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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references to lower-maturity documents in RFCs) ** Downref: Normative reference to an Informational RFC: RFC 7665 == Outdated reference: A later version (-07) exists of draft-guichard-sfc-nsh-dc-allocation-05 == Outdated reference: A later version (-13) exists of draft-ietf-nvo3-vxlan-gpe-04 == Outdated reference: A later version (-15) exists of draft-ietf-sfc-oam-framework-02 == Outdated reference: A later version (-04) exists of draft-napper-sfc-nsh-broadband-allocation-02 Summary: 1 error (**), 0 flaws (~~), 5 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Service Function Chaining P. Quinn, Ed. 3 Internet-Draft Cisco 4 Intended status: Standards Track U. Elzur, Ed. 5 Expires: January 20, 2018 Intel 6 C. Pignataro, Ed. 7 Cisco 8 July 19, 2017 10 Network Service Header (NSH) 11 draft-ietf-sfc-nsh-16 13 Abstract 15 This document describes a Network Service Header (NSH) inserted onto 16 packets or frames to realize service function paths. NSH also 17 provides a mechanism for metadata exchange along the instantiated 18 service paths. NSH is the SFC encapsulation required to support the 19 Service Function Chaining (SFC) architecture (defined in RFC7665). 21 Status of This Memo 23 This Internet-Draft is submitted in full conformance with the 24 provisions of BCP 78 and BCP 79. 26 Internet-Drafts are working documents of the Internet Engineering 27 Task Force (IETF). Note that other groups may also distribute 28 working documents as Internet-Drafts. The list of current Internet- 29 Drafts is at http://datatracker.ietf.org/drafts/current/. 31 Internet-Drafts are draft documents valid for a maximum of six months 32 and may be updated, replaced, or obsoleted by other documents at any 33 time. It is inappropriate to use Internet-Drafts as reference 34 material or to cite them other than as "work in progress." 36 This Internet-Draft will expire on January 20, 2018. 38 Copyright Notice 40 Copyright (c) 2017 IETF Trust and the persons identified as the 41 document authors. All rights reserved. 43 This document is subject to BCP 78 and the IETF Trust's Legal 44 Provisions Relating to IETF Documents 45 (http://trustee.ietf.org/license-info) in effect on the date of 46 publication of this document. Please review these documents 47 carefully, as they describe your rights and restrictions with respect 48 to this document. Code Components extracted from this document must 49 include Simplified BSD License text as described in Section 4.e of 50 the Trust Legal Provisions and are provided without warranty as 51 described in the Simplified BSD License. 53 Table of Contents 55 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 56 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 57 1.2. Definition of Terms . . . . . . . . . . . . . . . . . . . 4 58 1.3. Problem Space . . . . . . . . . . . . . . . . . . . . . . 4 59 1.4. NSH-based Service Chaining . . . . . . . . . . . . . . . 5 60 2. Network Service Header . . . . . . . . . . . . . . . . . . . 5 61 2.1. Network Service Header Format . . . . . . . . . . . . . . 6 62 2.2. NSH Base Header . . . . . . . . . . . . . . . . . . . . . 6 63 2.3. Service Path Header . . . . . . . . . . . . . . . . . . . 9 64 2.4. NSH MD Type 1 . . . . . . . . . . . . . . . . . . . . . . 10 65 2.5. NSH MD Type 2 . . . . . . . . . . . . . . . . . . . . . . 11 66 2.5.1. Optional Variable Length Metadata . . . . . . . . . . 11 67 3. NSH Actions . . . . . . . . . . . . . . . . . . . . . . . . . 13 68 4. NSH Transport Encapsulation . . . . . . . . . . . . . . . . . 14 69 5. Fragmentation Considerations . . . . . . . . . . . . . . . . 15 70 6. Service Path Forwarding with NSH . . . . . . . . . . . . . . 15 71 6.1. SFFs and Overlay Selection . . . . . . . . . . . . . . . 15 72 6.2. Mapping NSH to Network Transport . . . . . . . . . . . . 18 73 6.3. Service Plane Visibility . . . . . . . . . . . . . . . . 19 74 6.4. Service Graphs . . . . . . . . . . . . . . . . . . . . . 19 75 7. Policy Enforcement with NSH . . . . . . . . . . . . . . . . . 19 76 7.1. NSH Metadata and Policy Enforcement . . . . . . . . . . . 19 77 7.2. Updating/Augmenting Metadata . . . . . . . . . . . . . . 21 78 7.3. Service Path Identifier and Metadata . . . . . . . . . . 23 79 8. Security Considerations . . . . . . . . . . . . . . . . . . . 23 80 9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 24 81 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 26 82 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 27 83 11.1. NSH EtherType . . . . . . . . . . . . . . . . . . . . . 27 84 11.2. Network Service Header (NSH) Parameters . . . . . . . . 27 85 11.2.1. NSH Base Header Unassigned Bits . . . . . . . . . . 27 86 11.2.2. NSH Version . . . . . . . . . . . . . . . . . . . . 27 87 11.2.3. MD Type Registry . . . . . . . . . . . . . . . . . . 28 88 11.2.4. MD Class Registry . . . . . . . . . . . . . . . . . 28 89 11.2.5. NSH Base Header Next Protocol . . . . . . . . . . . 29 90 11.2.6. New IETF assigned MD Type Registry . . . . . . . . . 29 91 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 30 92 12.1. Normative References . . . . . . . . . . . . . . . . . . 30 93 12.2. Informative References . . . . . . . . . . . . . . . . . 30 94 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 31 96 1. Introduction 98 Service functions are widely deployed and essential in many networks. 99 These service functions provide a range of features such as security, 100 WAN acceleration, and server load balancing. Service functions may 101 be instantiated at different points in the network infrastructure 102 such as the wide area network, data center, campus, and so forth. 104 Prior to development of the SFC architecture [RFC7665] and the 105 protocol specified in this document, current service function 106 deployment models have been relatively static, and bound to topology 107 for insertion and policy selection. Furthermore, they do not adapt 108 well to elastic service environments enabled by virtualization. 110 New data center network and cloud architectures require more flexible 111 service function deployment models. Additionally, the transition to 112 virtual platforms requires an agile service insertion model that 113 supports dynamic and elastic service delivery; the movement of 114 service functions and application workloads in the network and the 115 ability to easily bind service policy to granular information such as 116 per-subscriber state and steer traffic to the requisite service 117 function(s) are necessary. 119 Network Service Header (NSH) defines a new service plane protocol 120 specifically for the creation of dynamic service chains and is 121 composed of the following elements: 123 1. Service Function Path identification. 125 2. Indication of location within a Service Function Path. 127 3. Optional, per packet metadata (fixed length or variable). 129 NSH is designed to be easy to implement across a range of devices, 130 both physical and virtual, including hardware platforms. 132 An NSH-aware control plane is outside the scope of this document. 134 [RFC7665] provides an overview of a service chaining architecture 135 that clearly defines the roles of the various elements and the scope 136 of a service function chaining encapsulation. NSH is the SFC 137 encapsulation referenced in [RFC7665]. 