OPSAWG M. Boucadair, Ed. Internet-Draft Orange Intended status: Standards Track O. Gonzalez de Dios Expires: 22 September 2022 S. Barguil Telefonica Q. Wu Huawei V. Lopez Nokia 21 March 2022 A Network YANG Model for Service Attachment Points (SAPs) draft-ietf-opsawg-sap-03 Abstract This document defines a YANG data model for representing an abstract view of the provider network topology that contains the points from which its services can be attached (e.g., basic connectivity, VPN, network slices). Also, the model can be used to retrieve the points where the services are actually being delivered to customers (including peer networks). This document augments the 'ietf-network' data model by adding the concept of Service Attachment Points (SAPs). The Service Attachment Points are the network reference points to which network services, such as Layer 3 Virtual Private Network (L3VPN) or Layer 2 Virtual Private Network (L2VPN), can be attached. Both User-Network Interface (UNI) and Network-to-Network Interface (NNI) are supported in the SAP data model. 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 https://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 22 September 2022. Boucadair, et al. Expires 22 September 2022 [Page 1] Internet-Draft A Network YANG for SAPs March 2022 Copyright Notice Copyright (c) 2022 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 (https://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 to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. SAP Network Model Usage . . . . . . . . . . . . . . . . . . . 4 4. Relationship to Other YANG Data Models . . . . . . . . . . . 8 5. SAP Module Tree Structure . . . . . . . . . . . . . . . . . . 9 6. SAP YANG Module . . . . . . . . . . . . . . . . . . . . . . . 12 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19 8. Security Considerations . . . . . . . . . . . . . . . . . . . 19 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 20 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 20 10.1. Normative References . . . . . . . . . . . . . . . . . . 20 10.2. Informative References . . . . . . . . . . . . . . . . . 22 Appendix A. A Simplified SAP Network Example . . . . . . . . . . 24 Appendix B. A Simple Example of SAP Network Model: Node Filter . . . . . . . . . . . . . . . . . . . . . . . . . 27 Appendix C. An Example of NNI SAP: Inter-AS VPN Option A . . . . 32 Appendix D. An Example of Using the SAP Network Model in Service Creation . . . . . . . . . . . . . . . . . . . . . . . . 35 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 35 1. Introduction From the perspective of a service provider, the Service Attachment Points (SAPs) are abstraction of the network reference points where network services can be delivered to customers. The SAP is an important architectural concept in many implementations and service deployments, such as Virtual Private Networks (VPNs), Software- Defined Wide Area Network (SDWAN) [I-D.ietf-bess-bgp-sdwan-usage], or network slices [I-D.ietf-teas-ietf-network-slices]. For example, this concept is used to decide where to attach and, thus, deliver the service in the Layer 3 VPN Service Model (L3SM) [RFC8299] and the Layer 2 VPN Service Model (L2SM) [RFC8466]. It can also be used to Boucadair, et al. Expires 22 September 2022 [Page 2] Internet-Draft A Network YANG for SAPs March 2022 retrieve where services, such as the Layer 3 VPN Network Model (L3NM) [RFC9182], and the Layer 2 VPN Network Model (L2NM) [I-D.ietf-opsawg-l2nm], are delivered to customers. This document defines a YANG network model (Section 6) for representing, managing, and controlling the SAPs. The data model augments the 'ietf-network' module [RFC8345] by adding the concept of SAPs. This document explains the scope and purpose of a SAP network model and its relation with other models (Section 4). Multiple service types can be associated with a given network. Whether a SAP topology is dedicated to a specific service or shared among many services is deployment specific. This document supports both deployment schemes. This document does not make any assumption about the service(s) provided by a network to its users. VPN services (e.g., Layer 3 Virtual Private Network (L3VPN) or Layer 2 Virtual Private Network (L2VPN)) are used for illustration purposes (Appendices A and B). Both User-Network Interface (UNI) and Network-to-Network Interface (NNI) SAPs are supported in the document. An example of NNI usage is provided in Appendix C. The YANG data model in Section 6 conforms to the Network Management Datastore Architecture (NMDA) [RFC8342]. 2. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119][RFC8174] when, and only when, they appear in all capitals, as shown here. This document assumes that the reader is familiar with the contents of [RFC6241], [RFC7950], [RFC8345], and [RFC8309]. The document uses terms from those documents. The meanings of the symbols in tree diagrams are defined in [RFC8340]. This document uses the term "network model" defined in Section 2.1 of [RFC8969]. This document uses the following terms: Service povider: The organization responsible for operating the Boucadair, et al. Expires 22 September 2022 [Page 3] Internet-Draft A Network YANG for SAPs March 2022 network that offers a service (e.g., a VPN) to customers. Customer Edge (CE): An equipment that is dedicated to a particular customer and is directly connected to one or more Provider Edges (PEs) via attachment circuits (ACs). A CE is usually located at the customer premises. A CE may be dedicated to a single service (e.g., L3VPN), although it may support multiple VPNs if each one has separate attachment circuits. A CE can be a router, a bridge, a switch, etc. Provider Edge (PE): An equipment owned and managed by the service provider that can support multiple services (e.g., VPNs) for different customers. A PE is directly connected to one or more CEs via ACs. Service Attachment Point (SAP): Describes the service's endpoint characteristics and its reference to a Termination Point (TP). 