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Summary: 1 error (**), 0 flaws (~~), 11 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 BESS Workgroup J. Rabadan 3 Internet Draft S. Sathappan 4 Intended status: Standards Track W. Henderickx 5 S. Palislamovic 6 R. Shekhar Nokia 7 A. Lohiya 8 J. Drake 9 Juniper A. Sajassi 10 D. Cai 11 Cisco 13 Expires: January 8, 2017 July 7, 2016 15 Interconnect Solution for EVPN Overlay networks 16 draft-ietf-bess-dci-evpn-overlay-03 18 Abstract 20 This document describes how Network Virtualization Overlay networks 21 (NVO) can be connected to a Wide Area Network (WAN) in order to 22 extend the layer-2 connectivity required for some tenants. The 23 solution analyzes the interaction between NVO networks running EVPN 24 and other L2VPN technologies used in the WAN, such as VPLS/PBB-VPLS 25 or EVPN/PBB-EVPN, and proposes a solution for the interworking 26 between both. 28 Status of this Memo 30 This Internet-Draft is submitted in full conformance with the 31 provisions of BCP 78 and BCP 79. 33 Internet-Drafts are working documents of the Internet Engineering 34 Task Force (IETF), its areas, and its working groups. Note that 35 other groups may also distribute working documents as Internet- 36 Drafts. 38 Internet-Drafts are draft documents valid for a maximum of six months 39 and may be updated, replaced, or obsoleted by other documents at any 40 time. It is inappropriate to use Internet-Drafts as reference 41 material or to cite them other than as "work in progress." 43 The list of current Internet-Drafts can be accessed at 44 http://www.ietf.org/ietf/1id-abstracts.txt 46 The list of Internet-Draft Shadow Directories can be accessed at 47 http://www.ietf.org/shadow.html 49 This Internet-Draft will expire on January 8, 2017. 51 Copyright Notice 53 Copyright (c) 2016 IETF Trust and the persons identified as the 54 document authors. All rights reserved. 56 This document is subject to BCP 78 and the IETF Trust's Legal 57 Provisions Relating to IETF Documents 58 (http://trustee.ietf.org/license-info) in effect on the date of 59 publication of this document. Please review these documents 60 carefully, as they describe your rights and restrictions with respect 61 to this document. Code Components extracted from this document must 62 include Simplified BSD License text as described in Section 4.e of 63 the Trust Legal Provisions and are provided without warranty as 64 described in the Simplified BSD License. 66 Table of Contents 68 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 69 2. Decoupled Interconnect solution for EVPN overlay networks . . . 3 70 2.1. Interconnect requirements . . . . . . . . . . . . . . . . . 4 71 2.2. VLAN-based hand-off . . . . . . . . . . . . . . . . . . . . 5 72 2.3. PW-based (Pseudowire-based) hand-off . . . . . . . . . . . 5 73 2.4. Multi-homing solution on the GWs . . . . . . . . . . . . . 6 74 2.5. Gateway Optimizations . . . . . . . . . . . . . . . . . . . 6 75 2.5.1. MAC Address Advertisement Control . . . . . . . . . . . 6 76 2.5.2. ARP flooding control . . . . . . . . . . . . . . . . . 7 77 2.5.3. Handling failures between GW and WAN Edge routers . . . 7 78 3. Integrated Interconnect solution for EVPN overlay networks . . 8 79 3.1. Interconnect requirements . . . . . . . . . . . . . . . . . 8 80 3.2. VPLS Interconnect for EVPN-Overlay networks . . . . . . . . 9 81 3.2.1. Control/Data Plane setup procedures on the GWs . . . . 9 82 3.2.2. Multi-homing procedures on the GWs . . . . . . . . . . 10 83 3.3. PBB-VPLS Interconnect for EVPN-Overlay networks . . . . . . 10 84 3.3.1. Control/Data Plane setup procedures on the GWs . . . . 10 85 3.3.2. Multi-homing procedures on the GWs . . . . . . . . . . 11 86 3.4. EVPN-MPLS Interconnect for EVPN-Overlay networks . . . . . 11 87 3.4.1. Control Plane setup procedures on the GWs . . . . . . . 11 88 3.4.2. Data Plane setup procedures on the GWs . . . . . . . . 13 89 3.4.3. Multi-homing procedures on the GWs . . . . . . . . . . 14 90 3.4.4. Impact on MAC Mobility procedures . . . . . . . . . . . 15 91 3.4.5. Gateway optimizations . . . . . . . . . . . . . . . . . 15 92 3.4.6. Benefits of the EVPN-MPLS Interconnect solution . . . . 16 93 3.5. PBB-EVPN Interconnect for EVPN-Overlay networks . . . . . . 16 94 3.5.1. Control/Data Plane setup procedures on the GWs . . . . 17 95 3.5.2. Multi-homing procedures on the GWs . . . . . . . . . . 17 96 3.5.3. Impact on MAC Mobility procedures . . . . . . . . . . . 17 97 3.5.4. Gateway optimizations . . . . . . . . . . . . . . . . . 17 98 3.6. EVPN-VXLAN Interconnect for EVPN-Overlay networks . . . . . 18 99 3.6.1. Globally unique VNIs in the Interconnect network . . . 18 100 3.6.2. Downstream assigned VNIs in the Interconnect network . 19 101 5. Conventions and Terminology . . . . . . . . . . . . . . . . . . 19 102 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 20 103 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 20 104 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 20 105 8.1. Normative References . . . . . . . . . . . . . . . . . . . 20 106 8.2. Informative References . . . . . . . . . . . . . . . . . . 21 107 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 21 108 10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 21 109 11. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 21 111 1. Introduction 113 [EVPN-Overlays] discusses the use of EVPN as the control plane for 114 Network Virtualization Overlay (NVO) networks, where VXLAN, NVGRE or 115 MPLS over GRE can be used as possible data plane encapsulation 116 options. 