idnits 2.17.1 draft-ietf-bess-evpn-optimized-ir-07.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (July 13, 2020) is 1382 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-14) exists of draft-ietf-bess-evpn-bum-procedure-updates-08 Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 1 comment (--).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 J. Rabadan, Ed. 3 Internet-Draft S. Sathappan 4 Intended status: Standards Track Nokia 5 Expires: January 14, 2021 W. Lin 6 Juniper Networks 7 M. Katiyar 8 Versa Networks 9 A. Sajassi 10 Cisco Systems 11 July 13, 2020 13 Optimized Ingress Replication solution for EVPN 14 draft-ietf-bess-evpn-optimized-ir-07 16 Abstract 18 Network Virtualization Overlay (NVO) networks using EVPN as control 19 plane may use Ingress Replication (IR) or PIM (Protocol Independent 20 Multicast) based trees to convey the overlay BUM traffic. PIM 21 provides an efficient solution to avoid sending multiple copies of 22 the same packet over the same physical link, however it may not 23 always be deployed in the NVO core network. IR avoids the dependency 24 on PIM in the NVO network core. While IR provides a simple multicast 25 transport, some NVO networks with demanding multicast applications 26 require a more efficient solution without PIM in the core. This 27 document describes a solution to optimize the efficiency of IR in NVO 28 networks. 30 Status of This Memo 32 This Internet-Draft is submitted in full conformance with the 33 provisions of BCP 78 and BCP 79. 35 Internet-Drafts are working documents of the Internet Engineering 36 Task Force (IETF). Note that other groups may also distribute 37 working documents as Internet-Drafts. The list of current Internet- 38 Drafts is at https://datatracker.ietf.org/drafts/current/. 40 Internet-Drafts are draft documents valid for a maximum of six months 41 and may be updated, replaced, or obsoleted by other documents at any 42 time. It is inappropriate to use Internet-Drafts as reference 43 material or to cite them other than as "work in progress." 45 This Internet-Draft will expire on January 14, 2021. 47 Copyright Notice 49 Copyright (c) 2020 IETF Trust and the persons identified as the 50 document authors. All rights reserved. 52 This document is subject to BCP 78 and the IETF Trust's Legal 53 Provisions Relating to IETF Documents 54 (https://trustee.ietf.org/license-info) in effect on the date of 55 publication of this document. Please review these documents 56 carefully, as they describe your rights and restrictions with respect 57 to this document. Code Components extracted from this document must 58 include Simplified BSD License text as described in Section 4.e of 59 the Trust Legal Provisions and are provided without warranty as 60 described in the Simplified BSD License. 62 Table of Contents 64 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 65 2. Terminology and Conventions . . . . . . . . . . . . . . . . . 4 66 3. Solution requirements . . . . . . . . . . . . . . . . . . . . 6 67 4. EVPN BGP Attributes for optimized-IR . . . . . . . . . . . . 6 68 5. Non-selective Assisted-Replication (AR) Solution Description 10 69 5.1. Non-selective AR-REPLICATOR procedures . . . . . . . . . 11 70 5.2. Non-selective AR-LEAF procedures . . . . . . . . . . . . 12 71 5.3. RNVE procedures . . . . . . . . . . . . . . . . . . . . . 15 72 6. Selective Assisted-Replication (AR) Solution Description . . 15 73 6.1. Selective AR-REPLICATOR procedures . . . . . . . . . . . 15 74 6.2. Selective AR-LEAF procedures . . . . . . . . . . . . . . 18 75 7. Pruned-Flood-Lists (PFL) . . . . . . . . . . . . . . . . . . 19 76 7.1. A PFL example . . . . . . . . . . . . . . . . . . . . . . 20 77 8. AR Procedures for single-IP AR-REPLICATORS . . . . . . . . . 21 78 9. AR Procedures and EVPN All-Active Multi-homing Split-Horizon 21 79 9.1. Ethernet Segments on AR-LEAF nodes . . . . . . . . . . . 22 80 9.2. Ethernet Segments on AR-REPLICATOR nodes . . . . . . . . 22 81 10. Security Considerations . . . . . . . . . . . . . . . . . . . 23 82 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23 83 12. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 24 84 13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 24 85 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 24 86 14.1. Normative References . . . . . . . . . . . . . . . . . . 24 87 14.2. Informative References . . . . . . . . . . . . . . . . . 25 88 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 25 90 1. Introduction 92 Ethernet Virtual Private Networks (EVPN) may be used as the control 93 plane for a Network Virtualization Overlay (NVO) network. Network 94 Virtualization Edge (NVE) devices and Provider Edges (PEs) that are 95 part of the same EVPN Instance (EVI) use Ingress Replication (IR) or 96 PIM-based trees to transport the tenant's BUM traffic. In NVO 97 networks where PIM-based trees cannot be used, IR is the only option. 98 Examples of these situations are NVO networks where the core nodes 99 don't support PIM or the network operator does not want to run PIM in 100 the core. 102 In some use-cases, the amount of replication for BUM (Broadcast, 103 Unknown unicast and Multicast traffic) is kept under control on the 104 NVEs due to the following fairly common assumptions: 106 a. Broadcast is greatly reduced due to the proxy ARP (Address 107 Resolution Protocol) and proxy ND (Neighbor Discovery) 108 capabilities supported by EVPN on the NVEs. Some NVEs can even 109 provide Dynamic Host Configuration Protocol (DHCP) server 110 functions for the attached Tenant Systems (TS) reducing the 111 broadcast even further. 113 b. Unknown unicast traffic is greatly reduced in virtualized NVO 114 networks where all the MAC and IP addresses are learned in the 115 control plane. 117 c. Multicast applications are not used. 119 If the above assumptions are true for a given NVO network, then IR 120 provides a simple solution for multi-destination traffic. However, 121 the statement c) above is not always true and multicast applications 122 are required in many use-cases. 124 When the multicast sources are attached to NVEs residing in 125 hypervisors or low-performance-replication TORs (Top Of Rack 126 switches), the ingress replication of a large amount of multicast 127 traffic to a significant number of remote NVEs/PEs can seriously 128 degrade the performance of the NVE and impact the application. 