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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 SPRING Working Group W. Cheng 3 Internet-Draft China Mobile 4 Intended status: Standards Track Z. Li 5 Expires: April 28, 2022 C. Li 6 Huawei Technologies 7 F. Clad 8 Cisco Systems, Inc 9 A. Liu 10 ZTE Corporation 11 C. Xie 12 China Telecom 13 Y. Liu 14 China Mobile 15 S. Zadok 16 Broadcom 17 October 25, 2021 19 Generalized SRv6 Network Programming for SRv6 Compression 20 draft-cl-spring-generalized-srv6-for-cmpr-04 22 Abstract 24 This document proposes Generalized Segment Routing over IPv6 (G-SRv6) 25 Networking Programming for SRv6 compression. 27 G-SRv6 can reduce the overhead of SRv6 by encoding the Generalized 28 SIDs(G-SID) in SID list, and it also supports to program SRv6 SIDs 29 and G-SIDs in a single SRH to support incremental deployment and 30 smooth upgrade. 32 G-SRv6 is fully compatible with SRv6 with no modification of SRH, no 33 new address consumption, no new route creation, and even no 34 modification of control plane. 36 G-SRv6 for Compression is designed based on the Compressed SRv6 37 Segment List Encoding in SRH 38 [I-D.filsfilscheng-spring-srv6-srh-compression] framework. 40 Status of This Memo 42 This Internet-Draft is submitted in full conformance with the 43 provisions of BCP 78 and BCP 79. 45 Internet-Drafts are working documents of the Internet Engineering 46 Task Force (IETF). Note that other groups may also distribute 47 working documents as Internet-Drafts. The list of current Internet- 48 Drafts is at https://datatracker.ietf.org/drafts/current/. 50 Internet-Drafts are draft documents valid for a maximum of six months 51 and may be updated, replaced, or obsoleted by other documents at any 52 time. It is inappropriate to use Internet-Drafts as reference 53 material or to cite them other than as "work in progress." 55 This Internet-Draft will expire on April 28, 2022. 57 Copyright Notice 59 Copyright (c) 2021 IETF Trust and the persons identified as the 60 document authors. All rights reserved. 62 This document is subject to BCP 78 and the IETF Trust's Legal 63 Provisions Relating to IETF Documents 64 (https://trustee.ietf.org/license-info) in effect on the date of 65 publication of this document. Please review these documents 66 carefully, as they describe your rights and restrictions with respect 67 to this document. Code Components extracted from this document must 68 include Simplified BSD License text as described in Section 4.e of 69 the Trust Legal Provisions and are provided without warranty as 70 described in the Simplified BSD License. 72 Table of Contents 74 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 75 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 76 2.1. Requirements Language . . . . . . . . . . . . . . . . . . 4 77 3. Concepts of G-SRv6 . . . . . . . . . . . . . . . . . . . . . 4 78 3.1. G-SID . . . . . . . . . . . . . . . . . . . . . . . . . . 4 79 3.2. G-SID Container . . . . . . . . . . . . . . . . . . . . . 5 80 3.3. G-SID Index . . . . . . . . . . . . . . . . . . . . . . . 6 81 3.4. COC Flavor . . . . . . . . . . . . . . . . . . . . . . . 6 82 4. G-SRH . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 83 5. Packet Processing . . . . . . . . . . . . . . . . . . . . . . 9 84 6. Illustration . . . . . . . . . . . . . . . . . . . . . . . . 10 85 7. Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . 12 86 8. Running Code . . . . . . . . . . . . . . . . . . . . . . . . 13 87 8.1. Interop-test Status . . . . . . . . . . . . . . . . . . . 13 88 8.2. Deployment Status . . . . . . . . . . . . . . . . . . . . 15 89 9. Protocol Extensions Requirements . . . . . . . . . . . . . . 15 90 9.1. Data Plane . . . . . . . . . . . . . . . . . . . . . . . 15 91 9.2. Control Plane . . . . . . . . . . . . . . . . . . . . . . 