118 While this model provides a scalable and efficient multi-tenant 119 solution within the Data Center, it might not be easily extended to 120 the WAN in some cases due to the requirements and existing deployed 121 technologies. For instance, a Service Provider might have an already 122 deployed (PBB-)VPLS or (PBB-)EVPN network that must be used to 123 interconnect Data Centers and WAN VPN users. A Gateway (GW) function 124 is required in these cases. 126 This document describes a Interconnect solution for EVPN overlay 127 networks, assuming that the NVO Gateway (GW) and the WAN Edge 128 functions can be decoupled in two separate systems or integrated into 129 the same system. The former option will be referred as "Decoupled 130 Interconnect solution" throughout the document, whereas the latter 131 one will be referred as "Integrated Interconnect solution". 133 2. Decoupled Interconnect solution for EVPN overlay networks 135 This section describes the interconnect solution when the GW and WAN 136 Edge functions are implemented in different systems. Figure 1 depicts 137 the reference model described in this section. 139 +--+ 140 |CE| 141 +--+ 142 | 143 +----+ 144 +----| PE |----+ 145 +---------+ | +----+ | +---------+ 146 +----+ | +---+ +----+ +----+ +---+ | +----+ 147 |NVE1|--| | | |WAN | |WAN | | | |--|NVE3| 148 +----+ | |GW1|--|Edge| |Edge|--|GW3| | +----+ 149 | +---+ +----+ +----+ +---+ | 150 | NVO-1 | | WAN | | NVO-2 | 151 | +---+ +----+ +----+ +---+ | 152 | | | |WAN | |WAN | | | | 153 +----+ | |GW2|--|Edge| |Edge|--|GW4| | +----+ 154 |NVE2|--| +---+ +----+ +----+ +---+ |--|NVE4| 155 +----+ +---------+ | | +---------+ +----+ 156 +--------------+ 158 |<-EVPN-Overlay-->|<-VLAN->|<-WAN L2VPN->|<--PW-->|<--EVPN-Overlay->| 159 hand-off hand-off 161 Figure 1 Decoupled Interconnect model 163 The following section describes the interconnect requirements for 164 this model. 166 2.1. Interconnect requirements 168 This proposed Interconnect architecture will be normally deployed in 169 networks where the EVPN-Overlay and WAN providers are different 170 entities and a clear demarcation is needed. The solution must observe 171 the following requirements: 173 o A simple connectivity hand-off must be provided between the EVPN- 174 Overlay network provider and the WAN provider so that QoS and 175 security enforcement are easily accomplished. 177 o The solution must be independent of the L2VPN technology deployed 178 in the WAN. 180 o Multi-homing between GW and WAN Edge routers is required. Per- 181 service load balancing MUST be supported. Per-flow load balancing 182 MAY be supported but it is not a strong requirement since a 183 deterministic path per service is usually required for an easy QoS 184 and security enforcement. 186 o Ethernet OAM and Connectivity Fault Management (CFM) functions must 187 be supported between the EVPN-Overlay network and the WAN network. 189 o The following optimizations MAY be supported at the GW: 190 + Flooding reduction of unknown unicast traffic sourced from the DC 191 Network Virtualization Edge devices (NVEs). 192 + Control of the WAN MAC addresses advertised to the DC. 193 + ARP flooding control for the requests coming from the WAN. 195 2.2. VLAN-based hand-off 197 In this option, the hand-off between the GWs and the WAN Edge routers 198 is based on 802.1Q VLANs. This is illustrated in Figure 1 (between 199 the GWs in NVO-1 and the WAN Edge routers). Each MAC-VRF in the GW is 200 connected to a different VSI/MAC-VRF instance in the WAN Edge router 201 by using a different C-TAG VLAN ID or a different combination of 202 S/C-TAG VLAN IDs that matches at both sides. 204 This option provides the best possible demarcation between the DC and 205 WAN providers and it does not require control plane interaction 206 between both providers. The disadvantage of this model is the 207 provisioning overhead since the service must be mapped to a S/C-TAG 208 VLAN ID combination at both, GW and WAN Edge routers. 210 In this model, the GW acts as a regular Network Virtualization Edge 211 (NVE) towards the DC. Its control plane, data plane procedures and 212 interactions are described in [EVPN-Overlays]. 214 The WAN Edge router acts as a (PBB-)VPLS or (PBB-)EVPN PE with 215 attachment circuits (ACs) to the GWs. Its functions are described in 216 [RFC4761][RFC4762][RFC6074] or [RFC7432][PBB-EVPN]. 218 2.3. PW-based (Pseudowire-based) hand-off 220 If MPLS can be enabled between the GW and the WAN Edge router, a PW- 221 based Interconnect solution can be deployed. In this option the 222 hand-off between both routers is based on FEC128-based PWs or FEC129- 223 based PWs (for a greater level of network automation). Note that this 224 model still provides a clear demarcation boundary between DC and WAN, 225 and security/QoS policies may be applied on a per PW basis. This 226 model provides better scalability than a C-TAG based hand-off and 227 less provisioning overhead than a combined C/S-TAG hand-off. The 228 PW-based hand-off interconnect is illustrated in Figure 1 (between 229 the NVO-2 GWs and the WAN Edge routers). 231 In this model, besides the usual MPLS procedures between GW and WAN 232 Edge router, the GW MUST support an interworking function in each 233 MAC-VRF that requires extension to the WAN: 235 o If a FEC128-based PW is used between the MAC-VRF (GW) and the VSI 236 (WAN Edge), the provisioning of the VCID for such PW MUST be 237 supported on the MAC-VRF and must match the VCID used in the peer 238 VSI at the WAN Edge router. 