130 This document describes a solution that makes use of two IR 131 optimizations: 133 1. Assisted-Replication (AR) 135 2. Pruned-Flood-Lists (PFL) 137 Both optimizations may be used together or independently so that the 138 performance and efficiency of the network to transport multicast can 139 be improved. Both solutions require some extensions to [RFC7432] 140 that are described in Section 4. 142 Section 3 lists the requirements of the combined optimized-IR 143 solution, whereas Section 5 and Section 6 describe the Assisted- 144 Replication (AR) solution, and Section 7 the Pruned-Flood-Lists (PFL) 145 solution. 147 2. Terminology and Conventions 149 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 150 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 151 "OPTIONAL" in this document are to be interpreted as described in BCP 152 14 [RFC2119] [RFC8174] when, and only when, they appear in all 153 capitals, as shown here. 155 The following terminology is used throughout the document: 157 - AC: Attachment Circuit 159 - BM traffic: Refers to Broadcast and Multicast frames (excluding 160 unknown unicast frames) 162 - NVO: Network Virtualization Overlay 164 - NVE: Network Virtualization Edge router 166 - PE: Provider Edge router 168 - AR-REPLICATOR: Assisted Replication - REPLICATOR, refers to an 169 NVE/PE that can replicate Broadcast en Multicast traffic received 170 on overlay tunnels to other overlay tunnels. This document 171 defines the control and data plane procedures that an AR- 172 REPLICATOR needs to follow. 174 - AR-LEAF: Assisted Replication - LEAF, refers to an NVE/PE that - 175 given its poor replication performance - sends all the Broadcast 176 and Multicast traffic to an AR-REPLICATOR that can replicate the 177 traffic further on its behalf. 179 - RNVE: Regular NVE, refers to an NVE that supports the procedures 180 of [RFC8365] and does not support the procedures in this document. 181 However, this document defines procedures to interoperate with 182 RNVEs. 184 - Replicator-AR route: an EVPN RT-3 (route type 3) that is 185 advertised by an AR-REPLICATOR to signal its capabilities. 187 - Regular-IR: Refers to Regular Ingress Replication, where the 188 source NVE/PE sends a copy to each remote NVE/PE part of the BD. 190 - AR-IP: IP address owned by the AR-REPLICATOR and used to 191 differentiate the ingress traffic that must follow the AR 192 procedures. 194 - IR-IP: IP address used for Ingress Replication as in [RFC7432]. 196 - AR-VNI: VNI advertised by the AR-REPLICATOR along with the 197 Replicator-AR route. It is used to identify the ingress packets 198 that must follow AR procedures ONLY in the Single-IP AR-REPLICATOR 199 case. 201 - IR-VNI: VNI advertised along with the RT-3 for IR. 203 - AR forwarding mode: for an AR-LEAF, it means sending an AC BM 204 packet to a single AR-REPLICATOR with tunnel destination IP AR-IP. 205 For an AR-REPLICATOR, it means sending a BM packet to a selected 206 number or all the overlay tunnels when the packet was previously 207 received from an overlay tunnel. 209 - IR forwarding mode: it refers to the Ingress Replication behavior 210 explained in [RFC7432]. It means sending an AC BM packet copy to 211 each remote PE/NVE in the BD and sending an overlay BM packet only 212 to the ACs and not other overlay tunnels. 214 - PTA: PMSI Tunnel Attribute 216 - RT-3: EVPN Route Type 3, Inclusive Multicast Ethernet Tag route 218 - RT-11: EVPN Route Type 11, Leaf Auto-Discovery (AD) route 220 - VXLAN: Virtual Extensible LAN 222 - GRE: Generic Routing Encapsulation 224 - NVGRE: Network Virtualization using Generic Routing Encapsulation 226 - GENEVE: Generic Network Virtualization Encapsulation 228 - VNI: VXLAN Network Identifier 230 - EVI: EVPN Instance. An EVPN instance spanning the Provider Edge 231 (PE) devices participating in that EVPN 233 - BD: Broadcast Domain, as defined in [RFC7432]. 235 - TOR: Top Of Rack switch 237 3. Solution requirements 239 The IR optimization solution specified in this document (optimized-IR 240 hereafter) meets the following requirements: 242 a. It provides an IR optimization for BM (Broadcast and Multicast) 243 traffic without the need for PIM, while preserving the packet 244 order for unicast applications, i.e., known and unknown unicast 245 traffic should follow the same path. This optimization is 246 required in low-performance NVEs. 248 b. It reduces the flooded traffic in NVO networks where some NVEs do 249 not need broadcast/multicast and/or unknown unicast traffic. 251 c. The solution is compatible with [RFC7432] and [RFC8365] and has 252 no impact on the EVPN procedures for BM traffic. In particular, 253 the solution supports the following EVPN functions: 255 o All-active multi-homing, including the split-horizon and 256 Designated Forwarder (DF) functions. 258 o Single-active multi-homing, including the DF function. o 259 Handling of multi-destination traffic and processing of 260 broadcast and multicast as per [RFC7432]. 262 d. The solution is backwards compatible with existing NVEs using a 263 non-optimized version of IR. A given BD can have NVEs/PEs 264 supporting regular-IR and optimized-IR. 266 e. The solution is independent of the NVO specific data plane 267 encapsulation and the virtual identifiers being used, e.g.: VXLAN 268 VNIs, NVGRE VSIDs or MPLS labels, as long as the tunnel is IP- 269 based. 271 4. EVPN BGP Attributes for optimized-IR 273 This solution extends the [RFC7432] Inclusive Multicast Ethernet Tag 274 routes and attributes so that an NVE/PE can signal its optimized-IR 275 capabilities. 277 The Inclusive Multicast Ethernet Tag route (RT-3) and its PMSI Tunnel 278 Attribute's (PTA) general format used in [RFC7432] are shown below: 280 +---------------------------------+ 281 | RD (8 octets) | 282 +---------------------------------+ 283 | Ethernet Tag ID (4 octets) | 284 +---------------------------------+ 285 | IP Address Length (1 octet) | 286 +---------------------------------+ 287 | Originating Router's IP Addr | 288 | (4 or 16 octets) | 289 +---------------------------------+ 291 +---------------------------------+ 292 | Flags (1 octet) | 293 +---------------------------------+ 294 | Tunnel Type (1 octets) | 295 +---------------------------------+ 296 | MPLS Label (3 octets) | 297 +---------------------------------+ 298 | Tunnel Identifier (variable) | 299 +---------------------------------+ 301 The Flags field is 8 bits long. This document defines the use of 4 302 bits of this Flags field: 304 - bits 3 and 4, forming together the Assisted-Replication Type (T) 305 field 307 - bit 5, called the Broadcast and Multicast (BM) flag 309 - bit 6, called the Unknown (U) flag 311 Bits 5 and 6 are collectively referred to as the PFL (Pruned-Flood 312 Lists) flags. 