idnits 2.17.1 draft-ietf-bess-evpn-optimized-ir-02.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 : ---------------------------------------------------------------------------- ** The document seems to lack an Introduction section. ** There are 2 instances of lines with control characters in the document. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == Using lowercase 'not' together with uppercase 'MUST', 'SHALL', 'SHOULD', or 'RECOMMENDED' is not an accepted usage according to RFC 2119. Please use uppercase 'NOT' together with RFC 2119 keywords (if that is what you mean). Found 'MUST not' in this paragraph: o AR-LEAF nodes SHALL send service-level BM control plane packets following regular IR procedures. An example would be IGMP, MLD or PIM multicast packets. The AR-REPLICATORs MUST not replicate these control plane packets to other overlay tunnels since they will use the regular IR-IP Address. -- The document date (August 16, 2017) is 2416 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) == Missing Reference: 'RFC7432' is mentioned on line 1033, but not defined == Missing Reference: 'RFC6514' is mentioned on line 254, but not defined == Missing Reference: 'RFC2119' is mentioned on line 976, but not defined == Outdated reference: A later version (-14) exists of draft-ietf-bess-evpn-bum-procedure-updates-01 == Outdated reference: A later version (-12) exists of draft-ietf-bess-evpn-overlay-07 Summary: 2 errors (**), 0 flaws (~~), 7 warnings (==), 1 comment (--).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 W. Henderickx 5 Nokia 6 R. Shekhar 7 N. Sheth A. Sajassi 8 W. Lin Cisco 9 M. Katiyar 10 Juniper A. Isaac 11 Juniper 12 M. Tufail 13 Citibank 15 Expires: February 17, 2018 August 16, 2017 17 Optimized Ingress Replication solution for EVPN 18 draft-ietf-bess-evpn-optimized-ir-02 20 Abstract 22 Network Virtualization Overlay (NVO) networks using EVPN as control 23 plane may use ingress replication (IR) or PIM-based trees to convey 24 the overlay BUM traffic. PIM provides an efficient solution to avoid 25 sending multiple copies of the same packet over the same physical 26 link, however it may not always be deployed in the NVO core network. 27 IR avoids the dependency on PIM in the NVO network core. While IR 28 provides a simple multicast transport, some NVO networks with 29 demanding multicast applications require a more efficient solution 30 without PIM in the core. This document describes a solution to 31 optimize the efficiency of IR in NVO networks. 33 Status of this Memo 35 This Internet-Draft is submitted in full conformance with the 36 provisions of BCP 78 and BCP 79. 38 Internet-Drafts are working documents of the Internet Engineering 39 Task Force (IETF), its areas, and its working groups. Note that 40 other groups may also distribute working documents as Internet- 41 Drafts. 43 Internet-Drafts are draft documents valid for a maximum of six months 44 and may be updated, replaced, or obsoleted by other documents at any 45 time. It is inappropriate to use Internet-Drafts as reference 46 material or to cite them other than as "work in progress." 48 The list of current Internet-Drafts can be accessed at 49 http://www.ietf.org/ietf/1id-abstracts.txt 51 The list of Internet-Draft Shadow Directories can be accessed at 52 http://www.ietf.org/shadow.html 54 This Internet-Draft will expire on February 17, 2018. 56 Copyright Notice 58 Copyright (c) 2017 IETF Trust and the persons identified as the 59 document authors. All rights reserved. 61 This document is subject to BCP 78 and the IETF Trust's Legal 62 Provisions Relating to IETF Documents 63 (http://trustee.ietf.org/license-info) in effect on the date of 64 publication of this document. Please review these documents 65 carefully, as they describe your rights and restrictions with respect 66 to this document. Code Components extracted from this document must 67 include Simplified BSD License text as described in Section 4.e of 68 the Trust Legal Provisions and are provided without warranty as 69 described in the Simplified BSD License. 71 Table of Contents 73 1. Problem Statement . . . . . . . . . . . . . . . . . . . . . . . 3 74 2. Solution requirements . . . . . . . . . . . . . . . . . . . . . 4 75 3. EVPN BGP Attributes for optimized-IR . . . . . . . . . . . . . 5 76 4. Non-selective Assisted-Replication (AR) Solution Description . 7 77 4.1. Non-selective AR-REPLICATOR procedures . . . . . . . . . . 8 78 4.2. Non-selective AR-LEAF procedures . . . . . . . . . . . . . 9 79 4.3. RNVE procedures . . . . . . . . . . . . . . . . . . . . . . 11 80 4.4. Forwarding behavior in non-selective AR EVIs . . . . . . . 11 81 4.4.1. Broadcast and Multicast forwarding behavior . . . . . . 11 82 4.4.1.1. Non-selective AR-REPLICATOR BM forwarding . . . . . 11 83 4.4.1.2. Non-selective AR-LEAF BM forwarding . . . . . . . . 12 84 4.4.1.3. RNVE BM forwarding . . . . . . . . . . . . . . . . 12 85 4.4.2. Unknown unicast forwarding behavior . . . . . . . . . . 13 86 4.4.2.1. Non-selective AR-REPLICATOR/LEAF Unknown unicast 87 forwarding . . . . . . . . . . . . . . . . . . . . 13 88 4.4.2.2. RNVE Unknown unicast forwarding . . . . . . . . . . 13 89 5. Selective Assisted-Replication (AR) Solution Description . . . 13 90 5.1. Selective AR-REPLICATOR procedures . . . . . . . . . . . . 14 91 5.2. Selective AR-LEAF procedures . . . . . . . . . . . . . . . 15 92 5.3. Forwarding behavior in selective AR EVIs . . . . . . . . . 16 93 5.3.1. Selective AR-REPLICATOR BM forwarding . . . . . . . . . 16 94 5.3.2. Selective AR-LEAF BM forwarding . . . . . . . . . . . . 17 95 6. Pruned-Flood-Lists (PFL) . . . . . . . . . . . . . . . . . . . 18 96 6.1. A PFL example . . . . . . . . . . . . . . . . . . . . . . . 18 97 7. AR Procedures for single-IP AR-REPLICATORS . . . . . . . . . . 19 98 8. AR Procedures and EVPN Multi-homing Split-Horizon . . . . . . . 20 99 9. Out-of-band distribution of Broadcast/Multicast traffic . . . . 21 100 10. Benefits of the optimized-IR solution . . . . . . . . . . . . 21 101 11. Conventions used in this document . . . . . . . . . . . . . . 21 102 12. Security Considerations . . . . . . . . . . . . . . . . . . . 21 103 13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22 104 14. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 22 105 15. References . . . . . . . . . . . . . . . . . . . . . . . . . . 23 106 15.1 Normative References . . . . . . . . . . . . . . . . . . . 23 107 15.2 Informative References . . . . . . . . . . . . . . . . . . 23 108 16. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 23 109 17. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 23 111 1. Problem Statement 113 EVPN may be used as the control plane for a Network Virtualization 114 Overlay (NVO) network. Network Virtualization Edge (NVE) devices and 115 PEs that are part of the same EVI use Ingress Replication (IR) or 116 PIM-based trees to transport the tenant's BUM traffic. In NVO 117 networks where PIM-based trees cannot be used, IR is the only 118 alternative. Examples of these situations are NVO networks where the 119 core nodes don't support PIM or the network operator does not want to 120 run PIM in the core. 122 In some use-cases, the amount of replication for BUM (Broadcast, 123 Unknown unicast and Multicast traffic) is kept under control on the 124 NVEs due to the following fairly common assumptions: 126 a) Broadcast is greatly reduced due to the proxy-ARP and proxy-ND 127 capabilities supported by EVPN on the NVEs. Some NVEs can even 128 provide DHCP-server functions for the attached Tenant Systems (TS) 129 reducing the broadcast even further. 131 b) Unknown unicast traffic is greatly reduced in virtualized NVO 132 networks where all the MAC and IP addresses are learnt in the 133 control plane. 135 c) Multicast applications are not used. 137 If the above assumptions are true for a given NVO network, then IR 138 provides a simple solution for multi-destination traffic. However, 139 the statement c) above is not always true and multicast applications 140 are required in many use-cases. 142 When the multicast sources are attached to NVEs residing in 143 hypervisors or low-performance-replication TORs, the ingress 144 replication of a large amount of multicast traffic to a significant 145 number of remote NVEs/PEs can seriously degrade the performance of 146 the NVE and impact the application. 148 This document describes a solution that makes use of two IR 149 optimizations: 151 i) Assisted-Replication (AR) 152 ii) Pruned-Flood-Lists (PFL) 154 Both optimizations may be used together or independently so that the 155 performance and efficiency of the network to transport multicast can 156 be improved. Both solutions require some extensions to [RFC7432] that 157 are described in section 3. 159 Section 2 lists the requirements of the combined optimized-IR 160 solution, whereas sections 4 and 5 describe the Assisted-Replication 161 (AR) solution, and section 6 the Pruned-Flood-Lists (PFL) solution. 163 2. Solution requirements 165 The IR optimization solution (optimized-IR hereafter) MUST meet the 166 following requirements: 168 a) The solution MUST provide an IR optimization for BM (Broadcast and 169 Multicast) traffic, while preserving the packet order for unicast 170 applications, i.e. known and unknown unicast traffic SHALL follow 171 the same path. 173 b) The solution MUST be compatible with [RFC7432] and [EVPN-OVERLAY] 174 and have no impact on the EVPN procedures for BM traffic. In 175 particular, the solution SHOULD support the following EVPN 176 functions: 178 o All-active multi-homing, including the split-horizon and 179 Designated Forwarder (DF) functions. 181 o Single-active multi-homing, including the DF function. 183 o Handling of multi-destination traffic and processing of 184 broadcast and multicast as per [RFC7432]. 186 c) The solution MUST be backwards compatible with existing NVEs using 187 a non-optimized version of IR. A given EVI can have NVEs/PEs 188 supporting regular-IR and optimized-IR. 190 d) The solution MUST be independent of the NVO specific data plane 191 encapsulation and the virtual identifiers being used, e.g.: VXLAN 192 VNIs, NVGRE VSIDs or MPLS labels. 194 3. EVPN BGP Attributes for optimized-IR 196 This solution proposes some changes to the [RFC7432] Inclusive 197 Multicast Ethernet Tag routes and attributes so that an NVE/PE can 198 signal its optimized-IR capabilities. 200 The Inclusive Multicast Ethernet Tag route (RT-3) and its PMSI Tunnel 201 Attribute's (PTA) general format used in [RFC7432] are shown below: 203 +---------------------------------+ 204 | RD (8 octets) | 205 +---------------------------------+ 206 | Ethernet Tag ID (4 octets) | 207 +---------------------------------+ 208 | IP Address Length (1 octet) | 209 +---------------------------------+ 210 | Originating Router's IP Addr | 211 | (4 or 16 octets) | 212 +---------------------------------+ 214 +---------------------------------+ 215 | Flags (1 octet) | 216 +---------------------------------+ 217 | Tunnel Type (1 octets) | 218 +---------------------------------+ 219 | MPLS Label (3 octets) | 220 +---------------------------------+ 221 | Tunnel Identifier (variable) | 222 +---------------------------------+ 224 The Flags field is defined as follows: 226 0 1 2 3 4 5 6 7 227 +-+-+-+-+-+--+-+-+ 228 |rsved| T |BM|U|L| 229 +-+-+-+-+-+--+-+-+ 231 Where a new type field (for AR) and two new flags (for PFL signaling) 232 are defined: 234 - T is the AR Type field (2 bits) that defines the AR role of the 235 advertising router: 237 + 00 (decimal 0) = RNVE (non-AR support) 239 + 01 (decimal 1) = AR-REPLICATOR 241 + 10 (decimal 2) = AR-LEAF 243 + 11 (decimal 3) = RESERVED 245 - The PFL (Pruned-Flood-Lists) flags defined the desired behavior of 246 the advertising router for the different types of traffic: 248 + BM= Broadcast and Multicast (BM) flag. BM=1 means "prune-me" from 249 the BM flooding list. BM=0 means regular behavior. 251 + U= Unknown flag. U=1 means "prune-me" from the Unknown flooding 252 list. U=0 means regular behavior. 254 - Flag L is an existing flag defined in [RFC6514] (L=Leaf Information 255 Required) and it will be used only in the Selective AR Solution. 257 Please refer to section 10 for the IANA considerations related to the 258 PTA flags. 260 In this document, the above RT-3 and PTA can be used in two different 261 modes for the same EVI/Ethernet Tag: 263 o Regular-IR route: in this route, Originating Router's IP Address, 264 Tunnel Type (0x06), MPLS Label, Tunnel Identifier and Flags MUST be 265 used as described in [RFC7432]. The Originating Router's IP Address 266 and Tunnel Identifier are set to an IP address that we denominate 267 IR-IP in this document. 