139 1.1. Requirements Language 141 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 142 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 143 document are to be interpreted as described in RFC 2119 [RFC2119]. 145 1.2. Definition of Terms 147 Byte: All references to "bytes" in this document refer to 8-bit 148 bytes, or octets. 150 Classification: Defined in [RFC7665]. 152 Classifier: Defined in [RFC7665]. 154 Metadata: Defined in [RFC7665]. 156 Network Locator: dataplane address, typically IPv4 or IPv6, used to 157 send and receive network traffic. 159 Network Node/Element: Device that forwards packets or frames based 160 on an outer header (i.e., transport) information. 162 Network Overlay: Logical network built on top of existing network 163 (the underlay). Packets are encapsulated or tunneled to create 164 the overlay network topology. 166 Service Classifier: Logical entity providing classification 167 function. Since they are logical, classifiers may be co-resident 168 with SFC elements such as SFs or SFFs. Service classifiers 169 perform classification and impose NSH. The initial classifier 170 imposes the initial NSH and sends the NSH packet to the first SFF 171 in the path. Non-initial (i.e. subsequent) classification can 172 occur as needed and can alter, or create a new service path. 174 Service Function (SF): Defined in [RFC7665]. 176 Service Function Chain (SFC): Defined in [RFC7665]. 178 Service Function Forwarder (SFF): Defined in [RFC7665]. 180 Service Function Path (SFP): Defined in [RFC7665]. 182 SFC Proxy: Defined in [RFC7665]. 184 1.3. Problem Space 186 NSH addresses several limitations associated with service function 187 deployments. [RFC7498] provides a comprehensive review of those 188 issues. 190 1.4. NSH-based Service Chaining 192 NSH creates a dedicated service plane, more specifically, NSH 193 enables: 195 1. Topological Independence: Service forwarding occurs within the 196 service plane, the underlying network topology does not require 197 modification. NSH provides an identifier used to select the 198 network overlay for network forwarding. 200 2. Service Chaining: NSH enables service chaining per [RFC7665]. 201 NSH contains path identification information needed to realize a 202 service path. Furthermore, NSH provides the ability to monitor 203 and troubleshoot a service chain, end-to-end via service-specific 204 OAM messages. NSH fields can be used by administrators (via, for 205 example, a traffic analyzer) to verify (account, ensure correct 206 chaining, provide reports, etc.) the path specifics of packets 207 being forwarded along a service path. 209 3. NSH provides a mechanism to carry shared metadata between 210 participating entities and service functions. The semantics of 211 the shared metadata is communicated via a control plane, which is 212 outside the scope of this document, to participating nodes. 213 [I-D.ietf-sfc-control-plane] provides an example of such in 214 Section 3.3. Examples of metadata include classification 215 information used for policy enforcement and network context for 216 forwarding post service delivery. Sharing the metadata allows 217 service functions to share initial and intermediate 218 classification results with downstream service functions saving 219 re-classification, where enough information was enclosed. 221 4. NSH offers a common and standards-based header for service 222 chaining to all network and service nodes. 224 5. Transport Agnostic: NSH is transport-independent. An appropriate 225 (for a given deployment) network transport protocol can be used 226 to transport NSH-encapsulated traffic. This transport may form 227 an overlay network and if an existing overlay topology provides 228 the required service path connectivity, that existing overlay may 229 be used. 231 2. Network Service Header 233 NSH contains service path information and optionally metadata that 234 are added to a packet or frame and used to create a service plane. 235 An outer transport header is imposed, on NSH and the original packet/ 236 frame, for network forwarding. 238 A Service Classifier adds NSH. NSH is removed by the last SFF in the 239 service chain or by an SF that consumes the packet. 241 2.1. Network Service Header Format 243 NSH is composed of a 4-byte Base Header, a 4-byte Service Path Header 244 and optional Context Headers, as shown in Figure 1 below. 246 0 1 2 3 247 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 1 248 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 249 | Base Header | 250 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 251 | Service Path Header | 252 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 253 | | 254 ~ Context Header(s) ~ 255 | | 256 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 258 Figure 1: Network Service Header 260 Base header: provides information about the service header and the 261 payload protocol. 263 Service Path Header: provides path identification and location within 264 a service path. 266 Context header: carries metadata (i.e., context data) along a service 267 path. 269 2.2. NSH Base Header 271 Figure 2 depicts the NSH base header: 273 0 1 2 3 274 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 1 275 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 276 |Ver|O|U| TTL | Length |U|U|U|U|MD Type| Next Protocol | 277 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 279 Figure 2: NSH Base Header 281 Base Header Field Descriptions: 283 Version: The version field is used to ensure backward compatibility 284 going forward with future NSH specification updates. It MUST be set 285 to 0x0 by the sender, in this first revision of NSH. Given the 286 widespread implementation of existing hardware that uses the first 287 nibble after an MPLS label stack for ECMP decision processing, this 288 document reserves version 01b and this value MUST NOT be used in 289 future versions of the protocol. Please see [RFC7325] for further 290 discussion of MPLS-related forwarding requirements. 292 O bit: Setting this bit indicates an Operations, Administration, and 293 Maintenance (OAM) packet. The actual format and processing of SFC 294 OAM packets is outside the scope of this specification (see for 295 example [I-D.ietf-sfc-oam-framework] for one approach). 297 The O bit MUST be set for OAM packets and MUST NOT be set for non-OAM 298 packets. The O bit MUST NOT be modified along the SFP. 300 SF/SFF/SFC Proxy/Classifier implementations that do not support SFC 301 OAM procedures SHOULD discard packets with O bit set, but MAY support 302 a configurable parameter to enable forwarding received SFC OAM 303 packets unmodified to the next element in the chain. Forwarding OAM 304 packets unmodified by SFC elements that do not support SFC OAM 305 procedures may be acceptable for a subset of OAM functions, but can 306 result in unexpected outcomes for others, thus it is recommended to 307 analyze the impact of forwarding an OAM packet for all OAM functions 308 prior to enabling this behavior. The configurable parameter MUST be 309 disabled by default. 311 TTL: Indicates the maximum SFF hops for an SFP. The initial TTL 312 value SHOULD be configurable via the control plane; the configured 313 initial value can be specific to one or more SFPs. If no initial 314 value is explicitly provided, the default initial TTL value 63 MUST 315 be used. Each SFF involved in forwarding an NSH packet MUST 316 decrement the TTL value by 1 prior to NSH forwarding lookup. 