240 o If BGP Auto-discovery [RFC6074] and FEC129-based PWs are used 241 between the GW MAC-VRF and the WAN Edge VSI, the provisioning of 242 the VPLS-ID MUST be supported on the MAC-VRF and must match the 243 VPLS-ID used in the WAN Edge VSI. 245 2.4. Multi-homing solution on the GWs 247 As already discussed, single-active multi-homing, i.e. per-service 248 load-balancing multi-homing MUST be supported in this type of 249 interconnect. All-active multi-homing may be considered in future 250 revisions of this document. 252 The GWs will be provisioned with a unique ESI per WAN interconnect 253 and the hand-off attachment circuits or PWs between the GW and the 254 WAN Edge router will be assigned to such ESI. The ESI will be 255 administratively configured on the GWs according to the procedures in 256 [RFC7432]. This Interconnect ESI will be referred as "I-ESI" 257 hereafter. 259 The solution (on the GWs) MUST follow the single-active multi-homing 260 procedures as described in [EVPN-Overlays] for the provisioned I-ESI, 261 i.e. Ethernet A-D routes per ESI and per EVI will be advertised to 262 the DC NVEs. The MAC addresses learned (in the data plane) on the 263 hand-off links will be advertised with the I-ESI encoded in the ESI 264 field. 266 2.5. Gateway Optimizations 268 The following features MAY be supported on the GW in order to 269 optimize the control plane and data plane in the DC. 271 2.5.1. MAC Address Advertisement Control 273 The use of EVPN in the NVO networks brings a significant number of 274 benefits as described in [EVPN-Overlays]. However, if multiple DCs 275 are interconnected into a single EVI, each DC will have to import all 276 of the MAC addresses from each of the other DCs. 278 Even if optimized BGP techniques like RT-constraint are used, the 279 number of MAC addresses to advertise or withdraw (in case of failure) 280 by the GWs of a given DC could overwhelm the NVEs within that DC, 281 particularly when the NVEs reside in the hypervisors. 283 The solution specified in this document uses the 'Unknown MAC' route 284 which is advertised into a given DC by each of the DC's GWs. This 285 route is a regular EVPN MAC/IP Advertisement route in which the MAC 286 Address Length is set to 48, the MAC address is set to 287 00:00:00:00:00:00, the IP length is set to 0, and the ESI field is 288 set to the DC GW's I-ESI. 290 An NVE within that DC that understands the Unknown MAC route will 291 send (unicast) a packet with an unknown unicast MAC address to one of 292 the DCs GWs which will then forward that packet to the correct egress 293 PE. I.e., because the ESI is set to the DC GW's I-ESI, all-active 294 multi-homing can be applied to unknown unicast MAC addresses. 296 This document proposes that administrative policy determines whether 297 and which external MAC addresses and/or the Unknown MAC route are to 298 be advertised into a given DC. E.g., when all the DC MAC addresses 299 are learned in the control/management plane, it may be appropriate to 300 advertise the Unknown MAC route. 302 2.5.2. ARP flooding control 304 Another optimization mechanism, naturally provided by EVPN in the 305 GWs, is the Proxy ARP/ND function. The GWs SHOULD build a Proxy 306 ARP/ND cache table as per [RFC7432]. When the active GW receives an 307 ARP/ND request/solicitation coming from the WAN, the GW does a Proxy 308 ARP/ND table lookup and replies as long as the information is 309 available in its table. 311 This mechanism is especially recommended on the GWs since it protects 312 the DC network from external ARP/ND-flooding storms. 314 2.5.3. Handling failures between GW and WAN Edge routers 316 Link/PE failures MUST be handled on the GWs as specified in 317 [RFC7432]. The GW detecting the failure will withdraw the EVPN routes 318 as per [RFC7432]. 320 Individual AC/PW failures should be detected by OAM mechanisms. For 321 instance: 323 o If the Interconnect solution is based on a VLAN hand-off, 324 802.1ag/Y.1731 Ethernet-CFM MAY be used to detect individual AC 325 failures on both, the GW and WAN Edge router. An individual AC 326 failure will trigger the withdrawal of the corresponding A-D per 327 EVI route as well as the MACs learned on that AC. 329 o If the Interconnect solution is based on a PW hand-off, the LDP PW 330 Status bits TLV MAY be used to detect individual PW failures on 331 both, the GW and WAN Edge router. 333 3. Integrated Interconnect solution for EVPN overlay networks 335 When the DC and the WAN are operated by the same administrative 336 entity, the Service Provider can decide to integrate the GW and WAN 337 Edge PE functions in the same router for obvious CAPEX and OPEX 338 saving reasons. This is illustrated in Figure 2. Note that this model 339 does not provide an explicit demarcation link between DC and WAN 340 anymore. 342 +--+ 343 |CE| 344 +--+ 345 | 346 +----+ 347 +----| PE |----+ 348 +---------+ | +----+ | +---------+ 349 +----+ | +---+ +---+ | +----+ 350 |NVE1|--| | | | | |--|NVE3| 351 +----+ | |GW1| |GW3| | +----+ 352 | +---+ +---+ | 353 | NVO-1 | WAN | NVO-2 | 354 | +---+ +---+ | 355 | | | | | | 356 +----+ | |GW2| |GW4| | +----+ 357 |NVE2|--| +---+ +---+ |--|NVE4| 358 +----+ +---------+ | | +---------+ +----+ 359 +--------------+ 361 |<--EVPN-Overlay--->|<-----VPLS--->|<---EVPN-Overlay-->| 362 |<--PBB-VPLS-->| 363 Interconnect -> |<-EVPN-MPLS-->| 364 options |<--EVPN-Ovl-->| 365 |<--PBB-EVPN-->| 367 Figure 2 Integrated Interconnect model 369 3.1. Interconnect requirements 371 The solution must observe the following requirements: 373 o The GW function must provide control plane and data plane 374 interworking between the EVPN-overlay network and the L2VPN 375 technology supported in the WAN, i.e. (PBB-)VPLS or (PBB-)EVPN, as 376 depicted in Figure 2. 