16 92 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 93 11. Security Considerations . . . . . . . . . . . . . . . . . . . 17 94 12. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 17 95 13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 17 96 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 17 97 14.1. Normative References . . . . . . . . . . . . . . . . . . 17 98 14.2. Informative References . . . . . . . . . . . . . . . . . 18 99 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18 101 1. Introduction 103 Segment routing (SR) [RFC8402] is a source routing paradigm that 104 explicitly indicates the forwarding path for packets at the ingress 105 node by inserting an ordered list of instructions, called segments. 107 When segment routing is deployed on the IPv6 data plane, it is called 108 SRv6 [RFC8754]. For support of SR, a new routing header called 109 Segment Routing Header (SRH), which contains a list of SIDs and other 110 information, has been defined in [RFC8754]. In use cases like 111 Traffic Engineering, an ordered SID List with multiple SIDs is 112 inserted into the SRH to steer packets along an explicit path. 114 However, the size of SIDs (16 bytes per SID) in SRH proposes 115 challenges for packet processing and payload efficiency 116 [I-D.ietf-spring-compression-requirement]. In order to solve this 117 problem, this document proposes Generalized Segment Routing over IPv6 118 (G-SRv6) Networking Programming for SRv6 compression. 120 G-SRv6 supports to encode multiple types of Segments in an SRH, 121 called Generalized SRH (G-SRH). In SRv6 Compression, the G-SRH can 122 carry multiple SRv6 SID and G-SID(Generalized Segment Identifier) 123 containers in the SID list. A G-SID container may include an SRv6 124 SID or multiple G-SIDs and optional padding. A G-SID can be a 125 32-bits value of the original SRv6 SID, which contains the node ID 126 and function ID. By carrying G-SIDs instead of 128 bits SRv6 SID, 127 the problem of SRv6 header size can be solved, and the solution is 128 compatible with SRv6. 130 2. Terminology 132 This document makes use of the terms defined in [RFC8754], [RFC8402] 133 and [RFC8200], and the reader is assumed to be familiar with that 134 terminology. This document introduces the following terms: 136 Compressible SRv6 SID: It is the 128-bit SRv6 SID whose format can be 137 compressed. It is composed by Common Prefix and Generalized Segment 138 Identifier (G-SID) and optional arguments and padding. 140 Common Prefix: It is the same prefix shared by multiple SIDs. 142 G-SRv6: Generalized SRv6 Network Programming 143 G-SRH: Generalized Segment Routing Header. It keeps the same format 144 and code point with original SRH, which can carry multiple G-SIDs and 145 original SIDs. 147 G-SID: Generalized Segment Identifier.It is a Compressed SID(C-SID) 148 [I-D.filsfilscheng-spring-srv6-srh-compression]. 150 G-SID Container: Generalized Segment Identifier Container.It is a 151 C-SID container [I-D.filsfilscheng-spring-srv6-srh-compression]. 153 2.1. Requirements Language 155 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 156 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 157 "OPTIONAL" in this document are to be interpreted as described in BCP 158 14 [RFC2119] [RFC8174] when, and only when, they appear in all 159 capitals, as shown here. 161 3. Concepts of G-SRv6 163 This section describes the concepts of G-SRv6. 165 3.1. G-SID 167 In an SRv6 domain, the SIDs are allocated from an address block, 168 called SID space. Therefore, the SIDs allocated from the same SID 169 space share the common prefix. Also, if the length of the SID is 170 less than 128 bits, then padding is required. In an SID List, the 171 common prefix and padding are redundant. Reducing the redundant 172 information can reduce the overhead of SRv6. 