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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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-14) exists of draft-ietf-bess-evpn-bum-procedure-updates-08 Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 1 comment (--).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: February 24, 2022 Cisco Systems 6 K. Patel 7 Arrcus 8 J. Drake 9 W. Lin 10 Juniper Networks 11 August 23, 2021 13 IGMP and MLD Proxy for EVPN 14 draft-ietf-bess-evpn-igmp-mld-proxy-12 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 February 24, 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 . . . . . . . . . . . . . . . . . . . . . . . . 16 88 9.1.2. Default Selective Multicast Route . . . . . . . . . . 18 89 9.2. Multicast Join Synch Route . . . . . . . . . . . . . . . 18 90 9.2.1. Constructing the Multicast Join Synch Route . . . . . 20 91 9.3. Multicast Leave Synch Route . . . . . . . . . . . . . . . 21 92 9.3.1. Constructing the Multicast Leave Synch Route . . . . 23 94 9.4. Multicast Flags Extended Community . . . . . . . . . . . 24 95 9.5. EVI-RT Extended Community . . . . . . . . . . . . . . . . 26 96 9.6. Rewriting of RT ECs and EVI-RT ECs by ASBRs . . . . . . . 28 97 9.7. BGP Error Handling . . . . . . . . . . . . . . . . . . . 28 98 10. IGMP/MLD Immediate Leave . . . . . . . . . . . . . . . . . . 28 99 11. IGMP Version 1 Membership Report . . . . . . . . . . . . . . 29 100 12. Security Considerations . . . . . . . . . . . . . . . . . . . 29 101 13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29 102 14. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 30 103 15. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 30 104 16. References . . . . . . . . . . . . . . . . . . . . . . . . . 30 105 16.1. Normative References . . . . . . . . . . . . . . . . . . 30 106 16.2. Informative References . . . . . . . . . . . . . . . . . 32 107 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 32 109 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 for multicast. It can be physical 236 interface, virtual interface or tunnel. 238 This document also assumes familiarity with the terminology of 239 [RFC7432]. Though most of the place this document uses term IGMP 240 Membership Report (Joins), the text applies equally for MLD 241 Membership Report too. Similarly, text for IGMPv2 applies to MLDv1 242 and text for IGMPv3 applies to MLDv2. IGMP / MLD version encoding in 243 BGP update is stated in Section 9 245 4. IGMP/MLD Proxy 247 The IGMP Proxy mechanism is used to reduce the flooding of IGMP 248 messages over an EVPN network similar to ARP proxy used in reducing 249 the flooding of ARP messages over EVPN. It also provides a 250 triggering mechanism for the PEs to setup their underlay multicast 251 tunnels. The IGMP Proxy mechanism consists of two components: 253 1. Proxy for IGMP Reports. 255 2. Proxy for IGMP Queries. 257 4.1. Proxy Reporting 259 When IGMP protocol is used between hosts/VMs and their first hop EVPN 260 router (EVPN PE), Proxy-reporting is used by the EVPN PE to summarize 261 (when possible) reports received from downstream hosts and propagate 262 them in BGP to other PEs that are interested in the information. 263 This is done by terminating the IGMP Reports in the first hop PE, and 264 translating and exchanging the relevant information among EVPN BGP 265 speakers. The information is again translated back to IGMP message 266 at the recipient EVPN speaker. Thus it helps create an IGMP overlay 267 subnet using BGP. In order to facilitate such an overlay, this 268 document also defines a new EVPN route type NLRI, the EVPN Selective 269 Multicast Ethernet Tag route, along with its procedures to help 270 exchange and register IGMP multicast groups Section 9. 272 4.1.1. IGMP/MLD Membership Report Advertisement in BGP 274 When a PE wants to advertise an IGMP Membership Report (Join) using 275 the BGP EVPN route, it follows the following rules (BGP encoding 276 stated in Section 9): 278 1. When the first hop PE receives several IGMP Membership Reports 279 (Joins), belonging to the same IGMP version, from different 280 attached hosts/VMs for the same (*,G) or (S,G), it SHOULD send a 281 single BGP message corresponding to the very first IGMP 282 Membership Request (BGP update as soon as possible) for that 283 (*,G) or (S,G). This is because BGP is a stateful protocol and 284 no further transmission of the same report is needed. If the 285 IGMP Membership Request is for (*,G), then multicast group 286 address MUST be sent along with the corresponding version flag 287 (v2 or v3) set. In case of IGMPv3, the exclude flag MUST also be 288 set to indicate that no source IP address must be excluded 289 (include all sources"*"). If the IGMP Join is for (S,G), then 290 besides setting multicast group address along with the version 291 flag v3, the source IP address and the IE flag MUST be set. It 292 should be noted that when advertising the EVPN route for (S,G), 293 the only valid version flag is v3 (v2 flags MUST be set to zero). 295 2. When the first hop PE receives an IGMPv3 Join for (S,G) on a 296 given BD, it SHOULD advertise the corresponding EVPN Selective 297 Multicast Ethernet Tag (SMET) route regardless of whether the 298 source (S) is attached to itself or not in order to facilitate 299 the source move in the future. 301 3. When the first hop PE receives an IGMP version-X Join first for 302 (*,G) and then later it receives an IGMP version-Y Join for the 303 same (*,G), then it MUST re-advertise the same EVPN SMET route 304 with flag for version-Y set in addition to any previously-set 305 version flag(s). In other words, the first hop PE MUST NOT 306 withdraw the EVPN route before sending the new route because the 307 flag field is not part of BGP route key processing. 309 4. When the first hop PE receives an IGMP version-X Join first for 310 (*,G) and then later it receives an IGMPv3 Join for the same 311 multicast group address but for a specific source address S, then 312 the PE MUST advertise a new EVPN SMET route with v3 flag set (and 313 v2 reset). The IE flag also need to be set accordingly. Since 314 source IP address is used as part of BGP route key processing it 315 is considered as a new BGP route advertisement. When different 316 version of IGMP join are received, final state MUST be as per 317 section 5.1 of [RFC3376]. At the end of route processing local 318 and remote group record state MUST be as per section 5.1 of 319 [RFC3376]. 321 5. When a PE receives an EVPN SMET route with more than one version 322 flag set, it will generate the corresponding IGMP report for 323 (*,G) for each version specified in the flags field. With 324 multiple version flags set, there must not be source IP address 325 in the received EVPN route. If there is, then an error SHOULD be 326 logged. If the v3 flag is set (in addition to v2), then the IE 327 flag MUST indicate "exclude". If not, then an error SHOULD be 328 logged. The PE MUST generate an IGMP Membership Report (Join) 329 for that (*,G) and each IGMP version in the version flag. 331 6. When a PE receives a list of EVPN SMET NLRIs in its BGP update 332 message, each with a different source IP address and the same 333 multicast group address, and the version flag is set to v3, then 334 the PE generates an IGMPv3 Membership Report with a record 335 corresponding to the list of source IP addresses and the group 336 address along with the proper indication of inclusion/exclusion. 