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Checking references for intended status: Experimental ---------------------------------------------------------------------------- == Outdated reference: A later version (-06) exists of draft-bernardos-sfc-distributed-control-04 == Outdated reference: A later version (-10) exists of draft-bernardos-sfc-fog-ran-09 Summary: 0 errors (**), 0 flaws (~~), 3 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 SFC WG CJ. Bernardos 3 Internet-Draft UC3M 4 Intended status: Experimental A. Mourad 5 Expires: March 14, 2022 InterDigital 6 September 10, 2021 8 NSH extensions for local distributed SFC control 9 draft-bernardos-sfc-nsh-distributed-control-03 11 Abstract 13 Service function chaining (SFC) allows the instantiation of an 14 ordered set of service functions and subsequent "steering" of traffic 15 through them. In order to set up and maintain SFC instances, a 16 control plane is required, which typically is centralized. In 17 certain environments, such as fog computing ones, such centralized 18 control might not be feasible, calling for distributed SFC control 19 solutions. This document specifies several NSH extensions to provide 20 in-band SFC control signaling. 22 Status of This Memo 24 This Internet-Draft is submitted in full conformance with the 25 provisions of BCP 78 and BCP 79. 27 Internet-Drafts are working documents of the Internet Engineering 28 Task Force (IETF). Note that other groups may also distribute 29 working documents as Internet-Drafts. The list of current Internet- 30 Drafts is at https://datatracker.ietf.org/drafts/current/. 32 Internet-Drafts are draft documents valid for a maximum of six months 33 and may be updated, replaced, or obsoleted by other documents at any 34 time. It is inappropriate to use Internet-Drafts as reference 35 material or to cite them other than as "work in progress." 37 This Internet-Draft will expire on March 14, 2022. 39 Copyright Notice 41 Copyright (c) 2021 IETF Trust and the persons identified as the 42 document authors. All rights reserved. 44 This document is subject to BCP 78 and the IETF Trust's Legal 45 Provisions Relating to IETF Documents 46 (https://trustee.ietf.org/license-info) in effect on the date of 47 publication of this document. Please review these documents 48 carefully, as they describe your rights and restrictions with respect 49 to this document. Code Components extracted from this document must 50 include Simplified BSD License text as described in Section 4.e of 51 the Trust Legal Provisions and are provided without warranty as 52 described in the Simplified BSD License. 54 Table of Contents 56 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 57 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 58 3. Local SFC control signaling extending NSH . . . . . . . . . . 5 59 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 60 5. Security Considerations . . . . . . . . . . . . . . . . . . . 8 61 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8 62 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 63 7.1. Normative References . . . . . . . . . . . . . . . . . . 8 64 7.2. Informative References . . . . . . . . . . . . . . . . . 8 65 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 67 1. Introduction 69 Virtualization of functions provides operators with tools to deploy 70 new services much faster, as compared to the traditional use of 71 monolithic and tightly integrated dedicated machinery. As a natural 72 next step, mobile network operators need to re-think how to evolve 73 their existing network infrastructures and how to deploy new ones to 74 address the challenges posed by the increasing customers' demands, as 75 well as by the huge competition among operators. All these changes 76 are triggering the need for a modification in the way operators and 77 infrastructure providers operate their networks, as they need to 78 significantly reduce the costs incurred in deploying a new service 79 and operating it. Some of the mechanisms that are being considered 80 and already adopted by operators include: sharing of network 81 infrastructure to reduce costs, virtualization of core servers 82 running in data centers as a way of supporting their load-aware 83 elastic dimensioning, and dynamic energy policies to reduce the 84 monthly electricity bill. However, this has proved to be tough to 85 put in practice, and not enough. Indeed, it is not easy to deploy 86 new mechanisms in a running operational network due to the high 87 dependency on proprietary (and sometime obscure) protocols and 88 interfaces, which are complex to manage and often require configuring 89 multiple devices in a decentralized way. 91 Service Functions are widely deployed and essential in many networks. 92 These Service Functions provide a range of features such as security, 93 WAN acceleration, and server load balancing. Service Functions may 94 be instantiated at different points in the network infrastructure 95 such as data center, the WAN, the RAN, and even on mobile nodes. 