174 This document defines a Generalized SID (G-SID) to carry the 175 different part of the original SRv6 SID in the SRH to reduce the size 176 of the SRH. The G-SID can be a 32-bits value following the common 177 prefix in the original SRv6 SID. An SRv6 SID with this format is 178 called compressible SRv6 SID. The format of a compressible SRv6 SID 179 with 32-bits G-SID is shown in Figure 1. 181 0 Variable Length 32 bits 128 bits 182 +--------------------------------------------------------------+ 183 | Common Prefix | G-SID | Args/padding | 184 +--------------------------------------------------------------+ 185 |<-------- Locator ----------------->| 187 Figure 1. 32 bits G-SID in SRv6 SID 189 In order to indicate the format of the SRv6 SID is compressible, 190 control plane extension may be considered. This is out of scope of 191 this document, and can be described in other documents. 193 3.2. G-SID Container 195 In order to align with 128 bits, a 128 bit G-SID Container is 196 defined. A G-SID Container is a 128 bits value, and it may contain 197 different type of SIDs: 199 o an SRv6 SID: A G-SID Container contains a single SRv6 SID. 201 o A Micro SID Carrier: A G-SID Container contains a Micro SID 202 carrier [I-D.filsfils-spring-net-pgm-extension-srv6-usid]. 204 o Multiple G-SIDs: A G-SID Container contains multiple G-SIDs and 205 optional padding. When G-SID is a 32-bits value, a G-SID 206 Container can consist of 4 G-SIDs. If the length of G-SIDs in a 207 G-SID Container is less than 128 bits, then padding is required. 209 0 1 2 3 210 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 1 211 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 212 | G-SID 0 | 213 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 214 | G-SID 1 | 215 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 216 | G-SID 2 | 217 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 218 | G-SID 3 | 219 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 220 (a) 222 0 1 2 3 223 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 1 224 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 225 | Padding | 226 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 227 | Padding | 228 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 229 | G-SID 0 | 230 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 231 | G-SID 1 | 232 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 233 (b) 235 Figure 2. G-SID Container for Compression 237 3.3. G-SID Index 239 In order to locate the G-SID within the G-SID Container, this section 240 defines Generalized SID Index (SI) to indicate the location of the 241 G-SID within the current G-SID Container. 243 SI is a location argument of the G-SID, which is the least bits in 244 the argument part. When G-SID is a 32 bits value, the SI is the 245 least 2 bits in Argument. 247 0 Variable Length 32 bits 128 bits 248 +--------------------------------------------------------------+ 249 | Common Prefix | G-SID |SI| Padding | 250 +--------------------------------------------------------------+ 252 Figure 4. SI in the IPv6 DA 254 3.4. COC Flavor 256 In order to indicate the SRv6 compression processing, updating the 257 next 32-bits G-SID to the IPv6 DA, this section defines COC(Continue 258 of Compression) Flavor. 260 When a node receives an SID with COC Flavor, it indicates to update 261 the G-SID part in IPv6 DA with the next 32 bits G-SID. 263 When a node receives an SID without COC Flavor, the node processes 264 the packet as a normal SRv6 packet [RFC8986], for example, update the 265 IPv6 DA with the next 128 bits SID if SL >0. 