269 o Replicator-AR route: this route is used by the AR-REPLICATOR to 270 advertise its AR capabilities, with the fields set as follows. 272 + Originating Router's IP Address as well as the Tunnel Identifier 273 are set to the same routable IP address that we denominate AR-IP 274 and SHOULD be different than the IR-IP for a given PE/NVE. 276 + Tunnel Type = Assisted-Replication (AR). Section 11 provides the 277 allocated type value. 279 + T (AR role type) = 01 (AR-REPLICATOR). 281 + L (Leaf Information Required) = 0 (for non-selective AR) or 1 282 (for selective AR). 284 In addition, this document also uses the Leaf-AD route (RT-11) 285 defined in [EVPN-BUM] in case the selective AR mode is used. The 286 Leaf-AD route MAY be used by the AR-LEAF in response to a Replicator- 287 AR route (with the L flag set) to advertise its desire to receive the 288 multicast traffic from a specific AR-REPLICATOR. It is only used for 289 selective AR and its fields are set as follows: 291 + Originating Router's IP Address is set to the advertising IR-IP 292 (same IP used by the AR-LEAF in regular-IR routes). 294 + Route Key is the "Route Type Specific" NLRI of the Replicator-AR 295 route for which this Leaf-AD route is generated. 297 + The AR-LEAF constructs an IP-address-specific route-target as 298 indicated in [EVPN-BUM], by placing the IP address carried in the 299 Next Hop field of the received Replicator-AR route in the Global 300 Administrator field of the Community, with the Local 301 Administrator field of this Community set to 0. Note that the 302 same IP-address-specific import route-target is auto-configured 303 by the AR-REPLICATOR that sent the Replicator-AR, in order to 304 control the acceptance of the Leaf-AD routes. 306 + The leaf-AD route MUST include the PMSI Tunnel attribute with the 307 Tunnel Type set to AR, type set to AR-LEAF and the Tunnel 308 Identifier set to the IR-IP of the advertising AR-LEAF. The PMSI 309 Tunnel attribute MUST carry a downstream-assigned MPLS label that 310 is used by the AR-REPLICATOR to send traffic to the AR-LEAF. 312 Each AR-enabled node MUST understand and process the AR type field in 313 the PTA (Flags field) of the routes, and MUST signal the 314 corresponding type (1 or 2) according to its administrative choice. 316 Each node, part of the EVI, MAY understand and process the BM/U 317 flags. Note that these BM/U flags may be used to optimize the 318 delivery of multi-destination traffic and its use SHOULD be an 319 administrative choice, and independent of the AR role. 321 Non-optimized-IR nodes will be unaware of the new PMSI attribute flag 322 definition as well as the new Tunnel Type (AR), i.e. they will ignore 323 the information contained in the flags field for any RT-3 and will 324 ignore the RT-3 routes with an unknown Tunnel Type (type AR in this 325 case). 327 4. Non-selective Assisted-Replication (AR) Solution Description 328 The following figure illustrates an example NVO network where the 329 non-selective AR function is enabled. Three different roles are 330 defined for a given EVI: AR-REPLICATOR, AR-LEAF and RNVE (Regular 331 NVE). The solution is called "non-selective" because the chosen AR- 332 REPLICATOR for a given flow MUST replicate the multicast traffic to 333 'all' the NVE/PEs in the EVI except for the source NVE/PE. 335 ( ) 336 (_ WAN _) 337 +---(_ _)----+ 338 | (_ _) | 339 PE1 | PE2 | 340 +------+----+ +----+------+ 341 TS1--+ (EVI-1) | | (EVI-1) +--TS2 342 |REPLICATOR | |REPLICATOR | 343 +--------+--+ +--+--------+ 344 | | 345 +--+----------------+--+ 346 | | 347 | | 348 +----+ VXLAN/nvGRE/MPLSoGRE +----+ 349 | | IP Fabric | | 350 | | | | 351 NVE1 | +-----------+----------+ | NVE3 352 Hypervisor| TOR | NVE2 |Hypervisor 353 +---------+-+ +-----+-----+ +-+---------+ 354 | (EVI-1) | | (EVI-1) | | (EVI-1) | 355 | LEAF | | RNVE | | LEAF | 356 +--+-----+--+ +--+-----+--+ +--+-----+--+ 357 | | | | | | 358 VM11 VM12 TS3 TS4 VM31 VM32 360 Figure 1 Optimized-IR scenario 362 4.1. Non-selective AR-REPLICATOR procedures 364 An AR-REPLICATOR is defined as an NVE/PE capable of replicating 365 ingress BM (Broadcast and Multicast) traffic received on an overlay 366 tunnel to other overlay tunnels and local Attachment Circuits (ACs). 367 The AR-REPLICATOR signals its role in the control plane and 368 understands where the other roles (AR-LEAF nodes, RNVEs and other AR- 369 REPLICATORs) are located. A given AR-enabled EVI service may have 370 zero, one or more AR-REPLICATORs. In our example in figure 1, PE1 and 371 PE2 are defined as AR-REPLICATORs. The following considerations apply 372 to the AR-REPLICATOR role: 374 a) The AR-REPLICATOR role SHOULD be an administrative choice in any 375 NVE/PE that is part of an AR-enabled EVI. This administrative 376 option to enable AR-REPLICATOR capabilities MAY be implemented as 377 a system level option as opposed to as a per-MAC-VRF option. 379 b) An AR-REPLICATOR MUST advertise a Replicator-AR route and MAY 380 advertise a Regular-IR route. The AR-REPLICATOR MUST NOT generate 381 a Regular-IR route if it does not have local attachment circuits 382 (AC). 384 c) The Replicator-AR and Regular-IR routes will be generated 385 according to section 3. The AR-IP and IR-IP used by the 386 Replicator-AR will be different routable IP addresses. 388 d) When a node defined as AR-REPLICATOR receives a packet on an 389 overlay tunnel, it will do a tunnel destination IP lookup and 390 apply the following procedures: 392 o If the destination IP is the AR-REPLICATOR IR-IP Address the 393 node will process the packet normally as in [RFC7432]. 395 o If the destination IP is the AR-REPLICATOR AR-IP Address the 396 node MUST replicate the packet to local ACs and overlay 397 tunnels (excluding the overlay tunnel to the source of the 398 packet). When replicating to remote AR-REPLICATORs the tunnel 399 destination IP will be an IR-IP. That will be an indication 400 for the remote AR-REPLICATOR that it MUST NOT replicate to 401 overlay tunnels. The tunnel source IP will be the AR-IP of the 402 AR-REPLICATOR. 