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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 567 -- Looks like a reference, but probably isn't: '1' on line 548 == Unused Reference: 'RFC4443' is defined on line 436, 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 15, 2020 NTT Communications Corporation 6 T. Niwa 7 KDDI 8 A. Alston 9 Liquid Telecom 10 L. Jalil 11 Verizon 12 May 14, 2020 14 The IPv6 Compact Routing Header (CRH) 15 draft-bonica-6man-comp-rtg-hdr-20 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 15, 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 . . . . . 13 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 2. Requirements Language 110 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 111 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 112 "OPTIONAL" in this document are to be interpreted as described in BCP 113 14 [RFC2119] [RFC8174] when, and only when, they appear in all 114 capitals, as shown here. 116 3. The Compressed Routing Headers (CRH) 118 Both CRH versions (i.e., CRH-16 and CRH-32) contain the following 119 fields: 121 o Next Header - Defined in [RFC8200]. 123 o Hdr Ext Len - Defined in [RFC8200]. 125 o Routing Type - Defined in [RFC8200]. Value TBD by IANA. (For 126 CRH-16, the suggested value is 5. For CRH-32, the suggested value 127 is 6.) 129 o Segments Left - Defined in [RFC8200]. 131 o Type-specific Data - Described in [RFC8200]. 133 In the CRH, the Type-specific data field contains a list of Segment 134 Identifiers (SIDs). Each SID represents both of the following: 136 o A segment of the path that the packet takes to its destination. 138 o An entry in the CRH Forwarding Information Base (CRH-FIB) 139 (Section 4). 141 SIDs are listed in reverse order. So, the first SID in the list 142 represents the final segment in the path. Because segments are 143 listed in reverse order, the Segments Left field can be used as an 144 index into the SID list. In this document, the "current SID" is the 145 SID list entry referenced by the Segments Left field. 147 The first segment in the path can be omitted from the list. See 148 (Appendix A) for examples. 150 In the CRH-16 (Figure 1), each SID is encoded in 16-bits. In the 151 CRH-32 (Figure 2), each SID is encoded in 32-bits. 153 In all cases, the CRH MUST end on a 64-bit boundary. So, the Type- 154 specific data field MUST be padded with zeros if the CRH would 155 otherwise not end on a 64-bit boundary. 157 0 1 2 3 158 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 1 159 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 160 | Next Header | Hdr Ext Len | Routing Type | Segments Left | 161 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 162 | SID[0] | SID[1] | 163 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-| 164 | ......... 165 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 167 Figure 1: CRH-16 169 0 1 2 3 170 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 1 171 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 172 | Next Header | Hdr Ext Len | Routing Type | Segments Left | 173 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 174 + SID[0] + 175 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 176 + SID[1] + 177 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 178 // // 179 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 180 + SID[n] + 181 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 183 Figure 2: CRH-32 185 4. The CRH Forwarding Information Base (CRH-FIB) 187 Each SID identifies a CRH-FIB entry. 189 Each CRH-FIB entry contains: 191 o A IPv6 address. 193 o A forwarding method. 195 o Method-specific parameters (optional). 197 The IPv6 address represents an interface on the next segment 198 endpoint. It MUST NOT be a link-local address. While the IPv6 199 address represents an interface on the next segment endpoint, it does 200 not necessarily represent the interface through which the packet will 201 arrive at the next segment endpoint. 