--- 1/draft-ietf-teas-actn-framework-13.txt 2018-05-11 20:13:15.324769614 -0700 +++ 2/draft-ietf-teas-actn-framework-14.txt 2018-05-11 20:13:15.404771533 -0700 @@ -1,20 +1,20 @@ TEAS Working Group Daniele Ceccarelli (Ed) Internet Draft Ericsson Intended status: Informational Young Lee (Ed) -Expires: October 3, 2018 Huawei +Expires: November 11, 2018 Huawei - April 3, 2018 + May 11, 2018 Framework for Abstraction and Control of Traffic Engineered Networks - draft-ietf-teas-actn-framework-13 + draft-ietf-teas-actn-framework-14 Abstract Traffic Engineered networks have a variety of mechanisms to facilitate the separation of the data plane and control plane. They also have a range of management and provisioning protocols to configure and activate network resources. These mechanisms represent key technologies for enabling flexible and dynamic networking. The term "Traffic Engineered network" refers to a network that uses any connection-oriented technology under the control of a distributed or @@ -44,21 +44,21 @@ 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. - This Internet-Draft will expire on October 3, 2018. + This Internet-Draft will expire on November 11, 2018. Copyright Notice Copyright (c) 2018 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 @@ -69,98 +69,99 @@ warranty as described in the Simplified BSD License. Table of Contents 1. Introduction...................................................3 2. Overview.......................................................4 2.1. Terminology...............................................5 2.2. VNS Model of ACTN.........................................7 2.2.1. Customers............................................9 2.2.2. Service Providers...................................10 - 2.2.3. Network Providers...................................10 + 2.2.3. Network Operators...................................10 3. ACTN Base Architecture........................................10 3.1. Customer Network Controller..............................12 3.2. Multi-Domain Service Coordinator.........................13 3.3. Provisioning Network Controller..........................13 3.4. ACTN Interfaces..........................................14 4. Advanced ACTN Architectures...................................15 4.1. MDSC Hierarchy...........................................15 4.2. Functional Split of MDSC Functions in Orchestrators......16 5. Topology Abstraction Methods..................................17 5.1. Abstraction Factors......................................17 5.2. Abstraction Types........................................18 5.2.1. Native/White Topology...............................18 - 5.2.2. Black Topology......................................18 - 5.2.3. Grey Topology.......................................19 - 5.3. Methods of Building Grey Topologies......................20 + 5.2.2. Black Topology......................................19 + 5.2.3. Grey Topology.......................................20 + 5.3. Methods of Building Grey Topologies......................21 5.3.1. Automatic Generation of Abstract Topology by Configuration..............................................21 5.3.2. On-demand Generation of Supplementary Topology via Path Compute Request/Reply......................................21 5.4. Hierarchical Topology Abstraction Example................22 5.5. VN Recursion with Network Layers.........................24 6. Access Points and Virtual Network Access Points...............25 6.1. Dual-Homing Scenario.....................................27 7. Advanced ACTN Application: Multi-Destination Service..........28 7.1. Pre-Planned End Point Migration..........................29 7.2. On the Fly End-Point Migration...........................30 8. Manageability Considerations..................................30 8.1. Policy...................................................31 - 8.2. Policy Applied to the Customer Network Controller........31 - 8.3. Policy Applied to the Multi Domain Service Coordinator...32 + 8.2. Policy Applied to the Customer Network Controller........32 + 8.3. Policy Applied to the Multi-Domain Service Coordinator...32 8.4. Policy Applied to the Provisioning Network Controller....32 9. Security Considerations.......................................33 - 9.1. CNC-MDSC Interface (CMI).................................33 + 9.1. CNC-MDSC Interface (CMI).................................34 9.2. MDSC-PNC Interface (MPI).................................34 10. IANA Considerations..........................................34 - 11. References...................................................34 - 11.1. Informative References..................................34 - 12. Contributors.................................................35 + 11. References...................................................35 + 11.1. Informative References..................................35 + 12. Contributors.................................................36 Authors' Addresses...............................................37 APPENDIX A - Example of MDSC and PNC Functions Integrated in A Service/Network Orchestrator.....................................37 1. Introduction The term "Traffic Engineered network" refers to a network that uses any connection-oriented technology under the control of a distributed or centralized control plane to support dynamic provisioning of end-to-end connectivity. Traffic Engineered (TE) networks have a variety of mechanisms to facilitate separation of data plane and control plane including distributed signaling for path setup and protection, centralized path computation for planning and traffic engineering, and a range of management and provisioning protocols to configure and activate network resources. These mechanisms represent key technologies for enabling flexible and dynamic networking. Some examples of networks that are in scope of - this definition