idnits 2.17.1 draft-ietf-bier-ospf-bier-extensions-07.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (July 3, 2017) is 2486 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-08) exists of draft-ietf-bier-architecture-06 == Outdated reference: A later version (-12) exists of draft-ietf-bier-mpls-encapsulation-07 Summary: 0 errors (**), 0 flaws (~~), 3 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 OSPF P. Psenak, Ed. 3 Internet-Draft N. Kumar 4 Intended status: Standards Track IJ. Wijnands 5 Expires: January 4, 2018 Cisco 6 A. Dolganow 7 Nokia 8 T. Przygienda 9 J. Zhang 10 Juniper Networks, Inc. 11 S. Aldrin 12 Google, Inc. 13 July 3, 2017 15 OSPF Extensions for BIER 16 draft-ietf-bier-ospf-bier-extensions-07.txt 18 Abstract 20 Bit Index Explicit Replication (BIER) is an architecture that 21 provides multicast forwarding through a "BIER domain" without 22 requiring intermediate routers to maintain multicast related per-flow 23 state. Neither does BIER require an explicit tree-building protocol 24 for its operation. A multicast data packet enters a BIER domain at a 25 "Bit-Forwarding Ingress Router" (BFIR), and leaves the BIER domain at 26 one or more "Bit-Forwarding Egress Routers" (BFERs). The BFIR router 27 adds a BIER header to the packet. Such header contains a bit-string 28 in which each bit represents exactly one BFER to forward the packet 29 to. The set of BFERs to which the multicast packet needs to be 30 forwarded is expressed by the according set of bits set in BIER 31 packet header. 33 This document describes the OSPF protocol extension required for BIER 34 with MPLS encapsulation. 36 Status of This Memo 38 This Internet-Draft is submitted in full conformance with the 39 provisions of BCP 78 and BCP 79. 41 Internet-Drafts are working documents of the Internet Engineering 42 Task Force (IETF). Note that other groups may also distribute 43 working documents as Internet-Drafts. The list of current Internet- 44 Drafts is at http://datatracker.ietf.org/drafts/current/. 46 Internet-Drafts are draft documents valid for a maximum of six months 47 and may be updated, replaced, or obsoleted by other documents at any 48 time. It is inappropriate to use Internet-Drafts as reference 49 material or to cite them other than as "work in progress." 51 This Internet-Draft will expire on January 4, 2018. 53 Copyright Notice 55 Copyright (c) 2017 IETF Trust and the persons identified as the 56 document authors. All rights reserved. 58 This document is subject to BCP 78 and the IETF Trust's Legal 59 Provisions Relating to IETF Documents 60 (http://trustee.ietf.org/license-info) in effect on the date of 61 publication of this document. Please review these documents 62 carefully, as they describe your rights and restrictions with respect 63 to this document. Code Components extracted from this document must 64 include Simplified BSD License text as described in Section 4.e of 65 the Trust Legal Provisions and are provided without warranty as 66 described in the Simplified BSD License. 68 Table of Contents 70 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 71 2. Flooding of the BIER Information in OSPF . . . . . . . . . . 3 72 2.1. BIER Sub-TLV . . . . . . . . . . . . . . . . . . . . . . 3 73 2.2. BIER MPLS Encapsulation Sub-TLV . . . . . . . . . . . . . 4 74 2.3. Optional BIER Tree Type Sub-TLV . . . . . . . . . . . . . 5 75 2.4. Optional BIER sub-domain BSL conversion Sub-TLV . . . . . 6 76 2.5. Flooding scope of BIER Information . . . . . . . . . . . 7 77 3. Security Considerations . . . . . . . . . . . . . . . . . . . 7 78 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 79 5. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8 80 6. Normative References . . . . . . . . . . . . . . . . . . . . 8 81 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 83 1. Introduction 85 Bit Index Explicit Replication (BIER) is an architecture that 86 provides optimal multicast forwarding through a "BIER domain" without 87 requiring intermediate routers to maintain any multicast related per- 88 flow state. Neither does BIER explicitly require a tree-building 89 protocol for its operation. A multicast data packet enters a BIER 90 domain at a "Bit-Forwarding Ingress Router" (BFIR), and leaves the 91 BIER domain at one or more "Bit-Forwarding Egress Routers" (BFERs). 