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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 569 -- Looks like a reference, but probably isn't: '1' on line 544 Summary: 0 errors (**), 0 flaws (~~), 1 warning (==), 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: 18 November 2022 NTT Communications Corporation 6 A. Alston 7 D. Henriques 8 Liquid Telecom 9 L. Jalil 10 Verizon 11 17 May 2022 13 The IPv6 Compact Routing Header (CRH) 14 draft-bonica-6man-comp-rtg-hdr-28 16 Abstract 18 This document defines two new Routing header types. Collectively, 19 they are called the Compact Routing Headers (CRH). Individually, 20 they are called CRH-16 and CRH-32. 22 Status of This Memo 24 This Internet-Draft is submitted in full conformance with the 25 provisions of BCP 78 and BCP 79. 27 Internet-Drafts are working documents of the Internet Engineering 28 Task Force (IETF). Note that other groups may also distribute 29 working documents as Internet-Drafts. The list of current Internet- 30 Drafts is at https://datatracker.ietf.org/drafts/current/. 32 Internet-Drafts are draft documents valid for a maximum of six months 33 and may be updated, replaced, or obsoleted by other documents at any 34 time. It is inappropriate to use Internet-Drafts as reference 35 material or to cite them other than as "work in progress." 37 This Internet-Draft will expire on 18 November 2022. 39 Copyright Notice 41 Copyright (c) 2022 IETF Trust and the persons identified as the 42 document authors. All rights reserved. 44 This document is subject to BCP 78 and the IETF Trust's Legal 45 Provisions Relating to IETF Documents (https://trustee.ietf.org/ 46 license-info) in effect on the date of publication of this document. 47 Please review these documents carefully, as they describe your rights 48 and restrictions with respect to this document. Code Components 49 extracted from this document must include Revised BSD License text as 50 described in Section 4.e of the Trust Legal Provisions and are 51 provided without warranty as described in the Revised BSD License. 53 Table of Contents 55 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 56 2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3 57 3. The Compressed Routing Headers (CRH) . . . . . . . . . . . . 3 58 4. The CRH Forwarding Information Base (CRH-FIB) . . . . . . . . 4 59 5. Processing Rules . . . . . . . . . . . . . . . . . . . . . . 5 60 5.1. Computing Minimum CRH Length . . . . . . . . . . . . . . 6 61 6. Mutability . . . . . . . . . . . . . . . . . . . . . . . . . 7 62 7. Applications And SIDs . . . . . . . . . . . . . . . . . . . . 7 63 8. Management Considerations . . . . . . . . . . . . . . . . . . 7 64 9. Security Considerations . . . . . . . . . . . . . . . . . . . 8 65 10. Implementation and Deployment Status . . . . . . . . . . . . 8 66 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 67 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9 68 13. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 9 69 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 70 14.1. Normative References . . . . . . . . . . . . . . . . . . 9 71 14.2. Informative References . . . . . . . . . . . . . . . . . 10 72 Appendix A. CRH Processing Examples . . . . . . . . . . . . . . 11 73 A.1. The SID List Contains One Entry For Each Segment In The 74 Path . . . . . . . . . . . . . . . . . . . . . . . . . . 12 75 A.2. The SID List Omits The First Entry In The Path . . . . . 12 76 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13 78 1. Introduction 80 IPv6 [RFC8200] source nodes use Routing headers to specify the path 81 that a packet takes to its destination. The IETF has defined several 82 Routing header types [IANA-RH]. This document defines two new 83 Routing header types. Collectively, they are called the Compact 84 Routing Headers (CRH). Individually, they are called CRH-16 and CRH- 85 32. 87 The CRH allows IPv6 source nodes to specify the path that a packet 88 takes to its destination. The CRH: 90 * Can be encoded in relatively few bytes. 92 * Is designed to operate within a limited domain. (See Section 9). 94 The following are reasons for encoding the CRH in as few bytes as 95 possible: 97 * Many ASIC-based forwarders copy headers from buffer memory to on- 98 chip memory. As header sizes increase, so does the cost of this 99 copy. 101 * Because Path MTU Discovery (PMTUD) [RFC8201] is not entirely 102 reliable, many IPv6 hosts refrain from sending packets larger than 103 the IPv6 minimum link MTU (i.e., 1280 bytes). When packets are 104 small, the overhead imposed by large Routing Headers is excessive. 106 2. Requirements Language 108 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 109 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 110 "OPTIONAL" in this document are to be interpreted as described in BCP 111 14 [RFC2119] [RFC8174] when, and only when, they appear in all 112 capitals, as shown here. 114 3. The Compressed Routing Headers (CRH) 116 Both CRH versions (i.e., CRH-16 and CRH-32) contain the following 117 fields: 119 * Next Header - Defined in [RFC8200]. 