3. SAP Network Model Usage Management operations of a service provider network can be automated using a variety of means such as interfaces based on YANG modules [RFC8969]. From that standpoint, and considering the architecture depicted in Figure 1, a goal of this document is to provide a mechanism to show via a YANG-based interface an abstracted network view from the network controller to the service orchestration layer with a focus on where a service can be delivered to customers. The model is also used to retrieve the network points where a service is being delivered to customers. For services that require resources from peer networks, the module can also be used to expose NNIs. Boucadair, et al. Expires 22 September 2022 [Page 4] Internet-Draft A Network YANG for SAPs March 2022 +-----------------+ | Customer | +--------+--------+ Customer Service Models | (e.g., L3SM, L2SM) | +--------+--------+ | Service | | Orchestration | +------+---+------+ Network Models | | SAP Network Model (e.g., L3NM, L2NM) | | +------+---+------+ | Network | | Controller | +--------+--------+ | +---------------------+---------------------+ | Network | +-------------------------------------------+ Figure 1: SAP Network Model Usage Let us consider the example of a typical service provider network (Figure 2), with PE and P nodes. .---------. .---------. | PE1 | | PE2 | '---------' '---------' \ / .------. | P(s) | '------' / \ .---------. .---------. | PE3 | | PE4 | '---------' '---------' Figure 2: Sample Network Topology The service orchestration layer does not need to know about the internals of the underlying network (e.g., P nodes). Figure 3 shows the abstract network view as seen by a service orchestrator. However, this view is not enough to provide to the service orchestration layer the information to create services in the network. The service topology need is to be able to expose the set of nodes and the attachment points associated with the nodes from which network services can be grafted (delivered). Boucadair, et al. Expires 22 September 2022 [Page 5] Internet-Draft A Network YANG for SAPs March 2022 .---------. .---------. | PE1 | | PE2 | '---------' '---------' .---------. .---------. | PE3 | | PE4 | '---------' '---------' Figure 3: Abstract Network Topology Typically, and focusing on the UNIs, the service orchestration layer would see a set of PEs and a set of client-facing interfaces (physical or logical) to which CEs can be connected (or are actually connected). The service orchestration layer can use these interfaces to setup the requested services or to commit the delivery of a service. Figure 4 depicts a sample SAP network topology that is maintained by the network controller and exposed to the service orchestration. .-+-. .-+-. .-+-. .-+-. .-+-. .-|sap|-|sap|-|sap|-. .-|sap|-------|sap|-. | '---' '---' '---' | | '---' '---' | .---. | | | |sap| PE1 | | PE2 | '---' | | | | | | | '-------------------' '-------------------' .-------------------. .-------------------. | | | | | | | .---. | PE3 | | PE4 |sap| | | | '---' | .---. .---. .---. | | .---. .---. .---. | '-|sap|-|sap|-|sap|-' '-|sap|-|sap|-|sap|-' '-+-' '-+-' '-+-' '-+-' '-+-' '-+-' Figure 4: SAP Network Topology A single SAP network topology can be used for one or multiple service types (e.g., L3VPN, Ethernet VPN (EVPN)). The network controller can, then, expose the service type(s) and associated interfaces via the SAPs. Boucadair, et al. Expires 22 September 2022 [Page 6] Internet-Draft A Network YANG for SAPs March 2022 As shown in Figure 5, the service orchestration layer will have also access to a set of customer service model (e.g., the L3SM or the L2SM) in the customer-facing interface and a set of network models (e.g., the L3NM and network topology data models) in the resource- facing interface. In this use case, it is assumed that the network controller is unaware of what happens beyond the PEs towards the CEs; it is only responsible for the management and control of the SAPs and the network between PEs. In order to correlate between delivery points expressed in service requests and SAPs, the SAP model may include a peer customer point identifier. That identifier can be a CE identifier, a site identifier, etc. .---. |CE2| '-+-' | .-+-. .-+-. .-+-. .-+-. .-+-. .-|sap|-|sap|-|sap|-. .-|sap|-------|sap|-. | '---' '---' '---' | | '---' '---' | .---. .---. | | | |CE1+--+sap| PE1 | | PE2 | '---' '---' | | | | | | | '-------------------' '-------------------' .-------------------. .-------------------. | | | | | | | .---. .---. | PE3 | | PE4 |sap+--+CE5| | | | '---' '---' | .---. .---. .---. | | .---. .---. .---. | '-|sap|-|sap|-|sap|-' '-|sap|-|sap|-|sap|-' '-+-' '-+-' '-+-' '-+-' '-+-' '-+-' | | .-+-. .-+-. |CE3| |CE4| '-+-' '-+-' Figure 5: Network Topology with CEs and ACs Refer to Appendix A for an example echoing the topology depicted in Figure 5. Boucadair, et al. Expires 22 September 2022 [Page 7] Internet-Draft A Network YANG for SAPs March 2022 4. Relationship to Other YANG Data Models The SAP network model can be seen as an inventory data associated with SAPs. The model maintains an inventory of nodes contained in a network relying upon [RFC8345]. +-------------------------+ | | | Abstract Network Model | | | +------------+------------+ | +---------+---------+ | | +------V------+ +------V------+ | Abstract | | Inventory | | Network | | Model(s) | | Topology | | e.g., SAP | | Model | | Network | | | | Model | +-----+-------+ +-------------+ | +-----------+-----------+ | | | +----V----+ +----V----+ +----V----+ |TE Topo | |L3 Topo | |L2 Topo | | Model | | Model | | Model | ... +---------+ +---------+ +---------+ Figure 6: Relation of SAP Network Model to Other Models Figure 6 depicts the relationship of the SAP network model to other models. The SAP network model augments the Network