97 Service functions (SFs), also referred to as VNFs, or just functions, 98 are hosted on compute, storage and networking resources. The hosting 99 environment of a function is called Service Function Provider or 100 NFVI-PoP (using ETSI NFV terminology). 102 Services are typically formed as a composition of SFs (VNFs), with 103 each SF providing a specific function of the whole service. Services 104 also referred to as Network Services (NS), according to ETSI 105 terminology. 107 With the arrival of virtualization, the deployment model for service 108 function is evolving to one where the traffic is steered through the 109 functions wherever they are deployed (functions do not need to be 110 deployed in the traffic path anymore). For a given service, the 111 abstracted view of the required service functions and the order in 112 which they are to be applied is called a Service Function Chain 113 (SFC). An SFC is instantiated through selection of specific service 114 function instances on specific network nodes to form a service graph: 115 this is called a Service Function Path (SFP). The service functions 116 may be applied at any layer within the network protocol stack 117 (network layer, transport layer, application layer, etc.). 119 The concept of fog computing has emerged driven by the Internet of 120 Things (IoT) due to the need of handling the data generated from the 121 end-user devices. The term fog is referred to any networked 122 computational resource in the continuum between things and cloud. A 123 fog node may therefore be an infrastructure network node such as an 124 eNodeB or gNodeB, an edge server, a customer premises equipment 125 (CPE), or even a user equipment (UE) terminal node such as a laptop, 126 a smartphone, or a computing unit on-board a vehicle, robot or drone. 128 In fog computing, the functions composing an SFC are hosted on 129 resources that are inherently heterogeneous, volatile and mobile 130 [I-D.bernardos-sfc-fog-ran]. This means that resources might appear 131 and disappear, and the connectivity characteristics between these 132 resources may also change dynamically. These scenarios call for 133 distributed SFC control solutions, where there are SFC pseudo 134 controllers, enabling autonomous SFC self-orchestration capabilities. 135 The concept of SFC pseudo controller (P-CTRL) is described in 136 [I-D.bernardos-sfc-distributed-control], as well different procedures 137 for their discovery and initialization. 139 This document specifies several NSH extensions to provide in-band SFC 140 control signaling. 142 2. Terminology 144 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 145 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 146 document are to be interpreted as described in [RFC2119]. 148 The following terms used in this document are defined by the IETF in 149 [RFC7665]: 151 Service Function (SF): a function that is responsible for specific 152 treatment of received packets (e.g., firewall, load balancer). 154 Service Function Chain (SFC): for a given service, the abstracted 155 view of the required service functions and the order in which they 156 are to be applied. This is somehow equivalent to the Network 157 Function Forwarding Graph (NF-FG) at ETSI. 159 Service Function Forwarder (SFF): A service function forwarder is 160 responsible for forwarding traffic to one or more connected 161 service functions according to information carried in the SFC 162 encapsulation, as well as handling traffic coming back from the 163 SF. 165 SFI: SF instance. 167 Service Function Path (SFP): the selection of specific service 168 function instances on specific network nodes to form a service 169 graph through which an SFC is instantiated. 171 The following terms are used in this document: 173 SFC Pseudo Controller (P-CTRL): logical entity 174 [I-D.bernardos-sfc-distributed-control], complementing the SFC 175 controller/orchestrator found in current architectures and 176 deployments. It is service specific, meaning that it is defined 177 and meaningful in the context of a given network service. 178 Compared to existing SFC controllers/orchestrators, which manage 179 multiple SFCs instantiated over a common infrastructure, pseudo 180 controllers are constrained to service specific lifecycle 181 management. 183 SFC Central Controller (C-CTRL): central control plane logical 184 entity in charge of configuring and managing the SFC components 185 [RFC7665]. 187 3. Local SFC control signaling extending NSH 189 o 190 node B | 191 +--------|-+ F1+-.-.-+F2+-.-.-+F3 SFC 192 | ........ | 193 | |P-CTRL| | 194 | ........ | 195 +-.-.-+F2 | 196 o / +---+------+ ________ 197 | . . _( )_ 198 +--------|-+ / / _( +--------+ )_ 199 | | . . (_ | C-CTRL | _) 200 | | / / (_+--------+_) 201 | |. | (________) 202 | +-.-./ . 203 | F1 | | ( (oo) ) 204 +----------+ . o /\ ........ 205 node A | | /\/\ |P-CTRL| 206 +-----.--|-+ /\/\/\........ 