314 The T field and PFL flags are defined as follows: 316 - T is the AR Type field (2 bits) that defines the AR role of the 317 advertising router: 319 o 00 (decimal 0) = RNVE (non-AR support) 321 o 01 (decimal 1) = AR-REPLICATOR 323 o 10 (decimal 2) = AR-LEAF 325 o 11 (decimal 3) = RESERVED 327 - The PFL (Pruned-Flood-Lists) flags define the desired behavior of 328 the advertising router for the different types of traffic: 330 o BM= Broadcast and Multicast (BM) flag. BM=1 means "prune-me" 331 from the BM flooding list. BM=0 means regular behavior. 333 o U= Unknown flag. U=1 means "prune-me" from the Unknown 334 flooding list. U=0 means regular behavior. 336 - Flag L is an existing flag defined in [RFC6514] (L=Leaf 337 Information Required) and it will be used only in the Selective AR 338 Solution. 340 Please refer to Section 11 for the IANA considerations related to the 341 PTA flags. 343 In this document, the above RT-3 and PTA can be used in two different 344 modes for the same BD: 346 - Regular-IR route: in this route, Originating Router's IP Address, 347 Tunnel Type (0x06), MPLS Label and Tunnel Identifier MUST be used 348 as described in [RFC7432] when Ingress Replication is in use. The 349 NVE/PE that advertises the route will set the Next-Hop to an IP 350 address that we denominate IR-IP in this document. When 351 advertised by an AR-LEAF node, the Regular-IR route SHOULD be 352 advertised with type T= AR-LEAF. 354 - Replicator-AR route: this route is used by the AR-REPLICATOR to 355 advertise its AR capabilities, with the fields set as follows: 357 o Originating Router's IP Address MUST be set to an IP address of 358 the PE that should be common to all the EVIs on the PE (usually 359 this is the PE's loopback address). The Tunnel Identifier and 360 Next-Hop SHOULD be set to the same IP address as the 361 Originating Router's IP address when the NVE/PE originates the 362 route. The Next-Hop address is referred to as the AR-IP and 363 SHOULD be different than the IR-IP for a given PE/NVE. 365 o Tunnel Type = Assisted-Replication Tunnel. Section 11 provides 366 the allocated type value. 368 o T (AR role type) = 01 (AR-REPLICATOR). 370 o L (Leaf Information Required) = 0 (for non-selective AR) or 1 371 (for selective AR). 373 In addition, this document also uses the Leaf-AD route (RT-11) 374 defined in [I-D.ietf-bess-evpn-bum-procedure-updates] in case the 375 selective AR mode is used. The Leaf-AD route MAY be used by the AR- 376 LEAF in response to a Replicator-AR route (with the L flag set) to 377 advertise its desire to receive the BM traffic from a specific AR- 378 REPLICATOR. It is only used for selective AR and its fields are set 379 as follows: 381 o Originating Router's IP Address is set to the advertising PE's 382 IP address (same IP used by the AR-LEAF in regular-IR routes). 383 The Next-Hop address is set to the IR-IP. 385 o Route Key is the "Route Type Specific" NLRI of the Replicator- 386 AR route for which this Leaf-AD route is generated. 388 o The AR-LEAF constructs an IP-address-specific route-target as 389 indicated in [I-D.ietf-bess-evpn-bum-procedure-updates], by 390 placing the IP address carried in the Next-Hop field of the 391 received Replicator-AR route in the Global Administrator field 392 of the Community, with the Local Administrator field of this 393 Community set to 0. Note that the same IP-address-specific 394 import route-target is auto-configured by the AR-REPLICATOR 395 that sent the Replicator-AR, in order to control the acceptance 396 of the Leaf-AD routes. 398 o The leaf-AD route MUST include the PMSI Tunnel attribute with 399 the Tunnel Type set to AR, type set to AR-LEAF and the Tunnel 400 Identifier set to the IP of the advertising AR-LEAF. The PMSI 401 Tunnel attribute MUST carry a downstream-assigned MPLS label or 402 VNI that is used by the AR-REPLICATOR to send traffic to the 403 AR-LEAF. 405 Each AR-enabled node MUST understand and process the AR type field in 406 the PTA (Flags field) of the routes, and MUST signal the 407 corresponding type (1 or 2) according to its administrative choice. 409 Each node attached to the BD may understand and process the BM/U 410 flags. Note that these BM/U flags may be used to optimize the 411 delivery of multi-destination traffic and its use SHOULD be an 412 administrative choice, and independent of the AR role. 414 Non-optimized-IR nodes will be unaware of the new PMSI attribute flag 415 definition as well as the new Tunnel Type (AR), i.e. they will ignore 416 the information contained in the flags field for any RT-3 and will 417 ignore the RT-3 routes with an unknown Tunnel Type (type AR in this 418 case). 420 5. Non-selective Assisted-Replication (AR) Solution Description 422 Figure 1 illustrates an example NVO network where the non-selective 423 AR function is enabled. Three different roles are defined for a 424 given BD: AR-REPLICATOR, AR-LEAF and RNVE (Regular NVE). The 425 solution is called "non-selective" because the chosen AR-REPLICATOR 426 for a given flow MUST replicate the BM traffic to 'all' the NVE/PEs 427 in the BD except for the source NVE/PE. 429 ( ) 430 (_ WAN _) 431 +---(_ _)----+ 432 | (_ _) | 433 PE1 | PE2 | 434 +------+----+ +----+------+ 435 TS1--+ (BD-1) | | (BD-1) +--TS2 436 |REPLICATOR | |REPLICATOR | 437 +--------+--+ +--+--------+ 438 | | 439 +--+----------------+--+ 440 | | 441 | | 442 +----+ VXLAN/nvGRE/MPLSoGRE +----+ 443 | | IP Fabric | | 444 | | | | 445 NVE1 | +-----------+----------+ | NVE3 446 Hypervisor| TOR | NVE2 |Hypervisor 447 +---------+-+ +-----+-----+ +-+---------+ 448 | (BD-1) | | (BD-1) | | (BD-1) | 449 | LEAF | | RNVE | | LEAF | 450 +--+-----+--+ +--+-----+--+ +--+-----+--+ 451 | | | | | | 452 VM11 VM12 TS3 TS4 VM31 VM32 454 Figure 1: Optimized-IR scenario 456 In AR BDs such as BD-1 in the example, BM (Broadcast and Multicast) 457 traffic between two NVEs may follow a different path than unicast 458 traffic. This solution recommends the replication of BM through the 459 AR-REPLICATOR node, whereas unknown/known unicast will be delivered 460 directly from the source node to the destination node without being 461 replicated by any intermediate node. Unknown unicast SHALL follow 462 the same path as known unicast traffic in order to avoid packet 463 reordering for unicast applications and simplify the control and data 464 plane procedures. 