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Summary: 1 error (**), 0 flaws (~~), 9 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 Alcatel-Lucent 7 A. Lohiya 8 Juniper F. Balus 9 Nuage Networks 11 A. Sajassi 12 D. Cai 13 Cisco 15 Expires: July 20, 2015 January 16, 2015 17 Interconnect Solution for EVPN Overlay networks 18 draft-ietf-bess-dci-evpn-overlay-00 20 Abstract 22 This document describes how Network Virtualization Overlay networks 23 (NVO) can be connected to a Wide Area Network (WAN) in order to 24 extend the layer-2 connectivity required for some tenants. The 25 solution analyzes the interaction between NVO networks running EVPN 26 and other L2VPN technologies used in the WAN, such as VPLS/PBB-VPLS 27 or EVPN/PBB-EVPN, and proposes a solution for the interworking 28 between both. 30 Status of this Memo 32 This Internet-Draft is submitted in full conformance with the 33 provisions of BCP 78 and BCP 79. 35 Internet-Drafts are working documents of the Internet Engineering 36 Task Force (IETF), its areas, and its working groups. Note that 37 other groups may also distribute working documents as Internet- 38 Drafts. 40 Internet-Drafts are draft documents valid for a maximum of six months 41 and may be updated, replaced, or obsoleted by other documents at any 42 time. It is inappropriate to use Internet-Drafts as reference 43 material or to cite them other than as "work in progress." 45 The list of current Internet-Drafts can be accessed at 46 http://www.ietf.org/ietf/1id-abstracts.txt 47 The list of Internet-Draft Shadow Directories can be accessed at 48 http://www.ietf.org/shadow.html 50 This Internet-Draft will expire on July 20, 2015. 52 Copyright Notice 54 Copyright (c) 2015 IETF Trust and the persons identified as the 55 document authors. All rights reserved. 57 This document is subject to BCP 78 and the IETF Trust's Legal 58 Provisions Relating to IETF Documents 59 (http://trustee.ietf.org/license-info) in effect on the date of 60 publication of this document. Please review these documents 61 carefully, as they describe your rights and restrictions with respect 62 to this document. Code Components extracted from this document must 63 include Simplified BSD License text as described in Section 4.e of 64 the Trust Legal Provisions and are provided without warranty as 65 described in the Simplified BSD License. 67 Table of Contents 69 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 70 2. Decoupled Interconnect solution for EVPN overlay networks . . . 3 71 2.1. Interconnect requirements . . . . . . . . . . . . . . . . . 4 72 2.2. VLAN-based hand-off . . . . . . . . . . . . . . . . . . . . 5 73 2.3. PW-based (Pseudowire-based) hand-off . . . . . . . . . . . 5 74 2.4. Multi-homing solution on the GWs . . . . . . . . . . . . . 6 75 2.5. Gateway Optimizations . . . . . . . . . . . . . . . . . . . 6 76 2.5.1 Use of the Unknown MAC route to reduce unknown 77 flooding . . . . . . . . . . . . . . . . . . . . . . . . 6 78 2.5.2. MAC address advertisement control . . . . . . . . . . . 7 79 2.5.3. ARP flooding control . . . . . . . . . . . . . . . . . 7 80 2.5.4. Handling failures between GW and WAN Edge routers . . . 7 81 3. Integrated Interconnect solution for EVPN overlay networks . . 8 82 3.1. Interconnect requirements . . . . . . . . . . . . . . . . . 9 83 3.2. VPLS Interconnect for EVPN-Overlay networks . . . . . . . . 10 84 3.2.1. Control/Data Plane setup procedures on the GWs . . . . 10 85 3.2.2. Multi-homing procedures on the GWs . . . . . . . . . . 10 86 3.3. PBB-VPLS Interconnect for EVPN-Overlay networks . . . . . . 11 87 3.3.1. Control/Data Plane setup procedures on the GWs . . . . 11 88 3.3.2. Multi-homing procedures on the GWs . . . . . . . . . . 11 89 3.4. EVPN-MPLS Interconnect for EVPN-Overlay networks . . . . . 12 90 3.4.1. Control Plane setup procedures on the GWs . . . . . . . 12 91 3.4.2. Data Plane setup procedures on the GWs . . . . . . . . 13 92 3.4.3. Multi-homing procedures on the GWs . . . . . . . . . . 14 93 3.4.4. Impact on MAC Mobility procedures . . . . . . . . . . . 15 94 3.4.5. Gateway optimizations . . . . . . . . . . . . . . . . . 15 95 3.4.6. Benefits of the EVPN-MPLS Interconnect solution . . . . 16 96 3.5. PBB-EVPN Interconnect for EVPN-Overlay networks . . . . . . 17 97 3.5.1. Control/Data Plane setup procedures on the GWs . . . . 17 98 3.5.2. Multi-homing procedures on the GWs . . . . . . . . . . 17 99 3.5.3. Impact on MAC Mobility procedures . . . . . . . . . . . 18 100 3.5.4. Gateway optimizations . . . . . . . . . . . . . . . . . 18 101 3.6. EVPN-VXLAN Interconnect for EVPN-Overlay networks . . . . . 18 102 3.6.1. Globally unique VNIs in the Interconnect network . . . 19 103 3.6.2. Downstream assigned VNIs in the Interconnect network . 19 104 5. Conventions and Terminology . . . . . . . . . . . . . . . . . . 20 105 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 20 106 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 20 107 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21 108 8.1. Normative References . . . . . . . . . . . . . . . . . . . 21 109 8.2. Informative References . . . . . . . . . . . . . . . . . . 21 110 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 21 111 10. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 21 113 1. Introduction 115 [EVPN-Overlays] discusses the use of EVPN as the control plane for 116 Network Virtualization Overlay (NVO) networks, where VXLAN, NVGRE or 117 MPLS over GRE can be used as possible data plane encapsulation 118 options. 