317 Decrementing by 1 from an incoming value of 0 shall result in a TTL 318 value of 63. The packet MUST NOT be forwarded if TTL is, after 319 decrement, 0. 321 All other flag fields are unassigned and available for future use, 322 see Section 11.2.1. Unassigned bits MUST be set to zero upon 323 origination and MUST be preserved unmodified by other NSH supporting 324 elements. Elements which do not understand the meaning of any of 325 these bits MUST NOT modify their actions based on those unknown bits. 327 Length: The total length, in 4-byte words, of NSH including the Base 328 Header, the Service Path Header, the Fixed Length Context Header or 329 Variable Length Context Header(s). The length MUST be of value 0x6 330 for MD Type equal to 0x1, and MUST be of value 0x2 or greater for MD 331 Type equal to 0x2. The length of the NSH header MUST be an integer 332 multiple of 4 bytes, thus variable length metadata is always padded 333 out to a multiple of 4 bytes. 335 MD Type: indicates the format of NSH beyond the mandatory Base Header 336 and the Service Path Header. MD Type defines the format of the 337 metadata being carried. Please see the IANA Considerations 338 Section 11.2.3. 340 This document specifies the following four MD Type values: 342 0x0 - this is a reserved value. Implementations SHOULD silently 343 discard packets with MD Type 0x0. 345 0x1 - which indicates that the format of the header includes a fixed 346 length Context Header (see Figure 4 below). 348 0x2 - which does not mandate any headers beyond the Base Header and 349 Service Path Header, but may contain optional variable length Context 350 Header(s). The semantics of the variable length Context Header(s) 351 are not defined in this document. The format of the optional 352 variable length Context Headers is provided in Section 2.5.1. 354 0xF - this value is reserved for experimentation and testing, as per 355 [RFC3692]. Implementations not explicitly configured to be part of 356 an experiment SHOULD silently discard packets with MD Type 0xF. 358 The format of the Base Header and the Service Path Header is 359 invariant, and not affected by MD Type. 361 NSH implementations MUST support MD type = 0x1 and MD Type = 0x2 362 (where the length is of value 0x2). NSH implementations SHOULD 363 support MD Type 0x2 with length > 0x2. There exists, however, a 364 middle ground, wherein a device will support MD Type 0x1 (as per the 365 MUST) metadata, yet be deployed in a network with MD Type 0x2 366 metadata packets. In that case, the MD Type 0x1 node, MUST utilize 367 the base header length field to determine the original payload offset 368 if it requires access to the original packet/frame. This 369 specification does not disallow the MD Type value from changing along 370 an SFP; however, the specification of the necessary mechanism to 371 allow the MD Type to change along an SFP are outside the scope of 372 this document, and would need to be defined for that functionality to 373 be available. Packets with MD Type values not supported by an 374 implementation MUST be silently dropped. 376 Next Protocol: indicates the protocol type of the encapsulated data. 377 NSH does not alter the inner payload, and the semantics on the inner 378 protocol remain unchanged due to NSH service function chaining. 379 Please see the IANA Considerations section below, Section 11.2.5. 381 This document defines the following Next Protocol values: 383 0x0: Unassigned 384 0x1: IPv4 385 0x2: IPv6 386 0x3: Ethernet 387 0x4: NSH 388 0x5: MPLS 389 0xFE: Experiment 1 390 0xFF: Experiment 2 392 Packets with Next Protocol values not supported SHOULD be silently 393 dropped by default, although an implementation MAY provide a 394 configuration parameter to forward them. Additionally, an 395 implementation not explicitly configured for a specific experiment 396 [RFC3692] SHOULD silently drop packets with Next Protocol values 0xFE 397 and 0xFF. 399 2.3. Service Path Header 401 Figure 3 shows the format of the Service Path Header: 403 0 1 2 3 404 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 1 405 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 406 | Service Path Identifier (SPI) | Service Index | 407 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 409 Service Path Identifier (SPI): 24 bits 410 Service Index (SI): 8 bits 412 Figure 3: NSH Service Path Header 414 The meaning of these fields is as follows: 416 Service Path Identifier (SPI): identifies a service path. 417 Participating nodes MUST use this identifier for Service Function 418 Path selection. The initial classifier MUST set the appropriate SPI 419 for a given classification result. 421 Service Index (SI): provides location within the SFP. The initial 422 classifier for a given SFP SHOULD set the SI to 255, however the 423 control plane MAY configure the initial value of SI as appropriate 424 (i.e., taking into account the length of the service function path). 425 Service Index MUST be decremented by a value of 1 by Service 426 Functions or by SFC Proxy nodes after performing required services 427 and the new decremented SI value MUST be used in the egress NSH 428 packet. The initial Classifier MUST send the packet to the first SFF 429 in the identified SFP for forwarding along an SFP. If re- 430 classification occurs, and that re-classification results in a new 431 SPI, the (re)classifier is, in effect, the initial classifier for the 432 resultant SPI. 434 The SI is used in conjunction with Service Path Identifier for 435 Service Function Path Selection and for determining the next SFF/SF 436 in the path. The SI is also valuable when troubleshooting/ reporting 437 service paths. In addition to indicating the location within a 438 Service Function Path, SI can be used for service plane loop 439 detection. 441 2.4. NSH MD Type 1 443 When the Base Header specifies MD Type = 0x1, a Fixed Length Context 444 Header (16-bytes) MUST be present immediately following the Service 445 Path Header, as per Figure 4. A Fixed Length Context Header that 446 carries no metadata MUST be set to zero. 448 0 1 2 3 449 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 1 450 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 451 |Ver|O|U| TTL | Length |U|U|U|U|MD Type| Next Protocol | 452 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 453 | Service Path Identifier | Service Index | 454 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 455 | | 456 | Fixed Length Context Header | 457 | | 458 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 460 Figure 4: NSH MD Type=0x1 462 This specification does not make any assumptions about the content of 463 the 16 byte Context Header that must be present when the MD Type 464 field is set to 1, and does not describe the structure or meaning of 465 the included metadata. 467 An SFC-aware SF MUST receive the data semantics first in order to 468 process the data placed in the mandatory context field. The data 469 semantics include both the allocation schema and the meaning of the 470 included data. How an SFC-aware SF gets the data semantics is 471 outside the scope of this specification. 