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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 TEAS Working Group Daniele Ceccarelli (Ed) 2 Internet Draft Ericsson 3 Intended status: Informational Young Lee (Ed) 4 Expires: January 2017 Huawei 6 October 25, 2016 8 Framework for Abstraction and Control of Traffic Engineered Networks 10 draft-ietf-teas-actn-framework-01 12 Status of this Memo 14 This Internet-Draft is submitted to IETF in full conformance with 15 the provisions of BCP 78 and BCP 79. 17 Internet-Drafts are working documents of the Internet Engineering 18 Task Force (IETF), its areas, and its working groups. Note that 19 other groups may also distribute working documents as Internet- 20 Drafts. 22 Internet-Drafts are draft documents valid for a maximum of six 23 months and may be updated, replaced, or obsoleted by other documents 24 at any time. It is inappropriate to use Internet-Drafts as 25 reference material or to cite them other than as "work in progress." 27 The list of current Internet-Drafts can be accessed at 28 http://www.ietf.org/ietf/1id-abstracts.txt 30 The list of Internet-Draft Shadow Directories can be accessed at 31 http://www.ietf.org/shadow.html. 33 This Internet-Draft will expire on January 25, 2017. 35 Copyright Notice 37 Copyright (c) 2016 IETF Trust and the persons identified as the 38 document authors. All rights reserved. 40 This document is subject to BCP 78 and the IETF Trust's Legal 41 Provisions Relating to IETF Documents 42 (http://trustee.ietf.org/license-info) in effect on the date of 43 publication of this document. Please review these documents 44 carefully, as they describe your rights and restrictions with 45 respect to this document. Code Components extracted from this 46 document must include Simplified BSD License text as described in 47 Section 4.e of the Trust Legal Provisions and are provided without 48 warranty as described in the Simplified BSD License. 50 Abstract 52 Traffic Engineered networks have a variety of mechanisms to 53 facilitate the 54 separation of the data plane and control plane. They also have a 55 range of management and provisioning protocols to configure and 56 activate network resources. These mechanisms represent key 57 technologies for enabling flexible and dynamic networking. 59 Abstraction of network resources is a technique that can be applied 60 to a single network domain or across multiple domains to create a 61 single virtualized network that is under the control of a network 62 operator or the customer of the operator that actually owns 63 the network resources. 65 This draft provides a framework for Abstraction and Control of 66 Traffic Engineered Networks (ACTN). 68 Table of Contents 70 1. Introduction...................................................3 71 1.1. Terminology...............................................5 72 2. Business Model of ACTN.........................................8 73 2.1. Customers.................................................8 74 2.2. Service Providers........................................10 75 2.3. Network Providers........................................11 76 3. ACTN architecture.............................................12 77 3.1. Customer Network Controller..............................14 78 3.2. Multi Domain Service Coordinator.........................15 79 3.3. Physical Network Controller..............................16 80 3.4. ACTN interfaces..........................................17 81 4. VN creation process...........................................19 82 5. Access Points and Virtual Network Access Points...............20 83 5.1. Dual homing scenario.....................................22 84 6. End point selection & mobility................................23 85 6.1. End point selection & mobility...........................23 86 6.2. Preplanned end point migration...........................24 87 6.3. On the fly end point migration...........................25 89 7. Security......................................................25 90 8. References....................................................25 91 8.1. Informative References...................................25 92 9. Contributors..................................................28 93 Authors' Addresses...............................................28 95 1. Introduction 97 Traffic Engineered networks have a variety of mechanisms to 98 facilitate separation of data plane and control plane including 99 distributed signaling for path setup and protection, centralized 100 path computation for planning and traffic engineering, and a range 101 of management and provisioning protocols to configure and activate 102 network resources. These mechanisms represent key technologies for 103 enabling flexible and dynamic networking. 105 The term Traffic Engineered Network in this draft refers to any 106 connection-oriented network that has the ability of dynamic 107 provisioning, abstracting and orchestrating network resource to the 108 network's clients. Some examples of networks that are in scope of 109 this definition are optical networks, MPLS Transport Profile (MPLS- 110 TP), MPLS Traffic Engineering (MPLS-TE), and other emerging 111 technologies with connection-oriented behavior. 113 One of the main drivers for Software Defined Networking (SDN) is a 114 decoupling of the network control plane from the data plane. This 115 separation of the control plane from the data plane has been already 116 achieved with the development of MPLS/GMPLS [GMPLS] and PCE [PCE] 117 for TE-based transport networks. One of the advantages of SDN is its 118 logically centralized control regime that allows a global view of 119 the underlying network under its control. Centralized control in SDN 120 helps improve network resources utilization compared with 121 distributed network control. For TE-based transport network control, 122 PCE is essentially equivalent to a logically centralized control for 123 path computation function. 125 Two key aspects that need to be solved by SDN are: 127 . Network and service abstraction: Detach the network and service 128 control from underlying technology and help customer express 129 the network as desired by business needs. 