378 o Multi-homing MUST be supported. Single-active multi-homing with 379 per-service load balancing MUST be implemented. All-active multi- 380 homing, i.e. per-flow load-balancing, MUST be implemented as long 381 as the technology deployed in the WAN supports it. 383 o If EVPN is deployed in the WAN, the MAC Mobility, Static MAC 384 protection and other procedures (e.g. proxy-arp) described in 385 [RFC7432] must be supported end-to-end. 387 o Any type of inclusive multicast tree MUST be independently 388 supported in the WAN as per [RFC7432], and in the DC as per [EVPN- 389 Overlays]. 391 3.2. VPLS Interconnect for EVPN-Overlay networks 393 3.2.1. Control/Data Plane setup procedures on the GWs 395 Regular MPLS tunnels and TLDP/BGP sessions will be setup to the WAN 396 PEs and RRs as per [RFC4761][RFC4762][RFC6074] and overlay tunnels 397 and EVPN will be setup as per [EVPN-Overlays]. Note that different 398 route-targets for the DC and for the WAN are normally required. A 399 single type-1 RD per service may be used. 401 In order to support multi-homing, the GWs will be provisioned with an 402 I-ESI (see section 2.4), that will be unique per interconnection. All 403 the [RFC7432] procedures are still followed for the I-ESI, e.g. any 404 MAC address learned from the WAN will be advertised to the DC with 405 the I-ESI in the ESI field. 407 A MAC-VRF per EVI will be created in each GW. The MAC-VRF will have 408 two different types of tunnel bindings instantiated in two different 409 split-horizon-groups: 411 o VPLS PWs will be instantiated in the "WAN split-horizon-group". 413 o Overlay tunnel bindings (e.g. VXLAN, NVGRE) will be instantiated 414 in the "DC split-horizon-group". 416 Attachment circuits are also supported on the same MAC-VRF, but they 417 will not be part of any of the above split-horizon-groups. 419 Traffic received in a given split-horizon-group will never be 420 forwarded to a member of the same split-horizon-group. 422 As far as BUM flooding is concerned, a flooding list will be created 423 with the sub-list created by the inclusive multicast routes and the 424 sub-list created for VPLS in the WAN. BUM frames received from a 425 local attachment circuit will be flooded to both sub-lists. BUM 426 frames received from the DC or the WAN will be forwarded to the 427 flooding list observing the split-horizon-group rule described above. 429 Note that the GWs are not allowed to have an EVPN binding and a PW to 430 the same far-end within the same MAC-VRF in order to avoid loops and 431 packet duplication. This is described in [EVPN-VPLS-INTEGRATION]. 433 The optimizations procedures described in section 2.5 can also be 434 applied to this model. 436 3.2.2. Multi-homing procedures on the GWs 438 Single-active multi-homing MUST be supported on the GWs. All-active 439 multi-homing is not supported by VPLS. 441 All the single-active multi-homing procedures as described by [EVPN- 442 Overlays] will be followed for the I-ESI. 444 The non-DF GW for the I-ESI will block the transmission and reception 445 of all the bindings in the "WAN split-horizon-group" for BUM and 446 unicast traffic. 448 3.3. PBB-VPLS Interconnect for EVPN-Overlay networks 450 3.3.1. Control/Data Plane setup procedures on the GWs 452 In this case, there is no impact on the procedures described in 453 [RFC7041] for the B-component. However the I-component instances 454 become EVI instances with EVPN-Overlay bindings and potentially local 455 attachment circuits. M MAC-VRF instances can be multiplexed into the 456 same B-component instance. This option provides significant savings 457 in terms of PWs to be maintained in the WAN. 459 The I-ESI concept described in section 3.2.1 will also be used for 460 the PBB-VPLS-based Interconnect. 462 B-component PWs and I-component EVPN-overlay bindings established to 463 the same far-end will be compared. The following rules will be 464 observed: 466 o Attempts to setup a PW between the two GWs within the B- 467 component context will never be blocked. 469 o If a PW exists between two GWs for the B-component and an 470 attempt is made to setup an EVPN binding on an I-component linked 471 to that B-component, the EVPN binding will be kept operationally 472 down. Note that the BGP EVPN routes will still be valid but not 473 used. 475 o The EVPN binding will only be up and used as long as there is no 476 PW to the same far-end in the corresponding B-component. The EVPN 477 bindings in the I-components will be brought down before the PW in 478 the B-component is brought up. 480 The optimizations procedures described in section 2.5 can also be 481 applied to this Interconnect option. 483 3.3.2. Multi-homing procedures on the GWs 485 Single-active multi-homing MUST be supported on the GWs. 487 All the single-active multi-homing procedures as described by [EVPN- 488 Overlays] will be followed for the I-ESI for each EVI instance 489 connected to B-component. 491 3.4. EVPN-MPLS Interconnect for EVPN-Overlay networks 493 If EVPN for MPLS tunnels, EVPN-MPLS hereafter, is supported in the 494 WAN, an end-to-end EVPN solution can be deployed. The following 495 sections describe the proposed solution as well as the impact 496 required on the [RFC7432] procedures. 