YANG Data Models for Bearers and 'Attachment Circuits'-as-a-Service (ACaaS)

YANG Data Models for Bearers and 'Attachment Circuits'-as-a-Service (ACaaS) Orange

mohamed.boucadair@orange.com

Juniper

rroberts@juniper.net

Telefonica

oscar.gonzalezdedios@telefonica.com

Nokia

samier.barguil_giraldo@nokia.com

Huawei Technologies

lana.wubo@huawei.com

Operations and Management OPSAWG Slice Service L3VPN L2VPN Automation Network Automation Orchestration service delivery Service provisioning service segmentation service flexibility service simplification Network Service 3GPP Network Slicing This document specifies a YANG service data model for Attachment Circuits (ACs). This model can be used for the provisioning of ACs before or during service provisioning (e.g., Network Slice Service). The document also specifies a service model for managing bearers over which ACs are established. Also, the document specifies a set of reusable groupings. Whether other service models reuse structures defined in the AC models or simply include an AC reference is a design choice of these service models. Utilizing the AC service model to manage ACs over which a service is delivered has the advantage of decoupling service management from upgrading AC components to incorporate recent AC technologies or features. Discussion Venues Discussion of this document takes place on the Operations and Management Area Working Group Working Group mailing list (opsawg@ietf.org), which is archived at . Source for this draft and an issue tracker can be found at .

Introduction

Scope and Intended Use Connectivity services are provided by networks to customers via dedicated terminating points, such as Service Functions (SFs) , Customer Edges (CEs), peer Autonomous System Border Routers (ASBRs), data centers gateways, or Internet Exchange Points. A connectivity service is basically about ensuring data transfer received from or destined to a given terminating point to or from other terminating points within the same customer/service, an interconnection node, or an ancillary node. The objectives for the connectivity service can be negotiated and agreed upon between the customer and the network provider. To facilitate data transfer within the provider network, it is assumed that the appropriate setup is provisioned over the links that connect customer terminating points and a provider network (usually via a Provider Edge (PE)), allowing successfully data exchanged over these links. The required setup is referred to in this document as Attachment Circuit (AC), while the underlying link is referred to as "bearer". This document adheres to the definition of an Attachment Circuit as provided in "BGP/MPLS IP Virtual Private Networks (VPNs)" (), especially:

Routers can be attached to each other, or to end systems, in a variety of different ways: PPP connections, ATM Virtual Circuits (VCs), Frame Relay VCs, ethernet interfaces, Virtual Local Area Networks (VLANs) on ethernet interfaces, GRE tunnels, Layer 2 Tunneling Protocol (L2TP) tunnels, IPsec tunnels, etc. We will use the term "attachment circuit" to refer generally to some such means of attaching to a router. An attachment circuit may be the sort of connection that is usually thought of as a "data link", or it may be a tunnel of some sort; what matters is that it be possible for two devices to be network layer peers over the attachment circuit.

When a customer requests a new value-added service, the service can be bound to existing attachment circuits or trigger the instantiation of new attachment circuits. The provisioning of a value-added service should, thus, accommodate both deployments. Also, because the instantiation of an attachment circuit requires coordinating the provisioning of endpoints that might not belong to the same administrative entity (customer vs. provider or distinct operational teams within the same provider, etc.), providing programmatic means to expose 'Attachment Circuits'-as-a-Service (ACaaS) greatly simplifies the provisioning of value-added services delivered over an attachment circuit. For example, management systems of adjacent domains that need to connect via an AC will use such means to agree upon the resources that are required for the activation of both sides of an AC (e.g., Layer 2 tags, IP address family, or IP subnets). This document specifies a YANG service data model ("ietf-ac-svc") for managing attachment circuits that are exposed by a network to its customers, such as an enterprise site, an SF, a hosting infrastructure, or a peer network provider. The model can be used for the provisioning of ACs prior or during advanced service provisioning (e.g., IETF Network Slice Service defined in "A Framework for Network Slices in Networks Built from IETF Technologies" ). The "ietf-ac-svc" module () includes a set of reusable groupings. Whether a service model reuses structures defined in the "ietf-ac-svc" or simply includes an AC reference (that was communicated during AC service instantiation) is a design choice of these service models. Relying upon the AC service model to manage ACs over which services are delivered has the merit of decorrelating the management of the (core) service vs. upgrade the AC components to reflect recent AC technologies or new features (e.g., new encryption scheme, additional routing protocol). This document favors the approach of completely relying upon the AC service model instead of duplicating data nodes into specific modules of advanced services that are delivered over an Attachment Circuit. Since the provisioning of an AC requires a bearer to be in place, this document introduces a new module called "ietf-bearer-svc" that enables customers to manage their bearer requests (). The customers can then retrieve a provider-assigned bearer reference that they will include in their AC service requests. Likewise, a customer may retrieve whether their bearers support a synchronization mechanism such as Sync Ethernet (SyncE) . An example of retrieving a bearer reference is provided in . An AC service request can provide a reference to a bearer or a set of peer Service Attachment Points (SAPs) specified in "A YANG Network Data Model for Service Attachment Points (SAPs)" . Both schemes are supported in the AC service model. When several bearers are available, the AC service request may filter them based on the bearer type, synchronization support, etc. Each AC is identified with a unique identifier within a provider domain. From a network provider standpoint, an AC can be bound to a single or multiple SAPs . Likewise, the same SAP can be bound to one or multiple ACs. However, the mapping between an AC and a PE in the provider network that terminates that AC is hidden to the application that makes use of the AC service model. Such mapping information is internal to the network controllers. As such, the details about the (node-specific) attachment interfaces are not exposed in the AC service model. However, these details are exposed at the network model per "A Network YANG Data Model for Attachment Circuits" specification . "A YANG Data Model for Augmenting VPN Service and Network Models with Attachment Circuits" specifies augmentations to the L2VPN Service Model (L2SM) and the L3VPN Service Model (L3SM) to bind LxVPN services to ACs. The AC service model does not make any assumptions about the internal structure or even the nature or the services that will be delivered over an attachment circuit or a set of attachment circuits. Customers do not have access to that network view other than the ACs that they ordered. For example, the AC service model can be used to provision a set of ACs to connect multiple sites (Site1, Site2, ..., SiteX) for customer who also requested VPN services. If the provisioning of these services requires specific configuration on ASBR nodes, such configuration is handled at the network level and is not exposed to the customer at the service level. However, the network controller will have access to such a view as the service points in these ASBRs will be exposed as SAPs with "role" set to "ietf-sap-ntw:nni" . The AC service model can be used in a variety of contexts, such as (but not limited to) those provided in :

Create an AC over an existing bearer .
Request an attachment circuit for a known peer SAP ().
Instantiate multiple attachment circuits over the same bearer ().
Control the precedence over multiple attachment circuits ().
Create Multiple ACs bound to Multiple CEs ().
Bind a slice service to a set of pre-provisioned attachment circuits ().
Connect a Cloud Infrastructure to a service provider network ().
Interconnect provider networks (e.g., or ). Such ACs are identified with a "role" set to "ac-common:nni" or "ac-common:public-nni". See to illustrate the use of the AC model for interconnection/peering.
Manage connectivity for complex containerized or virtualized functions in the cloud ().

The YANG data models in this document conform to the Network Management Datastore Architecture (NMDA) defined in .

Positioning ACaaS vs. Other Data Models The AC model specified in this document is not a network model . As such, the model does not expose details related to specific nodes in the provider's network that terminate an AC (e.g., network node identifiers). The mapping between an AC as seen by a customer and the network implementation of an AC is maintained by the network controllers and is not exposed to the customer. This mapping can be maintained using a variety of network models, such as augmented SAP AC network model . The AC service model is not a device model. A network provider may use a variety of device models (e.g., "A YANG Data Model for Routing Management (NMDA Version)" or "YANG Model for Border Gateway Protocol (BGP-4)" ) to provision an AC service in relevant network nodes.

Why Not Use the L2SM as Reference Data Model for ACaaS? The L2VPN Service Model (L2SM) covers some AC-related considerations. Nevertheless, the L2SM structure is primarily focused on Layer 2 aspects. For example, the L2SM does not cover Layer 3 provisioning, which is required for the typical AC instantiation.

Why Not Use the L3SM as Reference Data Model for ACaaS? Like the L2SM, the L3VPN Service Model (L3SM) addresses certain AC-related aspects. However, the L3SM structure does not sufficiently address Layer 2 provisioning requirements. Additionally, the L3SM is primarily designed for conventional L3VPN deployments and, as such, has some limitations for instantiating ACs in other deployment contexts (e.g., cloud environments). For example, the L3SM does not provide the capability to provision multiple BGP peer groups over the same AC.

Editorial Note (To be removed by RFC Editor) Note to the RFC Editor: This section is to be removed prior to publication. This document contains placeholder values that need to be replaced with finalized values at the time of publication. This note summarizes all of the substitutions that are needed. Please apply the following replacements:

XXXX --> the assigned RFC number for this I-D
2023-11-13 --> the actual date of the publication of this document

Conventions and Definitions 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 when, and only when, they appear in all capitals, as shown here. The meanings of the symbols in the YANG tree diagrams are defined in "YANG Tree Diagrams" . LxSM refers to both the L2SM and the L3SM. LxNM refers to both the L2NM and the L3NM. This document uses the following terms:

Bearer:: A physical or logical link that connects a customer node (or site) to a provider network. A bearer can be a wireless or wired link. One or multiple technologies can be used to build a bearer (e.g., Link Aggregation Group (LAG) ). The bearer type can be specified by a customer.
: The operator allocates a unique bearer reference to identify a bearer within its network (e.g., customer line identifier). Such a reference can be retrieved by a customer and used in subsequent service placement requests to unambiguously identify where a service is to be bound.
: The concept of bearer can be generalized to refer to the required underlying connection for the provisioning of an attachment circuit. One or multiple attachment circuits may be hosted over the same bearer (e.g., multiple VLANs on the same bearer that is provided by a physical link).
Customer Edge (CE):: Equipment that is dedicated to a customer and is connected to one or more PEs via ACs.
: A CE can be a router, a bridge, a switch, etc.
Provider Edge (PE):: Equipment owned and managed by the service provider that can support multiple services for different customers.
: Per "Provider Provisioned Virtual Private Network (VPN) Terminology" (), a PE is a device located at the edge of the service network with the functionality that is needed to interface with the customer.
: A PE is connected to one or more CEs via ACs.
Network controller:: Denotes a functional entity responsible for the management of the service provider network.
Network Function (NF):: Used to refer to the same concept as Service Function (SF) ().
: NF is also used in this document as this term is widely used outside the IETF.
: NF and SF are used interchangeably.
Parent Bearer:: Refers to a bearer (e.g., LAG) that is used to build other bearers. These bearers (called, child bearers) inherit th parent bearer properties.
Parent AC:: Refers to an AC that is used to build other ACs. These ACs (called, child ACs) inherit th parent AC properties.
Service orchestrator:: Refers to a functional entity that interacts with the customer of a network service. The service orchestrator is typically responsible for the attachment circuits, the PE selection, and requesting the activation of the requested service to a network controller.
Service provider network:: A network that is able to provide network services (e.g., Layer 2 VPN, Layer 3 VPN, or Network Slice Services).
Service provider:: A service provider that offers network services (e.g., Layer 2 VPN, Layer 3 VPN, or Network Slice Services).

