NFV RG CJ. Bernardos Internet-Draft UC3M Intended status: Informational LM. Contreras Expires: March 14, 2018 TID I. Vaishnavi Huawei R. Szabo Ericsson September 10, 2017 Multi-domain Network Virtualization draft-bernardos-nfvrg-multidomain-03 Abstract This draft analyzes the problem of multi-provider multi-domain orchestration, by first scoping the problem, then looking into potential architectural approaches, and finally describing the solutions being developed by the European 5GEx project. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on March 14, 2018. Copyright Notice Copyright (c) 2017 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect Bernardos, et al. Expires March 14, 2018 [Page 1] Internet-Draft Multi-domain Network Virtualization September 2017 to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Background: the ETSI NFV architecture . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Multidomain problem statement . . . . . . . . . . . . . . . . 6 5. Multi-domain architectural approaches . . . . . . . . . . . . 7 5.1. ETSI NFV approaches . . . . . . . . . . . . . . . . . . . 8 5.2. Hierarchical . . . . . . . . . . . . . . . . . . . . . . 11 5.3. Cascading . . . . . . . . . . . . . . . . . . . . . . . . 13 6. Virtualization and Control for Multi-Provider Multi-Domain . . . . . . . . . . . . . . . . . 13 6.1. Interworking interfaces . . . . . . . . . . . . . . . . . 15 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 8. Security Considerations . . . . . . . . . . . . . . . . . . . 16 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 16 10. Informative References . . . . . . . . . . . . . . . . . . . 16 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 1. Introduction The telecommunications sector is experiencing a major revolution that will shape the way networks and services are designed and deployed for the next decade. We are witnessing an explosion in the number of applications and services demanded by users, which are now really capable of accessing them on the move. In order to cope with such a demand, some network operators are looking at the cloud computing paradigm, which enables a potential reduction of the overall costs by outsourcing communication services from specific hardware in the operator's core to server farms scattered in datacenters. These services have different characteristics if compared with conventional IT services that have to be taken into account in this cloudification process. Also the transport network is affected in that it is evolving to a more sophisticated form of IP architecture with trends like separation of control and data plane traffic, and more fine- grained forwarding of packets (beyond looking at the destination IP address) in the network to fulfill new business and service goals. Virtualization of functions also provides operators with tools to deploy new services much faster, as compared to the traditional use of monolithic and tightly integrated dedicated machinery. As a natural next step, mobile network operators need to re-think how to Bernardos, et al. Expires March 14, 2018 [Page 2] Internet-Draft Multi-domain Network Virtualization September 2017 evolve their existing network infrastructures and how to deploy new ones to address the challenges posed by the increasing customers' demands, as well as by the huge competition among operators. All these changes are triggering the need for a modification in the way operators and infrastructure providers operate their networks, as they need to significantly reduce the costs incurred in deploying a new service and operating it. Some of the mechanisms that are being considered and already adopted by operators include: sharing of network infrastructure to reduce costs, virtualization of core servers running in data centers as a way of supporting their load- aware elastic dimensioning, and dynamic energy policies to reduce the monthly electricity bill. However, this has proved to be tough to put in practice, and not enough. Indeed, it is not easy to deploy new mechanisms in a running operational network due to the high dependency on proprietary (and sometime obscure) protocols and interfaces, which are complex to manage and often require configuring multiple devices in a decentralized way. Network Function Virtualization (NFV) and Software Defined Networking (SDN) are changing the way the telecommunications sector will deploy, extend and operate their networks. TBD: add multi-domain. 