are optical networks, MPLS Transport Profile (MPLS- - TP) networks [RFC5654], and MPLS-TE networks [RFC2702]. + this definition are optical networks, Multiprotocol Label Switching + (MPLS) Transport Profile (MPLS-TP) networks [RFC5654], and MPLS-TE + networks [RFC2702]. One of the main drivers for Software Defined Networking (SDN) [RFC7149] is a decoupling of the network control plane from the data plane. This separation has been achieved for TE networks with the development of MPLS/GMPLS [RFC3945] and the Path Computation Element (PCE) [RFC4655]. One of the advantages of SDN is its logically centralized control regime that allows a global view of the underlying networks. Centralized control in SDN helps improve network resource utilization compared with distributed network control. For TE-based networks, a PCE may serve as a logically centralized path computation function. This document describes a set of management and control functions used to operate one or more TE networks to construct virtual networks that can be represented to customers and that are built from abstractions of the underlying TE networks so that, for example, a link in the customer's network is constructed from a path or collection of paths in the underlying networks. We call this set - of function "Abstraction and Control of Traffic Engineered Networks" - (ACTN). + of functions "Abstraction and Control of Traffic Engineered + Networks" (ACTN). 2. Overview Three key aspects that need to be solved by SDN are: . Separation of service requests from service delivery so that the configuration and operation of a network is transparent from the point of view of the customer, but remains responsive to the customer's services and business needs. @@ -198,24 +199,24 @@ specific technology islands) and presenting virtualized networks to their customers. The ACTN framework described in this document facilitates: . Abstraction of the underlying network resources to higher-layer applications and customers [RFC7926]. . Virtualization of particular underlying resources, whose selection criterion is the allocation of those resources to a - particular customer, application or service [ONF-ARCH]. + particular customer, application, or service [ONF-ARCH]. - . TE Network slicing of infrastructure to meet specific customers' - service requirements. + . TE Network slicing of infrastructure to meet specific + customers' service requirements. . Creation of an abstract environment allowing operators to view and control multi-domain networks as a single abstract network. . The presentation to customers of networks as a virtual network via open and programmable interfaces. 2.1. Terminology The following terms are used in this document. Some of them are @@ -226,21 +228,21 @@ we mean a part of an operator's network that is under common management. Network elements will often be grouped into domains based on technology types, vendor profiles, and geographic proximity. . Abstraction: This process is defined in [RFC7926]. . TE Network Slicing: In the context of ACTN, a TE network slice is a collection of resources that is used to establish a logically dedicated virtual network over one or more TE - network. TE Network slicing allows a network provider to + networks. TE network slicing allows a network operator to provide dedicated virtual networks for applications/customers over a common network infrastructure. The logically dedicated resources are a part of the larger common network infrastructures that are shared among various TE network slice instances which are the end-to-end realization of TE network slicing, consisting of the combination of physically or logically dedicated resources. . Node: A node is a vertex on the graph representation of a TE topology. In a physical network topology, a node corresponds @@ -260,113 +262,109 @@ topology. Two nodes connected by a link are said to be "adjacent" in the TE topology. In a physical network topology, a link corresponds to a physical connection. In an abstract network topology, a link (sometimes called an abstract link) is a representation of the potential to connect a pair of points with certain TE parameters (see [RFC7926] for details). Network abstraction may be applied recursively, so a link in one topology may be created by applying abstraction to the links in the underlying topology. - . Abstract Link: The term "abstract link" is defined in - [RFC7926]. - . Abstract Topology: The topology of abstract nodes and abstract links presented through the process of abstraction by a lower layer network for use by a higher layer network. . A Virtual Network (VN) is a network provided by a service provider to a customer for the customer to use in any way it wants as though it was a physical network. There are two views of a VN as follows: a) The VN can be abstracted as a set of edge-to-edge links (a Type 1 VN). Each link is referred as a VN member and is formed as an end-to-end tunnel across the underlying networks. Such tunnels may be constructed by recursive slicing or abstraction of paths in the underlying networks and can encompass edge points of the customer's network, access links, intra-domain paths, and inter-domain links. b) The VN can also be abstracted as a topology of virtual nodes - and virtual links (a Type 2 VN). The provider needs to map + and virtual links (a Type 2 VN). The operator needs to map the VN to actual resource assignment, which is known as virtual network embedding. The nodes in this case include physical end points, border nodes, and internal nodes as well as abstracted nodes. Similarly the links include physical access links, inter-domain links, and intra-domain links as well as abstract links. Clearly a Type 1 VN is a special case of a Type 2 VN. - . Access link: A link between a customer node and a provider + . Access link: A link between a customer node and a operator node. . Inter-domain link: A link between domains under distinct management administration. . Access Point (AP): An AP is a logical identifier shared between - the customer and the provider used to identify an access link. + the customer and the operator used to identify an access link. The AP is used by the customer when requesting a VNS. Note that the term "TE Link Termination Point" (LTP) defined in [TE-Topo] describes the end points of links, while an AP is a common identifier for the link itself. . VN Access Point (VNAP): A VNAP is the binding between an AP and a given VN. . Server Network: As defined in [RFC7926], a server network is a network that provides connectivity for another network (the Client Network) in a client-server relationship. 