The names of data nodes are prefixed using the prefix associated with the corresponding imported YANG module as shown in : Modules and Their Associated Prefixes

Prefix	Module	Reference
inet	ietf-inet-types
key-chain	ietf-key-chain
nacm	ietf-netconf-acm
vpn-common	ietf-vpn-common

Relationship to Other AC Data Models depicts the relationship between the various AC data models:

"ietf-ac-common" ()
"ietf-bearer-svc" ()
"ietf-ac-svc" ()
"ietf-ac-ntw" ()
"ietf-ac-glue" ()

AC Data Models ietf-bearer-svc | ^ ^ | | | | | +------------------------ ietf-ac-ntw | ^ | | | | +----------- ietf-ac-glue -----------+ ]]> "ietf-ac-common" is imported by "ietf-bearer-svc", "ietf-ac-svc", and "ietf-ac-ntw". Bearers managed using "ietf-bearer-svc" may be referenced in the service ACs managed using "ietf-ac-svc". Similarly, a bearer managed using "ietf-bearer-svc" may list the set of ACs that use that bearer. In order to ease correlation between an AC service requests and the actual AC provisioned in the network, "ietf-ac-ntw" uses the AC references exposed by "ietf-ac-svc". To bind Layer 2 VPN or Layer 3 VPN services with ACs, "ietf-ac-glue" augments the LxSM and LxNM with AC service references exposed by "ietf-ac-svc" and AC network references exposed bt "ietf-ac-ntw".

Sample Uses of the Data Models

ACs Terminated by One or Multiple Customer Edges (CEs) depicts two target topology flavors that involve ACs. These topologies have the following characteristics:

A CE can be either a physical device or a logical entity. Such logical entity is typically a software component (e.g., a virtual service function that is hosted within the provider's network or a third-party infrastructure). A CE is seen by the network as a peer SAP.
An AC service request may include one or multiple ACs, which may be associated to a single CE or multiple CEs.
CEs may be either dedicated to one single connectivity service or host multiple connectivity services (e.g., CEs with roles of SFs ).
A network provider may bind a single AC to one or multiple peer SAPs (e.g., CE#1 and CE#2 are tagged as peer SAPs for the same AC). For example, and as discussed in , multiple CEs can be attached to a PE over the same attachment circuit. This scenario is typically implemented when the Layer 2 infrastructure between the CE and the network is a multipoint service.
A single CE may terminate multiple ACs, which can be associated with the same bearer or distinct bearers.
Customers may request protection schemes in which the ACs associated with their endpoints are terminated by the same PE (e.g., CE#3), distinct PEs (e.g., CE#34), etc. The network provider uses this request to decide where to terminate the AC in the provider network (i.e., select which PE(s) to use) and also whether to enable specific capabilities (e.g., Virtual Router Redundancy Protocol (VRRP) ). Note that placement constraints may also be requested during the instantiation of the underlying bearers ().

Examples of ACs

Separate AC Provisioning vs. Actual Service Provisioning The procedure to provision a service in a service provider network may depend on the practices adopted by a service provider. This includes the workflow put in place for the provisioning of network services and how they are bound to an attachment circuit. For example, a single attachment circuit may be used to host multiple connectivity services. In order to avoid service interference and redundant information in various locations, a service provider may expose an interface to manage ACs network-wide. Customers can then request a bearer or an attachment circuit to be put in place, and then refer to that bearer or AC when requesting services that are bound to the bearer or AC. specifies augmentations to the L2SM and the L3SM to bind LxVPN services to ACs. shows the positioning of the AC service model in the overall service delivery process.

An Example of AC Model Usage In order to ease the mapping between the service model and underlying network models (e.g., the L3VPN Network Model (L3NM), SAP), the name conventions used in existing network data models are reused as much as possible. For example, "local-address" is used rather than "provider-address" (or similar) to refer to an IP address used in the provider network. This approach is consistent with the automation framework defined in .

Description of the Data Models

The Bearer Service ("ietf-bearer-svc") YANG Module shows the tree for managing the bearers (that is, the properties of an attachment that are below Layer 3). A bearer can be a physical or logical link (e.g., LAG ). Also, a bearer can be a wireless or wired link. A reference to a bearer is generated by the operator. Such a reference can be used, e.g., in a subsequent service request to create an AC. The anchoring of the AC can also be achieved by indicating (with or without a bearer reference), a peer SAP identifier (e.g., an identifier of an SF).

Bearer Service Tree Structure In some deployments, a customer may first retrieve a list of available presence locations before actually placing an order for a bearer creation. The request is filtered based upon a customer name and an Autonomous System Number (ASN). The reserved value "AS 0" is used for customers with no ASN. The retrieved location names may be then referenced in a bearer creation request ("provider-location-reference"). See the example provided in . The same customer site (CE, SF, etc.) can terminate one or multiple bearers; each of them uniquely identified by a reference that is assigned by the network provider. These bearers can terminate on the same or distinct network nodes. CEs that terminate multiple bearers are called multi-homed CEs. A bearer can be created, modified, or discovered from the network. For example, the following deployment options can be considered:

Greenfield creation:: In this scenario, bearers are created from scratch using specific requests made to a network controller. This method allows providers to tailor bearer creation to meet customer-specific needs. For example, a bearer request may indicate some hints about the placement constraints ('placement-constraints'). These constraints are used by a provider to determine how/where to terminate a bearer in the network side (e.g., Point of Presence (PoP) or PE selection).
Auto-discovery using network protocols:: Devices can use specific protocols (e.g., Link Layer Discovery Protocol (LLDP) ) to automatically discover and connect to available network resources. A network controller can use such reported information to expose discovered bearers from the network using the same bearer data model structure.

A request to create a bearer may include a set of constraints ("placement-constraints") that are used by a controller to decide the network terminating side of a bearer (e.g., PE selection, PE redundancy, or PoP selection). Future placement criteria ("constraint-type") may be defined in the future to accommodate specific deployment contexts. The descriptions of the bearer data nodes are as follows:

'name':: Used to uniquely identify a bearer. This name is typically selected by the client when requesting a bearer.
'customer-name':: Indicates the name of the customer who ordered the bearer.
'description':: Includes a textual description of the bearer.
'group':: Tags a bearer with one ore more identifiers that are used to group a set of bearers.
'op-comment':: Includes operational comments that may be useful for managing the bearer (building, level, etc.). No structure is associated with this data node to accommodate all deployments.
'bearer-parent-ref':: Specifies the parent bearer. This data node can be used, e.g., if a bearer is a member of a LAG.
'bearer-lag-member':: Lists the bearers that are members of a LAG. Members can be declared as part of a LAG using 'bearer-parent-ref'.
'sync-phy-capable':: Reports whether a synchronization physical (Sync PHY) mechanism is supported for this bearer.
'sync-phy-enabled':: Indicates whether a Sync PHY mechanism is enabled for a bearer. Only applies when 'sync-phy-capable' is set to 'true'.
'sync-phy-type':: Specifies the Sync PHY mechanism (e.g., SynchE ) enabled for the bearer.
'provider-location-reference':: Indicates a location identified by a provider-assigned reference.
'customer-point':: Specifies the customer terminating point for the bearer. A bearer request can indicate a device, a site, a combination thereof, or a custom information when requesting a bearer. All these schemes are supported in the model.
'type':: Specifies the bearer type (Ethernet, wireless, LAG, etc.).
'test-only':: Indicates that a request is only for test and not for setting, even if there are no errors. This is used for feasibility checks. This data node is applicable only when the data model is used with protocols which do not natively support such option. For example, this data node is redundant with the "test-only" value of the <test-option> parameter in the NETCONF <edit-config> operation ().
'bearer-reference':: Returns an internal reference for the service provider to uniquely identify the bearer. This reference can be used when requesting services. provides an example about how this reference can be retrieved by a customer.
: Whether the 'bearer-reference' mirrors the content of the 'name' is deployment-specific. The module does not assume nor preclude such schemes.
'ac-svc-ref':: Specifies the set of attachment circuits that are bound to the bearer.
'requested-start':: Specifies the requested date and time when the bearer is expected to be active.
'requested-stop':: Specifies the requested date and time when the bearer is expected to be disabled.
'actual-start':: Reports the actual date and time when the bearer actually was enabled.
'actual-stop':: Reports the actual date and time when the bearer actually was disabled.
'status':: Used to track the overall status of a given bearer. Both operational and administrative status are maintained together with a timestamp.
: The "admin-status" attribute is typically configured by a network operator to indicate whether the service is enabled, disabled, or subjected to additional testing or pre-deployment checks. These additional options, such as 'admin-testing' and 'admin-pre-deployment', provide the operators the flexibility to conduct additional validations on the bearer before deploying services over that connection.
'oper-status':: The "oper-status" of a bearer reflects its operational state as observed. As a bearer can contain multiple services, the operational status should only reflect the status of the bearer connection. To obtain network-level service status, specific network models such as those in or should be consulted.
: It is important to note that the "admin-status" attribute should remain independent of the "oper-status". In other words, the setting of the intended administrative state (e.g., whether "admin-up" or "admin-testing") MUST NOT be influenced by the current operational state. If the bearer is administratively set to 'admin-down', it is expected that the bearer will also be operationally 'op-down' as a result of this administrative decision.
: To assess the service delivery status for a given bearer comprehensively, it is recommended to consider both administrative and operational service status values in conjunction. This holistic approach allows a network controller or operator to identify anomalies effectively.
: For instance, when a bearer is administratively enabled but the "operational-status" of that bearer is reported as "op-down", it should be expected that the "oper-status" of services transported over that bearer is also down. These status values differing should trigger the detection of an anomaly condition.
: See "A Common YANG Data Model for Layer 2 and Layer 3 VPNs" for more details.

The Attachment Circuit Service ("ietf-ac-svc") YANG Module The full tree diagram of the module can be generated using, e.g., the "pyang" tool . That tree is not included here because it is too long (). Instead, subtrees are provided for the reader's convenience. The full tree of the 'ac-svc' is provided in .

Overall Structure The overall tree structure of the AC service module is shown in .

Overall AC Service Tree Structure The rationale for deciding whether a reusable grouping should be maintained in this document or be moved into the AC common module is as follows:

Groupings that are reusable among the AC service module, AC network module, other service models, and network models are included in the AC common module.
Groupings that are reusable only by other service models are maintained in the "ietf-ac-svc" module.

