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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Inter-Domain Routing 3 Internet-Draft 4 Intended status: Standards Track G. Dawra, Ed. 5 Expires: April 19, 2018 C. Filsfils 6 D. Dukes 7 P. Brissette 8 P. Camarilo 9 Cisco Systems 10 J. Leddy 11 Comcast 12 D. Voyer 13 D. Bernier 14 Bell Canada 15 D. Steinberg 16 Steinberg Consulting 17 R. Raszuk 18 Bloomberg LP 19 B. Decraene 20 Orange 21 S. Matsushima 22 SoftBank 23 October 16, 2017 25 BGP Signaling of IPv6-Segment-Routing-based VPN Networks 26 draft-dawra-idr-srv6-vpn-02.txt 28 Abstract 30 This draft defines procedures and messages for BGP SRv6-based L3VPN 31 and EVPN. It builds on RFC4364 "BGP/MPLS IP Virtual Private Networks 32 (VPNs)" and "RFC7432 "BGP MPLS-Based Ethernet VPN" and provides a 33 migration path from MPLS-based VPNs to SRv6 based VPNs. 35 Status of This Memo 37 This Internet-Draft is submitted in full conformance with the 38 provisions of BCP 78 and BCP 79. 40 Internet-Drafts are working documents of the Internet Engineering 41 Task Force (IETF). Note that other groups may also distribute 42 working documents as Internet-Drafts. The list of current Internet- 43 Drafts is at https://datatracker.ietf.org/drafts/current/. 45 Internet-Drafts are draft documents valid for a maximum of six months 46 and may be updated, replaced, or obsoleted by other documents at any 47 time. It is inappropriate to use Internet-Drafts as reference 48 material or to cite them other than as "work in progress." 49 This Internet-Draft will expire on April 19, 2018. 51 Copyright Notice 53 Copyright (c) 2017 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 (https://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. SRv6-VPN SID TLV . . . . . . . . . . . . . . . . . . . . . . 3 70 3. BGP based L3 over SRv6 . . . . . . . . . . . . . . . . . . . 5 71 3.1. IPv4 VPN Over SRv6 Core . . . . . . . . . . . . . . . . . 6 72 3.2. IPv6 VPN Over SRv6 Core . . . . . . . . . . . . . . . . . 6 73 3.3. Global IPv4 over SRv6 Core . . . . . . . . . . . . . . . 7 74 3.4. Global IPv6 over SRv6 Core . . . . . . . . . . . . . . . 7 75 4. BGP based Ethernet VPN(EVPN) over SRv6 . . . . . . . . . . . 8 76 4.1. Ethernet Auto-discovery Route over SRv6 Core . . . . . . 8 77 4.1.1. EVPN Route Type-1(Per ES AD) . . . . . . . . . . . . 9 78 4.1.2. Prefix Type-1(Per EVI/ES AD) . . . . . . . . . . . . 9 79 4.2. MAC/IP Advertisement Route(Type-2) with SRv6 Core . . . . 10 80 4.3. Inclusive Multicast Ethernet Tag Route with SRv6 Core . . 11 81 4.4. Ethernet Segment Route with SRv6 Core . . . . . . . . . . 13 82 4.5. IP prefix router(Type-5) with SRv6 Core . . . . . . . . . 13 83 4.6. Multicast routes (EVPN Route Type-6, Type-7, Type-8) . . 14 84 5. Migration from L3 MPLS based Segment Routing to SRv6 Segment 85 Routing . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 86 6. Implementation Status . . . . . . . . . . . . . . . . . . . . 15 87 7. Error Handling of BGP SRv6 SID Updates . . . . . . . . . . . 15 88 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 89 9. Security Considerations . . . . . . . . . . . . . . . . . . . 15 90 10. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . 15 91 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 15 92 11.1. Normative References . . . . . . . . . . . . . . . . . . 16 93 11.2. Informative References . . . . . . . . . . . . . . . . . 17 94 11.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 18 95 Appendix A. Contributors . . . . . . . . . . . . . . . . . . . . 18 96 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18 98 1. Introduction 100 SRv6 refers to Segment Routing instantiated on the IPv6 dataplane [I- 101 D.filsfils-spring-srv6-network-programming][I-D.ietf-6man-segment-rou 102 ting-header]. 104 SRv6-based VPN (SRv6-VPN) refers to the creation of VPN between PE's 105 leveraging the SRv6 dataplane and more specifically the END.DT* 106 (crossconnect to a VRF) and END.DX* (crossconnect to a nexthop). 