498 3.4.1. Control Plane setup procedures on the GWs 500 The GWs MUST establish separate BGP sessions for sending/receiving 501 EVPN routes to/from the DC and to/from the WAN. Normally each GW will 502 setup one (two) BGP EVPN session(s) to the DC RR(s) and one(two) 503 session(s) to the WAN RR(s). 505 In order to facilitate separate BGP processes for DC and WAN, EVPN 506 routes sent to the WAN SHOULD carry a different route-distinguisher 507 (RD) than the EVPN routes sent to the DC. In addition, although 508 reusing the same value is possible, different route-targets are 509 expected to be handled for the same EVI in the WAN and the DC. Note 510 that the EVPN service routes sent to the DC RRs will normally include 511 a [RFC5512] BGP encapsulation extended community with a different 512 tunnel type than the one sent to the WAN RRs. 514 As in the other discussed options, an I-ESI will be configured on the 515 GWs for multi-homing. This I-ESI represents the WAN to the DC but 516 also the DC to the WAN. Optionally, different I-ESI values MAY be 517 configured for representing the WAN and the DC, as long as the I-ESI 518 values are consistently configured on the redundant GWs and the same 519 GW becomes DF for both I-ESIs. 521 Received EVPN routes will never be reflected on the GWs but consumed 522 and re-advertised (if needed): 524 o Ethernet A-D routes, ES routes and Inclusive Multicast routes 525 are consumed by the GWs and processed locally for the 526 corresponding [RFC7432] procedures. 528 o MAC/IP advertisement routes will be received, imported and if 529 they become active in the MAC-VRF MAC FIB, the information will 530 be re-advertised as new routes with the following fields: 532 + The RD will be the GW's RD for the MAC-VRF. 534 + The ESI will be set to the I-ESI. 536 + The Ethernet-tag value will be kept from the received NLRI. 538 + The MAC length, MAC address, IP Length and IP address values 539 will be kept from the received NLRI. 541 + The MPLS label will be a local 20-bit value (when sent to the 542 WAN) or a DC-global 24-bit value (when sent to the DC). 544 + The appropriate Route-Targets (RTs) and [RFC5512] BGP 545 Encapsulation extended community will be used according to 546 [EVPN-Overlays]. 548 The GWs will also generate the following local EVPN routes that will 549 be sent to the DC and WAN, with their corresponding RTs and [RFC5512] 550 BGP Encapsulation extended community values: 552 o ES route for the I-ESI. 554 o Ethernet A-D routes per ESI and EVI for the I-ESI. The A-D per- 555 EVI routes sent to the WAN and the DC will have a consistent 556 Ethernet-Tag values. 558 o Inclusive Multicast routes with independent tunnel type value 559 for the WAN and DC. E.g. a P2MP LSP may be used in the WAN 560 whereas ingress replication may be used in the DC. The routes 561 sent to the WAN and the DC will have a consistent Ethernet-Tag. 563 o MAC/IP advertisement routes for MAC addresses learned in local 564 attachment circuits. Note that these routes will not include the 565 I-ESI, but ESI=0 or different from 0 for local Ethernet Segments 566 (ES). The routes sent to the WAN and the DC will have a 567 consistent Ethernet-Tag. 569 Assuming GW1 and GW2 are peer GWs of the same DC, each GW will 570 generate two sets of local service routes: Set-DC will be sent to the 571 DC RRs and will include A-D per EVI, Inclusive Multicast and MAC/IP 572 routes for the DC encapsulation and RT. Set-WAN will be sent to the 573 WAN RRs and will include the same routes but using the WAN RT and 574 encapsulation. GW1 and GW2 will receive each other's set-DC and set- 575 WAN. This is the expected behavior on GW1 and GW2 for locally 576 generated routes: 578 o Inclusive multicast routes: when setting up the flooding lists 579 for a given MAC-VRF, each GW will include its DC peer GW only in 580 the EVPN-overlay flooding list (by default) and not the EVPN- 581 MPLS flooding list. That is, GW2 will import two Inclusive 582 Multicast routes from GW1 (from set-DC and set-WAN) but will 583 only consider one of the two, having the set-DC route higher 584 priority. An administrative option MAY change this preference so 585 that the set-WAN route is selected first. 587 o MAC/IP advertisement routes for local attachment circuits: as 588 above, the GW will select only one, having the route from the 589 set-DC a higher priority. As for the Inclusive multicast routes, 590 an administrative option MAY change this priority. 592 Note that, irrespective of the encapsulation, EVPN routes always have 593 higher priority than VPLS AD routes as per [EVPN-VPLS-INTEGRATION]. 595 3.4.2. Data Plane setup procedures on the GWs 597 The procedure explained at the end of the previous section will make 598 sure there are no loops or packet duplication between the GWs of the 599 same DC (for frames generated from local ACs) since only one EVPN 600 binding per EVI will be setup in the data plane between the two 601 nodes. That binding will by default be added to the EVPN-overlay 602 flooding list. 604 As for the rest of the EVPN tunnel bindings, they will be added to 605 one of the two flooding lists that each GW sets up for the same MAC- 606 VRF: 608 o EVPN-overlay flooding list (composed of bindings to the remote 609 NVEs or multicast tunnel to the NVEs). 611 o EVPN-MPLS flooding list (composed of MP2P or LSM tunnel to the 612 remote PEs) 614 Each flooding list will be part of a separate split-horizon-group: 615 the WAN split-horizon-group or the DC split-horizon-group. Traffic 616 generated from a local AC can be flooded to both 617 split-horizon-groups. Traffic from a binding of a split-horizon-group 618 can be flooded to the other split-horizon-group and local ACs, but 619 never to a member of its own split-horizon-group. 