473 An SF or SFC Proxy that does not know the format or semantics of the 474 Context Header for an NSH with MD Type 1 MUST discard any packet with 475 such an NSH (i.e., MUST NOT ignore the metadata that it cannot 476 process), and MUST log the event at least once per the SPI for which 477 the event occurs (subject to thresholding). 479 [I-D.guichard-sfc-nsh-dc-allocation] and 480 [I-D.napper-sfc-nsh-broadband-allocation] provide specific examples 481 of how metadata can be allocated. 483 2.5. NSH MD Type 2 485 When the base header specifies MD Type = 0x2, zero or more Variable 486 Length Context Headers MAY be added, immediately following the 487 Service Path Header (see Figure 5). Therefore, Length = 0x2, 488 indicates that only the Base Header followed by the Service Path 489 Header are present. The optional Variable Length Context Headers 490 MUST be of an integer number of 4-bytes. The base header Length 491 field MUST be used to determine the offset to locate the original 492 packet or frame for SFC nodes that require access to that 493 information. 495 0 1 2 3 496 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 1 497 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 498 |Ver|O|U| TTL | Length |U|U|U|U|MD Type| Next Protocol | 499 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 500 | Service Path Identifier | Service Index | 501 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 502 | | 503 ~ Variable Length Context Headers (opt.) ~ 504 | | 505 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 507 Figure 5: NSH MD Type=0x2 509 2.5.1. Optional Variable Length Metadata 511 The format of the optional variable length Context Headers, is as 512 depicted in Figure 6. 514 0 1 2 3 515 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 1 516 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 517 | Metadata Class | Type |U| Len | 518 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 519 | Variable Metadata | 520 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 522 Figure 6: Variable Context Headers 524 Metadata Class (MD Class): defines the scope of the 'Type' field to 525 provide a hierarchical namespace. The IANA Considerations 526 Section 11.2.4 defines how the MD Class values can be allocated to 527 standards bodies, vendors, and others. 529 Type: indicates the explicit type of metadata being carried and is 530 the responsibility of the MD Class owner. 532 Unassigned bit: one unassigned bit is available for future use. This 533 bit MUST be set to 0b. 535 Length: indicates the length of the variable metadata, in single byte 536 words. In case the metadata length is not an integer number of 537 4-byte words, the sender MUST add pad bytes immediately following the 538 last metadata byte to extend the metadata to an integer number of 539 4-byte words. The receiver MUST round up the length field to the 540 nearest 4-byte word boundary, to locate and process the next field in 541 the packet. The receiver MUST access only those bytes in the 542 metadata indicated by the length field (i.e., actual number of single 543 byte words) and MUST ignore the remaining bytes up to the nearest 544 4-byte word boundary. The Length may be 0 or greater. 546 A value of 0 denotes a Context Header without a Variable Metadata 547 field. 549 This specification does not make any assumption about Context Headers 550 that are mandatory-to-implement or those that are mandatory-to- 551 process. These considerations are deployment-specific. However, the 552 control plane is entitled to instruct SFC-aware SFs with the data 553 structure of context header together with their scoping (see 554 Section 3.3.3 of [I-D.ietf-sfc-control-plane]). 556 Upon receipt of a packet that belong to a given SFP, if a mandatory- 557 to-process context header is missing in that packet, the SFC-aware SF 558 MUST NOT process the packet and MUST log at least once per the SPI 559 for which a mandatory metadata is missing. 561 If multiple mandatory-to-process context headers are required for a 562 given SFP, the control plane MAY instruct the SFC-aware SF with the 563 order to consume these Context Headers. If no instructions are 564 provided, the SFC-aware SF MUST process these Context Headers in the 565 order their appear in an NSH packet. 567 If multiple instances of the same metadata are included in an NSH 568 packet, but the definition of that context header does not allow for 569 it, the SFC-aware SF MUST process first instance and ignore 570 subsequent instances. 572 3. NSH Actions 574 NSH-aware nodes are the only nodes that may alter the content of NSH 575 headers. NSH-aware nodes include: service classifiers, SFF, SF and 576 SFC proxies. These nodes have several possible NSH-related actions: 578 1. Insert or remove NSH: These actions can occur at the start and 579 end respectively of a service path. Packets are classified, and 580 if determined to require servicing, NSH will be imposed. A 581 service classifier MUST insert NSH at the start of an SFP. An 582 imposed NSH MUST contain valid Base Header and Service Path 583 Header. At the end of a service function path, an SFF, MUST be 584 the last node operating on the service header and MUST remove NSH 585 before forwarding or delivering the un-encapsulated packet 587 Multiple logical classifiers may exist within a given service 588 path. Non-initial classifiers may re-classify data and that re- 589 classification MAY result in the selection a different Service 590 Function Path. When the logical classifier performs re- 591 classification that results in a change of service path, it MUST 592 remove the existing NSH and MUST impose a new NSH with the Base 593 Header and Service Path Header reflecting the new service path 594 information and set the initial SI. Metadata MAY be preserved in 595 the new NSH. 597 2. Select service path: The Service Path Header provides service 598 path information and is used by SFFs to determine correct service 599 path selection. SFFs MUST use the Service Path Header for 600 selecting the next SF or SFF in the service path. 602 3. Update NSH: SFs MUST decrement the service index by one. If an 603 SFF receives a packet with an SPI and SI that do not correspond 604 to a valid next hop in a valid Service Function Path, that packet 605 MUST be dropped by the SFF. 607 Classifiers MAY update Context Headers if new/updated context is 608 available. 610 If an SFC proxy is in use (acting on behalf of a NSH unaware 611 service function for NSH actions), then the proxy MUST update 612 Service Index and MAY update contexts. When an SFC proxy 613 receives an NSH-encapsulated packet, it MUST remove NSH before 614 forwarding it to an NSH unaware SF. When the SFC Proxy receives 615 a packet back from an NSH unaware SF, it MUST re-encapsulates it 616 with the correct NSH, and MUST decrement the Service Index by 617 one. 619 4. Service policy selection: Service Functions derive policy (i.e., 620 service actions such as permit or deny) selection and enforcement 621 from NSH. Metadata shared in NSH can provide a range of service- 622 relevant information such as traffic classification. 