107 SRv6-L3VPN refers to the creation of Layer3 VPN service between PE's 108 supporting an SRv6 data plane. SRv6-EVPN refers to the creation of 109 Layer2/Layer3 VPN service between PE's supporting an SRv6 data plane. 111 SRv6 SID refers to a SRv6 Segment Identifier as defined in 112 [I-D.filsfils-spring-srv6-network-programming]. 114 SRv6-VPN SID refers to an SRv6 SID that MAY be associated with one of 115 the END.DT or END.DX functions as defined in 116 [I-D.filsfils-spring-srv6-network-programming]. 118 To provide SRv6-VPN service with best-effort connectivity, the egress 119 PE signals an SRv6-VPN SID with the VPN route. The ingress PE 120 encapsulates the VPN packet in an outer IPv6 header where the 121 destination address is the SRv6-VPN SID provided by the egress PE. 122 The underlay between the PE's only need to support plain IPv6 123 forwarding [RFC2460]. 125 To provide SRv6-VPN service in conjunction with an underlay SLA from 126 the ingress PE to the egress PE, the egress PE colors the overlay VPN 127 route with a color extended community. The ingress PE encapsulates 128 the VPN packet in an outer IPv6 header with an SRH that contains the 129 SR policy associated with the related SLA followed by the SRv6-VPN 130 SID associated with the route. The underlay nodes whose SRv6 SID's 131 are part of the SRH must support SRv6 data plane. 133 BGP is used to advertise the reachability of prefixes in a particular 134 VPN from an egress Provider Edge (egress-PE) to ingress Provider Edge 135 (ingress-PE) nodes. 137 This document describes how existing BGP messages between PEs may 138 carry SRv6 Segment IDs (SIDs) as a means to interconnect PEs and form 139 VPNs. 141 2. SRv6-VPN SID TLV 143 The SRv6-VPN SID TLV is defined as another TLV for BGP-Prefix-SID 144 Attribute [I-D.ietf-idr-bgp-prefix-sid]. The value field of the BGP 145 Prefix SID attribute is defined here to be a set of elements encoded 146 as "Type/Length/Value" (i.e., a set of TLVs). Type for SRv6-VPN SID 147 TLV is defined to be TBD. 149 The IPv6-SID TLV MUST be present in the Prefix-SID attribute attached 150 to MP-BGP VPN NLRI defined in [RFC4659][RFC5549][RFC7432] when 151 egress-PE is capable of SRv6 data-plane. 153 0 1 2 3 154 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 155 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 156 | Type | Length | RESERVED | 157 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 158 | SRv6 SID information(Variable) | 159 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 161 SRv6 SID information is encoded as follows: 163 +---------------------------------------+ 164 | SID Type (1 Octet) | 165 +---------------------------------------+ 166 | SRv6 SID (16 octet) | 167 +---------------------------------------+ 169 Where: 171 o Type is TBD 173 o Length: 16bit field. The total length of the value portion of the 174 TLV. 176 o RESERVED: 8 bit field. SHOULD be 0 on transmission and MUST be 177 ignored on reception. 179 Current Type of SID defined as: 181 o Type-1 - corresponds to the equivalent functionality provided by a 182 VPN MPLS Label attribute when received with a route containing a 183 MPLS label[RFC4364]. Some functions which MAY be encoded are 184 End.DX4, End.DT4, End.DX6, End.DT6 etc. 186 o Type-2 - corresponds to the equivalent functionality provided by a 187 MPLS Label1 when received with a EVPN Route Type-2 defined 188 in[RFC7432]. Some functions which MAY be encoded are End.DX2, 189 End.DX2V, End.DT2U, End.DT2M / Arg.FE2 etc. 191 3. BGP based L3 over SRv6 193 BGP egress nodes (egress-PEs) advertise a set of reachable prefixes. 194 Standard BGP update propagation schemes [RFC4271], which MAY make use 195 of route reflectors [RFC4456], are used to propagate these prefixes. 