131 . Coordination of resources across multiple domains and multiple 132 layers to provide end-to-end services regardless of whether the 133 domains use SDN or not. 135 As networks evolve, the need to provide resource and service 136 abstraction has emerged as a key requirement for operators; this 137 implies in effect the virtualization of network resources so that 138 the network is "sliced" for different tenants shown as a dedicated 139 portion of the network resources 141 Particular attention needs to be paid to the multi-domain case, where 142 Abstraction and Control of Traffic Engineered Networks (ACTN) can 143 facilitate virtual network operation via the creation of a single 144 virtualized network or a seamless service. This supports operators in 145 viewing and controlling different domains (at any dimension: applied 146 technology, administrative zones, or vendor-specific technology 147 islands) as a single virtualized network. 149 Network virtualization refers to allowing the customers of network 150 operators (see Section 2.1) to utilize a certain amount of network 151 resources as if they own them and thus control their allocated 152 resources with higher layer or application processes that enables 153 the resources to be used in the most optimal way. More flexible, 154 dynamic customer control capabilities are added to the traditional 155 VPN along with a customer specific virtual network view. Customers 156 control a view of virtual network resources, specifically allocated 157 to each one of them. This view is called an abstracted network 158 topology. Such a view may be specific to a specific service, the set 159 of consumed resources or to a particular customer. Customer 160 controller of the virtual network is envisioned to support a 161 plethora of distinct applications. This means that there may be a 162 further level of virtualization that provides a view of resources in 163 the customer's virtual network for use by an individual application. 165 The framework described in this draft is named Abstraction and 166 Control of Traffic Engineered Network (ACTN) and facilitates: 168 - Abstraction of the underlying network resources to higher-layer 169 applications and customers [TE-INFO]. 171 - Virtualization of particular underlying resources, whose 172 selection criterion is the allocation of those resources to a 173 particular customer, application or service. [ONF-ARCH] 175 - Slicing infrastructure to connect multiple customers to meet 176 specific customer's service requirements. 178 - Creation of a virtualized environment allowing operators to 179 view and control multi-domain networks into a single 180 virtualized network; 182 - Possibility of providing a customer with virtualized network or 183 services (totally hiding the network). 185 - A virtualization/mapping network function that adapts customer 186 requests to the virtual resources (allocated to them) to the 187 supporting physical network control and performs the necessary 188 mapping, translation, isolation and security/policy 189 enforcement, etc.; This function is often referred to as 190 orchestration. 192 - The presentation of the networks as a virtualized topology to 193 the customers via open and programmable interfaces. This allows 194 for the recursion of controllers in a customer-provider 195 relationship. 197 1.1. Terminology 199 The following terms are used in this document. Some of them are 200 newly defined, some others reference existing definition: 201 - Node: A node is a topological entity describing the "opaque" 202 forwarding aspect of the topological component which represents 203 the opportunity to enable forwarding between points at the edge 204 of the node. It provides the context for instructing the 205 formation, adjustment and removal of the forwarding. A node, in 206 a VN network, can be represented by single physical entity or 207 by a group of nodes moving from physical to virtual network. 209 - Link: A link is a topological entity describing the effective 210 adjacency between two or more forwarding entities, such as two 211 or more nodes. In its basic form (i.e., point-to-point Link) it 212 associates an edge point of a node with an equivalent edge 213 point on another node. Links in virtual network is in fact 214 connectivity, realized by bandwidth engineering between any two 215 nodes meeting certain criteria, for example, redundancy, 216 protection, latency, not tied to any technology specific 217 characteristics like timeslots or wavelengths. The link can be 218 dynamic, realized by a service in underlay, or static. 220 - PNC domain: A PNC domain includes all the resources under the 221 control of a single PNC. It can be composed by different 222 routing domains, administrative domains and different layers. 223 The interconnection between PNC domains can be a link or a 224 node. 226 border 227 ------- link ------- 228 ( )---------( ) 229 - - __ - - 230 ( PNC )+---+( PNC ) 231 ( Domain X ) ( Domain Y ) 232 ( )+---+( ) 233 - - border- - 234 ( ) node ( ) 235 ------- ------- 237 Figure 1 : PNC domain borders 239 - A Virtual Network is a client view (typically a network slice) 240 of the transport network. It is presented by the provider as a 241 set of physical and/or abstracted resources. Depending on the 242 agreement between client and provider various VN operations and 243 VN views are possible. 245 (1) VN Creation - VN could be pre-configured and created via 246 static negotiation between customer and provider. In other 247 cases, VN could also be created dynamically based on the 248 request from the customer with given SLA attributes which 249 satisfy the customer's objectives. 251 (2) Dynamic Operations - VN could be further modified and 252 deleted based on customer request to request changes in the 253 network resources reserved for the customer. The customer can 254 further act upon the virtual network resources to perform E2E 255 tunnel management (set-up/release/modify). These changes will 256 incur subsequent LSP management on the operator's level. 