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2 Network Working Group P. Quinn
3 Internet-Draft J. Guichard
4 Intended status: Standards Track S. Kumar
5 Expires: August 28, 2015 M. Smith
6 Cisco Systems, Inc.
7 W. Henderickx
8 Alcatel-Lucent
9 T. Nadeau
10 Brocade
11 P. Agarwal
13 R. Manur
14 Broadcom
15 A. Chauhan
16 Citrix
17 J. Halpern
18 Ericsson
19 S. Majee
20 F5
21 U. Elzur
22 Intel
23 D. Melman
24 Marvell
25 P. Garg
26 Microsoft
27 B. McConnell
28 Rackspace
29 C. Wright
30 Red Hat Inc.
31 K. Glavin
32 Riverbed
33 C. Zhang
34 L. Fourie
35 Huawei US R&D
36 R. Parker
37 Affirmed Networks
38 M. Zarny
39 Goldman Sachs
40 February 24, 2015
42 Network Service Header
43 draft-quinn-sfc-nsh-07.txt
45 Abstract
47 This draft describes a Network Service Header (NSH) inserted onto
48 encapsulated packets or frames to realize service function paths.
50 NSH also provides a mechanism for metadata exchange along the
51 instantiated service path.
53 1. Requirements Language
55 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
56 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
57 document are to be interpreted as described in RFC 2119 [RFC2119].
59 Status of this Memo
61 This Internet-Draft is submitted in full conformance with the
62 provisions of BCP 78 and BCP 79.
64 Internet-Drafts are working documents of the Internet Engineering
65 Task Force (IETF). Note that other groups may also distribute
66 working documents as Internet-Drafts. The list of current Internet-
67 Drafts is at http://datatracker.ietf.org/drafts/current/.
69 Internet-Drafts are draft documents valid for a maximum of six months
70 and may be updated, replaced, or obsoleted by other documents at any
71 time. It is inappropriate to use Internet-Drafts as reference
72 material or to cite them other than as "work in progress."
74 This Internet-Draft will expire on August 28, 2015.
76 Copyright Notice
78 Copyright (c) 2015 IETF Trust and the persons identified as the
79 document authors. All rights reserved.
81 This document is subject to BCP 78 and the IETF Trust's Legal
82 Provisions Relating to IETF Documents
83 (http://trustee.ietf.org/license-info) in effect on the date of
84 publication of this document. Please review these documents
85 carefully, as they describe your rights and restrictions with respect
86 to this document. Code Components extracted from this document must
87 include Simplified BSD License text as described in Section 4.e of
88 the Trust Legal Provisions and are provided without warranty as
89 described in the Simplified BSD License.
91 Table of Contents
93 1. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
94 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5
95 2.1. Definition of Terms . . . . . . . . . . . . . . . . . . . 5
96 2.2. Problem Space . . . . . . . . . . . . . . . . . . . . . . 7
97 3. Network Service Header . . . . . . . . . . . . . . . . . . . . 9
98 3.1. Network Service Header Format . . . . . . . . . . . . . . 9
99 3.2. NSH Base Header . . . . . . . . . . . . . . . . . . . . . 9
100 3.3. Service Path Header . . . . . . . . . . . . . . . . . . . 11
101 3.4. NSH MD-type 1 . . . . . . . . . . . . . . . . . . . . . . 11
102 3.4.1. Mandatory Context Header Allocation Guidelines . . . . 12
103 3.5. NSH MD-type 2 . . . . . . . . . . . . . . . . . . . . . . 13
104 3.5.1. Optional Variable Length Metadata . . . . . . . . . . 14
105 4. NSH Actions . . . . . . . . . . . . . . . . . . . . . . . . . 16
106 5. NSH Encapsulation . . . . . . . . . . . . . . . . . . . . . . 18
107 6. NSH Usage . . . . . . . . . . . . . . . . . . . . . . . . . . 19
108 7. NSH Proxy Nodes . . . . . . . . . . . . . . . . . . . . . . . 20
109 8. Fragmentation Considerations . . . . . . . . . . . . . . . . . 21
110 9. Service Path Forwarding with NSH . . . . . . . . . . . . . . . 22
111 9.1. SFFs and Overlay Selection . . . . . . . . . . . . . . . . 22
112 9.2. Mapping NSH to Network Overlay . . . . . . . . . . . . . . 24
113 9.3. Service Plane Visibility . . . . . . . . . . . . . . . . . 25
114 9.4. Service Graphs . . . . . . . . . . . . . . . . . . . . . . 25
115 10. Policy Enforcement with NSH . . . . . . . . . . . . . . . . . 27
116 10.1. NSH Metadata and Policy Enforcement . . . . . . . . . . . 27
117 10.2. Updating/Augmenting Metadata . . . . . . . . . . . . . . . 28
118 10.3. Service Path ID and Metadata . . . . . . . . . . . . . . . 30
119 11. NSH Encapsulation Examples . . . . . . . . . . . . . . . . . . 31
120 11.1. GRE + NSH . . . . . . . . . . . . . . . . . . . . . . . . 31
121 11.2. VXLAN-gpe + NSH . . . . . . . . . . . . . . . . . . . . . 31
122 11.3. Ethernet + NSH . . . . . . . . . . . . . . . . . . . . . . 32
123 12. Security Considerations . . . . . . . . . . . . . . . . . . . 33
124 13. Open Items for WG Discussion . . . . . . . . . . . . . . . . . 34
125 14. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 35
126 15. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 36
127 16. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 37
128 16.1. NSH EtherType . . . . . . . . . . . . . . . . . . . . . . 37
129 16.2. Network Service Header (NSH) Parameters . . . . . . . . . 37
130 16.2.1. NSH Base Header Reserved Bits . . . . . . . . . . . . 37
131 16.2.2. MD Type Registry . . . . . . . . . . . . . . . . . . . 37
132 16.2.3. TLV Class Registry . . . . . . . . . . . . . . . . . . 38
133 16.2.4. NSH Base Header Next Protocol . . . . . . . . . . . . 38
134 17. References . . . . . . . . . . . . . . . . . . . . . . . . . . 39
135 17.1. Normative References . . . . . . . . . . . . . . . . . . . 39
136 17.2. Informative References . . . . . . . . . . . . . . . . . . 39
137 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 41
139 2. Introduction
141 Service functions are widely deployed and essential in many networks.
142 These service functions provide a range of features such as security,
143 WAN acceleration, and server load balancing. Service functions may
144 be instantiated at different points in the network infrastructure
145 such as the wide area network, data center, campus, and so forth.