338 7. Upon receiving EVPN SMET route(s) and before generating the 339 corresponding IGMP Membership Request(s), the PE checks to see 340 whether it has any CE multicast router for that BD on any of its 341 ES's . The PE provides such a check by listening for PIM Hello 342 messages on that AC (i.e, ES,BD). If the PE does have the 343 router's ACs, then the generated IGMP Membership Request(s) are 344 sent to those ACs. If it doesn't have any of the router's AC, 345 then no IGMP Membership Request(s) needs to be generated. This 346 is because sending IGMP Membership Requests to other hosts can 347 result in unintentionally preventing a host from joining a 348 specific multicast group using IGMPv2 - i.e., if the PE does not 349 receive a join from the host it will not forward multicast data 350 to it. Per [RFC4541] , when an IGMPv2 host receives a Membership 351 Report for a group address that it intends to join, the host will 352 suppress its own membership report for the same group, and if the 353 PE does not receive an IGMP Join from host it will not forward 354 multicast data to it. In other words, an IGMPv2 Join MUST NOT be 355 sent on an AC that does not lead to a CE multicast router. This 356 message suppression is a requirement for IGMPv2 hosts. This is 357 not a problem for hosts running IGMPv3 because there is no 358 suppression of IGMP Membership Reports. 360 4.1.2. IGMP/MLD Leave Group Advertisement in BGP 362 When a PE wants to withdraw an EVPN SMET route corresponding to an 363 IGMPv2 Leave Group (Leave) or IGMPv3 "Leave" equivalent message, it 364 follows the following rules: 366 1. When a PE receives an IGMPv2 Leave Group or its "Leave" 367 equivalent message for IGMPv3 from its attached host, it checks 368 to see if this host is the last host that is interested in this 369 multicast group by sending a query for the multicast group. If 370 the host was indeed the last one (i.e. no responses are received 371 for the query), then the PE MUST re-advertises EVPN SMET 372 Multicast route with the corresponding version flag reset. If 373 this is the last version flag to be reset, then instead of re- 374 advertising the EVPN route with all version flags reset, the PE 375 MUST withdraw the EVPN route for that (*,G). 377 2. When a PE receives an EVPN SMET route for a given (*,G), it 378 compares the received version flags from the route with its per- 379 PE stored version flags. If the PE finds that a version flag 380 associated with the (*,G) for the remote PE is reset, then the PE 381 MUST generate IGMP Leave for that (*,G) toward its local 382 interface (if any) attached to the multicast router for that 383 multicast group. It should be noted that the received EVPN route 384 SHOULD at least have one version flag set. If all version flags 385 are reset, it is an error because the PE should have received an 386 EVPN route withdraw for the last version flag. Error MUST be 387 considered as BGP error and the PE MUST apply the "treat-as- 388 withdraw" procedure of [RFC7606]. 390 3. When a PE receives an EVPN SMET route withdraw, it removes the 391 remote PE from its OIF list for that multicast group and if there 392 are no more OIF entries for that multicast group (either locally 393 or remotely), then the PE MUST stop responding to queries from 394 the locally attached router (if any). If there is a source for 395 that multicast group, the PE stops sending multicast traffic for 396 that source. 398 4.2. Proxy Querier 400 As mentioned in the previous sections, each PE MUST have proxy 401 querier functionality for the following reasons: 403 1. To enable the collection of EVPN PEs providing L2VPN service to 404 act as distributed multicast router with Anycast IP address for 405 all attached hosts/VMs in that subnet. 407 2. To enable suppression of IGMP Membership Reports and queries over 408 MPLS/IP core. 410 5. Operation 412 Consider the EVPN network of Figure-1, where there is an EVPN 413 instance configured across the PEs shown in this figure (namely PE1, 414 PE2, and PE3). Let's consider that this EVPN instance consists of a 415 single bridge domain (single subnet) with all the hosts, sources, and 416 the multicast router connected to this subnet. PE1 only has hosts 417 connected to it. PE2 has a mix of hosts and a multicast source. PE3 418 has a mix of hosts, a multicast source, and a multicast router. 419 Furthermore, let's consider that for (S1,G1), R1 is used as the 420 multicast router. The following subsections describe the IGMP proxy 421 operation in different PEs with regard to whether the locally 422 attached devices for that subnet are: 424 o only hosts/VMs 426 o mix of hosts/VMs and multicast source 428 o mix of hosts/VMs, multicast source, and multicast router 429 +--------------+ 430 | | 431 | | 432 +----+ | | +----+ 433 H1:(*,G1)v2 ---| | | | | |---- H6(*,G1)v2 434 H2:(*,G1)v2 ---| PE1| | IP/MPLS | | PE2|---- H7(S2,G2)v3 435 H3:(*,G1)v3 ---| | | Network | | |---- S2 436 H4:(S2,G2)v3 --| | | | | | 437 +----+ | | +----+ 438 | | 439 +----+ | | 440 H5:(S1,G1)v3 --| | | | 441 S1 ---| PE3| | | 442 R1 ---| | | | 443 +----+ | | 444 | | 445 +--------------+ 447 Figure 1: EVPN network 449 5.1. PE with only attached hosts/VMs for a given subnet 451 When PE1 receives an IGMPv2 Membership Report from H1, it does not 452 forward this join to any of its other ports (for this subnet) because 453 all these local ports are associated with the hosts/VMs. PE1 sends 454 an EVPN Multicast Group route corresponding to this join for (*,G1) 455 and setting v2 flag. This EVPN route is received by PE2 and PE3 that 456 are the members of the same BD (i.e., same EVI in case of VLAN-based 457 service or EVI,VLAN in case of VLAN-aware bundle service). PE3 458 reconstructs the IGMPv2 Membership Report from this EVPN BGP route 459 and only sends it to the port(s) with multicast routers attached to 460 it (for that subnet). In this example, PE3 sends the reconstructed 461 IGMPv2 Membership Report for (*,G1) only to R1. Furthermore, even 462 though PE2 receives the EVPN BGP route, it does not send it to any of 463 its ports for that subnet; viz, ports associated with H6 and H7. 465 When PE1 receives the second IGMPv2 Join from H2 for the same 466 multicast group (*,G1), it only adds that port to its OIF list but it 467 doesn't send any EVPN BGP route because there is no change in 468 information. However, when it receives the IGMPv3 Join from H3 for 469 the same (*,G1). Besides adding the corresponding port to its OIF 470 list, it re-advertises the previously sent EVPN SMET route with the 471 v3 and exclude flag set. 473 Finally when PE1 receives the IGMPv3 Join from H4 for (S2,G2), it 474 advertises a new EVPN SMET route corresponding to it. 476 5.2. PE with a mix of attached hosts/VMs and multicast source 478 The main difference in this case is that when PE2 receives the IGMPv3 479 Join from H7 for (S2,G2), it does advertise it in BGP to support 480 source move even though PE2 knows that S2 is attached to its local 481 AC. PE2 adds the port associated with H7 to its OIF list for 482 (S2,G2). The processing for IGMPv2 received from H6 is the same as 483 the IGMPv2 Join described in previous section. 