196 BGP ingress nodes (ingress-PE) receive these advertisements and may 197 add the prefix to the RIB in an appropriate VRF. 199 For egress-PEs which supports SRv6-VPN advertises an SRv6-VPN SID 200 with VPN routes. This SRv6-VPN SID only has local significance at 201 the egress-PE where it is allocated or configured on a per-CE or per- 202 VRF basis. In practice, the SID encodes a cross-connect to a 203 specific Address Family table (END.DT) or next-hop/interface (END.DX) 204 as defined in the SRv6 Network Programming Document 205 [I-D.filsfils-spring-srv6-network-programming] 207 The SRv6 VPN SID MAY be routable within the AS of the egress-PE and 208 serves the dual purpose of providing reachability between ingress-PE 209 and egress-PE while also encoding the VPN identifier. 211 To support SRv6 based L3VPN overlay, a SID is advertised with BGP 212 MPLS L3VPN route update[RFC4364]. SID is encoded in a SRv6-VPN SID 213 TLV, which is optional transitive BGP Prefix SID 214 attribute[I-D.ietf-idr-bgp-prefix-sid]. This attribute serves two 215 purposes; first it indicates that the BGP egress device is reachable 216 via an SRv6 underlay and the BGP ingress device receiving this route 217 MAY choose to encapsulate or insert an SRv6 SRH, second it indicates 218 the value of the SID to include in the SRH encapsulation. For L3VPN, 219 only a single SRv6-VPN SID MAY be necessary. A BGP speaker 220 supporting an SRv6 underlay MAY distribute SID per route via the BGP 221 SRv6-VPN Attribute. If the BGP speaker supports MPLS based L3VPN 222 simultaneously, it MAY also populate the Label values in L3VPN route 223 types and allow the BGP ingress device to decide which encapsulation 224 to use. If the BGP speaker does not support MPLS based L3VPN 225 services the MPLS Labels in L3VPN route types MUST be set to 226 IMPLICIT-NULL. Similarly, to support SRv6 based EVPN a SID (or 227 multiple SIDs) are advertised in route-types 1, 2, 3 and 5[RFC7432] 229 At an ingress-PE, BGP installs the advertised prefix in the correct 230 RIB table, recursive via an SR Policy leveraging the received 231 SRv6-VPN SID. 233 Assuming best-effort connectivity to the egress PE, the SR policy has 234 a path with a SID list made up of a single SID: the SRv6-VPN SID 235 received with the related BGP route update. 237 When the VPN route is colored with an extended color community C and 238 the SID is next-hop N and the ingress PE has a valid SRv6 Policy (N, 239 C) associated with SID list 240 [I-D.filsfils-spring-segment-routing-policy] then the SR Policy is 241 . 243 Multiple VPN routes MAY resolve recursively on the same SR Policy. 245 3.1. IPv4 VPN Over SRv6 Core 247 IPv4 VPN Over IPv6 Core is defined in [RFC5549], the MP_REACH_NLRI is 248 encoded as follows for an SRv6 Core: 250 o AFI = 1 252 o SAFI = 128 254 o Length of Next Hop Network Address = 16 (or 32) 256 o Network Address of Next Hop = IPv6 address of the egress PE 258 o NLRI = IPv4-VPN routes 260 o Label = Implicit-Null 262 SRv6-VPN SID is encoded as part of the SRv6-VPN SID TLV defined in 263 Section 2. The function of the SRv6 SID is entirely up to the 264 originator of the advertisement. In practice, the function may 265 likely be End.DX4 or End.DT4. 267 3.2. IPv6 VPN Over SRv6 Core 269 IPv6 VPN over IPv6 Core is defined in [RFC4659], the MP_REACH_NLRI is 270 enclosed as follows for an SRv6 Core: 272 o AFI = 2 274 o SAFI = 128 276 o Length of Next Hop Network Address = 16 (or 32) 278 o Network Address of Next Hop = IPv6 address of the egress PE 280 o NLRI = IPv6-VPN routes 282 o Label = Implicit-Null 284 SRv6-VPN SID are encoded as part of the SRv6-VPN SID TLV defined in 285 Section 2. The function of the IPv6 SRv6 SID is entirely up to the 286 originator of the advertisement. In practice the function may likely 287 be End.DX6 or End.DT6. 289 3.3. Global IPv4 over SRv6 Core 291 IPv4 over IPv6 Core is defined in [RFC5549]. The MP_REACH_NLRI is 292 encoded with: 294 o AFI = 1 296 o SAFI = 1 298 o Length of Next Hop Network Address = 16 (or 32) 300 o Network Address of Next Hop = IPv6 address of Next Hop 302 o NLRI = IPv4 routes 304 SRv6 Global SID are encoded as part of the SRv6 SID TLV defined in 305 Section 2. The function of the IPv6 SRv6 SID is entirely up to the 306 originator of the advertisement. In practice, the function may 307 likely be End.DX6 or End.DT6. 