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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Internet Engineering Task Force A. Przygienda 3 Internet-Draft Ericsson 4 Intended status: Standards Track L. Ginsberg 5 Expires: August 3, 2015 Cisco Systems 6 S. Aldrin 7 Huawei 8 J. Zhang 9 Juniper Networks, Inc. 10 January 30, 2015 12 BIER support via ISIS 13 draft-przygienda-bier-isis-ranges-02 15 Abstract 17 Specification of an ISIS extension to support BIER domains and sub- 18 domains. 20 Requirements Language 22 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 23 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 24 document are to be interpreted as described in RFC 2119 [RFC2119] . 26 Status of This Memo 28 This Internet-Draft is submitted in full conformance with the 29 provisions of BCP 78 and BCP 79. 31 Internet-Drafts are working documents of the Internet Engineering 32 Task Force (IETF). Note that other groups may also distribute 33 working documents as Internet-Drafts. The list of current Internet- 34 Drafts is at http://datatracker.ietf.org/drafts/current/. 36 Internet-Drafts are draft documents valid for a maximum of six months 37 and may be updated, replaced, or obsoleted by other documents at any 38 time. It is inappropriate to use Internet-Drafts as reference 39 material or to cite them other than as "work in progress." 41 This Internet-Draft will expire on August 3, 2015. 43 Copyright Notice 45 Copyright (c) 2015 IETF Trust and the persons identified as the 46 document authors. All rights reserved. 48 This document is subject to BCP 78 and the IETF Trust's Legal 49 Provisions Relating to IETF Documents 50 (http://trustee.ietf.org/license-info) in effect on the date of 51 publication of this document. Please review these documents 52 carefully, as they describe your rights and restrictions with respect 53 to this document. Code Components extracted from this document must 54 include Simplified BSD License text as described in Section 4.e of 55 the Trust Legal Provisions and are provided without warranty as 56 described in the Simplified BSD License. 58 Table of Contents 60 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 61 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 62 3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 63 4. Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . 4 64 4.1. BIER Domains and Sub-Domains . . . . . . . . . . . . . . 4 65 5. Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 4 66 5.1. Enabling a BIER Sub-Domain . . . . . . . . . . . . . . . 5 67 5.2. Multi Topology and Sub-Domain . . . . . . . . . . . . . . 5 68 5.3. Encapsulation . . . . . . . . . . . . . . . . . . . . . . 5 69 5.4. Tree Type . . . . . . . . . . . . . . . . . . . . . . . . 5 70 5.5. Label Advertisements for MPLS encapsulated BIER sub- 71 domains . . . . . . . . . . . . . . . . . . . . . . . . . 5 72 5.5.1. Special Consideration . . . . . . . . . . . . . . . . 6 73 5.6. BFR-id Advertisements . . . . . . . . . . . . . . . . . . 6 74 5.7. Flooding . . . . . . . . . . . . . . . . . . . . . . . . 6 75 5.8. Version . . . . . . . . . . . . . . . . . . . . . . . . . 6 76 6. Packet Formats . . . . . . . . . . . . . . . . . . . . . . . 7 77 6.1. BIER Info sub-TLV . . . . . . . . . . . . . . . . . . . . 7 78 6.2. BIER MPLS Encapsulation sub-sub-TLV . . . . . . . . . . . 8 79 6.3. Optional BIER sub-domain Tree Type sub-sub-TLV . . . . . 9 80 7. Security Considerations . . . . . . . . . . . . . . . . . . . 11 81 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11 82 9. Normative References . . . . . . . . . . . . . . . . . . . . 11 83 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12 85 1. Introduction 87 Bit Index Explicit Replication (BIER) 88 [I-D.draft-wijnands-bier-architecture-02] defines an architecture 89 where all intended multicast receivers are encoded as bitmask in the 90 Multicast packet header within different encapsulations such as 91 [I-D.draft-wijnands-mpls-bier-encapsulation-02]. A router that 92 receives such a packet will forward the packet based on the Bit 93 Position in the packet header towards the receiver(s), following a 94 precomputed tree for each of the bits in the packet. Each receiver 95 is represented by a unique bit in the bitmask. 