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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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-08) exists of draft-ietf-bier-architecture-06 == Outdated reference: A later version (-12) exists of draft-ietf-bier-mpls-encapsulation-07 Summary: 0 errors (**), 0 flaws (~~), 3 warnings (==), 1 comment (--).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: December 22, 2017 Cisco 6 A. Dolganow 7 Nokia 8 T. Przygienda 9 J. Zhang 10 Juniper Networks, Inc. 11 S. Aldrin 12 Google, Inc. 13 June 20, 2017 15 OSPF Extensions for BIER 16 draft-ietf-bier-ospf-bier-extensions-06.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 December 22, 2017. 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. Flooding scope of BIER Information . . . . . . . . . . . 6 76 3. Security Considerations . . . . . . . . . . . . . . . . . . . 7 77 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 78 5. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 7 79 6. Normative References . . . . . . . . . . . . . . . . . . . . 7 80 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 82 1. Introduction 84 Bit Index Explicit Replication (BIER) is an architecture that 85 provides optimal multicast forwarding through a "BIER domain" without 86 requiring intermediate routers to maintain any multicast related per- 87 flow state. Neither does BIER explicitly require a tree-building 88 protocol for its operation. A multicast data packet enters a BIER 89 domain at a "Bit-Forwarding Ingress Router" (BFIR), and leaves the 90 BIER domain at one or more "Bit-Forwarding Egress Routers" (BFERs). 91 The BFIR router adds a BIER header to the packet. The BIER header 92 contains a bit-string in which each bit represents exactly one BFER 93 to forward the packet to. The set of BFERs to which the multicast 94 packet needs to be forwarded is expressed by setting the bits that 95 correspond to those routers in the BIER header. 97 BIER architecture requires routers participating in BIER to exchange 98 BIER related information within a given domain. BIER architecture 99 permits link-state routing protocols to perform distribution of such 100 information. This document describes extensions to OSPF necessary to 101 advertise BIER specific information in the case where BIER uses MPLS 102 encapsulation as described in [I-D.ietf-bier-mpls-encapsulation]. 104 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 105 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 106 document are to be interpreted as described in [RFC2119]. 108 2. Flooding of the BIER Information in OSPF 110 All BIER specific information that a Bit-Forwarding Router (BFR) 111 needs to advertise to other BFRs is associated with a BFR-Prefix. A 112 BFR prefix is a unique (within a given BIER domain) routable IP 113 address that is assigned to each BFR as described in more detail in 114 section 2 of [I-D.ietf-bier-architecture]. 116 Given that BIER information must be associated with a BFR prefix, the 117 OSPF Extended Prefix Opaque LSA [RFC7684] has been chosen for 118 advertisement. 120 2.1. BIER Sub-TLV 122 A Sub-TLV of the Extended Prefix TLV (defined in [RFC7684]) is 123 defined for distributing BIER information. The Sub-TLV is called the 124 BIER Sub-TLV. Multiple BIER Sub-TLVs may be included in the Extended 125 Prefix TLV. 127 The BIER Sub-TLV has the following format: 129 0 1 2 3 130 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 1 131 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 132 | Type | Length | 133 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 134 | Sub-domain-ID | MT-ID | BFR-id | 135 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 136 | Sub-TLVs (variable) | 137 +- -+ 138 | | 140 Type: TBD1 142 Length: variable 143 Sub-domain-ID: Unique value identifying the BIER sub-domain within 144 the BIER domain, as described in section 1 of 145 [I-D.ietf-bier-architecture]. 147 MT-ID: Multi-Topology ID (as defined in [RFC4915]) that identifies 148 the topology that is associated with the BIER sub-domain. 