idnits 2.17.1 draft-rabadan-nvo3-evpn-applicability-01.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 doesn't use any RFC 2119 keywords, yet seems to have RFC 2119 boilerplate text. -- The document date (February 9, 2018) is 2265 days in the past. Is this intentional? Checking references for intended status: Informational ---------------------------------------------------------------------------- == Missing Reference: 'EVPN-PREFIX' is mentioned on line 878, but not defined == Unused Reference: 'RFC7365' is defined on line 972, but no explicit reference was found in the text == Unused Reference: 'EVPN-USAGE' is defined on line 1000, but no explicit reference was found in the text == Unused Reference: 'BUM-UPDATE' is defined on line 1058, but no explicit reference was found in the text == Outdated reference: A later version (-11) exists of draft-ietf-bess-evpn-prefix-advertisement-08 == Outdated reference: A later version (-15) exists of draft-ietf-bess-evpn-inter-subnet-forwarding-03 == Outdated reference: A later version (-09) exists of draft-ietf-bess-evpn-usage-06 == Outdated reference: A later version (-12) exists of draft-ietf-bess-evpn-overlay-08 == Outdated reference: A later version (-16) exists of draft-ietf-nvo3-geneve-05 == Outdated reference: A later version (-12) exists of draft-ietf-nvo3-encap-01 == Outdated reference: A later version (-22) exists of draft-ietf-idr-tunnel-encaps-03 == Outdated reference: A later version (-08) exists of draft-jain-bess-evpn-lsp-ping-05 == Outdated reference: A later version (-04) exists of draft-snr-bess-evpn-loop-protect-00 == Outdated reference: A later version (-16) exists of draft-ietf-bess-evpn-proxy-arp-nd-03 == Outdated reference: A later version (-21) exists of draft-ietf-bess-evpn-igmp-mld-proxy-00 == Outdated reference: A later version (-02) exists of draft-skr-bess-evpn-pim-proxy-01 == Outdated reference: A later version (-12) exists of draft-ietf-bess-evpn-optimized-ir-02 == Outdated reference: A later version (-13) exists of draft-ietf-bess-evpn-pref-df-00 == Outdated reference: A later version (-03) exists of draft-ietf-bess-evpn-ac-df-02 == Outdated reference: A later version (-10) exists of draft-ietf-bess-dci-evpn-overlay-05 == Outdated reference: A later version (-14) exists of draft-ietf-bess-evpn-bum-procedure-updates-02 == Outdated reference: A later version (-02) exists of draft-rabadan-sajassi-bess-evpn-ipvpn-interworking-00 == Outdated reference: A later version (-04) exists of draft-boutros-bess-evpn-geneve-01 == Outdated reference: A later version (-04) exists of draft-sajassi-bess-evpn-mvpn-seamless-interop-00 Summary: 0 errors (**), 0 flaws (~~), 26 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 NVO3 Workgroup J. Rabadan, Ed. 3 Internet Draft M. Bocci 4 Intended status: Informational Nokia 6 S. Boutros 7 WMware 9 A. Sajassi 10 Cisco 12 Expires: August 13, 2018 February 9, 2018 14 Applicability of EVPN to NVO3 Networks 15 draft-rabadan-nvo3-evpn-applicability-01 17 Abstract 19 In NVO3 networks, Network Virtualization Edge (NVE) devices sit at 20 the edge of the underlay network and provide Layer-2 and Layer-3 21 connectivity among Tenant Systems (TSes) of the same tenant. The NVEs 22 need to build and maintain mapping tables so that they can deliver 23 encapsulated packets to their intended destination NVE(s). While 24 there are different options to create and disseminate the mapping 25 table entries, NVEs may exchange that information directly among 26 themselves via a control-plane protocol, such as EVPN. EVPN provides 27 an efficient, flexible and unified control-plane option that can be 28 used for Layer-2 and Layer-3 Virtual Network (VN) service 29 connectivity. This document describes the applicability of EVPN to 30 NVO3 networks and how EVPN solves the challenges in those networks. 32 Status of this Memo 34 This Internet-Draft is submitted in full conformance with the 35 provisions of BCP 78 and BCP 79. 37 Internet-Drafts are working documents of the Internet Engineering 38 Task Force (IETF), its areas, and its working groups. Note that 39 other groups may also distribute working documents as Internet- 40 Drafts. 42 Internet-Drafts are draft documents valid for a maximum of six months 43 and may be updated, replaced, or obsoleted by other documents at any 44 time. It is inappropriate to use Internet-Drafts as reference 45 material or to cite them other than as "work in progress." 46 The list of current Internet-Drafts can be accessed at 47 http://www.ietf.org/ietf/1id-abstracts.txt 49 The list of Internet-Draft Shadow Directories can be accessed at 50 http://www.ietf.org/shadow.html 52 This Internet-Draft will expire on August 13, 2018. 54 Copyright Notice 56 Copyright (c) 2018 IETF Trust and the persons identified as the 57 document authors. All rights reserved. 59 This document is subject to BCP 78 and the IETF Trust's Legal 60 Provisions Relating to IETF Documents 61 (http://trustee.ietf.org/license-info) in effect on the date of 62 publication of this document. Please review these documents 63 carefully, as they describe your rights and restrictions with respect 64 to this document. Code Components extracted from this document must 65 include Simplified BSD License text as described in Section 4.e of 66 the Trust Legal Provisions and are provided without warranty as 67 described in the Simplified BSD License. 69 Table of Contents 71 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 72 2. EVPN and NVO3 Terminology . . . . . . . . . . . . . . . . . . . 3 73 3. Why Is EVPN Needed In NVO3 Networks? . . . . . . . . . . . . . 6 74 4. Applicability of EVPN to NVO3 Networks . . . . . . . . . . . . 8 75 4.1. EVPN Route Types used in NVO3 Networks . . . . . . . . . . 8 76 4.2. EVPN Basic Applicability For Layer-2 Services . . . . . . . 9 77 4.2.1. Auto-Discovery and Auto-Provisioning of ES, 78 Multi-Homing PEs and NVE services . . . . . . . . . . . 10 79 4.2.2. Remote NVE Auto-Discovery . . . . . . . . . . . . . . . 11 80 4.2.3. Distribution Of Tenant MAC and IP Information . . . . . 12 81 4.3. EVPN Basic Applicability for Layer-3 Services . . . . . . . 13 82 4.4. EVPN as a Control Plane for NVO3 Encapsulations and 83 GENEVE . . . . . . . . . . . . . . . . . . . . . . . . . . 15 84 4.5. EVPN OAM and application to NVO3 . . . . . . . . . . . . . 15 85 4.6. EVPN as the control plane for NVO3 security . . . . . . . . 16 86 4.7. Advanced EVPN Features For NVO3 Networks . . . . . . . . . 16 87 4.7.1. Virtual Machine (VM) Mobility . . . . . . . . . . . . . 16 88 4.7.2. MAC Protection, Duplication Detection and Loop 89 Protection . . . . . . . . . . . . . . . . . . . . . . 16 90 4.7.3. Reduction/Optimization of BUM Traffic In Layer-2 91 Services . . . . . . . . . . . . . . . . . . . . . . . 17 93 4.7.4. Ingress Replication (IR) Optimization For BUM Traffic . 18 94 4.7.5. EVPN Multi-homing . . . . . . . . . . . . . . . . . . . 