485 5.3. PE with a mix of attached hosts/VMs, a multicast source and a 486 router 488 The main difference in this case relative to the previous two 489 sections is that IGMP v2/v3 Join messages received locally need to be 490 sent to the port associated with router R1. Furthermore, the Joins 491 received via BGP (SMET) need to be passed to the R1 port but filtered 492 for all other ports. 494 6. All-Active Multi-Homing 496 Because the LAG flow hashing algorithm used by the CE is unknown at 497 the PE, in an All-Active redundancy mode it must be assumed that the 498 CE can send a given IGMP message to any one of the multi-homed PEs, 499 either DF or non-DF; i.e., different IGMP Membership Request messages 500 can arrive at different PEs in the redundancy group and furthermore 501 their corresponding Leave messages can arrive at PEs that are 502 different from the ones that received the Join messages. Therefore, 503 all PEs attached to a given ES must coordinate IGMP Membership 504 Request and Leave Group (x,G) state, where x may be either '*' or a 505 particular source S, for each BD on that ES. This allows the DF for 506 that (ES,BD) to correctly advertise or withdraw a Selective Multicast 507 Ethernet Tag (SMET) route for that (x,G) group in that BD when 508 needed. All-Active multihoming PEs for a given ES MUST support IGMP 509 synchronization procedures described in this section if they need to 510 perform IGMP proxy for hosts connected to that ES. 512 6.1. Local IGMP/MLD Join Synchronization 514 When a PE, either DF or non-DF, receives on a given multihomed ES 515 operating in All-Active redundancy mode, an IGMP Membership Report 516 for (x,G), it determines the BD to which the IGMP Membership Report 517 belongs. If the PE doesn't already have local IGMP Membership 518 Request (x,G) state for that BD on that ES, it MUST instantiate local 519 IGMP Membership Request (x,G) state and MUST advertise a BGP IGMP 520 Join Synch route for that (ES,BD). Local IGMP Membership Request 521 (x,G) state refers to IGMP Membership Request (x,G) state that is 522 created as a result of processing an IGMP Membership Report for 523 (x,G). 525 The IGMP Join Synch route MUST carry the ES-Import RT for the ES on 526 which the IGMP Membership Report was received. Thus it MUST only be 527 imported by the PEs attached to that ES and not any other PEs. 529 When a PE, either DF or non-DF, receives an IGMP Join Synch route it 530 installs that route and if it doesn't already have IGMP Membership 531 Request (x,G) state for that (ES,BD), it MUST instantiate that IGMP 532 Membership Request (x,G) state - i.e., IGMP Membership Request (x,G) 533 state is the union of the local IGMP Join (x,G) state and the 534 installed IGMP Join Synch route. If the DF did not already advertise 535 (originate) a SMET route for that (x,G) group in that BD, it MUST do 536 so now. 538 When a PE, either DF or non-DF, deletes its local IGMP Membership 539 Request (x,G) state for that (ES,BD), it MUST withdraw its BGP IGMP 540 Join Synch route for that (ES,BD). 542 When a PE, either DF or non-DF, receives the withdrawal of an IGMP 543 Join Synch route from another PE it MUST remove that route. When a 544 PE has no local IGMP Membership Request (x,G) state and it has no 545 installed IGMP Join Synch routes, it MUST remove IGMP Membership 546 Request (x,G) state for that (ES,BD). If the DF no longer has IGMP 547 Membership Request (x,G) state for that BD on any ES for which it is 548 DF, it MUST withdraw its SMET route for that (x,G) group in that BD. 550 In other words, a PE advertises an SMET route for that (x,G) group in 551 that BD when it has IGMP Membership Request (x,G) state in that BD on 552 at least one ES for which it is DF and it withdraws that SMET route 553 when it does not have IGMP Membership Request (x,G) state in that BD 554 on any ES for which it is DF. 556 6.2. Local IGMP/MLD Leave Group Synchronization 558 When a PE, either DF or non-DF, receives, on a given multihomed ES 559 operating in All-Active redundancy mode, an IGMP Leave Group message 560 for (x,G) from the attached CE, it determines the BD to which the 561 IGMPv2 Leave Group belongs. Regardless of whether it has IGMP 562 Membership Request (x,G) state for that (ES,BD), it initiates the 563 (x,G) leave group synchronization procedure, which consists of the 564 following steps: 566 1. It computes the Maximum Response Time, which is the duration of 567 (x,G) leave group synchronization procedure. This is the product 568 of two locally configured values, Last Member Query Count and 569 Last Member Query Interval (described in Section 3 of [RFC2236]), 570 plus a delta corresponding to the time it takes for a BGP 571 advertisement to propagate between the PEs attached to the 572 multihomed ES (delta is a consistently configured value on all 573 PEs attached to the multihomed ES). 575 2. It starts the Maximum Response Time timer. Note that the receipt 576 of subsequent IGMP Leave Group messages or BGP Leave Synch routes 577 for (x,G) do not change the value of a currently running Maximum 578 Response Time timer and are ignored by the PE. 580 3. It initiates the Last Member Query procedure described in 581 Section 3 of [RFC2236]; viz, it sends a number of Group-Specific 582 Query (x,G) messages (Last Member Query Count) at a fixed 583 interval (Last Member Query Interval) to the attached CE. 585 4. It advertises an IGMP Leave Synch route for that that (ES,BD). 586 This route notifies the other multihomed PEs attached to the 587 given multihomed ES that it has initiated an (x,G) leave group 588 synchronization procedure; i.e., it carries the ES-Import RT for 589 the ES on which the IGMP Leave Group was received. It also 590 contains the Maximum Response Time. 592 5. When the Maximum Response Timer expires, the PE that has 593 advertised the IGMP Leave Synch route withdraws it. 595 6.2.1. Remote Leave Group Synchronization 597 When a PE, either DF or non-DF, receives an IGMP Leave Synch route it 598 installs that route and it starts a timer for (x,G) on the specified 599 (ES,BD) whose value is set to the Maximum Response Time in the 600 received IGMP Leave Synch route. Note that the receipt of subsequent 601 IGMPv2 Leave Group messages or BGP Leave Synch routes for (x,G) do 602 not change the value of a currently running Maximum Response Time 603 timer and are ignored by the PE. 605 6.2.2. Common Leave Group Synchronization 607 If a PE attached to the multihomed ES receives an IGMP Membership 608 Report for (x,G) before the Maximum Response Time timer expires, it 609 advertises a BGP IGMP Join Synch route for that (ES,BD). If it 610 doesn't already have local IGMP Membership Request (x,G) state for 611 that (ES,BD), it instantiates local IGMP Membership Request (x,G) 612 state. If the DF is not currently advertising (originating) a SMET 613 route for that (x,G) group in that BD, it does so now. 615 If a PE attached to the multihomed ES receives an IGMP Join Synch 616 route for (x,G) before the