147 The current service function deployment models are relatively static,
148 and bound to topology for insertion and policy selection.
149 Furthermore, they do not adapt well to elastic service environments
150 enabled by virtualization.
152 New data center network and cloud architectures require more flexible
153 service function deployment models. Additionally, the transition to
154 virtual platforms requires an agile service insertion model that
155 supports elastic service delivery; the movement of service functions
156 and application workloads in the network and the ability to easily
157 bind service policy to granular information such as per-subscriber
158 state are necessary.
160 The approach taken by NSH is composed of the following elements:
162 1. Service path identification
164 2. Transport independent per-packet/frame service metadata.
166 3. Optional variable TLV metadata.
168 NSH is designed to be easy to implement across a range of devices,
169 both physical and virtual, including hardware platforms.
171 An NSH aware control plane is outside the scope of this document.
173 The SFC Architecture document [SFC-arch] provides an overview of a
174 service chaining architecture that clearly defines the roles of the
175 various elements and the scope of a service function chaining
176 encapsulation.
178 2.1. Definition of Terms
180 Classification: Locally instantiated policy and customer/network/
181 service profile matching of traffic flows for identification of
182 appropriate outbound forwarding actions.
184 SFC Network Forwarder (NF): SFC network forwarders provide network
185 connectivity for service functions forwarders and service
186 functions. SFC network forwarders participate in the network
187 overlay used for service function chaining as well as in the SFC
188 encapsulation.
190 Service Function Forwarder (SFF): A service function forwarder is
191 responsible for delivering traffic received from the NF to one or
192 more connected service functions, and from service functions to
193 the NF.
195 Service Function (SF): A function that is responsible for specific
196 treatment of received packets. A service function can act at the
197 network layer or other OSI layers. A service function can be a
198 virtual instance or be embedded in a physical network element.
199 One of multiple service functions can be embedded in the same
200 network element. Multiple instances of the service function can
201 be enabled in the same administrative domain.
203 Service Node (SN): Physical or virtual element that hosts one or
204 more service functions and has one or more network locators
205 associated with it for reachability and service delivery.
207 Service Function Chain (SFC): A service function chain defines an
208 ordered set of service functions that must be applied to packets
209 and/or frames selected as a result of classification. The implied
210 order may not be a linear progression as the architecture allows
211 for nodes that copy to more than one branch. The term service
212 chain is often used as shorthand for service function chain.
214 Service Function Path (SFP): The instantiation of a SFC in the
215 network. Packets follow a service function path from a classifier
216 through the requisite service functions
218 Network Node/Element: Device that forwards packets or frames based
219 on outer header information. In most cases is not aware of the
220 presence of NSH.
222 Network Overlay: Logical network built on top of existing network
223 (the underlay). Packets are encapsulated or tunneled to create
224 the overlay network topology.
226 Network Service Header: Data plane header added to frames/packets.
227 The header contains information required for service chaining, as
228 well as metadata added and consumed by network nodes and service
229 elements.
231 Service Classifier: Function that performs classification and
232 imposes an NSH. Creates a service path. Non-initial (i.e.
233 subsequent) classification can occur as needed and can alter, or
234 create a new service path.
236 Service Hop: NSH aware node, akin to an IP hop but in the service
237 overlay.
239 Service Path Segment: A segment of a service path overlay.
241 NSH Proxy: Acts as a gateway: removes and inserts NSH on behalf of a
242 service function that is not NSH aware.
244 2.2. Problem Space
246 Network Service Header (NSH) addresses several limitations associated
247 with service function deployments today.
249 1. Topological Dependencies: Network service deployments are often
250 coupled to network topology. Such dependency imposes constraints
251 on the service delivery, potentially inhibiting the network
252 operator from optimally utilizing service resources, and reduces
253 the flexibility. This limits scale, capacity, and redundancy
254 across network resources.
256 2. Service Chain Construction: Service function chains today are
257 most typically built through manual configuration processes.
258 These are slow and error prone. With the advent of newer service
259 deployment models the control/management planes provide not only
260 connectivity state, but will also be increasingly utilized for
261 the creation of network services. Such a control/management
262 planes could be centralized, or be distributed.
264 3. Application of Service Policy: Service functions rely on topology
265 information such as VLANs or packet (re) classification to
266 determine service policy selection, i.e. the service function
267 specific action taken. Topology information is increasingly less
268 viable due to scaling, tenancy and complexity reasons. The
269 topological information is often stale, providing the operator
270 with inaccurate placement that can result in suboptimal resource
271 utilization. Furthermore topology-centric information often does
272 not convey adequate information to the service functions, forcing
273 functions to individually perform more granular classification.
275 4. Per-Service (re)Classification: Classification occurs at each
276 service function independent from previously applied service
277 functions. More importantly, the classification functionality
278 often differs per service function and service functions may not
279 leverage the results from other service functions.
281 5. Common Header Format: Various proprietary methods are used to
282 share metadata and create service paths. An open header provides
283 a common format for all network and service devices.
285 6. Limited End-to-End Service Visibility: Troubleshooting service
286 related issues is a complex process that involve both network-
287 specific and service-specific expertise. This is especially the
288 case when service function chains span multiple DCs, or across
289 administrative boundaries. Furthermore, the physical and virtual
290 environments (network and service) can be highly divergent in
291 terms of topology and that topological variance adds to these
292 challenges.
294 7. Transport Dependence: Service functions can and will be deployed
295 in networks with a range of transports requiring service
296 functions to support and participate in many transports (and
297 associated control planes) or for a transport gateway function to
298 be present.
300 Please see the Service Function Chaining Problem Statement [SFC-PS]
301 for a more detailed analysis of service function deployment problem
302 areas.
304 3. Network Service Header
306 A Network Service Header (NSH) contains metadata and service path
307 information that are added to a packet or frame and used to create a
308 service plane. The packets and the NSH are then encapsulated in an
309 outer header for transport.
311 The service header is added by a service classification function - a
312 device or application - that determines which packets require
313 servicing, and correspondingly which service path to follow to apply
314 the appropriate service.