97 This document presents necessary extensions to the currently deployed 98 ISIS for IP [RFC1195] protocol to support distribution of information 99 necessary for operation of BIER domains and sub-domains. This 100 document defines a new TLV to be advertised by every router 101 participating in BIER signaling. 103 2. Terminology 105 Some of the terminology specified in 106 [I-D.draft-wijnands-bier-architecture-02] is replicated here and 107 extended by necessary definitions: 109 BIER: Bit Index Explicit Replication (The overall architecture of 110 forwarding multicast using a Bit Position). 112 BIER-OL: BIER Overlay Signaling. (The method for the BFIR to learn 113 about BFER's). 115 BFR: Bit Forwarding Router (A router that participates in Bit Index 116 Multipoint Forwarding). A BFR is identified by a unique BFR- 117 prefix in a BIER domain. 119 BFIR: Bit Forwarding Ingress Router (The ingress border router that 120 inserts the BM into the packet). 122 BFER: Bit Forwarding Egress Router. A router that participates in 123 Bit Index Forwarding as leaf. Each BFER must be a BFR. Each BFER 124 must have a valid BFR-id assigned. 126 BFT: Bit Forwarding Tree used to reach all BFERs in a domain. 128 BIFT: Bit Index Forwarding Table. 130 BMS: Bit Mask Set. Set containing bit positions of all BFER 131 participating in a set. 133 BMP: Bit Mask Position, a given bit in a BMS. 135 Invalid BMP: Unassigned Bit Mask Position, consisting of all 0s. 137 IGP signalled BIER domain: A BIER underlay where the BIER 138 synchronization information is carried in IGP. Observe that a 139 multi-topology is NOT a separate BIER domain in IGP. 141 BIER sub-domain: A further distinction within a BIER domain 142 identified by its unique sub-domain identifier. A BIER sub-domain 143 can support multiple BitString Lengths. 145 BFR-id: An optional, unique identifier for a BFR within a BIER sub- 146 domain. 148 Invalid BFR-id: Unassigned BFR-id, consisting of all 0s. 150 3. IANA Considerations 152 This document adds the following new sub-TLVs to the registry of sub- 153 TLVs for TLVs 235, 237 [RFC5120] and TLVs 135,236 154 [RFC5305],[RFC5308]. 156 Value: 32 (suggested - to be assigned by IANA) 158 Name: BIER Info 160 4. Concepts 162 4.1. BIER Domains and Sub-Domains 164 An ISIS signalled BIER domain is aligned with the scope of 165 distribution of BFR-prefixes that identify the BFRs within ISIS. 166 ISIS acts in such a case as the according BIER underlay. 168 Within such a domain, ISIS extensions are capable of carrying BIER 169 information for multiple BIER sub-domains. Each sub-domain is 170 uniquely identified by its subdomain-id and each subdomain can reside 171 in any of the ISIS topologies [RFC5120]. The mapping of sub-domains 172 to topologies is a local decision of each BFR currently but is 173 advertised throughout the domain to ensure routing consistency. 175 Each BIER sub-domain has as its unique attributes the encapsulation 176 used and the type of tree it is using to forward BIER frames 177 (currently always SPF). Additionally, per supported bitstring length 178 in the sub-domain, each router will advertise the necessary label 179 ranges to support it. 181 This RFC introduces a sub-TLV in the extended reachability TLVs to 182 distribute such information about BIER sub-domains. To satisfy the 183 requirements for BIER prefixes per 184 [I-D.draft-wijnands-bier-architecture-02] additional information will 185 be carried in [I-D.draft-ginsberg-isis-prefix-attributes]. 187 5. Procedures 188 5.1. Enabling a BIER Sub-Domain 190 A given sub-domain with identifier BS with supported bitstring 191 lengths MLs in a multi-topology MT [RFC5120] is denoted further as 192 and is normally not advertised to preserve the scaling of 193 the protocol (i.e. ISIS carries no TLVs containing any of the 194 elements related to ) and is enabled by a first BIER sub-TLV 195 (Section 6.1) containing being advertised into the area. The 196 trigger itself is outside the scope of this RFC but can be for 197 example a VPN desiring to initiate a BIER sub-domain as MI-PMSI 198 [RFC6513] tree. It is outside the scope of this document to describe 199 what trigger for a router capable of participating in is used 200 to start the origination of the necessary information to join into 201 it. 203 5.2. Multi Topology and Sub-Domain 205 All routers in the flooding scope of the BIER TLVs MUST advertise a 206 sub-domain within the same multi-topology. A router discovering a 207 sub-domain advertised within a topology that is different from its 208 own MUST report a misconfiguration of a specific sub-domain. Each 209 router MUST compute BFTs for a sub-domain using only routers 210 advertising it in the same topology. 