267 Therefore, if the behavior of the last G-SID in the G-SID list has no 268 COC Flavor, then the next 128 bits SID will be updated to the DA, so 269 it indicates the end of the compression sub-path. 271 When COC Flavor applies to END, END.X and END.T, the SIDs can be 272 advertised via the IS-IS [I-D.ietf-lsr-isis-srv6-extensions], and the 273 SRv6 SID Structure Sub-Sub-TLV MUST be carried to indicate the format 274 of the SRv6 SID. The Locator.Block length indicates the length of 275 the common prefix, and the G-SID is the following 32-bits value after 276 the Block, which contains the Node ID and Function ID. 278 4. G-SRH 280 G-SRH supports to encode different types of segment in a single SRH 281 without modifying the encapsulation format of SRH. 283 When an SRv6 path travels normal SRv6 nodes and compressed SRv6 284 nodes, the SRv6 SID and G-SIDs can be encoded in a single G-SRH. 286 For easier understanding, this document assumes that the Compressible 287 SRv6 SID consists of 64 bits common prefix and 32 bits G-SID. The 288 encoding can be shown as follows. 290 0 1 2 3 291 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 1 292 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 293 | Next Header | Hdr Ext Len | Routing Type | Segments Left| 294 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 295 | Last Entry | Flag | Tag | 296 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 297 | Other G-SID Container | 298 . ... . 299 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ --- 300 | Optional Padding | 301 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 302 | G-SID 0 | G-SID Container 0 303 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 304 . ... . ... 305 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 306 | G-SID 3 | 307 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ --- 308 | G-SID 0 | 309 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 310 | G-SID 1 | 311 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 312 | G-SID 2 | G-SID Container j 313 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 314 | G-SID 3 | 315 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ --- 316 | Common Prefix | 317 | | 318 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ G-SID Container k 319 | G-SID 0 | 320 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 321 | Padding | 322 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ --- 323 | ... | 324 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 325 | | 326 | Generalized Segment List[n] (128 bits SRv6 SID) | 327 | | 328 | | 329 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 330 // Optional Type Length Value objects (variable) // 331 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 333 Figure 3. G-SRH for SRv6 Compression 335 Where: 337 o Common Prefix: the common prefix shared by the Compressible SRv6 338 SIDs in the current compression sub-path. Usually, it is the 339 prefix of the SID space, called Locator Block in control plane 340 [RFC8986]. Operators are free to configure the length and the 341 value of the common prefix based on the address planning of their 342 networking. 344 o G-SID: 32-bits Generalized SID. 346 o Padding: Must be zero. When the length of G-SIDs within the G-SID 347 Container is less than 128 bits, then padding is needed. 349 5. Packet Processing 351 This section describes the pseudo code of COC Flavor, and it replaces 352 the S13 and S14 of End, End.X, and End.T's pseudo code [RFC8986]. 353 The pseudo code is shown below. 355 When N receives a packet whose IPv6 DA is S and S is a local SID with 356 COC Flavor, N does: 358 1. If (DA.SI != 0) { //ref1 359 2. Decrement DA.SI by 1. 360 3. } Else { 361 4. Decrement Segments Left by 1. 362 5. Set DA.SI to 3 in the IPv6 Destination Address 363 6. } 364 7. Copy Segment List[Segments Left][DA.SI] into the bits //ref2 365 [B..B+31] of the IPv6 Destination Address. 367 o Ref1: an SID with COC flavor indicates the SRv6 compression 368 processing that the node needs to update the next 32 bits G-SID to 369 the IPv6 DA. 371 * When the SI is greater than 0, the next G-SID is the next G-SID 372 in the current G-SID Container. 