316 3.1. Network Service Header Format
318 An NSH is composed of a 4-byte base header, a 4-byte service path
319 header and context headers, as shown in Figure 1 below.
321 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
322 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
323 | Base Header |
324 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
325 | Service Path Header |
326 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
327 | |
328 ~ Context Headers ~
329 | |
330 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
332 Figure 1: Network Service Header
334 Base header: provides information about the service header and the
335 payload protocol.
337 Service Path Header: provide path identification and location within
338 a path.
340 Context headers: carry opaque metadata and variable length encoded
341 information.
343 3.2. NSH Base Header
345 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
346 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
347 |Ver|O|C|R|R|R|R|R|R| Length | MD Type | Next Protocol |
348 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
349 Figure 2: NSH Base Header
351 Base Header Field Descriptions
353 Version: The version field is used to ensure backward compatibility
354 going forward with future NSH updates.
356 O bit: Indicates that this packet is an operations and management
357 (OAM) packet. SFF and SFs nodes MUST examine the payload and take
358 appropriate action (e.g. return status information).
360 OAM message specifics and handling details are outside the scope of
361 this document.
363 C bit: Indicates that a critical metadata TLV is present (see Section
364 3.4.2). This bit acts as an indication for hardware implementers to
365 decide how to handle the presence of a critical TLV without
366 necessarily needing to parse all TLVs present. The C bit MUST be set
367 to 1 if one or more critical TLVs are present.
369 All other flag fields are reserved.
371 Length: total length, in 4-byte words, of the NSH header, including
372 optional variable TLVs.
374 MD Type: indicates the format of NSH beyond the base header and the
375 type of metadata being carried. This typing is used to describe the
376 use for the metadata. A new registry will be requested from IANA for
377 the MD Type.
379 NSH defines two MD types:
381 0x1 which indicates that the format of the header includes fixed
382 length context headers.
384 0x2 which does not mandate any headers beyond the base header and
385 service path header, and may contain optional variable length context
386 information.
388 The format of the base header is invariant, and not described by MD
389 Type.
391 NSH implementations MUST support MD-Type 0x1, and SHOULD support MD-
392 Type 0x2.
394 Next Protocol: indicates the protocol type of the original packet. A
395 new IANA registry will be created for protocol type.
397 This draft defines the following Next Protocol values:
399 0x1 : IPv4
400 0x2 : IPv6
401 0x3 : Ethernet
403 3.3. Service Path Header
405 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
406 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
407 | Service Path ID | Service Index |
408 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
410 Service path ID (SPI): 24 bits
411 Service index (SI): 8 bits
413 Figure 3: NSH Service Path Header
415 Service Path Identifier (SPI): identifies a service path.
416 Participating nodes MUST use this identifier for path selection. An
417 administrator can use the service path value for reporting and
418 troubleshooting packets along a specific path.
420 Service Index (SI): provides location within the service path.
421 Service index MUST be decremented by service functions or proxy nodes
422 after performing required services. MAY be used in conjunction with
423 service path for path selection. Service Index is also valuable when
424 troubleshooting/reporting service paths. In addition to location
425 within a path, SI can be used for loop detection.
427 3.4. NSH MD-type 1
429 When the base header specifies MD Type 1, NSH defines four 4-byte
430 mandatory context headers, as per Figure 4. These headers must be
431 present and the format is opaque as depicted in Figure 5.
433 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
434 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
435 |Ver|O|C|R|R|R|R|R|R| Length | MD-type=0x1 | Next Protocol |
436 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
437 | Service Path ID | Service Index |
438 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
439 | Mandatory Context Header |
440 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
441 | Mandatory Context Header |
442 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
443 | Mandatory Context Header |
444 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
445 | Mandatory Context Header |
446 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
448 Figure 4: NSH MD-type=0x1
450 0 1 2 3
451 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
452 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
453 | Context data |
454 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
456 Figure 5: Context Header
458 3.4.1. Mandatory Context Header Allocation Guidelines
460 0 1 2 3
461 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
462 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
463 | Network Platform Context |
464 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
465 | Network Shared Context |
466 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
467 | Service Platform Context |
468 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
469 | Service Shared Context |
470 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
471 Figure 6: Context Data Significance
473 Figure 6, above, and the following examples of context header
474 allocation are guidelines that illustrate how various forms of
475 information can be carried and exchanged via NSH.
477 Network platform context: provides platform-specific metadata shared
478 between network nodes. Examples include (but are not limited to)
479 ingress port information, forwarding context and encapsulation type.
481 Network shared context: metadata relevant to any network node such as
482 the result of edge classification. For example, application
483 information, identity information or tenancy information can be
484 shared using this context header.
486 Service platform context: provides service platform specific metadata
487 shared between service functions. This context header is analogous
488 to the network platform context, enabling service platforms to
489 exchange platform-centric information such as an identifier used for
490 load balancing decisions.
492 Service shared context: metadata relevant to, and shared, between
493 service functions. As with the shared network context,
494 classification information such as application type can be conveyed
495 using this context.
497 The data center[dcalloc] and mobility[moballoc] context header
498 allocation drafts provide guidelines for the semantics of NSH fixed
499 context headers in each respective environment.
501 3.5. NSH MD-type 2
503 When the base header specifies MD Type 2, NSH defines variable length
504 only context headers. There may be zero or more of these headers as
505 per the length field.
507 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
508 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
509 |Ver|O|C|R|R|R|R|R|R| Length | MD-type=0x2 | Next Protocol |
510 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
511 | Service Path ID | Service Index |
512 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
513 | |
514 ~ Optional Variable Length Context Headers ~
515 | |
516 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
517 Figure 7: NSH MD-type=0x2
519 3.5.1. Optional Variable Length Metadata
521 NSH MD Type 2 MAY contain optional variable length context headers.
522 The format of these headers is as described below.
524 0 1 2 3
525 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
526 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
527 | TLV Class | Type |R|R|R| Len |
528 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
529 | Variable Metadata |
530 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
532 Figure 8: Variable Context Headers
534 TLV Class: describes the scope of the "Type" field. In some cases,
535 the TLV Class will identify a specific vendor, in others, the TLV
536 Class will identify specific standards body allocated types.
538 Type: the specific type of information being carried, within the
539 scope of a given TLV Class. Value allocation is the responsibility
540 of the TLV Class owner.