92 The BFIR router adds a BIER header to the packet. The BIER header 93 contains a bit-string in which each bit represents exactly one BFER 94 to forward the packet to. The set of BFERs to which the multicast 95 packet needs to be forwarded is expressed by setting the bits that 96 correspond to those routers in the BIER header. 98 BIER architecture requires routers participating in BIER to exchange 99 BIER related information within a given domain. BIER architecture 100 permits link-state routing protocols to perform distribution of such 101 information. This document describes extensions to OSPF necessary to 102 advertise BIER specific information in the case where BIER uses MPLS 103 encapsulation as described in [I-D.ietf-bier-mpls-encapsulation]. 105 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 106 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 107 document are to be interpreted as described in [RFC2119]. 109 2. Flooding of the BIER Information in OSPF 111 All BIER specific information that a Bit-Forwarding Router (BFR) 112 needs to advertise to other BFRs is associated with a BFR-Prefix. A 113 BFR prefix is a unique (within a given BIER domain) routable IP 114 address that is assigned to each BFR as described in more detail in 115 section 2 of [I-D.ietf-bier-architecture]. 117 Given that BIER information must be associated with a BFR prefix, the 118 OSPF Extended Prefix Opaque LSA [RFC7684] has been chosen for 119 advertisement. 121 2.1. BIER Sub-TLV 123 A Sub-TLV of the Extended Prefix TLV (defined in [RFC7684]) is 124 defined for distributing BIER information. The Sub-TLV is called the 125 BIER Sub-TLV. Multiple BIER Sub-TLVs may be included in the Extended 126 Prefix TLV. 128 The BIER Sub-TLV has the following format: 130 0 1 2 3 131 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 1 132 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 133 | Type | Length | 134 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 135 | Sub-domain-ID | MT-ID | BFR-id | 136 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 137 | Sub-TLVs (variable) | 138 +- -+ 139 | | 141 Type: TBD1 142 Length: variable 144 Sub-domain-ID: Unique value identifying the BIER sub-domain within 145 the BIER domain, as described in section 1 of 146 [I-D.ietf-bier-architecture]. 148 MT-ID: Multi-Topology ID (as defined in [RFC4915]) that identifies 149 the topology that is associated with the BIER sub-domain. 151 BFR-id: A 2 octet field encoding the BFR-id, as documented in 152 section 2 of [I-D.ietf-bier-architecture]. If the BFR is not 153 locally configured with a valid BFR-id, the value of this field is 154 set to invalid BFR-id per [I-D.ietf-bier-architecture]. 156 Each BFR sub-domain MUST be associated with one and only one OSPF 157 topology that is identified by the MT-ID. If the association between 158 BIER sub-domain and OSPF topology advertised in the BIER sub-TLV by 159 other BFRs is in conflict with the association locally configured on 160 the receiving router, the BIER Sub-TLV MUST be ignored. 162 If a BFR advertises the same Sub-domain-ID in multiple BIER sub-TLVs, 163 the BRF MUST be treated as if it did not advertise a BIER sub-TLV for 164 such sub-domain. 166 All BFRs MUST detect advertisement of duplicate valid BFR-IDs for a 167 given MT-ID and Sub-domain-ID. When such duplication is detected all 168 BFRs advertising duplicates MUST be treated as if they did not 169 advertise a valid BFR-id. 171 2.2. BIER MPLS Encapsulation Sub-TLV 173 The BIER MPLS Encapsulation Sub-TLV is a Sub-TLV of the BIER Sub-TLV. 174 The BIER MPLS Encapsulation Sub-TLV is used in order to advertise 175 MPLS specific information used for BIER. It MAY appear multiple 176 times in the BIER Sub-TLV. 178 The BIER MPLS Encapsulation Sub-TLV has the following format: 180 0 1 2 3 181 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 1 182 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 183 | Type | Length | 184 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 185 |Lbl Range Size | Label Range Base | 186 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 187 | BS Length | Reserved | 188 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 189 Type: TBD2 191 Length: 4 octets 193 Label Range Size: A 1 octet field encoding the label range size of 194 the label range. It MUST be greater then 0, otherwise the 195 advertising router MUST be treated as if it did not advertise a 196 BIER sub-TLV. 198 Label Range Base: A 3 octet field, where the 20 rightmost bits 199 represent the first label in the label range. 