2.2. VNS Model of ACTN A Virtual Network Service (VNS) is the service agreement between a - customer and provider to provide a VN. When a VN is a simple + customer and operator to provide a VN. When a VN is a simple connectivity between two points, the difference between VNS and - connectivity service becomes blurred. - - There are three types of VNS defined in this document. + connectivity service becomes blurred. There are three types of VNS + defined in this document. o Type 1 VNS refers to a VNS in which the customer is allowed to create and operate a Type 1 VN. o Type 2a and 2b VNS refer to VNSs in which the customer is allowed to create and operates a Type 2 VN. With a Type 2a VNS, the VN is statically created at service configuration time and the customer is not allowed to change the topology (e.g., by adding or deleting abstract nodes and links). A Type 2b VNS is the same as a Type 2a VNS except that the customer is allowed to make dynamic changes to the initial topology created at service configuration time. VN Operations are functions that a customer can exercise on a VN - depending on the agreement between the customer and the provider. + depending on the agreement between the customer and the operator. o VN Creation allows a customer to request the instantiation of a VN. This could be through off-line pre-configuration or through dynamic requests specifying attributes to a Service Level Agreement (SLA) to satisfy the customer's objectives. o Dynamic Operations allow a customer to modify or delete the VN. The customer can further act upon the virtual network to create/modify/delete virtual links and nodes. These changes will result in subsequent tunnel management in the operator's networks. There are three key entities in the ACTN VNS model: - Customers - Service Providers - - Network Providers + - Network Operators These entities are related in a three tier model as shown in Figure 1. +----------------------+ | Customer | +----------------------+ | VNS || | /\ VNS Request || | || Reply @@ -364,29 +362,30 @@ These entities are related in a three tier model as shown in Figure 1. +----------------------+ | Customer | +----------------------+ | VNS || | /\ VNS Request || | || Reply \/ | || + +----------------------+ | Service Provider | +----------------------+ / | \ / | \ / | \ / | \ +------------------+ +------------------+ +------------------+ - |Network Provider 1| |Network Provider 2| |Network Provider 3| + |Network Operator 1| |Network Operator 2| |Network Operator 3| +------------------+ +------------------+ +------------------+ Figure 1: The Three Tier Model. The commercial roles of these entities are described in the following sections. 2.2.1. Customers Basic customers include fixed residential users, mobile users, and @@ -399,53 +398,55 @@ companies. Such customers ask for both point-to point and multipoint connectivity with high resource demands varying significantly in time. This is one of the reasons why a bundled service offering is not enough and it is desirable to provide each advanced customer with a customized virtual network service. Advanced customers may also have the ability to modify their service parameters within the scope of their virtualized environments. The primary focus of ACTN is Advanced Customers. As customers are geographically spread over multiple network - provider domains, they have to interface to multiple providers and + operator domains, they have to interface to multiple operators and may have to support multiple virtual network services with different - underlying objectives set by the network providers. To enable these + underlying objectives set by the network operators. To enable these customers to support flexible and dynamic applications they need to control their allocated virtual network resources in a dynamic fashion, and that means that they need a view of the topology that - spans all of the network providers. Customers of a given service + spans all of the network operators. Customers of a given service provider can in turn offer a service to other customers in a recursive way. 2.2.2. Service Providers In the scope of ACTN, service providers deliver VNSs to their customers. Service providers may or may not own physical network - resources (i.e., may or may not be network providers as described in + resources (i.e., may or may not be network operators as described in Section 2.2.3). When a service provider is the same as the network - provider, this is similar to existing VPN models applied to a single - provider although it may be hard to use this approach when the - customer spans multiple independent network provider domains. + operator, this is similar to existing VPN models applied to a single + operator although it may be hard to use this approach when the + customer spans multiple independent network operator domains. - When network providers supply only infrastructure, while distinct + When network operators supply only infrastructure, while distinct service providers interface to the customers, the service providers - are themselves customers of the network infrastructure providers. + are themselves customers of