Each AC is identified with a unique name ('../ac/name') within a domain. The mapping between this AC and a local PE that terminates the AC is hidden to the application that makes use of the AC service model. This information is internal to the Network controller. As such, the details about the (node-specific) attachment interfaces are not exposed in this service model. The AC service model uses groupings and types defined in the AC common model ('op-instructions', 'dot1q', 'qinq', 'priority-tagged', 'l2-tunnel-service', etc.). Therefore, the description of these nodes are not reiterated in the following subsections. Features are used to tag conditional protions of the model in order to accomodate various deployments (support of layer 2 ACs, Layer 3 ACs, IPv4, IPv6, routing protocols, Bidirectional Forwarding Detection (BFD), etc.).

Service Profiles

Description The 'specific-provisioning-profiles' container () can be used by a service provider to maintain a set of reusable profiles. The profiles definitions are similar to those defined in , including: Quality of Service (QoS), BFD, forwarding, and routing profiles. The exact definition of the profiles is local to each service provider. The model only includes an identifier for these profiles in order to facilitate identifying and binding local policies when building an AC.

Service Profiles As shown in , two profile types can be defined: 'specific-provisioning-profiles' and 'service-provisioning-profiles'. Whether only specific profiles, service profiles, or a combination thereof are used is local to each service provider. The following specific provisioning profiles can be defined:

'encryption-profile-identifier':: Refers to a set of policies related to the encryption setup that can be applied when provisioning an AC.
'qos-profile-identifier':: Refers to a set of policies, such as classification, marking, and actions (e.g., ).
'failure-detection-profile-identifier':: Refers to a set of failure detection policies (e.g., Bidirectional Forwarding Detection (BFD) policies ) that can be invoked when building an AC.
'forwarding-profile-identifier':: Refers to the policies that apply to the forwarding of packets conveyed within an AC. Such policies may consist, for example, of applying Access Control Lists (ACLs).
'routing-profile-identifier':: Refers to a set of routing policies that will be invoked (e.g., BGP policies) when building an AC.

Referencing Service/Specific Profiles All the above mentioned profiles are uniquely identified by the NETCONF/RESTCONF server by an identifier. To ease referencing these profiles by other data models, specific typedefs are defined for each of these profiles. Likewise, an attachment circuit reference typedef is defined when referencing a (global) attachment circuit by its name is required. These typedefs SHOULD be used when other modules need a reference to one of these profiles or attachment circuits.

Attachment Circuits Profiles The 'ac-group-profile' defines reusable parameters for a set of ACs. Each profile is identified by 'name'. Some of the data nodes can be adjusted at the 'ac' level. These adjusted values take precedence over the global values. The structure of 'ac-group-profile' is similar to the one used to model each 'ac' ().

AC Placement Contraints The 'placement-constraints' specifies the placement constraints of an AC. For example, this container can be used to request avoidance of connecting two ACs to the same PE. The full set of supported constraints is defined in (see 'placement-diversity', in particular). The structure of 'placement-constraints' is shown in .

Placement Constraints Subtree Structure

Attachment Circuits The structure of 'attachment-circuits' is shown in .

Attachment Circuits Tree Structure The description of the data nodes is as follows:

'customer-name':: Indicates the name of the customer who ordered the AC or a set of ACs.
'description':: Includes a textual description of the AC.
'test-only':: Indicates that a request is only for test and not for setting, even if there are no errors. This is used for feasibility checks. This data node is applicable only when the data model is used with protocols which do not natively support such option.
'requested-start':: Specifies the requested date and time when the attachment circuit is expected to be active.
'requested-stop':: Specifies the requested date and time when the attachment circuit is expected to be disabled.
'actual-start':: Reports the actual date and time when the attachment circuit actually was enabled.
'actual-stop':: Reports the actual date and time when the attachment circuit actually was disabled.
'role':: Specifies whether an AC is used, e.g., as User-to-Network Interface (UNI) or Network-to-Network Interface (NNI).
'peer-sap-id':: Includes references to the remote endpoints of an attachment circuit . 'peer' is drawn here from the perspective of the provider network. That is, a 'peer-sap' will refer to a customer node.
'ac-group-profile-ref':: Indicates references to one or more profiles that are defined in .
'ac-parent-ref':: Specifies an AC that is inherited by an attachment circuit.
: In contexts where dynamic terminating points are managed for a given AC, a parent AC can be defined with a set of stable and common information, while "child" ACs are defined to track dynamic information. These "child" ACs are bound to the parent AC, which is exposed to services (as a stable reference).
: Whenever a parent AC is deleted, all its "child" ACs MUST be deleted.
: A "child" AC MAY rely upon more than one parent AC (e.g., parent Layer 2 AC and parent Layer 3 AC). In such cases, these ACs MUST NOT be overlapping. An example to illustrate the use of multiple parent ACs is provided in .
'ac-child-ref':: Lists one or more references of child ACs that rely upon this attachment circuit as a parent AC.
'group':: Lists the groups to which an AC belongs . For example, the 'group-id' is used to associate redundancy or protection constraints of ACs. An example is provided in .
'service-ref':: Reports the set of services that are bound to the attachment circuit. The services are indexed by their type.
'server-reference':: Reports the internal reference that is assigned by the provider for this AC. This reference is used to accomodate deployment contexts (e.g., ) where an identifier is generated by the provider to identify a service order locally.
'name':: Associates a name that uniquely identifies an AC within a service provider network.
'service-profile':: References a set of service-specific profiles.
'l2-connection':: See .
'ip-connection':: See .
'routing':: See .
'oam':: See .
'security':: See .
'service':: See .

Layer 2 Connection Structure The 'l2-connection' container () is used to configure the relevant Layer 2 properties of an AC including: encapsulation details and tunnel terminations. For the encapsulation details, the model supports the definition of the type as well as the Identifiers (e.g., VLAN-IDs) of each of the encapsulation-type defined. For the second case, attributes for pseudowire, Virtual Private LAN Service (VPLS), and Virtual eXtensible Local Area Network (VXLAN) tunnel terminations are included. 'bearer-reference' is used to link an AC with a bearer over which the AC is instantiated. This structure relies upon the common groupings defined in .

Layer 2 Connection Tree Structure

IP Connection Structure The 'ip-connection' container is used to configure the relevant IP properties of an AC. The model supports the usage of dynamic and static addressing. This structure relies upon the common groupings defined in . Both IPv4 and IPv6 parameters are supported. shows the structure of the IPv4 connection.

Layer 3 Connection Tree Structure (IPv4) shows the structure of the IPv6 connection.

Layer 3 Connection Tree Structure (IPv6)

Routing As shown in the tree depicted in , the 'routing-protocols' container defines the required parameters to enable the desired routing features for an AC. One or more routing protocols can be associated with an AC. Such routing protocols will be then enabled between a PE and the customer terminating points. Each routing instance is uniquely identified by the combination of the 'id' and 'type' to accommodate scenarios where multiple instances of the same routing protocol have to be configured on the same link. In addition to static routing (), the module supports BGP (), OSPF (), IS-IS (), and RIP (). It also includes a reference to the 'routing-profile-identifier' defined in , so that additional constraints can be applied to a specific instance of each routing protocol. Moreover, the module supports VRRP ().

Routing Tree Structure

Static Routing The static tree structure is shown in .

Static Routing Tree Structure As depicted in , the following data nodes can be defined for a given IP prefix:

'lan-tag':: Indicates a local tag (e.g., "myfavorite-lan") that is used to enforce local policies.
'next-hop':: Indicates the next hop to be used for the static route.
: It can be identified by an IP address, a predefined next-hop type (e.g., 'discard' or 'local-link'), etc.
'metric':: Indicates the metric associated with the static route entry. This metric is used when the route is exported into an IGP.
'failure-detection-profile':: Indicates a failure detection profile (e.g., BFD) that applies for this entry.
'status':: Used to convey the status of a static route entry. This data node can also be used to control the (de)activation of individual static route entries.

BGP The BGP tree structure is shown in .

BGP Tree Structure ../../peer-groups/peer-group/name | | +--rw failure-detection-profile? | | failure-detection-profile-reference | | {vpn-common:bfd}? | +--rw ospf {vpn-common:rtg-ospf}? | | ... | +--rw isis {vpn-common:rtg-isis}? | | ... | +--rw rip {vpn-common:rtg-rip}? | | ... | +--rw vrrp {vpn-common:rtg-vrrp}? | ... ]]> The following data nodes are supported for each BGP 'peer-group':

'name':: Defines a name for the peer group.
'local-as':: Indicates the provider's AS Number (ASN).
'peer-as':: Indicates the customer's ASN.
'address-family':: Indicates the address family of the peer. It can be set to 'ipv4', 'ipv6', or 'dual-stack'.
: This address family might be used together with the service type that uses an AC (e.g., 'vpn-type' ) to derive the appropriate Address Family Identifiers (AFIs) / Subsequent Address Family Identifiers (SAFIs) that will be part of the derived device configurations (e.g., unicast IPv4 MPLS L3VPN (AFI,SAFI = 1,128) as defined in ).
'role':: Specifies the BGP role in a session. Role values are taken from the list defined in .
'local-address':: Specifies a provider's IP address to use when establishing the BGP transport session.
'bgp-max-prefix':: Indicates the maximum number of BGP prefixes allowed in a session for this group.
'authentication':: The module adheres to the recommendations in , as it allows enabling the TCP Authentication Option (TCP-AO) and accommodates the installed base that makes use of MD5. In addition, the module includes a provision for using IPsec.
: Similar to , this version of the ACaaS assumes that parameters specific to the TCP-AO are preconfigured as part of the key chain that is referenced in the ACaaS. No assumption is made about how such a key chain is preconfigured. However, the structure of the key chain should cover data nodes beyond those in "YANG Data Model for Key Chains" , mainly SendID and RecvID ().

For each neighbor, the following data nodes are supported in addition to similar parameters that are provided for a peer group:

'server-reference':: Reports the internal reference that is assigned by the provider for this BGP session.
'remote-address':: Specifies the customer's IP address used to establishing this BGP session.
'requested-start':: Specifies the requested date and time when the BGP session is expected to be active.
'requested-stop':: Specifies the requested date and time when the BGP session is expected to be disabled.
'actual-start':: Reports the actual date and time when the BGP session actually was enabled.
'actual-stop':: Reports the actual date and time when the BGP session actually was disabled.
'status':: Indicates the status of the BGP routing instance.
'peer-group':: Specifies a name of a peer group.
: Parameters that are provided at the 'neighbor' level takes precedence over the ones provided in the peer group.
'failure-detection-profile':: Indicates a failure detection profile (BFD) that applies for a BGP neighbor.

OSPF The OSPF tree structure is shown in .