203 The forwarding method specifies how the processing node will forward 204 the packet to the next segment endpoint. The following are examples: 206 o Forward the packet to the next-hop along the least-cost path to 207 the next segment endpoint. 209 o Forward the packet through a specified interface to the next 210 segment endpoint. 212 Some forwarding methods require method-specific parameters. For 213 example, a forwarding method might require a parameter that 214 identifies the interface through which the packet should be 215 forwarded. 217 The CRH-FIB can be populated: 219 o By an operator, using a Command Line Interface (CLI). 221 o By a controller, using the Path Computation Element (PCE) 222 Communication Protocol (PCEP) [RFC5440] or the Network 223 Configuration Protocol (NETCONF) [RFC6241]. 225 o By a distributed routing protocol [ISO10589-Second-Edition], 226 [RFC5340], [RFC4271]. 228 5. Processing Rules 230 The following rules describe CRH processing: 232 o If Segments Left equals 0, skip over the CRH and process the next 233 header in the packet. 235 o If Hdr Ext Len indicates that the CRH is larger than the 236 implementation can process, discard the packet and send an ICMPv6 237 Parameter Problem, Code 0, message to the Source Address, pointing 238 to the Hdr Ext Len field. 240 o Compute L, the minimum CRH length (See (Section 5.1)). 242 o If L is greater than Hdr Ext Len, discard the packet and send an 243 ICMPv6 Parameter Problem, Code 0, message to the Source Address, 244 pointing to the Segments Left field. 246 o Decrement Segments Left. 248 o Search for the current SID in the CRH-FIB. In this document, the 249 "current SID" is the SID list entry referenced by the Segments 250 Left field. 252 o If the search does not return a CRH-FIB entry, discard the packet 253 and send an ICMPv6 Parameter Problem, Code 0, message to the 254 Source Address, pointing to the current SID. 256 o If Segments Left is greater than 0 and the CRH-FIB entry contains 257 a multicast address, discard the packet and send an ICMPv6 258 Parameter Problem, Code 0, message to the Source Address, pointing 259 to the current SID. 261 o Copy the IPv6 address from the CRH-FIB entry to the Destination 262 Address field in the IPv6 header. 264 o Decrement the IPv6 Hop Limit. 266 o Submit the packet and optional parameters to the IPv6 module. 267 Optional parameters are derived from the CRH-SID. See NOTE. 269 NOTE: By default, the IPv6 module determines the next-hop and 270 forwards the packet. However, optional parameters may ellicit 271 another behavior. For example, if a next-hop is provided as an 272 optional parameter, the IPv6 module forwards to that next-hop. 274 5.1. Computing Minimum CRH Length 276 The algorithm described in this section accepts the following CRH 277 fields as its input parameters: 279 o Routing Type (i.e., CRH-16 or CRH-32). 281 o Segments Left. 283 It yields L, the minimum CRH length. The minimum CRH length is 284 measured in 8-octet units, not including the first 8 octets. 286 288 switch(Routing Type) { 289 case CRH-16: 290 if (Segments Left <= 2) 291 return(0) 292 sidsBeyondFirstWord = Segments Left - 2; 293 sidPerWord = 4; 294 case CRH-32: 295 if (Segments Left <= 1) 296 return(0) 297 sidsBeyondFirstWord = Segments Left - 1; 298 sidsPerWord = 2; 299 case default: 300 return(0xFF); 301 } 303 words = sidsBeyondFirstWord div sidsPerWord; 304 if (sidsBeyondFirstWord mod sidsPerWord) 305 words++; 307 return(words) 309 311 6. Mutability 313 In the CRH, the Segments Left field is mutable. All remaining fields 314 are immutable. 316 7. Applications And SIDs 318 A CRH contains one or more SIDs. Each SID is processed by exactly 319 one node. 321 Therefore, a SID is not required to have domain-wide significance. 322 Applications can: 324 o Allocate SIDs so that they have domain-wide significance. 326 o Allocate SIDs so that they have node-local significance. 