624 Figure 7 maps each of the four actions above to the components in the 625 SFC architecture that can perform it. 627 +----------------+---------------+-------+----------------+---------+ 628 | | Insert |Forward| Update |Service | 629 | | or remove NSH |NSH | NSH |policy | 630 | | |Packets| |selection| 631 | Component +-------+-------+ +----------------+ | 632 | | | | | Dec. |Update | | 633 | |Insert |Remove | |Service |Context| | 634 | | | | | Index |Header | | 635 +----------------+-------+-------+-------+--------+-------+---------+ 636 | | + | + | | | + | | 637 |Classifier | | | | | | | 638 +--------------- +-------+-------+-------+--------+-------+---------+ 639 |Service Function| | + | + | | | | 640 |Forwarder(SFF) | | | | | | | 641 +--------------- +-------+-------+-------+--------+-------+---------+ 642 |Service | | | | + | + | + | 643 |Function (SF) | | | | | | | 644 +--------------- +-------+-------+-------+--------+-------+---------+ 645 |SFC Proxy | + | + | | + | + | | 646 +----------------+-------+-------+-------+--------+-------+---------+ 648 Figure 7: NSH Action and Role Mapping 650 4. NSH Transport Encapsulation 652 Once NSH is added to a packet, an outer encapsulation is used to 653 forward the original packet and the associated metadata to the start 654 of a service chain. The encapsulation serves two purposes: 656 1. Creates a topologically independent services plane. Packets are 657 forwarded to the required services without changing the 658 underlying network topology 660 2. Transit network nodes simply forward the encapsulated packets as 661 is. 663 The service header is independent of the encapsulation used and is 664 encapsulated in existing transports. The presence of NSH is 665 indicated via protocol type or other indicator in the outer 666 encapsulation. 668 5. Fragmentation Considerations 670 NSH and the associated transport header are "added" to the 671 encapsulated packet/frame. This additional information increases the 672 size of the packet. 674 As discussed in [I-D.ietf-rtgwg-dt-encap], within an administrative 675 domain, an operator can ensure that the underlay MTU is sufficient to 676 carry SFC traffic without requiring fragmentation. 678 However, there will be cases where the underlay MTU is not large 679 enough to carry the NSH traffic. Since NSH does not provide 680 fragmentation support at the service plane, the transport/overlay 681 layer MUST provide the requisite fragmentation handling. Section 6 682 of [I-D.ietf-rtgwg-dt-encap] provides guidance for those scenarios. 684 6. Service Path Forwarding with NSH 686 6.1. SFFs and Overlay Selection 688 As described above, NSH contains a Service Path Identifier (SPI) and 689 a Service Index (SI). The SPI is, as per its name, an identifier. 690 The SPI alone cannot be used to forward packets along a service path. 691 Rather the SPI provides a level of indirection between the service 692 path/topology and the network transport. Furthermore, there is no 693 requirement, or expectation of an SPI being bound to a pre-determined 694 or static network path. 696 The Service Index provides an indication of location within a service 697 path. The combination of SPI and SI provides the identification of a 698 logical SF and its order within the service plane, and is used to 699 select the appropriate network locator(s) for overlay forwarding. 700 The logical SF may be a single SF, or a set of eligible SFs that are 701 equivalent. In the latter case, the SFF provides load distribution 702 amongst the collection of SFs as needed. 704 SI serves as a mechanism for detecting invalid service function path. 705 In particular, an SI value of zero indicates that forwarding is 706 incorrect and the packet must be discarded 708 This indirection -- SPI to overlay -- creates a true service plane. 709 That is the SFF/SF topology is constructed without impacting the 710 network topology but more importantly service plane only participants 711 (i.e., most SFs) need not be part of the network overlay topology and 712 its associated infrastructure (e.g., control plane, routing tables, 713 etc.) SFs need to be able to return a packet to an appropriate SFF 714 (i.e., has the requisite NSH information) when service processing is 715 complete. This can be via the over or underlay and in some case 716 require additional configuration on the SF. As mentioned above, an 717 existing overlay topology may be used provided it offers the 718 requisite connectivity. 720 The mapping of SPI to transport occurs on an SFF (as discussed above, 721 the first SFF in the path gets a NSH encapsulated packet from the 722 Classifier). The SFF consults the SPI/ID values to determine the 723 appropriate overlay transport protocol (several may be used within a 724 given network) and next hop for the requisite SF. Table 1 below 725 depicts an example of a single next-hop SPI/SI to network overlay 726 network locator mapping. 728 +------+------+---------------------+-------------------+ 729 | SPI | SI | Next hop(s) | Transport | 730 +------+------+---------------------+-------------------+ 731 | 10 | 255 | 192.0.2.1 | VXLAN-gpe | 732 | | | | | 733 | 10 | 254 | 198.51.100.10 | GRE | 734 | | | | | 735 | 10 | 251 | 198.51.100.15 | GRE | 736 | | | | | 737 | 40 | 251 | 198.51.100.15 | GRE | 738 | | | | | 739 | 50 | 200 | 01:23:45:67:89:ab | Ethernet | 740 | | | | | 741 | 15 | 212 | Null (end of path) | None | 742 +------+------+---------------------+-------------------+ 744 Table 1: SFF NSH Mapping Example 746 Additionally, further indirection is possible: the resolution of the 747 required SF network locator may be a localized resolution on an SFF, 748 rather than a service function chain control plane responsibility, as 749 per Table 2 and Table 3 below. 751 Please note: VXLAN-gpe and GRE in the above table refer to 752 [I-D.ietf-nvo3-vxlan-gpe] and [RFC2784], respectively. 754 +------+-----+----------------+ 755 | SPI | SI | Next hop(s) | 756 +------+-----+----------------+ 757 | 10 | 3 | SF2 | 758 | | | | 759 | 245 | 12 | SF34 | 760 | | | | 761 | 40 | 9 | SF9 | 762 +------+-----+----------------+ 764 Table 2: NSH to SF Mapping Example 766 +------+-------------------+-------------+ 767 | SF | Next hop(s) | Transport | 768 +------+-------------------+-------------+ 769 | SF2 | 192.0.2.2 | VXLAN-gpe | 770 | | | | 771 | SF34 | 198.51.100.34 | UDP | 772 | | | | 773 | SF9 | 2001:db8::1 | GRE | 774 +------+-------------------+-------------+ 776 Table 3: SF Locator Mapping Example 778 Since the SPI is a representation of the service path, the lookup may 779 return more than one possible next-hop within a service path for a 780 given SF, essentially a series of weighted (equally or otherwise) 781 paths to be used (for load distribution, redundancy or policy), see 782 Table 4. The metric depicted in Table 4 is an example to help 783 illustrated weighing SFs. In a real network, the metric will range 784 from a simple preference (similar to routing next- hop), to a true 785 dynamic composite metric based on some service function-centric state 786 (including load, sessions state, capacity, etc.) 787 +------+-----+--------------+---------+ 788 | SPI | SI | NH | Metric | 789 +------+-----+--------------+---------+ 790 | 10 | 3 | 203.0.113.1 | 1 | 791 | | | | | 792 | | | 203.0.113.2 | 1 | 793 | | | | | 794 | 20 | 12 | 192.0.2.1 | 1 | 795 | | | | | 796 | | | 203.0.113.4 | 1 | 797 | | | | | 798 | 30 | 7 | 192.0.2.10 | 10 | 799 | | | | | 800 | | | 198.51.100.1 | 5 | 801 +------+-----+--------------+---------+ 803 (encapsulation type omitted for formatting) 805 Table 4: NSH Weighted Service Path 807 6.2. Mapping NSH to Network Transport 809 As described above, the mapping of SPI to network topology may result 810 in a single path, or it might result in a more complex topology. 