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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 574 -- Looks like a reference, but probably isn't: '1' on line 555 == Unused Reference: 'RFC4443' is defined on line 443, 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: April 9, 2021 NTT Communications Corporation 6 A. Alston 7 D. Henriques 8 Liquid Telecom 9 L. Jalil 10 Verizon 11 October 6, 2020 13 The IPv6 Compact Routing Header (CRH) 14 draft-bonica-6man-comp-rtg-hdr-23 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 April 9, 2021. 39 Copyright Notice 41 Copyright (c) 2020 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 46 (https://trustee.ietf.org/license-info) in effect on the date of 47 publication of this document. Please review these documents 48 carefully, as they describe your rights and restrictions with respect 49 to this document. Code Components extracted from this document must 50 include Simplified BSD License text as described in Section 4.e of 51 the Trust Legal Provisions and are provided without warranty as 52 described in the Simplified BSD License. 54 Table of Contents 56 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 57 2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3 58 3. The Compressed Routing Headers (CRH) . . . . . . . . . . . . 3 59 4. The CRH Forwarding Information Base (CRH-FIB) . . . . . . . 4 60 5. Processing Rules . . . . . . . . . . . . . . . . . . . . . . 6 61 5.1. Computing Minimum CRH Length . . . . . . . . . . . . . . 7 62 6. Mutability . . . . . . . . . . . . . . . . . . . . . . . . . 8 63 7. Applications And SIDs . . . . . . . . . . . . . . . . . . . . 8 64 8. Management Considerations . . . . . . . . . . . . . . . . . . 8 65 9. Security Considerations . . . . . . . . . . . . . . . . . . . 8 66 10. Implementation and Deployment Status . . . . . . . . . . . . 9 67 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 68 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9 69 13. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 9 70 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 71 14.1. Normative References . . . . . . . . . . . . . . . . . . 10 72 14.2. Informative References . . . . . . . . . . . . . . . . . 11 73 Appendix A. CRH Processing Examples . . . . . . . . . . . . . . 11 74 A.1. The SID List Contains One Entry For Each Segment In The 75 Path . . . . . . . . . . . . . . . . . . . . . . . . . . 12 76 A.2. The SID List Omits The First Entry In The Path . . . . . 13 77 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13 79 1. Introduction 81 IPv6 [RFC8200] source nodes use Routing headers to specify the path 82 that a packet takes to its destination. The IETF has defined several 83 Routing header types [IANA-RH]. This document defines two new 84 Routing header types. Collectively, they are called the Compact 85 Routing Headers (CRH). Individually, they are called CRH-16 and CRH- 86 32. 88 The CRH allows IPv6 source nodes to specify the path that a packet 89 takes to its destination. The CRH: 91 o Can be encoded in relatively few bytes. 93 o Is designed to operate within a network domain. (See Section 9). 95 The following are reasons for encoding the CRH in as few bytes as 96 possible: 98 o Many ASIC-based forwarders copy all headers from buffer memory to 99 on-chip memory. As header sizes increase, so does the cost of 100 this copy. 102 o Because Path MTU Discovery (PMTUD) [RFC8201] is not entirely 103 reliable, many IPv6 hosts refrain from sending packets larger than 104 the IPv6 minimum link MTU (i.e., 1280 bytes). When packets are 105 small, the overhead imposed by large Routing Headers is excessive. 107 2. Requirements Language 109 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 110 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 111 "OPTIONAL" in this document are to be interpreted as described in BCP 112 14 [RFC2119] [RFC8174] when, and only when, they appear in all 113 capitals, as shown here. 115 3. The Compressed Routing Headers (CRH) 117 Both CRH versions (i.e., CRH-16 and CRH-32) contain the following 118 fields: 120 o Next Header - Defined in [RFC8200]. 122 o Hdr Ext Len - Defined in [RFC8200]. 124 o Routing Type - Defined in [RFC8200]. Value TBD by IANA. (For 125 CRH-16, the suggested value is 5. For CRH-32, the suggested value 126 is 6.) 128 o Segments Left - Defined in [RFC8200]. 130 o Type-specific Data - Described in [RFC8200]. 132 In the CRH, the Type-specific data field contains a list of Segment 133 Identifiers (SIDs). Each SID represents both of the following: 135 o A segment of the path that the packet takes to its destination. 137 o An entry in the CRH Forwarding Information Base (CRH-FIB) 138 (Section 4). 140 SIDs are listed in reverse order. So, the first SID in the list 141 represents the final segment in the path. Because segments are 142 listed in reverse order, the Segments Left field can be used as an 143 index into the SID list. In this document, the "current SID" is the 144 SID list entry referenced by the Segments Left field. 