542 The most significant bit of the Type field indicates whether the TLV
543 is mandatory for the receiver to understand/process. This
544 effectively allocates Type values 0 to 127 for non-critical options
545 and Type values 128 to 255 for critical options. Figure 7 below
546 illustrates the placement of the Critical bit within the Type field.
548 +-+-+-+-+-+-+-+-+
549 |C| Type |
550 +-+-+-+-+-+-+-+-+
552 Figure 9: Critical Bit Placement Within the TLV Type Field
554 Encoding the criticality of the TLV within the Type field is
555 consistent with IPv6 option types.
557 If a receiver receives an encapsulated packet containing a TLV with
558 the Critical bit set in the Type field and it does not understand how
559 to process the Type, it MUST drop the packet. Transit devices MUST
560 NOT drop packets based on the setting of this bit.
562 Reserved bits: three reserved bit are present for future use. The
563 reserved bits MUST be zero.
565 Length: Length of the variable metadata, in 4-byte words.
567 4. NSH Actions
569 Service header aware nodes - service classifiers, SFF, SF and NSH
570 proxies, have several possible header related actions:
572 1. Insert or remove service header: These actions can occur at the
573 start and end respectively of a service path. Packets are
574 classified, and if determined to require servicing, a service
575 header imposed. The last node in a service path, an SFF, removes
576 the NSH. A service classifier MUST insert an NSH. At the end of
577 a service function chain, the last node operating on the service
578 header MUST remove it.
580 A service function can re-classify data as required and that re-
581 classification might result in a new service path. In this case,
582 the SF acts as a logical classifier as well. When the logical
583 classifier performs re-classification that results in a change of
584 service path, it MUST remove the existing NSH and MUST impose a
585 new NSH with the base header reflecting the new path.
587 2. Select service path: The base header provides service chain
588 information and is used by SFFs to determine correct service path
589 selection. SFFs MUST use the base header for selecting the next
590 service in the service path.
592 3. Update a service header: NSH aware service functions MUST
593 decrement the service index. A service index = 0 indicates that
594 a packet MUST be dropped by the SFF performing NSH-based
595 forwarding.
597 Service functions MAY update context headers if new/updated
598 context is available.
600 If an NSH proxy (see Section 7) is in use (acting on behalf of a
601 non-NSH-aware service function for NSH actions), then the proxy
602 MUST update service index and MAY update contexts. When an NSH
603 proxy receives an NSH-encapsulated packet, it removes the NSH
604 before forwarding it to an NSH unaware SF. When it receives a
605 packet back from an NSH unaware SF, it re-encapsulates it with
606 the NSH, decrementing the service index.
608 4. Service policy selection: Service function instances derive
609 policy selection from the service header. Context shared in the
610 service header can provide a range of service-relevant
611 information such as traffic classification. Service functions
612 SHOULD use NSH to select local service policy.
614 Figure 10 maps each of the four actions above to the components in
615 the SFC architecture that can perform it.
617 +----------------+--------------------+-------+---------------+-------+
618 | | Insert or remove |Select | Update a |Service|
619 | | service header |service|service header |Policy |
620 | +------+------+------+ path +---------------+Select-|
621 | |Insert|Remove|Remove| | Dec. |Update |ion |
622 | | | | and | |Service|Context| |
623 | Component | | |Insert| | Index |Header | |
624 +----------------+------+------+------+-------+-------+-------+-------+
625 |Service Classif-| + | | | | | + | |
626 |ication Function| | | | | | | |
627 + -------------- + ---- + ---- + ---- + ----- + ----- + ----- + ----- +
628 |Service Function| | + | | + | | + | |
629 |Forwarder(SFF) | | | | | | | |
630 + -------------- + ---- + ---- + ---- + ----- + ----- + ----- + ----- +
631 |Service | | | | | + | + | + |
632 |Function (SF) | | | | | | | |
633 + -------------- + ---- + ---- + ---- + ----- + ----- + ----- + ----- +
634 |NSH Proxy | + | + | | | + | + | |
635 +----------------+------+------+------+-------+-------+-------+-------+
637 Figure 10: NSH Action and Role Mapping
639 5. NSH Encapsulation
641 Once NSH is added to a packet, an outer encapsulation is used to
642 forward the original packet and the associated metadata to the start
643 of a service chain. The encapsulation serves two purposes:
645 1. Creates a topologically independent services plane. Packets are
646 forwarded to the required services without changing the
647 underlying network topology.
649 2. Transit network nodes simply forward the encapsulated packets as
650 is.
652 The service header is independent of the encapsulation used and is
653 encapsulated in existing transports. The presence of NSH is
654 indicated via protocol type or other indicator in the outer
655 encapsulation.
657 See Section 11 for NSH encapsulation examples.
659 6. NSH Usage
661 The NSH creates a dedicated service plane, that addresses many of the
662 limitations highlighted in Section 2.2. More specifically, NSH
663 enables:
665 1. Topological Independence: Service forwarding occurs within the
666 service plane, via a network overlay, the underlying network
667 topology does not require modification. Service functions have
668 one or more network locators (e.g. IP address) to receive/send
669 data within the service plane, the NSH contains an identifier
670 that is used to uniquely identify a service path and the services
671 within that path.
673 2. Service Chaining: NSH contains path identification information
674 needed to realize a service path. Furthermore, NSH provides the
675 ability to monitor and troubleshoot a service chain, end-to-end
676 via service-specific OAM messages. The NSH fields can be used by
677 administrators (via, for example a traffic analyzer) to verify
678 (account, ensure correct chaining, provide reports, etc.) the
679 path specifics of packets being forwarded along a service path.
681 3. Metadata Sharing: NSH provides a mechanism to carry shared
682 metadata between network devices and service function, and
683 between service functions. The semantics of the shared metadata
684 is communicated via a control plane to participating nodes.
685 Examples of metadata include classification information used for
686 policy enforcement and network context for forwarding post
687 service delivery.
689 4. Transport Agnostic: NSH is transport independent and is carried
690 in an overlay, over existing underlays. If an existing overlay
691 topology provides the required service path connectivity, that
692 existing overlay may be used.
694 7. NSH Proxy Nodes
696 In order to support NSH-unaware service functions, an NSH proxy is
697 used. The proxy node removes the NSH header and delivers the
698 original packet/frame via a local attachment circuit to the service
699 function. Examples of a local attachment circuit include, but are
700 not limited to: VLANs, IP in IP, GRE, VXLAN. When complete, the
701 service function returns the packet to the NSH proxy via the same or
702 different attachment circuit.