309 3.4. Global IPv6 over SRv6 Core 311 IPv4 over IPv6 Core is defined in . The MP_REACH_NLRI is encoded 312 with: 314 o AFI = 2 316 o SAFI = 1 318 o Length of Next Hop Network Address = 16 (or 32) 320 o Network Address of Next Hop = IPv6 address of Next Hop 322 o NLRI = IPv6 routes 324 SRv6 Global SID are encoded as part of the SRv6 SID TLV defined in 325 Section 2. The function of the IPv6 SRv6 SID is entirely up to the 326 originator of the advertisement. In practice, the function may 327 likely be End.DX6 or End.DT6. 329 Also, by utilizing the SRv6 SID TLV, as defined in Section 2, to 330 encode the Global SID, BGP free core is possible by encapsulating all 331 BGP traffic from edge to edge over SRv6. 333 4. BGP based Ethernet VPN(EVPN) over SRv6 335 Ethernet VPN(EVPN), as defined in [RFC7432] provides an extendable 336 method of building an EVPN overlay. It primarily focuses on MPLS 337 based EVPNs but calls out the extensibility to IP based EVPN 338 overlays. It defines 4 route-types which carry prefixes and MPLS 339 Label attributes, the Labels each have specific use for MPLS 340 encapsulation of EVPN traffic. The fifth route-type carrying MPLS 341 label information (and thus encapsulation information) for EVPN is 342 defined in[I-D.ietf-bess-evpn-prefix-advertisement]. The Route Types 343 discussed below are: 345 o Ethernet Auto-discovery Route 347 o MAC/IP Advertisement Route 349 o Inclusive Multicast Ethernet Tag Route 351 o Ethernet Segment route 353 o IP prefix route 355 o Selective Multicast route 357 o IGMP join sync route 359 o IGMP leave sync route 361 To support SRv6 based EVPN overlays a SID is advertised in route-type 362 1,2,3 and 5 above. The SID (or SIDs) per route-type are advertised 363 in a new SRv6-VPN SID TLV which is optional transitive BGP Prefix SID 364 attribute. This attribute serves two purposes; first it indicates 365 that the BGP egress device is reachable via an SRv6 underlay and the 366 BGP ingress device receiving this route MAY choose to encapsulate or 367 insert an SRv6 SRH, second it indicates the value of the SID or SIDs 368 to include in the SRH encapsulation. A BGP speaker supporting an 369 SRv6 underlay MAY distribute SIDs per route via the BGP SRv6 370 Attribute. If the BGP speaker supports MPLS based EVPN 371 simultaneously it MAY also populate the Label values in EVPN route 372 types and allow the BGP ingress device to decide which encapsulation 373 to use. If the BGP speaker does not support MPLS based EVPN services 374 the MPLS Labels in EVPN route types MUST be set to IMPLICIT-NULL. 376 4.1. Ethernet Auto-discovery Route over SRv6 Core 378 Ethernet Auto-discovery (A-D) routes are Type-1 route type defined in 379 [RFC7432]and may be used to achieve split horizon filtering, fast 380 convergence and aliasing. EVPN route type-1 is also used in EVPN- 381 VPWS as well as in EVPN flexible cross-connect; mainly used to 382 advertise point-to-point services id. 384 Multi-homed PEs MAY advertise an Ethernet auto discovery route per 385 Ethernet segment with the introduced ESI MPLS label extended 386 community defined in [RFC7432]. PEs may identify other PEs connected 387 to the same Ethernet segment after the EVPN type-4 ES route exchange. 388 All the multi-homed and remote PEs that are part of same EVI may 389 import the auto discovery route. 391 EVPN Route Type-1 is encoded as follows for SRv6 Core: 393 +---------------------------------------+ 394 | RD (8 octets) | 395 +---------------------------------------+ 396 |Ethernet Segment Identifier (10 octets)| 397 +---------------------------------------+ 398 | Ethernet Tag ID (4 octets) | 399 +---------------------------------------+ 400 | MPLS label (3 octets) | 401 +---------------------------------------+ 403 For a SRv6 only BGP speaker for an SRv6 Core: 405 o SRv6-VPN SID TLV MAY be advertised with the route. 