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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) -- Looks like a reference, but probably isn't: '0' on line 556 -- Looks like a reference, but probably isn't: '1' on line 538 == Unused Reference: 'RFC4443' is defined on line 426, but no explicit reference was found in the text Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 6man R. Bonica 3 Internet-Draft Juniper Networks 4 Intended status: Standards Track Y. Kamite 5 Expires: November 14, 2020 NTT Communications Corporation 6 T. Niwa 7 KDDI 8 A. Alston 9 Liquid Telecom 10 L. Jalil 11 Verizon 12 May 13, 2020 14 The IPv6 Compact Routing Header (CRH) 15 draft-bonica-6man-comp-rtg-hdr-18 17 Abstract 19 This document defines two new Routing header types. Collectively, 20 they are called the Compact Routing Headers (CRH). Individually, 21 they are called CRH-16 and CRH-32. 23 Status of This Memo 25 This Internet-Draft is submitted in full conformance with the 26 provisions of BCP 78 and BCP 79. 28 Internet-Drafts are working documents of the Internet Engineering 29 Task Force (IETF). Note that other groups may also distribute 30 working documents as Internet-Drafts. The list of current Internet- 31 Drafts is at https://datatracker.ietf.org/drafts/current/. 33 Internet-Drafts are draft documents valid for a maximum of six months 34 and may be updated, replaced, or obsoleted by other documents at any 35 time. It is inappropriate to use Internet-Drafts as reference 36 material or to cite them other than as "work in progress." 38 This Internet-Draft will expire on November 14, 2020. 40 Copyright Notice 42 Copyright (c) 2020 IETF Trust and the persons identified as the 43 document authors. All rights reserved. 45 This document is subject to BCP 78 and the IETF Trust's Legal 46 Provisions Relating to IETF Documents 47 (https://trustee.ietf.org/license-info) in effect on the date of 48 publication of this document. Please review these documents 49 carefully, as they describe your rights and restrictions with respect 50 to this document. Code Components extracted from this document must 51 include Simplified BSD License text as described in Section 4.e of 52 the Trust Legal Provisions and are provided without warranty as 53 described in the Simplified BSD License. 55 Table of Contents 57 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 58 2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3 59 3. The Compressed Routing Headers (CRH) . . . . . . . . . . . . 3 60 4. The CRH Forwarding Information Base (CRH-FIB) . . . . . . . 5 61 5. Processing Rules . . . . . . . . . . . . . . . . . . . . . . 5 62 5.1. Computing Minimum CRH Length . . . . . . . . . . . . . . 6 63 6. Mutability . . . . . . . . . . . . . . . . . . . . . . . . . 7 64 7. Applications And SIDs . . . . . . . . . . . . . . . . . . . . 7 65 8. Management Considerations . . . . . . . . . . . . . . . . . . 8 66 9. Security Considerations . . . . . . . . . . . . . . . . . . . 8 67 10. Implementation and Deployment Status . . . . . . . . . . . . 8 68 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 69 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9 70 13. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 9 71 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 72 14.1. Normative References . . . . . . . . . . . . . . . . . . 10 73 14.2. Informative References . . . . . . . . . . . . . . . . . 10 74 Appendix A. CRH Processing Examples . . . . . . . . . . . . . . 11 75 A.1. The SID List Contains One Entry For Each Segment In The 76 Path . . . . . . . . . . . . . . . . . . . . . . . . . . 12 77 A.2. The SID List Omits The First Entry In The Path . . . . . 12 78 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13 80 1. Introduction 82 IPv6 [RFC8200] source nodes use Routing headers to specify the path 83 that a packet takes to its destination. The IETF has defined several 84 Routing header types [IANA-RH]. This document defines two new 85 Routing header types. Collectively, they are called the Compact 86 Routing Headers (CRH). Individually, they are called CRH-16 and CRH- 87 32. 