404 4.2. Non-selective AR-LEAF procedures 406 AR-LEAF is defined as an NVE/PE that - given its poor replication 407 performance - sends all the BM traffic to an AR-REPLICATOR that can 408 replicate the traffic further on its behalf. It MAY signal its AR- 409 LEAF capability in the control plane and understands where the other 410 roles are located (AR-REPLICATOR and RNVEs). A given service can have 411 zero, one or more AR-LEAF nodes. Figure 1 shows NVE1 and NVE3 (both 412 residing in hypervisors) acting as AR-LEAF. The following 413 considerations apply to the AR-LEAF role: 415 a) The AR-LEAF role SHOULD be an administrative choice in any NVE/PE 416 that is part of an AR-enabled EVI. This administrative option to 417 enable AR-LEAF capabilities MAY be implemented as a system level 418 option as opposed to as per-MAC-VRF option. 420 b) In this non-selective AR solution, the AR-LEAF MUST advertise a 421 single Regular-IR inclusive multicast route as in [RFC7432]. The 422 AR-LEAF SHOULD set the AR Type field to AR-LEAF. Note that 423 although this flag does not make any difference for the egress 424 nodes when creating an EVPN destination to the the AR-LEAF, it is 425 RECOMMENDED the use of this flag for an easy operation and 426 troubleshooting of the EVI. 428 c) In a service where there are no AR-REPLICATORs, the AR-LEAF MUST 429 use regular ingress replication. This will happen when a new 430 update from the last former AR-REPLICATOR is received and contains 431 a non-REPLICATOR AR type, or when the AR-LEAF detects that the 432 last AR-REPLICATOR is down (next-hop tracking in the IGP or any 433 other detection mechanism). Ingress replication MUST use the 434 forwarding information given by the remote Regular-IR Inclusive 435 Multicast Routes as described in [RFC7432]. 437 d) In a service where there is one or more AR-REPLICATORs (based on 438 the received Replicator-AR routes for the EVI), the AR-LEAF can 439 locally select which AR-REPLICATOR it sends the BM traffic to: 441 o A single AR-REPLICATOR MAY be selected for all the BM packets 442 received on the AR-LEAF attachment circuits (ACs) for a given 443 EVI. This selection is a local decision and it does not have 444 to match other AR-LEAF's selection within the same EVI. 446 o An AR-LEAF MAY select more than one AR-REPLICATOR and do 447 either per-flow or per-EVI load balancing. 449 o In case of a failure on the selected AR-REPLICATOR, another 450 AR-REPLICATOR will be selected. 452 o When an AR-REPLICATOR is selected, the AR-LEAF MUST send all 453 the BM packets to that AR-REPLICATOR using the forwarding 454 information given by the Replicator-AR route for the chosen 455 AR-REPLICATOR, with tunnel type = 0x0A (AR tunnel). The 456 underlay destination IP address MUST be the AR-IP advertised 457 by the AR-REPLICATOR in the Replicator-AR route. 459 o AR-LEAF nodes SHALL send service-level BM control plane 460 packets following regular IR procedures. An example would be 461 IGMP, MLD or PIM multicast packets. The AR-REPLICATORs MUST 462 not replicate these control plane packets to other overlay 463 tunnels since they will use the regular IR-IP Address. 465 e) The use of an AR-REPLICATOR-activation-timer (in seconds) on the 466 AR-LEAF nodes is RECOMMENDED. Upon receiving a new Replicator-AR 467 route where the AR-REPLICATOR is selected, the AR-LEAF will run a 468 timer before programming the new AR-REPLICATOR. This will give the 469 AR-REPLICATOR some time to program the AR-LEAF nodes before the 470 AR-LEAF sends BM traffic. 472 4.3. RNVE procedures 474 RNVE (Regular Network Virtualization Edge node) is defined as an 475 NVE/PE without AR-REPLICATOR or AR-LEAF capabilities that does IR as 476 described in [RFC7432]. The RNVE does not signal any AR role and is 477 unaware of the AR-REPLICATOR/LEAF roles in the EVI. The RNVE will 478 ignore the Flags in the Regular-IR routes and will ignore the 479 Replicator-AR routes (due to an unknown tunnel type in the PTA) and 480 the Leaf-AD routes (due to the IP-address-specific route-target). 482 This role provides EVPN with the backwards compatibility required in 483 optimized-IR EVIs. Figure 1 shows NVE2 as RNVE. 485 4.4. Forwarding behavior in non-selective AR EVIs 487 In AR EVIs, BM (Broadcast and Multicast) traffic between two NVEs may 488 follow a different path than unicast traffic. This solution proposes 489 the replication of BM through the AR-REPLICATOR node, whereas 490 unknown/known unicast will be delivered directly from the source node 491 to the destination node without being replicated by any intermediate 492 node. Unknown unicast SHALL follow the same path as known unicast 493 traffic in order to avoid packet reordering for unicast applications 494 and simplify the control and data plane procedures. Section 4.4.1. 495 describes the expected forwarding behavior for BM traffic in nodes 496 acting as AR-REPLICATOR, AR-LEAF and RNVE. Section 4.4.2. describes 497 the forwarding behavior for unknown unicast traffic. 499 Note that known unicast forwarding is not impacted by this solution. 501 4.4.1. Broadcast and Multicast forwarding behavior 503 The expected behavior per role is described in this section. 505 4.4.1.1. Non-selective AR-REPLICATOR BM forwarding 507 The AR-REPLICATORs will build a flooding list composed of ACs and 508 overlay tunnels to remote nodes in the EVI. Some of those overlay 509 tunnels MAY be flagged as non-BM receivers based on the BM flag 510 received from the remote nodes in the EVI. 512 o When an AR-REPLICATOR receives a BM packet on an AC, it will 513 forward the BM packet to its flooding list (including local ACs and 514 remote NVE/PEs), skipping the non-BM overlay tunnels. 516 o When an AR-REPLICATOR receives a BM packet on an overlay tunnel, it 517 will check the destination IP of the underlay IP header and: 519 - If the destination IP matches its AR-IP, the AR-REPLICATOR will 520 forward the BM packet to its flooding list (ACs and overlay 521 tunnels) excluding the non-BM overlay tunnels. The AR-REPLICATOR 522 will do source squelching to ensure the traffic is not sent back 523 to the originating AR-LEAF. If the encapsulation is MPLSoGRE (or 524 MPLSoUDP) and the EVI label is not the bottom of the stack, the 525 AR-REPLICATOR MUST copy the rest of the labels and forward them 526 to the egress overlay tunnels. 