258 (3) VN View - (a) VN can be seen as an (or set of) e2e 259 tunnel(s) from a customer point of view where an e2e tunnel is 260 referred as a VN member. Each VN member (i.e., e2e tunnel) can 261 then be formed by recursive aggregation of lower level paths at 262 a provider level. Such end to end tunnels may comprise of 263 customer end points, access links, intra domain paths and 264 inter-domain link. In this view VN is thus a list of VN 265 members. (b) VN can also be seen as a terms of topology 266 comprising of physical and abstracted nodes and links. The 267 nodes in this case include physical customer end points, border 268 nodes, and internal nodes as well as abstracted nodes. 269 Similarly the links includes physical access, inter-domain and 270 intra-domain links as well as abstracted links. The abstracted 271 nodes and links in this view can be pre-negotiated or created 272 dynamically. 274 - Abstraction is the process of applying policy to the available 275 TE information within a domain, to produce selective 276 information that represents the potential ability to connect 277 across the domain. Thus, abstraction does not necessarily 278 offer all possible connectivity options, but it presents a 279 general view of potential connectivity according to the 280 policies that determine how the domain's administrator wants to 281 allow the domain resources to be used. [RFC7926] 283 - Abstract Link: An abstract link is the representation of the 284 characteristics of a path between two nodes in a domain 285 produced by abstraction. The abstract link is advertised 286 outside that domain as a TE link for use in signaling in other 287 domains. Thus, an abstract link represents the potential to 288 connect between a pair of nodes. [RFC7926] 290 - Abstract Topology: Every lower controller in the provider 291 network, when is representing its network topology to an higher 292 layer, it may want to hide details of the actual network 293 topology. In such case, an abstract topology may be used for 294 this purpose. Abstract topology enhances scalability for the 295 MDSC to operate multi-domain networks 297 - Access link: A link between a customer node and a provider 298 node. 300 - Inter domain link: A link between domains managed by different 301 PNCs. The MDSC is in charge of managing inter-domain links. 303 - Border node: A node whose interfaces belong to different 304 domains. It may be managed by different PNCs or by the MDSC. 306 - Access Point (AP): An access point is defined on an access 307 link. It is used to keep confidentiality between the customer 308 and the provider. It is an identifier shared between the 309 customer and the provider, used to map the end points of the 310 border node in the provider NW. The AP can be used by the 311 customer when requesting connectivity service to the provider. 312 A number of parameters, e.g. available bandwidth, need to be 313 associated to the AP to qualify it. 315 - VN Access Point (VNAP): A VNAP is defined within an AP as part 316 of a given VN and is used to identify the portion of the AP, 317 and hence of the access link) dedicated to a given VN. 319 2. Business Model of ACTN 321 The Virtual Private Network (VPN) [RFC4026] and Overlay Network (ON) 322 models [RFC4208] are built on the premise that one single network 323 provider provides all virtual private or overlay networks to its 324 customers. These models are simple to operate but have some 325 disadvantages in accommodating the increasing need for flexible and 326 dynamic network virtualization capabilities. 328 The ACTN model is built upon entities that reflect the current 329 landscape of network virtualization environments. There are three 330 key entities in the ACTN model [ACTN-PS]: 332 - Customers 333 - Service Providers 334 - Network Providers 336 2.1. Customers 338 Within the ACTN framework, different types of customers may be taken 339 into account depending on the type of their resource needs, on their 340 number and type of access. As example, it is possible to group them 341 into two main categories: 343 Basic Customer: Basic customers include fixed residential users, 344 mobile users and small enterprises. Usually the number of basic 345 customers is high; they require small amounts of resources and are 346 characterized by steady requests (relatively time invariant). A 347 typical request for a basic customer is for a bundle of voice 348 services and internet access. Moreover basic customers do not modify 349 their services themselves; if a service change is needed, it is 350 performed by the provider as proxy and they generally have very few 351 dedicated resources (subscriber drop), with everything else shared 352 on the basis of some SLA, which is usually best-efforts. 354 Advanced Customer: Advanced customers typically include enterprises, 355 governments and utilities. Such customers can ask for both point to 356 point and multipoint connectivity with high resource demand 357 significantly varying in time and from customer to customer. This is 358 one of the reasons why a bundled service offering is not enough and 359 it is desirable to provide each of them with a customized virtual 360 network service. 362 Advanced customers may own dedicated virtual resources, or share 363 resources. They may also have the ability to modify their service 364 parameters within the scope of their virtualized environments. 366 As customers are geographically spread over multiple network 367 provider domains, they have to interface multiple providers and may 368 have to support multiple virtual network services with different 369 underlying objectives set by the network providers. To enable these 370 customers to support flexible and dynamic applications they need to 371 control their allocated virtual network resources in a dynamic 372 fashion, and that means that they need an abstracted view of the 373 topology that spans all of the network providers. 375 ACTN's primary focus is Advanced Customers. 