201 Bit String Length: A 1 octet field encoding the supported 202 BitString length associated with this BFR-prefix. The values 203 allowed in this field are specified in section 2 of 204 [I-D.ietf-bier-mpls-encapsulation]. 206 The "label range" is the set of labels beginning with the label 207 range base and ending with ((label range base)+(label range size)- 208 1). A unique label range is allocated for each BitStream length 209 and Sub-domain-ID. These labels are used for BIER forwarding as 210 described in [I-D.ietf-bier-architecture] and 211 [I-D.ietf-bier-mpls-encapsulation]. 213 The size of the label range is determined by the number of Set 214 Identifiers (SI) (section 1 of [I-D.ietf-bier-architecture]) that 215 are used in the network. Each SI maps to a single label in the 216 label range. The first label is for SI=0, the second label is for 217 SI=1, etc. 219 If same BS length is repeated in multiple BIER MPLS Encapsulation 220 Sub-TLV inside the same BIER Sub-TLV, the BIER sub-TLV MUST be 221 ignored. 223 Label ranges within all BIER MPLS Encapsulation Sub-TLV inside the 224 same BIER Sub-TLV MUST NOT overlap. If the overlap is detected, the 225 advertising router MUST be treated as if it did not advertise a BIER 226 sub-TLV. 228 All advertised labels MUST be valid, otherwise the BIER sub-TLV MUST 229 be ignored. 231 2.3. Optional BIER Tree Type Sub-TLV 233 The BIER Tree Type Sub-TLV is a Sub-TLV of the BIER Sub-TLV. This 234 Sub-TLV carries the information associated with the supported BIER 235 tree type for a sub-domain. This Sub-TLV is optional and its absence 236 has the same semantics as its presence with Tree Type value 0 (SPF). 238 When Tree Type 0 is used, it is RECOMMENDED that this Sub-TLV is 239 omitted in order to reduce the space consumed in the parent TLV. 241 This Sub-TLV MAY occur no more than once in a BIER sub-TLV. If 242 multiple occurences of this Sub-TLV are present in a single BIER Sub- 243 TLV, the BIER sub-TLV MUST be ignored. 245 If the tree type (implied or explicitly advertised) does not match 246 the locally configured tree type associated with the matching sub- 247 domain, the BIER sub-TLV MUST be ignored. 249 0 1 2 3 250 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 1 251 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 252 | Type | Length | 253 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 254 | Tree Type | 255 +-+-+-+-+-+-+-+-+ 257 Type: TBD3. 259 Length: 1 octet. 261 Tree Type: 1 octet 263 2.4. Optional BIER sub-domain BSL conversion Sub-TLV 265 The BIER sub-domain BSL conversion Sub-TLV is a Sub-TLV of the BIER 266 Sub-TLV. This sub-TLV indicates whether the BFR is capable of 267 imposing a different Bit String Length (BSL) than the one it received 268 in a BIER encapsulated packet. Such a capability may allow future, 269 advanced tree types which ensure simple migration procedures from one 270 BSL to another in a given MT-ID and Sub-domain-ID or prevent stable 271 blackholes in scenarios where not all routers support the same set of 272 BSLs in a given MT-ID and Sub-domain-ID. 274 The BIER sub-domain BSL conversion Sub-TLV is optional and its 275 absence indicates that the router is NOT capable of imposing 276 different BSLs but will always forward the packet with the BSL 277 unchanged. This sub-TLV MAY occur at most once in a given BIER sub- 278 TLV. If multiple occurrences of this sub-TLV are received in a given 279 BIER sub-TLV, the BIER sub-TLV MUST be ignored. 