528 - If the destination IP matches its IR-IP, the AR-REPLICATOR will 529 skip all the overlay tunnels from the flooding list, i.e. it 530 will only replicate to local ACs. This is the regular IR 531 behavior described in [RFC7432]. 533 4.4.1.2. Non-selective AR-LEAF BM forwarding 535 The AR-LEAF nodes will build two flood-lists: 537 1) Flood-list #1 - composed of ACs and an AR-REPLICATOR-set of 538 overlay tunnels. The AR-REPLICATOR-set is defined as one or more 539 overlay tunnels to the AR-IP Addresses of the remote AR- 540 REPLICATOR(s) in the EVI. The selection of more than one AR- 541 REPLICATOR is described in section 4.2. and it is a local AR- 542 LEAF decision. 544 2) Flood-list #2 - composed of ACs and overlay tunnels to the 545 remote IR-IP Addresses. 547 When an AR-LEAF receives a BM packet on an AC, it will check the 548 AR-REPLICATOR-set: 550 o If the AR-REPLICATOR-set is empty, the AR-LEAF will send the packet 551 to flood-list #2. 553 o If the AR-REPLICATOR-set is NOT empty, the AR-LEAF will send the 554 packet to flood-list #1, where only one of the overlay tunnels of 555 the AR-REPLICATOR-set is used. 557 When an AR-LEAF receives a BM packet on an overlay tunnel, will 558 forward the BM packet to its local ACs and never to an overlay 559 tunnel. This is the regular IR behavior described in [RFC7432]. 561 4.4.1.3. RNVE BM forwarding 563 The RNVE is completely unaware of the AR-REPLICATORs, AR-LEAF nodes 564 and BM/U flags (that information is ignored). Its forwarding behavior 565 is the regular IR behavior described in [RFC7432]. Any regular non-AR 566 node is fully compatible with the RNVE role described in this 567 document. 569 4.4.2. Unknown unicast forwarding behavior 571 The expected behavior is described in this section. 573 4.4.2.1. Non-selective AR-REPLICATOR/LEAF Unknown unicast forwarding 575 While the forwarding behavior in AR-REPLICATORs and AR-LEAF nodes is 576 different for BM traffic, as far as Unknown unicast traffic 577 forwarding is concerned, AR-LEAF nodes behave exactly in the same way 578 as AR-REPLICATORs do. 580 The AR-REPLICATOR/LEAF nodes will build a flood-list composed of ACs 581 and overlay tunnels to the IR-IP Addresses of the remote nodes in the 582 EVI. Some of those overlay tunnels MAY be flagged as non-U (Unknown 583 unicast) receivers based on the U flag received from the remote nodes 584 in the EVI. 586 o When an AR-REPLICATOR/LEAF receives an unknown packet on an AC, it 587 will forward the unknown packet to its flood-list, skipping the 588 non-U overlay tunnels. 590 o When an AR-REPLICATOR/LEAF receives an unknown packet on an overlay 591 tunnel will forward the unknown packet to its local ACs and never 592 to an overlay tunnel. This is the regular IR behavior described in 593 [RFC7432]. 595 4.4.2.2. RNVE Unknown unicast forwarding 597 As described for BM traffic, the RNVE is completely unaware of the 598 REPLICATORs, LEAF nodes and BM/U flags (that information is ignored). 599 Its forwarding behavior is the regular IR behavior described in 600 [RFC7432], also for Unknown unicast traffic. Any regular non-AR node 601 is fully compatible with the RNVE role described in this document. 603 5. Selective Assisted-Replication (AR) Solution Description 605 Figure 1 is also used to describe the selective AR solution, however 606 in this section we consider NVE2 as one more AR-LEAF for EVI-1. The 607 solution is called "selective" because a given AR-REPLICATOR MUST 608 replicate the BM traffic to only the AR-LEAF that requested the 609 replication (as opposed to all the AR-LEAF nodes) and MAY replicate 610 the BM traffic to the RNVEs. The same AR roles defined in section 4 611 are used here, however the procedures are slightly different. 613 The following sub-sections describe the differences in the procedures 614 of AR-REPLICATOR/LEAFs compared to the non-selective AR solution. 615 There is no change on the RNVEs. 617 5.1. Selective AR-REPLICATOR procedures 619 In our example in figure 1, PE1 and PE2 are defined as Selective AR- 620 REPLICATORs. The following considerations apply to the Selective AR- 621 REPLICATOR role: 623 a) The Selective AR-REPLICATOR capability SHOULD be an administrative 624 choice in any NVE/PE that is part of an AR-enabled EVI, as the AR 625 role itself. This administrative option MAY be implemented as a 626 system level option as opposed to as a per-MAC-VRF option. 628 b) Each AR-REPLICATOR will build a list of AR-REPLICATOR, AR-LEAF and 629 RNVE nodes (AR-LEAF nodes that sent only a regular-IR route are 630 accounted as RNVEs by the AR-REPLICATOR). In spite of the 631 'Selective' administrative option, an AR-REPLICATOR MUST NOT 632 behave as a Selective AR-REPLICATOR if at least one of the AR- 633 REPLICATORs has the L flag NOT set. If at least one AR-REPLICATOR 634 sends a Replicator-AR route with L=0 (in the EVI context), the 635 rest of the AR-REPLICATORs will fall back to non-selective AR 636 mode. 638 b) The Selective AR-REPLICATOR MUST follow the procedures described 639 in section 4.1, except for the following differences: 641 o The Replicator-AR route MUST include L=1 (Leaf Information 642 Required) in the Replicator-AR route. This flag is used by the 643 AR-REPLICATORs to advertise their 'selective' AR-REPLICATOR 644 capabilities. In addition, the AR-REPLICATOR auto-configures 645 its IP-address-specific import route-target as described in 646 section 3. 648 o The AR-REPLICATOR will build a 'selective' AR-LEAF-set with 649 the list of nodes that requested replication to its own AR-IP. 650 For instance, assuming NVE1 and NVE2 advertise a Leaf-AD route 651 with PE1's IP-address-specific route-target and NVE3 652 advertises a Leaf-AD route with PE2's IP-address-specific 653 route-target, PE1 MUST only add NVE1/NVE2 to its selective AR- 654 LEAF-set for EVI-1, and exclude NVE3. 656 o When a node defined and operating as Selective AR-REPLICATOR 657 receives a packet on an overlay tunnel, it will do a tunnel 658 destination IP lookup and if the destination IP is the AR- 659 REPLICATOR AR-IP Address, the node MUST replicate the packet 660 to: 662 + local ACs 663 + overlay tunnels in the Selective AR-LEAF-set (excluding the 664 overlay tunnel to the source AR-LEAF). 