466 Note that known unicast forwarding is not impacted by this solution. 468 5.1. Non-selective AR-REPLICATOR procedures 470 An AR-REPLICATOR is defined as an NVE/PE capable of replicating 471 ingress BM (Broadcast and Multicast) traffic received on an overlay 472 tunnel to other overlay tunnels and local Attachment Circuits (ACs). 473 The AR-REPLICATOR signals its role in the control plane and 474 understands where the other roles (AR-LEAF nodes, RNVEs and other AR- 475 REPLICATORs) are located. A given AR-enabled BD service may have 476 zero, one or more AR-REPLICATORs. In our example in Figure 1, PE1 477 and PE2 are defined as AR-REPLICATORs. The following considerations 478 apply to the AR-REPLICATOR role: 480 a. The AR-REPLICATOR role SHOULD be an administrative choice in any 481 NVE/PE that is part of an AR-enabled BD. This administrative 482 option to enable AR-REPLICATOR capabilities MAY be implemented as 483 a system level option as opposed to as a per-BD option. 485 b. An AR-REPLICATOR MUST advertise a Replicator-AR route and MAY 486 advertise a Regular-IR route. The AR-REPLICATOR MUST NOT 487 generate a Regular-IR route if it does not have local attachment 488 circuits (AC). If the Regular-IR route is advertised, the AR 489 Type field is set to zero. 491 c. The Replicator-AR and Regular-IR routes are generated according 492 to section 3. The AR-IP and IR-IP used by the AR-REPLICATOR are 493 different routable IP addresses. 495 d. When a node defined as AR-REPLICATOR receives a BM packet on an 496 overlay tunnel, it will do a tunnel destination IP lookup and 497 apply the following procedures: 499 o If the destination IP is the AR-REPLICATOR IR-IP Address the 500 node will process the packet normally as in [RFC7432]. 502 o If the destination IP is the AR-REPLICATOR AR-IP Address the 503 node MUST replicate the packet to local ACs and overlay 504 tunnels (excluding the overlay tunnel to the source of the 505 packet). When replicating to remote AR-REPLICATORs the tunnel 506 destination IP will be an IR-IP. That will be an indication 507 for the remote AR-REPLICATOR that it MUST NOT replicate to 508 overlay tunnels. The tunnel source IP used by the AR- 509 REPLICATOR MUST be its IR-IP when replicating to either AR- 510 REPLICATOR or AR-LEAF nodes. 512 An AR-REPLICATOR will follow a data path implementation compatible 513 with the following rules: 515 - The AR-REPLICATORs will build a flooding list composed of ACs and 516 overlay tunnels to remote nodes in the BD. Some of those overlay 517 tunnels MAY be flagged as non-BM receivers based on the BM flag 518 received from the remote nodes in the BD. 520 - When an AR-REPLICATOR receives a BM packet on an AC, it will 521 forward the BM packet to its flooding list (including local ACs 522 and remote NVE/PEs), skipping the non-BM overlay tunnels. 524 - When an AR-REPLICATOR receives a BM packet on an overlay tunnel, 525 it will check the destination IP of the underlay IP header and: 527 o If the destination IP matches its AR-IP, the AR-REPLICATOR will 528 forward the BM packet to its flooding list (ACs and overlay 529 tunnels) excluding the non-BM overlay tunnels. The AR- 530 REPLICATOR will do source squelching to ensure the traffic is 531 not sent back to the originating AR-LEAF. 533 o If the destination IP matches its IR-IP, the AR-REPLICATOR will 534 skip all the overlay tunnels from the flooding list, i.e. it 535 will only replicate to local ACs. This is the regular IR 536 behavior described in [RFC7432]. 538 - While the forwarding behavior in AR-REPLICATORs and AR-LEAF nodes 539 is different for BM traffic, as far as Unknown unicast traffic 540 forwarding is concerned, AR-LEAF nodes behave exactly in the same 541 way as AR-REPLICATORs do. 543 - The AR-REPLICATOR/LEAF nodes will build an Unknown unicast flood- 544 list composed of ACs and overlay tunnels to the IR-IP Addresses of 545 the remote nodes in the BD. Some of those overlay tunnels MAY be 546 flagged as non-U (Unknown unicast) receivers based on the U flag 547 received from the remote nodes in the BD. 549 o When an AR-REPLICATOR/LEAF receives an unknown packet on an AC, 550 it will forward the unknown packet to its flood-list, skipping 551 the non-U overlay tunnels. 553 o When an AR-REPLICATOR/LEAF receives an unknown packet on an 554 overlay tunnel will forward the unknown packet to its local ACs 555 and never to an overlay tunnel. This is the regular IR 556 behavior described in [RFC7432]. 558 5.2. Non-selective AR-LEAF procedures 560 AR-LEAF is defined as an NVE/PE that - given its poor replication 561 performance - sends all the BM traffic to an AR-REPLICATOR that can 562 replicate the traffic further on its behalf. It MAY signal its AR- 563 LEAF capability in the control plane and understands where the other 564 roles are located (AR-REPLICATOR and RNVEs). A given service can 565 have zero, one or more AR-LEAF nodes. Figure 1 shows NVE1 and NVE3 566 (both residing in hypervisors) acting as AR-LEAF. The following 567 considerations apply to the AR-LEAF role: 569 a. The AR-LEAF role SHOULD be an administrative choice in any NVE/PE 570 that is part of an AR-enabled BD. This administrative option to 571 enable AR-LEAF capabilities MAY be implemented as a system level 572 option as opposed to as per-BD option. 574 b. In this non-selective AR solution, the AR-LEAF MUST advertise a 575 single Regular-IR inclusive multicast route as in [RFC7432]. The 576 AR-LEAF SHOULD set the AR Type field to AR-LEAF. Note that 577 although this flag does not make any difference for the egress 578 nodes when creating an EVPN destination to the AR-LEAF, it is 579 RECOMMENDED to use this flag for an easy operation and 580 troubleshooting of the BD. 582 c. In a service where there are no AR-REPLICATORs, the AR-LEAF MUST 583 use regular ingress replication. This will happen when a new 584 update from the last former AR-REPLICATOR is received and 585 contains a non-REPLICATOR AR type, or when the AR-LEAF detects 586 that the last AR-REPLICATOR is down (via next-hop tracking in the 587 IGP or any other detection mechanism). Ingress replication MUST 588 use the forwarding information given by the remote Regular-IR 589 Inclusive Multicast Routes as described in [RFC7432]. 