model [RFC8345] and imports Network Topology model, while other technology-specific topology models (e.g., Traffic Engineering (TE) Topologies model [RFC8795] or Layer 3 Topologies model [RFC8346]) augment the Network Topology. In the context of Software-Defined Networking (SDN) [RFC7149][RFC7426], the SAP YANG data model can be used to exchange information between control elements, so as to support VPN service provision and resource management discussed in [RFC9182][I-D.ietf-opsawg-l2nm]. Through this data model, the service orchestration layer can learn the available endpoints (i.e., SAPs) of interconnection resources of the underlying network. The service orchestration layer can determine which interconnection endpoints to add to an L2VPN or L3VPN service. With the help of other data models (e.g., L3SM [RFC8299] or L2SM [RFC8466]), Boucadair, et al. Expires 22 September 2022 [Page 8] Internet-Draft A Network YANG for SAPs March 2022 hierarchical control elements can also assess the feasibility of an end-to-end IP connectivity or L2VPN connectivity and, therefore, derive the sequence of domains and the points of interconnection to use. Advanced low-level interface-specific data nodes are not exposed in the SAP model. Filters based on the interface identifiers listed in the SAP model can be used together with dedicated device models to set or get such data. 5. SAP Module Tree Structure The SAP network model 'ietf-sap-ntw' builds on the 'ietf-network' module [RFC8345] by augmenting the nodes with SAPs, which anchor the links and are contained in nodes. The 'sap' attribute defined in the SAP network model is not a tunnel termination point (TTP) (Section 3.6 of [RFC8795]) nor a link, but an abstraction of the termination point defined in [RFC8345]. The structure of the 'ietf-sap-ntw' module is shown in Figure 7. module: ietf-sap-ntw augment /nw:networks/nw:network/nw:network-types: +--rw sap-network! +--rw service-type* identityref augment /nw:networks/nw:network/nw:node: +--rw service* [service-type] +--rw service-type identityref +--rw sap* [sap-id] +--rw sap-id string +--rw description? string +--rw parent-termination-point? nt:tp-id +--rw attachment-interface? string +--rw interface-type? identityref +--rw encapsulation-type? identityref +--rw role? identityref +--rw peer-sap-id? string +--ro sap-status | +--ro status? identityref | +--ro last-change? yang:date-and-time +--ro service-status +--ro status? identityref +--ro last-change? yang:date-and-time Figure 7: SAP YANG Module Tree Structure Boucadair, et al. Expires 22 September 2022 [Page 9] Internet-Draft A Network YANG for SAPs March 2022 A SAP network topology can be used for one or multiple service types ('service-type'). Examples of supported service types are as follows: * L3VPN [RFC4364], * Virtual Private LAN Service (VPLS) [RFC4761][RFC4762], * Virtual Private Wire Service (VPWS) [RFC8214], * BGP MPLS-Based Ethernet VPN [RFC7432], * VPWS in Ethernet VPN [RFC8214], * Provider Backbone Bridging Combined with Ethernet VPN (PBB-EVPN) [RFC7623], * VXLAN-based EVPN [RFC8365], * Virtual Networks [RFC8453], * Enhanced VPN (VPN+) [I-D.ietf-teas-enhanced-vpn], * Network slice [I-D.ietf-teas-ietf-network-slices], * SDWAN [I-D.ietf-bess-bgp-sdwan-usage], and * Basic IP connectivity. These service types build on the types that are already defined in [RFC9181] and additional types that are defined in this document. Other service types can be defined in future YANG modules, if needed. Filters based on the service type can be used to access per-service SAP topology. A example is depicted in Figure 11. A node in the topology can support one or multiple service types ('service-type') among those listed under the 'sap-network' container. A list of SAPs are then bound to each service type that is supported by a given node. Each SAP is characterized as follows: 'sap-id': Includes an identifier that uniquely identifies a SAP within a node. The same SAP may appear under distinct service types. In such a case, the same identifier is used for these service types in association. Boucadair, et al. Expires 22 September 2022 [Page 10] Internet-Draft A Network YANG for SAPs March 2022 SAPs that are associated with the interfaces that are directly hosting services, interfaces that are ready to host per-service sub-interfaces (but not yet activated), or service that are already instantiated on sub-interfaces are listed as SAPs. For example, 'sap-id' may be the VPN network access identifier in Section 7.6 of [RFC9182]. An example to illustrate the use of this attribute during service creation is provided in Appendix D. 'description': Includes a textual description of the SAP. 'parent-termination-point': Includes a reference to the parent interface to which the SAP is bound (e.g., a physical port). This attribute is used, e.g., to associate an interface with its sub-interfaces as all these interfaces may be listed under the SAPs of a node. It is also used to link a SAP with the physical topology. For example, this data node can be used to map the IETF Network Slice endpoints to the service/tunnel/path endpoints in the underlay network as per Section 5.4 of [I-D.ietf-teas-ietf-network-slices]. 'attachment-interface': Indicates a reference to the interface to which the SAP is bound. The same interface may host multiple services. Whether the attachment identifier echoes the content of the attachment interface is deployment specific. For example, this reference may be any of the identifiers ('l2- termination-point', 'local-bridge-reference', 'bearer-reference', or 'lag-interface-id') defined in Section 7.6.1 of [RFC9182] or 'l3-termination-point' defined in Section 7.6.2 of [RFC9182]. It is responsibility of the controller to ensure that consistent references are used in the SAP and underlying device modes or any other device inventory mechanism. 