120 While this model provides a scalable and efficient multi-tenant 121 solution within the Data Center, it might not be easily extended to 122 the WAN in some cases due to the requirements and existing deployed 123 technologies. For instance, a Service Provider might have an already 124 deployed (PBB-)VPLS or (PBB-)EVPN network that must be used to 125 interconnect Data Centers and WAN VPN users. A Gateway (GW) function 126 is required in these cases. 128 This document describes a Interconnect solution for EVPN overlay 129 networks, assuming that the NVO Gateway (GW) and the WAN Edge 130 functions can be decoupled in two separate systems or integrated into 131 the same system. The former option will be referred as "Decoupled 132 Interconnect solution" throughout the document whereas the latter one 133 will be referred as "Integrated Interconnect solution". 135 2. Decoupled Interconnect solution for EVPN overlay networks 137 This section describes the interconnect solution when the GW and WAN 138 Edge functions are implemented in different systems. Figure 1 depicts 139 the reference model described in this section. 141 +--+ 142 |CE| 143 +--+ 144 | 145 +----+ 146 +----| PE |----+ 147 +---------+ | +----+ | +---------+ 148 +----+ | +---+ +----+ +----+ +---+ | +----+ 149 |NVE1|--| | | |WAN | |WAN | | | |--|NVE3| 150 +----+ | |GW1|--|Edge| |Edge|--|GW3| | +----+ 151 | +---+ +----+ +----+ +---+ | 152 | NVO-1 | | WAN | | NVO-2 | 153 | +---+ +----+ +----+ +---+ | 154 | | | |WAN | |WAN | | | | 155 +----+ | |GW2|--|Edge| |Edge|--|GW4| | +----+ 156 |NVE2|--| +---+ +----+ +----+ +---+ |--|NVE4| 157 +----+ +---------+ | | +---------+ +----+ 158 +--------------+ 160 |<-EVPN-Overlay-->|<-VLAN->|<-WAN L2VPN->|<--PW-->|<--EVPN-Overlay->| 161 hand-off hand-off 163 Figure 1 Decoupled Interconnect model 165 The following section describes the interconnect requirements for 166 this model. 168 2.1. Interconnect requirements 170 This proposed Interconnect architecture will be normally deployed in 171 networks where the EVPN-Overlay and WAN providers are different 172 entities and a clear demarcation is needed. The solution must observe 173 the following requirements: 175 o A simple connectivity hand-off must be provided between the EVPN- 176 Overlay network provider and the WAN provider so that QoS and 177 security enforcement are easily accomplished. 179 o The solution must be independent of the L2VPN technology deployed 180 in the WAN. 182 o Multi-homing between GW and WAN Edge routers is required. Per- 183 service load balancing MUST be supported. Per-flow load balancing 184 MAY be supported but it is not a strong requirement since a 185 deterministic path per service is usually required for an easy QoS 186 and security enforcement. 188 o Ethernet OAM and Connectivity Fault Management (CFM) functions must 189 be supported between the EVPN-Overlay network and the WAN network. 191 o The following optimizations MAY be supported at the GW: 192 + Flooding reduction of unknown unicast traffic sourced from the DC 193 Network Virtualization Edge devices (NVEs). 194 + Control of the WAN MAC addresses advertised to the DC. 195 + ARP flooding control for the requests coming from the WAN. 197 2.2. VLAN-based hand-off 199 In this option, the hand-off between the GWs and the WAN Edge routers 200 is based on 802.1Q VLANs. This is illustrated in Figure 1 (between 201 the GWs in NVO-1 and the WAN Edge routers). Each MAC-VRF in the GW is 202 connected to a different VSI/MAC-VRF instance in the WAN Edge router 203 by using a different C-TAG VLAN ID or a different combination of 204 S/C-TAG VLAN IDs that matches at both sides. 206 This option provides the best possible demarcation between the DC and 207 WAN providers and it does not require control plane interaction 208 between both providers. The disadvantage of this model is the 209 provisioning overhead since the service must be mapped to a S/C-TAG 210 VLAN ID combination at both, GW and WAN Edge routers. 212 In this model, the GW acts as a regular Network Virtualization Edge 213 (NVE) towards the DC. Its control plane, data plane procedures and 214 interactions are described in [EVPN-Overlays]. 216 The WAN Edge router acts as a (PBB-)VPLS or (PBB-)EVPN PE with 217 attachment circuits (ACs) to the GWs. Its functions are described in 218 [RFC4761][RFC4762][RFC6074] or [EVPN][PBB-EVPN]. 220 2.3. PW-based (Pseudowire-based) hand-off 222 If MPLS can be enabled between the GW and the WAN Edge router, a PW- 223 based Interconnect solution can be deployed. In this option the 224 hand-off between both routers is based on FEC128-based PWs or FEC129- 225 based PWs (for a greater level of network automation). Note that this 226 model still provides a clear demarcation boundary between DC and WAN, 227 and security/QoS policies may be applied on a per PW basis. This 228 model provides better scalability than a C-TAG based hand-off and 229 less provisioning overhead than a combined C/S-TAG hand-off. The 230 PW-based hand-off interconnect is illustrated in Figure 1 (between 231 the NVO-2 GWs and the WAN Edge routers). 