2. Terminology The following terms used in this document are defined by the ETSI NVF ISG, and the ONF and the IETF: NFV Infrastructure (NFVI): totality of all hardware and software components which build up the environment in which VNFs are deployed NFV Management and Orchestration (NFV-MANO): functions collectively provided by NFVO, VNFM, and VIM. NFV Orchestrator (NFVO): functional block that manages the Network Service (NS) lifecycle and coordinates the management of NS lifecycle, VNF lifecycle (supported by the VNFM) and NFVI resources (supported by the VIM) to ensure an optimized allocation of the necessary resources and connectivity. Network Service Orchestration (NSO): function responsible for the Network Service lifecycle management, including operations such as: On-board Network Service, Instantiate Network Service, Scale Network Service, Update Network Service, etc. OpenFlow protocol (OFP): allowing vendor independent programming of control functions in network nodes. Bernardos, et al. Expires March 14, 2018 [Page 3] Internet-Draft Multi-domain Network Virtualization September 2017 Resource Orchestration (RO): subset of NFV Orchestrator functions that are responsible for global resource management governance. Service Function Chain (SFC): for a given service, the abstracted view of the required service functions and the order in which they are to be applied. This is somehow equivalent to the Network Function Forwarding Graph (NF-FG) at ETSI. Service Function Path (SFP): the selection of specific service function instances on specific network nodes to form a service graph through which an SFC is instantiated. Virtualized Infrastructure Manager (VIM): functional block that is responsible for controlling and managing the NFVI compute, storage and network resources, usually within one operator's Infrastructure Domain. Virtualized Network Function (VNF): implementation of a Network Function that can be deployed on a Network Function Virtualization Infrastructure (NFVI). Virtualized Network Function Manager (VNFM): functional block that is responsible for the lifecycle management of VNF. 3. Background: the ETSI NFV architecture The ETSI ISG NFV is a working group which, since 2012, aims to evolve quasi-standard IT virtualization technology to consolidate many network equipment types into industry standard high volume servers, switches, and storage. It enables implementing network functions in software that can run on a range of industry standard server hardware and can be moved to, or loaded in, various locations in the network as required, without the need to install new equipment. To date, ETSI NFV is by far the most accepted NFV reference framework and architectural footprint [etsi_nvf_whitepaper]. The ETSI NFV framework architecture framework is composed of three domains (Figure 1): o Virtualized Network Function, running over the NFVI. o NFV Infrastructure (NFVI), including the diversity of physical resources and how these can be virtualized. NFVI supports the execution of the VNFs. o NFV Management and Orchestration, which covers the orchestration and life-cycle management of physical and/or software resources that support the infrastructure virtualization, and the life-cycle management of VNFs. NFV Management and Orchestration focuses on Bernardos, et al. Expires March 14, 2018 [Page 4] Internet-Draft Multi-domain Network Virtualization September 2017 all virtualization specific management tasks necessary in the NFV framework. +-------------------------------------------+ +---------------+ | Virtualized Network Functions (VNFs) | | | | ------- ------- ------- ------- | | | | | | | | | | | | | | | | | VNF | | VNF | | VNF | | VNF | | | | | | | | | | | | | | | | | ------- ------- ------- ------- | | | +-------------------------------------------+ | | | | +-------------------------------------------+ | | | NFV Infrastructure (NFVI) | | NFV | | ----------- ----------- ----------- | | Management | | | Virtual | | Virtual | | Virtual | | | and | | | Compute | | Storage | | Network | | | Orchestration | | ----------- ----------- ----------- | | | | +---------------------------------------+ | | | | | Virtualization Layer | | | | | +---------------------------------------+ | | | | +---------------------------------------+ | | | | | ----------- ----------- ----------- | | | | | | | Compute | | Storage | | Network | | | | | | | ----------- ----------- ----------- | | | | | | Hardware resources | | | | | +---------------------------------------+ | | | +-------------------------------------------+ +---------------+ Figure 1: ETSI NFV framework The NFV architectural framework identifies functional blocks and the main reference points between such blocks. Some of these are already present in