89 The CRH allows IPv6 source nodes to specify the path that a packet 90 takes to its destination. The CRH: 92 o Can be encoded in relatively few bytes. 94 o Is designed to operate within a network domain. (See Section 9). 96 The following are reasons for encoding the CRH in as few bytes as 97 possible: 99 o Many ASIC-based forwarders copy all headers from buffer memory to 100 on-chip memory. As header sizes increase, so does the cost of 101 this copy. 103 o Because Path MTU Discovery (PMTUD) [RFC8201] is not entirely 104 reliable, many IPv6 hosts refrain from sending packets larger than 105 the IPv6 minimum link MTU (i.e., 1280 bytes). When packets are 106 small, the overhead imposed by large Routing Headers is excessive. 108 Section 9 of this document addresses security considerations. 110 2. Requirements Language 112 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 113 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 114 "OPTIONAL" in this document are to be interpreted as described in BCP 115 14 [RFC2119] [RFC8174] when, and only when, they appear in all 116 capitals, as shown here. 118 3. The Compressed Routing Headers (CRH) 120 Both CRH versions (i.e., CRH-16 and CRH-32) contain the following 121 fields: 123 o Next Header - Defined in [RFC8200]. 125 o Hdr Ext Len - Defined in [RFC8200]. 127 o Routing Type - Defined in [RFC8200]. Value TBD by IANA. (For 128 CRH-16, the suggested value is 5. For CRH-32, the suggested value 129 is 6.) 131 o Segments Left - Defined in [RFC8200]. 133 o Type-specific Data - Described in [RFC8200]. 135 In the CRH, the Type-specific data field contains a list of Segment 136 Identifiers (SIDs). Each SID represents both of the following: 138 o A segment of the path that the packet takes to its destination. 140 o An entry in the CRH Forwarding Information Base (CRH-FIB) 141 (Section 4). 143 SIDs are listed in reverse order. So, the first SID in the list 144 represents the final segment in the path. Because segments are 145 listed in reverse order, the Segments Left field can be used as an 146 index into the SID list. In this document, the "current SID" is the 147 SID list entry referenced by the Segments Left field. 149 The first segment in the path can be omitted from the list. See 150 (Appendix A) for examples. 152 In the CRH-16 (Figure 1), each SID is encoded in 16-bits. In the 153 CRH-32 (Figure 2), each SID is encoded in 32-bits. 155 In all cases, the CRH MUST end on a 64-bit boundary. So, the Type- 156 specific data field MUST be padded with zeros if the CRH would 157 otherwise not end on a 64-bit boundary. 159 0 1 2 3 160 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 1 161 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 162 | Next Header | Hdr Ext Len | Routing Type | Segments Left | 163 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 164 | SID[0] | SID[1] | 165 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-| 166 | ......... 167 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 169 Figure 1: CRH-16 171 0 1 2 3 172 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 1 173 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 174 | Next Header | Hdr Ext Len | Routing Type | Segments Left | 175 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 176 + SID[0] + 177 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 178 + SID[1] + 179 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 180 // // 181 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 182 + SID[n] + 183 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 185 Figure 2: CRH-32 187 4. The CRH Forwarding Information Base (CRH-FIB) 189 Each SID identifies a CRH-FIB entry. 191 Each CRH-FIB entry contains: 193 o A IPv6 address. 195 o A forwarding method. 197 o Method-specific parameters (optional). 