'interface-type': Indicates whether a SAP is bound to a physical port, a loopback interface, a Link Aggregation Group (LAG) interface, an Integrated Routing Bridge (IRB), a local bridge reference, etc. The mapping to the detailed interface types as per [RFC7224] is maintained by the controller. That mapping is used, for example, when the controller translates this SAP network module into device modules. Boucadair, et al. Expires 22 September 2022 [Page 11] Internet-Draft A Network YANG for SAPs March 2022 'encapsulation-type': Indicates the encapsulation type for the interface indicated in the 'attachment-interface' attribute. The types are taken from [RFC9181]. This data node can be used, for example, to decide whether an existing SAP can be (re)used to host a service or if a new sub- interface has to be instantiated. 'role': Specifies the role of a SAP (e.g., a UNI or NNI). A SAP inherits the role of its parent interface ('parent- termination-point'). 'peer-sap-id': Includes a reference to the remote endpoint of an attachment circuit. Examples of such a reference are: a site identifier (Section 6.3 of [RFC8299]), a CE identifier (Section 2.1 of [I-D.ietf-teas-ietf-network-slices]), the IP address of a peer Autonomous System Border Router (ASBR). 'sap-status': Indicates the operational status of a SAP. Values are taken from the values defined in [RFC9181]. When both a sub-interface and its parent interface are present, the status of the parent interface takes precedence over the status indicated for the sub-interface. 'service-status': Reports the operational status of service for a given SAP. This information is particularly useful when many services are enabled for the same SAP, but only a subset of them are activated. 6. SAP YANG Module This module imports types from [RFC8343], [RFC8345], and [RFC9181]. The 'sap-information' is defined as a grouping for the reuse of these nodes in service-specific YANG modules. file "ietf-sap-ntw@2022-02-17.yang" module ietf-sap-ntw { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-sap-ntw"; prefix sap; import ietf-network-topology { Boucadair, et al. Expires 22 September 2022 [Page 12] Internet-Draft A Network YANG for SAPs March 2022 prefix nt; reference "RFC 8345: A YANG Data Model for Network Topologies, Section 6.2"; } import ietf-network { prefix nw; reference "RFC 8345: A YANG Data Model for Network Topologies, Section 6.1"; } import ietf-vpn-common { prefix vpn-common; reference "RFC 9181: A Common YANG Data Model for Layer 2 and Layer 3 VPNs"; } organization "IETF OPSA (Operations and Management Area) Working Group "; contact "WG Web: WG List: Editor: Mohamed Boucadair Author: Oscar Gonzalez de Dios Author: Samier Barguil Author: Qin Wu Author: Victor Lopez "; description "This YANG module defines a model for representing, managing, and controlling the Service Attachment Points (SAPs) in the network topology. Copyright (c) 2022 IETF Trust and the persons identified as authors of the code. All rights reserved. Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to Boucadair, et al. Expires 22 September 2022 [Page 13] Internet-Draft A Network YANG for SAPs March 2022 the license terms contained in, the Revised BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info). This version of this YANG module is part of RFC XXXX (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself for full legal notices."; revision 2022-02-17 { description "Initial version"; reference "RFC XXXX: A Network YANG Model for Service Attachment Points (SAPs)"; } identity virtual-network { base vpn-common:service-type; description "Virtual network."; reference "RFC 8453: Framework for Abstraction and Control of TE Networks (ACTN)"; } identity enhanced-vpn { base vpn-common:service-type; description "Enhanced VPN (VPN+). VPN+ is an approach that is based on existing VPN and Traffic Engineering (TE) technologies but adds characteristics that specific services require over and above traditional VPNs."; reference "draft-ietf-teas-enhanced-vpn: A Framework for Enhanced Virtual Private Network (VPN+) Services"; } identity network-slice { base vpn-common:service-type; description "IETF network slice. An IETF network slice is a logical network topology connecting a number of endpoints using a set of shared or dedicated network resources that are used to satisfy specific service objectives."; reference Boucadair, et al. Expires 22 September 2022 [Page 14] Internet-Draft A Network YANG for SAPs March 2022 "draft-ietf-teas-ietf-network-slices: Framework for IETF Network Slices"; } identity sdwan { base vpn-common:service-type; description "PE-based Software-Defined Wide Area Network (SDWAN)."; reference "draft-ietf-bess-bgp-sdwan-usage: BGP Usage for SDWAN Overlay Network"; } identity basic-connectivity { base vpn-common:service-type; description "Basic IP connectivity. This is, for example, a plain connectivity offered to Enterprises over a dedicated or shared MPLS infrastructure."; } identity interface-role { description "Base identity for the network role of an interface."; } identity uni { base interface-role; description "User-Network Interface (UNI)."; } identity nni { base interface-role; description "Network-to-Network Interface (NNI)."; } identity interface-type { description "Base identity for the interface type."; } identity phy { base interface-type; description "Physical port."; } Boucadair, et al. Expires 22 September 2022 [Page 15] Internet-Draft A Network YANG for SAPs March 2022 identity loopback { base interface-type; description "Loopback interface."; } identity lag { base interface-type; description "Link Aggregation Group (LAG) interface."; } identity irb { base interface-type; description "Integrated Routing Bridge (IRB)."; } identity local-bridge { base interface-type; description "A local bridge reference to accommodate, e.g., implementations that require internal bridging. When such a type is used, a reference to a local bridge domain is used to identify the interface."; } identity