704 NSH is re-imposed on packets returned to the proxy from the non-NSH-
705 aware service.
707 Typically, an SFF will act as an NSH-proxy when required.
709 An NSH proxy MUST perform NSH actions as described in Section 4.
711 8. Fragmentation Considerations
713 Work in progress
715 9. Service Path Forwarding with NSH
717 9.1. SFFs and Overlay Selection
719 As described above, NSH contains a service path identifier (SPI) and
720 a service index (SI). The SPI is, as per its name, an identifier.
721 The SPI alone cannot be used to forward packets along a service path.
722 Rather the SPI provide a level of indirection between the service
723 path/topology and the network transport. Furthermore, there is no
724 requirement, or expectation of an SPI being bound to a pre-determined
725 or static network path.
727 The service index provides an indication of location within a service
728 path. The combination of SPI and SI provides the identification and
729 location of a logical SF (locator and order). The logical SF may be
730 a single SF, or a set of SFs that are equivalent. In the latter
731 case, the SFF provides load distribution amongst the collection of
732 SFs as needed. SI may also serve as a mechanism for loop detection
733 with in a service path since each SF in the path decrements the
734 index; an index of 0 indicates that a loop occurred and packet must
735 be discarded.
737 This indirection -- path ID to overlay -- creates a true service
738 plane. That is the SFF/SF topology is constructed without impacting
739 the network topology but more importantly service plane only
740 participants (i.e. most SFs) need not be part of the network overlay
741 topology and its associated infrastructure (e.g. control plane,
742 routing tables, etc.). As mentioned above, an existing overlay
743 topology may be used provided it offers the requisite connectivity.
745 The mapping of SPI to transport occurs on an SFF. The SFF consults
746 the SPI/ID values to determine the appropriate overlay transport
747 protocol (several may be used within a given network) and next hop
748 for the requisite SF. Figure 10 below depicts an SPI/SI to network
749 overlay mapping.
751 +-------------------------------------------------------+
752 | SPI | SI | NH | Transport |
753 +-------------------------------------------------------+
754 | 10 | 3 | 1.1.1.1 | VXLAN-gpe |
755 | 10 | 2 | 2.2.2.2 | nvGRE |
756 | 245 | 12 | 192.168.45.3 | VXLAN-gpe |
757 | 10 | 9 | 10.1.2.3 | GRE |
758 | 40 | 9 | 10.1.2.3 | GRE |
759 | 50 | 7 | 01:23:45:67:89:ab | Ethernet |
760 | 15 | 1 | Null (end of path) | None |
761 +-------------------------------------------------------+
762 Figure 11: SFF NSH Mapping Example
764 Additionally, further indirection is possible: the resolution of the
765 required SF function locator may be a localized resolution on an
766 SFF,rather than a service function chain control plane
767 responsibility, as per figures 11 and 12 below.
769 +-------------------+
770 | SPI | SI | NH |
771 +-------------------+
772 | 10 | 3 | SF2 |
773 | 245 | 12 | SF34 |
774 | 40 | 9 | SF9 |
775 +-------------------+
777 Figure 12: NSH to SF Mapping Example
779 +-----------------------------------+
780 | SF | NH | Transport |
781 +-----------------------------------|
782 | SF2 | 10.1.1.1 | VXLAN-gpe |
783 | SF34| 192.168.1.1 | UDP |
784 | SF9 | 1.1.1.1 | GRE |
785 +-----------------------------------+
787 Figure 13: SF Locator Mapping Example
789 Since the SPI is a representation of the service path, the lookup may
790 return more than one possible next-hop within a service path for a
791 given SF, essentially a series of weighted (equally or otherwise)
792 overlay links to be used (for load distribution, redundancy or
793 policy), see Figure 13. The metric depicted in Figure 13 is an
794 example to help illustrated weighing SFs. In a real network, the
795 metric will range from a simple preference (similar to routing next-
796 hop), to a true dynamic composite metric based on some service
797 function-centric state (including load, sessions sate, capacity,
798 etc.)
799 +----------------------------------+
800 | SPI | SI | NH | Metric |
801 +----------------------------------+
802 | 10 | 3 | 10.1.1.1 | 1 |
803 | | | 10.1.1.2 | 1 |
804 | | | | |
805 | 20 | 12 | 192.168.1.1 | 1 |
806 | | | 10.2.2.2 | 1 |
807 | | | | |
808 | 30 | 7 | 10.2.2.3 | 10 |
809 | | | 10.3.3.3 | 5 |
810 +----------------------------------+
811 (encap type omitted for formatting)
813 Figure 14: NSH Weighted Service Path
815 9.2. Mapping NSH to Network Overlay
817 As described above, the mapping of SPI to network topology may result
818 in a single overlay path, or it might result in a more complex
819 topology. Furthermore, the SPIx to overlay mapping occurs at each
820 SFF independently. Any combination of topology selection is
821 possible.
823 Examples of mapping for a topology:
825 1. Next SF is located at SFFb with locator 10.1.1.1
826 SFFa mapping: SPI=10 --> VXLAN-gpe, dst-ip: 10.1.1.1
828 2. Next SF is located at SFFc with multiple locator for load
829 distribution purposes:
830 SFFb mapping: SPI=10 --> VXLAN-gpe, dst_ip:10.2.2.1, 10.2.2.2,
831 10.2.2.3, equal cost
833 3. Next SF is located at SFFd with two path to SFFc, one for
834 redundancy:
835 SFFc mapping: SPI=10 --> VXLAN-gpe, dst_ip:10.1.1.1 cost=10,
836 10.1.1.2, cost=20
838 In the above example, each SFF makes an independent decision about
839 the network overlay path and policy for that path. In other words,
840 there is no a priori mandate about how to forward packets in the
841 network (only the order of services that must be traversed).
843 The network operator retains the ability to engineer the overlay
844 paths as required. For example, the overlay path between service
845 functions forwarders may utilize traffic engineering, QoS marking, or
846 ECMP, without requiring complex configuration and network protocol
847 support to be extended to the service path explicitly. In other
848 words, the network operates as expected, and evolves as required, as
849 does the service function plane.