374 * Otherwise, the next G-SID is the first G-SID in the next G-SID 375 Container. 377 o Ref2: B is the length of the Locator Block [RFC8986]. 379 An SID without COC Flavor will be processed following the SRv6 380 processing. The node will update the next 128 bit SID to the IPv6 DA 381 if the SL > 0. 383 6. Illustration 385 This section describes a simple example of G-SRv6 for compression. 387 The reference topology is shown below. 389 *--------------------* 390 * SRv6 Domain * 391 * * 392 Tenant10 CE1--0-1-2-3-4-5-6-7-8-9-10--CE2 Tenant10 393 * * 394 *--------------------* 396 Figure 5. Reference topology 398 Nodes 0 - 10 are G-SRv6 enabled nodes within the SRv6 domain, and 399 node 0 is the ingress node of the G-SRv6 path while the node 10 is 400 the egress node. 402 Nodes CE1 and CE2 are tenants of VPN 10, and they are outside of the 403 SRv6 domain. 405 In order to ease the reading of the example, this section introduces 406 a simplified SID allocation schema. 408 o 2001:db8::/64 is dedicated to the internal SRv6 SID space, which 409 is the common prefix for the SIDs as well. 411 o Node k has 2001:db8:0:0:k::/80 for its local SID space. Its SIDs 412 will be explicitly allocated from that block. 414 o 2001:db8:0:0:k:1:: represents the End.X SID with COC allocated by 415 node K, and it is associated with interface N of node K. For 416 instance, 2001:db8:0:0:1:1:: represents the End.X with COC flavor 417 allocated by node 1. 419 o 2001:db8:0:0:k:2:: represents the End.X SID without COC allocated 420 by node K, and it is associated with interface N of node K. For 421 instance, 2001:db8:0:0:1:2:: represents the End.X without COC 422 flavor allocated by node 1. 424 o 2001:db8:0:0:10:10:: is an END.DT4 SID initiated by node 10, which 425 is associated with the VRF10. 427 Therefore, the SID 2001:db8:0:0:1:1::, 2001:db8:0:0:2:1::, 428 2001:db8:0:0:3:1::, 2001:db8:0:0:4:1::, 2001:db8:0:0:5:1::, 429 2001:db8:0:0:6:1::, 2001:db8:0:0:7:1::, 2001:db8:0:0:8:1:: are SRv6 430 End.X SIDs with COC Flavor, and 2001:db8:0:0:9:2:: is a Compressible 431 SRv6 End.X SID. 433 The SID list [2001:db8:0:0:1:1::, 2001:db8:0:0:2:1::, 434 2001:db8:0:0:3:1::, 2001:db8:0:0:4:1::, 2001:db8:0:0:5:1::, 435 2001:db8:0:0:6:1::, 2001:db8:0:0:7:1::, 2001:db8:0:0:8:1::, 436 2001:db8:0:0:9:2::, 2001:db8:0:0:10:10::] is calculated for a strict 437 TE path from Node 1 to Node 10 for the VPN traffic of tenant 10. 439 In G-SRv6, the SID list can be encoded as [2:1, 3:1, 4:1, 5:1, 6:1, 440 7:1, 8:1, 9:2, 2001:db8:0:0:10:10::] in reduced mode. The G-SID 441 Container encoding is shown below. 443 0 1 2 3 444 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 1 445 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ---- 446 | | 447 | 2001:db8:0:0:10:10:: | G-SID Container 0 448 | | 449 | | 450 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ---- 451 | 9:2 | 452 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 453 | 8:1 | 454 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ G-SID Container 1 455 | 7:1 | 456 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 457 | 6:1 | 458 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ---- 459 | 5:1 | 460 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 461 | 4:1 | 462 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ G-SID Container 2 463 | 3:1 | 464 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 465 | 2:1 | 466 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ---- 468 Figure 6. G-SID Container Encoding for G-SRv6 470 The packets forwarding procedures: 472 o Node 0 sends the SRv6 packet with G-SRH to the node 1.The SL is 3. 473 The Active SID in IPv6 DA is 2001:db8:0:0:1:1::. 