com 1466 Keyur PAtel 1467 Arrcus 1468 UNITED STATES 1470 Email: keyur@arrcus.com 1472 John Drake 1473 Juniper Networks 1475 Email: jdrake@juniper.net 1476 Wen Lin 1477 Juniper Networks 1479 Email: wlin@juniper.net