199 The IPv6 address represents an interface on the next segment 200 endpoint. It MUST NOT be a link-local address. While the IPv6 201 address represents an interface on the next segment endpoint, it does 202 not necessarily represent the interface through which the packet will 203 arrive at the next segment endpoint. 205 The forwarding method specifies how the processing node will forward 206 the packet to the next segment endpoint. The following are examples: 208 o Forward the packet to the next-hop along the least-cost path to 209 the next segment endpoint. 211 o Forward the packet through a specified interface to the next 212 segment endpoint. 214 Some forwarding methods require method-specific parameters. For 215 example, a forwarding method might require a parameter that 216 identifies the interface through which the packet should be 217 forwarded. 219 The CRH-FIB can be populated: 221 o By an operator, using a Command Line Interface (CLI). 223 o By a controller, using the Path Computation Element (PCE) 224 Communication Protocol (PCEP) [RFC5440] or the Network 225 Configuration Protocol (NETCONF) [RFC6241]. 227 o By a distributed routing protocol [ISO10589-Second-Edition], 228 [RFC5340], [RFC4271]. 230 5. Processing Rules 232 The following rules describe CRH processing: 234 o If Segments Left equals 0, skip over the CRH and process the next 235 header in the packet. 237 o If Hdr Ext Len indicates that the CRH is larger than the 238 implementation can process, discard the packet and send an ICMPv6 239 Parameter Problem, Code 0, message to the Source Address, pointing 240 to the Hdr Ext Len field. 242 o Compute L, the minimum CRH length (See (Section 5.1)). 244 o If L is greater than Hdr Ext Len, discard the packet and send an 245 ICMPv6 Parameter Problem, Code 0, message to the Source Address, 246 pointing to the Segments Left field. 248 o Decrement Segments Left. 250 o Search for the current SID in the CRH-FIB. In this document, the 251 "current SID" is the SID list entry referenced by the Segments 252 Left field. 254 o If the search does not return a CRH-FIB entry, discard the packet 255 and send an ICMPv6 Parameter Problem, Code 0, message to the 256 Source Address, pointing to the current SID. 258 o If Segments Left is greater than 0 and the CRH-FIB entry contains 259 a multicast address, discard the packet and send an ICMPv6 260 Parameter Problem, Code 0, message to the Source Address, pointing 261 to the current SID. 263 o Copy the IPv6 address from the CRH-FIB entry to the Destination 264 Address field in the IPv6 header. 266 o Decrement the IPv6 Hop Limit. 268 o Resubmit the packet to the IPv6 module for transmission to the new 269 destination, ensuring that it executes the forwarding method 270 specified by the CRH-FIB entry. 272 5.1. Computing Minimum CRH Length 274 The algorithm described in this section accepts the following CRH 275 fields as its input parameters: 277 o Routing Type (i.e., CRH-16 or CRH-32). 279 o Segments Left. 281 It yields L, the minimum CRH length. The minimum CRH length is 282 measured in 8-octet units, not including the first 8 octets. 284 286 switch(Routing Type) { 287 case CRH-16: 288 if (Segments Left <= 2) 289 return(0) 290 sidsBeyondFirstWord = Segments Left - 2; 291 sidPerWord = 4; 292 case CRH-32: 293 if (Segments Left <= 1) 294 return(0) 295 sidsBeyondFirstWord = Segments Left - 1; 296 sidsPerWord = 2; 297 case default: 298 return(0xFF); 299 } 301 words = sidsBeyondFirstWord div sidsPerWord; 302 if (sidsBeyondFirstWord mod sidsPerWord) 303 words++; 305 return(words) 307 309 6. Mutability 311 In the CRH, the Segments Left field is mutable. All remaining fields 312 are immutable. 314 7. Applications And SIDs 316 A CRH contains one or more SIDs. Each SID is processed by exactly 317 one node. 319 Therefore, a SID is not required to have domain-wide significance. 320 Applications can: 322 o Allocate SIDs so that they have domain-wide significance. 324 o Allocate SIDs so that they have node-local significance. 