475 o When node 1 receives the packet, the IPv6 DA is 476 2001:db8:0:0:1:1::, which is a Local End.X with COC Flavor SID. 478 The SRH.SL is 3, and DA.SI is 0. The node processes the packet: 479 SL = SL-1,DA.SI =3, pointing to the next G-SID 2:1, and updates 480 SRH[SL=2][DA.SI=3] to the IPv6 DA[CP:CP+31], where CP is the 481 length of the common prefix. The packet is forwarded with the new 482 IPv6 DA 2001:db8:0:0:2:1:C::, to the node 2. 484 o When node 2 receives the packet, the IPv6 DA is 485 2001:db8:0:0:2:1:C::, which is a Local End.X with COC Flavor SID. 486 The SRH.SL is 2, and DA.SI is 3. The node processes the packet: 487 DA.SI --, pointing to the next G-SID 3:1, and updates 488 SRH[SL=2][DA.SI=2] to the IPv6 DA[CP:CP+31]. The packet is 489 forwarded with the new IPv6 DA 2001:db8:0:0:3:1:8::, to the node 490 3. 492 o Similar to node 1 and 2, the node 3,4,5,6,7,8 process the packet 493 and forward with the new IPv6 DA. 495 o When node 9 receives the packet, the IPv6 DA is 496 2001:db8:0:0:9:2::, which is a Local End.X SID. The SRH.SL is 1. 497 The node updates the next SID 2001:db8:0:0:10:10:: to the IPv6 DA 498 and forwards the packet to the node 10. 500 o Node 10 receives the packet, and the IPv6 DA is an VPN SID 501 allocated by itself, the node processes the SRv6 VPN SID. 503 This illustration shows that 70 % overhead of SID list is removed in 504 G-SRv6(10 x 16 Bytes to 3 x 16 Bytes), also, it shows the 505 capabilities of encoding G-SIDs and SRv6 SIDs in a single G-SRH. 507 7. Benefits 509 o G-SRv6 is fully compatible with SRv6 511 * No SRH encapsulation modification. 513 * No new address consumption: Compressible SRv6 SIDs can be 514 allocated from the Locator allocated to the node. 516 * No new route advertisements: Compressible SRv6 SIDs can share 517 the same locator with the normal SRv6 SID. 519 * No security policy modification: when reusing the Locator with 520 SRv6 SIDs, no security policy need to be updated. 522 * No control plane modification: Controller can install the SR 523 policy with 128-bits G-SID Containers, and the ingress treats 524 the G-SID Container as an opaque 128-bits SID without 525 understanding the structure of it. G-SRv6 capable nodes 526 understand the COC flavor behaviors, while Compression disable 527 SRv6 nodes are unaware of Compression. 529 o G-SRv6 reduces the SRv6 encapsulation size. 531 * 128 bits to 32 bits, up to 75 % overhead is reduced. More 532 overhead is reduced when the G-SID is a 16-bits value. 534 o G-SRv6 has efficient address consumption and easy to deploy 536 * Operators are free to allocate an SID space from their address 537 space. 539 * No affect of networking(i.e. routes and ACL security policies) 540 by using the existing Locator to allocate compressible SRv6 541 SIDs. 543 o G-SRv6 is hardware friendly 545 * Same SRv6 processing flow with a new IPv6 DA update method 547 * Leverages the mature hardware capabilities (DA update, DA 548 longest match) 550 * Avoids extra lookup in indexed mapping table 552 o G-SRv6 supports incremental deployments, which can be deployed on 553 demand. 555 8. Running Code 557 8.1. Interop-test Status 559 The G-SRv6 mechanism has been implemented on the following 10+ 560 hardware devices, software implementations and SDN controllers. 562 They had also successfully participated in the series of joint 563 interoperability testing events hosted by China Mobile from June 2020 564 to November 2020. 566 The following hardware devices and software implementations had 567 successfully passed the series of G-SRv6 dataplane interoperability 568 testing (in alphabetical order). 570 o Chipsets 572 * Broadcom Jericho 2 BCM88690 573 * Centec CTC7132 575 * Intel Barefoot Tofino BFN-T10 577 * Marvell Falcon 98CX8580 579 o Devices 581 * Cisco ASR 9000 583 * Cisco IOS XRv9000 585 * Huawei NE40E 587 * Huawei NE5000E 589 * H3C CR16010H-FA 591 * H3C CR19000-8 593 * Ruijie F9300 Switch 595 * ZTE M6000-8S Plus 597 * ZTE M6000-3S 599 o Test Equipment 601 * IXIA XGS12 603 * Spirent TestCenter N4U 605 The following hardware devices and software implementations had 606 successfully passed the series of G-SRv6 with control plane 607 interoperability test (in alphabetical order). 