591 d. In a service where there is one or more AR-REPLICATORs (based on 592 the received Replicator-AR routes for the BD), the AR-LEAF can 593 locally select which AR-REPLICATOR it sends the BM traffic to: 595 o A single AR-REPLICATOR MAY be selected for all the BM packets 596 received on the AR-LEAF attachment circuits (ACs) for a given 597 BD. This selection is a local decision and it does not have 598 to match other AR-LEAF's selection within the same BD. 600 o An AR-LEAF MAY select more than one AR-REPLICATOR and do 601 either per-flow or per-BD load balancing. 603 o In case of a failure on the selected AR-REPLICATOR, another 604 AR-REPLICATOR will be selected. 606 o When an AR-REPLICATOR is selected, the AR-LEAF MUST send all 607 the BM packets to that AR-REPLICATOR using the forwarding 608 information given by the Replicator-AR route for the chosen 609 AR-REPLICATOR, with tunnel type = 0x0A (AR tunnel). The 610 underlay destination IP address MUST be the AR-IP advertised 611 by the AR-REPLICATOR in the Replicator-AR route. 613 o AR-LEAF nodes SHALL send service-level BM control plane 614 packets following regular IR procedures. An example would be 615 IGMP, MLD or PIM multicast packets. The AR-REPLICATORs MUST 616 NOT replicate these control plane packets to other overlay 617 tunnels since they will use the regular IR-IP Address. 619 e. The use of an AR-REPLICATOR-activation-timer (in seconds) on the 620 AR-LEAF nodes is RECOMMENDED. Upon receiving a new Replicator-AR 621 route where the AR-REPLICATOR is selected, the AR-LEAF will run a 622 timer before programming the new AR-REPLICATOR. This will give 623 the AR-REPLICATOR some time to program the AR-LEAF nodes before 624 the AR-LEAF sends BM traffic. 626 An AR-LEAF will follow a data path implementation compatible with the 627 following rules: 629 - The AR-LEAF nodes will build two flood-lists: 631 1. Flood-list #1 - composed of ACs and an AR-REPLICATOR-set of 632 overlay tunnels. The AR-REPLICATOR-set is defined as one or 633 more overlay tunnels to the AR-IP Addresses of the remote AR- 634 REPLICATOR(s) in the BD. The selection of more than one AR- 635 REPLICATOR is described in point d) above and it is a local 636 AR-LEAF decision. 638 2. Flood-list #2 - composed of ACs and overlay tunnels to the 639 remote IR-IP Addresses. 641 - When an AR-LEAF receives a BM packet on an AC, it will check the 642 AR-REPLICATOR-set: 644 o If the AR-REPLICATOR-set is empty, the AR-LEAF will send the 645 packet to flood-list #2. 647 o If the AR-REPLICATOR-set is NOT empty, the AR-LEAF will send 648 the packet to flood-list #1, where only one of the overlay 649 tunnels of the AR-REPLICATOR-set is used. 651 - When an AR-LEAF receives a BM packet on an overlay tunnel, will 652 forward the BM packet to its local ACs and never to an overlay 653 tunnel. This is the regular IR behavior described in [RFC7432]. 655 - AR-LEAF nodes process Unknown unicast traffic in the same way AR- 656 REPLICATORS do, as described in section Section 5.1. 658 5.3. RNVE procedures 660 RNVE (Regular Network Virtualization Edge node) is defined as an NVE/ 661 PE without AR-REPLICATOR or AR-LEAF capabilities that does IR as 662 described in [RFC7432]. The RNVE does not signal any AR role and is 663 unaware of the AR-REPLICATOR/LEAF roles in the BD. The RNVE will 664 ignore the Flags in the Regular-IR routes and will ignore the 665 Replicator-AR routes (due to an unknown tunnel type in the PTA) and 666 the Leaf-AD routes (due to the IP-address-specific route-target). 668 This role provides EVPN with the backwards compatibility required in 669 optimized-IR BDs. Figure 1 shows NVE2 as RNVE. 671 6. Selective Assisted-Replication (AR) Solution Description 673 Figure 1 is also used to describe the selective AR solution, however 674 in this section we consider NVE2 as one more AR-LEAF for BD-1. The 675 solution is called "selective" because a given AR-REPLICATOR MUST 676 replicate the BM traffic to only the AR-LEAF that requested the 677 replication (as opposed to all the AR-LEAF nodes) and MAY replicate 678 the BM traffic to the RNVEs. The same AR roles defined in Section 4 679 are used here, however the procedures are different. 681 The following sub-sections describe the differences in the procedures 682 of AR-REPLICATOR/LEAFs compared to the non-selective AR solution. 683 There is no change on the RNVEs. 685 6.1. Selective AR-REPLICATOR procedures 687 In our example in Figure 1, PE1 and PE2 are defined as Selective AR- 688 REPLICATORs. The following considerations apply to the Selective AR- 689 REPLICATOR role: 691 a. The Selective AR-REPLICATOR capability SHOULD be an 692 administrative choice in any NVE/PE that is part of an AR-enabled 693 BD, as the AR role itself. This administrative option MAY be 694 implemented as a system level option as opposed to as a per-BD 695 option. 697 b. Each AR-REPLICATOR will build a list of AR-REPLICATOR, AR-LEAF 698 and RNVE nodes. In spite of the 'Selective' administrative 699 option, an AR-REPLICATOR MUST NOT behave as a Selective AR- 700 REPLICATOR if at least one of the AR-REPLICATORs has the L flag 701 NOT set. If at least one AR-REPLICATOR sends a Replicator-AR 702 route with L=0 (in the BD context), the rest of the AR- 703 REPLICATORs will fall back to non-selective AR mode. 705 c. The Selective AR-REPLICATOR MUST follow the procedures described 706 in section Section 5.1, except for the following differences: 708 o The Replicator-AR route MUST include L=1 (Leaf Information 709 Required) in the Replicator-AR route. This flag is used by 710 the AR-REPLICATORs to advertise their 'selective' AR- 711 REPLICATOR capabilities. In addition, the AR-REPLICATOR auto- 712 configures its IP-address-specific import route-target as 713 described in section Section 4. 715 o The AR-REPLICATOR will build a 'selective' AR-LEAF-set with 716 the list of nodes that requested replication to its own AR-IP. 717 For instance, assuming NVE1 and NVE2 advertise a Leaf-AD route 718 with PE1's IP-address-specific route-target and NVE3 719 advertises a Leaf-AD route with PE2's IP-address-specific 720 route-target, PE1 MUST only add NVE1/NVE2 to its selective AR- 721 LEAF-set for BD-1, and exclude NVE3. 723 o When a node defined and operating as Selective AR-REPLICATOR 724 receives a packet on an overlay tunnel, it will do a tunnel 725 destination IP lookup and if the destination IP is the AR- 726 REPLICATOR AR-IP Address, the node MUST replicate the packet 727 to: 729 + local ACs 731 + overlay tunnels in the Selective AR-LEAF-set (excluding the 732 overlay tunnel to the source AR-LEAF). 