212 5.3. Encapsulation 214 All routers in the flooding scope of the BIER TLVs MUST advertise the 215 same encapsulation for a given . A router discovering 216 encapsulation advertised that is different from its own MUST report a 217 misconfiguration of a specific . Each router MUST compute 218 BFTs for using only routers having the same encapsulation as 219 its own advertised encapsulation in BIER sub-TLV for . 221 5.4. Tree Type 223 All routers in the flooding scope of the BIER TLVs MUST advertise the 224 same tree type for a given . In case of mismatch the behavior 225 is analogous to Section 5.3. 227 5.5. Label Advertisements for MPLS encapsulated BIER sub-domains 229 Each router MAY advertise within the BIER MPLS Encapsulation sub-sub- 230 TLV (Section 6.2) of a BIER Info sub-TLV (Section 6.1, denoted as 231 TLV) for for every supported bitstring length a valid 232 starting label value and a non-zero range length. It MUST advertise 233 at least one valid label value and a non-zero range length for the 234 required bitstring lengths per 235 [I-D.draft-wijnands-bier-architecture-02] in case it has computed 236 itself as being on the BFT rooted at any of the BFRs with valid BFR- 237 ids (except itself if it does NOT have a valid BFR-id) participating 238 in . 240 A router MAY decide to not advertise the BIER Info sub-TLV 241 (Section 6.1) for if it does not want to participate in the 242 sub-domain due to resource constraints, label space optimization, 243 administrative configuration or any other reasons. 245 5.5.1. Special Consideration 247 A router MUST advertise for each bitstring length it supports in 248 a label range size that guarantees to cover the maximum BFR- 249 id injected into (which implies a certain maximum set id per 250 bitstring length as described in 251 [I-D.draft-wijnands-bier-architecture-02]). Any router that violates 252 this condition MUST be excluded from BIER BFTs for . 254 5.6. BFR-id Advertisements 256 Each BFER MAY advertise with its TLV the BFR-id that it has 257 administratively chosen. 259 If a router discovers that two BFRs it can reach advertise the same 260 value for BFR-id for , it MUST report a misconfiguration and 261 disregard those routers for all BIER calculations and procedures for 262 to align with [I-D.draft-wijnands-bier-architecture-02]. It 263 is worth observing that based on this procedure routers with 264 colliding BFR-id assignments in MAY still act as BFIRs in 265 but will be never able to receive traffic from other BFRs in 266 . 268 5.7. Flooding 270 BIER domain information SHOULD change and force flooding 271 infrequently. Especially, the router SHOULD make every possible 272 attempt to bundle all the changes necessary to sub-domains and ranges 273 advertised with those into least possible updates. 275 5.8. Version 277 This RFC specifies Version 0 of the BIER extension encodings. Packet 278 encoding supports introduction of future, higher versions with e.g. 279 new sub-sub-TLVs or redefining reserved bits that can maintain the 280 compatiblity to Version 0 or choose to indicate that the 281 compatibility cannot be maintained anymore (changes that cannot work 282 with the provided encoding would necessitate obviously introduction 283 of completely new sub-TLV for BIER). 285 This kind of 'versioning' allows to introduce e.g. backwards- 286 compatible automatic assignment of unique BFR-ids within sub-domains 287 or addition of optional sub-sub-TLVs that can be ignored by version 0 288 BIER routers without the danger of incompatiblity. 290 This is a quite common technique in software development today to 291 maintain and extend backwards compatible APIs. 293 6. Packet Formats 295 All ISIS BIER information is carried within the TLVs 235, 237 296 [RFC5120] and TLVs 135,236 [RFC5305], [RFC5308]. 298 6.1. BIER Info sub-TLV 300 This sub-TLV carries the information for the BIER sub-domains that 301 the router participates in as BFR. It can repeat multiple times for 302 different sub-domain combinations. 304 The sub-TLV carries a single combination followed by optional 305 sub-sub-TLVs specified within its context such as e.g. BIER MPLS 306 Encapsulation per Section 6.2. 