OSPF Tree Structure The following OSPF data nodes are supported:

'address-family':: Indicates whether IPv4, IPv6, or both address families are to be activated.
'area-id':: Indicates the OSPF Area ID.
'metric':: Associates a metric with OSPF routes.
'sham-links':: Used to create OSPF sham links between two ACs sharing the same area and having a backdoor link ( and ).
'authentication':: Controls the authentication schemes to be enabled for the OSPF instance. The following options are supported: IPsec for OSPFv3 authentication , and the Authentication Trailer for OSPFv2 and OSPFv3 .
'status':: Indicates the status of the OSPF routing instance.

IS-IS The IS-IS tree structure is shown in .

IS-IS Tree Structure The following IS-IS data nodes are supported:

'address-family':: Indicates whether IPv4, IPv6, or both address families are to be activated.
'area-address':: Indicates the IS-IS area address.
'authentication':: Controls the authentication schemes to be enabled for the IS-IS instance. Both the specification of a key chain and the direct specification of key and authentication algorithms are supported.
'status':: Indicates the status of the IS-IS routing instance.

RIP The RIP tree structure is shown in .

RIP Tree Structure 'address-family' indicates whether IPv4, IPv6, or both address families are to be activated. For example, this parameter is used to determine whether RIPv2 , RIP Next Generation (RIPng) , or both are to be enabled.

VRRP The model supports the Virtual Router Redundancy Protocol (VRRP) on an AC ().

VRRP Tree Structure The following data nodes are supported:

'address-family':: Indicates whether IPv4, IPv6, or both address families are to be activated. Note that VRRP version 3 supports both IPv4 and IPv6.
'status':: Indicates the status of the VRRP instance.

Note that no authentication data node is included for VRRP, as there isn't any type of VRRP authentication at this time (see ).

Operations, Administration, and Maintenance (OAM) As shown in the tree depicted in , the 'oam' container defines OAM-related parameters of an AC.

OAM Tree Structure This version of the module supports BFD. The following BFD data nodes can be specified:

'id':: An identifier that uniquely identifies a BFD session.
'local-address':: Indicates the provider's IP address used for a BFD session.
'remote-address':: Indicates the customer's IP address used for a BFD session.
'profile':: Refers to a BFD profile.
'holdtime':: Used to indicate the expected BFD holddown time, in milliseconds.
'status':: Indicates the status of the BFD session.

Security As shown in the tree depicted in , the 'security' container defines a set of AC security parameters.

Security Tree Structure The 'security' container specifies a minimum set of encryption-related parameters that can be requested to be applied to traffic for a given AC. Typically, the model can be used to directly control the encryption to be applied (e.g., Layer 2 or Layer 3 encryption) or invoke a local encryption profile (see ). For example, a service provider may use IPsec when a customer requests Layer 3 encryption for an AC.

Service The structure of the 'service' container is depicted in .

Bandwidth Tree Structure The 'service' container defines the following data nodes:

'mtu':: Specifies the Layer 2 MTU, in bytes, for the AC.
'svc-pe-to-ce-bandwidth' and'svc-ce-to-pe-bandwidth':
'svc-pe-to-ce-bandwidth':: Indicates the inbound bandwidth of the AC (i.e., download bandwidth from the service provider to the customer site).
'svc-ce-to-pe-bandwidth':: Indicates the outbound bandwidth of the AC (i.e., upload bandwidth from the customer site to the service provider).
: Both 'svc-pe-to-ce-bandwidth' and 'svc-ce-to-pe-bandwidth' can be represented using the Committed Information Rate (CIR), the Excess Information Rate (EIR), or the Peak Information Rate (PIR). Both reuse the 'bandwidth-per-type' grouping defined in .
'qos':: Specifies a list of QoS profiles to apply for this AC.
'access-control-list':: Specifies a list of ACL profiles to apply for this AC.

YANG Modules

The Bearer Service ("ietf-bearer-svc") YANG Module This module uses types defined in , , and . file "ietf-bearer-svc@2024-08-06.yang" module ietf-bearer-svc { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-bearer-svc"; prefix bearer-svc; import ietf-inet-types { prefix inet; reference "RFC 6991: Common YANG Data Types, Section 4"; } import ietf-vpn-common { prefix vpn-common; reference "RFC 9181: A Common YANG Data Model for Layer 2 and Layer 3 VPNs"; } import ietf-ac-common { prefix ac-common; reference "RFC CCCC: A Common YANG Data Model for Attachment Circuits"; } import ietf-ac-svc { prefix ac-svc; reference "RFC XXXX: YANG Data Models for Bearers and 'Attachment Circuits'-as-a-Service (ACaaS)"; } organization "IETF OPSAWG (Operations and Management Area Working Group)"; contact "WG Web: WG List: Editor: Mohamed Boucadair Author: Richard Roberts Author: Oscar Gonzalez de Dios Author: Samier Barguil Author: Bo Wu "; description "This YANG module defines a generic YANG model for exposing network bearers as a service. Copyright (c) 2024 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 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 xxx; see the RFC itself for full legal notices."; revision 2024-08-06 { description "Initial revision."; reference "RFC XXXX: YANG Data Models for Bearers and 'Attachment Circuits'-as-a-Service (ACaaS)"; } // Identities identity identification-type { description "Base identity for identification of bearers."; } identity device-id { base identification-type; description "Identification of bearers based on device."; } identity site-id { base identification-type; description "Identification of bearers based on site."; } identity site-and-device-id { base identification-type; description "Identification of bearers based on site and device."; } identity custom { base identification-type; description "Identification of bearers based on other custom criteria."; } identity bearer-type { description "Base identity for bearers type."; } identity ethernet { base bearer-type; description "Ethernet."; } identity wireless { base bearer-type; description "Wireless."; } identity lag { base bearer-type; description "Link Aggregation Group (LAG)."; } identity network-termination-hint { base vpn-common:placement-diversity; description "A hint about the termination at the network side is provided (e.g., geoproximity)."; } identity sync-phy-type { description "Base identity for physical layer synchronization."; } identity sync-e { base sync-phy-type; description "Sync Ethernet (SyncE)."; reference "ITU-T G.781: Synchronization layer functions for frequency synchronization based on the physical layer"; } // Typedef to ease referencing cross-modules typedef bearer-ref { type leafref { path "/bearer-svc:bearers/bearer-svc:bearer/bearer-svc:name"; } description "Defines a type to reference a bearer."; } // Reusable groupings grouping location-information { description "Basic location information."; leaf name { type string; description "Provides a location name. This data node can be mapped, e.g., to the 3GPP NRM IOC ManagedElement."; } leaf address { type string; description "Address (number and street) of the device/site."; } leaf postal-code { type string; description "Postal code of the device/site."; } leaf state { type string; description "State of the device/site. This leaf can also be used to describe a region for a country that does not have states."; } leaf city { type string; description "City of the device/site."; } leaf country-code { type string { pattern '[A-Z]{2}'; } description "Country of the device/site. Expressed as ISO ALPHA-2 code."; } } grouping placement-constraints { description "Constraints related to placement of a bearer."; list constraint { if-feature "vpn-common:placement-diversity"; key "constraint-type"; description "List of constraints."; leaf constraint-type { type identityref { base vpn-common:placement-diversity; } must "not(derived-from-or-self(current(), " + "'vpn-common:bearer-diverse') or " + "derived-from-or-self(current(), " + "'vpn-common:same-bearer'))" { error-message "Only bearer-specific diversity" + "constraints must be provided."; } description "Diversity constraint type for bearers."; } container target { description "The constraint will apply against this list of groups."; choice target-flavor { description "Choice for the group definition."; case id { list group { key "group-id"; description "List of groups."; leaf group-id { type string; description "The constraint will apply against this particular group ID."; } } } case all-bearers { leaf all-other-bearers { type empty; description "The constraint will apply against all other bearers of a site."; } } case all-groups { leaf all-other-groups { type empty; description "The constraint will apply against all other groups managed by the customer."; } } } } } } container locations { description "Retrieves the available provider locations for terminating bearers for a given customer."; list customer { key "name peer-as"; description "List of locations per customer."; leaf name { type string; description "Indicates the name of the customer."; } leaf peer-as { type inet:as-number; description "Indicates the customer's ASN. 0 is used when the customer does not have an ASN."; reference "RFC 7607: Codification of AS 0 Processing"; } list location { key "name"; config false; description "Reports the list of available locations."; uses location-information; } } } container bearers { description "Main container for the bearers."; leaf customer-name { type string; description "Indicates the name of the customer that requested these bearers."; } uses ac-common:op-instructions; container placement-constraints { description "Diversity constraint type."; uses placement-constraints; } list bearer { key "name"; description "Maintains a list of bearers."; leaf name { type string; description "A name that uniquely identifies a bearer for a given customer."; } leaf description { type string; description "A description of this bearer."; } leaf customer-name { type string; description "Indicates the name of the customer that requested this bearer."; } uses vpn-common:vpn-components-group; leaf op-comment { type string; description "Includes comments that can be shared with operational teams and which may be useful for the activation of a bearer. This may include, for example, information about the building, level, etc."; } leaf bearer-parent-ref { type bearer-svc:bearer-ref; description "Specifies the parent bearer. This can be used, e.g., for a Link Aggregation Group (LAG)."; } leaf-list bearer-lag-member { type bearer-svc:bearer-ref; config false; description "Reports LAG members."; } leaf sync-phy-capable { type boolean; config false; description "Indicates when set to true that a mechanism for physical layer synchronization is supported for this bearer. No such mechanism is supported if set to false."; } leaf sync-phy-enabled { type boolean; description "Indicates when set to true that a mechanism for physical layer synchronization is enabled for this bearer. No such mechanism is enabled if set to false."; } leaf sync-phy-type { when "../sync-phy-enabled='true'"; type identityref { base sync-phy-type; } description "Type of the physical layer synchronization."; } leaf provider-location-reference { type string; description "Specifies the provider's location reference."; } container customer-point { description "Base container to link the Bearer existence."; leaf identified-by { type identityref { base identification-type; } description "Specifies how the customer point is identified."; } container device { when "derived-from-or-self(../identified-by, " + "'bearer-svc:device-id') or " + "derived-from-or-self(../identified-by, " + "'bearer-svc:site-and-device-id')" { description "Only applicable if identified-by is device."; } description "Bearer is linked to device."; leaf device-id { type string; description "Identifier for the device where that bearer belongs."; } container location { description "Location of the node."; uses location-information; } } container site { when "derived-from-or-self(../identified-by, " + "'bearer-svc:site-id') or " + "derived-from-or-self(../identified-by, " + "'bearer-svc:site-and-device-id')" { description "Only applicable if identified-by is site."; } description "Bearer is linked to a site."; leaf site-id { type string; description "Identifier for the site or sites where that bearer belongs."; } container location { description "Location of the node."; uses location-information; } } leaf custom-id { when "derived-from-or-self(../identified-by, " + "'bearer-svc:custom')" { description "Only enabled id identified-by is custom."; } type string; description "The semantic of this identifier is shared between the customer/provider using out-of-band means."; } } leaf type { type identityref { base bearer-type; } description "Type of the bearer (e.g., Ethernet or wireless)."; } leaf test-only { type empty; description "When present, this indicates that this is a feasibility check request. No resources are commited for such bearer requests."; } leaf bearer-reference { if-feature "ac-common:server-assigned-reference"; type string; config false; description "This is an internal reference for the service provider to identify the bearers."; } leaf-list ac-svc-ref { type ac-svc:attachment-circuit-reference; config false; description "Specifies the set of ACes that are bound to the bearer."; } uses ac-common:op-instructions; uses ac-common:service-status; } } }