the network infrastructure operators. One service provider may need to keep multiple independent network - providers because its end-users span geographically across multiple - network provider domains. + operators because its end-users span geographically across multiple + network operator domains. In some cases, service provider is also a + network operator when it owns network infrastructure on which + service is provided. -2.2.3. Network Providers +2.2.3. Network Operators - Network Providers are the infrastructure providers that provision + Network operators are the infrastructure operators that provision the network resources and provide network resources to their customers. The layered model described in this architecture - separates the concerns of network providers and customers, with + separates the concerns of network operators and customers, with service providers acting as aggregators of customer requests. 3. ACTN Base Architecture This section provides a high-level model of ACTN showing the interfaces and the flow of control between components. The ACTN architecture is based on a 3-tier reference model and allows for hierarchy and recursion. The main functionalities within an ACTN system are: @@ -463,64 +464,65 @@ This function includes network path computation based on customer service connectivity request constraints, path computation based on the global network-wide abstracted topology, and the creation of an abstracted view of network resources allocated to each customer. These operations depend on customer-specific network objective functions and customer traffic profiles. . Customer mapping/translation: This function is to map customer requests/commands into network provisioning requests that can - be sent to the Provisioning Network Controller (PNC) according - to business policies provisioned statically or dynamically at - the OSS/NMS. Specifically, it provides mapping and translation - of a customer's service request into a set of parameters that - are specific to a network type and technology such that network + be sent from the Multi-Domain Service Coordinator (MDSC) to the + Provisioning Network Controller (PNC) according to business + policies provisioned statically or dynamically at the OSS/NMS. + Specifically, it provides mapping and translation of a + customer's service request into a set of parameters that are + specific to a network type and technology such that network configuration process is made possible. . Virtual service coordination: This function translates customer service-related information into virtual network service operations in order to seamlessly operate virtual networks while meeting a customer's service requirements. In the context of ACTN, service/virtual service coordination includes a number of service orchestration functions such as multi- destination load balancing, guarantees of service quality, bandwidth and throughput. It also includes notifications for service fault and performance degradation and so forth. The base ACTN architecture defines three controller types and the corresponding interfaces between these controllers. The following types of controller are shown in Figure 2: . CNC - Customer Network Controller - . MDSC - Multi Domain Service Coordinator + . MDSC - Multi-Domain Service Coordinator . PNC - Provisioning Network Controller Figure 2 also shows the following interfaces: . CMI - CNC-MDSC Interface . MPI - MDSC-PNC Interface - . SBI - South Bound Interface + . SBI - Southbound Interface +---------+ +---------+ +---------+ | CNC | | CNC | | CNC | +---------+ +---------+ +---------+ \ | / - Business \ | / - Boundary =============\==============|==============/============ + \ | / + Boundary =============\==================|=====================/======= Between \ | / - Customer & ------- | CMI ------- - Network Provider \ | / + Customer & ----------- | CMI -------------- + Network Operator \ | / +---------------+ | MDSC | +---------------+ / | \ - ------------ | MPI ------------- + ------------ | MPI --------------- / | \ +-------+ +-------+ +-------+ | PNC | | PNC | | PNC | +-------+ +-------+ +-------+ | SBI / | / \ | / | SBI SBI / \ --------- ----- | / \ ( ) ( ) | / \ - Control - ( Phys. ) | / ----- ( Plane ) ( Net ) | / ( ) @@ -532,39 +534,39 @@ ----- ----- Figure 2: ACTN Base Architecture Note that this is a functional architecture: an implementation and deployment might collocate one or more of the functional components. 3.1. Customer Network Controller A Customer Network Controller (CNC) is responsible for communicating - a customer's VNS requirements to the network provider over the CNC- + a customer's VNS requirements to the network operator over the CNC- MDSC Interface (CMI). It has knowledge of the end-points associated with the VNS (expressed as APs), the service policy, and other QoS information related to the service. As the Customer Network Controller directly interfaces to the applications, it understands multiple application requirements and their service needs. The capability of a CNC beyond its CMI role is outside the scope of ACTN and may be implemented in different ways. For example, the CNC may in fact be a controller or part of a controller in the customer's domain, or the CNC functionality could - also be implemented as part of a provisioning portal. + also be implemented as part of a service provider's portal. 