308 On violation of any of the following conditions, the receiving router 309 SHOULD signal a misconfiguration condition. Further results are 310 unspecified unless described in the according section of this RFC: 312 o The subdomain-id MUST be included only within a single topology. 314 0 1 2 3 315 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 1 316 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 317 | Type | Length | 318 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 319 |Ver|C| Reserved| subdomain-id | BFR-id | 320 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 322 Type: as indicated in IANA section. 324 Length: 1 octet. 326 Version: Version of the BIER TLV advertised, must be 0 on 327 transmission by router implementing this RFC. Behavior on 328 reception depends on the 'C' bit. 2 bits 330 C-BIT: Compatibility bit indicating that the TLV can be interpreted 331 by routers implementing lower than the advertised version. Router 332 implementing this version of the RFC MUST set it to 1. On 333 reception, IF the version of the protocol is higher than 0 AND the 334 bit is set (i.e. its value is 1), the TLV MUST be processed 335 normally, IF the bit is clear (i.e. its value is 0), the TLV MUST 336 be ignored for further processing completely independent of the 337 advertised version. When processing this sub-TLV with 338 compatibility bit set, all sub-sub-TLV of unknown type MUST and 339 CAN be safely ignored. 1 bit 341 Reserved: reserved, must be 0 on transmission, ignored on reception. 342 May be used in future versions. 5 bits 344 subdomain-id: Unique value identifying the BIER sub-domain. 1 octet 346 BFR-id: A 2 octet field encoding the BFR-id, as documented in 347 [I-D.draft-wijnands-bier-architecture-02]. If set to the invalid 348 BFR-id advertising router is not owning a BFR-id in the sub- 349 domain. 351 6.2. BIER MPLS Encapsulation sub-sub-TLV 353 This sub-sub-TLV carries the information for the BIER MPLS 354 encapsulation and the necessary label ranges per bitstring length for 355 a certain and is carried within the BIER Info sub-TLV 356 (Section 6.1) that the router participates in as BFR. 358 On violation of any of the following conditions, the receiving router 359 SHOULD signal a misconfiguration condition. Further results are 360 unspecified: 362 o The sub-sub-TLV MUST be included once AND ONLY once within the 363 sub-TLV. 365 o Label ranges within the sub-sub-TLV MUST NOT overlap. A receiving 366 BFR MAY additionally check whether any of the ranges in all the 367 sub-sub-TLVs advertised by another BFR overlap and apply the same 368 treatement on violations. 370 o Bitstring lengths within the sub-sub-TLV MUST NOT repeat. 372 o The sub-sub-TLV MUST include the required bitstring lengths per 373 [I-D.draft-wijnands-bier-architecture-02]. 375 o All label range sizes MUST be greater than 0. 377 o All labels MUST represent valid label values. 379 0 1 2 3 380 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 1 381 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 382 | Type | Length | 383 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ <-+ 384 | Lbl Range Size|BS Len | Label | | 385 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 386 ~~ (number repetitions derived from TLV length) ~~ ~~~ 387 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 388 | Lbl Range Size|BS Len | Label | | 389 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ <-+ 391 Type: value of 0 indicating MPLS encapsulation. 393 Length: 1 octet. 395 Local BitString Length (BS Len): Bitstring length for the label 396 range that this router is advertising per 397 [I-D.draft-wijnands-mpls-bier-encapsulation-02]. 4 bits. 399 Label Range Size: Number of labels in the range used on 400 encapsulation for this BIER sub-domain for this bitstring length, 401 1 octet. This MUST never be advertised as 0 (zero) and otherwise, 402 this sub-sub-TLV must be treated as if not present for BFT 403 calculations and a misconfiguration SHOULD be reported by the 404 receiving router. 406 Label: First label of the range used on encapsulation for this BIER 407 sub-domain for this bitstring length, 20 bits. The label is used 408 for example by [I-D.draft-wijnands-mpls-bier-encapsulation-02] to 409 forward traffic to sets of BFERs. 