665 + overlay tunnels to the RNVEs if the tunnel source IP is the 666 IR-IP of an AR-LEAF (in any other case, the AR-REPLICATOR 667 MUST NOT replicate the BM traffic to remote RNVEs). In other 668 words, the first-hop selective AR-REPLICATOR will replicate 669 to all the RNVEs. 670 + overlay tunnels to the remote Selective AR-REPLICATORs if 671 the tunnel source IP is an IR-IP of its own AR-LEAF-set (in 672 any other case, the AR-REPLICATOR MUST NOT replicate the BM 673 traffic to remote AR-REPLICATORs), where the tunnel 674 destination IP is the AR-IP of the remote Selective AR- 675 REPLICATOR. The tunnel destination IP AR-IP will be an 676 indication for the remote Selective AR-REPLICATOR that the 677 packet needs further replication to its AR-LEAFs. 679 5.2. Selective AR-LEAF procedures 681 A Selective AR-LEAF chooses a single Selective AR-REPLICATOR per EVI 682 and: 684 o Sends all the EVI BM traffic to that AR-REPLICATOR and 685 o Expects to receive the BM traffic for a given EVI from the same AR- 686 REPLICATOR. 688 In the example of Figure 1, we consider NVE1/NVE2/NVE3 as Selective 689 AR-LEAFs. NVE1 selects PE1 as its Selective AR-REPLICATOR. If that is 690 so, NVE1 will send all its BM traffic for EVI-1 to PE1. If other AR- 691 LEAF/REPLICATORs send BM traffic, NVE1 will receive that traffic from 692 PE1. These are the differences in the behavior of a Selective AR-LEAF 693 compared to a non-selective AR-LEAF: 695 a) The AR-LEAF role selective capability SHOULD be an administrative 696 choice in any NVE/PE that is part of an AR-enabled EVI. This 697 administrative option to enable AR-LEAF capabilities MAY be 698 implemented as a system level option as opposed to as per-MAC-VRF 699 option. 701 b) The AR-LEAF MAY advertise a Regular-IR route if there are RNVEs in 702 the EVI. The Selective AR-LEAF MUST advertise a Leaf-AD route 703 after receiving a Replicator-AR route with L=1. It is recommended 704 that the Selective AR-LEAF waits for a timer t before sending the 705 Leaf-AD route, so that the AR-LEAF receives all the Replicator-AR 706 routes for the EVI. 708 c) In a service where there is more than one Selective AR-REPLICATORs 709 the Selective AR-LEAF MUST locally select a single Selective AR- 710 REPLICATOR for the EVI. Once selected: 712 o The Selective AR-LEAF will send a Leaf-AD route including the 713 Route-key and IP-address-specific route-target of the selected 714 AR-REPLICATOR. 716 o The Selective AR-LEAF will send all the BM packets received on 717 the attachment circuits (ACs) for a given EVI to that AR- 718 REPLICATOR. 720 o In case of a failure on the selected AR-REPLICATOR, another 721 AR-REPLICATOR will be selected and a new Leaf-AD update will 722 be issued for the new AR-REPLICATOR. This new route will 723 update the selective list in the new Selective AR-REPLICATOR. 724 In case of failure on the active Selective AR-REPLICATOR, it 725 is recommended for the Selective AR-LEAF to revert to IR 726 behavior for a timer t to speed up the convergence. When the 727 timer expires, the Selective AR-LEAF will resume its AR mode 728 with the new Selective AR-REPLICATOR. 730 All the AR-LEAFs in an EVI are expected to be configured as either 731 selective or non-selective. A mix of selective and non-selective AR- 732 LEAFs SHOULD NOT coexist in the same EVI. In case there is a non- 733 selective AR-LEAF, its BM traffic sent to a selective AR-REPLICATOR 734 will not be replicated to other AR-LEAFs that are not in its 735 Selective AR-LEAF-set. 737 5.3. Forwarding behavior in selective AR EVIs 739 This section describes the differences of the selective AR forwarding 740 mode compared to the non-selective mode. Compared to section 4.4, 741 there are no changes for the forwarding behavior in RNVEs or for 742 unknown unicast traffic. 744 5.3.1. Selective AR-REPLICATOR BM forwarding 746 The Selective AR-REPLICATORs will build two flood-lists: 748 1) Flood-list #1 - composed of ACs and overlay tunnels to the 749 remote nodes in the EVI, always using the IR-IPs in the tunnel 750 destination IP addresses. Some of those overlay tunnels MAY be 751 flagged as non-BM receivers based on the BM flag received from 752 the remote nodes in the EVI. 754 2) Flood-list #2 - composed of ACs, a Selective AR-LEAF-set and a 755 Selective AR-REPLICATOR-set, where: 757 o The Selective AR-LEAF-set is composed of the overlay tunnels 758 to the AR-LEAFs that advertise a Leaf-AD route for the local 759 AR-REPLICATOR. This set is updated with every Leaf-AD route 760 received/withdrawn from a new AR-LEAF. 762 o The Selective AR-REPLICATOR-set is composed of the overlay 763 tunnels to all the AR-REPLICATORs that send a Replicator-AR 764 route with L=1. The AR-IP addresses are used as tunnel 765 destination IP. 767 When a Selective AR-REPLICATOR receives a BM packet on an AC, it will 768 forward the BM packet to its flood-list #1, skipping the non-BM 769 overlay tunnels. 771 When a Selective AR-REPLICATOR receives a BM packet on an overlay 772 tunnel, it will check the destination and source IPs of the underlay 773 IP header and: 775 - If the destination IP matches its AR-IP and the source IP 776 matches an IP of its own Selective AR-LEAF-set, the AR- 777 REPLICATOR will forward the BM packet to its flood-list #2, as 778 long as the list of AR-REPLICATORs for the EVI matches the 779 Selective AR-REPLICATOR-set. If the Selective AR-REPLICATOR-set 780 does not match the list of AR-REPLICATORs, the node reverts back 781 to non-selective mode and flood-list #1 is used. 783 - If the destination IP matches its AR-IP and the source IP does 784 not match any IP of its Selective AR-LEAF-set, the AR-REPLICATOR 785 will forward the BM packet to flood-list #2 but skipping the AR- 786 REPLICATOR-set. 788 - If the destination IP matches its IR-IP, the AR-REPLICATOR will 789 use flood-list #1 but MUST skip all the overlay tunnels from the 790 flooding list, i.e. it will only replicate to local ACs. This is 791 the regular-IR behavior described in [RFC7432]. 793 In any case, non-BM overlay tunnels are excluded from flood-lists 794 and, also, source squelching is always done in order to ensure the 795 traffic is not sent back to the originating source. If the 796 encapsulation is MPLSoGRE (or MPLSoUDP) and the EVI label is not the 797 bottom of the stack, the AR-REPLICATOR MUST copy the rest of the 798 labels when forwarding them to the egress overlay tunnels. 