18 95 4.7.6. EVPN Recursive Resolution for Inter-Subnet Unicast 96 Forwarding . . . . . . . . . . . . . . . . . . . . . . 19 97 4.7.7. EVPN Optimized Inter-Subnet Multicast Forwarding . . . 21 98 4.7.8. Data Center Interconnect (DCI) . . . . . . . . . . . . 21 99 5. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 22 100 6. Conventions used in this document . . . . . . . . . . . . . . . 22 101 7. Security Considerations . . . . . . . . . . . . . . . . . . . . 22 102 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 22 103 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 22 104 9.1 Normative References . . . . . . . . . . . . . . . . . . . . 23 105 9.2 Informative References . . . . . . . . . . . . . . . . . . . 23 106 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 25 107 11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 25 108 12. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 25 110 1. Introduction 112 In NVO3 networks, Network Virtualization Edge (NVE) devices sit at 113 the edge of the underlay network and provide Layer-2 and Layer-3 114 connectivity among Tenant Systems (TSes) of the same tenant. The NVEs 115 need to build and maintain mapping tables so that they can deliver 116 encapsulated packets to their intended destination NVE(s). While 117 there are different options to create and disseminate the mapping 118 table entries, NVEs may exchange that information directly among 119 themselves via a control-plane protocol, such as EVPN. EVPN provides 120 an efficient, flexible and unified control-plane option that can be 121 used for Layer-2 and Layer-3 Virtual Network (VN) service 122 connectivity. 124 In this document, we assume that the EVPN control-plane module 125 resides in the NVEs. The NVEs can be virtual switches in hypervisors, 126 TOR/Leaf switches or Data Center Gateways. Note that Network 127 Virtualization Authorities (NVAs) may be used to provide the 128 forwarding information to the NVEs, and in that case, EVPN could be 129 used to disseminate the information across multiple federated NVAs. 130 The applicability of EVPN would then be similar to the one described 131 in this document. However, for simplicity, the description assumes 132 control-plane communication among NVE(s). 134 2. EVPN and NVO3 Terminology 136 o EVPN: Ethernet Virtual Private Networks, as described in [RFC7432]. 138 o PE: Provider Edge router. 140 o NVO3 or Overlay tunnels: Network Virtualization Over Layer-3 141 tunnels. In this document, NVO3 tunnels or simply Overlay tunnels 142 will be used interchangeably. Both terms refer to a way to 143 encapsulate tenant frames or packets into IP packets whose IP 144 Source Addresses (SA) or Destination Addresses (DA) belong to the 145 underlay IP address space, and identify NVEs connected to the same 146 underlay network. Examples of NVO3 tunnel encapsulations are VXLAN 147 [RFC7348], [GENEVE] or MPLSoUDP [RFC7510]. 149 o VXLAN: Virtual eXtensible Local Area Network, an NVO3 encapsulation 150 defined in [RFC7348]. 152 o GENEVE: Generic Network Virtualization Encapsulation, an NVO3 153 encapsulation defined in [GENEVE]. 155 o CLOS: a multistage network topology described in [CLOS1953], where 156 all the edge switches (or Leafs) are connected to all the core 157 switches (or Spines). Typically used in Data Centers nowadays. 159 o ECMP: Equal Cost Multi-Path. 161 o NVE: Network Virtualization Edge is a network entity that sits at 162 the edge of an underlay network and implements L2 and/or L3 network 163 virtualization functions. The network-facing side of the NVE uses 164 the underlying L3 network to tunnel tenant frames to and from other 165 NVEs. The tenant-facing side of the NVE sends and receives Ethernet 166 frames to and from individual Tenant Systems. In this document, an 167 NVE could be implemented as a virtual switch within a hypervisor, a 168 switch or a router, and runs EVPN in the control-plane. 170 o EVI: or EVPN Instance. It is a Layer-2 Virtual Network that uses an 171 EVPN control-plane to exchange reachability information among the 172 member NVEs. It corresponds to a set of MAC-VRFs of the same 173 tenant. See MAC-VRF in this section. 175 o BD: or Broadcast Domain, it corresponds to a tenant IP subnet. If 176 no suppression techniques are used, a BUM frame that is injected in 177 a BD will reach all the NVEs that are attached to that BD. An EVI 178 may contain one or multiple BDs depending on the service model 179 [RFC7432]. This document will use the term BD to refer to a tenant 180 subnet. 182 o EVPN VLAN-based service model: it refers to one of the three 183 service models defined in [RFC7432]. It is characterized as a BD 184 that uses a single VLAN per physical access port to attach tenant 185 traffic to the BD. In this service model, there is only one BD per 186 EVI. 188 o EVPN VLAN-bundle service model: similar to VLAN-based but uses a 189 bundle of VLANs per physical port to attach tenant traffic to the 190 BD. As in VLAN-based, in this model there is a single BD per EVI. 192 o EVPN VLAN-aware bundle service model: similar to the VLAN-bundle 193 model but each individual VLAN value is mapped to a different BD. 194 In this model there are multiple BDs per EVI for a given tenant. 195 Each BD is identified by an "Ethernet Tag", that is a control-plane 196 value that identifies the routes for the BD within the EVI. 198 o IP-VRF: an IP Virtual Routing and Forwarding table, as defined in 199 [RFC4364]. It stores IP Prefixes that are part of the tenant's IP 200 space, and are distributed among NVEs of the same tenant by EVPN. 201 Route-Distinghisher (RD) and Route-Target(s) (RTs) are required 202 properties of an IP-VRF. An IP-VRF is instantiated in an NVE for a 203 given tenant, if the NVE is attached to multiple subnets of the 204 tenant and local inter-subnet-forwarding is required across those 205 subnets. 207 o MAC-VRF: a MAC Virtual Routing and Forwarding table, as defined in 208 [RFC7432]. The instantiation of an EVI (EVPN Instance) in an NVE. 209 Route-distinghisher (RD) and Route-Target(s) (RTs) are required 210 properties of a MAC-VRF and they are normally different than the 211 ones defined in the associated IP-VRF (if the MAC-VRF has an IRB 212 interface). 214 o BT: a Bridge Table, as defined in [RFC7432]. A BT is the 215 instantiation of a BD in an NVE. When there is a single BD on a 216 given EVI, the MAC-VRF is equivalent to the BT on that NVE. 218 o AC: Attachment Circuit or logical interface associated to a given 219 BT. To determine the AC on which a packet arrived, the NVE will 220 examine the physical/logical port and/or VLAN tags (where the VLAN 221 tags can be individual c-tags, s-tags or ranges of both). 223 o IRB: Integrated Routing and Bridging interface. It refers to the 224 logical interface that connects a BD instance (or a BT) to an IP- 225 VRF and allows to forward packets with destination in a different 226 subnet. 