326 8. Management Considerations 328 PING and TRACEROUTE [RFC2151] both operate correctly in the presence 329 of the CRH. 331 9. Security Considerations 333 Networks that process the CRH MUST NOT accept packets containing the 334 CRH from untrusted sources. Their border routers SHOULD discard 335 packets that satisfy the following criteria: 337 o The packet contains a CRH 339 o The Segments Left field in the CRH has a value greater than 0 341 o The Destination Address field in the IPv6 header represents an 342 interface that resides inside of the network. 344 Many border routers cannot filter packets based upon the Segments 345 Left value. These border routers MAY discard packets that satisfy 346 the following criteria: 348 o The packet contains a CRH 350 o The Destination Address field in the IPv6 header represents an 351 interface that resides inside of the network. 353 10. Implementation and Deployment Status 355 Juniper Networks has produced experimental implementations of the CRH 356 on: 358 o A LINUX-based software platform 360 o The MX-series (ASIC-based) router 362 Liquid Telecom has deployed the CRH, on a limited basis, in their 363 network. Other experimental deployments are in progress. 365 11. IANA Considerations 367 SID values 0-15 are reserved for future use. They may be assigned by 368 IANA, based on IETF Consensus. IANA is requested to establish a 369 "Registry of SRm6 Reserved SIDs". Values 0-15 are reserved for 370 future use. 372 IANA is requested to make the following entries in the Internet 373 Protocol Version 6 (IPv6) Parameters "Routing Type" registry 374 [IANA-RH]: 376 Suggested 377 Value Description Reference 378 --------------------------------------------------------------------- 379 5 Compact Routing Header (16-bit) (CRH-16) This document 380 6 Compact Routing Header (32-bit) (CRH-32) This document 382 12. Acknowledgements 384 Thanks to Dr. Vanessa Ameen, Fernando Gont, Naveen Kottapalli, Joel 385 Halpern, Tony Li, Gerald Schmidt, Nancy Shaw, and Chandra Venkatraman 386 for their contributions to this document. 388 13. Contributors 390 Daniam Henriques 392 Liquid Telecom 394 Johannesburg, South Africa 396 Email: daniam.henriques@liquidtelecom.com 398 Gang Chen 400 Baidu 402 No.10 Xibeiwang East Road Haidian District 404 Beijing 100193 P.R. China 406 Email: phdgang@gmail.com 408 Yifeng Zhou 410 ByteDance 412 Building 1, AVIC Plaza, 43 N 3rd Ring W Rd Haidian District 414 Beijing 100000 P.R. China 415 Email: yifeng.zhou@bytedance.com 417 14. References 419 14.1. Normative References 421 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 422 Requirement Levels", BCP 14, RFC 2119, 423 DOI 10.17487/RFC2119, March 1997, 424 . 426 [RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet 427 Control Message Protocol (ICMPv6) for the Internet 428 Protocol Version 6 (IPv6) Specification", STD 89, 429 RFC 4443, DOI 10.17487/RFC4443, March 2006, 430 . 432 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 433 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 434 May 2017, . 436 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 437 (IPv6) Specification", STD 86, RFC 8200, 438 DOI 10.17487/RFC8200, July 2017, 439 . 441 [RFC8201] McCann, J., Deering, S., Mogul, J., and R. Hinden, Ed., 442 "Path MTU Discovery for IP version 6", STD 87, RFC 8201, 443 DOI 10.17487/RFC8201, July 2017, 444 . 446 14.2. Informative References 448 [IANA-RH] IANA, "Routing Headers", 449 . 452 [ISO10589-Second-Edition] 453 International Organization for Standardization, 454 ""Intermediate system to Intermediate system intra-domain 455 routeing information exchange protocol for use in 456 conjunction with the protocol for providing the 457 connectionless-mode Network Service (ISO 8473)", ISO/IEC 458 10589:2002, Second Edition,", November 2001. 460 [RFC2151] Kessler, G. and S. Shepard, "A Primer On Internet and TCP/ 461 IP Tools and Utilities", FYI 30, RFC 2151, 462 DOI 10.17487/RFC2151, June 1997, 463 . 465 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 466 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 467 DOI 10.17487/RFC4271, January 2006, 468 . 