]]>


      
        The AC Service ("ietf-ac-svc") YANG Module
        This module uses types defined in , , , and .
         file "ietf-ac-svc@2024-08-06.yang"
module ietf-ac-svc {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-ac-svc";
  prefix ac-svc;

  import ietf-ac-common {
    prefix ac-common;
    reference
      "RFC CCCC: A Common YANG Data Model for Attachment Circuits";
  }
  import ietf-vpn-common {
    prefix vpn-common;
    reference
      "RFC 9181: A Common YANG Data Model for Layer 2 and Layer 3
                 VPNs";
  }
  import ietf-netconf-acm {
    prefix nacm;
    reference
      "RFC 8341: Network Configuration Access Control Model";
  }
  import ietf-inet-types {
    prefix inet;
    reference
      "RFC 6991: Common YANG Data Types, Section 4";
  }
  import ietf-key-chain {
    prefix key-chain;
    reference
      "RFC 8177: YANG Data Model for Key Chains";
  }

  organization
    "IETF OPSAWG (Operations and Management Area Working Group)";
  contact
    "WG Web:   
     WG List:  

     Editor:   Mohamed Boucadair
               
     Author:   Richard Roberts
               
     Author:   Oscar Gonzalez de Dios
               
     Author:   Samier Barguil
               
     Author:   Bo Wu
               ";
  description
    "This YANG module defines a YANG model for exposing
     attachment circuits as a service (ACaaS).

     Copyright (c) 2024 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 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; see the
     RFC itself for full legal notices.";

  revision 2024-08-06 {
    description
      "Initial revision.";
    reference
      "RFC XXXX: YANG Data Models for Bearers and 'Attachment
                 Circuits'-as-a-Service (ACaaS)";
  }

  /* A set of typedefs to ease referencing cross-modules */

  typedef attachment-circuit-reference {
    type leafref {
      path "/ac-svc:attachment-circuits/ac-svc:ac/ac-svc:name";
    }
    description
      "Defines a reference to an attachment circuit that can be used
       by other modules.";
  }

  typedef ac-group-reference {
    type leafref {
      path "/ac-svc:attachment-circuits/ac-svc:ac-group-profile"
         + "/ac-svc:name";
    }
    description
      "Defines a reference to an attachment circuit profile.";
  }

  typedef encryption-profile-reference {
    type leafref {
      path
        "/ac-svc:specific-provisioning-profiles"
      + "/ac-svc:valid-provider-identifiers"
      + "/ac-svc:encryption-profile-identifier/ac-svc:id";
    }
    description
      "Defines a reference to an encryption profile.";
  }

  typedef qos-profile-reference {
    type leafref {
      path
        "/ac-svc:specific-provisioning-profiles"
      + "/ac-svc:valid-provider-identifiers"
      + "/ac-svc:qos-profile-identifier/ac-svc:id";
    }
    description
      "Defines a reference to a QoS profile.";
  }

  typedef failure-detection-profile-reference {
    type leafref {
      path
        "/ac-svc:specific-provisioning-profiles"
      + "/ac-svc:valid-provider-identifiers"
      + "/ac-svc:failure-detection-profile-identifier"
      + "/ac-svc:id";
    }
    description
      "Defines a reference to a BFD profile.";
  }

  typedef forwarding-profile-reference {
    type leafref {
      path
        "/ac-svc:specific-provisioning-profiles"
      + "/ac-svc:valid-provider-identifiers"
      + "/ac-svc:forwarding-profile-identifier/ac-svc:id";
    }
    description
      "Defines a reference to a forwarding profile.";
  }

  typedef routing-profile-reference {
    type leafref {
      path
        "/ac-svc:specific-provisioning-profiles"
      + "/ac-svc:valid-provider-identifiers"
      + "/ac-svc:routing-profile-identifier/ac-svc:id";
    }
    description
      "Defines a reference to a routing profile.";
  }

  typedef service-profile-reference {
    type leafref {
      path
        "/ac-svc:service-provisioning-profiles"
      + "/ac-svc:service-profile-identifier"
      + "/ac-svc:id";
    }
    description
      "Defines a reference to a service profile.";
  }

  /******************** Reusable groupings ********************/
  // Basic Layer 2 connection

  grouping l2-connection-basic {
    description
      "Defines Layer 2 protocols and parameters that can be
       factorized when provisioning Layer 2 connectivity
       among multiple ACs.";
    container encapsulation {
      description
        "Container for Layer 2 encapsulation.";
      leaf type {
        type identityref {
          base vpn-common:encapsulation-type;
        }
        description
          "Encapsulation type.";
      }
      container dot1q {
        when "derived-from-or-self(../type, 'vpn-common:dot1q')" {
          description
            "Only applies when the type of the tagged interface
             is 'dot1q'.";
        }
        description
          "Tagged interface.";
        uses ac-common:dot1q;
      }
      container qinq {
        when "derived-from-or-self(../type, 'vpn-common:qinq')" {
          description
            "Only applies when the type of the tagged interface
             is 'qinq'.";
        }
        description
          "Includes QinQ parameters.";
        uses ac-common:qinq;
      }
    }
  }

  // Full Layer 2 connection

  grouping l2-connection {
    description
      "Defines Layer 2 protocols and parameters that are used to
       enable AC connectivity.";
    container encapsulation {
      description
        "Container for Layer 2 encapsulation.";
      leaf type {
        type identityref {
          base vpn-common:encapsulation-type;
        }
        description
          "Indicates the encapsulation type.";
      }
      container dot1q {
        when "derived-from-or-self(../type, 'vpn-common:dot1q')" {
          description
            "Only applies when the type of the tagged interface
             is 'dot1q'.";
        }
        description
          "Tagged interface.";
        uses ac-common:dot1q;
      }
      container priority-tagged {
        when "derived-from-or-self(../type, "
           + "'vpn-common:priority-tagged')" {
          description
            "Only applies when the type of the tagged interface is
             'priority-tagged'.";
        }
        description
          "Priority-tagged interface.";
        uses ac-common:priority-tagged;
      }
      container qinq {
        when "derived-from-or-self(../type, 'vpn-common:qinq')" {
          description
            "Only applies when the type of the tagged interface
             is 'qinq'.";
        }
        description
          "Includes QinQ parameters.";
        uses ac-common:qinq;
      }
    }
    choice l2-service {
      description
        "The Layer 2 connectivity service can be provided by
         indicating a pointer to an L2VPN or by specifying a
         Layer 2 tunnel service.";
      container l2-tunnel-service {
        description
          "Defines a Layer 2 tunnel termination.
           It is only applicable when a tunnel is required.";
        uses ac-common:l2-tunnel-service;
      }
      case l2vpn {
        leaf l2vpn-id {
          type vpn-common:vpn-id;
          description
            "Indicates the L2VPN service associated with an
             Integrated Routing and Bridging (IRB) interface.";
        }
      }
    }
    leaf bearer-reference {
      if-feature "ac-common:server-assigned-reference";
      type string;
      description
        "This is an internal reference for the service provider
         to identify the bearer associated with this AC.";
    }
  }

  // Basic IP connection

  grouping ip-connection-basic {
    description
      "Defines basic IP connection parameters.";
    container ipv4 {
      if-feature "vpn-common:ipv4";
      description
        "IPv4-specific parameters.";
      uses ac-common:ipv4-connection-basic;
    }
    container ipv6 {
      if-feature "vpn-common:ipv6";
      description
        "IPv6-specific parameters.";
      uses ac-common:ipv6-connection-basic;
    }
  }

  // Full IP connection

  grouping ip-connection {
    description
      "Defines IP connection parameters.";
    container ipv4 {
      if-feature "vpn-common:ipv4";
      description
        "IPv4-specific parameters.";
      uses ac-common:ipv4-connection {
        augment ac-svc:allocation-type/static-addresses/address {
          leaf failure-detection-profile {
            if-feature "vpn-common:bfd";
            type failure-detection-profile-reference;
            description
              "Points to a failure detection profile.";
          }
          description
            "Adds a failure detection profile.";
        }
      }
    }
    container ipv6 {
      if-feature "vpn-common:ipv6";
      description
        "IPv6-specific parameters.";
      uses ac-common:ipv6-connection {
        augment ac-svc:allocation-type/static-addresses/address {
          leaf failure-detection-profile {
            if-feature "vpn-common:bfd";
            type failure-detection-profile-reference;
            description
              "Points to a failure detection profile.";
          }
          description
            "Adds a failure detection profile.";
        }
      }
    }
  }

  // Routing protocol list

  grouping routing-protocol-list {
    description
      "List of routing protocols used on the AC.";
    leaf type {
      type identityref {
        base vpn-common:routing-protocol-type;
      }
      description
        "Type of routing protocol.";
    }
    list routing-profiles {
      key "id";
      description
        "Routing profiles.";
      leaf id {
        type routing-profile-reference;
        description
          "Reference to the routing profile to be used.";
      }
      leaf type {
        type identityref {
          base vpn-common:ie-type;
        }
        description
          "Import, export, or both.";
      }
    }
  }

  // Static routing with BFD

  grouping ipv4-static-rtg-with-bfd {
    description
      "Configuration specific to IPv4 static routing with
       BFD.";
    list ipv4-lan-prefix {
      if-feature "vpn-common:ipv4";
      key "lan next-hop";
      description
        "List of LAN prefixes for the site.";
      uses ac-common:ipv4-static-rtg-entry;
      leaf failure-detection-profile {
        if-feature "vpn-common:bfd";
        type failure-detection-profile-reference;
        description
          "Points to a failure detection profile.";
      }
      uses ac-common:service-status;
    }
  }

  grouping ipv6-static-rtg-with-bfd {
    description
      "Configuration specific to IPv6 static routing with
       BFD.";
    list ipv6-lan-prefix {
      if-feature "vpn-common:ipv6";
      key "lan next-hop";
      description
        "List of LAN prefixes for the site.";
      uses ac-common:ipv6-static-rtg-entry;
      leaf failure-detection-profile {
        if-feature "vpn-common:bfd";
        type failure-detection-profile-reference;
        description
          "Points to a failure detection profile.";
      }
      uses ac-common:service-status;
    }
  }

  //  BGP Service 

  grouping bgp-neighbor-without-name {
    description
      "A grouping with generic parameters for configuring a BGP 
       neighbor.";
    leaf remote-address {
      type inet:ip-address;
      description
        "The remote IP address of this entry's BGP peer. This is
         a customer IP address.