228 o ES: Ethernet Segment. When a Tenant System (TS) is connected to one 229 or more NVEs via a set of Ethernet links, then that set of links is 230 referred to as an 'Ethernet segment'. Each ES is represented by a 231 unique Ethernet Segment Identifier (ESI) in the NVO3 network and 232 the ESI is used in EVPN routes that are specific to that ES. 234 o DF and NDF: they refer to Designated Forwarder and Non-Designated 235 Forwarder, which are the roles that a given PE can have in a given 236 ES. 238 o VNI: Virtual Network Identifier. Irrespective of the NVO3 239 encapsulation, the tunnel header always includes a VNI that is 240 added at the ingress NVE (based on the mapping table lookup) and 241 identifies the BT at the egress NVE. This VNI is called VNI in 242 VXLAN or GENEVE, VSID in nvGRE or Label in MPLSoGRE or MPLSoUDP. 243 This document will refer to VNI as a generic Virtual Network 244 Identifier for any NVO3 encapsulation. 246 o BUM: Broadcast, Unknown unicast and Multicast frames. 248 o SA and DA: they refer to Source Address and Destination Address. 249 They are used along with MAC or IP, e.g. IP SA or MAC DA. 251 o RT and RD: they refer to Route Target and Route Distinguisher. 253 o PTA: Provider Multicast Service Interface Tunnel Attribute. 255 o RT-1, RT-2, RT-3, etc.: they refer to Route Type followed by the 256 type number as defined in the IANA registry for EVPN route types. 258 o TS: Tenant System. 260 o ARP and ND: they refer to Address Resolution Protocol and Neighbor 261 Discovery protocol. 263 3. Why Is EVPN Needed In NVO3 Networks? 265 Data Centers have adopted NVO3 architectures mostly due to the issues 266 discussed in [RFC7364]. The architecture of a Data Center is nowadays 267 based on a CLOS design, where every Leaf is connected to a layer of 268 Spines, and there is a number of ECMP paths between any two leaf 269 nodes. All the links between Leaf and Spine nodes are routed links, 270 forming what we also know as an underlay IP Fabric. The underlay IP 271 Fabric does not have issues with loops or flooding (like old Spanning 272 Tree Data Center designs did), convergence is fast and ECMP provides 273 a fairly optimal bandwidth utilization on all the links. 275 On this architecture and as discussed by [RFC7364] multi-tenant 276 intra-subnet and inter-subnet connectivity services are provided by 277 NVO3 tunnels, being VXLAN [RFC7348] or [GENEVE] two examples of such 278 tunnels. 280 Why is a control-plane protocol along with NVO3 tunnels required? 281 There are three main reasons: 283 a) Auto-discovery of the remote NVEs that are attached to the same 284 VPN instance (Layer-2 and/or Layer-3) as the ingress NVE is. 286 b) Dissemination of the MAC/IP host information so that mapping 287 tables can be populated on the remote NVEs. 289 c) Advanced features such as MAC Mobility, MAC Protection, BUM and 290 ARP/ND traffic reduction/suppression, Multi-homing, Prefix 291 Independent Convergence (PIC) like functionality, Fast 292 Convergence, etc. 294 A possible approach to achieve points (a) and (b) above for 295 multipoint Ethernet services, is "Flood and Learn". "Flood and Learn" 296 refers to not using a specific control-plane on the NVEs, but rather 297 "Flood" BUM traffic from the ingress NVE to all the egress NVEs 298 attached to the same BD. The egress NVEs may then use data path MAC 299 SA "Learning" on the frames received over the NVO3 tunnels. When the 300 destination host replies back and the frames arrive at the NVE that 301 initially flooded BUM frames, the NVE will also "Learn" the MAC SA of 302 the frame encapsulated on the NVO3 tunnel. This approach has the 303 following drawbacks: 305 o In order to Flood a given BUM frame, the ingress NVE must know the 306 IP addresses of the remote NVEs attached to the same BD. This may 307 be done as follows: 309 - The remote tunnel IP addresses can be statically provisioned on 310 the ingress NVE. If the ingress NVE receives a BUM frame for the 311 BD on an ingress AC, it will do ingress replication and will send 312 the frame to all the configured egress NVE IP DAs in the BD. 314 - All the NVEs attached to the same BD can subscribe to an underlay 315 IP Multicast Group that is dedicated to that BD. When an ingress 316 NVE receives a BUM frame on an ingress AC, it will send a single 317 copy of the frame encapsulated into an NVO3 tunnel, using the 318 multicast address as IP DA of the tunnel. This solution requires 319 PIM in the underlay network and the association of individual BDs 320 to underlay IP multicast groups. 322 o "Flood and Learn" solves the issues of auto-discovery and learning 323 of the MAC to VNI/tunnel IP mapping on the NVEs for a given BD. 324 However, it does not provide a solution for advanced features and 325 it does not scale well. 327 EVPN provides a unified control-plane that solves the NVE auto- 328 discovery, tenant MAP/IP dissemination and advanced features in a 329 scalable way and keeping the independence of the underlay IP Fabric, 330 i.e. there is no need to enable PIM in the underlay network and 331 maintain multicast states for tenant BDs. 333 Section 4 describes how to apply EVPN to meet the control-plane 334 requirements in an NVO3 network. 336 4. Applicability of EVPN to NVO3 Networks 338 This section discusses the applicability of EVPN to NVO3 networks. 339 The intend is not to provide a comprehensive explanation of the 340 protocol itself but give an introduction and point at the 341 corresponding reference document, so that the reader can easily find 342 more details if needed. 344 4.1. EVPN Route Types used in NVO3 Networks 346 EVPN supports multiple Route Types and each type has a different 347 function. For convenience, Table 1 shows a summary of all the 348 existing EVPN route types and its usage. We will refer to these route 349 types as RT-x throughout the rest of the document, where x is the 350 type number included in the first column of Table 1. 352 +----+------------------------+-------------------------------------+ 353 |Type|Description |Usage | 354 +----+------------------------+-------------------------------------+ 355 |1 |Ethernet Auto-Discovery |Multi-homing: | 356 | | | Per-ES: Mass withdrawal | 357 | | | Per-EVI: aliasing/backup | 358 +----+------------------------+-------------------------------------+ 359 |2 |MAC/IP Advertisement |Host MAC/IP dissemination | 360 | | |Supports MAC mobility and protection | 361 +----+------------------------+-------------------------------------+ 362 |3 |Inclusive Multicast |NVE discovery and BUM flooding tree | 363 | |Ethernet Tag |setup | 364 +----+------------------------+-------------------------------------+ 365 |4 |Ethernet Segment |Multi-homing: ES auto-discovery and | 366 | | |DF Election | 367 +----+------------------------+-------------------------------------+ 368 |5 |IP Prefix |IP Prefix dissemination | 369 +----+------------------------+-------------------------------------+ 370 |6 |Selective Multicast |Indicate interest for a multicast | 371 | |Ethernet Tag |S,G or *,G | 372 +----+------------------------+-------------------------------------+ 373 |7 |IGMP Join Synch |Multi-homing: S,G or *,G state synch | 374 +----+------------------------+-------------------------------------+ 375 |8 |IGMP Leave Synch |Multi-homing: S,G or *,G leave synch | 376 +----+------------------------+-------------------------------------+ 377 |9 |Per-Region I-PMSI A-D |BUM tree creation across regions | 378 +----+------------------------+-------------------------------------+ 379 |10 |S-PMSI A-D |Multicast tree for S,G or *,G states | 380 +----+------------------------+-------------------------------------+ 381 |11 |Leaf A-D |Used for responses to explicit | 382 | | |tracking | 383 +----+------------------------+-------------------------------------+ 385 Table 1 EVPN route types 387 4.2. EVPN Basic Applicability For Layer-2 Services 389 Although the applicability of EVPN to NVO3 networks spans multiple 390 documents, EVPN's baseline specification is [RFC7432]. [RFC7432] 391 allows multipoint layer-2 VPNs to be operated as [RFC4364] IP-VPNs, 392 where MACs and the information to setup flooding trees are 393 distributed by MP-BGP. Based on [RFC7432], [EVPN-OVERLAY] describes 394 how to use EVPN to deliver Layer-2 services specifically in NVO3 395 Networks. 397 Figure 1 represents a Layer-2 service deployed with an EVPN BD in an 398 NVO3 network. 400 +--TS2---+ 401 * | Single-Active 402 * | ESI-1 403 +----+ +----+ 404 |BD1 | |BD1 | 405 +-------------| |--| |-----------+ 406 | +----+ +----+ | 407 | NVE2 NVE3 NVE4 408 | EVPN NVO3 Network +----+ 409 NVE1(IP-A) | BD1|=====+ 410 +-------------+ RT-2 | | | 411 | +-MAC-VRF1+ | +-------+ +----+ | 412 | | +----+ | | |MAC1 | NVE5 TS3 413 TS1--------|BD1 | | | |IP1 | +----+ | 414 MAC1 | | +----+ | | |Label L|---> | BD1|=====+ 415 IP1 | +---------+ | |NH IP-A| | | All-Active 416 | Hypervisor | +-------+ +----+ ESI-2 417 +-------------+ | 418 +--------------------------------------+ 420 Figure 1 EVPN for L2 in an NVO3 Network - example 422 In a simple NVO3 network, such as the example of Figure 1, these are 423 the basic constructs that EVPN uses for Layer-2 services (or Layer-2 424 Virtual Networks): 426 o BD1 is an EVPN Broadcast Domain for a given tenant and TS1, TS2 and 427 TS3 are connected to it. The five represented NVEs are attached to 428 BD1 and are connected to the same underlay IP network. That is, 429 each NVE learns the remote NVEs' loopback addresses via underlay 430 routing protocol. 432 o NVE1 is deployed as a virtual switch in a Hypervisor with IP-A as 433 underlay loopback IP address. The rest of the NVEs in Figure 1 are 434 physical switches and TS2/TS3 are multi-homed to them. TS1 is a 435 virtual machine, identified by MAC1 and IP1. 437 4.2.1. Auto-Discovery and Auto-Provisioning of ES, Multi-Homing PEs and 438 NVE services 440 Auto-discovery is one of the basic capabilities of EVPN. The 441 provisioning of EVPN components in NVEs is significantly automated, 442 simplifying the deployment of services and minimizing manual 443 operations that are prone to human error. 445 These are some of the Auto-Discovery and Auto-Provisioning 446 capabilities available in EVPN: 448 o Automation on Ethernet Segments (ES): an ES is defined as a group 449 of NVEs that are attached to the same TS or network. An ES is 450 identified by an Ethernet Segment Identifier (ESI) in the control 451 plane, but neither the ESI nor the NVEs that share the same ES are 452 required to be manually provisioned in the local NVE: 454 - If the multi-homed TS or network are running protocols such as 455 LACP (Link Aggregation Control Protocol), MSTP (Multiple-instance 456 Spanning Tree Protocol), G.8032, etc. and all the NVEs in the ES 457 can listen to the protocol PDUs to uniquely identify the multi- 458 homed TS/network, then the ESI can be "auto-sensed" or "auto- 459 provisioned" following the guidelines in [RFC7432] section 5. 461 - As described in [RFC7432], EVPN can also auto-derive the BGP 462 parameters required to advertise the presence of a local ES in 463 the control plane (RT and RD). Local ESes are advertised using 464 RT-4s and the ESI-import Route-Target used by RT-4s can be auto- 465 derived based on the procedures of [RFC7432], section 7.6. 467 - By listening to other RT-4s that match the local ESI and import 468 RT, an NVE can also auto-discover the other NVEs participating in 469 the multi-homing for the ES. 471 - Once the NVE has auto-discovered all the NVEs attached to the 472 same ES, the NVE can automatically perform the DF Election 473 algorithm (which determines the NVE that will forward traffic to 474 the multi-homed TS/network). EVPN guarantees that all the NVEs in 475 the ES have a consistent DF Election. 477 o Auto-provisioning of services: when deploying a Layer-2 Service for 478 a tenant in an NVO3 network, all the NVEs attached to the same 479 subnet must be configured with a MAC-VRF and the BD for the subnet, 480 as well as certain parameters for them. Note that, if the EVPN 481 service model is VLAN-based or VLAN-bundle, implementations do not 482 normally have a specific provisioning for the BD (since it is in 483 that case the same construct as the MAC-VRF). EVPN allows auto- 484 deriving as many MAC-VRF parameters as possible. As an example, the 485 MAC-VRF's RT and RD for the EVPN routes may be auto-derived. 486 Section 5.1.2.1 in [EVPN-OVERLAY] specifies how to auto-derive a 487 MAC-VRF's RT as long as VLAN-based service model is implemented. 488 [RFC7432] specifies how to auto-derive the RD. 490 4.2.2. Remote NVE Auto-Discovery 492 Auto-discovery via MP-BGP is used to discover the remote NVEs 493 attached to a given BD, NVEs participating in a given redundancy 494 group, the tunnel encapsulation types supported by an NVE, etc. 496 In particular, when a new MAC-VRF and BD are enabled, the NVE will 497 advertise a new RT-3. Besides other fields, the RT-3 will encode the 498 IP address of the advertising NVE, the Ethernet Tag (which is zero in 499 case of VLAN-based and VLAN-bundle models) and also a PMSI Tunnel 500 Attribute (PTA) that indicates the information about the intended way 501 to deliver BUM traffic for the BD. 503 In the example of Figure 1, when MAC-VRF1/BD1 are enabled, NVE1 will 504 send an RT-3 including its own IP address, Ethernet-Tag for BD1 and 505 the PTA. Assuming Ingress Replication (IR), the RT-3 will include an 506 identification for IR in the PTA and the VNI the NVEs must use to 507 send BUM traffic to the advertising NVE. The other NVEs in the BD, 508 will import the RT-3 and will add NVE1's IP address to the flooding 509 list for BD1. Note that the RT-3 is also sent with a BGP 510 encapsulation attribute [TUNNEL-ENCAP] that indicates what NVO3 511 encapsulation the remote NVEs should use when sending BUM traffic to 512 NVE1. 514 Refer to [RFC7432] for more information about the RT-3 and forwarding 515 of BUM traffic, and to [EVPN-OVERLAY] for its considerations on NVO3 516 networks. 