Maximum Response Time timer expires, it 617 installs that route and if it doesn't already have IGMP Membership 618 Request (x,G) state for that BD on that ES, it instantiates that IGMP 619 Membership Request (x,G) state. If the DF has not already advertised 620 (originated) a SMET route for that (x,G) group in that BD, it does so 621 now. 623 When the Maximum Response Timer expires a PE that has advertised an 624 IGMP Leave Synch route, withdraws it. Any PE attached to the 625 multihomed ES, that started the Maximum Response Time and has no 626 local IGMP Membership Request (x,G) state and no installed IGMP Join 627 Synch routes, it removes IGMP Membership Request (x,G) state for that 628 (ES,BD). If the DF no longer has IGMP Membership Request (x,G) state 629 for that BD on any ES for which it is DF, it withdraws its SMET route 630 for that (x,G) group in that BD. 632 6.3. Mass Withdraw of Multicast join Sync route in case of failure 634 A PE which has received an IGMP Membership Request, would have synced 635 the IGMP Join by the procedure defined in section 6.1. If a PE with 636 local join state goes down or the PE to CE link goes down, it would 637 lead to a mass withdraw of multicast routes. Remote PEs (PEs where 638 these routes were remote IGMP Joins) SHOULD NOT remove the state 639 immediately; instead General Query SHOULD be generated to refresh the 640 states. There are several ways to detect failure at a peer, e.g. 641 using IGP next hop tracking or ES route withdraw. 643 7. Single-Active Multi-Homing 645 Note that to facilitate state synchronization after failover, the PEs 646 attached to a multihomed ES operating in Single-Active redundancy 647 mode SHOULD also coordinate IGMP Join (x,G) state. In this case all 648 IGMP Join messages are received by the DF and distributed to the non- 649 DF PEs using the procedures described above. 651 8. Selective Multicast Procedures for IR tunnels 653 If an ingress PE uses ingress replication, then for a given (x,G) 654 group in a given BD: 656 1. It sends (x,G) traffic to the set of PEs not supporting IGMP 657 Proxy. This set consists of any PE that has advertised an 658 Inclusive Multicast Tag route for the BD without the "IGMP Proxy 659 Support" flag. 661 2. It sends (x,G) traffic to the set of PEs supporting IGMP Proxy 662 and having listeners for that (x,G) group in that BD. This set 663 consists of any PE that has advertised an Inclusive Multicast 664 Ethernet Tag route for the BD with the "IGMP Proxy Support" flag 665 and that has advertised a SMET route for that (x,G) group in that 666 BD. 668 9. BGP Encoding 670 This document defines three new BGP EVPN routes to carry IGMP 671 Membership Reports. The route types are known as: 673 + 6 - Selective Multicast Ethernet Tag Route 675 + 7 - Multicast Join Synch Route 677 + 8 - Multicast Leave Synch Route 679 The detailed encoding and procedures for these route types are 680 described in subsequent sections. 682 9.1. Selective Multicast Ethernet Tag Route 684 A Selective Multicast Ethernet Tag route type specific EVPN NLRI 685 consists of the following: 687 +---------------------------------------+ 688 | RD (8 octets) | 689 +---------------------------------------+ 690 | Ethernet Tag ID (4 octets) | 691 +---------------------------------------+ 692 | Multicast Source Length (1 octet) | 693 +---------------------------------------+ 694 | Multicast Source Address (variable) | 695 +---------------------------------------+ 696 | Multicast Group Length (1 octet) | 697 +---------------------------------------+ 698 | Multicast Group Address (Variable) | 699 +---------------------------------------+ 700 | Originator Router Length (1 octet) | 701 +---------------------------------------+ 702 | Originator Router Address (variable) | 703 +---------------------------------------+ 704 | Flags (1 octet) | 705 +---------------------------------------+ 707 For the purpose of BGP route key processing, all the fields are 708 considered to be part of the prefix in the NLRI except for the one- 709 octet flag field. The Flags fields are defined as follows: 711 0 1 2 3 4 5 6 7 712 +--+--+--+--+--+--+--+--+ 713 | reserved |IE|v3|v2|v1| 714 +--+--+--+--+--+--+--+--+ 716 o The least significant bit, bit 7 indicates support for IGMP 717 version 1. Since IGMP V1 is being deprecated , sender MUST set it 718 as 0 for IGMP and receiver MUST ignore it. 720 o The second least significant bit, bit 6 indicates support for IGMP 721 version 2. 723 o The third least significant bit, bit 5 indicates support for IGMP 724 version 3. 726 o The fourth least significant bit, bit 4 indicates whether the 727 (S,G) information carried within the route-type is of an Include 728 Group type (bit value 0) or an Exclude Group type (bit value 1). 729 The Exclude Group type bit MUST be ignored if bit 5 is not set. 731 o This EVPN route type is used to carry tenant IGMP multicast group 732 information. The flag field assists in distributing IGMP 733 Membership Report of a given host/VM for a given multicast route. 734 The version bits help associate IGMP version of receivers 735 participating within the EVPN domain. 737 o The include/exclude bit helps in creating filters for a given 738 multicast route. 740 o If route is used for IPv6 (MLD) then bit 7 indicates support for 741 MLD version 1. The second least significant bit, bit 6 indicates 742 support for MLD version 2. Since there is no MLD version 3, in 743 case of IPv6 route third least significant bit MUST be 0. In case 744 of IPv6 routes, the fourth least significant bit MUST be ignored 745 if bit 6 is not set. 747 o Reserved bits SHOULD be set to 0 by sender. And receiver SHOULD 748 ignore the Reserved bits. 750 9.1.1. Constructing the Selective Multicast Ethernet Tag route 752 This section describes the procedures used to construct the Selective 753 Multicast Ethernet Tag (SMET) route. 755 The Route Distinguisher (RD) SHOULD be a Type 1 RD [RFC4364]. The 756 value field comprises an IP address of the PE (typically, the 757 loopback address) followed by a number unique to the PE. 759 The Ethernet Tag ID MUST be set as procedure defined in [RFC7432]. 761 The Multicast Source Length MUST be set to length of the multicast 762 Source address in bits. If the Multicast Source Address field 763 contains an IPv4 address, then the value of the Multicast Source 764 Length field is 32. If the Multicast Source Address field contains 765 an IPv6 address, then the value of the Multicast Source Length field 766 is 128. In case of a (*,G) Join, the Multicast Source Length is set 767 to 0. 769 The Multicast Source Address is the source IP address from the IGMP 770 Membership Report. In case of a (*,G), this field is not used. 772 The Multicast Group Length MUST be set to length of multicast group 773 address in bits. If the Multicast Group Address field contains an 774 IPv4 address, then the value of the Multicast Group Length field is 775 32. If the Multicast Group Address field contains an IPv6 address, 776 then the value of the Multicast Group Length field is 128. 778 The Multicast Group Address is the Group address from the IGMP or MLD 779 Membership Report. 