377 Customers of a given service provider can in turn offer a service to 378 other customers in a recursive way. An example of recursiveness with 379 2 service providers is shown below. 381 - Customer (of service B) 382 - Customer (of service A) & Service Provider (of service B) 383 - Service Provider (of service A) 384 - Network Provider 386 +------------------------------------------------------------+ --- 387 | | ^ 388 | Customer (of service B)| . 389 | +--------------------------------------------------------+ | B 390 | | | |--- . 391 | |Customer (of service A) & Service Provider(of service B)| | ^ . 392 | | +---------------------------------------------------+ | | . . 393 | | | | | | . . 394 | | | Service Provider (of service A)| | | A . 395 | | |+------------------------------------------+ | | | . . 396 | | || | | | | . . 397 | | || Network provider| | | | v v 398 | | |+------------------------------------------+ | | |------ 399 | | +---------------------------------------------------+ | | 400 | +--------------------------------------------------------+ | 401 +------------------------------------------------------------+ 403 Figure 2 : Service Recursiveness. 405 2.2. Service Providers 407 Service providers are the providers of virtual network services to 408 their customers. Service providers may or may not own physical 409 network resources. When a service provider is the same as the 410 network provider, this is similar to traditional VPN models. This 411 model works well when the customer maintains a single interface with 412 a single provider. When customer location spans across multiple 413 independent network provider domains, then it becomes hard to 414 facilitate the creation of end-to-end virtual network services with 415 this model. 417 A more interesting case arises when network providers only provide 418 infrastructure while service providers directly interface their 419 customers. In this case, service providers themselves are customers 420 of the network infrastructure providers. One service provider may 421 need to keep multiple independent network providers as its end-users 422 span geographically across multiple network provider domains as 423 shown in Figure 2 where Service Provider A uses resources from 424 Network Provider A and Network Provider B to offer a virtualized 425 network to its customer. 427 Customer X -----------------------------------X 429 Service Provider A X -----------------------------------X 431 Network Provider B X-----------------X 433 Network Provider A X------------------X 435 Figure 3 : A service Provider as Customer of Two Network Providers. 437 The ACTN network model is predicated upon this three tier model and 438 is summarized in Figure 3: 440 +----------------------+ 441 | customer | 442 +----------------------+ 443 | 444 | /\ Service/Customer specific 445 | || Abstract Topology 446 | || 447 +----------------------+ E2E abstract 448 | Service Provider | topology creation 449 +----------------------+ 450 / | \ 451 / | \ Network Topology 452 / | \ (raw or abstract) 453 / | \ 454 +------------------+ +------------------+ +------------------+ 455 |Network Provider 1| |Network Provider 2| |Network Provider 3| 456 +------------------+ +------------------+ +------------------+ 458 Figure 4 : Three tier model. 460 There can be multiple types of service providers. 462 . Data Center providers: can be viewed as a service provider type 463 as they own and operate data center resources to various WAN 464 customers, they can lease physical network resources from 465 network providers. 466 . Internet Service Providers (ISP): can be a service provider of 467 internet services to their customers while leasing physical 468 network resources from network providers. 469 . Mobile Virtual Network Operators (MVNO): provide mobile 470 services to their end-users without owning the physical network 471 infrastructure. 473 2.3. Network Providers 475 Network Providers are the infrastructure providers that own the 476 physical network resources and provide network resources to their 477 customers. The layered model proposed by this draft separates the 478 concerns of network providers and customers, with service providers 479 acting as aggregators of customer requests. 481 3. ACTN architecture 483 This section provides a high-level control and interface model of 484 ACTN. 486 The ACTN architecture, while being aligned with the ONF SDN 487 architecture [ONF-ARCH], is presenting a 3-tiers reference model. It 488 allows for hierarchy and recursiveness not only of SDN controllers 489 but also of traditionally controlled domains. It defines three types 490 of controllers depending on the functionalities they implement. The 491 main functionalities that are identified are: 493 . Multi domain coordination function: This function oversees the 494 specific aspects of the different domains and builds a single 495 abstracted end-to-end network topology in order to coordinate 496 end-to-end path computation and path/service provisioning. 497 Domain sequence path calculation/determination is also a part 498 of this function. 500 . Virtualization/Abstraction function: This function provides an 501 abstracted view of the underlying network resources towards 502 customer, being it the client or a higher level controller 503 entity. It includes network path computation based on customer 504 service connectivity request constraints, based on the global 505 network-wide abstracted topology and the creation of an 506 abstracted view of network slices allocated to each customer, 507 according to customer-specific network objective functions, and 508 to the customer traffic profile. 510 . Customer mapping/translation function: This function is to map 511 customer intent-like commands into network provisioning 512 requests to the Physical Network Controller (PNC) according to 513 business OSS/NMS provisioned static or dynamic policy. 514 Specifically, it provides mapping and translation of customer's 515 service request into a set of parameters that are specific to a 516 network type and technology such that network configuration 517 process is made possible. 