851 9.3. Service Plane Visibility
853 The SPI and SI serve an important function for visibility into the
854 service topology. An operator can determine what service path a
855 packet is "on", and its location within that path simply by viewing
856 the NSH information (packet capture, IPFIX, etc.). The information
857 can be used for service scheduling and placement decisions,
858 troubleshooting and compliance verification.
860 9.4. Service Graphs
862 In some cases, a service path is exactly that -- a linear list of
863 service functions that must be traversed. However, increasingly, the
864 "path" is actually a true directed graph. Furthermore, within a
865 given service topology several directed graphs may exist with packets
866 moving between graphs based on non-initial classification (usually
867 performed by a service function). Note: strictly speaking a path is
868 a form of graph; the intent is to distinguish between a directed
869 graph and a path.
871 ,---. ,---. ,---.
872 / \ / \ / \
873 ( SF2 ) ( SF7 ) ( SF3 )
874 ,------\ +. \ / \ /
875 ; |---' `-. `---'\ `-+-'
876 | : : \ ;
877 | \ | : ;
878 ,-+-. `. ,+--. : |
879 / \ '---+ \ \ ;
880 ( SF1 ) ( SF6 ) \ /
881 \ / \ +--. : /
882 `---' `---' `-. ,-+-. /
883 `+ +'
884 ( SF4 )
885 \ /
886 `---'
888 Figure 15: Service Graph Example
890 The SPI/SI combination provides a simple representation of a directed
891 graph, the SPI represents a graph ID; and the SI a node ID. The
892 service topology formed by SPI/SI support cycles, weighting, and
893 alternate topology selection, all within the service plane. The
894 realization of the network topology occurs as described above: SPI/ID
895 mapping to an appropriate transport and associated next network hops.
897 NSH-aware services receive the entire header, including the SPI/SI.
898 An SF can now, based on local policy, alter the SPI, which in turn
899 effects both the service graph, and in turn the selection of overlay
900 at the SFF. The figure below depicts the policy associated with the
901 graph in Figure 14 above. Note: this illustrates multiple graphs and
902 their representation; it does not depict the use of metadata within a
903 single service function graph.
905 +---------------------------------------------------------------------+
906 | SPI: 21 Bob: SF7 |
907 | SPI: 20 Bad : SF2 --> SF6 --> SF4 |
908 |SPI: 10 SF1 --> SF2 --> SF6 SPI: 22 Alice: SF3 |
909 | SPI: 30 Good: SF4 |
910 | SPI:31 Bob: SF7 |
911 | SPI:32 Alice: SF3 |
912 +---------------------------------------------------------------------+
914 Figure 16: Service Graphs Using SPI
916 This example above does not show the mapping of the service topology
917 to the network overlay topology. As discussed in the sections above,
918 the overlay selection occurs as per network policy.
920 10. Policy Enforcement with NSH
922 10.1. NSH Metadata and Policy Enforcement
924 As described in Section 3, NSH provides the ability to carry metadata
925 along a service path. This metadata may be derived from several
926 sources, common examples include:
928 Network nodes: Information provided by network nodes can indicate
929 network-centric information (such as VRF or tenant) that may be
930 used by service functions, or conveyed to another network node
931 post-service pathing.
933 External (to the network) systems: External systems, such as
934 orchestration systems, often contain information that is valuable
935 for service function policy decisions. In most cases, this
936 information cannot be deduced by network nodes. For example, a
937 cloud orchestration platform placing workloads "knows" what
938 application is being instantiated and can communicate this
939 information to all NSH nodes via metadata.
941 Service functions: Service functions often perform very detailed
942 and valuable classification. In some cases they may terminate,
943 and be able to inspect encrypted traffic. SFs may update, alter
944 or impose metadata information.
946 Regardless of the source, metadata reflects the "result" of
947 classification. The granularity of classification may vary. For
948 example, a network switch might only be able to classify based on a
949 5-tuple, whereas, a service function may be able to inspect
950 application information. Regardless of granularity, the
951 classification information can be represented in NSH.
953 Once the data is added to NSH, it is carried along the service path,
954 NSH-aware SFs receive the metadata, and can use that metadata for
955 local decisions and policy enforcement. The following two examples
956 highlight the relationship between metadata and policy:
958 +-------------------------------------------------+
959 | ,---. ,---. ,---. |
960 | / \ / \ / \ |
961 | ( SCL )-------->( SF1 )--------->( SF2 ) |
962 | \ / \ / \ / |
963 | `---' `---' `---' |
964 |5-tuple: Permit Inspect |
965 |Tenant A Tenant A AppY |
966 |AppY |
967 +-------------------------------------------------+
969 Figure 17: Metadata and Policy
971 +-------------------------------------------------+
972 | ,---. ,---. ,---. |
973 | / \ / \ / \ |
974 | ( SCL )-------->( SF1 )--------->( SF2 ) |
975 | \ / \ / \ / |
976 | `-+-' `---' `---' |
977 | | Permit Deny AppZ |
978 | +---+---+ employees |
979 | | | |
980 | +-------+ |
981 | external |
982 | system: |
983 | Employee |
984 | App Z |
985 +-------------------------------------------------+
987 Figure 18: External Metadata and Policy
989 In both of the examples above, the service functions perform policy
990 decisions based on the result of the initial classification: the SFs
991 did not need to perform re-classification, rather they relied on a
992 antecedent classification for local policy enforcement.
994 10.2. Updating/Augmenting Metadata
996 Post-initial metadata imposition (typically performed during initial
997 service path determination), metadata may be augmented or updated:
999 1. Metadata Augmentation: Information may be added to NSH's existing
1000 metadata, as depicted in Figure 18. For example, if the initial
1001 classification returns the tenant information, a secondary
1002 classification (perhaps a DPI or SLB) may augment the tenant
1003 classification with application information. The tenant
1004 classification is still valid and present, but additional
1005 information has been added to it.
1007 2. Metadata Update: Subsequent classifiers may update the initial
1008 classification if it is determined to be incorrect or not
1009 descriptive enough. For example, the initial classifier adds
1010 metadata that describes the trafic as "internet" but a security
1011 service function determines that the traffic is really "attack".