logical { base interface-type; description "Refers to a logical sub-interface that is typically used to bind a service. This type is used only if none of the other logical types can be used."; } grouping sap-information { description "Service Attachment Point (SAP) information."; list sap { key "sap-id"; description "The Service Attachment Points are abstraction of the points where network services such as L3VPNs, L2VPNs, or network slices can be attached to."; leaf sap-id { type string; description "Indicates an identifier that uniquely identifies Boucadair, et al. Expires 22 September 2022 [Page 16] Internet-Draft A Network YANG for SAPs March 2022 SAP within a node."; } leaf description { type string; description "A textual description of the SAP."; } leaf parent-termination-point { type nt:tp-id; description "Indicates the parent termination point to which the SAP is attached to. A termination point can be a physical port, an interface, etc."; } leaf attachment-interface { type string; description "Indicates the interface to which the SAP is bound."; } leaf interface-type { type identityref { base interface-type; } description "The type of the interface to which the SAP is bound."; } leaf encapsulation-type { type identityref { base vpn-common:encapsulation-type; } description "Encapsulation type of the interface to which the SAP is bound."; } leaf role { type identityref { base interface-role; } description "Indicates the role of a SAP."; } leaf peer-sap-id { type string; description "Indicates an identifier of the peer's termination identifier (e.g., Customer Edge (CE)). This information can be used for correlation purposes, such as identifying the SAP that is attached to Boucadair, et al. Expires 22 September 2022 [Page 17] Internet-Draft A Network YANG for SAPs March 2022 an endpoint that is provided in a service request."; } container sap-status { config "false"; description "Indicates the SAP status."; uses vpn-common:oper-status-timestamp; } container service-status { config "false"; description "Indicates the service status."; uses vpn-common:oper-status-timestamp; } } } augment "/nw:networks/nw:network/nw:network-types" { description "Introduces a new network type for SAP network."; container sap-network { presence "Indicates SAP Network Type."; description "The presence of the container node indicates the SAP network type."; leaf-list service-type { type identityref { base vpn-common:service-type; } description "Indicates the set of supported service types."; } } } augment "/nw:networks/nw:network/nw:node" { description "Parameters for the SAP level."; list service { key "service-type"; description "A list of supported service type for the node."; leaf service-type { type identityref { base vpn-common:service-type; } description "Indicates a service type."; Boucadair, et al. Expires 22 September 2022 [Page 18] Internet-Draft A Network YANG for SAPs March 2022 } uses sap-information; } } } 7. IANA Considerations This document registers the following namespace URI in the "ns" subregistry within the "IETF XML Registry" [RFC3688]: URI: urn:ietf:params:xml:ns:yang:ietf-sap-ntw Registrant Contact: The IESG. XML: N/A, the requested URI is an XML namespace. This document registers the following YANG module in the YANG Module Names registry [RFC6020] within the "YANG Parameters" registry: name: ietf-sap-ntw namespace: urn:ietf:params:xml:ns:yang:ietf-sap-ntw maintained by IANA? N prefix: sap reference: RFC XXXX 8. Security Considerations The YANG module specified in this document defines schema for data that is designed to be accessed via network management protocols such as NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer is the secure transport layer, and the mandatory-to-implement secure transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer is HTTPS, and the mandatory-to-implement secure transport is TLS [RFC8446]. The Network Configuration Access Control Model (NACM) [RFC8341] provides the means to restrict access for particular NETCONF or RESTCONF users to a preconfigured subset of all available NETCONF or RESTCONF protocol operations and content. There are a number of data nodes defined in this YANG module that are writable/creatable/deletable (i.e., config true, which is the default). These data nodes may be considered sensitive or vulnerable in some network environments. Write operations (e.g., edit-config) to these data nodes without proper protection can have a negative effect on network operations. These are the subtrees and data nodes and their sensitivity/vulnerability: Boucadair, et al. Expires 22 September 2022 [Page 19] Internet-Draft A Network YANG for SAPs March 2022 * /nw:networks/nw:network/nw:node/sap:service-type/sap:sap This subtree specifies the configurations of the nodes in a SAP network model. Unexpected changes to this subtree (e.g., associating a SAP with another parent termination interface) could lead to service disruption and/or network misbehavior. Some of the readable data nodes in this YANG module may be considered sensitive or vulnerable in some network environments. It is thus important to control read access (e.g., via get, get-config, or notification) to these data nodes. These are the subtrees and data nodes and their sensitivity/vulnerability: * /nw:networks/nw:network/nw:node/sap:service-type/sap:sap Unauthorized access to this subtree can disclose the operational state information of the nodes in a SAP network model (e.g., disclose the identity of a customer 'peer-sap-id'). 9. Acknowledgements Thanks to Adrian Farrell and Daniel King for the suggestions on the name used in a previous version. Thanks to Dhruv Dhody, Benoit Claise, Bo Wu, Erez Segev, Raul Arco, and Joe Clarke for the comments. Thanks to Martin Bjoerklund for yang-doctors review. 10. References 10.