609 o China Unitechs Unified Controller 611 o Huawei NE40E and NE5000E 613 o H3C CR16010H-FA and CR19000-8 615 o Spirent TestCenter N4U 617 o ZTE M6000-8S Plus and M6000-3S 619 Regarding open-source implementations, G-SRv6 has been implemented on 620 Linux Kernel. 622 8.2. Deployment Status 624 In addition, China Mobile had come up with China Unitechs, Huawei, 625 ZTE and H3C to successfully deploy trial of G-SRv6 (with control 626 plane) in their three province branch networks in November 2020, 627 respectively. 629 The details are listed below (in alphabetical order). 631 o Huawei devices with a China Unitechs Unified Controller, Guangdong 632 Province. L3VPN over G-SRv6 BGP TE policy. 634 o H3C devices with a China Unitechs Unified Controller, Zhejiang 635 Province. L3VPN over G-SRv6 BGP TE policy. 637 o ZTE devices with a China Unitechs Unified Controller, Henan 638 Province. L3VPN over G-SRv6 BGP TE policy. 640 More information of G-SRv6 interop-test and deployment status will be 641 updated as the work progresses. 643 9. Protocol Extensions Requirements 645 This section describes the protocol extension requirements. 647 9.1. Data Plane 649 REQ1-01: An SRv6 compression path can be represented as a G-SID 650 Container list consists of a compressible SRv6 SID and G-SID 651 Containers. 653 REQ1-02: A G-SID Container consists of at most 4 (32-bits) G-SIDs, if 654 the number of G-SID is less than 4, then padding is required to align 655 with 128 bits. 657 REQ1-03: If the first Compressible SRv6 SID is copied to the IPv6 DA, 658 then following G-SIDs should be updated to the IPv6 DA by the nodes 659 along the SRv6 compression sub-path accordingly. 661 REQ1-04: The last G-SID in the G-SID Container for the SRv6 662 compression sub-path is the a G-SID without COC flavor. 664 REQ1-05: When process the G-SID with COC flavor in the IPv6 DA, the 665 next G-SID is updated to the IPv6 DA. 667 9.2. Control Plane 669 REQ1-11: ISIS/OSPF/BGP-LS/PCEP extensions for advertising the 670 capabilities of supporting G-SRv6 for SRv6 compression. 672 REQ1-12: ISIS/OSPF/BGP-LS/BGP extensions for advertising Compressible 673 SRv6 SIDs. 675 REQ1-13: ISIS/OSPF/BGP-LS/BGP extensions for advertising the 676 Continue-of-compression(COC) flavor SID. 678 REQ1-21: BGP SR Policy extensions for programming a G-SRv6 path 679 combining with Compressible SRv6 SIDs and SRv6 SIDs. 681 REQ1-31: PCEP SR Policy extensions for programming a G-SRv6 path 682 combining with G-SIDs and SRv6 SIDs. 684 REQ1-32: PCEP extensions for programming a G-SRv6 path combining with 685 G-SIDs and SRv6 SIDs. 687 10. IANA Considerations 689 This document requests IANA to allocate the following codepoints for 690 COC flavor behaviors within the "SRv6 Endpoint Behaviors" sub- 691 registry under the top-level "Segment Routing Parameters" registry. 693 +-------+--------+----------------------------+-----------+ 694 | Value | Hex | Endpoint behavior | Reference | 695 +-------+--------+----------------------------+-----------+ 696 | 101 | 0x0065 | End with COC | [This.ID] | 697 | 102 | 0x0066 | End with PSP&COC | [This.ID] | 698 | 104 | 0x0068 | End with PSP&USP&COC | [This.ID] | 699 | 105 | 0x0069 | End.X with COC | [This.ID] | 700 | 106 | 0x006A | End.X with PSP&COC | [This.ID] | 701 | 108 | 0x006C | End.X with PSP&USP&COC | [This.ID] | 702 | 109 | 0x006D | End.T with COC | [This.ID] | 703 | 110 | 0x006E | End.T with PSP&COC | [This.ID] | 704 | 112 | 0x0070 | End.T with PSP&USP&COC | [This.ID] | 705 | 130 | 0x0082 | End with PSP&USD&COC | [This.ID] | 706 | 131 | 0x0083 | End with PSP&USP&USD&COC | [This.ID] | 707 | 133 | 0x0085 | End.X with PSP&USD&COC | [This.ID] | 708 | 135 | 0x0087 | End.X with PSP&USP&USD&COC | [This.ID] | 709 | 137 | 0x0089 | End.T with PSP&USD&COC | [This.ID] | 710 | 139 | 0x008B | End.T with PSP&USP&USD&COC | [This.ID] | 711 +-------+--------+----------------------------+-----------+ 712 Table 1: IETF - SRv6 Endpoint Behaviors 714 11. Security Considerations 716 The security considerations described in [RFC8754], and [RFC8402] are 717 applicable to this specification. No additional security measure is 718 required. 