800 5.3.2. Selective AR-LEAF BM forwarding 801 The Selective AR-LEAF nodes will build two flood-lists: 803 1) Flood-list #1 - composed of ACs and the overlay tunnel to the 804 selected AR-REPLICATOR (using the AR-IP as the tunnel 805 destination IP). 807 2) Flood-list #2 - composed of ACs and overlay tunnels to the 808 remote IR-IP Addresses. 810 When an AR-LEAF receives a BM packet on an AC, it will check if there 811 is any selected AR-REPLICATOR. If there is, flood-list #1 will be 812 used. Otherwise, flood-list #2 will. 814 When an AR-LEAF receives a BM packet on an overlay tunnel, will 815 forward the BM packet to its local ACs and never to an overlay 816 tunnel. This is the regular IR behavior described in [RFC7432]. 818 6. Pruned-Flood-Lists (PFL) 820 In addition to AR, the second optimization supported by this solution 821 is the ability for the all the EVI nodes to signal Pruned-Flood-Lists 822 (PFL). As described in section 3, an EVPN node can signal a given 823 value for the BM and U PFL flags in the IR Inclusive Multicast 824 Routes, where: 826 + BM= Broadcast and Multicast (BM) flag. BM=1 means "prune-me" from 827 the BM flood-list. BM=0 means regular behavior. 829 + U= Unknown flag. U=1 means "prune-me" from the Unknown flood-list. 830 U=0 means regular behavior. 832 The ability to signal these PFL flags is an administrative choice. 833 Upon receiving a non-zero PFL flag, a node MAY decide to honor the 834 PFL flag and remove the sender from the corresponding flood-list. A 835 given EVI node receiving BUM traffic on an overlay tunnel MUST 836 replicate the traffic normally, regardless of the signaled PFL 837 flags. 839 This optimization MAY be used along with the AR solution. 841 6.1. A PFL example 843 In order to illustrate the use of the solution described in this 844 document, we will assume that EVI-1 in figure 1 is optimized-IR 845 enabled and: 847 o PE1 and PE2 are administratively configured as AR-REPLICATORs, due 848 to their high-performance replication capabilities. PE1 and PE2 849 will send a Replicator-AR route with BM/U flags = 00. 851 o NVE1 and NVE3 are administratively configured as AR-LEAF nodes, due 852 to their low-performance software-based replication capabilities. 853 They will advertise a Regular-IR route with type AR-LEAF. Assuming 854 both NVEs advertise all the attached VMs in EVPN as soon as they 855 come up and don't have any VMs interested in multicast 856 applications, they will be configured to signal BM/U flags = 11 for 857 EVI-1. 859 o NVE2 is optimized-IR unaware; therefore it takes on the RNVE role 860 in EVI-1. 862 Based on the above assumptions the following forwarding behavior will 863 take place: 865 (1) Any BM packets sent from VM11 will be sent to VM12 and PE1. PE1 866 will forward further the BM packets to TS1, WAN link, PE2 and 867 NVE2, but not to NVE3. PE2 and NVE2 will replicate the BM packets 868 to their local ACs but we will avoid NVE3 having to replicate 869 unnecessarily those BM packets to VM31 and VM32. 871 (2) Any BM packets received on PE2 from the WAN will be sent to PE1 872 and NVE2, but not to NVE1 and NVE3, sparing the two hypervisors 873 from replicating unnecessarily to their local VMs. PE1 and NVE2 874 will replicate to their local ACs only. 876 (3) Any Unknown unicast packet sent from VM31 will be forwarded by 877 NVE3 to NVE2, PE1 and PE2 but not NVE1. The solution avoids the 878 unnecessary replication to NVE1, since the destination of the 879 unknown traffic cannot be at NVE1. 881 (4) Any Unknown unicast packet sent from TS1 will be forwarded by PE1 882 to the WAN link, PE2 and NVE2 but not to NVE1 and NVE3, since the 883 target of the unknown traffic cannot be at those NVEs. 885 7. AR Procedures for single-IP AR-REPLICATORS 887 The procedures explained in sections 4 (Non-selective AR) and 5 888 (Selective AR) assume that the AR-REPLICATOR can use two local 889 routable IP addresses to terminate and originate NVO tunnels, i.e. 890 IR-IP and AR-IP addresses. This is usually the case for PE-based AR- 891 REPLICATOR nodes. 893 In some cases, the AR-REPLICATOR node does not support more than one 894 IP address to terminate and originate NVO tunnels, i.e. the IR-IP and 895 AR-IP are the same IP addresses. This may be the case in some 896 software-based or low-end AR-REPLICATOR nodes. If this is the case, 897 the procedures in sections 4 and 5 must be modified in the following 898 way: 900 o The Replicator-AR routes generated by the AR-REPLICATOR use an AR- 901 IP that will match its IR-IP. In order to differentiate the data 902 plane packets that need to use IR from the packets that must use AR 903 forwarding mode, the Replicator-AR route must advertise a different 904 VNI/VSID than the one used by the Regular-IR route. For instance, 905 the AR-REPLICATOR will advertise AR-VNI along with the Replicator- 906 AR route and IR-VNI along with the Regular-IR route. Since both 907 routes have the same key, different RDs are needed for both routes. 909 o An AR-REPLICATOR will perform IR or AR forwarding mode for the 910 incoming Overlay packets based on an ingress VNI lookup, as opposed 911 to the tunnel IP DA lookup described in sections 4 and 5. Note 912 that, when replicating to remote AR-REPLICATOR nodes, the use of 913 the IR-VNI or AR-VNI advertised by the egress node will determine 914 the IR or AR forwarding mode at the subsequent AR-REPLICATOR. 916 The rest of the procedures will follow what is described in sections 917 4 and 5. 919 8. AR Procedures and EVPN Multi-homing Split-Horizon 921 If VXLAN or NVGRE are used, and if the Split-horizon is based on the 922 tunnel IP SA and "Local-Bias" as described in [EVPN-OVERLAY], the 923 Split-horizon check will not work if there is an Ethernet-Segment 924 shared between two AR-LEAF nodes, and the AR-REPLICATOR changes the 925 tunnel IP SA of the packets with its own AR-IP. 927 In order to be compatible with the IP SA split-horizon check, the AR- 928 REPLICATOR MAY keep the original received tunnel IP SA when 929 replicating packets to a remote AR-LEAF or AR-REPLICATOR. This will 930 allow DF (Designated Forwarder) AR-LEAF nodes to apply Split-horizon 931 check procedures for BM packets, before sending them to the local 932 Ethernet-Segment. 