1012 Figure 19 illustrates an example of updating metadata.
1014 +-------------------------------------------------+
1015 | ,---. ,---. ,---. |
1016 | / \ / \ / \ |
1017 | ( SCL )-------->( SF1 )--------->( SF2 ) |
1018 | \ / \ / \ / |
1019 | `-+-' `---' `---' |
1020 | | Inspect Deny |
1021 | +---+---+ employees employee+ |
1022 | | | Class=AppZ appZ |
1023 | +-------+ |
1024 | external |
1025 | system: |
1026 | Employee |
1027 | |
1028 +-------------------------------------------------+
1030 Figure 19: Metadata Augmentation
1032 +-------------------------------------------------+
1033 | ,---. ,---. ,---. |
1034 | / \ / \ / \ |
1035 | ( SCL )-------->( SF1 )--------->( SF2 ) |
1036 | \ / \ / \ / |
1037 | `---' `---' `---' |
1038 |5-tuple: Inspect Deny |
1039 |Tenant A Tenant A attack |
1040 | --> attack |
1041 +-------------------------------------------------+
1043 Figure 20: Metadata Update
1045 10.3. Service Path ID and Metadata
1047 Metadata information may influence the service path selection since
1048 the service path identifier can represent the result of
1049 classification. A given SPI can represent all or some of the
1050 metadata, and be updated based on metadata classification results.
1051 This relationship provides the ability to create a dynamic services
1052 plane based on complex classification without requiring each node to
1053 be capable of such classification, or requiring a coupling to the
1054 network topology. This yields service graph functionality as
1055 described in Section 9.4. Figure 20 illustrates an example of this
1056 behavior.
1058 +----------------------------------------------------+
1059 | ,---. ,---. ,---. |
1060 | / \ / \ / \ |
1061 | ( SCL )-------->( SF1 )--------->( SF2 ) |
1062 | \ / \ / \ / |
1063 | `---' `---' \ `---' |
1064 |5-tuple: Inspect \ Original |
1065 |Tenant A Tenant A \ next SF |
1066 | --> DoS \ |
1067 | \ |
1068 | ,---. |
1069 | / \ |
1070 | ( SF10 ) |
1071 | \ / |
1072 | `---' |
1073 | DoS |
1074 | "Scrubber" |
1075 +----------------------------------------------------+
1077 Figure 21: Path ID and Metadata
1079 Specific algorithms for mapping metadata to an SPI are outside the
1080 scope of this draft.
1082 11. NSH Encapsulation Examples
1084 11.1. GRE + NSH
1086 IPv4 Packet:
1087 +----------+--------------------+--------------------+
1088 |L2 header | L3 header, proto=47|GRE header,PT=0x894F|
1089 +----------+--------------------+--------------------+
1090 --------------+----------------+
1091 NSH, NP=0x1 |original packet |
1092 --------------+----------------+
1094 L2 Frame:
1095 +----------+--------------------+--------------------+
1096 |L2 header | L3 header, proto=47|GRE header,PT=0x894F|
1097 +----------+--------------------+--------------------+
1098 ---------------+---------------+
1099 NSH, NP=0x3 |original frame |
1100 ---------------+---------------+
1102 Figure 22: GRE + NSH
1104 11.2. VXLAN-gpe + NSH
1106 IPv4 Packet:
1107 +----------+------------------------+---------------------+
1108 |L2 header | IP + UDP dst port=4790 |VXLAN-gpe NP=0x4(NSH)|
1109 +----------+------------------------+---------------------+
1110 --------------+----------------+
1111 NSH, NP=0x1 |original packet |
1112 --------------+----------------+
1114 L2 Frame:
1115 +----------+------------------------+---------------------+
1116 |L2 header | IP + UDP dst port=4790 |VXLAN-gpe NP=0x4(NSH)|
1117 +----------+------------------------+---------------------+
1118 ---------------+---------------+
1119 NSH,NP=0x3 |original frame |
1120 ---------------+---------------+
1122 Figure 23: VXLAN-gpe + NSH
1124 11.3. Ethernet + NSH
1126 IPv4 Packet:
1127 +-------------------------------+---------------+--------------------+
1128 |Outer Ethernet, ET=0x894F | NSH, NP = 0x1 | original IP Packet |
1129 +-------------------------------+---------------+--------------------+
1131 L2 Frame:
1132 +-------------------------------+---------------+----------------+
1133 |Outer Ethernet, ET=0x894F | NSH, NP = 0x3 | original frame |
1134 +-------------------------------+---------------+----------------+
1136 Figure 24: Ethernet + NSH
1138 12. Security Considerations
1140 As with many other protocols, NSH data can be spoofed or otherwise
1141 modified. In many deployments, NSH will be used in a controlled
1142 environment, with trusted devices (e.g. a data center) thus
1143 mitigating the risk of unauthorized header manipulation.
1145 NSH is always encapsulated in a transport protocol and therefore,
1146 when required, existing security protocols that provide authenticity
1147 (e.g. RFC 2119 [RFC6071]) can be used.
1149 Similarly if confidentiality is required, existing encryption
1150 protocols can be used in conjunction with encapsulated NSH.
1152 13. Open Items for WG Discussion
1154 1. MD type 1 metadata semantics specifics
1156 2. Bypass bit in NSH.
1158 3. Rendered Service Path ID (RSPID).
1160 14. Contributors
1162 The following people are active contributors to this document and
1163 have provided review, content and concepts (listed alphabetically by
1164 surname):
1166 Andrew Dolganow
1167 Alcaltel-Lucent
1168 Email: andrew.dolganow@alcatel-lucent.com
1170 Rex Fernando
1171 Cisco Systems
1172 Email: rex@cisco.com
1174 Praveen Muley
1175 Alcaltel-Lucent
1176 Email: praveen.muley@alcatel-lucent.com
1178 Navindra Yadav
1179 Cisco Systems
1180 Email: nyadav@cisco.com
1182 15. Acknowledgments
1184 The authors would like to thank Nagaraj Bagepalli, Abhijit Patra, Ron
1185 Parker, Peter Bosch, Darrel Lewis, Pritesh Kothari, Tal Mizrahi and
1186 Ken Gray for their detailed review, comments and contributions.
1188 A special thank you goes to David Ward and Tom Edsall for their
1189 guidance and feedback.
1191 Additionally the authors would like to thank Carlos Pignataro and
1192 Larry Kreeger for their invaluable ideas and contributions which are
1193 reflected throughout this draft.