411 6.3. Optional BIER sub-domain Tree Type sub-sub-TLV 413 This sub-sub-TLV carries the information of the BIER tree type for a 414 certain . It is carried within the BIER Info sub-TLV 415 (Section 6.1) that the router participates in as BFR. This sub-sub- 416 TLV is optional and its absence indicates the same as its presence 417 with Tree Type value 0 (SPF). BIER implementation following this 418 version of the RFC SHOULD NOT advertise this TLV. 420 On violation of any of the following conditions, the receiving router 421 implementing this RFC SHOULD signal a misconfiguration condition. 422 Further results are unspecified unless described further: 424 o The sub-sub-TLV MUST be included once AND ONLY once. 426 o The advertised BIER TLV version is 0 and the value of Tree Type 427 MUST be 0 (SPF). 429 0 1 2 3 430 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 1 431 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 432 | Type | Length | 433 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 434 | Tree Type | 435 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 436 | Tree Type specific opaque data| 437 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 438 ~~ up to TLV Length ~~ 439 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 440 | Tree Type specific opaque data| 441 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 443 Type: value of 1 indicating BIER Tree Type. 445 Length: 1 octet. 447 Tree Type: The only supported value today is 0 and indicates that 448 BIER uses normal SPF computed reachability to construct BIFT. 449 BIER implementation following this RFC MUST ignore the node for 450 purposes of the sub-domain if this field has any value 451 except 0. 453 Tree type specific opaque data: Opaque data up to the length of the 454 TLV carrying tree type specific parameters. For Tree Type 0 (SPF) 455 no such data is included and therefore TLV Length is 1. 457 7. Security Considerations 459 Implementations must assure that malformed TLV and Sub-TLV 460 permutations do not result in errors which cause hard protocol 461 failures. 463 8. Acknowledgements 465 The RFC is aligned with the [I-D.draft-psenak-ospf-bier-extension-01] 466 draft as far as the protocol mechanisms overlap. 468 Many thanks for comments from (in no particular order) Hannes 469 Gredler, Ijsbrand Wijnands and Peter Psenak. 471 9. Normative References 473 [I-D.draft-ginsberg-isis-prefix-attributes] 474 Ginsberg et al., U., "IS-IS Prefix Attributes for Extended 475 IP and IPv6 Reachability", internet-draft draft-ginsberg- 476 isis-prefix-attributes-00.txt, October 2014. 478 [I-D.draft-psenak-ospf-bier-extension-01] 479 Psenak, P. and IJ. Wijnands, "OSPF Extension for Bit Index 480 Explicit Replication", internet-draft draft-ietf-ospf- 481 prefix-link-attr-01.txt, October 2014. 483 [I-D.draft-wijnands-bier-architecture-02] 484 Wijnands, IJ., "Stateless Multicast using Bit Index 485 Explicit Replication Architecture", internet-draft draft- 486 wijnands-bier-architecture-02.txt, February 2014. 488 [I-D.draft-wijnands-mpls-bier-encapsulation-02] 489 Wijnands et al., IJ., "Bit Index Explicit Replication 490 using MPLS encapsulation", internet-draft draft-wijnands- 491 mpls-bier-encapsulation-02.txt, February 2014. 493 [RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and 494 dual environments", RFC 1195, December 1990. 496 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 497 Requirement Levels", BCP 14, RFC 2119, March 1997. 499 [RFC4971] Vasseur, JP., Shen, N., and R. Aggarwal, "Intermediate 500 System to Intermediate System (IS-IS) Extensions for 501 Advertising Router Information", RFC 4971, July 2007. 503 [RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi 504 Topology (MT) Routing in Intermediate System to 505 Intermediate Systems (IS-ISs)", RFC 5120, February 2008. 507 [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic 508 Engineering", RFC 5305, October 2008. 510 [RFC5308] Hopps, C., "Routing IPv6 with IS-IS", RFC 5308, October 511 2008. 513 [RFC6513] Rosen, E. and R. Aggarwal, "Multicast in MPLS/BGP IP 514 VPNs", RFC 6513, February 2012. 516 Authors' Addresses 518 Tony Przygienda 519 Ericsson 520 300 Holger Way 521 San Jose, CA 95134 522 USA 524 Email: antoni.przygienda@ericsson.com 526 Les Ginsberg 527 Cisco Systems 528 510 McCarthy Blvd. 529 Milpitas, CA 95035 530 USA 532 Email: ginsberg@cisco.com 534 Sam Aldrin 535 Huawei 536 2330 Central Expressway 537 Santa Clara, CA 95051 538 USA 540 Email: aldrin.ietf@gmail.com 541 Jeffrey (Zhaohui) Zhang 542 Juniper Networks, Inc. 543 10 Technology Park Drive 544 Westford, MA 01886 545 USA 547 Email: zzhang@juniper.net