233 In this model, besides the usual MPLS procedures between GW and WAN 234 Edge router, the GW MUST support an interworking function in each 235 MAC-VRF that requires extension to the WAN: 237 o If a FEC128-based PW is used between the MAC-VRF (GW) and the VSI 238 (WAN Edge), the provisioning of the VCID for such PW MUST be 239 supported on the MAC-VRF and must match the VCID used in the peer 240 VSI at the WAN Edge router. 242 o If BGP Auto-discovery [RFC6074] and FEC129-based PWs are used 243 between the GW MAC-VRF and the WAN Edge VSI, the provisioning of 244 the VPLS-ID MUST be supported on the MAC-VRF and must match the 245 VPLS-ID used in the WAN Edge VSI. 247 2.4. Multi-homing solution on the GWs 249 As already discussed, single-active multi-homing, i.e. per-service 250 load-balancing multi-homing MUST be supported in this type of 251 interconnect. All-active multi-homing may be considered in future 252 revisions of this document. 254 The GWs will be provisioned with a unique ESI per WAN interconnect 255 and the hand-off attachment circuits or PWs between the GW and the 256 WAN Edge router will be assigned to such ESI. The ESI will be 257 administratively configured on the GWs according to the procedures in 258 [EVPN]. This Interconnect ESI will be referred as "I-ESI" hereafter. 260 The solution (on the GWs) MUST follow the single-active multi-homing 261 procedures as described in [EVPN-Overlays] for the provisioned I-ESI, 262 i.e. Ethernet A-D routes per ESI and per EVI will be advertised to 263 the DC NVEs. The MAC addresses learnt (in the data plane) on the 264 hand-off links will be advertised with the I-ESI encoded in the ESI 265 field. 267 2.5. Gateway Optimizations 269 The following features MAY be supported on the GW in order to 270 optimize the control plane and data plane in the DC. 272 2.5.1 Use of the Unknown MAC route to reduce unknown flooding 274 The use of EVPN in the NVO networks brings a significant number of 275 benefits as described in [EVPN-Overlays]. There are however some 276 potential issues that SHOULD be addressed when the DC EVIs are 277 connected to the WAN VPN instances. 279 The first issue is the additional unknown unicast flooding created in 280 the DC due to the unknown MACs existing beyond the GW. In virtualized 281 DCs where all the MAC addresses are learnt in the control/management 282 plane, unknown unicast flooding is significantly reduced. This is no 283 longer true if the GW is connected to a layer-2 domain with data 284 plane learning. 286 The solution suggested in this document is based on the use of an 287 "Unknown MAC route" that is advertised by the Designated Forwarder 288 GW. The Unknown MAC route is a regular EVPN MAC/IP Advertisement 289 route where the MAC Address Length is set to 48 and the MAC address 290 to 00:00:00:00:00:00 (IP length is set to 0). 292 If this procedure is used, when an EVI is created in the GWs and the 293 Designated Forwarder (DF) is elected, the DF will send the Unknown 294 MAC route. The NVEs supporting this concept will prune their unknown 295 unicast flooding list and will only send the unknown unicast packets 296 to the owner of the Unknown MAC route. Note that the I-ESI will be 297 encoded in the ESI field of the NLRI so that regular multi-homing 298 procedures can be applied to this unknown MAC too (e.g. backup-path). 300 2.5.2. MAC address advertisement control 302 Another issue derived from the EVI interconnect to the WAN layer-2 303 domain is the potential massive MAC advertisement into the DC. All 304 the MAC addresses learnt from the WAN on the hand-off attachment 305 circuits or PWs must be advertised by BGP EVPN. Even if optimized BGP 306 techniques like RT-constraint are used, the amount of MAC addresses 307 to advertise or withdraw (in case of failure) from the GWs can be 308 difficult to control and overwhelming for the DC network, especially 309 when the NVEs reside in the hypervisors. 311 This document proposes the addition of administrative options so that 312 the user can enable/disable the advertisement of MAC addresses learnt 313 from the WAN as well as the advertisement of the Unknown MAC route 314 from the DF GW. In cases where all the DC MAC addresses are learnt in 315 the control/management plane, the GW may disable the advertisement of 316 WAN MAC addresses. Any frame with unknown destination MAC will be 317 exclusively sent to the Unknown MAC route owner(s). 319 2.5.3. ARP flooding control 321 Another optimization mechanism, naturally provided by EVPN in the 322 GWs, is the Proxy ARP/ND function. The GWs SHOULD build a Proxy 323 ARP/ND cache table as per [EVPN]. When the active GW receives an 324 ARP/ND request/solicitation coming from the WAN, the GW does a Proxy 325 ARP/ND table lookup and replies as long as the information is 326 available in its table. 328 This mechanism is especially recommended on the GWs since it protects 329 the DC network from external ARP/ND-flooding storms. 331 2.5.4. Handling failures between GW and WAN Edge routers 333 Link/PE failures MUST be handled on the GWs as specified in [EVPN]. 335 The GW detecting the failure will withdraw the EVPN routes as per 336 [EVPN]. 338 Individual AC/PW failures should be detected by OAM mechanisms. For 339 instance: 341 o If the Interconnect solution is based on a VLAN hand-off, 342 802.1ag/Y.1731 Ethernet-CFM MAY be used to detect individual AC 343 failures on both, the GW and WAN Edge router. An individual AC 344 failure will trigger the withdrawal of the corresponding A-D per 345 EVI route as well as the MACs learnt on that AC. 347 o If the Interconnect solution is based on a PW hand-off, the LDP PW 348 Status bits TLV MAY be used to detect individual PW failures on 349 both, the GW and WAN Edge router. 