519 . Virtual service coordination: This function translates customer 520 service-related information into the virtual network service 521 operations in order to seamlessly operate virtual networks 522 while meeting customer's service requirements. In the context 523 of ACTN, service/virtual service coordination includes a number 524 of service orchestration functions such as multi-destination 525 load balancing, guarantees of service quality, bandwidth and 526 throughput and notification for service fault and performance 527 degradation and so forth. 529 The virtual services that are coordinated under ACTN can be split 530 into two categories: 532 . Service-aware Connectivity Services: This category includes all 533 the network service operations used to provide connectivity 534 between customer end-points while meeting policies and service 535 related constraints. The data model for this category would 536 include topology entities such as virtual nodes, virtual links, 537 adaptation and termination points and service-related entities 538 such as policies and service related constraints. (See Section 539 4.2.2) 541 . Network Function Virtualization Services: These kinds of 542 services are usually setup in NFV (e.g. cloud) providers and 543 require connectivity between a customer site and the NFV 544 provider site (e.g. a data center). These VNF services may 545 include a security function like firewall, a traffic optimizer, 546 the provisioning of storage or computation capacity. In these 547 cases the customer does not care whether the service is 548 implemented in a given data center or another. This allows the 549 network provider divert customer requests where most suitable. 550 This is also known as "end points mobility" case. (See Section 551 4.2.3) 553 The types of controller defined are shown in Figure 4 below and are 554 the following: 556 . CNC - Customer Network Controller 557 . MDSC - Multi Domain Service Coordinator 558 . PNC - Physical Network Controller 560 VPN customer NW Mobile Customer ISP NW service Customer 561 | | | 562 +-------+ +-------+ +-------+ 563 | CNC-A | | CNC-B | | CNC-C | 564 +-------+ +-------+ +-------+ 565 \ | / 566 ----------- |CMI I/F -------------- 567 \ | / 568 +-----------------------+ 569 | MDSC | 570 +-----------------------+ 571 / | \ 572 ------------- |MPI I/F ------------- 573 / | \ 574 +-------+ +-------+ +-------+ 575 | PNC | | PNC | | PNC | 576 +-------+ +-------+ +-------+ 577 | GMPLS / | / \ 578 | trigger / | / \ 579 -------- ---- +-----+ +-----+ \ 580 ( ) ( ) | PNC | | PCE | \ 581 - - ( Phys ) +-----+ +-----+ ----- 582 ( GMPLS ) (Netw) | / ( ) 583 ( Physical ) ---- | / ( Phys. ) 584 ( Network ) ----- ----- ( Net ) 585 - - ( ) ( ) ----- 586 ( ) ( Phys. ) ( Phys ) 587 -------- ( Net ) ( Net ) 588 ----- ----- 590 Figure 5 : ACTN Control Hierarchy 592 3.1. Customer Network Controller 594 A Virtual Network Service is instantiated by the Customer Network 595 Controller via the CMI (CNC-MDSC Interface). As the Customer Network 596 Controller directly interfaces the applications, it understands 597 multiple application requirements and their service needs. It is 598 assumed that the Customer Network Controller and the MDSC have a 599 common knowledge on the end-point interfaces based on their business 600 negotiation prior to service instantiation. End-point interfaces 601 refer to customer-network physical interfaces that connect customer 602 premise equipment to network provider equipment. 604 In addition to abstract networks, ACTN allows to provide the CNC 605 with services. Example of services include connectivity between one 606 of the customer's end points with a given set of resources in a data 607 center from the service provider. 609 3.2. Multi Domain Service Coordinator 611 The MDSC (Multi Domain Service Coordinator) sits between the CNC 612 (the one issuing connectivity requests) and the PNCs (Physical 613 Network Controllersr - the ones managing the physical network 614 resources). The MDSC can be collocated with the PNC, especially in 615 those cases where the service provider and the network provider are 616 the same entity. 618 The internal system architecture and building blocks of the MDSC are 619 out of the scope of ACTN. Some examples can be found in the 620 Application Based Network Operations (ABNO) architecture [ABNO] and 621 the ONF SDN architecture [ONF-ARCH]. 623 The MDSC is the only building block of the architecture that is able 624 to implement all the four ACTN main functionalities, i.e. multi 625 domain coordination function, virtualization/abstraction function, 626 customer mapping function and virtual service coordination. The key 627 point of the MDSC and the whole ACTN framework is detaching the 628 network and service control from underlying technology and help 629 customer express the network as desired by business needs. The MDSC 630 envelopes the instantiation of right technology and network control 631 to meet business criteria. In essence it controls and manages the 632 primitives to achieve functionalities as desired by CNC 633 A hierarchy of MDSCs can be foreseen for scalability and 634 administrative choices. 636 +-------+ +-------+ +-------+ 637 | CNC-A | | CNC-B | | CNC-C | 638 +-------+ +-------+ +-------+ 639 \ | / 640 ---------- | ---------- 641 \ | / 642 +-----------------------+ 643 | MDSC | 644 +-----------------------+ 645 / | \ 646 ---------- | ----------- 647 / | \ 648 +----------+ +----------+ +--------+ 649 | MDSC | | MDSC | | MDSC | 650 +----------+ +----------+ +--------+ 651 | / | / \ 652 | / | / \ 653 +-----+ +-----+ +-----+ +-----+ +-----+ 654 | PNC | | PNC | | PNC | | PNC | | PNC | 655 +-----+ +-----+ +-----+ +-----+ +-----+ 657 Figure 6 : Controller recursiveness 659 A key requirement for allowing recursion of MDSCs is that a single 660 interface needs to be defined both for the north and the south 661 bounds. 