121 * Hdr Ext Len - Defined in [RFC8200]. 123 * Routing Type - Defined in [RFC8200]. (CRH-16 value is 5. CRH-32 124 value is 6). 126 * Segments Left - Defined in [RFC8200]. 128 * Type-specific Data - Described in [RFC8200]. 130 In the CRH, the Type-specific data field contains a list of Segment 131 Identifiers (SIDs). Each SID represents both of the following: 133 * A segment of the path that the packet takes to its destination. 135 * An entry in the CRH Forwarding Information Base (CRH-FIB) 136 (Section 4). 138 SIDs are listed in reverse order. So, the first SID in the list 139 represents the final segment in the path. Because segments are 140 listed in reverse order, the Segments Left field can be used as an 141 index into the SID list. In this document, the "current SID" is the 142 SID list entry referenced by the Segments Left field. 144 The first segment in the path can be omitted from the list. See 145 Appendix A for examples. 147 In the CRH-16 (Figure 1), each SID is encoded in 16-bits. In the 148 CRH-32 (Figure 2), each SID is encoded in 32-bits. 150 In all cases, the CRH MUST end on a 64-bit boundary. So, the Type- 151 specific data field MUST be padded with zeros if the CRH would 152 otherwise not end on a 64-bit boundary. 154 0 1 2 3 155 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 1 156 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 157 | Next Header | Hdr Ext Len | Routing Type | Segments Left | 158 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 159 | SID[0] | SID[1] | 160 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-| 161 | ......... 162 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 164 Figure 1: CRH-16 166 0 1 2 3 167 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 1 168 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 169 | Next Header | Hdr Ext Len | Routing Type | Segments Left | 170 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 171 + SID[0] + 172 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 173 + SID[1] + 174 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 175 // // 176 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 177 + SID[n] + 178 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 180 Figure 2: CRH-32 182 4. The CRH Forwarding Information Base (CRH-FIB) 184 Each SID identifies a CRH-FIB entry. 186 Each CRH-FIB entry contains: 188 * An IPv6 address. 190 * A topological function. 192 * Arguments for the topological function. (Optional). 194 The first ten bits of the IPv6 address MUST NOT be fe00. That prefix 195 is reserved for link-local [RFC6890] addresses. 197 The topological function specifies how the processing node forwards 198 the packet to the next segment endpoint. The following are examples: 200 * Forward the packet through the least-cost path to the next segment 201 endpoint. 203 * Forward the packet through a specified interface. 205 * Encapsulate the packet in another IPv6 header of any type (e.g., 206 MPLS, IPv6) and forward either through the least cost path or a 207 specified interface. 209 Some topological functions require parameters. For example, a 210 topological function might require a parameter that identifies the 211 interface through which the packet should be forwarded. 213 The CRH-FIB can be populated: 215 * By an operator, using a Command Line Interface (CLI). 217 * By a controller, using the Path Computation Element (PCE) 218 Communication Protocol (PCEP) [RFC5440] or the Network 219 Configuration Protocol (NETCONF) [RFC6241]. 221 * By a distributed routing protocol [ISO10589-Second-Edition], 222 [RFC5340], [RFC4271]. 224 5. Processing Rules 226 The following rules describe CRH processing: 228 * If Segments Left equals 0, skip over the CRH and process the next 229 header in the packet. 231 * If Hdr Ext Len indicates that the CRH is larger than the 232 implementation can process, discard the packet and send an ICMPv6 233 [RFC4443] Parameter Problem, Code 0, message to the Source 234 Address, pointing to the Hdr Ext Len field. 236 * Compute L, the minimum CRH length ( Section 5.1). 238 * If L is greater than Hdr Ext Len, discard the packet and send an 239 ICMPv6 Parameter Problem, Code 0, message to the Source Address, 240 pointing to the Segments Left field. 242 * Decrement Segments Left. 244 * Search for the current SID in the CRH-FIB. In this document, the 245 "current SID" is the SID list entry referenced by the Segments 246 Left field. 248 * If the search does not return a CRH-FIB entry, discard the packet 249 and send an ICMPv6 Parameter Problem, Code 0, message to the 250 Source Address, pointing to the current SID. 252 * If Segments Left is greater than 0 and the CRH-FIB entry contains 253 a multicast address, discard the packet and send an ICMPv6 254 Parameter Problem, Code 0, message to the Source Address, pointing 255 to the current SID. 257 * Copy the IPv6 address from the CRH-FIB entry to the Destination 258 Address field in the IPv6 header. 