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004, . [RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010, . Boucadair, et al. Expires 22 September 2022 [Page 20] Internet-Draft A Network YANG for SAPs March 2022 [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., and A. Bierman, Ed., "Network Configuration Protocol (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011, . [RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011, . [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016, . [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, March 2018, . [RFC8345] Clemm, A., Medved, J., Varga, R., Bahadur, N., Ananthakrishnan, H., and X. Liu, "A YANG Data Model for Network Topologies", RFC 8345, DOI 10.17487/RFC8345, March 2018, . [RFC8346] Clemm, A., Medved, J., Varga, R., Liu, X., Ananthakrishnan, H., and N. Bahadur, "A YANG Data Model for Layer 3 Topologies", RFC 8346, DOI 10.17487/RFC8346, March 2018, . [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, . [RFC8795] Liu, X., Bryskin, I., Beeram, V., Saad, T., Shah, H., and O. Gonzalez de Dios, "YANG Data Model for Traffic Engineering (TE) Topologies", RFC 8795, DOI 10.17487/RFC8795, August 2020, . Boucadair, et al. Expires 22 September 2022 [Page 21] Internet-Draft A Network YANG for SAPs March 2022 [RFC9181] Barguil, S., Gonzalez de Dios, O., Ed., Boucadair, M., Ed., and Q. Wu, "A Common YANG Data Model for Layer 2 and Layer 3 VPNs", RFC 9181, DOI 10.17487/RFC9181, February 2022, . 10.2. Informative References [I-D.ietf-bess-bgp-sdwan-usage] Dunbar, L., Guichard, J., Sajassi, A., Drake, J., Najem, B., and D. Carrel, "BGP Usage for SDWAN Overlay Networks", Work in Progress, Internet-Draft, draft-ietf-bess-bgp- sdwan-usage-04, 18 October 2021, . [I-D.ietf-opsawg-l2nm] Barguil, S., Dios, O. G. D., Boucadair, M., and L. A. Munoz, "A Layer 2 VPN Network YANG Model", Work in Progress, Internet-Draft, draft-ietf-opsawg-l2nm-12, 22 November 2021, . [I-D.ietf-teas-enhanced-vpn] Dong, J., Bryant, S., Li, Z., Miyasaka, T., and Y. Lee, "A Framework for Enhanced Virtual Private Network (VPN+) Services", Work in Progress, Internet-Draft, draft-ietf- teas-enhanced-vpn-10, 6 March 2022, . [I-D.ietf-teas-ietf-network-slices] Farrel, A., Drake, J., Rokui, R., Homma, S., Makhijani, K., Contreras, L. M., and J. Tantsura, "Framework for IETF Network Slices", Work in Progress, Internet-Draft, draft- ietf-teas-ietf-network-slices-08, 6 March 2022, . [RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February 2006, . [RFC4761] Kompella, K., Ed. and Y. Rekhter, Ed., "Virtual Private LAN Service (VPLS) Using BGP for Auto-Discovery and Signaling", RFC 4761, DOI 10.17487/RFC4761, January 2007, . Boucadair, et al. Expires 22 September 2022 [Page 22] Internet-Draft A Network YANG for SAPs March 2022 [RFC4762] Lasserre, M., Ed. and V. Kompella, Ed., "Virtual Private LAN Service (VPLS) Using Label Distribution Protocol (LDP) Signaling", RFC 4762, DOI 10.17487/RFC4762, January 2007, . [RFC7149] Boucadair, M. and C. Jacquenet, "Software-Defined Networking: A Perspective from within a Service Provider Environment", RFC 7149, DOI 10.17487/RFC7149, March 2014, . [RFC7224] Bjorklund, M., "IANA Interface Type YANG Module", RFC 7224, DOI 10.17487/RFC7224, May 2014, . [RFC7426] Haleplidis, E., Ed., Pentikousis, K., Ed., Denazis, S., Hadi Salim, J., Meyer, D., and O. Koufopavlou, "Software- Defined Networking (SDN): Layers and Architecture Terminology", RFC 7426, DOI 10.17487/RFC7426, January 2015, . [RFC7432] Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A., Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432, February 2015, . [RFC7623] Sajassi, A., Ed., Salam, S., Bitar, N., Isaac, A., and W. Henderickx, "Provider Backbone Bridging Combined with Ethernet VPN (PBB-EVPN)", RFC 7623, DOI 10.17487/RFC7623, September 2015, . [RFC8214] Boutros, S., Sajassi, A., Salam, S., Drake, J., and J. Rabadan, "Virtual Private Wire Service Support in Ethernet VPN", RFC 8214, DOI 10.17487/RFC8214, August 2017, . [RFC8299] Wu, Q., Ed., Litkowski, S., Tomotaki, L., and K. Ogaki, "YANG Data Model for L3VPN Service Delivery", RFC 8299, DOI 10.17487/RFC8299, January 2018, . [RFC8309] Wu, Q., Liu, W., and A. Farrel, "Service Models Explained", RFC 8309, DOI 10.17487/RFC8309, January 2018, . [RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018, . Boucadair, et al. Expires 22 September 2022 [Page 23] Internet-Draft A Network YANG for SAPs March 2022 [RFC8342] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K., and R. Wilton, "Network Management Datastore Architecture (NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018, . [RFC8343] Bjorklund, M., "A YANG Data Model for Interface Management", RFC 8343, DOI 10.17487/RFC8343, March 2018, . [RFC8365] Sajassi, A., Ed., Drake, J., Ed., Bitar, N., Shekhar, R., Uttaro, J., and W. Henderickx, "A Network Virtualization Overlay Solution Using Ethernet VPN (EVPN)", RFC 8365, DOI 10.17487/RFC8365, March 2018, . [RFC8453] Ceccarelli, D., Ed. and Y. Lee, Ed., "Framework for Abstraction and Control of TE Networks (ACTN)", RFC 8453, DOI 10.17487/RFC8453, August 2018, . [RFC8466] Wen, B., Fioccola, G., Ed., Xie, C., and L. Jalil, "A YANG Data Model for Layer 2 Virtual Private Network (L2VPN) Service Delivery", RFC 8466, DOI 10.17487/RFC8466, October 2018, . [RFC8969] Wu, Q., Ed., Boucadair, M., Ed., Lopez, D., Xie, C., and L. Geng, "A Framework for Automating Service and Network Management with YANG", RFC 8969, DOI 10.17487/RFC8969, January 2021, . [RFC9182] Barguil, S., Gonzalez de Dios, O., Ed., Boucadair, M., Ed., Munoz, L., and A. Aguado, "A YANG Network Data Model for Layer 3 VPNs", RFC 9182, DOI 10.17487/RFC9182, February 2022, . Appendix A. A Simplified SAP Network Example An example of a SAP topology that is reported by a network controller is depicted in Figure 8. This example echoes the topology shown in Figure 5. Only a minimum set of information is provided for each SAP. { "ietf-network:networks": { "network": [ { "network-types": { "service-type": [ Boucadair, et al. Expires 22 