3.2. Multi-Domain Service Coordinator A Multi-Domain Service Coordinator (MDSC) is a functional block that implements all of the ACTN functions listed in Section 3 and described further in Section 4.2. The two functions of the MDSC, - namely, multi domain coordination and virtualization/abstraction are + namely, multi-domain coordination and virtualization/abstraction are referred to as network-related functions while the other two functions, namely, customer mapping/translation and virtual service coordination are referred to as service-related functions. The MDSC sits at the center of the ACTN model between the CNC that issues connectivity requests and the Provisioning Network Controllers (PNCs) that manage the network resources. The key point of the MDSC (and of the whole ACTN framework) is detaching the network and service control from underlying technology to help the customer express the network as desired by business needs. The MDSC envelopes the instantiation of the right technology @@ -572,21 +574,21 @@ controls and manages the primitives to achieve functionalities as desired by the CNC. In order to allow for multi-domain coordination a 1:N relationship must be allowed between MDSCs and PNCs. In addition to that, it could also be possible to have an M:1 relationship between MDSCs and PNC to allow for network resource partitioning/sharing among different customers not necessarily connected to the same MDSC (e.g., different service providers) but - all using the resources of a common network infrastructure provider. + all using the resources of a common network infrastructure operator. 3.3. Provisioning Network Controller The Provisioning Network Controller (PNC) oversees configuring the network elements, monitoring the topology (physical or virtual) of the network, and collecting information about the topology (either raw or abstracted). The PNC functions can be implemented as part of an SDN domain controller, a Network Management System (NMS), an Element Management @@ -611,39 +613,39 @@ (_ _) (_ _) (_ _) (_ _) (_______) (_______) Figure 3: PNC Domain Borders 3.4. ACTN Interfaces Direct customer control of transport network elements and virtualized services is not a viable proposition for network - providers due to security and policy concerns. In addition, some + operators due to security and policy concerns. In addition, some networks may operate a control plane and as such it is not practical for the customer to directly interface with network elements. Therefore, the network has to provide open, programmable interfaces, through which customer applications can create, replace and modify virtual network resources and services in an interactive, flexible and dynamic fashion. Three interfaces exist in the ACTN architecture as shown in Figure 2. . CMI: The CNC-MDSC Interface (CMI) is an interface between a CNC and an MDSC. The CMI is a business boundary between customer - and network provider. It is used to request a VNS for an + and network operator. It is used to request a VNS for an application. All service-related information is conveyed over this interface (such as the VNS type, topology, bandwidth, and service constraints). Most of the information over this - interface is agnostic of the technology used by Network - Providers, but there are some cases (e.g., access link + interface is agnostic of the technology used by network + operators, but there are some cases (e.g., access link configuration) where it is necessary to specify technology- specific details. . MPI: The MDSC-PNC Interface (MPI) is an interface between an MDSC and a PNC. It communicates requests for new connectivity or for bandwidth changes in the physical network. In multi- domain environments, the MDSC needs to communicate with multiple PNCs each responsible for control of a domain. The MPI presents an abstracted topology to the MDSC hiding technology specific aspects of the network and hiding topology @@ -665,33 +667,35 @@ are scalability, administrative choices, or putting together different layers and technologies in the network. In the case where there is a hierarchy of MDSCs, we introduce the terms higher-level MDSC (MDSC-H) and lower-level MDSC (MDSC-L). The interface between them is a recursion of the MPI. An implementation of an MDSC-H makes provisioning requests as normal using the MPI, but an MDSC-L must be able to receive requests as normal at the CMI and also at the MPI. The hierarchy of MDSCs can be seen in Figure 4. Another implementation choice could foresee the usage of an MDSC-L - for all the PNCs related to a given technology (e.g. IP/MPLS) and a - different MDSC-L for the PNCs related to another technology (e.g. - OTN/WDM) and an MDSC-H to coordinate them. + for all the PNCs related to a given technology (e.g., Internet + Protocol (IP)/Multiprotocol Label Switching (MPLS)) and a different + MDSC-L for the PNCs related to another technology (e.g., Optical + Transport Network (OTN)/Wavelength Division Multiplexing (WDM)) and + an MDSC-H to coordinate them. +--------+ | CNC | +--------+ | +-----+ | CMI | CNC | +----------+ +-----+ + -------| MDSC-H |---- | | +----------+ | | CMI - MPI | MPI | | | | | +---------+ +---------+ | MDSC-L | | MDSC-L | +---------+ +---------+ MPI | | | | | | | | ----- ----- ----- ----- | PNC | | PNC | | PNC | | PNC | ----- ----- ----- ----- @@ -699,23 +703,23 @@ Figure 4: MDSC Hierarchy 4.2. Functional Split of MDSC Functions in Orchestrators An implementation choice could separate the MDSC functions into two groups, one group for service-related functions and the other for network-related functions. This enables the implementation of a service orchestrator that provides the service-related functions of the MDSC and a network orchestrator that provides the network- related functions of the MDSC. This split is consistent with the - YANG service model architecture described in [Service-YANG]. Figure - 5 depicts this and shows how the ACTN interfaces may map to YANG - models. + Yet Another Next Generation (YANG) service model architecture + described in [Service-YANG]. Figure 5 depicts this and shows how + the ACTN interfaces may map to YANG models. +--------------------+ | Customer | | +-----+ | | | CNC | | | +-----+ | +--------------------+ CMI | Customer Service Model | +---------------------------------------+ @@ -762,23 +766,24 @@ available topology to the MDSC, or by an MDSC-L when presenting topology to an MDSC-H. This function is different to the creation of a VN (and particularly a Type 2 VN) which is not abstraction but construction of virtual resources. 