260 * Decrement the IPv6 Hop Limit. 262 * Submit the packet, its topological function and its parameters to 263 the IPv6 module. See NOTE. 265 NOTE: By default, the IPv6 module determines the next-hop and 266 forwards the packet. However, the topological function may elicit 267 another behavior. For example, the IPv6 module may forward the 268 packet through a specified interface. 270 5.1. Computing Minimum CRH Length 272 The algorithm described in this section accepts the following CRH 273 fields as its input parameters: 275 * Routing Type (i.e., CRH-16 or CRH-32). 277 * Segments Left. 279 It yields L, the minimum CRH length. The minimum CRH length is 280 measured in 8-octet units, not including the first 8 octets. 282 283 switch(Routing Type) { 284 case CRH-16: 285 if (Segments Left <= 2) 286 return(0) 287 sidsBeyondFirstWord = Segments Left - 2; 288 sidPerWord = 4; 289 case CRH-32: 290 if (Segments Left <= 1) 291 return(0) 292 sidsBeyondFirstWord = Segments Left - 1; 293 sidsPerWord = 2; 294 case default: 295 return(0xFF); 296 } 298 words = sidsBeyondFirstWord div sidsPerWord; 299 if (sidsBeyondFirstWord mod sidsPerWord) 300 words++; 302 return(words) 303 305 6. Mutability 307 In the CRH, the Segments Left field is mutable. All remaining fields 308 are immutable. 310 7. Applications And SIDs 312 A CRH contains one or more SIDs. Each SID is processed by exactly 313 one node. 315 Therefore, a SID is not required to have domain-wide significance. 316 Applications can: 318 * Allocate SIDs so that they have domain-wide significance. 320 * Allocate SIDs so that they have node-local significance. 322 8. Management Considerations 324 PING and TRACEROUTE [RFC2151] both operate correctly in the presence 325 of the CRH. 327 9. Security Considerations 329 Networks that process the CRH MUST NOT accept packets containing the 330 CRH from outside of there limited domain.. Their border routers 331 SHOULD discard packets that satisfy the following criteria: 333 * The packet contains a CRH 335 * The Segments Left field in the CRH has a value greater than 0 337 * The Destination Address field in the IPv6 header represents an 338 interface that resides inside of the network. 340 Many border routers cannot filter packets based upon the Segments 341 Left value. These border routers MAY discard packets that satisfy 342 the following criteria: 344 * The packet contains a CRH 346 * The Destination Address field in the IPv6 header represents an 347 interface that resides inside of the network. 349 10. Implementation and Deployment Status 351 Juniper Networks has produced experimental implementations of the CRH 352 on: 354 * A LINUX-based software platform 356 * The MX-series (ASIC-based) router 358 Liquid Telecom has deployed the CRH, on a limited basis, in their 359 network. Other experimental deployments are in progress. 361 11. IANA Considerations 363 This document makes the following registrations in the "Internet 364 Protocol Version 6 (IPv6) Parameters" "Routing Types" subregistry 365 maintained by IANA: 367 +-------+------------------------------+---------------+ 368 | Value | Description | Reference | 369 +=======+==============================+===============+ 370 | 5 | CRH-16 | This document | 371 +-------+------------------------------+---------------+ 372 | 6 | CRH-32 | This document | 373 +-------+------------------------------+---------------+ 375 12. Acknowledgements 377 Thanks to Dr. Vanessa Ameen, Fernando Gont, Naveen Kottapalli, Joel 378 Halpern, Tony Li, Gerald Schmidt, Nancy Shaw, Ketan Talaulikar, and 379 Chandra Venkatraman for their contributions to this document. 381 13. Contributors 383 Gang Chen 385 Baidu 387 No.10 Xibeiwang East Road Haidian District 389 Beijing 100193 P.R. China 391 Email: phdgang@gmail.com 393 Yifeng Zhou 395 ByteDance 397 Building 1, AVIC Plaza, 43 N 3rd Ring W Rd Haidian District 399 Beijing 100000 P.R. China 401 Email: yifeng.zhou@bytedance.com 403 Gyan Mishra 405 Verizon 407 Silver Spring, Maryland, USA 409 Email: hayabusagsm@gmail.com 411 14. References 413 14.1. Normative References 415 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 416 Requirement Levels", BCP 14, RFC 2119, 417 DOI 10.17487/RFC2119, March 1997, 418 . 420 [RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet 421 Control Message Protocol (ICMPv6) for the Internet 422 Protocol Version 6 (IPv6) Specification", STD 89, 423 RFC 4443, DOI 10.17487/RFC4443, March 2006, 424 . 426 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 427 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 428 May 2017, . 430 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 431 (IPv6) Specification", STD 86, RFC 8200, 432 DOI 10.17487/RFC8200, July 2017, 433 . 435 [RFC8201] McCann, J., Deering, S., Mogul, J., and R. Hinden, Ed., 436 "Path MTU Discovery for IP version 6", STD 87, RFC 8201, 437 DOI 10.17487/RFC8201, July 2017, 438 . 