current deployments, whilst others might be necessary additions in order to support the virtualization process and consequent operation. The functional blocks are (Figure 2): o Virtualized Network Function (VNF). o Element Management (EM). o NFV Infrastructure, including: Hardware and virtualized resources, and Virtualization Layer. o Virtualized Infrastructure Manager(s) (VIM). o NFV Orchestrator. Bernardos, et al. Expires March 14, 2018 [Page 5] Internet-Draft Multi-domain Network Virtualization September 2017 o VNF Manager(s). o Service, VNF and Infrastructure Description. o Operations and Business Support Systems (OSS/BSS). +--------------------+ +-------------------------------------------+ | ---------------- | | OSS/BSS | | | NFV | | +-------------------------------------------+ | | Orchestrator +-- | | ---+------------ | | +-------------------------------------------+ | | | | | --------- --------- --------- | | | | | | | EM 1 | | EM 2 | | EM 3 | | | | | | | ----+---- ----+---- ----+---- | | ---+---------- | | | | | | |--|-| VNF | | | | ----+---- ----+---- ----+---- | | | manager(s) | | | | | VNF 1 | | VNF 2 | | VNF 3 | | | ---+---------- | | | ----+---- ----+---- ----+---- | | | | | +------|-------------|-------------|--------+ | | | | | | | | | | | +------+-------------+-------------+--------+ | | | | | NFV Infrastructure (NFVI) | | | | | | ----------- ----------- ----------- | | | | | | | Virtual | | Virtual | | Virtual | | | | | | | | Compute | | Storage | | Network | | | | | | | ----------- ----------- ----------- | | ---+------ | | | +---------------------------------------+ | | | | | | | | Virtualization Layer | |--|-| VIM(s) +-------- | | +---------------------------------------+ | | | | | | +---------------------------------------+ | | ---------- | | | ----------- ----------- ----------- | | | | | | | Compute | | Storage | | Network | | | | | | | | hardware| | hardware| | hardware| | | | | | | ----------- ----------- ----------- | | | | | | Hardware resources | | | NFV Management | | +---------------------------------------+ | | and Orchestration | +-------------------------------------------+ +--------------------+ Figure 2: ETSI NFV reference architecture 4. Multidomain problem statement Market fragmentation results from having a multitude of telecommunications network and cloud operators each with a footprint focused to a specific region. This makes it difficult to deploy cost effective infrastructure services, such as virtual connectivity or compute resources, spanning multiple countries as no single operator Bernardos, et al. Expires March 14, 2018 [Page 6] Internet-Draft Multi-domain Network Virtualization September 2017 has a big enough footprint. Even if operators largely aim to provide the same infrastructure services (VPN connectivity, compute resources based on virtual machines and block storage), inter-operator collaboration tools for providing a service spanning several administrative boundaries are very limited and cumbersome. This makes service development and provisioning very time consuming. For example, having a VPN with end-points in several countries, in order to connect multiple sites of a business (such as a hotel chain), requires contacting several network operators. Such an approach is possible only with significant effort and integration work from the side of the business. This is not only slow, but also inefficient and expensive, since the business also needs to employ networking specialists to do the integration instead of focusing on its core business Technology fragmentation also represents a major bottleneck internally for an operator. Different networks and different parts of a network may be built as different domains using separate technologies, such as optical or packet switched (with different packet switching paradigms included); having equipment from different vendors; having different control paradigms, etc. Managing and integrating these separate technology domains requires substantial amount of effort, expertise, and time. The associated costs are paid by both network operators and vendors alike, who need to design equipment and develop complex integration features. In addition to technology domains, there are other reasons for having multiple domains within an operator, such as, different geographies, different performance characteristics, scalability, policy or simply historic (e.g., result of a merge or an acquisition). Multiple domains in a network are a necessary and permanent feature however, these should not be a roadblock towards service development and provisioning, which should be fast