407 4.1.1. EVPN Route Type-1(Per ES AD) 409 Where: 411 o BGP next-hop: IPv6 address of an egress PE 413 o Ethernet Tag ID: all FFFF's 415 o MPLS Label: always set to zero value 417 o Extended Community: Per ES AD, ESI label extended community 419 SRv6-VPN TLV MAY be advertised along with the route advertisement and 420 the behavior of the SRv6-VPN SID is entirely up to the originator of 421 the advertisement. In practice, the behavior would likely be 422 Arg.FE2. 424 4.1.2. Prefix Type-1(Per EVI/ES AD) 426 Where: 428 o BGP next-hop: IPv6 address of an egress PE 429 o Ethernet Tag ID: non-zero for VLAN aware bridging, EVPN VPWS and 430 FXC 432 o MPLS Label: Implicit-Null 434 SRv6-VPN TLV MAY be advertised along with the route advertisement and 435 the behavior of the SRv6-VPN SID is entirely up to the originator of 436 the advertisement. In practice, the behavior would likely be 437 END.DX2, END.DX2V or END.DT2U. 439 4.2. MAC/IP Advertisement Route(Type-2) with SRv6 Core 441 EVPN route type-2 is used to advertise unicast traffic MAC+IP address 442 reachability through MP-BGP to all other PEs in a given EVPN 443 instance. 445 A MAC/IP Advertisement route type is encoded as follows for SRv6 446 Core: 448 +---------------------------------------+ 449 | RD (8 octets) | 450 +---------------------------------------+ 451 |Ethernet Segment Identifier (10 octets)| 452 +---------------------------------------+ 453 | Ethernet Tag ID (4 octets) | 454 +---------------------------------------+ 455 | MAC Address Length (1 octet) | 456 +---------------------------------------+ 457 | MAC Address (6 octets) | 458 +---------------------------------------+ 459 | IP Address Length (1 octet) | 460 +---------------------------------------+ 461 | IP Address (0, 4, or 16 octets) | 462 +---------------------------------------+ 463 | MPLS Label1 (3 octets) | 464 +---------------------------------------+ 465 | MPLS Label2 (0 or 3 octets) | 466 +---------------------------------------+ 468 where: 470 o BGP next-hop: IPv6 address of an egress PE 472 o MPLS Label1: Implicit-null 474 o MPLS Label2: Implicit-null 475 SRv6-VPN SID TLV MAY be advertised. The behavior of the SRv6-VPN SID 476 is entirely up to the originator of the advertisement. In practice, 477 the behavior of the SRv6 SID is as follows: 479 o END.DX2, END.DT2U (Layer 2 portion of the route) 481 o END.DT6/4 or END.DX6/4 (Layer 3 portion of the route) 483 Described below are different types of Type-2 advertisements. 485 o MAC/IP Advertisement Route(Type-2) with MAC Only 487 * BGP next-hop: IPv6 address of egress PE 489 * MPLS Label1: Implicit-null 491 * MPLS Label2: Implicit-null 493 * SRv6-VPN SID TLV MAY encode END.DX2 or END.DT2U behavior 495 o MAC/IP Advertisement Route(Type-2) with MAC+IP 497 * BGP next-hop: IPv6 address of egress PE 499 * MPLS Label1: Implicit-Null 501 * MPLS Label2: Implicit-Null 503 * SRv6-VPN SID TLV MAY encode Layer2 END.DX2 or END.DT2U behavior 504 and Layer3 END.DT6/4 or END.DX6/4 behavior 506 4.3. Inclusive Multicast Ethernet Tag Route with SRv6 Core 508 EVPN route Type-3 is used to advertise multicast traffic reachability 509 information through MP-BGP to all other PEs in a given EVPN instance. 511 +---------------------------------------+ 512 | RD (8 octets) | 513 +---------------------------------------+ 514 | Ethernet Tag ID (4 octets) | 515 +---------------------------------------+ 516 | IP Address Length (1 octet) | 517 +---------------------------------------+ 518 | Originating Router's IP Address | 519 | (4 or 16 octets) | 520 +---------------------------------------+ 522 An Inclusive Multicast Ethernet Tag route type specific EVPN NLRI 523 consists of the following [RFC7432] where: 525 o BGP next-hop: IPv6 address of egress PE 527 o SRv6-VPN TLV MAY encode END.DX2/END.DT2M function. 529 o BGP Attribute: PMSI Tunnel Attribute[RFC6514] MAY contain MPLS 530 implicit-null label and Tunnel Type would be similar to defined in 531 EVPN Type-6 i.e. Ingress replication route. 