351 3. Integrated Interconnect solution for EVPN overlay networks 353 When the DC and the WAN are operated by the same administrative 354 entity, the Service Provider can decide to integrate the GW and WAN 355 Edge PE functions in the same router for obvious CAPEX and OPEX 356 saving reasons. This is illustrated in Figure 2. Note that this model 357 does not provide an explicit demarcation link between DC and WAN 358 anymore. 360 +--+ 361 |CE| 362 +--+ 363 | 364 +----+ 365 +----| PE |----+ 366 +---------+ | +----+ | +---------+ 367 +----+ | +---+ +---+ | +----+ 368 |NVE1|--| | | | | |--|NVE3| 369 +----+ | |GW1| |GW3| | +----+ 370 | +---+ +---+ | 371 | NVO-1 | WAN | NVO-2 | 372 | +---+ +---+ | 373 | | | | | | 374 +----+ | |GW2| |GW4| | +----+ 375 |NVE2|--| +---+ +---+ |--|NVE4| 376 +----+ +---------+ | | +---------+ +----+ 377 +--------------+ 379 |<--EVPN-Overlay--->|<-----VPLS--->|<---EVPN-Overlay-->| 380 |<--PBB-VPLS-->| 381 Interconnect -> |<-EVPN-MPLS-->| 382 options |<--EVPN-Ovl-->| 383 |<--PBB-EVPN-->| 385 Figure 2 Integrated Interconnect model 387 3.1. Interconnect requirements 389 The solution must observe the following requirements: 391 o The GW function must provide control plane and data plane 392 interworking between the EVPN-overlay network and the L2VPN 393 technology supported in the WAN, i.e. (PBB-)VPLS or (PBB-)EVPN, as 394 depicted in Figure 2. 396 o Multi-homing MUST be supported. Single-active multi-homing with 397 per-service load balancing MUST be implemented. All-active multi- 398 homing, i.e. per-flow load-balancing, MUST be implemented as long 399 as the technology deployed in the WAN supports it. 401 o If EVPN is deployed in the WAN, the MAC Mobility, Static MAC 402 protection and other procedures (e.g. proxy-arp) described in 403 [EVPN] must be supported end-to-end. 405 o Any type of inclusive multicast tree MUST be independently 406 supported in the WAN as per [EVPN], and in the DC as per [EVPN- 407 Overlays]. 409 3.2. VPLS Interconnect for EVPN-Overlay networks 411 3.2.1. Control/Data Plane setup procedures on the GWs 413 Regular MPLS tunnels and TLDP/BGP sessions will be setup to the WAN 414 PEs and RRs as per [RFC4761][RFC4762][RFC6074] and overlay tunnels 415 and EVPN will be setup as per [EVPN-Overlays]. Note that different 416 route-targets for the DC and for the WAN are normally required. A 417 single type-1 RD per service can be used. 419 In order to support multi-homing, the GWs will be provisioned with an 420 I-ESI (see section 2.4), that will be unique per interconnection. All 421 the [EVPN] procedures are still followed for the I-ESI, e.g. any MAC 422 address learnt from the WAN will be advertised to the DC with the 423 I-ESI in the ESI field. 425 A MAC-VRF per EVI will be created in each GW. The MAC-VRF will have 426 two different types of tunnel bindings instantiated in two different 427 split-horizon-groups: 429 o VPLS PWs will be instantiated in the "WAN split-horizon-group". 431 o Overlay tunnel bindings (e.g. VXLAN, NVGRE) will be instantiated 432 in the "DC split-horizon-group". 434 Attachment circuits are also supported on the same MAC-VRF, but they 435 will not be part of any of the above split-horizon-groups. 437 Traffic received in a given split-horizon-group will never be 438 forwarded to a member of the same split-horizon-group. 440 As far as BUM flooding is concerned, a flooding list will be created 441 with the sub-list created by the inclusive multicast routes and the 442 sub-list created for VPLS in the WAN. BUM frames received from a 443 local attachment circuit will be flooded to both sub-lists. BUM 444 frames received from the DC or the WAN will be forwarded to the 445 flooding list observing the split-horizon-group rule described above. 447 Note that the GWs are not allowed to have an EVPN binding and a PW to 448 the same far-end within the same MAC-VRF in order to avoid loops and 449 packet duplication. This is described in [EVPN-VPLS-INTEGRATION]. 451 The optimizations procedures described in section 2.5 can also be 452 applied to this model. 454 3.2.2. Multi-homing procedures on the GWs 455 Single-active multi-homing MUST be supported on the GWs. All-active 456 multi-homing is not supported by VPLS. 458 All the single-active multi-homing procedures as described by [EVPN- 459 Overlays] will be followed for the I-ESI. 461 The non-DF GW for the I-ESI will block the transmission and reception 462 of all the bindings in the "WAN split-horizon-group" for BUM and 463 unicast traffic. 465 3.3. PBB-VPLS Interconnect for EVPN-Overlay networks 467 3.3.1. Control/Data Plane setup procedures on the GWs 469 In this case, there is no impact on the procedures described in 470 [RFC7041] for the B-component. However the I-component instances 471 become EVI instances with EVPN-Overlay bindings and potentially local 472 attachment circuits. M MAC-VRF instances can be multiplexed into the 473 same B-component instance. This option provides significant savings 474 in terms of PWs to be maintained in the WAN. 476 The I-ESI concept described in section 3.2.1 will also be used for 477 the PBB-VPLS-based Interconnect. 479 B-component PWs and I-component EVPN-overlay bindings established to 480 the same far-end will be compared. The following rules will be 481 observed: 483 o Attempts to setup a PW between the two GWs within the B- 484 component context will never be blocked. 