518 4.2.3. Distribution Of Tenant MAC and IP Information 520 Tenant MAC/IP information is advertised to remote NVEs using RT-2s. 521 Following the example of Figure 1: 523 o In a given EVPN BD, TSes' MAC addresses are first learned at the 524 NVE they are attached to, via data path or management plane 525 learning. In Figure 1 we assume NVE1 learns MAC1/IP1 in the 526 management plane (for instance, via Cloud Management System) since 527 the NVE is a virtual switch. NVE2, NVE3, NVE4 and NVE4 are TOR/Leaf 528 switches and they normally learn MAC addresses via data path. 530 o Once NVE1's BD1 learns MAC1/IP1, NVE1 advertises that information 531 along with a VNI and Next Hop IP-A in an RT-2. The EVPN routes are 532 advertised using the RD/RTs of the MAC-VRF where the BD belongs. 533 All the NVEs in BD1 learn local MAC/IP addresses and advertise them 534 in RT-2 routes in a similar way. 536 o The remote NVEs can then add MAC1 to their mapping table for BD1 537 (BT). For instance, when TS3 sends frames to NVE4 with MAC DA = 538 MAC1, NVE4 does a MAC lookup on the BT that yields IP-A and Label 539 L. NVE4 can then encapsulate the frame into an NVO3 tunnel with IP- 540 A as the tunnel IP DA and L as the Virtual Network Identifier. Note 541 that the RT-2 may also contain the host's IP address (as in the 542 example of Figure 1). While the MAC of the received RT-2 is 543 installed in the BT, the IP address may be installed in the Proxy- 544 ARP/ND table (if enabled) or in the ARP/IP-VRF tables if the BD has 545 an IRB. See section 4.7.3. to see more information about Proxy- 546 ARP/ND and section 4.3. for more details about IRB and Layer-3 547 services. 549 Refer to [RFC7432] and [EVPN-OVERLAY] for more information about the 550 RT-2 and forwarding of known unicast traffic. 552 4.3. EVPN Basic Applicability for Layer-3 Services 554 [IP-PREFIX] and [INTER-SUBNET] are the reference documents that 555 describe how EVPN can be used for Layer-3 services. Inter Subnet 556 Forwarding in EVPN networks is implemented via IRB interfaces between 557 BDs and IP-VRFs. As discussed, an EVPN BD corresponds to an IP 558 subnet. When IP packets generated in a BD are destined to a different 559 subnet (different BD) of the same tenant, the packets are sent to the 560 IRB attached to local BD in the source NVE. As discussed in [INTER- 561 SUBNET], depending on how the IP packets are forwarded between the 562 ingress NVE and the egress NVE, there are two forwarding models: 563 Asymmetric and Symmetric. 565 The Asymmetric model is illustrated in the example of Figure 2 and it 566 requires the configuration of all the BDs of the tenant in all the 567 NVEs attached to the same tenant. In that way, there is no need to 568 advertise IP Prefixes between NVEs since all the NVEs are attached to 569 all the subnets. It is called Asymmetric because the ingress and 570 egress NVEs do not perform the same number of lookups in the data 571 plane. In Figure 2, if TS1 and TS2 are in different subnets, and TS1 572 sends IP packets to TS2, the following lookups are required in the 573 data path: a MAC lookup (on BD1's table), an IP lookup (on the IP- 574 VRF) and a MAC lookup (on BD2's table) at the ingress NVE1 and then 575 only a MAC lookup at the egress NVE. The two IP-VRFs in Figure 2 are 576 not connected by tunnels and all the connectivity between the NVEs is 577 done based on tunnels between the BDs. 579 +-------------------------------------+ 580 | EVPN NVO3 | 581 | | 582 NVE1 NVE2 583 +--------------------+ +--------------------+ 584 | +---+IRB +------+ | | +------+IRB +---+ | 585 TS1-----|BD1|----|IP-VRF| | | |IP-VRF|----|BD1| | 586 | +---+ | | | | | | +---+ | 587 | +---+ | | | | | | +---+ | 588 | |BD2|----| | | | | |----|BD2|----TS2 589 | +---+IRB +------+ | | +------+IRB +---+ | 590 +--------------------+ +--------------------+ 591 | | 592 +-------------------------------------+ 594 Figure 2 EVPN for L3 in an NVO3 Network - Asymmetric model 596 In the Symmetric model, depicted in Figure 3, there are the same data 597 path lookups at the ingress and egress NVEs. For example, if TS1 598 sends IP packets to TS3, the following data path lookups are 599 required: a MAC lookup at NVE1's BD1 table, an IP lookup at NVE1's 600 IP-VRF and then IP lookup and MAC lookup at NVE2's IP-VRF and BD3 601 respectively. In the Symmetric model, the Inter Subnet connectivity 602 between NVEs is done based on tunnels between the IP-VRFs. 604 +-------------------------------------+ 605 | EVPN NVO3 | 606 | | 607 NVE1 NVE2 608 +--------------------+ +--------------------+ 609 | +---+IRB +------+ | | +------+IRB +---+ | 610 TS1-----|BD1|----|IP-VRF| | | |IP-VRF|----|BD3|-----TS3 611 | +---+ | | | | | | +---+ | 612 | +---+IRB | | | | +------+ | 613 TS2-----|BD2|----| | | +--------------------+ 614 | +---+ +------+ | | 615 +--------------------+ | 616 | | 617 +-------------------------------------+ 619 Figure 3 EVPN for L3 in an NVO3 Network - Symmetric model 621 The Symmetric model scales better than the Asymmetric model because 622 it does not require the NVEs to be attached to all the tenant's 623 subnets. However, it requires the use of NVO3 tunnels on the IP-VRFs 624 and the exchange of IP Prefixes between the NVEs in the control 625 plane. EVPN uses RT-2 and RT-5 routes for the exchange of host IP 626 routes (in the case of RT-2 and RT-5) and IP Prefixes (RT-5s) of any 627 length. As an example, in Figure 3, NVE2 needs to advertise TS3's 628 host route and/or TS3's subnet, so that the IP lookup on NVE1's IP- 629 VRF succeeds. 631 [INTER-SUBNET] specifies the use of RT-2s for the advertisement of 632 host routes. Section 4.4.1 in [IP-PREFIX] specifies the use of RT-5s 633 for the advertisement of IP Prefixes in an "Interface-less IP-VRF-to- 634 IP-VRF Model". 636 4.4. EVPN as a Control Plane for NVO3 Encapsulations and GENEVE 638 [EVPN-OVERLAY] describes how to use EVPN for NVO3 encapsulations, 639 such us VXLAN, nvGRE or MPLSoGRE. The procedures can be easily 640 applicable to any other NVO3 encapsulation, in particular GENEVE. 642 The NVO3 working group has been working on different data plane 643 encapsulations. The Generic Network Virtualization Encapsulation 644 [GENEVE] has been recommended to be the proposed standard for NVO3 645 Encapsulation. The EVPN control plane can signal the GENEVE 646 encapsulation type in the BGP Tunnel Encapsulation Extended Community 647 (see [TUNNEL-ENCAP]). 649 The NVO3 encapsulation design team has made a recommendation in 650 [NVO3-ENCAP] for a control plane to: 652 1- Negotiate a subset of GENEVE option TLVs that can be carried on a 653 GENEVE tunnel 655 2- Enforce an order for GENEVE option TLVs and 657 3- Limit the total number of options that could be carried on a 658 GENEVE tunnel. 