934 When EVPN is used for MPLS over GRE (or UDP), the ESI-label based 935 split-horizon procedure as in [RFC7432] will not work for multi-homed 936 Ethernet-Segments defined on AR-LEAF nodes. "Local-Bias" is 937 recommended in this case, as in the case of VXLAN or NVGRE explained 938 above. The "Local-Bias" and tunnel IP SA preservation mechanisms 939 provide the required split-horizon behavior in non-selective or 940 selective AR. 942 Note that if the AR-REPLICATOR implementation keeps the received 943 tunnel IP SA, the use of uRPF in the IP fabric based on the tunnel IP 944 SA MUST be disabled. 946 9. Out-of-band distribution of Broadcast/Multicast traffic 948 The use of out-of-band mechanisms to distribute BM traffic between 949 AR-REPLICATORS MAY be used. 951 10. Benefits of the optimized-IR solution 953 A solution for the optimization of Ingress Replication in EVPN is 954 described in this document (optimized-IR). The solution brings the 955 following benefits: 957 o Optimizes the multicast forwarding in low-performance NVEs, by 958 relaying the replication to high-performance NVEs (AR-REPLICATORs) 959 and while preserving the packet ordering for unicast applications. 961 o Reduces the flooded traffic in NVO networks where some NVEs do not 962 need broadcast/multicast and/or unknown unicast traffic. 964 o It is fully compatible with existing EVPN implementations and EVPN 965 functions for NVO overlay tunnels. Optimized-IR NVEs and regular 966 NVEs can be even part of the same EVI. 968 o It does not require any PIM-based tree in the NVO core of the 969 network. 971 11. Conventions used in this document 973 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 974 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 975 document are to be interpreted as described in RFC-2119 [RFC2119]. 977 In this document, these words will appear with that interpretation 978 only when in ALL CAPS. Lower case uses of these words are not to be 979 interpreted as carrying RFC-2119 significance. 981 In this document, the characters ">>" preceding an indented line(s) 982 indicates a compliance requirement statement using the key words 983 listed above. This convention aids reviewers in quickly identifying 984 or finding the explicit compliance requirements of this RFC. 986 12. Security Considerations 987 This section will be added in future versions. 989 13. IANA Considerations 991 IANA has allocated the following Border Gateway Protocol (BGP) 992 Parameters: 994 1) Allocation in the P-Multicast Service Interface Tunnel (PMSI 995 Tunnel) Tunnel Types registry: 997 Value Meaning Reference 998 0x0A Assisted-Replication Tunnel [This document] 1000 2) Allocations in the P-Multicast Service Interface (PMSI) Tunnel 1001 Attribute Flags registry: 1003 Value Name Reference 1004 3-4 Assisted-Replication Type (T) [This document] 1005 5 Broadcast and Multicast (BM) [This document] 1006 6 Unknown (U) [This document] 1008 14. Terminology 1010 Regular-IR: Refers to Regular Ingress Replication, where the source 1011 NVE/PE sends a copy to each remote NVE/PE part of the EVI. 1013 AR-IP: IP address owned by the AR-REPLICATOR and used to 1014 differentiate the ingress traffic that must follow the AR 1015 procedures. 1017 IR-IP: IP address used for Ingress Replication as in [RFC7432]. 1019 AR-VNI: VNI advertised by the AR-REPLICATOR along with the 1020 Replicator-AR route. It is used to identify the ingress 1021 packets that must follow AR procedures ONLY in the Single-IP 1022 AR-REPLICATOR case. 1024 IR-VNI: VNI advertised along with the RT-3 for IR. 1026 AR forwarding mode: for an AR-LEAF, it means sending an AC BM packet 1027 to a single AR-REPLICATOR with tunnel destination IP AR-IP. 1028 For an AR-REPLICATOR, it means sending a BM packet to a 1029 selective number or all the overlay tunnels when the packet 1030 was previously received from an overlay tunnel. 1032 IR forwarding mode: it refers to the Ingress Replication behavior 1033 explained in [RFC7432]. It means sending an AC BM packet copy 1034 to each remote PE/NVE in the EVI and sending an overlay BM 1035 packet only to the ACs and not other overlay tunnels. 1037 PTA: PMSI Tunnel Attribute 1039 RT-3: EVPN Route Type 3, Inclusive Multicast Ethernet Tag route 1041 RT-11: EVPN Route Type 11, Leaf Auto-Discovery (AD) route 1043 15. References 1045 15.1 Normative References 1047 [RFC6514]Aggarwal, R., Rosen, E., Morin, T., and Y. Rekhter, "BGP 1048 Encodings and Procedures for Multicast in MPLS/BGP IP VPNs", 1049 RFC 6514, DOI 10.17487/RFC6514, February 2012, . 1052 [RFC7432]Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A., 1053 Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based Ethernet 1054 VPN", RFC 7432, DOI 10.17487/RFC7432, February 2015, . 1057 [RFC7902]Rosen, E. and Morin, T., "Registry and Extensions for P- 1058 Multicast Service Interface Tunnel Attribute Flags", June 2016, 1059 . 1061 [EVPN-BUM] Zhang et al., "Updates on EVPN BUM Procedures", draft- 1062 ietf-bess-evpn-bum-procedure-updates-01.txt, work in progress, 1063 December 2016. 1065 15.2 Informative References 1067 [EVPN-OVERLAY] Sajassi-Drake et al., "A Network Virtualization 1068 Overlay Solution using EVPN", draft-ietf-bess-evpn-overlay-07.txt, 1069 work in progress, December 2016. 1071 16. Acknowledgments 1073 The authors would like to thank Neil Hart, David Motz, Kiran Nagaraj, 1074 Dai Truong, Thomas Morin, Jeffrey Zhang and Shankar Murthy for their 1075 valuable feedback and contributions. 1077 17. Authors' Addresses 1078 Jorge Rabadan (Editor) 1079 Nokia 1080 777 E. Middlefield Road 1081 Mountain View, CA 94043 USA 1082 Email: jorge.rabadan@nokia.com 1084 Senthil Sathappan 1085 Nokia 1086 Email: senthil.sathappan@nokia.com 1088 Mukul Katiyar 1089 Juniper Networks 1090 Email: mkatiyar@juniper.net 1092 Wim Henderickx 1093 Nokia 1094 Email: wim.henderickx@nokia.com 1096 Ravi Shekhar 1097 Juniper Networks 1098 Email: rshekhar@juniper.net 1100 Nischal Sheth 1101 Juniper Networks 1102 Email: nsheth@juniper.net 1104 Wen Lin 1105 Juniper Networks 1106 Email: wlin@juniper.net 1108 Ali Sajassi 1109 Cisco 1110 Email: sajassi@cisco.com 1112 Aldrin Isaac 1113 Juniper 1114 Email: aisaac@juniper.net 1116 Mudassir Tufail 1117 Citibank 1118 mudassir.tufail@citi.com