146 The first segment in the path can be omitted from the list. See 147 (Appendix A) for examples. 149 In the CRH-16 (Figure 1), each SID is encoded in 16-bits. In the 150 CRH-32 (Figure 2), each SID is encoded in 32-bits. 152 In all cases, the CRH MUST end on a 64-bit boundary. So, the Type- 153 specific data field MUST be padded with zeros if the CRH would 154 otherwise not end on a 64-bit boundary. 156 0 1 2 3 157 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 1 158 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 159 | Next Header | Hdr Ext Len | Routing Type | Segments Left | 160 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 161 | SID[0] | SID[1] | 162 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-| 163 | ......... 164 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 166 Figure 1: CRH-16 168 0 1 2 3 169 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 1 170 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 171 | Next Header | Hdr Ext Len | Routing Type | Segments Left | 172 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 173 + SID[0] + 174 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 175 + SID[1] + 176 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 177 // // 178 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 179 + SID[n] + 180 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 182 Figure 2: CRH-32 184 4. The CRH Forwarding Information Base (CRH-FIB) 186 Each SID identifies a CRH-FIB entry. 188 Each CRH-FIB entry contains: 190 o A IPv6 address. 192 o An optional, node specific instruction. 194 o A forwarding method. 196 o Method-specific parameters (optional). 198 The IPv6 address represents an interface on the next segment 199 endpoint. It MUST NOT be a link-local address. While the IPv6 200 address represents an interface on the next segment endpoint, it does 201 not necessarily represent the interface through which the packet will 202 arrive at the next segment endpoint. 204 The node specific instruction is optional. If present, it invokes a 205 node specific procedure. Node specific procedures are not subject to 206 standardization. A node can support any number of node specific 207 procedures and associate them with any identifiers. The identifiers 208 have node local significance. The following are examples of node 209 specific procedures: 211 o Emit telemetry. 213 o Subject the packet's payload to a firewall rule. 215 o Replicate the packet, forwarding one copy and retaining the other 216 for sampling, analysis or other purposes. 218 The forwarding method specifies how the processing node will forward 219 the packet to the next segment endpoint. The following are examples: 221 o Forward the packet to the next-hop along the least-cost path to 222 the next segment endpoint. 224 o Forward the packet through a specified interface to the next 225 segment endpoint. 227 Some forwarding methods require method-specific parameters. For 228 example, a forwarding method might require a parameter that 229 identifies the interface through which the packet should be 230 forwarded. 232 The CRH-FIB can be populated: 234 o By an operator, using a Command Line Interface (CLI). 236 o By a controller, using the Path Computation Element (PCE) 237 Communication Protocol (PCEP) [RFC5440] or the Network 238 Configuration Protocol (NETCONF) [RFC6241]. 240 o By a distributed routing protocol [ISO10589-Second-Edition], 241 [RFC5340], [RFC4271]. 243 5. Processing Rules 245 The following rules describe CRH processing: 247 o If Segments Left equals 0, skip over the CRH and process the next 248 header in the packet. 250 o If Hdr Ext Len indicates that the CRH is larger than the 251 implementation can process, discard the packet and send an ICMPv6 252 Parameter Problem, Code 0, message to the Source Address, pointing 253 to the Hdr Ext Len field. 255 o Compute L, the minimum CRH length (See (Section 5.1)). 257 o If L is greater than Hdr Ext Len, discard the packet and send an 258 ICMPv6 Parameter Problem, Code 0, message to the Source Address, 259 pointing to the Segments Left field. 261 o Decrement Segments Left. 263 o Search for the current SID in the CRH-FIB. In this document, the 264 "current SID" is the SID list entry referenced by the Segments 265 Left field. 267 o If the search does not return a CRH-FIB entry, discard the packet 268 and send an ICMPv6 Parameter Problem, Code 0, message to the 269 Source Address, pointing to the current SID. 271 o If Segments Left is greater than 0 and the CRH-FIB entry contains 272 a multicast address, discard the packet and send an ICMPv6 273 Parameter Problem, Code 0, message to the Source Address, pointing 274 to the current SID. 276 o Copy the IPv6 address from the CRH-FIB entry to the Destination 277 Address field in the IPv6 header. 