5.1. Abstraction Factors As discussed in [RFC7926], abstraction is tied with policy of the networks. For instance, per an operational policy, the PNC would not provide any technology specific details (e.g., optical - parameters for WSON) in the abstract topology it provides to the - MDSC. Similarly, policy of the networks may determine the - abstraction type as described in Section 5.2. + parameters for Wavelength Switched Optical Network (WSON) in the + abstract topology it provides to the MDSC. Similarly, policy of the + networks may determine the abstraction type as described in Section + 5.2. There are many factors that may impact the choice of abstraction: - Abstraction depends on the nature of the underlying domain networks. For instance, packet networks may be abstracted with fine granularity while abstraction of optical networks depends on the switching units (such as wavelengths) and the end-to-end continuity and cross-connect limitations within the network. - Abstraction also depends on the capability of the PNCs. As @@ -809,21 +814,21 @@ This section defines the following three types of topology abstraction: . Native/White Topology (Section 5.2.1) . Black Topology (Section 5.2.2) . Grey Topology (Section 5.2.3) 5.2.1. Native/White Topology This is a case where the PNC provides the actual network topology to - the MDSC without any hiding or filtering of information. I.e., no + the MDSC without any hiding or filtering of information, i.e., no abstraction is performed. In this case, the MDSC has the full knowledge of the underlying network topology and can operate on it directly. 5.2.2. Black Topology A black topology replaces a full network with a minimal representation of the edge-to-edge topology without disclosing any node internal connectivity information. The entire domain network may be abstracted as a single abstract node with the network's @@ -867,24 +872,24 @@ 5.2.3. Grey Topology A grey topology represents a compromise between black and white topologies from a granularity point of view. In this case, the PNC exposes an abstract topology containing all PNC domains border nodes and an abstraction of the connectivity between those border nodes. This abstraction may contain either physical or abstract nodes/links. - Two modes of grey topology are identified: - . In a type A grey topology type border nodes are connected by a - full mesh of TE links (see Figure 7). - . In a type B grey topology border nodes are connected over a + Two types of grey topology are identified: + . In a type A grey topology, border nodes are connected by a full + mesh of TE links (see Figure 7). + . In a type B grey topology, border nodes are connected over a more detailed network comprising internal abstract nodes and abstracted links. This mode of abstraction supplies the MDSC with more information about the internals of the PNC domain and allows it to make more informed choices about how to route connectivity over the underlying network. ..................................... : PNC Domain : : +--+ +--+ +--+ +--+ : ------+ +-----+ +-----+ +-----+ +------ @@ -956,33 +961,31 @@ when the MDSC needs to create a new VN, the MDSC can issue path computation requests to PNCs with constraints matching the VN request as described in [ACTN-YANG]. An example is provided in Figure 8, where the MDSC is creating a P2P VN between AP1 and AP2. The MDSC could use two different inter-domain links to get from Domain X to Domain Y, but in order to choose the best end-to-end path it needs to know what domain X and Y can offer in terms of connectivity and constraints between the PE nodes and the border nodes. - ------- -------- + ------- ------- ( ) ( ) - BrdrX.1------- BrdrY.1 - (+---+ ) ( +---+) - -+---( |PE1| Dom.X ) ( Dom.Y |PE2| )---+- | (+---+ ) ( +---+) | AP1 - BrdrX.2------- BrdrY.2 - AP2 ( ) ( ) ------- -------- Figure 8: A Multi-Domain Example - The MDSC issues a path computation request to PNC.X asking for potential connectivity between PE1 and border node BrdrX.1 and between PE1 and BrdrX.2 with related objective functions and TE metric constraints. A similar request for connectivity from the border nodes in Domain Y to PE2 will be issued to PNC.Y. The MDSC merges the results to compute the optimal end-to-end path including the inter domain links. The MDSC can use the result of this computation to request the PNCs to provision the underlying networks, and the MDSC can then use the end-to-end path as a virtual link in the VN it delivers to the customer. @@ -1057,53 +1060,54 @@ black topology abstraction to MSDC-H in which each PNC domain is presented as a single virtual node. MDSC-H combines these two topologies to create the abstraction topology on which it operates. MDSC-H sees the whole four domain networks as four virtual nodes connected via virtual links. 5.5. VN Recursion with Network Layers In some cases the VN supplied to a customer may be built using resources from different technology layers operated by different - providers. For example, one provider may run a packet TE network - and use optical connectivity provided by another provider. + operators. For example, one operator may run a packet TE network + and use optical connectivity provided by another operator. As shown in Figure 10, a customer asks for end-to-end connectivity between CE A and CE B, a virtual network. The customer's CNC makes a - request to Provider 1's MDSC. The MDSC works out which network + request to Operator 1's MDSC. The MDSC works out which network resources need to be configured and sends instructions to the appropriate PNCs. However, the link between Q and R is a virtual - link supplied by Provider 2: Provider 1 is a customer of Provider 2. + link supplied by