662 In order to allow for multi-domain coordination a 1:N relationship 663 must be allowed between MDSCs and between MDSCs and PNCs (i.e. 1 664 parent MDSC and N child MDSC or 1 MDSC and N PNCs). In addition to 665 that it could be possible to have also a M:1 relationship between 666 MDSC and PNC to allow for network resource partitioning/sharing 667 among different customers not necessarily connected to the same MDSC 668 (e.g. different service providers). 670 3.3. Physical Network Controller 672 The Physical Network Controller is the one in charge of configuring 673 the network elements, monitoring the physical topology of the 674 network and passing it, either raw or abstracted, to the MDSC. 676 The internal architecture of the PNC, his building blocks and the 677 way it controls its domain, are out of the scope of ACTN. Some 678 examples can be found in the Application Based Network Operations 679 (ABNO) architecture [ABNO] and the ONF SDN architecture [ONF-ARCH] 680 The PNC, in addition to being in charge of controlling the physical 681 network, is able to implement two of the four ACTN main 682 functionalities: multi domain coordination function and 683 virtualization/abstraction function 684 A hierarchy of PNCs can be foreseen for scalability and 685 administrative choices. 687 3.4. ACTN interfaces 689 To allow virtualization and multi domain coordination, the network 690 has to provide open, programmable interfaces, in which customer 691 applications can create, replace and modify virtual network 692 resources and services in an interactive, flexible and dynamic 693 fashion while having no impact on other customers. Direct customer 694 control of transport network elements and virtualized services is 695 not perceived as a viable proposition for transport network 696 providers due to security and policy concerns among other reasons. 697 In addition, as discussed in the previous section, the network 698 control plane for transport networks has been separated from data 699 plane and as such it is not viable for the customer to directly 700 interface with transport network elements. 702 Figure 5 depicts a high-level control and interface architecture for 703 ACTN. A number of key ACTN interfaces exist for deployment and 704 operation of ACTN-based networks. These are highlighted in Figure 5 705 (ACTN Interfaces) below: 707 .-------------- 708 ------------- | 709 | Application |-- 710 ------------- 711 ^ 712 | I/F A -------- 713 v ( ) 714 -------------- - - 715 | Customer | ( Customer ) 716 | Network |--------->( Network ) 717 | Controller | ( ) 718 -------------- - - 719 ^ ( ) 720 | I/F B -------- 721 v 722 -------------- 723 | MultiDomain | 724 | Service | 725 | Coordinator| -------- 726 -------------- ( ) 727 ^ - - 728 | I/F C ( Physical ) 729 v ( Network ) 730 --------------- ( ) -------- 731 | |<----> - - ( ) 732 -------------- | ( ) - - 733 | Physical |-- -------- ( Physical ) 734 | Network |<---------------------->( Network ) 735 | Controller | I/F D ( ) 736 -------------- - - 737 ( ) 738 -------- 740 Figure 7 : ACTN Interfaces 742 The interfaces and functions are described below: 744 . Interface A: A north-bound interface (NBI) that will 745 communicate the service request or application demand. A 746 request will include specific service properties, including: 747 services, topology, bandwidth and constraint information. 749 . Interface B: The CNC-MDSC Interface (CMI) is an interface 750 between a Customer Network Controller and a Multi Service 751 Domain Controller. It requests the creation of the network 752 resources, topology or services for the applications. The 753 Virtual Network Controller may also report potential network 754 topology availability if queried for current capability from 755 the Customer Network Controller. 757 . Interface C: The MDSC-PNC Interface (MPI) is an interface 758 between a Multi Domain Service Coordinator and a Physical 759 Network Controller. It communicates the creation request, if 760 required, of new connectivity of bandwidth changes in the 761 physical network, via the PNC. In multi-domain environments, 762 the MDSC needs to establish multiple MPIs, one for each PNC, as 763 there are multiple PNCs responsible for its domain control. 765 . Interface D: The provisioning interface for creating forwarding 766 state in the physical network, requested via the Physical 767 Network Controller. 769 The interfaces within the ACTN scope are B and C. 771 4. VN creation process 773 The provider can present to the customer different level of network 774 abstraction, spanning from one extreme (say "black") where nothing 775 is shown, just the APs, to the other extreme (say "white") where a 776 slice of the network is shown to the customer. There are shades of 777 gray in between where a number of abstract links and nodes can be 778 shown. 780 The VN creation is composed by two phases: Negotiation and 781 Implementation. 783 Negotiation: In the case of grey/white topology abstraction, there 784 is an a priori phase in which the customer agrees with the provider 785 on the type of topology to be shown, e.q. 10 virtual links and 5 786 virtual nodes with a given interconnectivity. This is something that 787 is assumed to be preconfigured by the operator off-line, what is 788 online is the capability of modifying/deleting something (e.g. a 789 virtual link). In the case of "black" abstraction this negotiation 790 phase does not happen, in the sense that the customer can only see 791 the APs of the network. 793 Implementation: In the case of black topology abstraction, the 794 customers can ask for connectivity with given constraints/SLA 795 between the APs and LSPs/tunnels are created by the provider to 796 satisfy the request. What the customer sees is only that his CEs are 797 connected with a given SLA. In the case of grey/white topology the 798 customer creates his own LSPs accordingly to the topology that was 799 presented to him. 801 5. Access Points and Virtual Network Access Points 803 In order not to share unwanted topological information between the 804 customer domain and provider domain, a new entity is defined and 805 associated to an access link, the Access Point (AP). See the 806 definition of AP in Section 1.1. 