and efficient. A solution is needed to deal with both the multi-operator collaboration issue, and address the multi-domain problem within a single network operator. While these two problems are quite different, they also share a lot of common aspects and can benefit from having a number of common tools to solve them. 5. Multi-domain architectural approaches This section summarizes different architectural options that can be considered to tackle the multi-domain orchestration problem. Bernardos, et al. Expires March 14, 2018 [Page 7] Internet-Draft Multi-domain Network Virtualization September 2017 5.1. ETSI NFV approaches Recently, the ETSI NFV ISG has started to look into viable architectural options supporting the placement of functions in different administrative domains. In the document [etsi_nvf_ifa009], different approaches are considered, which we summarize next. The first option (shown in Figure 3) is based on a split of the NFVO into Network Service Orchestrator (NSO) and Resource Orchestrator (RO). A use case that this separation could enable is the following: a network operator offering its infrastructure to different departments within the same operator, as well as to a different network operator like in cases of network sharing agreements. In this scenario, an administrative domain can be defined as one or more data centers and VIMs, providing an abstracted view of the resources hosted in it. A service is orchestrated out of VNFs that can run on infrastructure provided and managed by another Service Provider. The NSO manages the lifecycle of network services, while the RO provides an overall view of the resources present in the administrative domain to which it provides access and hides the interfaces of the VIMs present below it. Bernardos, et al. Expires March 14, 2018 [Page 8] Internet-Draft Multi-domain Network Virtualization September 2017 ------- | NSO | /-------\ / \ -------- / -------- \ -------- | VNFM | | | VNFM | | | VNFM | -------- / -------- \ -------- / ____/ / \ \____ \ / / _________/ \_________ \ \ / / / \ \ \ +-----------/-/-/---------+ +----------\-\-\----------+ | --------- | | --------- | | | RO | | | | RO | | | --------- | | --------- | | / | \ | | / | \ | | / | \ | | / | \ | | / | \ | | / | \ | | ------- ------- ------- | | ------- ------- ------- | | |VIM 1| |VIM 2| |VIM 3| | | |VIM 1| |VIM 2| |VIM 3| | | ------- ------- ------- | | ------- ------- ------- | | Administrative domain A | | Administrative domain B | +-------------------------+ +-------------------------+ Figure 3: Infrastructure provided using multiple administrative domains (from ETSI GS NFV-IFA 009 V1.1.1) The second option (shown in Figure 4) is based on having an umbrella NFVO. A use case enabled by this is the following: a Network Operator offers Network Services to different departments within the same operator, as well as to a different network operator like in cases of network sharing agreements. In this scenario, an administrative domain is compose of one or more Datacentres, VIMs, VNFMs (together with their related VNFs) and NFVO, allowing distinct specific sets of network services to be hosted and offered on each. A top Network Service can include another Network Service. A Network Service containing other Network Services might also contain VNFs. The NFVO in each admin domain provides visibility of the Network Services specific to this admin domain. The umbrella NFVO is providing the lifecycle management of umbrella network services defined in this NFVO. In each admin domain, the NFVO is providing standard NFVO functionalities, with a scope limited to the network services, VNFs and resources that are part of its admin domain. Bernardos, et al. Expires March 14, 2018 [Page 9] Internet-Draft Multi-domain Network Virtualization September 2017 ------------ | Umbrella | | NFVO | ------------ / | \ / | \ / -------- \ / | VNFM | \ / -------- \ / | \ / ------- \ / |VIM 1| \ / ------- \ --------------/------------ -------------\------------- | -------- | | -------- | | | NFVO | | | | NFVO | | | -------- | | -------- | | | | | | | | | | | | -------- | | | -------- | | -------- | | | -------- | | | VNFM | | | | | VNFM | | | | VNFM | | | | | VNFM | | | -------- | | | -------- | | -------- | | | -------- | | | \__/__|__\_/_ | | | | \__/__|__\_/_ | | | | __/___|___/\ \ | | | | __/___|___/\ \ | | | | / / | \ \ | | | | / / | \ \ | | | ------- ------- ------- | | ------- ------- ------- | | |VIM 1| |VIM 2| |VIM 3| | | |VIM 1| |VIM 2| |VIM 3| | | ------- ------- ------- | | ------- ------- ------- | | Administrative domain A | | Administrative domain B | +-------------------------+ +-------------------------+ Figure 4: Network services provided using multiple administrative domains (from ETSI GS NFV-IFA 009 V1.1.1) More recently, ETSI NFV has released a new whitepaper, titled "Network Operator Perspectives on NFV priorities for 5G" [etsi_nvf_whitepaper_5g], which provides network operator perspectives on NFV priorities for 5G and identifies common technical features in terms of NFV. This whitepaper identifies multi-site/ multi-tenant orchestration as one key priority. ETSI highlights the support of Infrastructure as a Service (IaaS), NFV as a Service (NFVaaS) and Network Service (NS) composition in different administrative domains (for example roaming scenarios in wireless networks) as critical for the 5G work. Related to this, a new Work Item, IFA028, and titled as "Report on architecture options to support multiple administrative domains" has been approved. Bernardos, et al. Expires March 14, 2018 [Page 10] Internet-Draft Multi-domain Network Virtualization September 2017 5.2. Hierarchical Considering the potential split of the NFVO into a Network Service Orchestrator (NSO) and a Resource Orchestrator (RO), multi-provider hierarchical interfaces may exist at their northbound APIs. Figure 5 illustrates the various interconnection options, namely: E/NSO (External NSO): an evolved NFVO northbound API based on Network Service (NS). E/RO (External RO): VNF-FG oriented resource embedding service. A received VNF-FG that is mapped to the northbound resource view is embedded into the distributed resources collected from southbound, i.e., VNF-FG_in = VNF-FG_out_1 + VNF-FG_out_2 + ... + VNF- FG_out_N, where VNF-FG_out_j corresponds to a spatial embedding to subordinate domain "j". For example, Provider 3's MP-NFVO/RO creates VNF-FG corresponding to its E/RO and E/VIM sub-domains. E/VIM (External VIM): a generic VIM interface offered to an external consumer. In this case the NFVI-PoP may be shared for multiple consumers, each seeing a dedicated NFVI-PoP. This corresponds to IaaS interface. I/NSO (Internal NSO): if a Multi-provider NSO (MP-NSO) is separated from the provider's operational NSO, e.g., due to different operational policies, the MP-NSO may need this interface to realize its northbound E/NSO requests. Provider 1 illustrates a scenario the MP-NSO and the NSO are logically separated. Observe that Provider 1's tenants connect to the NSO and MP-NSO corresponds to "wholesale" services. I/RO (Internal RO): VNF-FG oriented resource embedding service. A received VNF-FG that is mapped to the northbound resource view is embedded into the distributed resources collected from southbound, i.e., VNF-FG_in = VNF-FG_out_1 + VNF-FG_out_2 + ... + VNF- FG_out_N, where VNF-FG_out_j corresponds to a spatial embedding to subordinate domain "j". For example, Provider 1's MP-NFVO/RO creates VNF-FG corresponding to its I/RO and I/VIM sub-domains. I/VIM (Internal VIM): a generic VIM interface at an NFVI-PoP. Nfvo-Vim: a generic VIM interface between a (monolithic) NFVO and a VIM. We would like to explore use-cases and potential benefits for the above multi-provider interfaces as well as to learn how much they may differ from their existing counterparts. For example, are (E/RO, I/ RO), (E/NSO, I/NSO), (E/VIM, I/VIM) pairs different? Bernardos, et al. Expires March 14, 2018 [Page 11] Internet-Draft Multi-domain Network Virtualization September 2017 Tenants * Provider | * * Domain 4 +--+-----------+ * * |MP-NFVO/NSO: | * * |Network Serv. | * Provider * |Orchestrator | * Domain 3 * +--+-----------+ * Tenants * |E/RO * | ************|************* * ++-------------+ | * |MP-NFVO/NSO: | | Provider * |Network Serv. | | Domain 1 * |Orchestrator | | * +-+-----+------+ | * E/NSO| | I/RO / *.---------' +-+---------+--+ /* |MP-NFVO/RO: | / * |Rersource | Tenants / * |Orchestrator | | | * +--+---+-------+ | +-----------+--+ *************|***|******************** | |MP-NFVO/NSO: | | * \ Provider | |Network Serv. | E/RO / * \ E/VIM Domain 2 | |Orchestrator | .