486 o If a PW exists between two GWs for the B-component and an 487 attempt is made to setup an EVPN binding on an I-component linked 488 to that B-component, the EVPN binding will be kept operationally 489 down. Note that the BGP EVPN routes will still be valid but not 490 used. 492 o The EVPN binding will only be up and used as long as there is no 493 PW to the same far-end in the corresponding B-component. The EVPN 494 bindings in the I-components will be brought down before the PW in 495 the B-component is brought up. 497 The optimizations procedures described in section 2.5 can also be 498 applied to this Interconnect option. 500 3.3.2. Multi-homing procedures on the GWs 502 Single-active multi-homing MUST be supported on the GWs. 504 All the single-active multi-homing procedures as described by [EVPN- 505 Overlays] will be followed for the I-ESI for each EVI instance 506 connected to B-component. 508 3.4. EVPN-MPLS Interconnect for EVPN-Overlay networks 510 If EVPN for MPLS tunnels, EVPN-MPLS hereafter, is supported in the 511 WAN, an end-to-end EVPN solution can be deployed. The following 512 sections describe the proposed solution as well as the impact 513 required on the [EVPN] procedures. 515 3.4.1. Control Plane setup procedures on the GWs 517 The GWs MUST establish separate BGP sessions for sending/receiving 518 EVPN routes to/from the DC and to/from the WAN. Normally each GW will 519 setup one (two) BGP EVPN session(s) to the DC RR(s) and one(two) 520 session(s) to the WAN RR(s). The same route-distinguisher (RD) per 521 MAC-VRF can be used for the EVPN routes sent to both, WAN and DC RRs. 522 On the contrary, although reusing the same value is possible, 523 different route-targets are expected to be handled for the same EVI 524 in the WAN and the DC. 526 As in the other discussed options, an I-ESI will be configured on the 527 GWs for multi-homing. 529 Received EVPN routes will never be reflected on the GWs but consumed 530 and re-advertised (if needed): 532 o Ethernet A-D routes, ES routes and inclusive multicast routes 533 are consumed by the GWs and processed locally for the 534 corresponding [EVPN] procedures. 536 o MAC/IP advertisement routes will be received, imported and if 537 they become active in the MAC-VRF MAC FIB, the information will 538 be re-advertised as new routes with the following fields: 540 + The RD will be the GW's RD for the MAC-VRF. 542 + The ESI will be set to the I-ESI. 544 + The Ethernet-tag will be 0 or a new value. 546 + The MAC length, MAC address, IP Length and IP address values 547 will be kept from the received DC NLRI. 549 + The MPLS label will be a local value (when sent to the WAN) or 550 a DC-global value (when sent to the DC). 552 + The appropriate Route-Targets (RTs) and [RFC5512] BGP 553 Encapsulation extended community will be used according to 554 [EVPN-Overlays]. 556 The GWs will also generate the following local EVPN routes that will 557 be sent to the DC and WAN, with their corresponding RTs and [RFC5512] 558 BGP Encapsulation extended community values: 560 o ES route for the I-ESI. 562 o Ethernet A-D routes per ESI and EVI for the I-ESI. 564 o Inclusive multicast routes with independent tunnel type value 565 for the WAN and DC. E.g. a P2MP LSP may be used in the WAN 566 whereas ingress replication is used in the DC. 568 o MAC/IP advertisement routes for MAC addresses learnt in local 569 attachment circuits. Note that these routes will not include the 570 I-ESI, but ESI=0 or different from 0 for local Ethernet Segments 571 (ES). 573 Note that each GW will receive two copies of each of the above routes 574 generated by the peer GW (one copy for the DC encapsulation and one 575 copy for the WAN encapsulation). This is the expected behavior on the 576 GW: 578 o ES and A-D (per ESI) routes: regular BGP selection will be 579 applied. 581 o Inclusive multicast routes: if the Ethernet Tag ID matches on 582 both routes, regular BGP selection applies and only one route 583 will be active. It is recommended to influence the BGP selection 584 so that the DC route is preferred. If the Ethernet Tag ID does 585 not match, then BGP will consider them two separate routes. In 586 that case, the MAC-VRF will select the DC route. 588 o MAC/IP advertisement routes for local attachment circuits: as 589 above, the GW will select only one. The decision will be made at 590 BGP or MAC-RVRF level, depending on the Ethernet Tags. 592 The optimizations procedures described in section 2.5 can also be 593 applied to this option. 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 since only one EVPN binding will be setup in the data plane 600 between the two nodes. 602 As for the rest of the EVPN tunnel bindings, two flooding lists will 603 be setup by each GW for the same MAC-VRF: 605 o EVPN-overlay flooding list (composed of bindings to the remote 606 NVEs or multicast tunnel to the NVEs). 608 o EVPN-MPLS flooding list (composed of MP2P and or LSM tunnel to 609 the remote PEs) 611 Each flooding list will be part of a separate split-horizon-group. 612 Traffic generated from a local AC can be flooded to both 613 split-horizon-groups. Traffic from a binding of a split-horizon-group 614 can be flooded to the other split-horizon-group and local ACs, but 615 never to a member of its own split-horizon-group. 