781 The Originator Router Length is the length of the Originator Router 782 Address in bits. 784 The Originator Router Address is the IP address of router originating 785 this route. The SMET Originator Router IP address MUST match that of 786 the IMET (or S-PMSI AD) route originated for the same EVI by the same 787 downstream PE. 789 The Flags field indicates the version of IGMP protocol from which the 790 Membership Report was received. It also indicates whether the 791 multicast group had the INCLUDE or EXCLUDE bit set. 793 Reserved bits MUST be set to 0. They can be defined in future by 794 other document. 796 IGMP is used to receive group membership information from hosts/VMs 797 by TORs. Upon receiving the hosts/VMs expression of interest of a 798 particular group membership, this information is then forwarded using 799 SMET route. The NLRI also keeps track of receiver's IGMP protocol 800 version and any source filtering for a given group membership. All 801 EVPN SMET routes are announced with per- EVI Route Target extended 802 communities. 804 9.1.2. Default Selective Multicast Route 806 If there is multicast router connected behind the EVPN domain, the PE 807 MAY originate a default SMET (*,*) to get all multicast traffic in 808 domain. 810 +--------------+ 811 | | 812 | | 813 | | +----+ 814 | | | |---- H1(*,G1)v2 815 | IP/MPLS | | PE1|---- H2(S2,G2)v3 816 | Network | | |---- S2 817 | | | | 818 | | +----+ 819 | | 820 +----+ | | 821 +----+ | | | | 822 | | S1 ---| PE2| | | 823 |PIM |----R1 ---| | | | 824 |ASM | +----+ | | 825 | | | | 826 +----+ +--------------+ 828 Figure 2: Multicast Router behind EVPN domain 830 Consider the EVPN network of Figure-2, where there is an EVPN 831 instance configured across the PEs. Lets consider PE2 is connected 832 to multicast router R1 and there is a network running PIM ASM behind 833 R1. If there are receivers behind the PIM ASM network, the PIM Join 834 would be forwarded to the PIM RP (Rendezvous Point). If receivers 835 behind PIM ASM network are interested in a multicast flow originated 836 by multicast source S2 (behind PE1), it is necessary for PE2 to 837 receive multicast traffic. In this case PE2 MUST originate a (*,*) 838 SMET route to receive all of the multicast traffic in the EVPN 839 domain. To generate Wildcards (*,*) routes, prcedure from [RFC6625] 840 SHOULD be used. 842 9.2. Multicast Join Synch Route 844 This EVPN route type is used to coordinate IGMP Join (x,G) state for 845 a given BD between the PEs attached to a given ES operating in All- 846 Active (or Single-Active) redundancy mode and it consists of 847 following: 849 +--------------------------------------------------+ 850 | RD (8 octets) | 851 +--------------------------------------------------+ 852 | Ethernet Segment Identifier (10 octets) | 853 +--------------------------------------------------+ 854 | Ethernet Tag ID (4 octets) | 855 +--------------------------------------------------+ 856 | Multicast Source Length (1 octet) | 857 +--------------------------------------------------+ 858 | Multicast Source Address (variable) | 859 +--------------------------------------------------+ 860 | Multicast Group Length (1 octet) | 861 +--------------------------------------------------+ 862 | Multicast Group Address (Variable) | 863 +--------------------------------------------------+ 864 | Originator Router Length (1 octet) | 865 +--------------------------------------------------+ 866 | Originator Router Address (variable) | 867 +--------------------------------------------------+ 868 | Flags (1 octet) | 869 +--------------------------------------------------+ 871 For the purpose of BGP route key processing, all the fields are 872 considered to be part of the prefix in the NLRI except for the one- 873 octet Flags field, whose fields are defined as follows: 875 0 1 2 3 4 5 6 7 876 +--+--+--+--+--+--+--+--+ 877 | reserved |IE|v3|v2|v1| 878 +--+--+--+--+--+--+--+--+ 880 o The least significant bit, bit 7 indicates support for IGMP 881 version 1. 883 o The second least significant bit, bit 6 indicates support for IGMP 884 version 2. 886 o The third least significant bit, bit 5 indicates support for IGMP 887 version 3. 889 o The fourth least significant bit, bit 4 indicates whether the (S, 890 G) information carried within the route-type is of Include Group 891 type (bit value 0) or an Exclude Group type (bit value 1). The 892 Exclude Group type bit MUST be ignored if bit 5 is not set. 894 o Reserved bits MUST be set to 0. They can be defined in future by 895 other document. 897 The Flags field assists in distributing IGMP Membership Report of a 898 given host/VM for a given multicast route. The version bits help 899 associate IGMP version of receivers participating within the EVPN 900 domain. The include/exclude bit helps in creating filters for a 901 given multicast route. 903 If route is being prepared for IPv6 (MLD) then bit 7 indicates 904 support for MLD version 1. The second least significant bit, bit 6 905 indicates support for MLD version 2. Since there is no MLD version 906 3, in case of IPv6 route third least significant bit MUST be 0. In 907 case of IPv6 route, the fourth least significant bit MUST be ignored 908 if bit 6 is not set. 910 9.2.1. Constructing the Multicast Join Synch Route 912 This section describes the procedures used to construct the IGMP Join 913 Synch route. Support for these route types is optional. If a PE 914 does not support this route, then it MUST NOT indicate that it 915 supports 'IGMP proxy' in the Multicast Flag extended community for 916 the EVIs corresponding to its multi-homed Ethernet Segments (ESs). 918 An IGMP Join Synch route MUST carry exactly one ES-Import Route 919 Target extended community, the one that corresponds to the ES on 920 which the IGMP Join was received. It MUST also carry exactly one 921 EVI-RT EC, the one that corresponds to the EVI on which the IGMP Join 922 was received. See Section 9.5 for details on how to encode and 923 construct the EVI-RT EC. 925 The Route Distinguisher (RD) SHOULD be a Type 1 RD [RFC4364]. The 926 value field comprises an IP address of the PE (typically, the 927 loopback address) followed by a number unique to the PE. 929 The Ethernet Segment Identifier (ESI) MUST be set to the 10-octet 930 value defined for the ES. 932 The Ethernet Tag ID MUST be set as per procedure defined in 933 [RFC7432]. 935 The Multicast Source length MUST be set to length of Multicast Source 936 address in bits. If the Multicast Source field contains an IPv4 937 address, then the value of the Multicast Source Length field is 32. 938 If the Multicast Source field contains an IPv6 address, then the 939 value of the Multicast Source Length field is 128. In case of a 940 (*,G) Join, the Multicast Source Length is set to 0. 942 The Multicast Source is the Source IP address of the IGMP Membership 943 Report. In case of a (*,G) Join, this field does not exist. 945 The Multicast Group length MUST be set to length of multicast group 946 address in bits. If the Multicast Group field contains an IPv4 947 address, then the value of the Multicast Group Length field is 32. 948 If the Multicast Group field contains an IPv6 address, then the value 949 of the Multicast Group Length field is 128. 951 The Multicast Group is the Group address of the IGMP Membership 952 Report. 