279 o Decrement the IPv6 Hop Limit. 281 o If the CRH-FIB entry contains a node specific instruction, execute 282 it. 284 o Submit the packet and optional parameters to the IPv6 module. 285 Optional parameters are derived from the CRH-SID. See NOTE. 287 NOTE: By default, the IPv6 module determines the next-hop and 288 forwards the packet. However, optional parameters may ellicit 289 another behavior. For example, if a next-hop is provided as an 290 optional parameter, the IPv6 module forwards to that next-hop. 292 5.1. Computing Minimum CRH Length 294 The algorithm described in this section accepts the following CRH 295 fields as its input parameters: 297 o Routing Type (i.e., CRH-16 or CRH-32). 299 o Segments Left. 301 It yields L, the minimum CRH length. The minimum CRH length is 302 measured in 8-octet units, not including the first 8 octets. 304 306 switch(Routing Type) { 307 case CRH-16: 308 if (Segments Left <= 2) 309 return(0) 310 sidsBeyondFirstWord = Segments Left - 2; 311 sidPerWord = 4; 312 case CRH-32: 313 if (Segments Left <= 1) 314 return(0) 315 sidsBeyondFirstWord = Segments Left - 1; 316 sidsPerWord = 2; 317 case default: 318 return(0xFF); 319 } 321 words = sidsBeyondFirstWord div sidsPerWord; 322 if (sidsBeyondFirstWord mod sidsPerWord) 323 words++; 325 return(words) 327 329 6. Mutability 331 In the CRH, the Segments Left field is mutable. All remaining fields 332 are immutable. 334 7. Applications And SIDs 336 A CRH contains one or more SIDs. Each SID is processed by exactly 337 one node. 339 Therefore, a SID is not required to have domain-wide significance. 340 Applications can: 342 o Allocate SIDs so that they have domain-wide significance. 344 o Allocate SIDs so that they have node-local significance. 346 8. Management Considerations 348 PING and TRACEROUTE [RFC2151] both operate correctly in the presence 349 of the CRH. 351 9. Security Considerations 353 Networks that process the CRH MUST NOT accept packets containing the 354 CRH from untrusted sources. Their border routers SHOULD discard 355 packets that satisfy the following criteria: 357 o The packet contains a CRH 359 o The Segments Left field in the CRH has a value greater than 0 361 o The Destination Address field in the IPv6 header represents an 362 interface that resides inside of the network. 364 Many border routers cannot filter packets based upon the Segments 365 Left value. These border routers MAY discard packets that satisfy 366 the following criteria: 368 o The packet contains a CRH 370 o The Destination Address field in the IPv6 header represents an 371 interface that resides inside of the network. 373 10. Implementation and Deployment Status 375 Juniper Networks has produced experimental implementations of the CRH 376 on: 378 o A LINUX-based software platform 380 o The MX-series (ASIC-based) router 382 Liquid Telecom has deployed the CRH, on a limited basis, in their 383 network. Other experimental deployments are in progress. 385 11. IANA Considerations 387 This document makes the following registrations in the "Internet 388 Protocol Version 6 (IPv6) Parameters" "Routing Types" subregistry 389 maintained by IANA: 391 +-------+------------------------------+---------------+ 392 | Value | Description | Reference | 393 +=======+==============================+===============+ 394 | 5 | CRH-16 | This document | 395 +-------+------------------------------+---------------+ 396 | 6 | CRH-32 | This document | 397 +-------+------------------------------+---------------+ 399 12. Acknowledgements 401 Thanks to Dr. Vanessa Ameen, Fernando Gont, Naveen Kottapalli, Joel 402 Halpern, Tony Li, Gerald Schmidt, Nancy Shaw, Ketan Talaulikar, and 403 Chandra Venkatraman for their contributions to this document. 405 13. Contributors 407 Gang Chen 409 Baidu 411 No.10 Xibeiwang East Road Haidian District 413 Beijing 100193 P.R. China 415 Email: phdgang@gmail.com 417 Yifeng Zhou 418 ByteDance 420 Building 1, AVIC Plaza, 43 N 3rd Ring W Rd Haidian District 422 Beijing 100000 P.R. China 424 Email: yifeng.zhou@bytedance.com 426 Gyan Mishra 428 Verizon 430 Silver Spring, Maryland, USA 432 Email: hayabusagsm@gmail.com 434 14. References 436 14.1. Normative References 438 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 439 Requirement Levels", BCP 14, RFC 2119, 440 DOI 10.17487/RFC2119, March 1997, 441 . 443 [RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet 444 Control Message Protocol (ICMPv6) for the Internet 445 Protocol Version 6 (IPv6) Specification", STD 89, 446 RFC 4443, DOI 10.17487/RFC4443, March 2006, 447 . 449 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 450 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 451 May 2017, . 453 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 454 (IPv6) Specification", STD 86, RFC 8200, 455 DOI 10.17487/RFC8200, July 2017, 456 . 