734 + overlay tunnels to the RNVEs if the tunnel source IP is the 735 IR-IP of an AR-LEAF (in any other case, the AR-REPLICATOR 736 MUST NOT replicate the BM traffic to remote RNVEs). In 737 other words, only the first-hop selective AR-REPLICATOR 738 will replicate to all the RNVEs. 740 + overlay tunnels to the remote Selective AR-REPLICATORs if 741 the tunnel source IP is an IR-IP of its own AR-LEAF-set (in 742 any other case, the AR-REPLICATOR MUST NOT replicate the BM 743 traffic to remote AR-REPLICATORs), where the tunnel 744 destination IP is the AR-IP of the remote Selective AR- 745 REPLICATOR. The tunnel destination IP AR-IP will be an 746 indication for the remote Selective AR-REPLICATOR that the 747 packet needs further replication to its AR-LEAFs. 749 A Selective AR-REPLICATOR data path implementation will be compatible 750 with the following rules: 752 - The Selective AR-REPLICATORs will build two flood-lists: 754 1. Flood-list #1 - composed of ACs and overlay tunnels to the 755 remote nodes in the BD, always using the IR-IPs in the tunnel 756 destination IP addresses. Some of those overlay tunnels MAY 757 be flagged as non-BM receivers based on the BM flag received 758 from the remote nodes in the BD. 760 2. Flood-list #2 - composed of ACs, a Selective AR-LEAF-set and a 761 Selective AR-REPLICATOR-set, where: 763 + The Selective AR-LEAF-set is composed of the overlay 764 tunnels to the AR-LEAFs that advertise a Leaf-AD route for 765 the local AR-REPLICATOR. This set is updated with every 766 Leaf-AD route received/withdrawn from a new AR-LEAF. 768 + The Selective AR-REPLICATOR-set is composed of the overlay 769 tunnels to all the AR-REPLICATORs that send a Replicator-AR 770 route with L=1. The AR-IP addresses are used as tunnel 771 destination IP. 773 - When a Selective AR-REPLICATOR receives a BM packet on an AC, it 774 will forward the BM packet to its flood-list #1, skipping the non- 775 BM overlay tunnels. 777 - When a Selective AR-REPLICATOR receives a BM packet on an overlay 778 tunnel, it will check the destination and source IPs of the 779 underlay IP header and: 781 o If the destination IP matches its AR-IP and the source IP 782 matches an IP of its own Selective AR-LEAF-set, the AR- 783 REPLICATOR will forward the BM packet to its flood-list #2, as 784 long as the list of AR-REPLICATORs for the BD matches the 785 Selective AR-REPLICATOR-set. If the Selective AR-REPLICATOR- 786 set does not match the list of AR-REPLICATORs, the node reverts 787 back to non-selective mode and flood-list #1 is used. 789 o If the destination IP matches its AR-IP and the source IP does 790 not match any IP of its Selective AR-LEAF-set, the AR- 791 REPLICATOR will forward the BM packet to flood-list #2 but 792 skipping the AR-REPLICATOR-set. 794 o If the destination IP matches its IR-IP, the AR-REPLICATOR will 795 use flood-list #1 but MUST skip all the overlay tunnels from 796 the flooding list, i.e. it will only replicate to local ACs. 797 This is the regular-IR behavior described in [RFC7432]. 799 - In any case, non-BM overlay tunnels are excluded from flood-lists 800 and, also, source squelching is always done in order to ensure the 801 traffic is not sent back to the originating source. If the 802 encapsulation is MPLSoGRE (or MPLSoUDP) and the BD label is not 803 the bottom of the stack, the AR-REPLICATOR MUST copy the rest of 804 the labels when forwarding them to the egress overlay tunnels. 806 6.2. Selective AR-LEAF procedures 808 A Selective AR-LEAF chooses a single Selective AR-REPLICATOR per BD 809 and: 811 - Sends all the BD BM traffic to that AR-REPLICATOR and 812 - Expects to receive the BM traffic for a given BD from the same AR- 813 REPLICATOR. 815 In the example of Figure 1, we consider NVE1/NVE2/NVE3 as Selective 816 AR-LEAFs. NVE1 selects PE1 as its Selective AR-REPLICATOR. If that 817 is so, NVE1 will send all its BM traffic for BD-1 to PE1. If other 818 AR-LEAF/REPLICATORs send BM traffic, NVE1 will receive that traffic 819 from PE1. These are the differences in the behavior of a Selective 820 AR-LEAF compared to a non-selective AR-LEAF: 822 a. The AR-LEAF role selective capability SHOULD be an administrative 823 choice in any NVE/PE that is part of an AR-enabled BD. This 824 administrative option to enable AR-LEAF capabilities MAY be 825 implemented as a system level option as opposed to as per-BD 826 option. 828 b. The AR-LEAF MAY advertise a Regular-IR route if there are RNVEs 829 in the BD. The Selective AR-LEAF MUST advertise a Leaf-AD route 830 after receiving a Replicator-AR route with L=1. It is 831 RECOMMENDED that the Selective AR-LEAF waits for a timer t before 832 sending the Leaf-AD route, so that the AR-LEAF receives all the 833 Replicator-AR routes for the BD. 835 c. In a service where there is more than one Selective AR- 836 REPLICATORs the Selective AR-LEAF MUST locally select a single 837 Selective AR-REPLICATOR for the BD. Once selected: 839 o The Selective AR-LEAF will send a Leaf-AD route including the 840 Route-key and IP-address-specific route-target of the selected 841 AR-REPLICATOR. 843 o The Selective AR-LEAF will send all the BM packets received on 844 the attachment circuits (ACs) for a given BD to that AR- 845 REPLICATOR. 847 o In case of a failure on the selected AR-REPLICATOR, another 848 AR-REPLICATOR will be selected and a new Leaf-AD update will 849 be issued for the new AR-REPLICATOR. This new route will 850 update the selective list in the new Selective AR-REPLICATOR. 851 In case of failure on the active Selective AR-REPLICATOR, it 852 is RECOMMENDED for the Selective AR-LEAF to revert to IR 853 behavior for a timer t to speed up the convergence. When the 854 timer expires, the Selective AR-LEAF will resume its AR mode 855 with the new Selective AR-REPLICATOR. 857 All the AR-LEAFs in a BD are expected to be configured as either 858 selective or non-selective. A mix of selective and non-selective AR- 859 LEAFs SHOULD NOT coexist in the same BD. In case there is a non- 860 selective AR-LEAF, its BM traffic sent to a selective AR-REPLICATOR 861 will not be replicated to other AR-LEAFs that are not in its 862 Selective AR-LEAF-set. 864 A Selective AR-LEAF will follow a data path implementation compatible 865 with the following rules: 867 - The Selective AR-LEAF nodes will build two flood-lists: 869 1. Flood-list #1 - composed of ACs and the overlay tunnel to the 870 selected AR-REPLICATOR (using the AR-IP as the tunnel 871 destination IP). 