328 8. Management Considerations 330 PING and TRACEROUTE [RFC2151] both operate correctly in the presence 331 of the CRH. 333 9. Security Considerations 335 Networks that process the CRH MUST NOT accept packets containing the 336 CRH from untrusted sources. Their border routers SHOULD discard 337 packets that satisfy the following criteria: 339 o The packet contains a CRH 341 o The Segments Left field in the CRH has a value greater than 0 343 o The Destination Address field in the IPv6 header represents an 344 interface that resides inside of the network. 346 Many border routers cannot filter packets based upon the Segments 347 Left value. These border routers MAY discard packets that satisfy 348 the following criteria: 350 o The packet contains a CRH 352 o The Destination Address field in the IPv6 header represents an 353 interface that resides inside of the network. 355 10. Implementation and Deployment Status 357 Juniper Networks has produced experimental implementations of the CRH 358 on: 360 o A LINUX-based software platform 362 o The MX-series (ASIC-based) router 364 Liquid Telecom has deployed the CRH, on a limited basis, in their 365 network. Other experimental deployments are in progress. 367 11. IANA Considerations 369 SID values 0-15 are reserved for future use. They may be assigned by 370 IANA, based on IETF Consensus. IANA is requested to establish a 371 "Registry of CRH Reserved SIDs". Values 0-15 are reserved for future 372 use. 374 IANA is requested to make the following entries in the Internet 375 Protocol Version 6 (IPv6) Parameters "Routing Type" registry 376 [IANA-RH]: 378 Suggested 379 Value Description Reference 380 --------------------------------------------------------------------- 381 5 Compact Routing Header (16-bit) (CRH-16) This document 382 6 Compact Routing Header (32-bit) (CRH-32) This document 384 12. Acknowledgements 386 Thanks to Dr. Vanessa Ameen, Fernando Gont, Naveen Kottapalli, Joel 387 Halpern, Tony Li, Gerald Schmidt, Nancy Shaw, Ketan Talaulikar, and 388 Chandra Venkatraman for their contributions to this document. 390 13. Contributors 392 Daniam Henriques 394 Liquid Telecom 396 Johannesburg, South Africa 398 Email: daniam.henriques@liquidtelecom.com 400 Gang Chen 402 Baidu 404 No.10 Xibeiwang East Road Haidian District 406 Beijing 100193 P.R. China 408 Email: phdgang@gmail.com 410 Yifeng Zhou 412 ByteDance 414 Building 1, AVIC Plaza, 43 N 3rd Ring W Rd Haidian District 416 Beijing 100000 P.R. China 417 Email: yifeng.zhou@bytedance.com 419 Gyan Mishra 421 Verizon 423 Silver Spring, Maryland, USA 425 Email: hayabusagsm@gmail.com 427 14. References 429 14.1. Normative References 431 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 432 Requirement Levels", BCP 14, RFC 2119, 433 DOI 10.17487/RFC2119, March 1997, 434 . 436 [RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet 437 Control Message Protocol (ICMPv6) for the Internet 438 Protocol Version 6 (IPv6) Specification", STD 89, 439 RFC 4443, DOI 10.17487/RFC4443, March 2006, 440 . 442 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 443 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 444 May 2017, . 446 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 447 (IPv6) Specification", STD 86, RFC 8200, 448 DOI 10.17487/RFC8200, July 2017, 449 . 451 [RFC8201] McCann, J., Deering, S., Mogul, J., and R. Hinden, Ed., 452 "Path MTU Discovery for IP version 6", STD 87, RFC 8201, 453 DOI 10.17487/RFC8201, July 2017, 454 . 456 14.2. Informative References 458 [IANA-RH] IANA, "Routing Headers", 459 . 462 [ISO10589-Second-Edition] 463 International Organization for Standardization, 464 ""Intermediate system to Intermediate system intra-domain 465 routeing information exchange protocol for use in 466 conjunction with the protocol for providing the 467 connectionless-mode Network Service (ISO 8473)", ISO/IEC 468 10589:2002, Second Edition,", November 2001. 470 [RFC2151] Kessler, G. and S. Shepard, "A Primer On Internet and TCP/ 471 IP Tools and Utilities", FYI 30, RFC 2151, 472 DOI 10.17487/RFC2151, June 1997, 473 . 475 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 476 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 477 DOI 10.17487/RFC4271, January 2006, 478 . 