621 When either GW1 or GW2 receive a BUM frame on an overlay tunnel, they 622 will perform a tunnel IP SA lookup to determine if the packet's 623 origin is the peer DC GW, i.e. GW2 or GW1 respectively. If the packet 624 is coming from the peer DC GW, it MUST only be flooded to local 625 attachment circuits and not to the WAN split-horizon-group (the 626 assumption is that the peer GW would have sent the BUM packet to the 627 WAN directly). 629 3.4.3. Multi-homing procedures on the GWs 631 Single-active as well as all-active multi-homing MUST be supported. 633 All the multi-homing procedures as described by [RFC7432] will be 634 followed for the DF election for I-ESI, as well as the backup-path 635 (single-active) and aliasing (all-active) procedures on the remote 636 PEs/NVEs. The following changes are required at the GW with respect 637 to the I-ESI: 639 o Single-active multi-homing; assuming a WAN split-horizon-group, 640 a DC split-horizon-group and local ACs on the GWs: 642 + Forwarding behavior on the non-DF: the non-DF MUST NOT forward 643 BUM or unicast traffic received from a given split-horizon- 644 group to a member of its own split-horizon-group or to the 645 other split-horizon-group. Only forwarding to local ACs is 646 allowed (as long as they are not part of an ES for which the 647 node is non-DF). 649 + Forwarding behavior on the DF: the DF MUST NOT forward BUM or 650 unicast traffic received from a given split-horizon-group to a 651 member of his own split-horizon group or to the non-DF. 652 Forwarding to the other split-horizon-group (except the non- 653 DF) and local ACs is allowed (as long as the ACs are not part 654 of an ES for which the node is non-DF). 656 o All-active multi-homing; assuming a WAN split-horizon-group, a 657 DC split-horizon-group and local ACs on the GWs: 659 + Forwarding behavior on the non-DF: the non-DF follows the same 660 behavior as the non-DF in the single-active case but only for 661 BUM traffic. Unicast traffic received from a split-horizon- 662 group MUST NOT be forwarded to a member of its own split- 663 horizon-group but can be forwarded normally to the other 664 split-horizon-group and local ACs. If a known unicast packet 665 is identified as a "flooded" packet, the procedures for BUM 666 traffic MUST be followed. 668 + Forwarding behavior on the DF: the DF follows the same 669 behavior as the DF in the single-active case but only for BUM 670 traffic. Unicast traffic received from a split-horizon-group 671 MUST NOT be forwarded to a member of its own split-horizon- 672 group but can be forwarded normally to the other split- 673 horizon-group and local ACs. If a known unicast packet is 674 identified as a "flooded" packet, the procedures for BUM 675 traffic MUST be followed. 677 o No ESI label is required to be signaled for I-ESI for its use by 678 the non-DF in the data path. This is possible because the non-DF 679 and the DF will never forward BUM traffic (coming from a split- 680 horizon-group) to each other. 682 3.4.4. Impact on MAC Mobility procedures 684 MAC Mobility procedures described in [RFC7432] are not modified by 685 this document. 687 Note that an intra-DC MAC move still leaves the MAC attached to the 688 same I-ESI, so under the rules of [RFC7432] this is not considered a 689 MAC mobility event. Only when the MAC moves from the WAN domain to 690 the DC domain (or from one DC to another) the MAC will be learned 691 from a different ES and the MAC Mobility procedures will kick in. 693 The sticky bit indication in the MAC Mobility extended community MUST 694 be propagated between domains. 696 3.4.5. Gateway optimizations 698 All the Gateway optimizations described in section 2.5 MAY be applied 699 to the GWs when the Interconnect is based on EVPN-MPLS. 701 In particular, the use of the Unknown MAC route, as described in 702 section 2.5.1, solves some transient packet duplication issues in 703 cases of all-active multi-homing, as explained below. 705 Consider the diagram in Figure 2 for EVPN-MPLS Interconnect and all- 706 active multi-homing, and the following sequence: 708 a) MAC Address M1 is advertised from NVE3 in EVI-1. 710 b) GW3 and GW4 learn M1 for EVI-1 and re-advertise M1 to the WAN 711 with I-ESI-2 in the ESI field. 713 c) GW1 and GW2 learn M1 and install GW3/GW4 as next-hops following 714 the EVPN aliasing procedures. 716 d) Before NVE1 learns M1, a packet arrives at NVE1 with 717 destination M1. If the Unknown MAC route had not been 718 advertised into the DC, NVE1 would have flooded the packet 719 throughout the DC, in particular to both GW1 and GW2. If the 720 same VNI/VSID is used for both known unicast and BUM traffic, 721 as is typically the case, there is no indication in the packet 722 that it is a BUM packet and both GW1 and GW2 would have 723 forwarded it. However, because the Unknown MAC route had been 724 advertised into the DC, NVE1 will unicast the packet to either 725 GW1 or GW2. 727 e) Since both GW1 and GW2 know M1, the GW receiving the packet 728 will forward it to either GW3 or GW4. 