Operator 2: Operator 1 is a customer of Operator 2. - To support this, Provider 1 has a CNC that communicates to Provider - 2's MDSC. Note that Provider 1's CNC in Figure 10 is a functional + To support this, Operator 1 has a CNC that communicates to Operator + 2's MDSC. Note that Operator 1's CNC in Figure 10 is a functional component that does not dictate implementation: it may be embedded in a PNC. Virtual CE A o===============================o CE B Network ----- CNC wants to create a VN Customer | CNC | between CE A and CE B ----- : *********************************************** : - Provider 1 --------------------------- + Operator 1 --------------------------- | MDSC | --------------------------- : : : : : : ----- ------------- ----- | PNC | | PNC | | PNC | ----- ------------- ----- : : : : : + Higher v v : v v Layer CE A o---P-----Q===========R-----S---o CE B Network | : | | : | | ----- | | | CNC | | | ----- | | : | *********************************************** | : | @@ -1100,33 +1104,36 @@ Higher v v : v v Layer CE A o---P-----Q===========R-----S---o CE B Network | : | | : | | ----- | | | CNC | | | ----- | | : | *********************************************** | : | - - Provider 2 | ------ | + Operator 2 | ------ | | | MSDC | | | ------ | | : | | ------- | | | PNC | | | ------- | \ : : : / Lower \v v v/ Layer X--Y--Z Network + Where + --- is a link + === is a virtual link + Figure 10: VN recursion with Network Layers 6. Access Points and Virtual Network Access Points In order to map identification of connections between the customer's sites and the TE networks and to scope the connectivity requested in the VNS, the CNC and the MDSC refer to the connections using the Access Point (AP) construct as shown in Figure 11. ------------- @@ -1177,58 +1184,58 @@ +----------+------------------------+ |End Point | Access Link Bandwidth | +-----+----------+----------+-------------+ |AP id| PE,port | MaxResBw | AvailableBw | +-----+----------+----------+-------------+ | AP1 |PE1,portW | 10Gbps | 10Gbps | +-----+----------+----------+-------------+ | AP2 |PE2,portY | 40Gbps | 40Gbps | +-----+----------+----------+-------------+ - Table 2: AP - Provider View + Table 2: AP - Operator View A Virtual Network Access Point (VNAP) needs to be defined as binding between an AP and a VN. It is used to allow for different VNs to - start from the same AP. "It also allows for traffic engineering on + start from the same AP. It also allows for traffic engineering on the access and/or inter-domain links (e.g., keeping track of bandwidth allocation). A different VNAP is created on an AP for each VN. In this simple scenario we suppose we want to create two virtual networks. The first with VN identifier 9 between AP1 and AP2 with bandwidth of 1Gbps, while the second with VN identifier 5, again between AP1 and AP2 and with bandwidth 2Gbps. - The provider view would evolve as shown in Table 3. + The operator view would evolve as shown in Table 3. +----------+------------------------+ |End Point | Access Link/VNAP Bw | +---------+----------+----------+-------------+ |AP/VNAPid| PE,port | MaxResBw | AvailableBw | +---------+----------+----------+-------------+ |AP1 |PE1,portW | 10Gbps | 7Gbps | | -VNAP1.9| | 1Gbps | N.A. | | -VNAP1.5| | 2Gbps | N.A | +---------+----------+----------+-------------+ |AP2 |PE2,portY | 40Gbps | 37Gbps | | -VNAP2.9| | 1Gbps | N.A. | | -VNAP2.5| | 2Gbps | N.A | +---------+----------+----------+-------------+ - Table 3: AP and VNAP - Provider View after VNS Creation + Table 3: AP and VNAP - Operator View after VNS Creation 6.1. Dual-Homing Scenario Often there is a dual homing relationship between a CE and a pair of - PEs. This case needs to be supported by the definition of VN, APs + PEs. This case needs to be supported by the definition of VN, APs, and VNAPs. Suppose CE1 connected to two different PEs in the - operator domain via AP1 and AP2 and that the customer needs 5Gbps of - bandwidth between CE1 and CE2. This is shown in Figure 12. + operator domain via AP1 and AP2 and that the customer needs 5 Gbps + of bandwidth between CE1 and CE2. This is shown in Figure 12. ____________ AP1 ( ) AP3 -------(PE1) (PE3)------- W / ( ) \ X +---+/ ( ) \+---+ |CE1| ( ) |CE2| +---+\ ( ) /+---+ Y \ ( ) / Z -------(PE2) (PE4)------- @@ -1248,38 +1255,37 @@ |End Point | Access Link/VNAP Bw | +---------+----------+----------+-------------+-----------+ |AP/VNAPid| CE,port | MaxResBw | AvailableBw |Dual Homing| +---------+----------+----------+-------------+-----------+ |AP1 |CE1,portW | 10Gbps | 5Gbps | | | -VNAP1.9| | 5Gbps | N.A. | VNAP2.9 | +---------+----------+----------+-------------+-----------+ |AP2 |CE1,portY | 40Gbps | 35Gbps | | | -VNAP2.9| | 5Gbps | N.A. | VNAP1.9 | +---------+----------+----------+-------------+-----------+ - |AP3 |CE2,portX | 40Gbps | 35Gbps | | + |AP3 |CE2,portX | 50 Gbps | 45 Gbps | | | -VNAP3.9| | 5Gbps | N.A. | NONE | +---------+----------+----------+-------------+-----------+ Table 4: Dual-Homing - Customer View after VN Creation 7. Advanced ACTN Application: Multi-Destination Service A further advanced application of ACTN is in the case of Data Center selection, where the customer requires the Data Center selection to be based on the network status; this is referred to as Multi- Destination in [ACTN-REQ]. In terms of ACTN, a CNC could request a VNS between a set of source APs and destination APs and leave it up to the network (MDSC) to decide which source and destination access - points to be used to set up the VNS. The candidate list of - source and destination APs is decided by a CNC (or an entity outside - of ACTN) based on certain factors which are outside the scope of - ACTN. + points to be used to set up the VNS. The candidate list of source + and destination APs is decided by a CNC (or an entity outside of + ACTN) based on certain factors which are outside the scope of ACTN. Based