207 | | | /\/ \/\ F3 208 | . | node D 209 | | | 210 | + | 211 | | 212 +----------+ 213 node C 215 Figure 1: Example SFC scenario 217 Figure 1 shows an exemplary scenario to show the use of the new NSH 218 extensions. In this scenario, there is no mobility, so nodes are not 219 moving out of radio coverage. In this scenario, at a given point in 220 time the service demands increase, which requires F2 (running at node 221 B) and F3 (running at node D) to have more resources allocated, as 222 otherwise the service would not meet the required SLA. This is 223 detected by the P-CTRL through service-specific local OAM monitoring. 224 Once detected the need of scaling up the resources at nodes B and D, 225 P-CTRL notifies this through in-band signaling in the actual data 226 packets processed by the SFC. This is shown in Figure 2. Note that 227 the use of in-band signaling provides a more efficient way of 228 conveying the signaling, as well as supports multiple NS lifecycle 229 management operations (even addressing different nodes) to be 230 conveyed in a single message. 232 +--------+ +--------+ +--------+ 233 | F1@A | | F2@B | | F3@D | 234 +--------+ +--------+ +--------+ 236 +--------+ +--------+ +--------+ 237 |Transp. | |Transp. | |Transp. | 238 | header | | header | | header | 239 +--------+ +--------+ +--------+ 240 | NSH | | NSH | | NSH | 241 | header | | header | | header | 242 | F3@D | | F3@D | | F3@D | 243 |scale up| |scale up| |scale up| 244 | F2@B | | F2@B | | | 245 |scale up| |scale up| | | 246 +--------+ +--------+ +--------+ +--------+ +--------+ 247 | Packet | | Packet | | Packet | | Packet | | Packet | 248 +--------+ +--------+ +--------+ +--------+ +--------+ 249 ===> ===> ===> ===> ===> 251 Figure 2: In-band NS lifecycle management signaling extending NSH 253 The NS lifecycle management commands conveyed in the NSH are 254 transported as a new NSH metadata (MD) type (e.g., Type 3, as current 255 NSH specifications only support 2 types), as shown next: 257 0 1 2 3 258 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 1 259 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 260 |Ver|O|U| TTL | Length |U|U|U|U|MD Type| Next Protocol | 261 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 262 | Service Path Identifier | Service Index | 263 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 264 | | 265 ~ Variable-Length NS lifecycle management commands ~ 266 | | 267 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 269 The format of the new variable-length field for NS lifecycle 270 management commands is shown next: 272 0 1 2 3 273 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 1 274 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 275 | NS lifecycle cmd | Type |U| Length | 276 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 277 | Variable-Length Metadata | 278 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 279 o NS lifecycle cmd: the NS lifecycle management command. This is a 280 non-limiting list of the commands: 282 * Scale in. 284 * Scale out. 286 * Scale up. 288 * Scale down. 290 * Instantiate function. 292 * Terminate function. 294 * Configure function. 296 * Upgrade function. 298 * Update function. 300 * Update function. 302 * Onboard VNFD. 304 * Onboard OAMD. 306 * Sync state. 308 * Request to overcome CTRL. 310 * CTRL activation. 312 o Type: indicates the explicit type of command carried out. This 313 depends on the orchestration framework implementation. 315 o Unassigned bit: one unassigned bit is available for future use. 316 This bit MUST NOT be set, and it MUST be ignored on receipt. 318 o Unassigned bit: one unassigned bit is available for future use. 319 This bit MUST NOT be set, and it MUST be ignored on receipt. 321 4. IANA Considerations 323 N/A. 325 5. Security Considerations 327 TBD. 329 6. Acknowledgments 331 The work in this draft has been partially supported by the H2020 332 5Growth (Grant 856709) and 5G-DIVE projects (Grant 859881). 334 7. References 336 7.1. Normative References 338 [I-D.bernardos-sfc-distributed-control] 339 Bernardos, C. J. and A. Mourad, "Distributed SFC control 340 for fog environments", draft-bernardos-sfc-distributed- 341 control-04 (work in progress), July 2021. 343 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 344 Requirement Levels", BCP 14, RFC 2119, 345 DOI 10.17487/RFC2119, March 1997, 346 . 348 7.2. Informative References 350 [I-D.bernardos-sfc-fog-ran] 351 Bernardos, C. J., Rahman, A., and A. Mourad, "Service 352 Function Chaining Use Cases in Fog RAN", draft-bernardos- 353 sfc-fog-ran-09 (work in progress), March 2021. 355 [RFC7665] Halpern, J., Ed. and C. Pignataro, Ed., "Service Function 356 Chaining (SFC) Architecture", RFC 7665, 357 DOI 10.17487/RFC7665, October 2015, 358 . 360 Authors' Addresses 362 Carlos J. Bernardos 363 Universidad Carlos III de Madrid 364 Av. Universidad, 30 365 Leganes, Madrid 28911 366 Spain 368 Phone: +34 91624 6236 369 Email: cjbc@it.uc3m.es 370 URI: http://www.it.uc3m.es/cjbc/ 371 Alain Mourad 372 InterDigital Europe 374 Email: Alain.Mourad@InterDigital.com 375 URI: http://www.InterDigital.com/