811 Furthermore, the SPI to overlay mapping occurs at each SFF 812 independently. Any combination of topology selection is possible. 813 Please note, there is no requirement to create a new overlay topology 814 if a suitable one already existing. NSH packets can use any (new or 815 existing) overlay provided the requisite connectivity requirements 816 are satisfied. 818 Examples of mapping for a topology: 820 1. Next SF is located at SFFb with locator 2001:db8::1 821 SFFa mapping: SPI=10 --> VXLAN-gpe, dst-ip: 2001:db8::1 823 2. Next SF is located at SFFc with multiple network locators for 824 load distribution purposes: 825 SFFb mapping: SPI=10 --> VXLAN-gpe, dst_ip:203.0.113.1, 826 203.0.113.2, 203.0.113.3, equal cost 828 3. Next SF is located at SFFd with two paths from SFFc, one for 829 redundancy: 830 SFFc mapping: SPI=10 --> VXLAN-gpe, dst_ip:192.0.2.10 cost=10, 831 203.0.113.10, cost=20 833 In the above example, each SFF makes an independent decision about 834 the network overlay path and policy for that path. In other words, 835 there is no a priori mandate about how to forward packets in the 836 network (only the order of services that must be traversed). 838 The network operator retains the ability to engineer the network 839 paths as required. For example, the overlay path between SFFs may 840 utilize traffic engineering, QoS marking, or ECMP, without requiring 841 complex configuration and network protocol support to be extended to 842 the service path explicitly. In other words, the network operates as 843 expected, and evolves as required, as does the service plane. 845 6.3. Service Plane Visibility 847 The SPI and SI serve an important function for visibility into the 848 service topology. An operator can determine what service path a 849 packet is "on", and its location within that path simply by viewing 850 NSH information (packet capture, IPFIX, etc.) The information can be 851 used for service scheduling and placement decisions, troubleshooting 852 and compliance verification. 854 6.4. Service Graphs 856 While a given realized service function path is a specific sequence 857 of service functions, the service as seen by a user can actually be a 858 collection of service function paths, with the interconnection 859 provided by classifiers (in-service path, non-initial 860 reclassification). These internal reclassifiers examine the packet 861 at relevant points in the network, and, if needed, SPI and SI are 862 updated (whether this update is a re-write, or the imposition of a 863 new NSH with new values is implementation specific) to reflect the 864 "result" of the classification. These classifiers may also of course 865 modify the metadata associated with the packet. 866 [RFC7665], Section 2.1 describes Service Graphs in detail. 868 7. Policy Enforcement with NSH 870 7.1. NSH Metadata and Policy Enforcement 872 As described in Section 3, NSH provides the ability to carry metadata 873 along a service path. This metadata may be derived from several 874 sources, common examples include: 876 Network nodes/devices: Information provided by network nodes can 877 indicate network-centric information (such as VRF or tenant) that 878 may be used by service functions, or conveyed to another network 879 node post service path egress. 881 External (to the network) systems: External systems, such as 882 orchestration systems, often contain information that is valuable 883 for service function policy decisions. In most cases, this 884 information cannot be deduced by network nodes. For example, a 885 cloud orchestration platform placing workloads "knows" what 886 application is being instantiated and can communicate this 887 information to all NSH nodes via metadata carried in the context 888 header(s). 890 Service Functions: A classifier co-resident with Service Functions 891 often perform very detailed and valuable classification. In some 892 cases they may terminate, and be able to inspect encrypted 893 traffic. 895 Regardless of the source, metadata reflects the "result" of 896 classification. The granularity of classification may vary. For 897 example, a network switch, acting as a classifier, might only be able 898 to classify based on a 5-tuple, whereas, a service function may be 899 able to inspect application information. Regardless of granularity, 900 the classification information can be represented in NSH. 902 Once the data is added to NSH, it is carried along the service path, 903 NSH-aware SFs receive the metadata, and can use that metadata for 904 local decisions and policy enforcement. Figure 8 and Figure 9 905 highlight the relationship between metadata and policy: 907 +-------+ +-------+ +-------+ 908 | SFF )------->( SFF |------->| SFF | 909 +---^---+ +---|---+ +---|---+ 910 ,-|-. ,-|-. ,-|-. 911 / \ / \ / \ 912 ( Class ) ( SF1 ) ( SF2 ) 913 \ ify / \ / \ / 914 `---' `---' `---' 915 5-tuple: Permit Inspect 916 Tenant A Tenant A AppY 917 AppY 919 Figure 8: Metadata and Policy 921 +-----+ +-----+ +-----+ 922 | SFF |---------> | SFF |----------> | SFF | 923 +--+--+ +--+--+ +--+--+ 924 ^ | | 925 ,-+-. ,-+-. ,-+-. 926 / \ / \ / \ 927 ( Class ) ( SF1 ) ( SF2 ) 928 \ ify / \ / \ / 929 `-+-' `---' `---' 930 | Permit Deny AppZ 931 +---+---+ employees 932 | | 933 +-------+ 934 external 935 system: 936 Employee 937 AppZ 939 Figure 9: External Metadata and Policy 941 In both of the examples above, the service functions perform policy 942 decisions based on the result of the initial classification: the SFs 943 did not need to perform re-classification, rather they rely on a 944 antecedent classification for local policy enforcement. 946 Depending on the information carried in the metadata, data privacy 947 considerations may need to be considered. For example, if the 948 metadata conveys tenant information, that information may need to be 949 authenticated and/or encrypted between the originator and the 950 intended recipients (which may include intended SFs only) . NSH 951 itself does not provide privacy functions, rather it relies on the 952 transport/overlay layer. An operator can select the appropriate 953 transport to ensure the confidentially (and other security) 954 considerations are met. Metadata privacy and security considerations 955 are a matter for the documents that define metadata format. 957 7.2. Updating/Augmenting Metadata 959 Post-initial metadata imposition (typically performed during initial 960 service path determination), metadata may be augmented or updated: 962 1. Metadata Augmentation: Information may be added to NSH's existing 963 metadata, as depicted in Figure 10. For example, if the initial 964 classification returns the tenant information, a secondary 965 classification (perhaps co-resident with DPI or SLB) may augment 966 the tenant classification with application information, and 967 impose that new information in NSH metadata. The tenant 968 classification is still valid and present, but additional 969 information has been added to it. 971 2. Metadata Update: Subsequent classifiers may update the initial 972 classification if it is determined to be incorrect or not 973 descriptive enough. For example, the initial classifier adds 974 metadata that describes the traffic as "internet" but a security 975 service function determines that the traffic is really "attack". 