458 [RFC8201] McCann, J., Deering, S., Mogul, J., and R. Hinden, Ed., 459 "Path MTU Discovery for IP version 6", STD 87, RFC 8201, 460 DOI 10.17487/RFC8201, July 2017, 461 . 463 14.2. Informative References 465 [IANA-RH] IANA, "Routing Headers", 466 . 469 [ISO10589-Second-Edition] 470 International Organization for Standardization, 471 ""Intermediate system to Intermediate system intra-domain 472 routeing information exchange protocol for use in 473 conjunction with the protocol for providing the 474 connectionless-mode Network Service (ISO 8473)", ISO/IEC 475 10589:2002, Second Edition,", November 2001. 477 [RFC2151] Kessler, G. and S. Shepard, "A Primer On Internet and TCP/ 478 IP Tools and Utilities", FYI 30, RFC 2151, 479 DOI 10.17487/RFC2151, June 1997, 480 . 482 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 483 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 484 DOI 10.17487/RFC4271, January 2006, 485 . 487 [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF 488 for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, 489 . 491 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 492 Element (PCE) Communication Protocol (PCEP)", RFC 5440, 493 DOI 10.17487/RFC5440, March 2009, 494 . 496 [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., 497 and A. Bierman, Ed., "Network Configuration Protocol 498 (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011, 499 . 501 Appendix A. CRH Processing Examples 503 This appendix demonstrates CRH processing in the following scenarios: 505 o The SID list contains one entry for each segment in the path 506 (Appendix A.1). 508 o The SID list omits the first entry in the path (Appendix A.2). 510 ----------- ----------- ----------- 511 |Node: S | |Node: I1 | |Node: I2 | 512 |Loopback: |---------------|Loopback: |---------------|Loopback: | 513 |2001:db8::a| |2001:db8::1| |2001:db8::2| 514 ----------- ----------- ----------- 515 | | 516 | ----------- | 517 | |Node: D | | 518 ---------------------|Loopback: |--------------------- 519 |2001:db8::b| 520 ----------- 522 Figure 3: Reference Topology 524 Figure 3 provides a reference topology that is used in all examples. 526 +-----+--------------+-------------------+ 527 | SID | IPv6 Address | Forwarding Method | 528 +-----+--------------+-------------------+ 529 | 2 | 2001:db8::2 | Least-cost path | 530 | 11 | 2001:db8::b | Least-cost path | 531 +-----+--------------+-------------------+ 533 Table 1: Node SIDs 535 Table 1 describes two entries that appear in each node's CRH-FIB. 537 A.1. The SID List Contains One Entry For Each Segment In The Path 539 In this example, Node S sends a packet to Node D, via I2. In this 540 example, I2 appears in the CRH segment list. 542 +-------------------------------------+-------------------+ 543 | As the packet travels from S to I2: | | 544 +-------------------------------------+-------------------+ 545 | Source Address = 2001:db8::a | Segments Left = 1 | 546 | Destination Address = 2001:db8::2 | SID[0] = 11 | 547 | | SID[1] = 2 | 548 +-------------------------------------+-------------------+ 550 +-------------------------------------+-------------------+ 551 | As the packet travels from I2 to D: | | 552 +-------------------------------------+-------------------+ 553 | Source Address = 2001:db8::a | Segments Left = 0 | 554 | Destination Address = 2001:db8::b | SID[0] = 11 | 555 | | SID[1] = 2 | 556 +-------------------------------------+-------------------+ 558 A.2. The SID List Omits The First Entry In The Path 560 In this example, Node S sends a packet to Node D, via I2. In this 561 example, I2 does not appear in the CRH segment list. 563 +-------------------------------------+-------------------+ 564 | As the packet travels from S to I2: | | 565 +-------------------------------------+-------------------+ 566 | Source Address = 2001:db8::a | Segments Left = 1 | 567 | Destination Address = 2001:db8::2 | SID[0] = 11 | 568 +-------------------------------------+-------------------+ 570 +-------------------------------------+-------------------+ 571 | As the packet travels from I2 to D: | | 572 +-------------------------------------+-------------------+ 573 | Source Address = 2001:db8::a | Segments Left = 0 | 574 | Destination Address = 2001:db8::b | SID[0] = 11 | 575 +-------------------------------------+-------------------+ 577 Authors' Addresses 579 Ron Bonica 580 Juniper Networks 581 2251 Corporate Park Drive 582 Herndon, Virginia 20171 583 USA 585 Email: rbonica@juniper.net 587 Yuji Kamite 588 NTT Communications Corporation 589 3-4-1 Shibaura, Minato-ku 590 Tokyo 108-8118 591 Japan 593 Email: y.kamite@ntt.com 595 Andrew Alston 596 Liquid Telecom 597 Nairobi 598 Kenya 600 Email: Andrew.Alston@liquidtelecom.com 601 Daniam Henriques 602 Liquid Telecom 603 Johannesburg 604 South Africa 606 Email: daniam.henriques@liquidtelecom.com 608 Luay Jalil 609 Verizon 610 Richardson, Texas 611 USA 613 Email: luay.jalil@one.verizon.com