-----------' * `-------. | +-+------+-----+ | * | | |I/NSO |I/RO | * | | | +--+--------+--+ * | | | |MP-NFVO/RO: | * | | | |Rersource | * | \ | |Orchestrator | * +------+-------+ \ | +----+---- --+-+ * |VIM: | +--+-----+ |I/RO |I/VIM * |Virtualized | |NFVO/NSO| | | * |Pys mapping | +------+-+ | | * +--------------+ I/RO| | | * +------+----+---+ | * | NFVO/RO | | * ++-------------++ | * |Nfvo-Vim | | * ++-------+ ++----+--+ * |WIM|VIM || |VIM|WIM | * +--------+| +--------+ * +--------+ * Figure 5: NSO-RO Split: possible multi-provider APIs - an illustration Bernardos, et al. Expires March 14, 2018 [Page 12] Internet-Draft Multi-domain Network Virtualization September 2017 5.3. Cascading Cascading is an alternative way of relationship among providers, from the network service point of view. In this case, service decomposition is implemented in a paired basis. This can be extended in a recursive manner, then allowing for a concatenation of cascaded relations between providers. As a complement to this, from a service perspective, the cascading of two remote providers (i.e., providers not directly interconnected) could require the participation of a third provider (or more) facilitating the necessary communication among the other two. In that sense, the final service involves two providers while the connectivity imposes the participation of more parties at resource level. 6. Virtualization and Control for Multi-Provider Multi-Domain Orchestration operation in multi-domain is somewhat different from that in a single domain as the assumption in single domain single provider orchestration is that the orchestrator is aware of the entire topology and resource availability within its domain as well as has complete control over those resources. This assumption of technical control cannot be made in a multi domain scenario, furthermore the assumption of the knowledge of the resources and topologies cannot be made across providers. In such a scenario solutions are required that enable the exchange of relevant information across these orchestrators. This exchange needs to be standardized as shown in Figure 6. | | + IF1 + _____|____ ____|_____ | Multi | IF2 | Multi | | Provider |<--------+---------->| Provider | |___Orch___| |___Orch___| /\ /\ / \ / \ / \ IF3 / \ _______/__ _\_________ ________/_ _\________ | Domain | | Domain | | Domain | | Domain | |___Orch___| |___Orch___| |___Orch___| |___Orch___| Figure 6: Multi Domain Multi Provider reference architecture The figure shows the Multi Provider orchestrator exposing an interface 1 (IF1) to the tenant, interface 2 (IF2) to other Multi Provider Orchestrator (MPO) and an interface 3 (IF3) to individual Bernardos, et al. Expires March 14, 2018 [Page 13] Internet-Draft Multi-domain Network Virtualization September 2017 domain orchestratrators. Each one of these interfaces could be a possible standardization candidate. Interface 1 is exposed to the tennnt who could request his specific services and/or slices to be deployed. Interface 2 is between the orchestrator and is a key interface to enable multi-provider operation. Interface 3 focuses on abstracting the technology or vendor dependent implementation details to support orchestration. The proposed operation of the MPO follows three main technical steps. First, over interface 2 various functions such as abstracted topology discovery, pricing and service details are detected. Second, once a request for deploying a service is received over interface 1 the Multi Provider Orchestrator evaluates the best orchestrators to implement parts of this request. The request to deploy these parts are sent to the different domain orchestrators over IF2 and IF3 and the acknowledgement that these are deployed in different domain are received back over those interfaces. Third, on receipt of the acknowledgement the slice specific assurance management is started within the MPO. This assurance function collects the appropriate information over IF2 and IF3 and reports the performance back to the tenant over IF1. The assurance is also responsible for detecting any failures in the service and violations in the SLA and recomending to the orchestration engine the reconfiguration of the service or slice which again needs to performed over IF2 and IF3. Each of the three steps is assigned to a specific block in our high level architecture shown in Figure 7. | | + IF1 + ______________|______________ ____|_____ | Multi Provider Orch | | Multi | | ______ ________ _______ |<------+------->| Provider | ||Assur-| | | | Catal-|| IF2 |___Orch___| ||-ance | | NFVO | | logue || || Mgmt.