281 The BIER sub-domain BSL conversion Sub-TLV has following format: 283 0 1 2 3 284 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 1 285 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 286 | Type | Length | 287 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 289 Type: TBD4. 291 Length: 0 octets. 293 2.5. Flooding scope of BIER Information 295 The flooding scope of the OSPF Extended Prefix Opaque LSA [RFC7684] 296 that is used for advertising the BIER Sub-TLV is set to area-local. 297 To allow BIER deployment in a multi-area environment, OSPF must 298 propagate BIER information between areas. The following procedure is 299 used in order to propagate BIER related information between areas: 301 When an OSPF Area Border Router (ABR) advertises a Type-3 Summary 302 LSA from an intra-area or inter-area prefix to all its attached 303 areas, it will also originate an Extended Prefix Opaque LSA, as 304 described in [RFC7684]. The flooding scope of the Extended Prefix 305 Opaque LSA type will be set to area-local. The route-type in the 306 OSPF Extended Prefix TLV is set to inter-area. When determining 307 whether a BIER Sub-TLV should be included in this LSA, an OSPF ABR 308 will: 310 - Examine its best path to the prefix in the source area and 311 find the advertising router associated with the best path to 312 that prefix. 314 - Determine if such advertising router advertised a BIER Sub- 315 TLV for the prefix. If yes, the ABR will copy the information 316 from such BIER MPLS Sub-TLV when advertising BIER MPLS Sub-TLV 317 to each attached area. 319 3. Security Considerations 321 Implementations must assure that malformed TLV and Sub-TLV 322 permutations do not result in errors which cause hard OSPF failures. 324 4. IANA Considerations 326 The document requests three new allocations from the OSPF Extended 327 Prefix sub-TLV registry as defined in [RFC7684]. 329 BIER Sub-TLV: TBD1 330 BIER MPLS Encapsulation Sub-TLV: TBD2 332 BIER Tree Type Sub-TLV: TBD3 334 BIER sub-domain BSL conversion Sub-TLV 336 5. Acknowledgments 338 The authors would like to thank Rajiv Asati, Christian Martin, Greg 339 Shepherd and Eric Rosen for their contribution. 341 6. Normative References 343 [I-D.ietf-bier-architecture] 344 Wijnands, I., Rosen, E., Dolganow, A., Przygienda, T., and 345 S. Aldrin, "Multicast using Bit Index Explicit 346 Replication", draft-ietf-bier-architecture-06 (work in 347 progress), April 2017. 349 [I-D.ietf-bier-mpls-encapsulation] 350 Wijnands, I., Rosen, E., Dolganow, A., Tantsura, J., 351 Aldrin, S., and I. Meilik, "Encapsulation for Bit Index 352 Explicit Replication in MPLS and non-MPLS Networks", 353 draft-ietf-bier-mpls-encapsulation-07 (work in progress), 354 June 2017. 356 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 357 Requirement Levels", BCP 14, RFC 2119, 358 DOI 10.17487/RFC2119, March 1997, 359 . 361 [RFC4915] Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P. 362 Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF", 363 RFC 4915, DOI 10.17487/RFC4915, June 2007, 364 . 366 [RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W., 367 Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute 368 Advertisement", RFC 7684, DOI 10.17487/RFC7684, November 369 2015, . 371 Authors' Addresses 372 Peter Psenak (editor) 373 Cisco 374 Apollo Business Center 375 Mlynske nivy 43 376 Bratislava 821 09 377 Slovakia 379 Email: ppsenak@cisco.com 381 Nagendra Kumar 382 Cisco 383 7200 Kit Creek Road 384 Research Triangle Park, NC 27709 385 US 387 Email: naikumar@cisco.com 389 IJsbrand Wijnands 390 Cisco 391 De Kleetlaan 6a 392 Diegem 1831 393 Belgium 395 Email: ice@cisco.com 397 Andrew Dolganow 398 Nokia 399 750 Chai Chee Rd 400 06-06 Viva Business Park 401 Singapore 469004 403 Email: andrew.dolganow@alcatel-lucent.com 405 Tony Przygienda 406 Juniper Networks, Inc. 407 10 Technology Park Drive 408 Westford, MA 01886 409 USA 411 Email: prz@juniper.net 412 Jeffrey Zhang 413 Juniper Networks, Inc. 414 10 Technology Park Drive 415 Westford, MA 01886 416 USA 418 Email: zzhang@juniper.net 420 Sam Aldrin 421 Google, Inc. 422 1600 Amphitheatre Parkway 423 Mountain View, CA 424 USA 426 Email: aldrin.ietf@gmail.com