617 3.4.3. Multi-homing procedures on the GWs 619 Single-active as well as all-active multi-homing MUST be supported. 621 All the multi-homing procedures as described by [EVPN] will be 622 followed for the DF election for I-ESI, as well as the backup-path 623 (single-active) and aliasing (all-active) procedures on the remote 624 PEs/NVEs. The following changes are required at the GW with respect 625 to the I-ESI: 627 o Single-active multi-homing; assuming a WAN split-horizon-group, 628 a DC split-horizon-group and local ACs on the GWs: 630 + Forwarding behavior on the non-DF: the non-DF MUST NOT forward 631 BUM or unicast traffic received from a given split-horizon- 632 group to a member of his own split-horizon group or to the 633 other split-horizon-group. Only forwarding to local ACs is 634 allowed (as long as they are not part of an ES for which the 635 node is non-DF). 637 + Forwarding behavior on the DF: the DF MUST NOT forward BUM or 638 unicast traffic received from a given split-horizon-group to a 639 member of his own split-horizon group or to the non-DF. 640 Forwarding to the other split-horizon-group and local ACs is 641 allowed (as long as they are not part of an ES for which the 642 node is non-DF). 644 o All-active multi-homing; assuming a WAN split-horizon-group, a 645 DC split-horizon-group and local ACs on the GWs: 647 + Forwarding behavior on the non-DF: the non-DF follows the same 648 behavior as the non-DF in the single-active case but only for 649 BUM traffic. Unicast traffic received from a split-horizon- 650 group MUST NOT be forwarded to a member of its own split- 651 horizon-group but can be forwarded normally to the other 652 split-horizon-group and local ACs. If a known unicast packet 653 is identified as a "flooded" packet, the procedures for BUM 654 traffic MUST be followed. 656 + Forwarding behavior on the DF: the DF follows the same 657 behavior as the DF in the single-active case but only for BUM 658 traffic. Unicast traffic received from a split-horizon-group 659 MUST NOT be forwarded to a member of its own split-horizon- 660 group but can be forwarded normally to the other split- 661 horizon-group and local ACs. If a known unicast packet is 662 identified as a "flooded" packet, the procedures for BUM 663 traffic MUST be followed. 665 o No ESI label is required to be signaled for I-ESI for its use by 666 the non-DF in the data path. This is possible because the non-DF 667 and the DF will never forward BUM traffic (coming from a split- 668 horizon-group) to each other. 670 3.4.4. Impact on MAC Mobility procedures 672 Since the MAC/IP Advertisement routes are not reflected in the GWs 673 but rather consumed and re-advertised if active, the MAC Mobility 674 procedures can be constrained to each domain (DC or WAN) and resolved 675 within each domain. In other words, if a MAC moves within the DC, the 676 GW MUST NOT re-advertise the route to the WAN with a change in the 677 sequence number. Only when the MAC moves from the WAN domain to the 678 DC domain, the GW will re-advertise the MAC with a higher sequence 679 number in the MAC Mobility extended community. In respect to the MAC 680 Mobility procedures described in [EVPN] the MAC addresses learnt from 681 the NVEs in the local DC or on the local ACs will be considered as 682 local. 684 The sequence numbers MUST NOT be propagated between domains. The 685 sticky bit indication in the MAC Mobility extended community MUST be 686 propagated between domains. 688 3.4.5. Gateway optimizations 690 All the Gateway optimizations described in section 2.5 MAY be applied 691 to the GWs when the Interconnect is based on EVPN-MPLS. 693 In particular, the use of the Unknown MAC route, as described in 694 section 2.5.1, reduces the unknown flooding in the DC but also solves 695 some transient packet duplication issues in cases of all-active 696 multi-homing. This is explained in the following paragraph. 698 Consider the diagram in Figure 2 for EVPN-MPLS Interconnect and all- 699 active multi-homing, and the following sequence: 701 a) MAC Address M1 is advertised from NVE3 in EVI-1. 703 b) GW3 and GW4 learn M1 for EVI-1 and re-advertise M1 to the WAN 704 with I-ESI-2 in the ESI field. 706 c) GW1 and GW2 learn M1 and install GW3/GW4 as next-hops following 707 the EVPN aliasing procedures. 709 d) Before NVE1 learns M1, a packet arrives to NVE1 with 710 destination M1. The packet is subsequently flooded. 712 e) Since both GW1 and GW2 know M1, they both forward the packet to 713 the WAN (hence creating packet duplication), unless there is an 714 indication in the data plane that the packet from NVE1 has been 715 flooded. If the GWs signal the same VNI/VSID for MAC/IP 716 advertisement and inclusive multicast routes for EVI-1, such 717 data plane indication does not exist. 719 This undesired situation can be avoided by the use of the Unknown- 720 MAC-route. If this route is used, the NVEs will prune their unknown 721 unicast flooding list, and the non-DF GW will not received unknown 722 packets, only the DF will. This solves the MAC duplication issue 723 described above. 