808 A customer node will use APs as the end points for the request of 809 VNs. 811 A number of parameters need to be associated to the APs. Such 812 parameters need to include at least: the maximum reservable 813 bandwidth on the link, the available bandwidth and the link 814 characteristics (e.g. switching capability, type of mapping). 816 Editor note: it is not appropriate to define link characteristics 817 like bandwidth against a point (AP). A solution needs to be found. 819 ------------- 820 ( ) 821 - - 822 +---+ X ( ) Z +---+ 823 |CE1|---+----( )---+---|CE2| 824 +---+ | ( ) | +---+ 825 AP1 - - AP2 826 ( ) 827 ------------- 829 Figure 8 : APs definition customer view 831 Let's take as example a scenario in which CE1 is connected to the 832 network via a 10Gb link and CE2 via a 40Gb link. Before the creation 833 of any VN between AP1 and AP2 the customer view can be summarized as 834 follows: 836 +-----+----------+-------------+----------+ 837 |AP id| MaxResBw | AvailableBw | CE,port | 838 +-----+----------+-------------+----------+ 839 | AP1 | 10Gb | 10Gb |CE1,portX | 840 +-----+----------+-------------+----------+ 841 | AP2 | 40Gb | 40Gb |CE2,portZ | 842 +-----+----------+-------------+----------+ 844 Table 1: AP - customer view 846 On the other side what the provider sees is: 848 ------- ------- 849 ( ) ( ) 850 - - - - 851 W (+---+ ) ( +---+) Y 852 -+---( |PE1| Dom.X )----( Dom.Y |PE2| )---+- 853 | (+---+ ) ( +---+) | 854 AP1 - - - - AP2 855 ( ) ( ) 856 ------- ------- 858 Figure 9 : Provider view of the AP 860 Which in the example above ends up in a summarization as follows: 862 +-----+----------+-------------+----------+ 863 |AP id| MaxResBw | AvailableBw | PE,port | 864 +-----+----------+-------------+----------+ 865 | AP1 | 10Gb | 10Gb |PE1,portW | 866 +-----+----------+-------------+----------+ 867 | AP2 | 40Gb | 40Gb |PE2,portY | 868 +-----+----------+-------------+----------+ 870 Table 2: AP - provider view 872 The second entity that needs to be defined is a structure within the 873 AP that is linked to a VN and that is used to allow for different VN 874 to be provided starting from the same AP. It also allows reserving 875 the bandwidth for the VN on the access link. Such entity is called 876 Virtual Network Access Point. For each virtual network is defined on 877 an AP, a different VNAP is created. 879 In the simple scenario depicted above we suppose to create two 880 virtual networks. The first one has with VN identifier 9 between AP1 881 and AP2 with and bandwidth of 1Gbps, while the second one with VN id 882 5, again between AP1 and AP2 and bandwidth 2Gbps. 884 The customer view would evolve as follows: 886 +---------+----------+-------------+----------+ 887 |AP/VNAPid| MaxResBw | AvailableBw | PE,port | 888 +---------+----------+-------------+----------+ 889 |AP1 | 10Gbps | 7Gbps |PE1,portW | 890 | -VNAP1.9| 1Gbps | N.A. | | 891 | -VNAP1.5| 2Gbps | N.A | | 892 +---------+----------+-------------+----------+ 893 |AP2 | 40Gb | 37Gb |PE2,portY | 894 | -VNAP2.9| 1Gbps | N.A. | | 895 | -VNAP2.5| 2Gbps | N.A | | 896 +---------+----------+-------------+----------+ 898 Table 3: AP and VNAP - provider view after VN creation 900 5.1. Dual homing scenario 902 Often there is a dual homing relationship between a CE and a pair of 903 PE. This case needs to be supported also by the definition of VN, AP 904 and VNAP. Suppose to have CE1 connected to two different PE in the 905 operator domain via AP1 and AP2 and the customer needing 5Gbps of 906 bandwidth between CE1 and CE2. 908 AP1 -------------- AP3 909 -------(PE1) (PE3) ------- 910 W / - - \X 911 +---+ / ( ) \ +---+ 912 |CE1| ( ) |CE2| 913 +---+ \ ( ) / +---+ 914 Y \ - - /Z 915 -------(PE2) (PE4) ------- 916 AP2 -------------- AP4 918 Figure 10 : Dual homing scenario 920 In this case the customer will request for a VN between AP1, AP2 and 921 AP3 specifying a dual homing relationship between AP1 and AP2. As a 922 consequence no traffic will be flowing between AP1 and AP2. The dual 923 homing relationship would then be mapped against the VNAPs (since 924 other independent VNs might have AP1 and AP2 as end points). 926 The customer view would be as follows: 928 +---------+----------+-------------+----------+-----------+ 929 |AP/VNAPid| MaxResBw | AvailableBw | CE,port |Dual Homing| 930 +---------+----------+-------------+----------+-----------+ 931 |AP1 | 10Gbps | 5Gbps |CE1,portW | | 932 | -VNAP1.9| 5Gbps | N.A. | | VNAP2.9 | 933 +---------+----------+-------------+----------+-----------+ 934 |AP2 | 40Gbps | 35Gbps |CE1,portY | | 935 | -VNAP2.9| 5Gbps | N.A. | | VNAP1.9 | 936 +---------+----------+-------------+----------+-----------+ 937 |AP3 | 40Gbps | 35Gbps |CE2,portZ | | 938 | -VNAP3.9| 5Gbps | N.A. | | NONE | 939 +---------+----------+-------------+----------+-----------+ 941 Table 4: Dual homing - customer view after VN creation 943 6. End point selection & mobility 945 Virtual networks could be used as the infrastructure to connect a 946 number of sites of a customer among them or to provide connectivity 947 between customer sites and virtualized network functions (VNF) like 948 for example virtualized firewall, vBNG, storage, computational 949 functions. 951 6.1. End point selection & mobility 953 A VNF could be deployed in different places (e.g. data centers A, B 954 or C in figure below) but the VNF provider (=ACTN customer) doesn't 955 know which is the best site where to install the VNF from a network 956 point of view (e.g. latency). For example it is possible to compute 957 the path minimizing the delay between AP1 and AP2, but the customer 958 doesn't know a priori if the path with minimum delay is towards A, B 959 or C. 961 ------- ------- 962 ( ) ( ) 963 - - - - 964 +---+ ( ) ( ) +----+ 965 |CE1|---+----( Domain X )----( Domain Y )---+---|DC-A| 966 +---+ | ( ) ( ) | +----+ 967 AP1 - - - - AP2 968 ( ) ( ) 969 ---+--- ---+--- 970 AP3 | AP4 | 971 +----+ +----+ 972 |DC-B| |DC-C| 973 +----+ +----+ 975 Figure 11 : End point selection 977 In this case the VNF provider (=ACTN customer) should be allowed to 978 ask for a VN between AP1 and a set of end points. The list of end 979 points is provided by the VNF provider. When the end point is 980 identified the connectivity can be instantiated and a notification 981 can be sent to the VNF provider for the instantiation of the VNF. 983 6.2. Preplanned end point migration 985 A premium SLA for VNF service provisioning consists on the offering 986 of a protected VNF instantiated on two or more sites and with a hot 987 stand-by protection mechanism. In this case the VN should be 988 provided so to switch from one end point to another upon a trigger 989 from the VNF provider or an automatic failure detection mechanism. 