976 Figure 11 illustrates an example of updating metadata. 978 +-----+ +-----+ +-----+ 979 | SFF |---------> | SFF |----------> | SFF | 980 +--+--+ +--+--+ +--+--+ 981 ^ | | 982 ,---. ,---. ,---. 983 / \ / \ / \ 984 ( Class ) ( SF1 ) ( SF2 ) 985 \ / \ / \ / 986 `-+-' `---' `---' 987 | Inspect Deny 988 +---+---+ employees employee+ 989 | | Class=AppZ appZ 990 +-------+ 991 external 992 system: 993 Employee 995 Figure 10: Metadata Augmentation 997 +-----+ +-----+ +-----+ 998 | SFF |---------> | SFF |----------> | SFF | 999 +--+--+ +--+--+ +--+--+ 1000 ^ | | 1001 ,---. ,---. ,---. 1002 / \ / \ / \ 1003 ( Class ) ( SF1 ) ( SF2 ) 1004 \ / \ / \ / 1005 `---' `---' `---' 1006 5-tuple: Inspect Deny 1007 Tenant A Tenant A attack 1008 --> attack 1010 Figure 11: Metadata Update 1012 7.3. Service Path Identifier and Metadata 1014 Metadata information may influence the service path selection since 1015 the Service Path Identifier values can represent the result of 1016 classification. A given SPI can be defined based on classification 1017 results (including metadata classification). The imposition of the 1018 SPI and SI results in the packet being placed on the newly specified 1019 SFP at the position indicated by the imposed SPI and SI. 1021 This relationship provides the ability to create a dynamic service 1022 plane based on complex classification without requiring each node to 1023 be capable of such classification, or requiring a coupling to the 1024 network topology. This yields service graph functionality as 1025 described in Section 7.4. Figure 12 illustrates an example of this 1026 behavior. 1028 +-----+ +-----+ +-----+ 1029 | SFF |---------> | SFF |------+---> | SFF | 1030 +--+--+ +--+--+ | +--+--+ 1031 | | | | 1032 ,---. ,---. | ,---. 1033 / \ / SF1 \ | / \ 1034 ( SCL ) ( + ) | ( SF2 ) 1035 \ / \SCL2 / | \ / 1036 `---' `---' +-----+ `---' 1037 5-tuple: Inspect | SFF | Original 1038 Tenant A Tenant A +--+--+ next SF 1039 --> DoS | 1040 V 1041 ,-+-. 1042 / \ 1043 ( SF10 ) 1044 \ / 1045 `---' 1046 DoS 1047 "Scrubber" 1049 Figure 12: Path ID and Metadata 1051 Specific algorithms for mapping metadata to an SPI are outside the 1052 scope of this document. 1054 8. Security Considerations 1056 As with many other protocols, NSH data can be spoofed or otherwise 1057 modified. In many deployments, NSH will be used in a controlled 1058 environment, with trusted devices (e.g., a data center) thus 1059 mitigating the risk of unauthorized header manipulation. 1061 NSH is always encapsulated in a transport protocol and therefore, 1062 when required, existing security protocols that provide authenticity 1063 (e.g., [RFC6071]) can be used. Similarly, if confidentiality is 1064 required, existing encryption protocols can be used in conjunction 1065 with encapsulated NSH. 1067 Further, existing best practices, such as [BCP38] should be deployed 1068 at the network layer to ensure that traffic entering the service path 1069 is indeed "valid". [I-D.ietf-rtgwg-dt-encap] provides additional 1070 transport encapsulation considerations. 1072 NSH metadata authenticity and confidentially must be considered as 1073 well. In order to protect the metadata, an operator can leverage the 1074 aforementioned mechanisms provided the transport layer, authenticity 1075 and/or confidentiality. An operator MUST carefully select the 1076 transport/underlay services to ensure end to end security services, 1077 when those are sought after. For example, if [RFC6071] is used, the 1078 operator MUST ensure it can be supported by the transport/underlay of 1079 all relevant network segments as well as SFF and SFs. Further, as 1080 described in Section 8.1, operators can and should use indirect 1081 identification for personally identifying information, thus 1082 significantly mitigating the risk of privacy violation. Means to 1083 prevent leaking privacy-related information outside an administrative 1084 domain are natively supported by NSH given that the last SFF of a 1085 path will systematically remove the NSH header before forwarding a 1086 packet upstream. 1088 Lastly, SF security, although out of scope of this document, should 1089 be considered, particularly if an SF needs to access, authenticate or 1090 update NSH metadata. 1092 9. Contributors 1094 This WG document originated as draft-quinn-sfc-nsh and had the 1095 following co-authors and contributors. The editors of this document 1096 would like to thank and recognize them and their contributions. 1097 These co-authors and contributors provided invaluable concepts and 1098 content for this document's creation. 1100 Surendra Kumar 1101 Cisco Systems 1102 smkumar@cisco.com 1104 Michael Smith 1105 Cisco Systems 1106 michsmit@cisco.com 1108 Jim Guichard 1109 Huawei 1110 james.n.guichard@huawei.com 1112 Rex Fernando 1113 Cisco Systems 1114 Email: rex@cisco.com 1116 Navindra Yadav 1117 Cisco Systems 1118 Email: nyadav@cisco.com 1120 Wim Henderickx 1121 Alcatel-Lucent 1122 wim.henderickx@alcatel-lucent.com 1124 Andrew Dolganow 1125 Alcaltel-Lucent 1126 Email: andrew.dolganow@alcatel-lucent.com 1128 Praveen Muley 1129 Alcaltel-Lucent 1130 Email: praveen.muley@alcatel-lucent.com 1132 Tom Nadeau 1133 Brocade 1134 tnadeau@lucidvision.com 1136 Puneet Agarwal 1137 puneet@acm.org 1139 Rajeev Manur 1140 Broadcom 1141 rmanur@broadcom.com 1143 Abhishek Chauhan 1144 Citrix 1145 Abhishek.Chauhan@citrix.com 1147 Joel Halpern 1148 Ericsson 1149 joel.halpern@ericsson.com 1151 Sumandra Majee 1152 F5 1153 S.Majee@f5.com 1155 David Melman 1156 Marvell 1157 davidme@marvell.com 1159 Pankaj Garg 1160 Microsoft 1161 pankajg@microsoft.com 1163 Brad McConnell 1164 Rackspace 1165 bmcconne@rackspace.com 1167 Chris Wright 1168 Red Hat Inc. 1169 chrisw@redhat.com 1171 Kevin Glavin 1172 Riverbed 1173 kevin.glavin@riverbed.com 1175 Hong (Cathy) Zhang 1176 Huawei US R&D 1177 cathy.h.zhang@huawei.com 1179 Louis Fourie 1180 Huawei US R&D 1181 louis.fourie@huawei.com 1183 Ron Parker 1184 Affirmed Networks 1185 ron_parker@affirmednetworks.com 1187 Myo Zarny 1188 Goldman Sachs 1189 myo.zarny@gs.com 1191 10. Acknowledgments 1193 The authors would like to thank Sunil Vallamkonda, Nagaraj Bagepalli, 1194 Abhijit Patra, Peter Bosch, Darrel Lewis, Pritesh Kothari, Tal 1195 Mizrahi and Ken Gray for their detailed review, comments and 1196 contributions. 1198 A special thank you goes to David Ward and Tom Edsall for their 1199 guidance and feedback. 1201 Additionally the authors would like to thank Larry Kreeger for his 1202 invaluable ideas and contributions which are reflected throughout 1203 this document. 1205 Loa Andersson provided a thorough review and valuable comments, we 1206 thank him for that. 1208 Reinaldo Penno deserves a particular thank you for his architecture 1209 and implementation work that helped guide the protocol concepts and 1210 design. 1212 The editors also acknowledge a comprehensive review and respective 1213 suggestions by Med Boucadair. 1215 Lastly, David Dolson has provides significant review, feedback and 1216 suggestions throughout the evolution of this document. His 1217 contributions are very much appreciated. 