         If this leaf is not present, this means that the primary
         customer IP address is used as remote IP address.";
    }
    leaf local-address {
      type inet:ip-address;
      description
        "The provider's IP address that will be used to establish
         the BGP session.";
    }
    uses ac-common:bgp-peer-group-without-name;
    container bgp-max-prefix {
      description
        "A container for the maximum number of BGP prefixes
         allowed in the BGP session.";
      leaf max-prefix {
        type uint32;
        description
          "Indicates the maximum number of BGP prefixes allowed
           in the BGP session.

           It allows control of how many prefixes can be received
           from a neighbor.";
        reference
          "RFC 4271: A Border Gateway Protocol 4 (BGP-4),
                     Section 8.2.2";
      }
    }
    uses ac-common:bgp-authentication;
    uses ac-common:op-instructions;
    uses ac-common:service-status;
  }

  grouping bgp-neighbor-with-name {
    description
      "A grouping with generic parameters for configuring a BGP 
       neighbor with an identifier.";
    leaf id {
      type string;
      description
        "A neighbor identifier.";
    }
    uses ac-svc:bgp-neighbor-without-name;
  }

  grouping bgp-neighbor-with-server-reference {
    description
      "A grouping with generic parameters for configuring a BGP 
       neighbor with a reference generated by the provider.";
    leaf server-reference {
      if-feature "ac-common:server-assigned-reference";
      type string;
      config false;
      description
        "This is an internal reference for the service provider
         to identify the BGP session.";
    }
    uses ac-svc:bgp-neighbor-without-name;
  }

  grouping bgp-neighbor-with-name-server-reference {
    description
      "A grouping with generic parameters for configuring a BGP 
       neighbor with an identifier and a reference generated by 
       the provider.";
    leaf id {
      type string;
      description
        "A neighbor identifier.";
    }
    uses ac-svc:bgp-neighbor-with-server-reference;
  }

  grouping bgp-svc {
    description
      "Configuration specific to BGP.";
    container peer-groups {
      description
        "Configuration for BGP peer-groups";
      list peer-group {
        key "name";
        description
          "List of BGP peer-groups configured on the local 
           system - uniquely identified by peer-group
           name.";
        uses ac-common:bgp-peer-group-with-name;
        leaf local-address {
          type inet:ip-address;
          description
            "The provider's local IP address that will be used to
             establish the BGP session.";
        }
        container bgp-max-prefix {
          description
            "A container for the maximum number of BGP prefixes
             allowed in the BGP session.";
          leaf max-prefix {
            type uint32;
            description
              "Indicates the maximum number of BGP prefixes allowed
               in the BGP session.

               It allows control of how many prefixes can be received
               from a neighbor.";
            reference
              "RFC 4271: A Border Gateway Protocol 4 (BGP-4),
                         Section 8.2.2";
          }
        }
        uses ac-common:bgp-authentication;
      }
    }
    list neighbor {
      key "id";
      description
        "List of BGP neighbors.";
      uses ac-svc:bgp-neighbor-with-name-server-reference;
      leaf peer-group {
        type leafref {
          path "../../peer-groups/peer-group/name";
        }
        description
          "The peer-group with which this neighbor is associated.";
      }
      leaf failure-detection-profile {
        if-feature "vpn-common:bfd";
        type failure-detection-profile-reference;
        description
          "Points to a failure detection profile.";
      }
    }
  }

  //  OSPF Service 

  grouping ospf-svc {
    description
      "Service configuration specific to OSPF.";
    uses ac-common:ospf-basic;
    uses ac-common:ospf-authentication;
    uses ac-common:service-status;
  }

  //  IS-IS Service 

  grouping isis-svc {
    description
      "Service configuration specific to IS-IS.";
    uses ac-common:isis-basic;
    uses ac-common:isis-authentication;
    uses ac-common:service-status;
  }

  //  RIP Service 

  grouping rip-svc {
    description
      "Service configuration specific to RIP routing.";
    leaf address-family {
      type identityref {
        base vpn-common:address-family;
      }
      description
        "Indicates whether IPv4, IPv6, or both address families
         are to be activated.";
    }
    uses ac-common:rip-authentication;
    uses ac-common:service-status;
  }

  //  VRRP Service 

  grouping vrrp-svc {
    description
      "Service configuration specific to VRRP.";
    reference
      "RFC 9568: Virtual Router Redundancy Protocol (VRRP)
                 Version 3 for IPv4 and IPv6";
    leaf address-family {
      type identityref {
        base vpn-common:address-family;
      }
      description
        "Indicates whether IPv4, IPv6, or both
         address families are to be enabled.";
    }
    uses ac-common:service-status;
  }

  // Basic routing parameters

  grouping routing-basic {
    description
      "Defines basic parameters for routing protocols.";
    list routing-protocol {
      key "id";
      description
        "List of routing protocols used on the AC.";
      leaf id {
        type string;
        description
          "Unique identifier for the routing protocol.";
      }
      uses routing-protocol-list;
      container bgp {
        when
          "derived-from-or-self(../type, 'vpn-common:bgp-routing')" {
          description
            "Only applies when the protocol is BGP.";
        }
        if-feature "vpn-common:rtg-bgp";
        description
          "Configuration specific to BGP.";
        container peer-groups {
          description
            "Configuration for BGP peer-groups";
          list peer-group {
            key "name";
            description
              "List of BGP peer-groups configured on the local
               system - uniquely identified by peer-group
               name.";
            uses ac-common:bgp-peer-group-with-name;
          }
        }
      }
      container ospf {
        when "derived-from-or-self(../type, "
           + "'vpn-common:ospf-routing')" {
          description
            "Only applies when the protocol is OSPF.";
        }
        if-feature "vpn-common:rtg-ospf";
        description
          "Configuration specific to OSPF.";
        uses ac-common:ospf-basic;
      }
      container isis {
        when "derived-from-or-self(../type, "
           + "'vpn-common:isis-routing')" {
          description
            "Only applies when the protocol is IS-IS.";
        }
       if-feature "vpn-common:rtg-isis";
        description
          "Configuration specific to IS-IS.";
        uses ac-common:isis-basic;
      }
      container rip {
        when "derived-from-or-self(../type, "
           + "'vpn-common:rip-routing')" {
          description
            "Only applies when the protocol is RIP.
             For IPv4, the model assumes that RIP
             version 2 is used.";
        }
        if-feature "vpn-common:rtg-rip";
        description
          "Configuration specific to RIP routing.";
        leaf address-family {
          type identityref {
            base vpn-common:address-family;
          }
          description
            "Indicates whether IPv4, IPv6, or both
             address families are to be activated.";
        }
      }
      container vrrp {
        when "derived-from-or-self(../type, "
           + "'vpn-common:vrrp-routing')" {
          description
            "Only applies when the protocol is the
             Virtual Router Redundancy Protocol (VRRP).";
        }
        if-feature "vpn-common:rtg-vrrp";
        description
          "Configuration specific to VRRP.";
        leaf address-family {
          type identityref {
            base vpn-common:address-family;
          }
          description
            "Indicates whether IPv4, IPv6, or both address families
             are to be enabled.";
        }
      }
    }
  }

  // Full routing parameters

  grouping routing {
    description
      "Defines routing protocols.";
    list routing-protocol {
      key "id";
      description
        "List of routing protocols used on the AC.";
      leaf id {
        type string;
        description
          "Unique identifier for the routing protocol.";
      }
      uses routing-protocol-list;
      container static {
        when "derived-from-or-self(../type, "
           + "'vpn-common:static-routing')" {
          description
            "Only applies when the protocol is static routing
             protocol.";
        }
        description
          "Configuration specific to static routing.";
        container cascaded-lan-prefixes {
          description
            "LAN prefixes from the customer.";
          uses ipv4-static-rtg-with-bfd;
          uses ipv6-static-rtg-with-bfd;
        }
      }
      container bgp {
        when "derived-from-or-self(../type, "
           + "'vpn-common:bgp-routing')" {
          description
            "Only applies when the protocol is BGP.";
        }
        if-feature "vpn-common:rtg-bgp";
        description
          "Configuration specific to BGP.";
        uses bgp-svc;
      }
      container ospf {
        when "derived-from-or-self(../type, "
           + "'vpn-common:ospf-routing')" {
          description
            "Only applies when the protocol is OSPF.";
        }
        if-feature "vpn-common:rtg-ospf";
        description
          "Configuration specific to OSPF.";
        uses ospf-svc;
      }
      container isis {
        when "derived-from-or-self(../type, "
           + "'vpn-common:isis-routing')" {
          description
            "Only applies when the protocol is IS-IS.";
        }
        if-feature "vpn-common:rtg-isis";
        description
          "Configuration specific to IS-IS.";
        uses isis-svc;
      }
      container rip {
        when "derived-from-or-self(../type, "
           + "'vpn-common:rip-routing')" {
          description
            "Only applies when the protocol is RIP.
             For IPv4, the model assumes that RIP version 2 is
             used.";
        }
        if-feature "vpn-common:rtg-rip";
        description
          "Configuration specific to RIP routing.";
        uses rip-svc;
      }
      container vrrp {
        when "derived-from-or-self(../type, "
           + "'vpn-common:vrrp-routing')" {
          description
            "Only applies when the protocol is the Virtual Router
             Redundancy Protocol (VRRP).";
        }
        if-feature "vpn-common:rtg-vrrp";
        description
          "Configuration specific to VRRP.";
        uses vrrp-svc;
      }
    }
  }

  // Encryption choice

  grouping encryption-choice {
    description
      "Container for the encryption profile.";
    choice profile {
      description
        "Choice for the encryption profile.";
      case provider-profile {
        leaf provider-profile {
          type encryption-profile-reference;
          description
            "Reference to a provider encryption profile.";
        }
      }
      case customer-profile {
        leaf customer-key-chain {
          type key-chain:key-chain-ref;
          description
            "Customer-supplied key chain.";
        }
      }
    }
  }

  // Basic security parameters

  grouping ac-security-basic {
    description
      "AC-specific security parameters.";
    container encryption {
      if-feature "vpn-common:encryption";
      description
        "Container for AC security encryption.";
      leaf enabled {
        type boolean;
        description
          "If set to 'true', traffic encryption on the connection
           is required.  Otherwise, it is disabled.";
      }
      leaf layer {
        when "../enabled = 'true'" {
          description
            "Included only when encryption is enabled.";
        }
        type enumeration {
          enum layer2 {
            description
              "Encryption occurs at Layer 2.";
          }
          enum layer3 {
            description
              "Encryption occurs at Layer 3.
               For example, IPsec may be used when a customer 
               requests Layer 3 encryption.";
          }
        }
        description
          "Indicates the layer on which encryption is applied.";
      }
    }
    container encryption-profile {
      when "../encryption/enabled = 'true'" {
        description
          "Indicates the layer on which encryption is enabled.";
      }
      description
        "Container for the encryption profile.";
      uses encryption-choice;
    }
  }