954 The Originator Router Length is the length of the Originator Router 955 address in bits. 957 The Originator Router Address is the IP address of Router Originating 958 the prefix. 960 The Flags field indicates the version of IGMP protocol from which the 961 Membership Report was received. It also indicates whether the 962 multicast group had INCLUDE or EXCLUDE bit set. 964 Reserved bits MUST be set to 0. They can be defined in future by 965 other document. 967 9.3. Multicast Leave Synch Route 969 This EVPN route type is used to coordinate IGMP Leave Group (x,G) 970 state for a given BD between the PEs attached to a given ES operating 971 in All-Active (or Single-Active) redundancy mode and it consists of 972 following: 974 +--------------------------------------------------+ 975 | RD (8 octets) | 976 +--------------------------------------------------+ 977 | Ethernet Segment Identifier (10 octets) | 978 +--------------------------------------------------+ 979 | Ethernet Tag ID (4 octets) | 980 +--------------------------------------------------+ 981 | Multicast Source Length (1 octet) | 982 +--------------------------------------------------+ 983 | Multicast Source Address (variable) | 984 +--------------------------------------------------+ 985 | Multicast Group Length (1 octet) | 986 +--------------------------------------------------+ 987 | Multicast Group Address (Variable) | 988 +--------------------------------------------------+ 989 | Originator Router Length (1 octet) | 990 +--------------------------------------------------+ 991 | Originator Router Address (variable) | 992 +--------------------------------------------------+ 993 | Reserved (4 octet) | 994 +--------------------------------------------------+ 995 | Maximum Response Time (1 octet) | 996 +--------------------------------------------------+ 997 | Flags (1 octet) | 998 +--------------------------------------------------+ 1000 For the purpose of BGP route key processing, all the fields are 1001 considered to be part of the prefix in the NLRI except for the 1002 Reserved, Maximum Response Time and the one-octet Flags field, whose 1003 fields are defined as follows: 1005 0 1 2 3 4 5 6 7 1006 +--+--+--+--+--+--+--+--+ 1007 | reserved |IE|v3|v2|v1| 1008 +--+--+--+--+--+--+--+--+ 1010 o The least significant bit, bit 7 indicates support for IGMP 1011 version 1. 1013 o The second least significant bit, bit 6 indicates support for IGMP 1014 version 2. 1016 o The third least significant bit, bit 5 indicates support for IGMP 1017 version 3. 1019 o The fourth least significant bit, bit 4 indicates whether the (S, 1020 G) information carried within the route-type is of Include Group 1021 type (bit value 0) or an Exclude Group type (bit value 1). The 1022 Exclude Group type bit MUST be ignored if bit 5 is not set. 1024 o Reserved bits MUST be set to 0. They can be defined in future by 1025 other document. 1027 The Flags field assists in distributing IGMP Membership Report of a 1028 given host/VM for a given multicast route. The version bits help 1029 associate IGMP version of receivers participating within the EVPN 1030 domain. The include/exclude bit helps in creating filters for a 1031 given multicast route. 1033 If route is being prepared for IPv6 (MLD) then bit 7 indicates 1034 support for MLD version 1. The second least significant bit, bit 6 1035 indicates support for MLD version 2. Since there is no MLD version 1036 3, in case of IPv6 route third least significant bit MUST be 0. In 1037 case of IPv6 route, the fourth least significant bit MUST be ignored 1038 if bit 6 is not set. 1040 Reserved bits in flag MUST be set to 0. They can be defined in 1041 future by other document. 1043 9.3.1. Constructing the Multicast Leave Synch Route 1045 This section describes the procedures used to construct the IGMP 1046 Leave Synch route. Support for these route types is optional. If a 1047 PE does not support this route, then it MUST NOT indicate that it 1048 supports 'IGMP proxy' in Multicast Flag extended community for the 1049 EVIs corresponding to its multi-homed Ethernet Segments. 1051 An IGMP Leave Synch route MUST carry exactly one ES-Import Route 1052 Target extended community, the one that corresponds to the ES on 1053 which the IGMP Leave was received. It MUST also carry exactly one 1054 EVI-RT EC, the one that corresponds to the EVI on which the IGMP 1055 Leave was received. See Section 9.5 for details on how to form the 1056 EVI-RT EC. 1058 The Route Distinguisher (RD) SHOULD be a Type 1 RD [RFC4364]. The 1059 value field comprises an IP address of the PE (typically, the 1060 loopback address) followed by a number unique to the PE. 1062 The Ethernet Segment Identifier (ESI) MUST be set to the 10-octet 1063 value defined for the ES. 1065 The Ethernet Tag ID MUST be set as per procedure defined in 1066 [RFC7432]. 1068 The Multicast Source length MUST be set to length of multicast source 1069 address in bits. If the Multicast Source field contains an IPv4 1070 address, then the value of the Multicast Source Length field is 32. 1071 If the Multicast Source field contains an IPv6 address, then the 1072 value of the Multicast Source Length field is 128. In case of a 1073 (*,G) Join, the Multicast Source Length is set to 0. 1075 The Multicast Source is the Source IP address of the IGMP Membership 1076 Report. In case of a (*,G) Join, this field does not exist. 1078 The Multicast Group length MUST be set to length of multicast group 1079 address in bits. If the Multicast Group field contains an IPv4 1080 address, then the value of the Multicast Group Length field is 32. 1081 If the Multicast Group field contains an IPv6 address, then the value 1082 of the Multicast Group Length field is 128. 1084 The Multicast Group is the Group address of the IGMP Membership 1085 Report. 1087 The Originator Router Length is the length of the Originator Router 1088 address in bits. 1090 The Originator Router Address is the IP address of Router Originating 1091 the prefix. 1093 Reserved field is not part of the route key. The originator MUST set 1094 the reserved field to Zero , the receiver SHOULD ignore it and if it 1095 needs to be propagated, it MUST propagate it unchanged 1097 Maximum Response Time is value to be used while sending query as 1098 defined in [RFC2236] 1100 The Flags field indicates the version of IGMP protocol from which the 1101 Membership Report was received. It also indicates whether the 1102 multicast group had INCLUDE or EXCLUDE bit set. 1104 9.4. Multicast Flags Extended Community 1106 The 'Multicast Flags' extended community is a new EVPN extended 1107 community. EVPN extended communities are transitive extended 1108 communities with a Type field value of 6. IANA will assign a Sub- 1109 Type from the 'EVPN Extended Community Sub-Types' registry. 1111 A PE that supports IGMP proxy on a given BD MUST attach this extended 1112 community to the Inclusive Multicast Ethernet Tag (IMET) route it 1113 advertises for that BD and it MUST set the IGMP Proxy Support flag to 1114 1. Note that an [RFC7432] compliant PE will not advertise this 1115 extended community so its absence indicates that the advertising PE 1116 does not support IGMP Proxy. 