730 3.4.6. Benefits of the EVPN-MPLS Interconnect solution 732 Besides retaining the EVPN attributes between Data Centers and 733 throughout the WAN, the EVPN-MPLS Interconnect solution on the GWs 734 has some benefits compared to pure BGP EVPN RR or Inter-AS model B 735 solutions without a gateway: 737 o The solution supports the connectivity of local attachment 738 circuits on the GWs. 740 o Different data plane encapsulations can be supported in the DC 741 and the WAN. 743 o Optimized multicast solution, with independent inclusive 744 multicast trees in DC and WAN. 746 o MPLS Label aggregation: for the case where MPLS labels are 747 signaled from the NVEs for MAC/IP Advertisement routes, this 748 solution provides label aggregation. A remote PE MAY receive a 749 single label per GW MAC-VRF as opposed to a label per NVE/MAC- 750 VRF connected to the GW MAC-VRF. For instance, in Figure 2, PE 751 would receive only one label for all the routes advertised for a 752 given MAC-VRF from GW1, as opposed to a label per NVE/MAC-VRF. 754 o The GW will not propagate MAC mobility for the MACs moving 755 within a DC. Mobility intra-DC is solved by all the NVEs in the 756 DC. The MAC Mobility procedures on the GWs are only required in 757 case of mobility across DCs. 759 o Proxy-ARP/ND function on the DC GWs can be leveraged to reduce 760 ARP/ND flooding in the DC or/and in the WAN. 762 3.5. PBB-EVPN Interconnect for EVPN-Overlay networks 764 [PBB-EVPN] is yet another Interconnect option. It requires the use of 765 GWs where I-components and associated B-components are EVI 766 instances. 768 3.5.1. Control/Data Plane setup procedures on the GWs 770 EVPN will run independently in both components, the I-component MAC- 771 VRF and B-component MAC-VRF. Compared to [PBB-EVPN], the DC C-MACs 772 are no longer learned in the data plane on the GW but in the control 773 plane through EVPN running on the I-component. Remote C-MACs coming 774 from remote PEs are still learned in the data plane. B-MACs in the B- 775 component will be assigned and advertised following the procedures 776 described in [PBB-EVPN]. 778 An I-ESI will be configured on the GWs for multi-homing, but it will 779 only be used in the EVPN control plane for the I-component EVI. No 780 non-reserved ESIs will be used in the control plane of the B- 781 component EVI as per [PBB-EVPN]. 783 The rest of the control plane procedures will follow [RFC7432] for 784 the I-component EVI and [PBB-EVPN] for the B-component EVI. 786 From the data plane perspective, the I-component and B-component EVPN 787 bindings established to the same far-end will be compared and the I- 788 component EVPN-overlay binding will be kept down following the rules 789 described in section 3.3.1. 791 3.5.2. Multi-homing procedures on the GWs 793 Single-active as well as all-active multi-homing MUST be supported. 795 The forwarding behavior of the DF and non-DF will be changed based on 796 the description outlined in section 3.4.3, only replacing the "WAN 797 split-horizon-group" for the B-component. 799 3.5.3. Impact on MAC Mobility procedures 801 C-MACs learned from the B-component will be advertised in EVPN within 802 the I-component EVI scope. If the C-MAC was previously known in the 803 I-component database, EVPN would advertise the C-MAC with a higher 804 sequence number, as per [RFC7432]. From a Mobility perspective and 805 the related procedures described in [RFC7432], the C-MACs learned 806 from the B-component are considered local. 808 3.5.4. Gateway optimizations 810 All the considerations explained in section 3.4.5 are applicable to 811 the PBB-EVPN Interconnect option. 813 3.6. EVPN-VXLAN Interconnect for EVPN-Overlay networks 815 If EVPN for Overlay tunnels is supported in the WAN and a GW function 816 is required, an end-to-end EVPN solution can be deployed. This 817 section focuses on the specific case of EVPN for VXLAN (EVPN-VXLAN 818 hereafter) and the impact on the [RFC7432] procedures. 820 This use-case assumes that NVEs need to use the VNIs or VSIDs as a 821 globally unique identifiers within a data center, and a Gateway needs 822 to be employed at the edge of the data center network to translate 823 the VNI or VSID when crossing the network boundaries. This GW 824 function provides VNI and tunnel IP address translation. The use-case 825 in which local downstream assigned VNIs or VSIDs can be used (like 826 MPLS labels) is described by [EVPN-Overlays]. 828 While VNIs are globally significant within each DC, there are two 829 possibilities in the Interconnect network: 831 a) Globally unique VNIs in the Interconnect network: 832 In this case, the GWs and PEs in the Interconnect network will 833 agree on a common VNI for a given EVI. The RT to be used in the 834 Interconnect network can be auto-derived from the agreed 835 Interconnect VNI. The VNI used inside each DC MAY be the same 836 as the Interconnect VNI. 838 b) Downstream assigned VNIs in the Interconnect network. 839 In this case, the GWs and PEs MUST use the proper RTs to 840 import/export the EVPN routes. Note that even if the VNI is 841 downstream assigned in the Interconnect network, and unlike 842 option B, it only identifies the pair and 843 not the pair. The VNI used inside 844 each DC MAY be the same as the Interconnect VNI. GWs SHOULD 845 support multiple VNI spaces per EVI (one per Interconnect 846 network they are connected to). 848 In both options, NVEs inside a DC only have to be aware of a single 849 VNI space, and only GWs will handle the complexity of managing 850 multiple VNI spaces. In addition to VNI translation above, the GWs 851 will provide translation of the tunnel source IP for the packets 852 generated from the NVEs, using their own IP address. GWs will use 853 that IP address as the BGP next-hop in all the EVPN updates to the 854 Interconnect network. 856 The following sections provide more details about these two options. 