660 The EVPN control plane can easily extend the BGP Tunnel Encapsulation 661 Attribute sub-TLV [TUNNEL-ENCAP] to specify the GENEVE tunnel options 662 that can be received or transmitted over a GENEVE tunnels by a given 663 NVE. [EVPN-GENEVE] describes the EVPN control plane extensions to 664 support GENEVE. 666 4.5. EVPN OAM and application to NVO3 668 EVPN OAM (as in [EVPN-LSP-PING]) defines mechanisms to detect data 669 plane failures in an EVPN deployment over an MPLS network. These 670 mechanisms detect failures related to P2P and P2MP connectivity, for 671 multi-tenant unicast and multicast L2 traffic, between multi-tenant 672 access nodes connected to EVPN PE(s), and in a single-homed, single- 673 active or all-active redundancy model. 675 In general, EVPN OAM mechanisms defined for EVPN deployed in MPLS 676 networks are equally applicable for EVPN in NVO3 networks. 678 4.6. EVPN as the control plane for NVO3 security 680 EVPN can be used to signal the security protection capabilities of a 681 sender NVE, as well as what portion of an NVO3 packet (taking a 682 GENEVE packet as an example) can be protected by the sender NVE, to 683 ensure the privacy and integrity of tenant traffic carried over the 684 NVO3 tunnels. 686 4.7. Advanced EVPN Features For NVO3 Networks 688 This section describes how EVPN can be used to deliver advanced 689 capabilities in NVO3 networks. 691 4.7.1. Virtual Machine (VM) Mobility 693 [RFC7432] replaces the traditional Ethernet Flood-and-Learn behavior 694 among NVEs with BGP-based MAC learning, which in return provides more 695 control over the location of MAC addresses in the BD and consequently 696 advanced features, such as MAC Mobility. If we assume that VM 697 Mobility means the VM's MAC and IP addresses move with the VM, EVPN's 698 MAC Mobility is the required procedure that facilitates VM Mobility. 699 According to [RFC7432] section 15, when a MAC is advertised for the 700 first time in a BD, all the NVEs attached to the BD will store 701 Sequence Number zero for that MAC. When the MAC "moves" within the 702 same BD but to a remote NVE, the NVE that just learned locally the 703 MAC, increases the Sequence Number in the RT-2's MAC Mobility 704 extended community to indicate that it owns the MAC now. That makes 705 all the NVE in the BD change their tables immediately with no need to 706 wait for any aging timer. EVPN guarantees a fast MAC Mobility without 707 flooding or black-holes in the BD. 709 4.7.2. MAC Protection, Duplication Detection and Loop Protection 711 The advertisement of MACs in the control plane, allows advanced 712 features such as MAC protection, Duplication Detection and Loop 713 Protection. 715 [RFC7432] MAC Protection refers to EVPN's ability to indicate - in an 716 RT-2 - that a MAC must be protected by the NVE receiving the route. 717 The Protection is indicated in the "Sticky bit" of the MAC Mobility 718 extended community sent along the RT-2 for a MAC. NVEs' ACs that are 719 connected to subject-to-be-protected servers or VMs may set the 720 Sticky bit on the RT-2s sent for the MACs associated to the ACs. Also 721 statically configured MAC addresses should be advertised as Protected 722 MAC addresses, since they are not subject to MAC Mobility procedures. 724 [RFC7432] MAC Duplication Detection refers to EVPN's ability to 725 detect duplicate MAC addresses. A "MAC move" is a relearn event that 726 happens at an access AC or through an RT-2 with a Sequence Number 727 that is higher than the stored one for the MAC. When a MAC moves a 728 number of times N within an M-second window between two NVEs, the MAC 729 is declared as Duplicate and the detecting NVE does not re-advertise 730 the MAC anymore. 732 While [RFC7432] provides MAC Duplication Detection, it does not 733 protect the BD against loops created by backdoor links between NVEs. 734 However, the same principle (based on the Sequence Number) may be 735 extended to protect the BD against loops. When a MAC is detected as 736 duplicate, the NVE may install it as a black-hole MAC and drop 737 received frames with MAC SA and MAC DA matching that duplicate MAC. 738 Loop Protection is described in [LOOP]. 740 4.7.3. Reduction/Optimization of BUM Traffic In Layer-2 Services 742 In BDs with a significant amount of flooding due to Unknown unicast 743 and Broadcast frames, EVPN may help reduce and sometimes even 744 suppress the flooding. 746 In BDs where most of the Broadcast traffic is caused by ARP (Address 747 Resolution Protocol) and ND (Neighbor Discovery) protocols on the 748 TSes, EVPN's Proxy-ARP and Proxy-ND capabilities may reduce the 749 flooding drastically. The use of Proxy-ARP/ND is specified in [PROXY- 750 ARP-ND]. 752 Proxy-ARP/ND procedures along with the assumption that TSes always 753 issue a GARP (Gratuitous ARP) or an unsolicited Neighbor 754 Advertisement message when they come up in the BD, may drastically 755 reduce the unknown unicast flooding in the BD. 757 The flooding caused by TSes' IGMP/MLD or PIM messages in the BD may 758 also be suppressed by the use of IGMP/MLD and PIM Proxy functions, as 759 specified in [IGMP-MLD-PROXY] and [PIM-PROXY]. These two documents 760 also specify how to forward IP multicast traffic efficiently within 761 the same BD, translate soft state IGMP/MLD/PIM messages into hard 762 state BGP routes and provide fast-convergence redundancy for IP 763 Multicast on multi-homed Ethernet Segments (ESes). 765 4.7.4. Ingress Replication (IR) Optimization For BUM Traffic 767 When an NVE attached to a given BD needs to send BUM traffic for the 768 BD to the remote NVEs attached to the same BD, IR is a very common 769 option in NVO3 networks, since it is completely independent of the 770 multicast capabilities of the underlay network. Also, if the 771 optimization procedures to reduce/suppress the flooding in the BD are 772 enabled (section 4.7.3), in spite of creating multiple copies of the 773 same frame at the ingress NVE, IR may be good enough. However, in BDs 774 where Multicast (or Broadcast) traffic is significant, IR may be very 775 inefficient and cause performance issues on virtual-switch-based 776 NVEs. 778 [OPT-IR] specifies the use of AR (Assisted Replication) NVO3 tunnels 779 in EVPN BDs. AR retains the independence of the underlay network 780 while providing a way to forward Broadcast and Multicast traffic 781 efficiently. AR uses AR-REPLICATORs that can replicate the 782 Broadcast/Multicast traffic on behalf of the AR-LEAF NVEs. The AR- 783 LEAF NVEs are typically virtual-switches or NVEs with limited 784 replication capabilities. AR can work in a single-stage replication 785 mode (Non-Selective Mode) or in a dual-stage replication mode 786 (Selective Mode). Both modes are detailed in [OPT-IR]. 