990 An example is provided in figure below where the request from the 991 VNF provider is for connectivity with given constraint and 992 resiliency between CE1 and a VNF with primary installation in DC-A 993 and a protection in DC-C. 995 ------- ------- 996 ( ) ( ) 997 - - __ - - 998 +---+ ( ) ( ) +----+ 999 |CE1|---+----( Domain X )----( Domain Y )---+---|DC-A| 1000 +---+ | ( ) ( ) | +----+ 1001 AP1 - - - - AP2 | 1002 ( ) ( ) | 1003 ---+--- ---+--- | 1004 AP3 | AP4 | HOT STANDBY 1005 +----+ | 1006 |DC-C|<------------- 1007 +----+ 1009 Figure 12 : Preplanned endpoint migration 1011 6.3. On the fly end point migration 1013 The one the fly end point migration concept is very similar to the 1014 end point selection one. The idea is to give the provider not only 1015 the list of sites where the VNF can be installed, but also a 1016 mechanism to notify changes in the network that have impacts on the 1017 SLA. After an handshake with the customer controller/applications, 1018 the bandwidth in network would be moved accordingly with the moving 1019 of the VNFs. 1021 7. Security 1023 TBD 1025 8. References 1027 8.1. Informative References 1029 [PCE] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path 1030 Computation Element (PCE)-Based Architecture", IETF RFC 1031 4655, August 2006. 1033 [RFC4026] L. Andersson, T. Madsen, "Provider Provisioned Virtual 1034 Private Network (VPN) Terminology", RFC 4026, March 2005. 1036 [RFC4208] G. Swallow, J. Drake, H.Ishimatsu, Y. Rekhter, 1037 "Generalized Multiprotocol Label Switching (GMPLS) User- 1038 Network Interface (UNI): Resource ReserVation Protocol- 1039 Traffic Engineering (RSVP-TE) Support for the Overlay 1040 Model", RFC 4208, October 2005. 1042 [RFC7926] A. Farrel (Ed.), "Problem Statement and Architecture for 1043 Information Exchange between Interconnected Traffic- 1044 Engineered Networks", RFC 7926, July 2016. 1046 [PCE-S] Crabbe, E, et. al., "PCEP extension for stateful 1047 PCE",draft-ietf-pce-stateful-pce, work in progress. 1049 [GMPLS] Manning, E., et al., "Generalized Multi-Protocol Label 1050 Switching (GMPLS) Architecture", RFC 3945, October 2004. 1052 [NFV-AF] "Network Functions Virtualization (NFV); Architectural 1053 Framework", ETSI GS NFV 002 v1.1.1, October 2013. 1055 [ACTN-PS] Y. Lee, D. King, M. Boucadair, R. Jing, L. Contreras 1056 Murillo, "Problem Statement for Abstraction and Control of 1057 Transport Networks", draft-leeking-actn-problem-statement, 1058 work in progress. 1060 [ONF] Open Networking Foundation, "OpenFlow Switch Specification 1061 Version 1.4.0 (Wire Protocol 0x05)", October 2013. 1063 [TE-INFO] A. Farrel, Editor, "Problem Statement and Architecture for 1064 Information Exchange Between Interconnected Traffic 1065 Engineered Networks", draft-ietf-teas-interconnected-te- 1066 info-exchange, work in progress. 1068 [ABNO] King, D., and Farrel, A., "A PCE-based Architecture for 1069 Application-based Network Operations", draft-farrkingel- 1070 pce-abno-architecture, work in progress. 1072 [ACTN-Info] Y. Lee, S. Belotti, D. Dhody, "Information Model for 1073 Abstraction and Control of Transport Networks", draft- 1074 leebelotti-teas-actn-info, work in progress. 1076 [Cheng] W. Cheng, et. al., "ACTN Use-cases for Packet Transport 1077 Networks in Mobile Backhaul Networks", draft-cheng-actn- 1078 ptn-requirements, work in progress. 1080 [Dhody] D. Dhody, et. al., "Packet Optical Integration (POI) Use 1081 Cases for Abstraction and Control of Transport Networks 1082 (ACTN)", draft-dhody-actn-poi-use-case, work in progress. 1084 [Fang] L. Fang, "ACTN Use Case for Multi-domain Data Center 1085 Interconnect", draft-fang-actn-multidomain-dci, work in 1086 progress. 1088 [Klee] K. Lee, H. Lee, R. Vilata, V. Lopez, "ACTN Use-case for On- 1089 demand E2E Connectivity Services in Multiple Vendor Domain 1090 Transport Networks", draft-klee-actn-connectivity-multi- 1091 vendor-domains, work in progress. 1093 [Kumaki] K. Kumaki, T. Miyasaka, "ACTN : Use case for Multi Tenant 1094 VNO ", draft-kumaki-actn-multitenant-vno, work in 1095 progress. 1097 [Lopez] D. Lopez (Ed), "ACTN Use-case for Virtual Network Operation 1098 for Multiple Domains in a Single Operator Network", draft- 1099 lopez-actn-vno-multidomains, work in progress. 1101 [Shin] J. Shin, R. Hwang, J. Lee, "ACTN Use-case for Mobile Virtual 1102 Network Operation for Multiple Domains in a Single 1103 Operator Network", draft-shin-actn-mvno-multi-domain, work 1104 in progress. 1106 [Xu] Y. Xu, et. al., "Use Cases and Requirements of Dynamic Service 1107 Control based on Performance Monitoring in ACTN 1108 Architecture", draft-xu-actn-perf-dynamic-service-control, 1109 work in progress. 1111 9. Contributors 1113 Authors' Addresses 1115 Daniele Ceccarelli (Editor) 1116 Ericsson 1117 Torshamnsgatan,48 1118 Stockholm, Sweden 1119 Email: daniele.ceccarelli@ericsson.com 1121 Young Lee (Editor) 1122 Huawei Technologies 1123 5340 Legacy Drive 1124 Plano, TX 75023, USA 1125 Phone: (469)277-5838 1126 Email: leeyoung@huawei.com 1128 Luyuan Fang 1129 Email: luyuanf@gmail.com 1131 Diego Lopez 1132 Telefonica I+D 1133 Don Ramon de la Cruz, 82 1134 28006 Madrid, Spain 1135 Email: diego@tid.es 1137 Sergio Belotti 1138 Alcatel Lucent 1139 Via Trento, 30 1140 Vimercate, Italy 1141 Email: sergio.belotti@alcatel-lucent.com 1143 Daniel King 1144 Lancaster University 1145 Email: d.king@lancaster.ac.uk 1147 Dhruv Dhoddy 1148 Huawei Technologies 1149 dhruv.ietf@gmail.com 1151 Gert Grammel 1152 Juniper Networks 1153 ggrammel@juniper.net