873 2. Flood-list #2 - composed of ACs and overlay tunnels to the 874 remote IR-IP Addresses. 876 - When an AR-LEAF receives a BM packet on an AC, it will check if 877 there is any selected AR-REPLICATOR. If there is, flood-list #1 878 will be used. Otherwise, flood-list #2 will. 880 - When an AR-LEAF receives a BM packet on an overlay tunnel, will 881 forward the BM packet to its local ACs and never to an overlay 882 tunnel. This is the regular IR behavior described in [RFC7432]. 884 7. Pruned-Flood-Lists (PFL) 886 In addition to AR, the second optimization supported by this solution 887 is the ability for the all the BD nodes to signal Pruned-Flood-Lists 888 (PFL). As described in section 3, an EVPN node can signal a given 889 value for the BM and U PFL flags in the IR Inclusive Multicast 890 Routes, where: 892 - BM= Broadcast and Multicast (BM) flag. BM=1 means "prune-me" from 893 the BM flood-list. BM=0 means regular behavior. 895 - U= Unknown flag. U=1 means "prune-me" from the Unknown flood- 896 list. U=0 means regular behavior. 898 The ability to signal these PFL flags is an administrative choice. 899 Upon receiving a non-zero PFL flag, a node MAY decide to honor the 900 PFL flag and remove the sender from the corresponding flood-list. A 901 given BD node receiving BUM traffic on an overlay tunnel MUST 902 replicate the traffic normally, regardless of the signaled PFL flags. 904 This optimization MAY be used along with the AR solution. 906 7.1. A PFL example 908 In order to illustrate the use of the solution described in this 909 document, we will assume that BD-1 in figure 1 is optimized-IR 910 enabled and: 912 - PE1 and PE2 are administratively configured as AR-REPLICATORs, due 913 to their high-performance replication capabilities. PE1 and PE2 914 will send a Replicator-AR route with BM/U flags = 00. 916 - NVE1 and NVE3 are administratively configured as AR-LEAF nodes, 917 due to their low-performance software-based replication 918 capabilities. They will advertise a Regular-IR route with type 919 AR-LEAF. Assuming both NVEs advertise all the attached VMs in 920 EVPN as soon as they come up and don't have any VMs interested in 921 multicast applications, they will be configured to signal BM/U 922 flags = 11 for BD-1. 924 - NVE2 is optimized-IR unaware; therefore it takes on the RNVE role 925 in BD-1. 927 Based on the above assumptions the following forwarding behavior will 928 take place: 930 1. Any BM packets sent from VM11 will be sent to VM12 and PE1. PE1 931 will forward further the BM packets to TS1, WAN link, PE2 and 932 NVE2, but not to NVE3. PE2 and NVE2 will replicate the BM 933 packets to their local ACs but we will avoid NVE3 having to 934 replicate unnecessarily those BM packets to VM31 and VM32. 936 2. Any BM packets received on PE2 from the WAN will be sent to PE1 937 and NVE2, but not to NVE1 and NVE3, sparing the two hypervisors 938 from replicating unnecessarily to their local VMs. PE1 and NVE2 939 will replicate to their local ACs only. 941 3. Any Unknown unicast packet sent from VM31 will be forwarded by 942 NVE3 to NVE2, PE1 and PE2 but not NVE1. The solution avoids the 943 unnecessary replication to NVE1, since the destination of the 944 unknown traffic cannot be at NVE1. 946 4. Any Unknown unicast packet sent from TS1 will be forwarded by PE1 947 to the WAN link, PE2 and NVE2 but not to NVE1 and NVE3, since the 948 target of the unknown traffic cannot be at those NVEs. 950 8. AR Procedures for single-IP AR-REPLICATORS 952 The procedures explained in sections Section 5 and Section 6 assume 953 that the AR-REPLICATOR can use two local routable IP addresses to 954 terminate and originate NVO tunnels, i.e. IR-IP and AR-IP addresses. 955 This is usually the case for PE-based AR-REPLICATOR nodes. 957 In some cases, the AR-REPLICATOR node does not support more than one 958 IP address to terminate and originate NVO tunnels, i.e. the IR-IP and 959 AR-IP are the same IP addresses. This may be the case in some 960 software-based or low-end AR-REPLICATOR nodes. If this is the case, 961 the procedures in sections Section 5 and Section 6 MUST be modified 962 in the following way: 964 - The Replicator-AR routes generated by the AR-REPLICATOR use an AR- 965 IP that will match its IR-IP. In order to differentiate the data 966 plane packets that need to use IR from the packets that must use 967 AR forwarding mode, the Replicator-AR route MUST advertise a 968 different VNI/VSID than the one used by the Regular-IR route. For 969 instance, the AR-REPLICATOR will advertise AR-VNI along with the 970 Replicator-AR route and IR-VNI along with the Regular-IR route. 971 Since both routes have the same key, different RDs are needed in 972 each route. 974 - An AR-REPLICATOR will perform IR or AR forwarding mode for the 975 incoming Overlay packets based on an ingress VNI lookup, as 976 opposed to the tunnel IP DA lookup. Note that, when replicating 977 to remote AR-REPLICATOR nodes, the use of the IR-VNI or AR-VNI 978 advertised by the egress node will determine the IR or AR 979 forwarding mode at the subsequent AR-REPLICATOR. 981 The rest of the procedures will follow what is described in sections 982 Section 5 and Section 6. 984 9. AR Procedures and EVPN All-Active Multi-homing Split-Horizon 986 This section extends the procedures for the cases where AR-LEAF nodes 987 or AR-REPLICATOR nodes are attached to the the same Ethernet Segment 988 in the BD. The case where one (or more) AR-LEAF node(s) and one (or 989 more) AR-REPLICATOR node(s) are attached to the same Ethernet Segment 990 is out of scope. 992 9.1. Ethernet Segments on AR-LEAF nodes 994 If VXLAN or NVGRE are used, and if the Split-horizon is based on the 995 tunnel IP SA and "Local-Bias" as described in [RFC8365], the Split- 996 horizon check will not work if there is an Ethernet-Segment shared 997 between two AR-LEAF nodes, and the AR-REPLICATOR changes the tunnel 998 IP SA of the packets with its own AR-IP. 1000 In order to be compatible with the IP SA split-horizon check, the AR- 1001 REPLICATOR MAY keep the original received tunnel IP SA when 1002 replicating packets to a remote AR-LEAF or RNVE. This will allow AR- 1003 LEAF nodes to apply Split-horizon check procedures for BM packets, 1004 before sending them to the local Ethernet-Segment. Even if the AR- 1005 LEAF's IP SA is preserved when replicating to AR-LEAFs or RNVEs, the 1006 AR-REPLICATOR MUST always use its IR-IP as IP SA when replicating to 1007 other AR-REPLICATORs. 