788 In addition, [OPT-IR] also describes a procedure to avoid sending 789 Broadcast, Multicast or Unknown unicast to certain NVEs that don't 790 need that type of traffic. This is done by enabling PFL (Pruned Flood 791 Lists) on a given BD. For instance, an virtual-switch NVE that learns 792 all its local MAC addresses for a BD via Cloud Management System, 793 does not need to receive the BD's Unknown unicast traffic. PFLs help 794 optimize the BUM flooding in the BD. 796 4.7.5. EVPN Multi-homing 798 Another fundamental concept in EVPN is multi-homing. A given TS can 799 be multi-homed to two or more NVEs for a given BD, and the set of 800 links connected to the same TS is defined as Ethernet Segment (ES). 801 EVPN supports single-active and all-active multi-homing. In single- 802 active multi-homing only one link in the ES is active. In all-active 803 multi-homing all the links in the ES are active for unicast traffic. 804 Both modes support load-balancing: 806 o Single-active multi-homing means per-service load-balancing 807 to/from the TS, for example, in Figure 1, for BD1 only one of the 808 NVEs can forward traffic from/to TS2. For a different BD, the 809 other NVE may forward traffic. 811 o All-active multi-homing means per-flow load-balanding for unicast 812 frames to/from the TS. That is, in Figure 1 and for BD1, both 813 NVE4 and NVE5 can forward known unicast traffic to/from TS3. For 814 BUM traffic only one of the two NVEs can forward traffic to TS3, 815 and both can forward traffic from TS3. 817 There are two key aspects of EVPN multi-homing: 819 o DF (Designated Forwarder) election: the DF is the NVE that 820 forwards the traffic to the ES in single-active mode. In case of 821 all-active, the DF is the NVE that forwards the BUM traffic to 822 the ES. 824 o Split-horizon function: prevents the TS from receiving echoed BUM 825 frames that the TS itself sent to the ES. This is especially 826 relevant in all-active ESes, where the TS may forward BUM frames 827 to a non-DF NVE that can flood the BUM frames back to the DF NVE 828 and then the TS. As an example, in Figure 1, assuming NVE4 is the 829 DF for ES-2 in BD1, BUM frames sent from TS3 to NVE5 will be 830 received at NVE4 and, since NVE4 is the DF for DB1, it will 831 forward them back to TS3. Split-horizon allows NVE4 (and any 832 multi-homed NVE for that matter) to identify if an EVPN BUM frame 833 is coming from the same ES or different, and if the frame belongs 834 to the same ES2, NVE4 will not forward the BUM frame to TS3, in 835 spite of being the DF. 837 While [RFC7432] describes the default algorithm for the DF Election, 838 [HRW-DF], [PREF-DF] and [AC-DF] specify other algorithms and 839 procedures that optimize the DF Election. 841 The Split-horizon function is specified in [RFC7432] and it is 842 carried out by using a special ESI-label that it identifies in the 843 data path, all the BUM frames being originated from a given NVE and 844 ES. Since the ESI-label is an MPLS label, it cannot be used in all 845 the non-MPLS NVO3 encapsulations, therefore [EVPN-OVERLAY] defines a 846 modified Split-horizon procedure that is based on the IP SA of the 847 NVO3 tunnel, known as "Local-Bias". It is worth noting that Local- 848 Bias only works for all-active multi-homing, and not for single- 849 active multi-homing. 851 4.7.6. EVPN Recursive Resolution for Inter-Subnet Unicast Forwarding 852 Section 4.3. describes how EVPN can be used for Inter Subnet 853 Forwarding among subnets of the same tenant. RT-2s and RT-5s allow 854 the advertisement of host routes and IP Prefixes (RT-5) of any 855 length. The procedures outlined by section 4.3. are similar to the 856 ones in [RFC4364], only for NVO3 tunnels. However, [EVPN-PREFIX] also 857 defines advanced Inter Subnet Forwarding procedures that allow the 858 resolution of RT-5s to not only BGP next-hops but also "overlay 859 indexes" that can be a MAC, a GW IP or an ESI, all of them in the 860 tenant space. 862 Figure 4 illustrates an example that uses Recursive Resolution to a 863 GWIP as per [IP-PREFIX] section 4.4.2. In this example, IP-VRFs in 864 NVE1 and NVE2 are connected by a SBD (Supplementary BD). An SBD is a 865 BD that connects all the IP-VRFs of the same tenant, via IRB, and has 866 no ACs. NVE1 advertises the host route TS2-IP/L (IP address and 867 Prefix Length of TS2) in an RT-5 with overlay index GWIP=IP1. Also, 868 IP1 is advertised in an RT-2 associated to M1, VNI-S and BGP next-hop 869 NVE1. Upon importing the two routes, NVE2 installs TS2-IP/L in the 870 IP-VRF with a next-hop that is the GWIP IP1. NVE2 also installs M1 in 871 the SBD, with VNI-S and NVE1 as next-hop. If TS3 sends a packet with 872 IP DA=TS2, NVE2 will perform a Recursive Resolution of the RT-5 873 prefix information to the forwarding information of the correlated 874 RT-2. The RT-5's Recursive Resolution has several advantages such as 875 better convergence in scaled networks (since multiple RT-5s can be 876 invalidated with a single withdrawal of the overlay index route) or 877 the ability to advertise multiple RT-5s from an overlay index that 878 can move or change dynamically. [EVPN-PREFIX] describes a few use- 879 cases. 881 +-------------------------------------+ 882 | EVPN NVO3 | 883 | + 884 NVE1 NVE2 885 +--------------------+ +--------------------+ 886 | +---+IRB +------+ | | +------+IRB +---+ | 887 TS1-----|BD1|----|IP-VRF| | | |IP-VRF|----|BD3|-----TS3 888 | +---+ | |-(SBD)------(SBD)-| | +---+ | 889 | +---+IRB | |IRB(IP1/M1) IRB+------+ | 890 TS2-----|BD2|----| | | +-----------+--------+ 891 | +---+ +------+ | | 892 +--------------------+ | 893 | RT-2(M1,IP1,VNI-S,NVE1)--> | 894 | RT-5(TS2-IP/L,GWIP=IP1)--> | 895 +-------------------------------------+ 897 Figure 4 EVPN for L3 - Recursive Resolution example 899 4.7.7. EVPN Optimized Inter-Subnet Multicast Forwarding 901 The concept of the SBD described in section 4.7.6 is also used in 902 [OISM] for the procedures related to Inter Subnet Multicast 903 Forwarding across BDs of the same tenant. For instance, [OISM] allows 904 the efficient forwarding of IP multicast traffic from any BD to any 905 other BD (or even to the same BD where the Source resides). The 906 [OISM] procedures are supported along with EVPN multi-homing, and for 907 any tree allowed on NVO3 networks, including IR or AR. [OISM] also 908 describes the interoperability between EVPN and other multicast 909 technologies such as MVPN (Multicast VPN) and PIM for inter-subnet 910 multicast. 912 [EVPN-MVPN] describes another potential solution to support EVPN to 913 MVPN interoperability. 915 4.7.8. Data Center Interconnect (DCI) 917 Tenant Layer-2 and Layer-3 services deployed on NVO3 networks must be 918 extended to remote NVO3 networks that are connected via non-NOV3 WAN 919 networks (mostly MPLS based WAN networks). [EVPN-DCI] defines some 920 architectural models that can be used to interconnect NVO3 networks 921 via MPLS WAN networks. 