September 2022 [Page 24] Internet-Draft A Network YANG for SAPs March 2022 "ietf-vpn-common:l3vpn", "ietf-vpn-common:vpls" ] }, "network-id": "foo:an-id", "node": [ { "node-id": "PE1", "ietf-sap-ntw:service": [ { "service-type": "ietf-vpn-common:l3vpn", "sap": [ { "sap-id": "sap#11", "peer-sap-id": "ce-1", "service-status": { "status": "ietf-vpn-common:op-up" } }, { "sap-id": "sap#12" }, { "sap-id": "sap#13" }, { "sap-id": "sap#14" } ] } ] }, { "node-id": "PE2", "ietf-sap-ntw:service": [ { "service-type": "ietf-vpn-common:l3vpn", "sap": [ { "sap-id": "sap#21" }, { "sap-id": "sap#22", "peer-sap-id": "ce-2", "service-status": { "status": "ietf-vpn-common:op-up" } } Boucadair, et al. Expires 22 September 2022 [Page 25] Internet-Draft A Network YANG for SAPs March 2022 ] } ] }, { "node-id": "PE3", "ietf-sap-ntw:service": [ { "service-type": "ietf-vpn-common:l3vpn", "sap": [ { "sap-id": "sap#31" }, { "sap-id": "sap#32" }, { "sap-id": "sap#33", "peer-sap-id": "ce-3", "service-status": { "status": "ietf-vpn-common:op-up" } } ] } ] }, { "node-id": "PE4", "ietf-sap-ntw:service": [ { "service-type": "ietf-vpn-common:l3vpn", "sap": [ { "sap-id": "sap#41" }, { "sap-id": "sap#42", "peer-sap-id": "ce-4", "service-status": { "status": "ietf-vpn-common:op-up" } }, { "sap-id": "sap#43" }, { "sap-id": "sap#44", Boucadair, et al. Expires 22 September 2022 [Page 26] Internet-Draft A Network YANG for SAPs March 2022 "peer-sap-id": "ce-5", "service-status": { "status": "ietf-vpn-common:op-up" } } ] } ] } ] } ] } } Figure 8: A Simplified SAP Network Example Appendix B. A Simple Example of SAP Network Model: Node Filter In the example shown in Figure 9, PE1 has two physical interfaces "GE0/6/1" and "GE0/6/4". Two sub-interfaces "GE0/6/4.1" and "GE0/6/4.2" are associated with the physical interface "GE0/6/4". Let us consider that four SAPs are exposed to the service orchestrator and mapped to these physical interfaces and sub- interfaces. .-------------------------. | GE0/6/4 | | PE1 .----+----. | |sap#2 |GE0/6/4.1 | | .--+--. | | |sap#3| | | '--+--' | | |GE0/6/4.2 | | .--+--. | | |sap#4| | | '--+--' | | | | +----+----+ | | | GE0/6/1| | .----+----. | |sap#1 | | '----+----' | | '-------------------------' Boucadair, et al. Expires 22 September 2022 [Page 27] Internet-Draft A Network YANG for SAPs March 2022 Figure 9: An Example of a PE and its Physical/Logical Interfaces Let us assume that no service is enabled yet for the SAP associated with the physical interface "GE0/6/1". Also, let us assume that, for the SAPs that are associated with the physical interface "GE0/6/4", VPLS and L3VPN services are activated on the two sub-interfaces "GE0/6/4.1" and "GE0/6/4.2", respectively. A service orchestrator can query what services are provided on which SAPs of PE1 from the network controller by sending, e.g., a GET RESTCONF request. Figure 10 shows the body of the RESTCONF response that is received from the network controller. { "ietf-sap-ntw:service": [ { "service-type": "ietf-vpn-common:l3vpn", "sap": [ { "sap-id": "sap#1", "description": "Ready to host SAPs", "attachment-interface": "GE0/6/1", "interface-type": "ietf-sap-ntw:phy", "role": "ietf-sap-ntw:uni", "sap-status": { "status": "ietf-vpn-common:op-up" } }, { "sap-id": "sap#2", "description": "Ready to host SAPs", "attachment-interface": "GE0/6/4", "interface-type": "ietf-sap-ntw:phy", "role": "ietf-sap-ntw:uni", "sap-status": { "status": "ietf-vpn-common:op-up" } }, { "sap-id": "sap#3", "description": "A first SAP description", "parent-termination-point": "GE0/6/4", "attachment-interface": "GE0/6/4.1", "interface-type": "ietf-sap-ntw:logical", "encapsulation-type": "ietf-vpn-common:vlan-type", "sap-status": { "status": "ietf-vpn-common:op-up" }, Boucadair, et al. Expires 22 September 2022 [Page 28] Internet-Draft A Network YANG for SAPs March 2022 "service-status": { "status": "ietf-vpn-common:op-up" } } ] }, { "service-type": "ietf-vpn-common:vpls", "sap": [ "sap-id": "sap#1", "description": "Ready to host SAPs", "attachment-interface": "GE0/6/1", "interface-type": "ietf-sap-ntw:phy", "role": "ietf-sap-ntw:uni", "sap-status": { "status": "ietf-vpn-common:op-up" } }, { "sap-id": "sap#2", "description": "Ready to host SAPs", "attachment-interface": "GE0/6/4", "interface-type": "ietf-sap-ntw:phy", "role": "ietf-sap-ntw:uni", "sap-status": { "status": "ietf-vpn-common:op-up" } }, { "sap-id": "sap#4", "description": "Another description", "parent-termination-point": "GE0/6/4", "attachment-interface": "GE0/6/4.2", "interface-type": "ietf-sap-ntw:logical", "encapsulation-type": "ietf-vpn-common:vlan-type", "sap-status": { "status": "ietf-vpn-common:op-up" }, "service-status": { "status": "ietf-vpn-common:op-up" } } ] } ] } Boucadair, et al. Expires 22 September 2022 [Page 29] Internet-Draft A Network YANG for SAPs March 2022 Figure 10: An Example of a Response Body to a Request with a Node Filter Figure 11 shows the message body of a response that is received from the network controller if the request includes a filter on the service type for a particular node: Boucadair, et al. Expires 22 September 2022 [Page 30] Internet-Draft A Network YANG for SAPs March 2022 { "ietf-sap-ntw:service": [ { "service-type": "ietf-vpn-common:l3vpn", "sap": [ { "sap-id": "sap#1", "description": "Ready to host SAPs", "attachment-interface": "GE0/6/1", "interface-type": "ietf-sap-ntw:phy", "role": "ietf-sap-ntw:uni", "sap-status": { "status": "ietf-vpn-common:op-up" } }, { "sap-id": "sap#2", "description": "Ready to host SAPs", "attachment-interface": "GE0/6/4", "interface-type": "ietf-sap-ntw:phy", "role": "ietf-sap-ntw:uni", "sap-status": { "status": "ietf-vpn-common:op-up" } }, { "sap-id": "sap#3", "description": "A first SAP description", "parent-termination-point": "GE0/6/4", "attachment-interface": "GE0/6/4.1", "interface-type": "ietf-sap-ntw:logical", "encapsulation-type": "ietf-vpn-common:vlan-type", "sap-status": { "status": "ietf-vpn-common:op-up" }, "service-status": { "status": "ietf-vpn-common:op-up" } } ] } ] } Figure 