150 BFR-id: A 2 octet field encoding the BFR-id, as documented in 151 section 2 of [I-D.ietf-bier-architecture]. If the BFR is not 152 locally configured with a valid BFR-id, the value of this field is 153 set to invalid BFR-id per [I-D.ietf-bier-architecture]. 155 Each BFR sub-domain MUST be associated with one and only one OSPF 156 topology that is identified by the MT-ID. If the association between 157 BIER sub-domain and OSPF topology advertised in the BIER sub-TLV by 158 other BFRs is in conflict with the association locally configured on 159 the receiving router, the BIER Sub-TLV MUST be ignored. 161 If a BFR advertises the same Sub-domain-ID in multiple BIER sub-TLVs, 162 the BRF MUST be treated as if it did not advertise a BIER sub-TLV for 163 such sub-domain. 165 All BFRs MUST detect advertisement of duplicate valid BFR-IDs for a 166 given MT-ID and Sub-domain-ID. When such duplication is detected all 167 BFRs advertising duplicates MUST be treated as if they did not 168 advertise a valid BFR-id. 170 2.2. BIER MPLS Encapsulation Sub-TLV 172 The BIER MPLS Encapsulation Sub-TLV is a Sub-TLV of the BIER Sub-TLV. 173 The BIER MPLS Encapsulation Sub-TLV is used in order to advertise 174 MPLS specific information used for BIER. It MAY appear multiple 175 times in the BIER Sub-TLV. 177 The BIER MPLS Encapsulation Sub-TLV has the following format: 179 0 1 2 3 180 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 1 181 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 182 | Type | Length | 183 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 184 |Lbl Range Size | Label Range Base | 185 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 186 | BS Length | Reserved | 187 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 189 Type: TBD2 190 Length: 4 octets 192 Label Range Size: A 1 octet field encoding the label range size of 193 the label range. It MUST be greater then 0, otherwise the 194 advertising router MUST be treated as if it did not advertise a 195 BIER sub-TLV. 197 Label Range Base: A 3 octet field, where the 20 rightmost bits 198 represent the first label in the label range. 200 Bit String Length: A 1 octet field encoding the supported 201 BitString length associated with this BFR-prefix. The values 202 allowed in this field are specified in section 2 of 203 [I-D.ietf-bier-mpls-encapsulation]. 205 The "label range" is the set of labels beginning with the label 206 range base and ending with ((label range base)+(label range size)- 207 1). A unique label range is allocated for each BitStream length 208 and Sub-domain-ID. These labels are used for BIER forwarding as 209 described in [I-D.ietf-bier-architecture] and 210 [I-D.ietf-bier-mpls-encapsulation]. 212 The size of the label range is determined by the number of Set 213 Identifiers (SI) (section 1 of [I-D.ietf-bier-architecture]) that 214 are used in the network. Each SI maps to a single label in the 215 label range. The first label is for SI=0, the second label is for 216 SI=1, etc. 218 If same BS length is repeated in multiple BIER MPLS Encapsulation 219 Sub-TLV inside the same BIER Sub-TLV, the BIER sub-TLV MUST be 220 ignored. 222 Label ranges within all BIER MPLS Encapsulation Sub-TLV inside the 223 same BIER Sub-TLV MUST NOT overlap. If the overlap is detected, the 224 advertising router MUST be treated as if it did not advertise a BIER 225 sub-TLV. 227 All advertised labels MUST be valid, otherwise the BIER sub-TLV MUST 228 be ignored. 230 2.3. Optional BIER Tree Type Sub-TLV 232 This Sub-TLV carries the information associated with the supported 233 BIER tree type for a sub-domain. This Sub-TLV is optional and its 234 absence has the same semantics as its presence with Tree Type value 0 235 (SPF). When Tree Type 0 is used, it is RECOMMENDED that this Sub-TLV 236 is omitted in order to reduce the space consumed in the parent TLV. 238 This Sub-TLV MAY occur no more than once in a BIER sub-TLV. If 239 multiple occurences of this Sub-TLV are present in a single BIER Sub- 240 TLV, the BIER sub-TLV MUST be ignored. 242 If the tree type (implied or explicitly advertised) does not match 243 the locally configured tree type associated with the matching sub- 244 domain, the BIER sub-TLV MUST be ignored. 