720 12. Contributors 722 TBD 724 13. Acknowledgements 726 TBD 728 14. References 730 14.1. Normative References 732 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 733 Requirement Levels", BCP 14, RFC 2119, 734 DOI 10.17487/RFC2119, March 1997, 735 . 737 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 738 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 739 May 2017, . 741 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 742 (IPv6) Specification", STD 86, RFC 8200, 743 DOI 10.17487/RFC8200, July 2017, 744 . 746 [RFC8754] Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J., 747 Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header 748 (SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020, 749 . 751 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., 752 Decraene, B., Litkowski, S., and R. Shakir, "Segment 753 Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, 754 July 2018, . 756 [RFC8986] Filsfils, C., Ed., Camarillo, P., Ed., Leddy, J., Voyer, 757 D., Matsushima, S., and Z. Li, "Segment Routing over IPv6 758 (SRv6) Network Programming", RFC 8986, 759 DOI 10.17487/RFC8986, February 2021, 760 . 762 [I-D.filsfilscheng-spring-srv6-srh-compression] 763 Cheng, W., Filsfils, C., Li, Z., Decraene, B., Cai, D., 764 Voyer, D., Clad, F., Zadok, S., Guichard, J. N., Aihua, 765 L., Raszuk, R., and C. Li, "Compressed SRv6 Segment List 766 Encoding in SRH", draft-filsfilscheng-spring-srv6-srh- 767 compression-02 (work in progress), July 2021. 769 14.2. Informative References 771 [I-D.filsfils-spring-net-pgm-extension-srv6-usid] 772 Filsfils, C., Garvia, P. C., Cai, D., Voyer, D., Meilik, 773 I., Patel, K., Henderickx, W., Jonnalagadda, P., Melman, 774 D., Liu, Y., and J. Guichard, "Network Programming 775 extension: SRv6 uSID instruction", draft-filsfils-spring- 776 net-pgm-extension-srv6-usid-11 (work in progress), 777 September 2021. 779 [I-D.ietf-spring-compression-requirement] 780 Cheng, W., Xie, C., Bonica, R., Dukes, D., Li, C., Shaofu, 781 P., and W. Henderickx, "Compressed SRv6 SID List 782 Requirements", draft-ietf-spring-compression- 783 requirement-00 (work in progress), September 2021. 785 [I-D.ietf-lsr-isis-srv6-extensions] 786 Psenak, P., Filsfils, C., Bashandy, A., Decraene, B., and 787 Z. Hu, "IS-IS Extensions to Support Segment Routing over 788 IPv6 Dataplane", draft-ietf-lsr-isis-srv6-extensions-18 789 (work in progress), October 2021. 791 Authors' Addresses 793 Weiqiang Cheng (editor) 794 China Mobile 795 No.32 Xuanwumen west street 796 Beijing 100053 797 China 799 Email: chengweiqiang@chinamobile.com 801 Zhenbin Li 802 Huawei Technologies 803 Huawei Campus, No. 156 Beiqing Rd. 804 Beijing 100095 805 China 807 Email: lizhenbin@huawei.com 808 Cheng Li (editor) 809 Huawei Technologies 810 Huawei Campus, No. 156 Beiqing Rd. 811 Beijing 100095 812 China 814 Email: c.l@huawei.com 816 Francois Clad 817 Cisco Systems, Inc 818 France 820 Email: fclad@cisco.com 822 Aihua Liu 823 ZTE Corporation 824 Shenzhen 825 China 827 Email: liu.aihua@zte.com.cn 829 Chongfeng Xie 830 China Telecom 831 Technology Innovation park, Changping District 832 Beijing 833 China 835 Email: xiechf@chinatelecom.cn 837 Yisong Liu 838 China Mobile 839 No.32 Xuanwumen west street 840 Beijing 842 Email: liuyisong@chinamobile.com 844 Shay Zadok 845 Broadcom 846 Israel 848 Email: shay.zadok@broadcom.com