1118 The advertisement of this extended community enables more efficient 1119 multicast tunnel setup from the source PE specially for ingress 1120 replication - i.e., if an egress PE supports IGMP proxy but doesn't 1121 have any interest in a given (x,G), it advertises its IGMP proxy 1122 capability using this extended community but it does not advertise 1123 any SMET route for that (x,G). When the source PE (ingress PE) 1124 receives such advertisements from the egress PE, it does not 1125 replicate the multicast traffic to that egress PE; however, it does 1126 replicate the multicast traffic to the egress PEs that don't 1127 advertise such capability even if they don't have any interests in 1128 that (x,G). 1130 A Multicast Flags extended community is encoded as an 8-octet value, 1131 as follows: 1133 0 1 2 3 1134 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 1135 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1136 | Type=0x06 | Sub-Type=0x09| Flags (2 Octets) |M|I| 1137 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1138 | Reserved=0 | 1139 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1141 The low-order (lease significant) two bits are defined as the "IGMP 1142 Proxy Support and MLD Proxy Support" bit. The absence of this 1143 extended community also means that the PE does not support IGMP 1144 proxy. where: 1146 o Type is 0x06 as registered with IANA for EVPN Extended 1147 Communities. 1149 o Sub-Type : 0x09 1151 o Flags are two Octets value. 1153 * Bit 15 (shown as I) defines IGMP Proxy Support. Value of 1 for 1154 bit 15 means that PE supports IGMP Proxy. Value of 0 for bit 1155 15 means that PE does not supports IGMP Proxy. 1157 * Bit 14 (shown as M) defines MLD Proxy Support. Value of 1 for 1158 bit 14 means that PE supports MLD Proxy. Value of 0 for bit 14 1159 means that PE does not support MLD proxy. 1161 * Bit 0 to 13 are reserved for future. Sender MUST set it 0 and 1162 receiver MUST ignore it. 1164 o Reserved bits are set to 0. Sender MUST set it to 0 and receiver 1165 MUST ignore it. 1167 If a router does not support this specification, it MUST NOT add 1168 Multicast Flags Extended Community in BGP route. A router receiving 1169 BGP update, if M and I both flag are zero (0), the router MUST treat 1170 this Update as malformed. Receiver of such update MUST ignore the 1171 extended community. 1173 9.5. EVI-RT Extended Community 1175 In EVPN, every EVI is associated with one or more Route Targets 1176 (RTs). These Route Targets serve two functions: 1178 1. Distribution control: RTs control the distribution of the routes. 1179 If a route carries the RT associated with a particular EVI, it 1180 will be distributed to all the PEs on which that EVI exists. 1182 2. EVI identification: Once a route has been received by a 1183 particular PE, the RT is used to identify the EVI to which it 1184 applies. 1186 An IGMP Join Synch or IGMP Leave Synch route is associated with a 1187 particular combination of ES and EVI. These routes need to be 1188 distributed only to PEs that are attached to the associated ES. 1189 Therefore these routes carry the ES-Import RT for that ES. 1191 Since an IGMP Join Synch or IGMP Leave Synch route does not need to 1192 be distributed to all the PEs on which the associated EVI exists, 1193 these routes cannot carry the RT associated with that EVI. 1194 Therefore, when such a route arrives at a particular PE, the route's 1195 RTs cannot be used to identify the EVI to which the route applies. 1196 Some other means of associating the route with an EVI must be used. 1198 This document specifies four new Extended Communities (EC) that can 1199 be used to identify the EVI with which a route is associated, but 1200 which do not have any effect on the distribution of the route. These 1201 new ECs are known as the "Type 0 EVI-RT EC", the "Type 1 EVI-RT EC", 1202 the "Type 2 EVI-RT EC", and the "Type 3 EVI-RT EC". 1204 1. A Type 0 EVI-RT EC is an EVPN EC (type 6) of sub-type 0xA. 1206 2. A Type 1 EVI-RT EC is an EVPN EC (type 6) of sub-type 0xB. 1208 3. A Type 2 EVI-RT EC is an EVPN EC (type 6) of sub-type 0xC. 1210 4. A Type 3 EVI-RT EC is an EVPN EC (type 6) of sub-type 0xD 1212 Each IGMP Join Synch or IGMP Leave Synch route MUST carry exactly one 1213 EVI-RT EC. The EVI-RT EC carried by a particular route is 1214 constructed as follows. Each such route is the result of having 1215 received an IGMP Join or an IGMP Leave message from a particular BD. 1216 The route is said to be associated associated with that BD. For each 1217 BD, there is a corresponding RT that is used to ensure that routes 1218 "about" that BD are distributed to all PEs attached to that BD. So 1219 suppose a given IGMP Join Synch or Leave Synch route is associated 1220 with a given BD, say BD1, and suppose that the corresponding RT for 1221 BD1 is RT1. Then: 1223 o 0. If RT1 is a Transitive Two-Octet AS-specific EC, then the EVI- 1224 RT EC carried by the route is a Type 0 EVI-RT EC. The value field 1225 of the Type 0 EVI-RT EC is identical to the value field of RT1. 1227 o 1. If RT1 is a Transitive IPv4-Address-specific EC, then the EVI- 1228 RT EC carried by the route is a Type 1 EVI-RT EC. The value field 1229 of the Type 1 EVI-RT EC is identical to the value field of RT1. 1231 o 2. If RT1 is a Transitive Four-Octet-specific EC, then the EVI-RT 1232 EC carried by the route is a Type 2 EVI-RT EC. The value field of 1233 the Type 2 EVI-RT EC is identical to the value field of RT1. 1235 o 3. If RT1 is a Transitive IPv6-Address-specific EC, then the EVI- 1236 RT EC carried by the route is a Type 3 EVI-RT EC. The value field 1237 of the Type 3 EVI-RT EC is identical to the value field of RT1. 1239 An IGMP Join Synch or Leave Synch route MUST carry exactly one EVI-RT 1240 EC. 1242 Suppose a PE receives a particular IGMP Join Synch or IGMP Leave 1243 Synch route, say R1, and suppose that R1 carries an ES-Import RT that 1244 is one of the PE's Import RTs. If R1 has no EVI-RT EC, or has more 1245 than one EVI-RT EC, the PE MUST apply the "treat-as-withdraw" 1246 procedure of [RFC7606]. 1248 Note that an EVI-RT EC is not a Route Target Extended Community, is 1249 not visible to the RT Constrain mechanism [RFC4684], and is not 1250 intended to influence the propagation of routes by BGP. 1252 1 2 3 1253 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 1254 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1255 | Type=0x06 | Sub-Type=n | RT associated with EVI | 1256 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1257 | RT associated with the EVI (cont.) | 1258 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1260 Where the value of 'n' is 0x0A, 0x0B, 0x0C, or 0x0D corresponding to 1261 EVI-RT type 0, 1, 2, or 3 respectively. 1263 9.6. Rewriting of RT ECs and EVI-RT ECs by ASBRs 1265 There are certain situations in which an ES is attached to a set of 1266 PEs that are not all in the same AS, or not all operated by the same 1267 provider. In some such situations, the RT that corresponds to a 1268 particular EVI may be different in each AS. If a route is propagated 1269 from AS1 to AS2, an ASBR at the AS1/AS2 border may be provisioned 1270 with a policy that removes the RTs that are meaningful in AS1 and 1271 replaces them with the corresponding (i.e., RTs corresponding to the 1272 same EVIs) RTs that are meaningful in AS2. This is known as RT- 1273 rewriting. 