| | | | Topo. || ||______| |________| |_Mgmt._|| |_____________________________| /\ / \ IF3 Figure 7: Detailed MPO reference architecture The catalogue and topology management system is responsible for step 1. It discovers the service as well as the resources exposed by the other domains both on IF2 and IF3. The combination of these services with coverage over the detected topology is provided to the user over IF1. In turn the catalogue and topology management system is also Bernardos, et al. Expires March 14, 2018 [Page 14] Internet-Draft Multi-domain Network Virtualization September 2017 responsible for exposing the topology and service deployment capabilities to the other domain. The exposure over interface 2 to other MPO maybe abstracted and the mapping of this abstracted view to the real view when requested byt he NFVO. The NFVO (Network Function Virtualization Orchestrator) is responsible for the second step. It deploys the service or slice as is received from the tenant over IF2 and IF3. It then hands over the deployment decisions to the Assurance managmeent subsystem which use this information to collect the periodic monitoring tickets in step 3. On the other end it is responsible for receiving the request over IF2 to deploy a part of the service, consult with the catalogue and topology management system on the translation of the abstraction to the received request and then for the actual deployment over the domains using IF3. The result of this deployment and the management and control handles to access the deployed slice or service is then returned to the requesting MPO. The assurance management component periodically studies the collected results to report the overall service performance to the tenant or the requesting MPO as well as to ensure that the service is functioning within the specified parameters. In case of failures or violations the Assurance management system recomends reconfigurations to the NFVO. 6.1. Interworking interfaces In this section we provide more details on the interworking interfaces of the MPO reference architecture. Each interface IF1, IF2 and IF3 is broken down into several sub-interfaces. Each of them has a clear scope and functionality. [Ed. note: more details will be added in future releases of this document] For multi provider Network Service orchestration, the Multi-domain Orchestrator (MdO) offers Network Services by exposing an OSS/BSS - NFVO interface to other MPOs belonging to other providers. For multi-provider resource orchestration, the MPO presents a VIM-like view and exposes an extended NFVO - VIM interface to other MPOs. The MPO exposes a northbound sub-interface (IF1-S) through which an MPO customer sends the initial request for services. It handles command and control functions to instantiate network services. Such functions include requesting the instantiation and interconnection of Network Functions (NFs). A sub-interface IF2-S is defined to perform similar operations between MPOs of different administrative domains. A set of sub-interfaces -- IF3-R and IF2-R -- are used to keep an updated global view of the underlying infrastructure topology exposed by domain orchestrators. The service catalogue exposes available services to customers on a sub-interface IF1-C and to other MPO Bernardos, et al. Expires March 14, 2018 [Page 15] Internet-Draft Multi-domain Network Virtualization September 2017 service operators on sub-interface IF2-C. Resource orchestration related interfaces are broken up to IF2-RC, IF2-RT, IF2-RMon to reflect resource control, resource topology and resource monitoring respectively. Furthermore, the sub-interfaces introduced before are generalised and also used for interfaces IF3 and IF1. 7. IANA Considerations N/A. 8. Security Considerations TBD. 9. Acknowledgments This work is supported by 5G-PPP 5GEx, an innovation action project partially funded by the European Community under the H2020 Program (grant agreement no. 671636). The views expressed here are those of the authors only. The European Commission is not liable for any use that may be made of the information in this presentation. 10. Informative References [etsi_nvf_ifa009] "Report on Architectural Options, ETSI GS NFV-IFA 009 V1.1.1", July 2016. [etsi_nvf_whitepaper] "Network Functions Virtualisation (NFV). White Paper 2", October 2014. [etsi_nvf_whitepaper_5g] "Network Functions Virtualisation (NFV). White Paper on "Network Operator Perspectives on NFV priorities for 5G"", February 2017. Authors' Addresses Carlos J. Bernardos Universidad Carlos III de Madrid Av. Universidad, 30 Leganes, Madrid 28911 Spain Phone: +34 91624 6236 Email: cjbc@it.uc3m.es URI: http://www.it.uc3m.es/cjbc/ Bernardos, et al. Expires March 14, 2018 [Page 16] Internet-Draft Multi-domain Network Virtualization September 2017 Luis M. Contreras Telefonica I+D Ronda de la Comunicacion, S/N Madrid 28050 Spain Email: luismiguel.conterasmurillo@telefonica.com Ishan Vaishnavi Huawei Technologies Dusseldorf GmBH Riesstrasse 25, Munich 80992 Germany Email: Ishan.vaishnavi@huawei.com Robert Szabo Ericsson Konyves Kaman krt. 11 Budapest, EMEA 1097 Hungary Phone: +36703135738 Email: robert.szabo@ericsson.com Bernardos, et al. Expires March 14, 2018 [Page 17]