1219 11. IANA Considerations 1221 11.1. NSH EtherType 1223 An IEEE EtherType, 0x894F, has been allocated for NSH. 1225 11.2. Network Service Header (NSH) Parameters 1227 IANA is requested to create a new "Network Service Header (NSH) 1228 Parameters" registry. The following sub-sections request new 1229 registries within the "Network Service Header (NSH) Parameters " 1230 registry. 1232 11.2.1. NSH Base Header Unassigned Bits 1234 There are five unassigned bits in the NSH Base Header. New bits are 1235 assigned via Standards Action [RFC8126]. 1236 Bit 3 - Unassigned 1237 Bits 16-19 - Unassigned 1239 11.2.2. NSH Version 1241 IANA is requested to setup a registry of "NSH Version". New values 1242 are assigned via Standards Action [RFC8126]. 1244 Version 00b: This protocol version. This document. 1245 Version 01b: Reserved. This document. 1246 Version 10b: Unassigned. 1247 Version 11b: Unassigned. 1249 11.2.3. MD Type Registry 1251 IANA is requested to set up a registry of "MD Types". These are 1252 4-bit values. MD Type values 0x0, 0x1, 0x2, and 0xF are specified in 1253 this document, see Table 5. Registry entries are assigned by using 1254 the "IETF Review" policy defined in RFC 8126 [RFC8126]. 1256 +----------+-----------------+---------------+ 1257 | MD Type | Description | Reference | 1258 +----------+-----------------+---------------+ 1259 | 0x0 | Reserved | This document | 1260 | | | | 1261 | 0x1 | NSH MD Type 1 | This document | 1262 | | | | 1263 | 0x2 | NSH MD Type 2 | This document | 1264 | | | | 1265 | 0x3..0xE | Unassigned | | 1266 | | | | 1267 | 0xF | Experimentation | This document | 1268 +----------+-----------------+---------------+ 1270 Table 5: MD Type Values 1272 11.2.4. MD Class Registry 1274 IANA is requested to set up a registry of "MD Class". These are 16- 1275 bit values. New allocations are to be made according to the 1276 following policies: 1278 0x0000 to 0x01ff: IETF Review 1279 0x0200 to 0xfff5: Expert Review 1280 0xfff6 to 0xfffe: Experimental 1281 0xffff: Reserved 1283 IANA is requested to assign the values as per Table 6:: 1285 +-----------+-----------------------------+------------+ 1286 | MD Class | Meaning | Reference | 1287 +-----------+-----------------------------+------------+ 1288 | 0x0000 | IETF Base NSH MD Class | This.I-D | 1289 +-----------+-----------------------------+------------+ 1291 Table 6: MD Class Value 1293 Designated Experts evaluating new allocation requests from the 1294 "Expert Review" range should principally consider whether a new MD 1295 class is needed compared to adding MD types to an existing class. 1296 The Designated Experts should also encourage the existence of an 1297 associated and publicly visible registry of MD types although this 1298 registry need not be maintained by IANA. 1300 11.2.5. NSH Base Header Next Protocol 1302 IANA is requested to set up a registry of "Next Protocol". These are 1303 8-bit values. Next Protocol values 0, 1, 2, 3, 4 and 5 are defined 1304 in this document (see Table 7. New values are assigned via "Expert 1305 Reviews" as per [RFC8126]. 1307 +---------------+--------------+---------------+ 1308 | Next Protocol | Description | Reference | 1309 +---------------+--------------+---------------+ 1310 | 0x0 | Unassigned | | 1311 | | | | 1312 | 0x1 | IPv4 | This document | 1313 | | | | 1314 | 0x2 | IPv6 | This document | 1315 | | | | 1316 | 0x3 | Ethernet | This document | 1317 | | | | 1318 | 0x4 | NSH | This document | 1319 | | | | 1320 | 0x5 | MPLS | This document | 1321 | | | | 1322 | 0x6..0xFD | Unassigned | | 1323 | | | | 1324 | 0xFE | Experiment 1 | This document | 1325 | | | | 1326 | 0xFF | Experiment 2 | This document | 1327 +---------------+--------------+---------------+ 1329 Table 7: NSH Base Header Next Protocol Values 1331 11.2.6. New IETF assigned MD Type Registry 1333 This document requests IANA to create a registry for the type values 1334 owned by the IETF (i.e., MD Class set to 0x0000) called the "IETF 1335 Assigned MD Type Registry." 1337 The type values are assigned via Standards Action [RFC8126]. 1339 No initial values are assigned at the creation of the registry. 1341 12. References 1343 12.1. Normative References 1345 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1346 Requirement Levels", BCP 14, RFC 2119, 1347 DOI 10.17487/RFC2119, March 1997, 1348 . 1350 [RFC7665] Halpern, J., Ed. and C. Pignataro, Ed., "Service Function 1351 Chaining (SFC) Architecture", RFC 7665, 1352 DOI 10.17487/RFC7665, October 2015, 1353 . 1355 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 1356 Writing an IANA Considerations Section in RFCs", BCP 26, 1357 RFC 8126, DOI 10.17487/RFC8126, June 2017, 1358 . 1360 12.2. Informative References 1362 [BCP38] Ferguson, P. and D. Senie, "Network Ingress Filtering: 1363 Defeating Denial of Service Attacks which employ IP Source 1364 Address Spoofing", BCP 38, RFC 2827, DOI 10.17487/RFC2827, 1365 May 2000, . 1367 [I-D.guichard-sfc-nsh-dc-allocation] 1368 Guichard, J., Smith, M., Surendra, S., Majee, S., Agarwal, 1369 P., Glavin, K., and Y. Laribi, "Network Service Header 1370 (NSH) Context Header Allocation (Data Center)", draft- 1371 guichard-sfc-nsh-dc-allocation-05 (work in progress), 1372 August 2016. 1374 [I-D.ietf-nvo3-vxlan-gpe] 1375 Maino, F., Kreeger, L., and U. Elzur, "Generic Protocol 1376 Extension for VXLAN", draft-ietf-nvo3-vxlan-gpe-04 (work 1377 in progress), April 2017. 1379 [I-D.ietf-rtgwg-dt-encap] 1380 Nordmark, E., Tian, A., Gross, J., Hudson, J., Kreeger, 1381 L., Garg, P., Thaler, P., and T. Herbert, "Encapsulation 1382 Considerations", draft-ietf-rtgwg-dt-encap-02 (work in 1383 progress), October 2016. 1385 [I-D.ietf-sfc-control-plane] 1386 Boucadair, M., "Service Function Chaining (SFC) Control 1387 Plane Components & Requirements", draft-ietf-sfc-control- 1388 plane-08 (work in progress), October 2016. 1390 [I-D.ietf-sfc-oam-framework] 1391 Aldrin, S., Pignataro, C., Kumar, N., Akiya, N., Krishnan, 1392 R., and A. Ghanwani, "Service Function Chaining Operation, 1393 Administration and Maintenance Framework", draft-ietf-sfc- 1394 oam-framework-02 (work in progress), July 2017. 1396 [I-D.napper-sfc-nsh-broadband-allocation] 1397 Napper, J., Kumar, S., Muley, P., Henderickx, W., and M. 1398 Boucadair, "NSH Context Header Allocation -- Broadband", 1399 draft-napper-sfc-nsh-broadband-allocation-02 (work in 1400 progress), January 2017. 1402 [RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P. 1403 Traina, "Generic Routing Encapsulation (GRE)", RFC 2784, 1404 DOI 10.17487/RFC2784, March 2000, 1405 . 1407 [RFC3692] Narten, T., "Assigning Experimental and Testing Numbers 1408 Considered Useful", BCP 82, RFC 3692, 1409 DOI 10.17487/RFC3692, January 2004, 1410 . 1412 [RFC6071] Frankel, S. and S. Krishnan, "IP Security (IPsec) and 1413 Internet Key Exchange (IKE) Document Roadmap", RFC 6071, 1414 DOI 10.17487/RFC6071, February 2011, 1415 . 1417 [RFC7325] Villamizar, C., Ed., Kompella, K., Amante, S., Malis, A., 1418 and C. Pignataro, "MPLS Forwarding Compliance and 1419 Performance Requirements", RFC 7325, DOI 10.17487/RFC7325, 1420 August 2014, . 1422 [RFC7498] Quinn, P., Ed. and T. Nadeau, Ed., "Problem Statement for 1423 Service Function Chaining", RFC 7498, 1424 DOI 10.17487/RFC7498, April 2015, 1425 . 1427 Authors' Addresses 1429 Paul Quinn (editor) 1430 Cisco Systems, Inc. 1432 Email: paulq@cisco.com 1433 Uri Elzur (editor) 1434 Intel 1436 Email: uri.elzur@intel.com 1438 Carlos Pignataro (editor) 1439 Cisco Systems, Inc. 1441 Email: cpignata@cisco.com