440 14.2. Informative References 442 [IANA-RH] IANA, "Routing Headers", 443 . 446 [ISO10589-Second-Edition] 447 International Organization for Standardization, 448 ""Intermediate system to Intermediate system intra-domain 449 routeing information exchange protocol for use in 450 conjunction with the protocol for providing the 451 connectionless-mode Network Service (ISO 8473)", ISO/IEC 452 10589:2002, Second Edition,", November 2001. 454 [RFC2151] Kessler, G. and S. Shepard, "A Primer On Internet and TCP/ 455 IP Tools and Utilities", FYI 30, RFC 2151, 456 DOI 10.17487/RFC2151, June 1997, 457 . 459 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 460 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 461 DOI 10.17487/RFC4271, January 2006, 462 . 464 [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF 465 for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, 466 . 468 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 469 Element (PCE) Communication Protocol (PCEP)", RFC 5440, 470 DOI 10.17487/RFC5440, March 2009, 471 . 473 [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., 474 and A. Bierman, Ed., "Network Configuration Protocol 475 (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011, 476 . 478 [RFC6890] Cotton, M., Vegoda, L., Bonica, R., Ed., and B. Haberman, 479 "Special-Purpose IP Address Registries", BCP 153, 480 RFC 6890, DOI 10.17487/RFC6890, April 2013, 481 . 483 Appendix A. CRH Processing Examples 485 This appendix demonstrates CRH processing in the following scenarios: 487 * The SID list contains one entry for each segment in the path 488 (Appendix A.1). 490 * The SID list omits the first entry in the path (Appendix A.2). 492 ----------- ----------- ----------- 493 |Node: S | |Node: I1 | |Node: I2 | 494 |Loopback: |---------------|Loopback: |---------------|Loopback: | 495 |2001:db8::a| |2001:db8::1| |2001:db8::2| 496 ----------- ----------- ----------- 497 | | 498 | ----------- | 499 | |Node: D | | 500 ---------------------|Loopback: |--------------------- 501 |2001:db8::b| 502 ----------- 504 Figure 3: Reference Topology 506 Figure 3 provides a reference topology that is used in all examples. 508 +=====+==============+===================+ 509 | SID | IPv6 Address | Forwarding Method | 510 +=====+==============+===================+ 511 | 2 | 2001:db8::2 | Least-cost path | 512 +-----+--------------+-------------------+ 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 +-------------------------------------+-------------------+ 530 | Destination Address = 2001:db8::2 | SID[0] = 11 | 531 +-------------------------------------+-------------------+ 532 | | SID[1] = 2 | 533 +-------------------------------------+-------------------+ 535 Table 2 537 +=====================================+===================+ 538 | As the packet travels from I2 to D: | | 539 +=====================================+===================+ 540 | Source Address = 2001:db8::a | Segments Left = 0 | 541 +-------------------------------------+-------------------+ 542 | Destination Address = 2001:db8::b | SID[0] = 11 | 543 +-------------------------------------+-------------------+ 544 | | SID[1] = 2 | 545 +-------------------------------------+-------------------+ 547 Table 3 549 A.2. The SID List Omits The First Entry In The Path 551 In this example, Node S sends a packet to Node D, via I2. In this 552 example, I2 does not appear in the CRH segment list. 554 +=====================================+===================+ 555 | As the packet travels from S to I2: | | 556 +=====================================+===================+ 557 | Source Address = 2001:db8::a | Segments Left = 1 | 558 +-------------------------------------+-------------------+ 559 | Destination Address = 2001:db8::2 | SID[0] = 11 | 560 +-------------------------------------+-------------------+ 562 Table 4 564 +=====================================+===================+ 565 | As the packet travels from I2 to D: | | 566 +=====================================+===================+ 567 | Source Address = 2001:db8::a | Segments Left = 0 | 568 +-------------------------------------+-------------------+ 569 | Destination Address = 2001:db8::b | SID[0] = 11 | 570 +-------------------------------------+-------------------+ 572 Table 5 574 Authors' Addresses 576 Ron Bonica 577 Juniper Networks 578 2251 Corporate Park Drive 579 Herndon, Virginia 20171 580 United States of America 581 Email: rbonica@juniper.net 583 Yuji Kamite 584 NTT Communications Corporation 585 3-4-1 Shibaura, Minato-ku, 586 108-8118 587 Japan 588 Email: y.kamite@ntt.com 590 Andrew Alston 591 Liquid Telecom 592 Nairobi 593 Kenya 594 Email: Andrew.Alston@liquidtelecom.com 595 Daniam Henriques 596 Liquid Telecom 597 Johannesburg 598 South Africa 599 Email: daniam.henriques@liquidtelecom.com 601 Luay Jalil 602 Verizon 603 Richardson, Texas 604 United States of America 605 Email: luay.jalil@one.verizon.com