858 3.6.1. Globally unique VNIs in the Interconnect network 860 Considering Figure 2, if a host H1 in NVO-1 needs to communicate with 861 a host H2 in NVO-2, and assuming that different VNIs are used in each 862 DC for the same EVI, e.g. VNI-10 in NVO-1 and VNI-20 in NVO-2, then 863 the VNIs must be translated to a common Interconnect VNI (e.g. VNI- 864 100) on the GWs. Each GW is provisioned with a VNI translation 865 mapping so that it can translate the VNI in the control plane when 866 sending BGP EVPN route updates to the Interconnect network. In other 867 words, GW1 and GW2 must be configured to map VNI-10 to VNI-100 in the 868 BGP update messages for H1's MAC route. This mapping is also used to 869 translate the VNI in the data plane in both directions, that is, VNI- 870 10 to VNI-100 when the packet is received from NVO-1 and the reverse 871 mapping from VNI-100 to VNI-10 when the packet is received from the 872 remote NVO-2 network and needs to be forwarded to NVO-1. 874 The procedures described in section 3.4 will be followed, considering 875 that the VNIs advertised/received by the GWs will be translated 876 accordingly. 878 3.6.2. Downstream assigned VNIs in the Interconnect network 880 In this case, if a host H1 in NVO-1 needs to communicate with a host 881 H2 in NVO-2, and assuming that different VNIs are used in each DC for 882 the same EVI, e.g. VNI-10 in NVO-1 and VNI-20 in NVO-2, then the VNIs 883 must be translated as in section 3.6.1. However, in this case, there 884 is no need to translate to a common Interconnect VNI on the GWs. Each 885 GW can translate the VNI received in an EVPN update to a locally 886 assigned VNI advertised to the Interconnect network. Each GW can use 887 a different Interconnect VNI, hence this VNI does not need to be 888 agreed on all the GWs and PEs of the Interconnect network. 890 The procedures described in section 3.4 will be followed, taking the 891 considerations above for the VNI translation. 893 5. Conventions and Terminology 895 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 896 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 897 document are to be interpreted as described in RFC-2119 [RFC2119]. 899 AC: Attachment Circuit 901 BUM: it refers to the Broadcast, Unknown unicast and Multicast 902 traffic 904 DF: Designated Forwarder 906 GW: Gateway or Data Center Gateway 908 DCI: Data Center Interconnect 909 ES: Ethernet Segment 911 ESI: Ethernet Segment Identifier 913 I-ESI: Interconnect ESI defined on the GWs for multi-homing to/from 914 the WAN 916 EVI: EVPN Instance 918 MAC-VRF: it refers to an EVI instance in a particular node 920 NVE: Network Virtualization Edge 922 PW: Pseudowire 924 RD: Route-Distinguisher 926 RT: Route-Target 928 TOR: Top-Of-Rack switch 930 VNI/VSID: refers to VXLAN/NVGRE virtual identifiers 932 VSI: Virtual Switch Instance or VPLS instance in a particular PE 934 6. Security Considerations 936 This section will be completed in future versions. 938 7. IANA Considerations 940 8. References 942 8.1. Normative References 944 [RFC4761]Kompella, K., Ed., and Y. Rekhter, Ed., "Virtual Private LAN 945 Service (VPLS) Using BGP for Auto-Discovery and Signaling", RFC 4761, 946 DOI 10.17487/RFC4761, January 2007, . 949 [RFC4762]Lasserre, M., Ed., and V. Kompella, Ed., "Virtual Private 950 LAN Service (VPLS) Using Label Distribution Protocol (LDP) 951 Signaling", RFC 4762, DOI 10.17487/RFC4762, January 2007, 952 . 954 [RFC6074]Rosen, E., Davie, B., Radoaca, V., and W. Luo, 955 "Provisioning, Auto-Discovery, and Signaling in Layer 2 Virtual 956 Private Networks (L2VPNs)", RFC 6074, DOI 10.17487/RFC6074, January 957 2011, . 959 [RFC7041]Balus, F., Ed., Sajassi, A., Ed., and N. Bitar, Ed., 960 "Extensions to the Virtual Private LAN Service (VPLS) Provider Edge 961 (PE) Model for Provider Backbone Bridging", RFC 7041, DOI 962 10.17487/RFC7041, November 2013, . 965 [RFC7432]Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A., 966 Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based Ethernet 967 VPN", RFC 7432, DOI 10.17487/RFC7432, February 2015, . 970 [RFC7623] Sajassi et al., "Provider Backbone Bridging Combined with 971 Ethernet VPN (PBB-EVPN)", RFC 7623, September, 2015, . 974 8.2. Informative References 976 [EVPN-Overlays] Sajassi-Drake et al., "A Network Virtualization 977 Overlay Solution using EVPN", draft-ietf-bess-evpn-overlay-02.txt, 978 work in progress, October, 2015 980 [EVPN-VPLS-INTEGRATION] Sajassi et al., "(PBB-)EVPN Seamless 981 Integration with (PBB-)VPLS", draft-ietf-bess-evpn-vpls-integration- 982 00.txt, work in progress, February, 2015 984 9. Acknowledgments 986 The authors would like to thank Neil Hart for their valuable comments 987 and feedback. 989 10. Contributors 991 In addition to the authors listed on the front page, the following 992 co-authors have also contributed to this document: 994 Florin Balus 995 Wen Lin 997 11. Authors' Addresses 998 Jorge Rabadan 999 Nokia 1000 777 E. Middlefield Road 1001 Mountain View, CA 94043 USA 1002 Email: jorge.rabadan@nokia.com 1004 Senthil Sathappan 1005 Nokia 1006 Email: senthil.sathappan@nokia.com 1008 Wim Henderickx 1009 Nokia 1010 Email: wim.henderickx@nokia.com 1012 Senad Palislamovic 1013 Nokia 1014 Email: senad.palislamovic@nokia.com 1016 Ali Sajassi 1017 Cisco 1018 Email: sajassi@cisco.com 1020 Ravi Shekhar 1021 Juniper 1022 Email: rshekhar@juniper.net 1024 Anil Lohiya 1025 Juniper 1026 Email: alohiya@juniper.net 1028 Dennis Cai 1029 Cisco Systems 1030 Email: dcai@cisco.com 1032 John Drake 1033 Juniper 1034 Email: jdrake@juniper.net