on the AP selection as determined and returned by the network (MDSC), the CNC (or an entity outside of ACTN) should further take care of any subsequent actions such as orchestration or service setup requirements. These further actions are outside the scope of ACTN. Consider a case as shown in Figure 14, where three data centers are available, but the customer requires the data center selection to be based on the network status and the connectivity service setup @@ -1333,25 +1339,25 @@ |DC-D| |DC-C|<------------- +----+ +----+ Figure 15: Pre-planned End-Point Migration 7.2. On the Fly End-Point Migration Compared to pre-planned end point migration, on the fly end point selection is dynamic in that the migration is not pre-planned but decided based on network condition. Under this scenario, the MDSC - would monitor the network (based on the VN SLA) and notify the CNC - in case where some other destination AP would be a better choice - based on the network parameters. The CNC should instruct the MDSC - when it is suitable to update the VN with the new AP if it is - required. + would monitor the network (based on the VN Service-level Agreement + (SLA) and notify the CNC in case where some other destination AP + would be a better choice based on the network parameters. The CNC + should instruct the MDSC when it is suitable to update the VN with + the new AP if it is required. 8. Manageability Considerations The objective of ACTN is to manage traffic engineered resources, and provide a set of mechanisms to allow customers to request virtual connectivity across server network resources. ACTN supports multiple customers each with its own view of and control of a virtual network built on the server network, the network operator will need to partition (or "slice") their network resources, and manage the resources accordingly. @@ -1412,21 +1418,21 @@ 8.2. Policy Applied to the Customer Network Controller A virtual network service for a customer application will be requested by the CNC. The request will reflect the application requirements and specific service needs, including bandwidth, traffic type and survivability. Furthermore, application access and type of virtual network service requested by the CNC, will be need adhere to specific access control policies. -8.3. Policy Applied to the Multi Domain Service Coordinator +8.3. Policy Applied to the Multi-Domain Service Coordinator A key objective of the MDSC is to support the customer's expression of the application connectivity request via its CNC as set of desired business needs, therefore policy will play an important role. Once authorized, the virtual network service will be instantiated via the CNC-MDSC Interface (CMI), it will reflect the customer application and connectivity requirements, and specific service transport needs. The CNC and the MDSC components will have agreed @@ -1479,24 +1485,24 @@ Several distributed ACTN functional components are required, and implementations should consider encrypting data that flows between components, especially when they are implemented at remote nodes, regardless these data flows are on external or internal network interfaces. The ACTN security discussion is further split into two specific categories described in the following sub-sections: - . Interface between the Customer Network Controller and Multi + . Interface between the Customer Network Controller and Multi- Domain Service Coordinator (MDSC), CNC-MDSC Interface (CMI) - . Interface between the Multi Domain Service Coordinator and + . Interface between the Multi-Domain Service Coordinator and Provisioning Network Controller (PNC), MDSC-PNC Interface (MPI) From a security and reliability perspective, ACTN may encounter many risks such as malicious attack and rogue elements attempting to connect to various ACTN components. Furthermore, some ACTN components represent a single point of failure and threat vector, and must also manage policy conflicts, and eavesdropping of communication between different ACTN components. The conclusion is that all protocols used to realize the ACTN @@ -1528,46 +1534,46 @@ functions of the MDSC. 9.2. MDSC-PNC Interface (MPI) Where the MDSC must interact with multiple (distributed) PNCs, a PKI-based mechanism is suggested, such as building a TLS or HTTPS connection between the MDSC and PNCs, to ensure trust between the physical network layer control components and the MDSC. Which MDSC the PNC exports topology information to, and the level of - detail (full or abstracted) should also be authenticated and - specific access restrictions and topology views, should be + detail (full or abstracted), should also be authenticated, and + specific access restrictions and topology views should be configurable and/or policy-based. 10. IANA Considerations This document has no actions for IANA. 11. References 11.1. Informative References [RFC2702] Awduche, D., et. al., "Requirements for Traffic - Engineering Over MPLS", RFC 2702, October 1999. + Engineering Over MPLS", RFC 2702, September 1999. [RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path Computation Element (PCE)-Based Architecture", IETF RFC 4655, August 2006. [RFC5654] Niven-Jenkins, B. (Ed.), D. Brungard (Ed.), and M. Betts (Ed.), "Requirements of an MPLS Transport Profile", RFC - 5654, October 2009. + 5654, September 2009. [RFC7149] Boucadair, M. and Jacquenet, C., "Software-Defined Networking: A Perspective from within a Service Provider - Environment", RFC 7149, April 2014. + Environment", RFC 7149, March 2014. [RFC7926] A. Farrel (Ed.), "Problem Statement and Architecture for Information Exchange between Interconnected Traffic- Engineered Networks", RFC 7926, July 2016. [RFC3945] Manning, E., et al., "Generalized Multi-Protocol Label Switching (GMPLS) Architecture2, RFC 3945, October 2004. [ONF-ARCH] Open Networking Foundation, "SDN architecture", Issue 1.1, ONF TR-521, June 2016.