1275 Note that if a given route's RTs are rewritten, and the route carries 1276 an EVI-RT EC, the EVI-RT EC needs to be rewritten as well. 1278 9.7. BGP Error Handling 1280 If a received BGP update contains Flags not in accordance with IGMP/ 1281 MLD version-X expectation, the PE MUST apply the "treat-as-withdraw" 1282 procedure as per [RFC7606] 1284 If a received BGP update is malformed such that BGP route keys cannot 1285 be extracted, then BGP update MUST be considered as invalid. 1286 Receiving PE MUST apply the "Session reset" procedure of [RFC7606]. 1288 10. IGMP/MLD Immediate Leave 1290 IGMP MAY be configured with immediate leave option. This allows the 1291 device to remove the group entry from the multicast routing table 1292 immediately upon receiving a IGMP leave message for (x,G). In case 1293 of all active multi-homing while synchronizing the IGMP Leave state 1294 to redundancy peers, Maximum Response Time MAY be filled in as Zero. 1295 Implementations SHOULD have identical configuration across multi- 1296 homed peers. In case IGMP Leave Synch route is received with Maximum 1297 Response Time Zero, irrespective of local IGMP configuration it MAY 1298 be processed as an immediate leave. 1300 11. IGMP Version 1 Membership Report 1302 This document does not provide any detail about IGMPv1 processing. 1303 Multicast working group are in process of deprecating uses of IGMPv1. 1304 Implementations MUST only use IGMPv2 and above for IPv4 and MLDv1 and 1305 above for IPv6. IGMP V1 routes MUST be considered as invalid and the 1306 PE MUST apply the "treat-as-withdraw" procedure as per [RFC7606]. 1307 Initial version of draft did mention use of IGMPv1 and flag had 1308 provision to support IGMPv1. There may be an implemention which is 1309 deployed as initial version of draft, to interop flag has not been 1310 changed. 1312 12. Security Considerations 1314 TThis document does not add any new security considirattions, Same 1315 security considerations as [RFC7432], [RFC2236], [RFC3376], 1316 [RFC2710], [RFC3810], [RFC6513], [RFC6514] are applicable. 1318 13. IANA Considerations 1320 IANA has allocated the following codepoints from the EVPN Extended 1321 Community sub-types registry. 1323 0x09 Multicast Flags Extended Community [this document] 1324 0x0A EVI-RT Type 0 [this document] 1325 0x0B EVI-RT Type 1 [this document] 1326 0x0C EVI-RT Type 2 [this document] 1328 IANA is requested to allocate a new codepoint from the EVPN Extended 1329 Community sub-types registry for the following. 1331 0x0D EVI-RT Type 3 [this document] 1333 IANA has allocated the following EVPN route types from the EVPN Route 1334 Type registry. 1336 6 - Selective Multicast Ethernet Tag Route 1337 7 - Multicast Join Synch Route 1338 8 - Multicast Leave Synch Route 1340 The Multicast Flags Extended Community contains a 16-bit Flags field. 1341 The bits are numbered 0-15, from high-order to low-order. 1343 The registry should be initialized as follows: 1344 Bit Name Reference 1345 ---- -------------- ------------- 1346 0 - 13 Unassigned 1347 14 MLD Proxy Support This document 1348 15 IGMP Proxy Support This document 1350 The registration policy should be "First Come First Served". 1352 14. Acknowledgement 1354 The authors would like to thank Stephane Litkowski, Jorge Rabadan, 1355 Anoop Ghanwani, Jeffrey Haas, Krishna Muddenahally Ananthamurthy, 1356 Swadesh Agrawal for reviewing and providing valuable comment. 1358 15. Contributors 1360 Derek Yeung 1362 Arrcus 1364 Email: derek@arrcus.com 1366 16. References 1368 16.1. Normative References 1370 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1371 Requirement Levels", BCP 14, RFC 2119, 1372 DOI 10.17487/RFC2119, March 1997, 1373 . 1375 [RFC2236] Fenner, W., "Internet Group Management Protocol, Version 1376 2", RFC 2236, DOI 10.17487/RFC2236, November 1997, 1377 . 1379 [RFC2710] Deering, S., Fenner, W., and B. Haberman, "Multicast 1380 Listener Discovery (MLD) for IPv6", RFC 2710, 1381 DOI 10.17487/RFC2710, October 1999, 1382 . 1384 [RFC3376] Cain, B., Deering, S., Kouvelas, I., Fenner, B., and A. 1385 Thyagarajan, "Internet Group Management Protocol, Version 1386 3", RFC 3376, DOI 10.17487/RFC3376, October 2002, 1387 . 1389 [RFC3810] Vida, R., Ed. and L. Costa, Ed., "Multicast Listener 1390 Discovery Version 2 (MLDv2) for IPv6", RFC 3810, 1391 DOI 10.17487/RFC3810, June 2004, 1392 . 1394 [RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private 1395 Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February 1396 2006, . 1398 [RFC4684] Marques, P., Bonica, R., Fang, L., Martini, L., Raszuk, 1399 R., Patel, K., and J. Guichard, "Constrained Route 1400 Distribution for Border Gateway Protocol/MultiProtocol 1401 Label Switching (BGP/MPLS) Internet Protocol (IP) Virtual 1402 Private Networks (VPNs)", RFC 4684, DOI 10.17487/RFC4684, 1403 November 2006, . 1405 [RFC6513] Rosen, E., Ed. and R. Aggarwal, Ed., "Multicast in MPLS/ 1406 BGP IP VPNs", RFC 6513, DOI 10.17487/RFC6513, February 1407 2012, . 1409 [RFC6514] Aggarwal, R., Rosen, E., Morin, T., and Y. Rekhter, "BGP 1410 Encodings and Procedures for Multicast in MPLS/BGP IP 1411 VPNs", RFC 6514, DOI 10.17487/RFC6514, February 2012, 1412 . 1414 [RFC6625] Rosen, E., Ed., Rekhter, Y., Ed., Hendrickx, W., and R. 1415 Qiu, "Wildcards in Multicast VPN Auto-Discovery Routes", 1416 RFC 6625, DOI 10.17487/RFC6625, May 2012, 1417 . 1419 [RFC7432] Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A., 1420 Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based 1421 Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432, February 1422 2015, . 1424 [RFC7606] Chen, E., Ed., Scudder, J., Ed., Mohapatra, P., and K. 1425 Patel, "Revised Error Handling for BGP UPDATE Messages", 1426 RFC 7606, DOI 10.17487/RFC7606, August 2015, 1427 . 1429 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1430 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1431 May 2017, . 1433 16.2. Informative References 1435 [I-D.ietf-bess-evpn-bum-procedure-updates] 1436 Zhang, Z., Lin, W., Rabadan, J., Patel, K., and A. 1437 Sajassi, "Updates on EVPN BUM Procedures", draft-ietf- 1438 bess-evpn-bum-procedure-updates-08 (work in progress), 1439 November 2019. 1441 [RFC4541] Christensen, M., Kimball, K., and F. Solensky, 1442 "Considerations for Internet Group Management Protocol 1443 (IGMP) and Multicast Listener Discovery (MLD) Snooping 1444 Switches", RFC 4541, DOI 10.17487/RFC4541, May 2006, 1445 . 1447 Authors' Addresses 1449 Ali Sajassi 1450 Cisco Systems 1451 821 Alder Drive, 1452 MILPITAS, CALIFORNIA 95035 1453 UNITED STATES 1455 Email: sajassi@cisco.com 1457 Samir Thoria 1458 Cisco Systems 1459 821 Alder Drive, 1460 MILPITAS, CALIFORNIA 95035 1461 UNITED STATES 1463 Email: sthoria@cisco.com 1465 Mankamana Mishra 1466 Cisco Systems 1467 821 Alder Drive, 1468 MILPITAS, CALIFORNIA 95035 1469 UNITED STATES 1471 Email: mankamis@cisco.com 1473 Keyur PAtel 1474 Arrcus 1475 UNITED STATES 1477 Email: keyur@arrcus.com 1478 John Drake 1479 Juniper Networks 1481 Email: jdrake@juniper.net 1483 Wen Lin 1484 Juniper Networks 1486 Email: wlin@juniper.net