1195 16. IANA Considerations
1197 16.1. NSH EtherType
1199 An IEEE EtherType, 0x894F, has been allocated for NSH.
1201 16.2. Network Service Header (NSH) Parameters
1203 IANA is requested to create a new "Network Service Header (NSH)
1204 Parameters" registry. The following sub-sections request new
1205 registries within the "Network Service Header (NSH) Parameters "
1206 registry.
1208 16.2.1. NSH Base Header Reserved Bits
1210 There are ten bits at the beginning of the NSH Base Header. New bits
1211 are assigned via Standards Action [RFC5226].
1213 Bits 0-1 - Version
1214 Bit 2 - OAM (O bit)
1215 Bits 2-9 - Reserved
1217 16.2.2. MD Type Registry
1219 IANA is requested to set up a registry of "MD Types". These are
1220 8-bit values. MD Type values 0, 1, 2, 254, and 255 are specified in
1221 this document. Registry entries are assigned by using the "IETF
1222 Review" policy defined in RFC 5226 [RFC5226].
1224 +---------+--------------+---------------+
1225 | MD Type | Description | Reference |
1226 +---------+--------------+---------------+
1227 | 0 | Reserved | This document |
1228 | | | |
1229 | 1 | NSH | This document |
1230 | | | |
1231 | 2 | NSH | This document |
1232 | | | |
1233 | 3..253 | Unassigned | |
1234 | | | |
1235 | 254 | Experiment 1 | This document |
1236 | | | |
1237 | 255 | Experiment 2 | This document |
1238 +---------+--------------+---------------+
1240 Table 1
1242 16.2.3. TLV Class Registry
1244 IANA is requested to set up a registry of "TLV Types". These are 16-
1245 bit values. Registry entries are assigned by using the "IETF Review"
1246 policy defined in RFC 5226 [RFC5226].
1248 16.2.4. NSH Base Header Next Protocol
1250 IANA is requested to set up a registry of "Next Protocol". These are
1251 8-bit values. Next Protocol values 0, 1, 2 and 3 are defined in this
1252 draft. New values are assigned via Standards Action [RFC5226].
1254 +---------------+-------------+---------------+
1255 | Next Protocol | Description | Reference |
1256 +---------------+-------------+---------------+
1257 | 0 | Reserved | This document |
1258 | | | |
1259 | 1 | IPv4 | This document |
1260 | | | |
1261 | 2 | IPv6 | This document |
1262 | | | |
1263 | 3 | Ethernet | This document |
1264 | | | |
1265 | 4..253 | Unassigned | |
1266 +---------------+-------------+---------------+
1268 Table 2
1270 17. References
1272 17.1. Normative References
1274 [RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791,
1275 September 1981.
1277 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
1278 Requirement Levels", BCP 14, RFC 2119, March 1997.
1280 17.2. Informative References
1282 [RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P.
1283 Traina, "Generic Routing Encapsulation (GRE)", RFC 2784,
1284 March 2000.
1286 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
1287 IANA Considerations Section in RFCs", BCP 26, RFC 5226,
1288 May 2008.
1290 [RFC6071] Frankel, S. and S. Krishnan, "IP Security (IPsec) and
1291 Internet Key Exchange (IKE) Document Roadmap", RFC 6071,
1292 February 2011.
1294 [SFC-PS] Quinn, P., Ed. and T. Nadeau, Ed., "Service Function
1295 Chaining Problem Statement", 2014, .
1299 [SFC-arch]
1300 Quinn, P., Ed. and J. Halpern, Ed., "Service Function
1301 Chaining (SFC) Architecture", 2014,
1302 .
1304 [VXLAN-gpe]
1305 Quinn, P., Agarwal, P., Kreeger, L., Lewis, D., Maino, F.,
1306 Yong, L., Xu, X., Elzur, U., and P. Garg, "Generic
1307 Protocol Extension for VXLAN",
1308 .
1310 [dcalloc] Guichard, J., Smith, M., and S. Kumar, "Network Service
1311 Header (NSH) Context Header Allocation (Data Center)",
1312 2014, .
1315 [moballoc]
1316 Napper, J. and S. Kumar, "NSH Context Header Allocation --
1317 Mobility", 2014, .
1320 Authors' Addresses
1322 Paul Quinn
1323 Cisco Systems, Inc.
1325 Email: paulq@cisco.com
1327 Jim Guichard
1328 Cisco Systems, Inc.
1330 Email: jguichar@cisco.com
1332 Surendra Kumar
1333 Cisco Systems, Inc.
1335 Email: smkumar@cisco.com
1337 Michael Smith
1338 Cisco Systems, Inc.
1340 Email: michsmit@cisco.com
1342 Wim Henderickx
1343 Alcatel-Lucent
1345 Email: wim.henderickx@alcatel-lucent.com
1347 Tom Nadeau
1348 Brocade
1350 Email: tnadeau@lucidvision.com
1352 Puneet Agarwal
1354 Email: puneet@acm.org
1356 Rajeev Manur
1357 Broadcom
1359 Email: rmanur@broadcom.com
1360 Abhishek Chauhan
1361 Citrix
1363 Email: Abhishek.Chauhan@citrix.com
1365 Joel Halpern
1366 Ericsson
1368 Email: joel.halpern@ericsson.com
1370 Sumandra Majee
1371 F5
1373 Email: S.Majee@F5.com
1375 Uri Elzur
1376 Intel
1378 Email: uri.elzur@intel.com
1380 David Melman
1381 Marvell
1383 Email: davidme@marvell.com
1385 Pankaj Garg
1386 Microsoft
1388 Email: Garg.Pankaj@microsoft.com
1390 Brad McConnell
1391 Rackspace
1393 Email: bmcconne@rackspace.com
1395 Chris Wright
1396 Red Hat Inc.
1398 Email: chrisw@redhat.com
1399 Kevin Glavin
1400 Riverbed
1402 Email: kevin.glavin@riverbed.com
1404 Hong (Cathy) Zhang
1405 Huawei US R&D
1407 Email: cathy.h.zhang@huawei.com
1409 Louis Fourie
1410 Huawei US R&D
1412 Email: louis.fourie@huawei.com
1414 Ron Parker
1415 Affirmed Networks
1417 Email: ron_parker@affirmednetworks.com
1419 Myo Zarny
1420 Goldman Sachs
1422 Email: myo.zarny@gs.com