725 3.4.6. Benefits of the EVPN-MPLS Interconnect solution 727 Besides retaining the EVPN attributes between Data Centers and 728 throughout the WAN, the EVPN-MPLS Interconnect solution on the GWs 729 has some benefits compared to pure BGP EVPN RR or Inter-AS model B 730 solutions without a gateway: 732 o The solution supports the connectivity of local attachment 733 circuits on the GWs. 735 o Different data plane encapsulations can be supported in the DC 736 and the WAN. 738 o Optimized multicast solution, with independent inclusive 739 multicast trees in DC and WAN. 741 o MPLS Label aggregation: for the case where MPLS labels are 742 signaled from the NVEs for MAC/IP Advertisement routes, this 743 solution provides label aggregation. A remote PE MAY receive a 744 single label per GW MAC-VRF as opposed to a label per NVE/MAC- 745 VRF connected to the GW MAC-VRF. For instance, in Figure 2, PE 746 would receive only one label for all the routes advertised for a 747 given MAC-VRF from GW1, as opposed to a label per NVE/MAC-VRF. 749 o The GW will not propagate MAC mobility for the MACs moving 750 within a DC. Mobility intra-DC is solved by all the NVEs in the 751 DC. The MAC Mobility procedures on the GWs are only required in 752 case of mobility across DCs. 754 o Proxy-ARP/ND function on the DGWs can be leveraged to reduce 755 ARP/ND flooding in the DC or/and in the WAN. 757 3.5. PBB-EVPN Interconnect for EVPN-Overlay networks 759 [PBB-EVPN] is yet another Interconnect option. It requires the use of 760 GWs where I-components and associated B-components are EVI 761 instances. 763 3.5.1. Control/Data Plane setup procedures on the GWs 765 EVPN will run independently in both components, the I-component MAC- 766 VRF and B-component MAC-VRF. Compared to [PBB-EVPN], the DC C-MACs 767 are no longer learnt in the data plane on the GW but in the control 768 plane through EVPN running on the I-component. Remote C-MACs coming 769 from remote PEs are still learnt in the data plane. B-MACs in the B- 770 component will be assigned and advertised following the procedures 771 described in [PBB-EVPN]. 773 An I-ESI will be configured on the GWs for multi-homing, but it will 774 only be used in the EVPN control plane for the I-component EVI. No 775 non-reserved ESIs will be used in the control plane of the B- 776 component EVI as per [PBB-EVPN]. 778 The rest of the control plane procedures will follow [EVPN] for the 779 I-component EVI and [PBB-EVPN] for the B-component EVI. 781 From the data plane perspective, the I-component and B-component EVPN 782 bindings established to the same far-end will be compared and the I- 783 component EVPN-overlay binding will be kept down following the rules 784 described in section 3.3.1. 786 3.5.2. Multi-homing procedures on the GWs 788 Single-active as well as all-active multi-homing MUST be supported. 790 The forwarding behavior of the DF and non-DF will be changed based on 791 the description outlined in section 3.4.3, only replacing the "WAN 792 split-horizon-group" for the B-component. 794 3.5.3. Impact on MAC Mobility procedures 796 C-MACs learnt from the B-component will be advertised in EVPN within 797 the I-component EVI scope. If the C-MAC was previously known in the 798 I-component database, EVPN would advertise the C-MAC with a higher 799 sequence number, as per [EVPN]. From a Mobility perspective and the 800 related procedures described in [EVPN], the C-MACs learnt from the B- 801 component are considered local. 803 3.5.4. Gateway optimizations 805 All the considerations explained in section 3.4.5 are applicable to 806 the PBB-EVPN Interconnect option. 808 3.6. EVPN-VXLAN Interconnect for EVPN-Overlay networks 810 If EVPN for Overlay tunnels is supported in the WAN and a GW function 811 is required, an end-to-end EVPN solution can be deployed. This 812 section focuses on the specific case of EVPN for VXLAN (EVPN-VXLAN 813 hereafter) and the impact on the [EVPN] procedures. 815 This use-case assumes that NVEs need to use the VNIs or VSIDs as a 816 globally unique identifiers within a data center, and a Gateway needs 817 to be employed at the edge of the data center network to translate 818 the VNI or VSID when crossing the network boundaries. This GW 819 function provides VNI and tunnel IP address translation. The use-case 820 in which local downstream assigned VNIs or VSIDs can be used (like 821 MPLS labels) is described by [EVPN-Overlays]. 823 While VNIs are globally significant within each DC, there are two 824 possibilities in the Interconnect network: 826 a) Globally unique VNIs in the Interconnect network: 827 In this case, the GWs and PEs in the Interconnect network will 828 agree on a common VNI for a given EVI. The RT to be used in the 829 Interconnect network can be auto-derived from the agreed 830 Interconnect VNI. The VNI used inside each DC MAY be the same 831 as the Interconnect VNI. 833 b) Downstream assigned VNIs in the Interconnect network. 834 In this case, the GWs and PEs MUST use the proper RTs to 835 import/export the EVPN routes. Note that even if the VNI is 836 downstream assigned in the Interconnect network, and unlike 837 option B, it only identifies the pair and 838 not the pair. The VNI used inside 839 each DC MAY be the same as the Interconnect VNI. GWs SHOULD 840 support multiple VNI spaces per EVI (one per Interconnect 841 network they are connected to). 843 In both options, NVEs inside a DC only have to be aware of a single 844 VNI space, and only GWs will handle the complexity of managing 845 multiple VNI spaces. In addition to VNI translation above, the GWs 846 will provide translation of the tunnel source IP for the packets 847 generated from the NVEs, using their own IP address. GWs will use 848 that IP address as the BGP next-hop in all the EVPN updates to the 849 Interconnect network. 