480 [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF 481 for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, 482 . 484 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 485 Element (PCE) Communication Protocol (PCEP)", RFC 5440, 486 DOI 10.17487/RFC5440, March 2009, 487 . 489 [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., 490 and A. Bierman, Ed., "Network Configuration Protocol 491 (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011, 492 . 494 Appendix A. CRH Processing Examples 496 This appendix demonstrates CRH processing in the following scenarios: 498 o The SID list contains one entry for each segment in the path 499 (Appendix A.1). 501 o The SID list omits the first entry in the path (Appendix A.2). 503 ----------- ----------- ----------- 504 |Node: S | |Node: I1 | |Node: I2 | 505 |Loopback: |---------------|Loopback: |---------------|Loopback: | 506 |2001:db8::a| |2001:db8::1| |2001:db8::2| 507 ----------- ----------- ----------- 508 | | 509 | ----------- | 510 | |Node: D | | 511 ---------------------|Loopback: |--------------------- 512 |2001:db8::b| 513 ----------- 515 Figure 3: Reference Topology 517 Figure 3 provides a reference topology that is used in all examples. 519 +-----+--------------+-------------------+ 520 | SID | IPv6 Address | Forwarding Method | 521 +-----+--------------+-------------------+ 522 | 2 | 2001:db8::2 | Least-cost path | 523 | 11 | 2001:db8::b | Least-cost path | 524 +-----+--------------+-------------------+ 526 Table 1: Node SIDs 528 Table 1 describes two entries that appear in each node's CRH-FIB. 530 A.1. The SID List Contains One Entry For Each Segment In The Path 532 In this example, Node S sends a packet to Node D, via I2. In this 533 example, I2 appears in the CRH segment list. 535 +-------------------------------------+-------------------+ 536 | As the packet travels from S to I2: | | 537 +-------------------------------------+-------------------+ 538 | Source Address = 2001:db8::a | Segments Left = 1 | 539 | Destination Address = 2001:db8::2 | SID[0] = 11 | 540 | | SID[1] = 2 | 541 +-------------------------------------+-------------------+ 543 +-------------------------------------+-------------------+ 544 | As the packet travels from I2 to D: | | 545 +-------------------------------------+-------------------+ 546 | Source Address = 2001:db8::a | Segments Left = 0 | 547 | Destination Address = 2001:db8::b | SID[0] = 11 | 548 | | SID[1] = 2 | 549 +-------------------------------------+-------------------+ 551 A.2. The SID List Omits The First Entry In The Path 553 In this example, Node S sends a packet to Node D, via I2. In this 554 example, I2 does not appear in the CRH segment list. 556 +-------------------------------------+-------------------+ 557 | As the packet travels from S to I2: | | 558 +-------------------------------------+-------------------+ 559 | Source Address = 2001:db8::a | Segments Left = 1 | 560 | Destination Address = 2001:db8::2 | SID[0] = 11 | 561 +-------------------------------------+-------------------+ 563 +-------------------------------------+-------------------+ 564 | As the packet travels from I2 to D: | | 565 +-------------------------------------+-------------------+ 566 | Source Address = 2001:db8::a | Segments Left = 0 | 567 | Destination Address = 2001:db8::b | SID[0] = 11 | 568 +-------------------------------------+-------------------+ 570 Authors' Addresses 572 Ron Bonica 573 Juniper Networks 574 2251 Corporate Park Drive 575 Herndon, Virginia 20171 576 USA 578 Email: rbonica@juniper.net 580 Yuji Kamite 581 NTT Communications Corporation 582 3-4-1 Shibaura, Minato-ku 583 Tokyo 108-8118 584 Japan 586 Email: y.kamite@ntt.com 588 Tomonobu Niwa 589 KDDI 590 3-22-7, Yoyogi, Shibuya-ku 591 Tokyo 151-0053 592 Japan 594 Email: to-niwa@kddi.com 595 Andrew Alston 596 Liquid Telecom 597 Nairobi 598 Kenya 600 Email: Andrew.Alston@liquidtelecom.com 602 Luay Jalil 603 Verizon 604 Richardson, Texas 605 USA 607 Email: luay.jalil@one.verizon.com