533 The format of PMSI Tunnel Attribute attribute is encoded as follows 534 for an SRv6 Core: 536 +---------------------------------------+ 537 | Flag (1 octet) | 538 +---------------------------------------+ 539 | Tunnel Type (1 octet) | 540 +---------------------------------------+ 541 | MPLS label (3 octet) | 542 +---------------------------------------+ 543 | Tunnel Identifier (variable) | 544 +---------------------------------------+ 546 o Flag: zero value defined per [RFC7432] 548 o Tunnel Type: defined per [RFC6514] 550 o MPLS label: Implicit-Null 552 o Tunnel Identifier: IP address of egress PE 554 SRv6 SID MAY be encoded as part of the SRv6-VPN SID TLV. The 555 behavior of the SRv6-VPN SID is entirely up to the originator of the 556 advertisement. In practice, the behavior of the SRv6 SID is as 557 follows: 559 o END.DX2 or END.DT2M function 561 o The lower 32 bits of the SRv6-VPN SID TLV MAY be all zero's. The 562 ESI Filtering argument(Arg.FE2) carried along with EVPN Route 563 Type-1 MAY be merged together by doing a bitwise logical OR to 564 create a single SID on the ingress PE for Split-horizon and other 565 filtering mechanisms. Details of filtering mechanisms are 566 described in[RFC7432] 568 4.4. Ethernet Segment Route with SRv6 Core 570 An Ethernet Segment route type specific EVPN NLRI consists of the 571 following defined in [RFC7432] 573 +---------------------------------------+ 574 | RD (8 octets) | 575 +---------------------------------------+ 576 | Ethernet Tag ID (4 octets) | 577 +---------------------------------------+ 578 | IP Address Length (1 octet) | 579 +---------------------------------------+ 580 | Originating Router's IP Address | 581 | (4 or 16 octets) | 582 +---------------------------------------+ 584 where: 586 o BGP next-hop: IPv6 address of egress PE 588 As oppose as previous route types, SRv6-VPN TLV is NOT advertised 589 along with the route. The processing of that route has not changed; 590 it remains as described in [RFC7432]. 592 4.5. IP prefix router(Type-5) with SRv6 Core 594 EVPN route Type-5 is used to advertise IP address reachability 595 through MP-BGP to all other PEs in a given EVPN instance. IP address 596 may include host IP prefix or any specific subnet. EVPN route Type-5 597 is defined in[I-D.ietf-bess-evpn-prefix-advertisement] 599 An IP Prefix advertisement is encoded as follows for an SRv6 Core: 601 +---------------------------------------+ 602 | RD (8 octets) | 603 +---------------------------------------+ 604 |Ethernet Segment Identifier (10 octets)| 605 +---------------------------------------+ 606 | Ethernet Tag ID (4 octets) | 607 +---------------------------------------+ 608 | IP Prefix Length (1 octet) | 609 +---------------------------------------+ 610 | IP Prefix (4 or 16 octets) | 611 +---------------------------------------+ 612 | GW IP Address (4 or 16 octets) | 613 +---------------------------------------+ 614 | MPLS Label (3 octets) | 615 +---------------------------------------+ 617 o BGP next-hop: IPv6 address of egress PE 619 o MPLS Label: Implicit-Null 621 SRv6-VPN SID TLV MAY be advertised. The behavior of the SRv6-VPN SID 622 is entirely up to the originator of the advertisement. In practice, 623 the behavior of the SRv6 SID is an End.DT6/4 or End.DX6/4. 625 4.6. Multicast routes (EVPN Route Type-6, Type-7, Type-8) 627 These routes do not require any additional SRv6-VPN TLV. As per EVPN 628 route-type 4, the BGP nexthop is equal to the IPv6 address of egress 629 PE. More details may be added in future revisions of this document. 631 5. Migration from L3 MPLS based Segment Routing to SRv6 Segment Routing 633 Migration from MPLS to an SRv6 with BGP speakers is achieved with BGP 634 sessions per BGP instance, one for IPv4 and a one for IPv6. 635 Migration from IPv4 to IPv6 is independent of SRv6 BGP endpoints, and 636 the selection of which route to use (received via the IPv4 or IPv6 637 session) is a local configurable decision of the ingress-PE, and is 638 outside the scope of this document. 