  // Bandwith parameters

  grouping bandwidth {
    description
      "Container for bandwidth.";
    container svc-pe-to-ce-bandwidth {
      if-feature "vpn-common:inbound-bw";
      description
        "From the customer site's perspective, the inbound
         bandwidth of the AC or download bandwidth from the
         service provider to the site.";
      uses ac-common:bandwidth-per-type;
    }
    container svc-ce-to-pe-bandwidth {
      if-feature "vpn-common:outbound-bw";
      description
        "From the customer site's perspective, the outbound
         bandwidth of the AC or upload bandwidth from
         the CE to the PE.";
      uses ac-common:bandwidth-per-type;
    }
  }

  // Basic AC parameters

  grouping ac-basic {
    description
      "Grouping for basic parameters for an attachment circuit.";
    leaf name {
      type string;
      description
        "A name that uniquely identifies the AC.";
    }
    container l2-connection {
      if-feature "ac-common:layer2-ac";
      description
        "Defines Layer 2 protocols and parameters that are required 
         to enable AC connectivity.";
      uses l2-connection-basic;
    }
    container ip-connection {
      if-feature "ac-common:layer3-ac";
      description
        "Defines IP connection parameters.";
      uses ip-connection-basic;
    }
    container routing-protocols {
      description
        "Defines routing protocols.";
      uses routing-basic;
    }
    container oam {
      description
        "Defines the Operations, Administration, and Maintenance
         (OAM) mechanisms used.";
      container bfd {
        if-feature "vpn-common:bfd";
        description
          "Container for BFD.";
        uses ac-common:bfd;
      }
    }
    container security {
      description
        "AC-specific security parameters.";
      uses ac-security-basic;
    }
    container service {
      description
        "AC-specific bandwith parameters.";
      leaf mtu {
        type uint32;
        units "bytes";
        description
          "Layer 2 MTU.";
      }
      uses bandwidth;
    }
  }


  // Full AC parameters

  grouping ac {
    description
      "Grouping for an attachment circuit.";
    leaf name {
      type string;
      description
        "A name of the AC. Data models that need to reference  
         an attachment circuit should use 
         attachment-circuit-reference.";
    }
    leaf-list service-profile {
      type service-profile-reference;
      description
        "A reference to a service profile.";
    }
    container l2-connection {
      if-feature "ac-common:layer2-ac";
      description
        "Defines Layer 2 protocols and parameters that are required 
         to enable AC connectivity.";
      uses l2-connection;
    }
    container ip-connection {
      if-feature "ac-common:layer3-ac";
      description
        "Defines IP connection parameters.";
      uses ip-connection;
    }
    container routing-protocols {
      description
        "Defines routing protocols.";
      uses routing;
    }
    container oam {
      description
        "Defines the OAM mechanisms used.";
      container bfd {
        if-feature "vpn-common:bfd";
        description
          "Container for BFD.";
        list session {
          key "id";
          description
            "List of BFD sessions.";
          leaf id {
             type string;
             description
               "A unique identifer for the BFD session.";
          }
          leaf local-address {
            type inet:ip-address;
            description
              "Provider's IP address of the BFD session.";
          }
          leaf remote-address {
            type inet:ip-address;
            description
              "Customer's IP address of the BFD session.";
          }
          leaf profile {
            type failure-detection-profile-reference;
            description
              "Points to a BFD profile.";
          }
          uses ac-common:bfd;
          uses ac-common:service-status;
        } 
      }
    }
    container security {
      description
        "AC-specific security parameters.";
      uses ac-security-basic;
    }
    container service {
      description
        "AC-specific bandwith parameters.";
      leaf mtu {
        type uint32;
        units "bytes";
        description
          "Layer 2 MTU.";
      }
      uses bandwidth;
      container qos {
        if-feature "vpn-common:qos";
        description
          "QoS configuration.";
        container qos-profiles {
          description
            "QoS profile configuration.";
          list qos-profile {
            key "profile";
            description
              "Points to a QoS profile.";
            leaf profile {
              type qos-profile-reference;
              description
                "QoS profile to be used.";
            }
            leaf direction {
              type identityref {
                base vpn-common:qos-profile-direction;
              }
              description
                "The direction to which the QoS profile
                 is applied.";
            }
          }
        }
      }
      container access-control-list {
        description
          "Container for the Access Control List (ACL).";
        container acl-profiles {
          description
            "ACL profile configuration.";
          list acl-profile {
            key "profile";
            description
              "Points to an ACL profile.";
            leaf profile {
              type forwarding-profile-reference;
              description
                "Forwarding profile to be used.";
            }
          }
        }
      }
    }
  }

  // Parent and Child ACs

  grouping ac-hierarchy {
    description
      "Container for parent and child AC references.";
    leaf-list ac-parent-ref {
      type ac-svc:attachment-circuit-reference;
      description
        "Specifies a parent AC that is inherited by an AC.
         In contexts where dynamic terminating points are 
         bound to the same AC, a parent AC with stable
         information is created with a set of child ACs
         to track dynamic AC information.";
    }
    leaf-list ac-child-ref {
      type ac-svc:attachment-circuit-reference;
      config false;
      description
        "Specifies a child AC that relies upon a parent AC.";
    }
  }

  /******************** Main AC containers ********************/

  container specific-provisioning-profiles {
    description
      "Contains a set of valid profiles to reference for an AC.";
    uses ac-common:ac-profile-cfg;
  }
  container service-provisioning-profiles {
    description
      "Contains a set of valid profiles to reference for an AC.";
    list service-profile-identifier {
      key "id";
      description
        "List of generic service profile identifiers.";
      leaf id {
        type string;
        description
          "Identification of the service profile to be used.
           The profile only has significance within the service
           provider's administrative domain.";
      }
    }
    nacm:default-deny-write;
  }
  container attachment-circuits {
    description
      "Main container for the attachment circuits.";
    list ac-group-profile {
      key "name";
      description
        "Maintains a list of profiles that are shared among
         a set of ACs.";
      uses ac;
    }
    container placement-constraints {
      description
        "Diversity constraint type.";
      uses vpn-common:placement-constraints;
    }
    leaf customer-name {
      type string;
      description
        "Indicates the name of the customer that requested these
         ACs.";
    }
    uses ac-common:op-instructions;
    list ac {
      key "name";
      description
        "Global provisioning of attachment circuits.";
      leaf customer-name {
        type string;
        description
          "Indicates the name of the customer that requested this
           AC.";
      }
      leaf description {
        type string;
        description
          "Associates a description with an AC.";
      }
      leaf test-only {
        type empty;
        description
         "When present, this indicates that this is a feasibility
          check request. No resources are commited for such AC 
          requests.";
      }
      uses ac-common:op-instructions;
      leaf role {
        type identityref {
          base ac-common:role;
        }
        description
          "Indicates whether this AC is used as UNI, NNI, etc.";
      }
      leaf-list peer-sap-id {
        type string;
        description
          "One or more peer SAPs can be indicated.";
      }
      leaf-list ac-group-profile-ref {
        type ac-group-reference;
        description
          "A reference to an AC profile.";
      }
      uses ac-hierarchy;
      uses ac-common:redundancy-group;
      list service-ref {
        key "service-type service-id";
        config false;
        description
          "Reports the set of services that are bound to the AC.";
        leaf service-type {
          type identityref {
            base vpn-common:service-type;
          }
          description
            "Indicates the service type (e.g., L3VPN or Network Slice
             Service).";
          reference
            "RFC 9408: A YANG Network Data Model for Service 
                       Attachment Points (SAPs), Section 5";
        }
        leaf service-id {
          type string;
          description
            "Indicates an identifier of a service instance
             of a given type that uses the AC.";
        }
      }
      leaf server-reference {
        if-feature "ac-common:server-assigned-reference";
        type string;
        config false;
        description
          "Reports an internal reference for the service provider
           to identify the AC.";
      }
      uses ac;
    }
  }
}

]]>


    
      Security Considerations
      This section uses the template described in Section 3.7 of .
      The YANG modules specified in this document define schema for data
   that is designed to be accessed via network management protocols such
   as NETCONF  or RESTCONF .  The lowest NETCONF layer
   is the secure transport layer, and the mandatory-to-implement secure
   transport is Secure Shell (SSH) .  The lowest RESTCONF layer
   is HTTPS, and the mandatory-to-implement secure transport is TLS
   .
      The Network Configuration Access Control Model (NACM) 
   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 these YANG modules 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)
   and delete operations to these data nodes without proper protection
   or authentication can have a negative effect on network operations.
   Specifically, the following subtrees and data nodes have particular
sensitivities/vulnerabilities in the "ietf-bearer-svc" module:
      
        'placement-constraints':
        
          An attacker who is able to access this data node can modify the
   attributes to influence how a service is delivered to a customer, and
   this leads to Service Level Agreement (SLA) violations.
        
        'bearer':
        
          An attacker who is able to access this data node can modify
   the attributes of bearer and, thus, hinder how ACs are built.
        
        
        

          In addition, an attacker could attempt to add a new bearer or
   delete existing ones. An attacker may also change the requested
   type, whether it is for test-only, or the activation scheduling.
        
      
      The following subtrees and data nodes have particular
sensitivities/vulnerabilities in the "ietf-ac-svc" module:
      
        'specific-provisioning-profiles':
        
          This container includes a set of sensitive data that influence
 how an AC will be delivered. For example, an attacker who has access
 to these data nodes may be able to manipulate routing policies, QoS
 policies, or encryption properties.
        
        
        

          These profiles are defined with "nacm:default-deny-write"
 tagging .
        
        'service-provisioning-profiles':
        
          An attacker who has access to these data nodes may be able
   to manipulate service-specific policies to be applied for an AC.
        
        
        

          This container is defined with "nacm:default-deny-write" tagging.
        
        'ac':
        
          An attacker who is able to access this data node can modify
   the attributes of an AC (e.g., QoS, bandwidth, routing protocols,
   keying material), leading to malfunctioning of services that will
   be delivered over that AC and therefore to SLA violations.
   In addition, an attacker could attempt to add a new AC.
        
      
      Some of the readable data nodes in these YANG modules 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. Specifically, the following subtrees and data nodes have particular
sensitivities/vulnerabilities in the "ietf-bearer-svc" module:
      
        'customer-point' and 'locations':
        
          An attacker can retrieve privacy-related information about locations from where
 the customer is connected or can be serviced. Disclosing such information may be used to infer
 the identity of the customer.
        