470 [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF 471 for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, 472 . 474 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 475 Element (PCE) Communication Protocol (PCEP)", RFC 5440, 476 DOI 10.17487/RFC5440, March 2009, 477 . 479 [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., 480 and A. Bierman, Ed., "Network Configuration Protocol 481 (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011, 482 . 484 Appendix A. CRH Processing Examples 486 This appendix demonstrates CRH processing in the following scenarios: 488 o The SID list contains one entry for each segment in the path 489 (Appendix A.1). 491 o The SID list omits the first entry in the path (Appendix A.2). 493 ----------- ----------- ----------- 494 |Node: S | |Node: I1 | |Node: I2 | 495 |Loopback: |---------------|Loopback: |---------------|Loopback: | 496 |2001:db8::a| |2001:db8::1| |2001:db8::2| 497 ----------- ----------- ----------- 498 | | 499 | ----------- | 500 | |Node: D | | 501 ---------------------|Loopback: |--------------------- 502 |2001:db8::b| 503 ----------- 505 Figure 3: Reference Topology 507 Figure 3 provides a reference topology that is used in all examples. 509 +-----+--------------+-------------------+ 510 | SID | IPv6 Address | Forwarding Method | 511 +-----+--------------+-------------------+ 512 | 2 | 2001:db8::2 | Least-cost path | 513 | 11 | 2001:db8::b | Least-cost path | 514 +-----+--------------+-------------------+ 516 Table 1: Node SIDs 518 Table 1 describes two entries that appear in each node's CRH-FIB. 520 A.1. The SID List Contains One Entry For Each Segment In The Path 522 In this example, Node S sends a packet to Node D, via I2. In this 523 example, I2 appears in the CRH segment list. 525 +-------------------------------------+-------------------+ 526 | As the packet travels from S to I2: | | 527 +-------------------------------------+-------------------+ 528 | Source Address = 2001:db8::a | Segments Left = 1 | 529 | Destination Address = 2001:db8::2 | SID[0] = 11 | 530 | | SID[1] = 2 | 531 +-------------------------------------+-------------------+ 533 +-------------------------------------+-------------------+ 534 | As the packet travels from I2 to D: | | 535 +-------------------------------------+-------------------+ 536 | Source Address = 2001:db8::a | Segments Left = 0 | 537 | Destination Address = 2001:db8::b | SID[0] = 11 | 538 | | SID[1] = 2 | 539 +-------------------------------------+-------------------+ 541 A.2. The SID List Omits The First Entry In The Path 543 In this example, Node S sends a packet to Node D, via I2. In this 544 example, I2 does not appear in the CRH segment list. 546 +-------------------------------------+-------------------+ 547 | As the packet travels from S to I2: | | 548 +-------------------------------------+-------------------+ 549 | Source Address = 2001:db8::a | Segments Left = 1 | 550 | Destination Address = 2001:db8::2 | SID[0] = 11 | 551 +-------------------------------------+-------------------+ 552 +-------------------------------------+-------------------+ 553 | As the packet travels from I2 to D: | | 554 +-------------------------------------+-------------------+ 555 | Source Address = 2001:db8::a | Segments Left = 0 | 556 | Destination Address = 2001:db8::b | SID[0] = 11 | 557 +-------------------------------------+-------------------+ 559 Authors' Addresses 561 Ron Bonica 562 Juniper Networks 563 2251 Corporate Park Drive 564 Herndon, Virginia 20171 565 USA 567 Email: rbonica@juniper.net 569 Yuji Kamite 570 NTT Communications Corporation 571 3-4-1 Shibaura, Minato-ku 572 Tokyo 108-8118 573 Japan 575 Email: y.kamite@ntt.com 577 Tomonobu Niwa 578 KDDI 579 3-22-7, Yoyogi, Shibuya-ku 580 Tokyo 151-0053 581 Japan 583 Email: to-niwa@kddi.com 585 Andrew Alston 586 Liquid Telecom 587 Nairobi 588 Kenya 590 Email: Andrew.Alston@liquidtelecom.com 591 Luay Jalil 592 Verizon 593 Richardson, Texas 594 USA 596 Email: luay.jalil@one.verizon.com