640 Migration from IPv6 MPLS based underlay to an SRv6 underlay with BGP 641 speakers is achieved with a few simple rules at each BGP speaker. 643 At Egress-PE 644 If BGP offers an SRv6-VPN service 645 Then BGP allocates an SRv6-VPN SID for the VPN service 646 and adds the BGP SRv6-VPN SID TLV while advertising VPN prefixes. 647 If BGP offers an MPLS VPN service 648 Then BGP allocates an MPLS Label for the VPN service and 649 use it in NLRI as normal for MPLS L3 VPNs. 650 else MPLS label for VPN service is set to IMPLICIT-NULL. 652 At Ingress-PE 653 *Selection of which encapsulation below (SRv6-VPN or MPLS-VPN) is 654 defined by local BGP policy 655 If BGP supports SRv6-VPN service, and 656 receives a BGP SRv6-VPN SID Attribute with an SRv6 SID 657 Then BGP programs the destination prefix in RIB recursive via 658 the related SR Policy. 659 If BGP supports MPLS VPN service, and 660 the MPLS Label is not Implicit-Null 661 Then the MPLS label is used as a VPN label and inserted with the 662 prefix into RIB via the BGP Nexthop. 664 6. Implementation Status 666 The SRv6-VPN is available for SRv6 on various Cisco hardware and 667 other software platforms. An end-to-end integration of SRv6 L3VPN, 668 SRv6 Traffic-Engineering and Service Chaining. All of that with 669 data-plane interoperability across different implementations [1]: 671 o Three Cisco Hardware-forwarding platforms: ASR 1K, ASR 9k and NCS 672 5500 674 o Two Cisco network operating systems: IOS XE and IOS XR 676 o Barefoot Networks Tofino on OCP Wedge-100BF 678 o Linux Kernel officially upstreamed in 4.10 680 o Fd.io 682 7. Error Handling of BGP SRv6 SID Updates 684 When a BGP Speaker receives a BGP Update message containing a 685 malformed SRv6-VPN SID TLV, it MUST ignore the received BGP 686 attributes and not pass it to other BGP peers. This is equivalent to 687 the -attribute discard- action specified in [RFC7606]. When 688 discarding an attribute, a BGP speaker MAY log an error for further 689 analysis. 691 8. IANA Considerations 693 This document defines a new TLV types as part of the BGP Prefix SID 694 attribute. 696 9. Security Considerations 698 This document introduces no new security considerations beyond those 699 already specified in [RFC4271] and [RFC3107]. 701 10. Conclusions 703 This document proposes extensions to the BGP to allow advertising 704 certain attributes and functionalities related to SRv6. 706 11. References 707 11.1. Normative References 709 [I-D.filsfils-spring-segment-routing-policy] 710 Filsfils, C., Sivabalan, S., Raza, K., Liste, J., Clad, 711 F., Lin, S., bogdanov@google.com, b., Horneffer, M., 712 Steinberg, D., Decraene, B., and S. Litkowski, "Segment 713 Routing Policy for Traffic Engineering", draft-filsfils- 714 spring-segment-routing-policy-01 (work in progress), July 715 2017. 717 [I-D.filsfils-spring-srv6-network-programming] 718 Filsfils, C., Leddy, J., daniel.voyer@bell.ca, d., 719 daniel.bernier@bell.ca, d., Steinberg, D., Raszuk, R., 720 Matsushima, S., Lebrun, D., Decraene, B., Peirens, B., 721 Salsano, S., Naik, G., Elmalky, H., Jonnalagadda, P., 722 Sharif, M., Ayyangar, A., Mynam, S., Henderickx, W., 723 Bashandy, A., Raza, K., Dukes, D., Clad, F., and P. 724 Camarillo, "SRv6 Network Programming", draft-filsfils- 725 spring-srv6-network-programming-01 (work in progress), 726 June 2017. 728 [I-D.ietf-6man-segment-routing-header] 729 Previdi, S., Filsfils, C., Raza, K., Leddy, J., Field, B., 730 daniel.voyer@bell.ca, d., daniel.bernier@bell.ca, d., 731 Matsushima, S., Leung, I., Linkova, J., Aries, E., Kosugi, 732 T., Vyncke, E., Lebrun, D., Steinberg, D., and R. Raszuk, 733 "IPv6 Segment Routing Header (SRH)", draft-ietf-6man- 734 segment-routing-header-07 (work in progress), July 2017. 736 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 737 (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460, 738 December 1998, . 