246 0 1 2 3 247 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 1 248 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 249 | Type | Length | 250 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 251 | Tree Type | 252 +-+-+-+-+-+-+-+-+ 254 Type: TBD3. 256 Length: 1 octet. 258 Tree Type: 1 octet 260 2.4. Flooding scope of BIER Information 262 The flooding scope of the OSPF Extended Prefix Opaque LSA [RFC7684] 263 that is used for advertising the BIER Sub-TLV is set to area-local. 264 To allow BIER deployment in a multi-area environment, OSPF must 265 propagate BIER information between areas. The following procedure is 266 used in order to propagate BIER related information between areas: 268 When an OSPF Area Border Router (ABR) advertises a Type-3 Summary 269 LSA from an intra-area or inter-area prefix to all its attached 270 areas, it will also originate an Extended Prefix Opaque LSA, as 271 described in [RFC7684]. The flooding scope of the Extended Prefix 272 Opaque LSA type will be set to area-local. The route-type in the 273 OSPF Extended Prefix TLV is set to inter-area. When determining 274 whether a BIER Sub-TLV should be included in this LSA, an OSPF ABR 275 will: 277 - Examine its best path to the prefix in the source area and 278 find the advertising router associated with the best path to 279 that prefix. 281 - Determine if such advertising router advertised a BIER Sub- 282 TLV for the prefix. If yes, the ABR will copy the information 283 from such BIER MPLS Sub-TLV when advertising BIER MPLS Sub-TLV 284 to each attached area. 286 3. Security Considerations 288 Implementations must assure that malformed TLV and Sub-TLV 289 permutations do not result in errors which cause hard OSPF failures. 291 4. IANA Considerations 293 The document requests three new allocations from the OSPF Extended 294 Prefix sub-TLV registry as defined in [RFC7684]. 296 BIER Sub-TLV: TBD1 298 BIER MPLS Encapsulation Sub-TLV: TBD2 300 BIER Tree Type Sub-TLV: TBD3 302 5. Acknowledgments 304 The authors would like to thank Rajiv Asati, Christian Martin, Greg 305 Shepherd and Eric Rosen for their contribution. 307 6. Normative References 309 [I-D.ietf-bier-architecture] 310 Wijnands, I., Rosen, E., Dolganow, A., Przygienda, T., and 311 S. Aldrin, "Multicast using Bit Index Explicit 312 Replication", draft-ietf-bier-architecture-06 (work in 313 progress), April 2017. 315 [I-D.ietf-bier-mpls-encapsulation] 316 Wijnands, I., Rosen, E., Dolganow, A., Tantsura, J., 317 Aldrin, S., and I. Meilik, "Encapsulation for Bit Index 318 Explicit Replication in MPLS and non-MPLS Networks", 319 draft-ietf-bier-mpls-encapsulation-07 (work in progress), 320 June 2017. 322 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 323 Requirement Levels", BCP 14, RFC 2119, 324 DOI 10.17487/RFC2119, March 1997, 325 . 327 [RFC4915] Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P. 328 Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF", 329 RFC 4915, DOI 10.17487/RFC4915, June 2007, 330 . 332 [RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W., 333 Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute 334 Advertisement", RFC 7684, DOI 10.17487/RFC7684, November 335 2015, . 337 Authors' Addresses 339 Peter Psenak (editor) 340 Cisco 341 Apollo Business Center 342 Mlynske nivy 43 343 Bratislava 821 09 344 Slovakia 346 Email: ppsenak@cisco.com 348 Nagendra Kumar 349 Cisco 350 7200 Kit Creek Road 351 Research Triangle Park, NC 27709 352 US 354 Email: naikumar@cisco.com 356 IJsbrand Wijnands 357 Cisco 358 De Kleetlaan 6a 359 Diegem 1831 360 Belgium 362 Email: ice@cisco.com 364 Andrew Dolganow 365 Nokia 366 750 Chai Chee Rd 367 06-06 Viva Business Park 368 Singapore 469004 370 Email: andrew.dolganow@alcatel-lucent.com 371 Tony Przygienda 372 Juniper Networks, Inc. 373 10 Technology Park Drive 374 Westford, MA 01886 375 USA 377 Email: prz@juniper.net 379 Jeffrey Zhang 380 Juniper Networks, Inc. 381 10 Technology Park Drive 382 Westford, MA 01886 383 USA 385 Email: zzhang@juniper.net 387 Sam Aldrin 388 Google, Inc. 389 1600 Amphitheatre Parkway 390 Mountain View, CA 391 USA 393 Email: aldrin.ietf@gmail.com