11: An Example of a Response Body to a Request with a Service Filter Boucadair, et al. Expires 22 September 2022 [Page 31] Internet-Draft A Network YANG for SAPs March 2022 Appendix C. An Example of NNI SAP: Inter-AS VPN Option A Section 10 of [RFC4364] discuses several options to extend a VPN service beyond the scope of a single Autonomous System (AS). For illustration purposes, this section focuses on the so called "Option A" but similar examples can be considered for other options. In this option, an ASBR of an AS is directly connected to an ASBR of a neighboring AS. These two ASBRs are connected by multiple physical or logical interfaces. Also, at least one sub-interface is maintained by these ASBRs for each of the VPNs that require their routes to be passed from one AS to the other AS. Each ASBR behaves as a PE and treats the other as if it were a CE. Figure 12 shows a simplified (excerpt) topology of two ASes A and B with a focus on the interconnection links between these two ASes. .--------------------. .--------------------. | | | | | A .--+--. .--+--. A | | S | +================+ | S | | B | (VRF1)----(VPN1)----(VRF1) | B | | R | | | | R | | | (VRF2)----(VPN2)----(VRF2) | | | a | +================+ | b | | 1 '--+--' '--+--' 1 | | AS A | | AS B | | A .--+--. .--+--. A | | S | +================+ | S | | B | (VRF1)----(VPN1)----(VRF1) | B | | R | | | | R | | | (VRF2)----(VPN2)----(VRF2) | | | a | +================+ | b | | 2 '--+--' '--+--' 2 | | | | | '--------------------' '--------------------' Figure 12: An Example of Inter-AS VPN (Option A) Figure 13 shows an example of a message body that is received from the network controller of AS A (with a focus on the NNIs shown in Figure 12). Boucadair, et al. Expires 22 September 2022 [Page 32] Internet-Draft A Network YANG for SAPs March 2022 { "ietf-network:networks": { "network": [ { "network-types": { "service-type": [ "ietf-vpn-common:l3vpn" ] }, "network-id": "foo:an-id", "node": [ { "node-id": "asbr-a1", "ietf-sap-ntw:service": [ { "service-type": "ietf-vpn-common:l3vpn", "sap": [ { "sap-id": "sap#11", "description": "parent inter-as link#1", "role": "ietf-sap-ntw:nni", "peer-sap-id": "asbr-b1", "service-status": { "status": "ietf-vpn-common:op-up" } }, { "sap-id": "sap#12", "description": "parent inter-as link#2", "role": "ietf-sap-ntw:nni", "peer-sap-id": "asbr-b1", "service-status": { "status": "ietf-vpn-common:op-up" } }, { "sap-id": "sap#13", "description": "vpn1", "role": "ietf-sap-ntw:nni", "peer-sap-id": "asbr-b1", "service-status": { "status": "ietf-vpn-common:op-up" } }, { "sap-id": "sap#14", "description": "vpn2", "role": "ietf-sap-ntw:nni", Boucadair, et al. Expires 22 September 2022 [Page 33] Internet-Draft A Network YANG for SAPs March 2022 "peer-sap-id": "asbr-b1", "service-status": { "status": "ietf-vpn-common:op-up" } } ] } ] }, { "node-id": "asbr-a2", "ietf-sap-ntw:service": [ { "service-type": "ietf-vpn-common:l3vpn", "sap": [ { "sap-id": "sap#11", "description": "parent inter-as link#1", "role": "ietf-sap-ntw:nni", "peer-sap-id": "asbr-b2", "service-status": { "status": "ietf-vpn-common:op-up" } }, { "sap-id": "sap#12", "description": "parent inter-as link#2", "role": "ietf-sap-ntw:nni", "peer-sap-id": "asbr-b2", "service-status": { "status": "ietf-vpn-common:op-up" } }, { "sap-id": "sap#21", "description": "vpn1", "role": "ietf-sap-ntw:nni", "peer-sap-id": "asbr-b2", "service-status": { "status": "ietf-vpn-common:op-up" } }, { "sap-id": "sap#22", "description": "vpn2", "role": "ietf-sap-ntw:nni", "peer-sap-id": "asbr-b2", "service-status": { Boucadair, et al. Expires 22 September 2022 [Page 34] Internet-Draft A Network YANG for SAPs March 2022 "status": "ietf-vpn-common:op-up" } } ] } ] } ] } ] } } Figure 13: An Example of SAP Usage for NNI Appendix D. An Example of Using the SAP Network Model in Service Creation This section describes an example to illustrate the use of the SAP model for service creation purposes. An example of a SAP topology is presented in Figure 8. This example includes four PEs with their SAPs, as well as the customer information. Let us assume that an operator wants to create an L3VPN service between two PEs (PE3 and PE4) that are servicing two CEs (CE6 and CE7). To that aim, the operator would query the SAP topology and would obtain a response similar to what is depicted in Figure 8. That response indicates that the SAPs having "sap#31" and "sap#43" as attachment identifiers do not have any installed services. Once the "free" SAPs are identified, the 'interface-type' and 'encapsulation- type' are checked to see if the requested L3VPN service is compatible with the SAP characteristics. If they are compatible, as proposed in Section 5, the 'attachment-id' value can be used as the VPN network access identifier in an L3NM create query. Let us now assume that, instead of the L3VPN service, the operator wants to set up an L2VPN service. If the 'interface-type' is a physical port, a new logical SAP can be created using the SAP model to cope with the service needs (e.g., the 'encapsulation-type' attribute can be set to 'ietf-vpn-common:vlan-type'). Once the logical SAP is created, the 'attachment-id' of the new SAP is used to create an L2NM instance (Section 7.6 of [I-D.ietf-opsawg-l2nm]). Authors' Addresses Boucadair, et al. Expires 22 September 2022 [Page 35] Internet-Draft A Network YANG for SAPs March 2022 Mohamed Boucadair (editor) Orange France Email: mohamed.boucadair@orange.com Oscar Gonzalez de Dios Telefonica Madrid Spain Email: oscar.gonzalezdedios@telefonica.com Samier Barguil Telefonica Madrid Spain Email: samier.barguilgiraldo.ext@telefonica.com Qin Wu Huawei 101 Software Avenue, Yuhua District Nanjing Jiangsu, 210012 China Email: bill.wu@huawei.com Victor Lopez Nokia Spain Email: victor.lopez@nokia.com Boucadair, et al. Expires 22 September 2022 [Page 36]