740 [RFC3107] Rekhter, Y. and E. Rosen, "Carrying Label Information in 741 BGP-4", RFC 3107, DOI 10.17487/RFC3107, May 2001, 742 . 744 [RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private 745 Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February 746 2006, . 748 [RFC4456] Bates, T., Chen, E., and R. Chandra, "BGP Route 749 Reflection: An Alternative to Full Mesh Internal BGP 750 (IBGP)", RFC 4456, DOI 10.17487/RFC4456, April 2006, 751 . 753 [RFC6514] Aggarwal, R., Rosen, E., Morin, T., and Y. Rekhter, "BGP 754 Encodings and Procedures for Multicast in MPLS/BGP IP 755 VPNs", RFC 6514, DOI 10.17487/RFC6514, February 2012, 756 . 758 [RFC7432] Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A., 759 Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based 760 Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432, February 761 2015, . 763 [RFC7606] Chen, E., Ed., Scudder, J., Ed., Mohapatra, P., and K. 764 Patel, "Revised Error Handling for BGP UPDATE Messages", 765 RFC 7606, DOI 10.17487/RFC7606, August 2015, 766 . 768 11.2. Informative References 770 [I-D.ietf-bess-evpn-prefix-advertisement] 771 Rabadan, J., Henderickx, W., Drake, J., Lin, W., and A. 772 Sajassi, "IP Prefix Advertisement in EVPN", draft-ietf- 773 bess-evpn-prefix-advertisement-06 (work in progress), 774 October 2017. 776 [I-D.ietf-idr-bgp-prefix-sid] 777 Previdi, S., Filsfils, C., Lindem, A., Sreekantiah, A., 778 and H. Gredler, "Segment Routing Prefix SID extensions for 779 BGP", draft-ietf-idr-bgp-prefix-sid-06 (work in progress), 780 June 2017. 782 [I-D.ietf-isis-segment-routing-extensions] 783 Previdi, S., Filsfils, C., Bashandy, A., Gredler, H., 784 Litkowski, S., Decraene, B., and j. jefftant@gmail.com, 785 "IS-IS Extensions for Segment Routing", draft-ietf-isis- 786 segment-routing-extensions-13 (work in progress), June 787 2017. 789 [I-D.ietf-spring-segment-routing] 790 Filsfils, C., Previdi, S., Decraene, B., Litkowski, S., 791 and R. Shakir, "Segment Routing Architecture", draft-ietf- 792 spring-segment-routing-12 (work in progress), June 2017. 794 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 795 Requirement Levels", BCP 14, RFC 2119, 796 DOI 10.17487/RFC2119, March 1997, 797 . 799 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 800 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 801 DOI 10.17487/RFC4271, January 2006, 802 . 804 [RFC4659] De Clercq, J., Ooms, D., Carugi, M., and F. Le Faucheur, 805 "BGP-MPLS IP Virtual Private Network (VPN) Extension for 806 IPv6 VPN", RFC 4659, DOI 10.17487/RFC4659, September 2006, 807 . 809 [RFC5549] Le Faucheur, F. and E. Rosen, "Advertising IPv4 Network 810 Layer Reachability Information with an IPv6 Next Hop", 811 RFC 5549, DOI 10.17487/RFC5549, May 2009, 812 . 814 11.3. URIs 816 [1] http://www.segment-routing.net 818 Appendix A. Contributors 820 Bart Peirens 821 Proximus 822 Belgium 824 Email: bart.peirens@proximus.com 826 Authors' Addresses 828 Gaurav Dawra (editor) 829 Cisco Systems 830 USA 832 Email: gdawra@cisco.com 834 Clarence Filsfils 835 Cisco Systems 836 Belgium 838 Email: cfilsfil@cisco.com 839 Darren Dukes 840 Cisco Systems 841 Canada 843 Email: ddukes@cisco.com 845 Patrice Brissette 846 Cisco Systems 847 Canada 849 Email: pbrisset@cisco.com 851 Pablo Camarilo 852 Cisco Systems 853 Spain 855 Email: pcamaril@cisco.com 857 Jonn Leddy 858 Comcast 859 USA 861 Email: john_leddy@cable.comcast.com 863 Daniel Voyer 864 Bell Canada 865 Canada 867 Email: daniel.voyer@bell.ca 869 Daniel Bernier 870 Bell Canada 871 Canada 873 Email: daniel.bernier@bell.ca 875 Dirk Steinberg 876 Steinberg Consulting 877 Germany 879 Email: dws@steinberg.net 880 Robert Raszuk 881 Bloomberg LP 882 USA 884 Email: robert@raszuk.net 886 Bruno Decraene 887 Orange 888 France 890 Email: bruno.decraene@orange.com 892 Satoru Matsushima 893 SoftBank 894 1-9-1,Higashi-Shimbashi,Minato-Ku 895 Japan 105-7322 897 Email: satoru.matsushima@g.softbank.co.jp