923 When NVO3 networks are connected by MPLS WAN networks, [EVPN-DCI] 924 specifies how EVPN can be used end-to-end, in spite of using a 925 different encapsulation in the WAN. 927 Even if EVPN can also be used in the WAN for Layer-2 and Layer-3 928 services, there may be a need to provide a Gateway function between 929 EVPN for NVO3 encapsulations and IPVPN for MPLS tunnels. [EVPN-IPVPN] 930 specifics the interworking function between EVPN and IPVPN for 931 unicast Inter Subnet Forwarding. If Inter Subnet Multicast Forwarding 932 is also needed across an IPVPN WAN, [OISM] describes the required 933 interworking between EVPN and MVPN. 935 5. Conclusion 937 EVPN provides a unified control-plane that solves the NVE auto- 938 discovery, tenant MAP/IP dissemination and advanced features required 939 by NVO3 networks, in a scalable way and keeping the independence of 940 the underlay IP Fabric, i.e. there is no need to enable PIM in the 941 underlay network and maintain multicast states for tenant BDs. 943 This document justifies the use of EVPN for NVO3 networks, discusses 944 its applicability to basic Layer-2 and Layer-3 connectivity 945 requirements, as well as advanced features such as MAC-mobility, MAC 946 Protection and Loop Protection, multi-homing, DCI and much more. 948 6. Conventions used in this document 950 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 951 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 952 "OPTIONAL" in this document are to be interpreted as described in BCP 953 14 [RFC2119] [RFC8174] when, and only when, they appear in all 954 capitals, as shown here. 956 7. Security Considerations 958 This section will be added in future versions. 960 8. IANA Considerations 962 None. 964 9. References 965 9.1 Normative References 967 [RFC7432] Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A., 968 Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based Ethernet 969 VPN", RFC 7432, DOI 10.17487/RFC7432, February 2015, . 972 [RFC7365] Lasserre, M., Balus, F., Morin, T., Bitar, N., and Y. 973 Rekhter, "Framework for Data Center (DC) Network Virtualization", 974 RFC 7365, DOI 10.17487/RFC7365, October 2014, . 977 [RFC7364] Narten, T., Ed., Gray, E., Ed., Black, D., Fang, L., 978 Kreeger, L., and M. Napierala, "Problem Statement: Overlays for 979 Network Virtualization", RFC 7364, DOI 10.17487/RFC7364, October 980 2014, . 982 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 983 Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 984 1997, . 986 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in 987 RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 988 2017, . 990 9.2 Informative References 992 [IP-PREFIX] Rabadan et al., "IP Prefix Advertisement in EVPN", 993 draft-ietf-bess-evpn-prefix-advertisement-08, work in progress, 994 October, 2017. 996 [INTER-SUBNET] Sajassi et al., "IP Inter-Subnet Forwarding in EVPN", 997 draft-ietf-bess-evpn-inter-subnet-forwarding-03, work in progress, 998 February, 2017 1000 [EVPN-USAGE] Rabadan et al., "Usage and applicability of BGP MPLS 1001 based Ethernet VPN", work in progress, draft-ietf-bess-evpn-usage-06, 1002 August 2017 1004 [EVPN-OVERLAY] Sajassi-Drake et al., "A Network Virtualization 1005 Overlay Solution using EVPN", work in progress, draft-ietf-bess- 1006 evpn-overlay-08, March 2017 1008 [GENEVE] Gross et al., "Geneve: Generic Network Virtualization 1009 Encapsulation", draft-ietf-nvo3-geneve-05, work in progress, 1010 September 2017 1012 [NVO3-ENCAP] Boutros et al., "NVO3 Encapsulation Considerations", 1013 draft-ietf-nvo3-encap-01, work in progress, October 2017 1015 [TUNNEL-ENCAP] Rosen et al., "The BGP Tunnel Encapsulation 1016 Attribute", draft-ietf-idr-tunnel-encaps-03, work in progress, May 1017 31, 2016. 1019 [EVPN-LSP-PING] Jain et al., "LSP-Ping Mechanisms for EVPN and PBB- 1020 EVPN", draft-jain-bess-evpn-lsp-ping-05, work in progress, July 2017 1022 [LOOP] Rabadan et al., "Loop Protection in EVPN networks", draft- 1023 snr-bess-evpn-loop-protect-00, work in progress, July 2017 1025 [PROXY-ARP-ND] Rabadan et al., "Operational Aspects of Proxy-ARP/ND 1026 in EVPN Networks", draft-ietf-bess-evpn-proxy-arp-nd-03, work in 1027 progress, October 2017 1029 [IGMP-MLD-PROXY] Sajassi et al., "IGMP and MLD Proxy for EVPN", 1030 draft-ietf-bess-evpn-igmp-mld-proxy-00, work in progress, March 2017 1032 [PIM-PROXY] Rabadan et al., "PIM Proxy in EVPN Networks", draft-skr- 1033 bess-evpn-pim-proxy-01, work in progress, October 2017 1035 [OPT-IR] Rabadan et al., "Optimized Ingress Replication solution for 1036 EVPN", draft-ietf-bess-evpn-optimized-ir-02, work in progress, August 1037 2017 1039 [HRW-DF] Mohanty et al., "A new Designated Forwarder Election for 1040 the EVPN", draft-ietf-bess-evpn-df-election-03, work in progress, 1041 October 2017 1043 [PREF-DF] Rabadan et al., "Preference-based EVPN DF Election", 1044 draft-ietf-bess-evpn-pref-df-00, work in progress, June 2017 1046 [AC-DF] Rabadan et al., "AC-Influenced Designated Forwarder Election 1047 for EVPN", draft-ietf-bess-evpn-ac-df-02, work in progress, October 1048 2017 1050 [OISM] Lin at al., "EVPN Optimized Inter-Subnet Multicast (OISM) 1051 Forwarding", draft-lin-bess-evpn-irb-mcast-04, work in progress, 1052 October 2017 1054 [EVPN-DCI] Rabadan et al., "Interconnect Solution for EVPN Overlay 1055 networks", draft-ietf-bess-dci-evpn-overlay-05, work in progress, 1056 July 2017 1058 [BUM-UPDATE] Zhang et al., "Updates on EVPN BUM Procedures", draft- 1059 ietf-bess-evpn-bum-procedure-updates-02, work in progress, September 1060 2017 1062 [EVPN-IPVPN] Rabadan-Sajassi et al., "EVPN Interworking with IPVPN", 1063 draft-rabadan-sajassi-bess-evpn-ipvpn-interworking-00, work in 1064 progress, October 2017 1066 [RFC7348] Mahalingam, M., Dutt, D., Duda, K., Agarwal, P., Kreeger, 1067 L., Sridhar, T., Bursell, M., and C. Wright, "Virtual eXtensible 1068 Local Area Network (VXLAN): A Framework for Overlaying Virtualized 1069 Layer 2 Networks over Layer 3 Networks", RFC 7348, DOI 1070 10.17487/RFC7348, August 2014, . 1073 [RFC7510] Xu, X., Sheth, N., Yong, L., Callon, R., and D. Black, 1074 "Encapsulating MPLS in UDP", RFC 7510, DOI 10.17487/RFC7510, April 1075 2015, . 1077 [RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private 1078 Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February 2006, 1079 . 1081 [CLOS1953] Clos, C., "A Study of Non-Blocking Switching Networks", 1082 The Bell System Technical Journal, Vol. 32(2), DOI 10.1002/j.1538- 1083 7305.1953.tb01433.x, March 1953. 1085 [EVPN-GENEVE] Boutros et al., "EVPN control plane for Geneve", 1086 draft-boutros-bess-evpn-geneve-01, work in progress, February 2018. 1088 [EVPN-MVPN] Sajassi et al., "Seamless Multicast Interoperability 1089 between EVPN and MVPN PEs", draft-sajassi-bess-evpn-mvpn-seamless- 1090 interop-00, work in progress, July 2017. 1092 10. Acknowledgments 1094 11. Contributors 1096 12. Authors' Addresses 1098 Jorge Rabadan (Editor) 1099 Nokia 1100 777 E. Middlefield Road 1101 Mountain View, CA 94043 USA 1102 Email: jorge.rabadan@nokia.com 1104 Sami Boutros 1105 VMware 1106 Email: sboutros@vmware.com 1108 Matthew Bocci 1109 Nokia 1110 Email: matthew.bocci@nokia.com 1112 Ali Sajassi 1113 Cisco 1114 Email: sajassi@cisco.com