1009 When EVPN is used for MPLS over GRE (or UDP), the ESI-label based 1010 split-horizon procedure as in [RFC7432] will not work for multi-homed 1011 Ethernet-Segments defined on AR-LEAF nodes. "Local-Bias" is 1012 recommended in this case, as in the case of VXLAN or NVGRE explained 1013 above. The "Local-Bias" and tunnel IP SA preservation mechanisms 1014 provide the required split-horizon behavior in non-selective or 1015 selective AR. 1017 Note that if the AR-REPLICATOR implementation keeps the received 1018 tunnel IP SA, the use of uRPF (unicast Reverse Path Forwarding) 1019 checks in the IP fabric based on the tunnel IP SA MUST be disabled. 1021 9.2. Ethernet Segments on AR-REPLICATOR nodes 1023 Ethernet Segments associated to one or more AR-REPLICATOR nodes 1024 SHOULD follow "Local-Bias" procedures for EVPN all-active multi- 1025 homing, as follows: 1027 - For BUM traffic received on a local AR-REPLICATOR's AC, "Local- 1028 Bias" procedures as in [RFC8365] SHOULD be followed. 1030 - For BUM traffic received on an AR-REPLICATOR overlay tunnel with 1031 AR-IP as the IP DA, "Local-Bias" SHOULD also be followed. That 1032 is, traffic received with AR-IP as IP DA will be treated as though 1033 it had been received on a local AC that is part of the ES and will 1034 be forwarded to all local ES, irrespective of their DF or NDF 1035 state. 1037 - BUM traffic received on an AR-REPLICATOR overlay tunnel with IR-IP 1038 as the IP DA, will follow regular [RFC8365] "Local-Bias" rules and 1039 will not be forwarded to local ESes that are shared with the AR- 1040 LEF or AR-REPLICATOR originating the traffic. 1042 10. Security Considerations 1044 The Security Considerations in [RFC7432] and [RFC8365] apply to this 1045 document. 1047 In addition, the procedures introduced by this document may bring 1048 some new risks for the successful delivery of BM traffic. Unicast 1049 traffic is not affected by this document. The forwarding of 1050 Broadcast and Multicast (BM) traffic is modified though, and BM 1051 traffic from the AR-LEAF nodes will be attracted by the existance of 1052 AR-REPLICATORs in the BD. An AR-LEAF will forward BM traffic to its 1053 selected AR-REPLICATOR, therefore an attack on the AR-REPLICATOR 1054 could impact the delivery of the BM traffic using that node. 1056 A implementation following the procedures in this document should not 1057 create BM loops, since the AR-REPLICATOR will always forward the BM 1058 traffic using the correct tunnel IP Destination Address that 1059 indicates the remote nodes how to forward the traffic. This is true 1060 in both, the Non-Selective and Selective modes defined in this 1061 document. 1063 The Selective mode provides a multi-staged replication solution, 1064 where a proper configuration of all the AR-REPLICATORs will avoid any 1065 issues. A mix of mistakenly configured Selective and Non-Selective 1066 AR-REPLICATORs in the same BD could theoretically create packet 1067 duplication in some AR-LEAFs, however this document provides a fall 1068 back solution to Non-Selective mode in case the AR-REPLICATORs 1069 advertised an inconsistent AR Replication mode. 1071 Finally, the use of PFL as in Section 7, should be handled with care. 1072 An intentional or unintentional misconfiguration of the BDs on a 1073 given leaf node may result in the leaf not receiving the required BM 1074 or Unknown unicast traffic. 1076 11. IANA Considerations 1078 IANA has allocated the following Border Gateway Protocol (BGP) 1079 Parameters: 1081 - Allocation in the P-Multicast Service Interface Tunnel (PMSI 1082 Tunnel) Tunnel Types registry: 1084 Value Meaning Reference 1085 0x0A Assisted-Replication Tunnel [This document] 1087 - Allocations in the P-Multicast Service Interface (PMSI) Tunnel 1088 Attribute Flags registry: 1090 Value Name Reference 1091 3-4 Assisted-Replication Type (T) [This document] 1092 5 Broadcast and Multicast (BM) [This document] 1093 6 Unknown (U) [This document] 1095 12. Contributors 1097 In addition to the names in the front page, the following co-authors 1098 also contributed to this document: 1100 Wim Henderickx 1101 Nokia 1103 Kiran Nagaraj 1104 Nokia 1106 Ravi Shekhar 1107 Juniper Networks 1109 Nischal Sheth 1110 Juniper Networks 1112 Aldrin Isaac 1113 Juniper 1115 Mudassir Tufail 1116 Citibank 1118 13. Acknowledgments 1120 The authors would like to thank Neil Hart, David Motz, Dai Truong, 1121 Thomas Morin, Jeffrey Zhang, Shankar Murthy and Krzysztof Szarkowicz 1122 for their valuable feedback and contributions. 1124 14. References 1126 14.1. Normative References 1128 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1129 Requirement Levels", BCP 14, RFC 2119, 1130 DOI 10.17487/RFC2119, March 1997, 1131 . 1133 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1134 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1135 May 2017, . 1137 [RFC6514] Aggarwal, R., Rosen, E., Morin, T., and Y. Rekhter, "BGP 1138 Encodings and Procedures for Multicast in MPLS/BGP IP 1139 VPNs", RFC 6514, DOI 10.17487/RFC6514, February 2012, 1140 . 1142 [RFC7432] Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A., 1143 Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based 1144 Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432, February 1145 2015, . 1147 [I-D.ietf-bess-evpn-bum-procedure-updates] 1148 Zhang, Z., Lin, W., Rabadan, J., Patel, K., and A. 1149 Sajassi, "Updates on EVPN BUM Procedures", draft-ietf- 1150 bess-evpn-bum-procedure-updates-08 (work in progress), 1151 November 2019. 1153 14.2. Informative References 1155 [RFC8365] Sajassi, A., Ed., Drake, J., Ed., Bitar, N., Shekhar, R., 1156 Uttaro, J., and W. Henderickx, "A Network Virtualization 1157 Overlay Solution Using Ethernet VPN (EVPN)", RFC 8365, 1158 DOI 10.17487/RFC8365, March 2018, 1159 . 1161 Authors' Addresses 1163 J. Rabadan (editor) 1164 Nokia 1165 777 Middlefield Road 1166 Mountain View, CA 94043 1167 USA 1169 Email: jorge.rabadan@nokia.com 1171 S. Sathappan 1172 Nokia 1174 Email: senthil.sathappan@nokia.com 1175 W. Lin 1176 Juniper Networks 1178 Email: wlin@juniper.net 1180 M. Katiyar 1181 Versa Networks 1183 Email: mukul@versa-networks.com 1185 A. Sajassi 1186 Cisco Systems 1188 Email: sajassi@cisco.com