851 The following sections provide more details about these two options. 853 3.6.1. Globally unique VNIs in the Interconnect network 855 Considering Figure 2, if a host H1 in NVO-1 needs to communicate with 856 a host H2 in NVO-2, and assuming that different VNIs are used in each 857 DC for the same EVI, e.g. VNI-10 in NVO-1 and VNI-20 in NVO-2, then 858 the VNIs must be translated to a common Interconnect VNI (e.g. VNI- 859 100) on the GWs. Each GW is provisioned with a VNI translation 860 mapping so that it can translate the VNI in the control plane when 861 sending BGP EVPN route updates to the Interconnect network. In other 862 words, GW1 and GW2 must be configured to map VNI-10 to VNI-100 in the 863 BGP update messages for H1's MAC route. This mapping is also used to 864 translate the VNI in the data plane in both directions, that is, VNI- 865 10 to VNI-100 when the packet is received from NVO-1 and the reverse 866 mapping from VNI-100 to VNI-10 when the packet is received from the 867 remote NVO-2 network and needs to be forwarded to NVO-1. 869 The procedures described in section 3.4 will be followed, considering 870 that the VNIs advertised/received by the GWs will be translated 871 accordingly. 873 3.6.2. Downstream assigned VNIs in the Interconnect network 875 In this case, if a host H1 in NVO-1 needs to communicate with a host 876 H2 in NVO-2, and assuming that different VNIs are used in each DC for 877 the same EVI, e.g. VNI-10 in NVO-1 and VNI-20 in NVO-2, then the VNIs 878 must be translated as in section 3.6.1. However, in this case, there 879 is no need to translate to a common Interconnect VNI on the GWs. Each 880 GW can translate the VNI received in an EVPN update to a locally 881 assigned VNI advertised to the Interconnect network. Each GW can use 882 a different Interconnect VNI, hence this VNI does not need to be 883 agreed on all the GWs and PEs of the Interconnect network. 885 The procedures described in section 3.4 will be followed, taking the 886 considerations above for the VNI translation. 888 5. Conventions and Terminology 890 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 891 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 892 document are to be interpreted as described in RFC-2119 [RFC2119]. 894 AC: Attachment Circuit 896 BUM: it refers to the Broadcast, Unknown unicast and Multicast 897 traffic 899 DF: Designated Forwarder 901 GW: Gateway or Data Center Gateway 903 DCI: Data Center Interconnect 905 ES: Ethernet Segment 907 ESI: Ethernet Segment Identifier 909 I-ESI: Interconnect ESI defined on the GWs for multi-homing to/from 910 the WAN 912 EVI: EVPN Instance 914 MAC-VRF: it refers to an EVI instance in a particular node 916 NVE: Network Virtualization Edge 918 PW: Pseudowire 920 RD: Route-Distinguisher 922 RT: Route-Target 924 TOR: Top-Of-Rack switch 926 VNI/VSID: refers to VXLAN/NVGRE virtual identifiers 928 VSI: Virtual Switch Instance or VPLS instance in a particular PE 930 6. Security Considerations 932 This section will be completed in future versions. 934 7. IANA Considerations 935 8. References 937 8.1. Normative References 939 [RFC4761]Kompella, K., Ed., and Y. Rekhter, Ed., "Virtual Private LAN 940 Service (VPLS) Using BGP for Auto-Discovery and Signaling", RFC 4761, 941 January 2007, . 943 [RFC4762]Lasserre, M., Ed., and V. Kompella, Ed., "Virtual Private 944 LAN Service (VPLS) Using Label Distribution Protocol (LDP) 945 Signaling", RFC 4762, January 2007, . 948 [RFC6074]Rosen, E., Davie, B., Radoaca, V., and W. Luo, 949 "Provisioning, Auto-Discovery, and Signaling in Layer 2 Virtual 950 Private Networks (L2VPNs)", RFC 6074, January 2011, . 953 [RFC7041]Balus, F., Ed., Sajassi, A., Ed., and N. Bitar, Ed., 954 "Extensions to the Virtual Private LAN Service (VPLS) Provider Edge 955 (PE) Model for Provider Backbone Bridging", RFC 7041, November 2013, 956 . 958 8.2. Informative References 960 [EVPN] Sajassi et al., "BGP MPLS Based Ethernet VPN", draft-ietf- 961 l2vpn-evpn-11.txt, work in progress, October, 2014 963 [PBB-EVPN] Sajassi et al., "PBB-EVPN", draft-ietf-l2vpn-pbb-evpn-07, 964 work in progress, June, 2014 966 [EVPN-Overlays] Sajassi-Drake et al., "A Network Virtualization 967 Overlay Solution using EVPN", draft-ietf-bess-evpn-overlay-00.txt, 968 work in progress, November, 2014 970 [EVPN-VPLS-INTEGRATION] Sajassi et al., "(PBB-)EVPN Seamless 971 Integration with (PBB-)VPLS", draft-sajassi-bess-evpn-vpls- 972 integration-00.txt, work in progress, October, 2014 974 9. Acknowledgments 976 This document was prepared using 2-Word-v2.0.template.dot. 978 10. Authors' Addresses 979 Jorge Rabadan 980 Alcatel-Lucent 981 777 E. Middlefield Road 982 Mountain View, CA 94043 USA 983 Email: jorge.rabadan@alcatel-lucent.com 985 Senthil Sathappan 986 Alcatel-Lucent 987 Email: senthil.sathappan@alcatel-lucent.com 989 Wim Henderickx 990 Alcatel-Lucent 991 Email: wim.henderickx@alcatel-lucent.com 993 Florin Balus 994 Nuage Networks 995 Email: florin@nuagenetworks.net 997 Senad Palislamovic 998 Alcatel-Lucent 999 Email: senad.palislamovic@alcatel-lucent.com 1001 Ali Sajassi 1002 Cisco 1003 Email: sajassi@cisco.com 1005 Ravi Shekhar 1006 Juniper 1007 Email: rshekhar@juniper.net 1009 Anil Lohiya 1010 Juniper 1011 Email: alohiya@juniper.net 1013 Dennis Cai 1014 Cisco Systems 1015 Email: dcai@cisco.com