      
      The following subtrees and data nodes have particular
sensitivities/vulnerabilities in the "ietf-ac-svc" module:
      
        'customer-name', 'l2-connection', and 'ip-connection':
        
          An attacker can retrieve privacy-related information, which can be used to track a
 customer.  Disclosing such information may be considered a
 violation of the customer-provider trust relationship.
        
        'keying-material':
        
          An attacker can retrieve the cryptographic keys
 protecting the underlying connectivity services (routing, in
 particular).  These keys could be used to inject spoofed routing
 advertisements.
        
      
      Several data nodes ('bgp', 'ospf', 'isis', and 'rip') rely
   upon  for authentication purposes.  As such, the AC service module
   inherits the security considerations discussed in Section 5 of
   .  Also, these data nodes support supplying explicit keys as
   strings in ASCII format.  The use of keys in hexadecimal string
   format would afford greater key entropy with the same number of
   key-string octets.  However, such a format is not included in this
   version of the AC service model because it is not supported by the underlying
   device modules (e.g., ).
    
    
      IANA Considerations
      IANA is requested to register the following URIs in the "ns" subregistry within
   the "IETF XML Registry" :
      
      IANA is requested to register the following YANG modules in the "YANG Module
   Names" subregistry  within the "YANG Parameters" registry.


  
    
      References
      
        Normative References
        
          
            BGP/MPLS IP Virtual Private Networks (VPNs)
            
            
            
            
              This document describes a method by which a Service Provider may use an IP backbone to provide IP Virtual Private Networks (VPNs) for its customers. This method uses a "peer model", in which the customers' edge routers (CE routers) send their routes to the Service Provider's edge routers (PE routers); there is no "overlay" visible to the customer's routing algorithm, and CE routers at different sites do not peer with each other. Data packets are tunneled through the backbone, so that the core routers do not need to know the VPN routes. [STANDARDS-TRACK]
            
          
          
          
        
        
          
            A YANG Network Data Model for Service Attachment Points (SAPs)
            
            
            
            
            
            
            
              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 defined in RFC 8345 by adding the concept of Service Attachment Points (SAPs). The SAPs 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. One or multiple services can be bound to the same SAP. Both User-to-Network Interface (UNI) and Network-to-Network Interface (NNI) are supported in the SAP data model.
            
          
          
          
        
        
          
            Network Management Datastore Architecture (NMDA)
            
            
            
            
            
            
            
              Datastores are a fundamental concept binding the data models written in the YANG data modeling language to network management protocols such as the Network Configuration Protocol (NETCONF) and RESTCONF. This document defines an architectural framework for datastores based on the experience gained with the initial simpler model, addressing requirements that were not well supported in the initial model. This document updates RFC 7950.
            
          
          
          
        
        
          
            Key words for use in RFCs to Indicate Requirement Levels
            
            
            
              In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.
            
          
          
          
          
        
        
          
            Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words
            
            
            
              RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings.
            
          
          
          
          
        
        
          
            Common YANG Data Types
            
            
            
              This document introduces a collection of common data types to be used with the YANG data modeling language. This document obsoletes RFC 6021.
            
          
          
          
        
        
          
            YANG Data Model for Key Chains
            
            
            
            
            
            
            
              This document describes the key chain YANG data model. Key chains are commonly used for routing protocol authentication and other applications requiring symmetric keys. A key chain is a list containing one or more elements containing a Key ID, key string, send/accept lifetimes, and the associated authentication or encryption algorithm. By properly overlapping the send and accept lifetimes of multiple key chain elements, key strings and algorithms may be gracefully updated. By representing them in a YANG data model, key distribution can be automated.
            
          
          
          
        
        
          
            Network Configuration Access Control Model
            
            
            
            
              The standardization of network configuration interfaces for use with the Network Configuration Protocol (NETCONF) or the RESTCONF protocol requires a structured and secure operating environment that promotes human usability and multi-vendor interoperability. There is a need for standard mechanisms to restrict NETCONF or RESTCONF protocol access for particular users to a preconfigured subset of all available NETCONF or RESTCONF protocol operations and content. This document defines such an access control model.
              This document obsoletes RFC 6536.
            
          
          
          
          
        
        
          
            A Common YANG Data Model for Layer 2 and Layer 3 VPNs
            
            
            
            
            
            
              This document defines a common YANG module that is meant to be reused by various VPN-related modules such as Layer 3 VPN and Layer 2 VPN network models.
            
          
          
          
        
        
          
            A Common YANG Data Model for Attachment Circuits
            
              Orange
            
            
              Juniper
            
            
              Telefonica
            
            
              Nokia
            
            
              Huawei Technologies
            
            
            
                 The document specifies a common Attachment Circuits (ACs) YANG
   module, which is designed with the intent to be reusable by other
   models.  For example, this common model can be reused by service
   models to expose ACs as a service, service models that require
   binding a service to a set of ACs, network and device models to
   provision ACs, etc.

              
            
          
          
        
        
          
            Virtual Router Redundancy Protocol (VRRP) Version 3 for IPv4 and IPv6
            
            
            
            
              This document defines version 3 of the Virtual Router Redundancy Protocol (VRRP) for IPv4 and IPv6. It obsoletes RFC 5798, which previously specified VRRP (version 3). RFC 5798 obsoleted RFC 3768, which specified VRRP (version 2) for IPv4. VRRP specifies an election protocol that dynamically assigns responsibility for a Virtual Router to one of the VRRP Routers on a LAN. The VRRP Router controlling the IPv4 or IPv6 address(es) associated with a Virtual Router is called the Active Router, and it forwards packets routed to these IPv4 or IPv6 addresses. Active Routers are configured with virtual IPv4 or IPv6 addresses, and Backup Routers infer the address family of the virtual addresses being advertised based on the IP protocol version. Within a VRRP Router, the Virtual Routers in each of the IPv4 and IPv6 address families are independent of one another and always treated as separate Virtual Router instances. The election process provides dynamic failover in the forwarding responsibility should the Active Router become unavailable. For IPv4, the advantage gained from using VRRP is a higher-availability default path without requiring configuration of dynamic routing or router discovery protocols on every end-host. For IPv6, the advantage gained from using VRRP for IPv6 is a quicker switchover to Backup Routers than can be obtained with standard IPv6 Neighbor Discovery mechanisms.
            
          
          
          
        
        
          
            Network Configuration Protocol (NETCONF)
            
            
            
            
            
            
              The Network Configuration Protocol (NETCONF) defined in this document provides mechanisms to install, manipulate, and delete the configuration of network devices. It uses an Extensible Markup Language (XML)-based data encoding for the configuration data as well as the protocol messages. The NETCONF protocol operations are realized as remote procedure calls (RPCs). This document obsoletes RFC 4741. [STANDARDS-TRACK]
            
          
          
          
        
        
          
            A YANG Network Data Model for Layer 3 VPNs
            
            
            
            
            
            
            
              As a complement to the Layer 3 Virtual Private Network Service Model (L3SM), which is used for communication between customers and service providers, this document defines an L3VPN Network Model (L3NM) that can be used for the provisioning of Layer 3 Virtual Private Network (L3VPN) services within a service provider network. The model provides a network-centric view of L3VPN services.
              The L3NM is meant to be used by a network controller to derive the configuration information that will be sent to relevant network devices. The model can also facilitate communication between a service orchestrator and a network controller/orchestrator.
            
          
          
          
        
        
          
            A YANG Network Data Model for Layer 2 VPNs
            
            
            
            
            
            
              This document defines an L2VPN Network Model (L2NM) that can be used to manage the provisioning of Layer 2 Virtual Private Network (L2VPN) services within a network (e.g., a service provider network). The L2NM complements the L2VPN Service Model (L2SM) by providing a network-centric view of the service that is internal to a service provider. The L2NM is particularly meant to be used by a network controller to derive the configuration information that will be sent to relevant network devices.
              Also, this document defines a YANG module to manage Ethernet segments and the initial versions of two IANA-maintained modules that include a set of identities of BGP Layer 2 encapsulation types and pseudowire types.
            
          
          
          
        
        
          
            Bidirectional Forwarding Detection (BFD)
            
            
            
            
              This document describes a protocol intended to detect faults in the bidirectional path between two forwarding engines, including interfaces, data link(s), and to the extent possible the forwarding engines themselves, with potentially very low latency. It operates independently of media, data protocols, and routing protocols. [STANDARDS-TRACK]
            
          
          
          
        
        
          
            OSPF as the Provider/Customer Edge Protocol for BGP/MPLS IP Virtual Private Networks (VPNs)
            
            
            
            
            
              Many Service Providers offer Virtual Private Network (VPN) services to their customers, using a technique in which customer edge routers (CE routers) are routing peers of provider edge routers (PE routers). The Border Gateway Protocol (BGP) is used to distribute the customer's routes across the provider's IP backbone network, and Multiprotocol Label Switching (MPLS) is used to tunnel customer packets across the provider's backbone. This is known as a "BGP/MPLS IP VPN". The base specification for BGP/MPLS IP VPNs presumes that the routing protocol on the interface between a PE router and a CE router is BGP. This document extends that specification by allowing the routing protocol on the PE/CE interface to be the Open Shortest Path First (OSPF) protocol.
              This document updates RFC 4364. [STANDARDS-TRACK]
            
          
          
          
        
        
          
            OSPFv3 as a Provider Edge to Customer Edge (PE-CE) Routing Protocol
            
            
            
            
            
            
            
              Many Service Providers (SPs) offer Virtual Private Network (VPN) services to their customers using a technique in which Customer Edge (CE) routers are routing peers of Provider Edge (PE) routers. The Border Gateway Protocol (BGP) is used to distribute the customer's routes across the provider's IP backbone network, and Multiprotocol Label Switching (MPLS) is used to tunnel customer packets across the provider's backbone. Support currently exists for both IPv4 and IPv6 VPNs; however, only Open Shortest Path First version 2 (OSPFv2) as PE-CE protocol is specified. This document extends those specifications to support OSPF version 3 (OSPFv3) as a PE-CE routing protocol. The OSPFv3 PE-CE functionality is identical to that of OSPFv2 except for the differences described in this document. [STANDARDS-TRACK]
            
          
          
          
        
        
          
            Authentication/Confidentiality for OSPFv3
            
            
            
            
              This document describes means and mechanisms to provide authentication/confidentiality to OSPFv3 using an IPv6 Authentication Header/Encapsulating Security Payload (AH/ESP) extension header. [STANDARDS-TRACK]
            
          
          
          
        
        
          
            OSPFv2 HMAC-SHA Cryptographic Authentication
            
            
            
            
            
            
            
            
            
              This document describes how the National Institute of Standards and Technology (NIST) Secure Hash Standard family of algorithms can be used with OSPF version 2's built-in, cryptographic authentication mechanism. This updates, but does not supercede, the cryptographic authentication mechanism specified in RFC 2328. [STANDARDS-TRACK]
            
          
          
          
        
        
          
            Security Extension for OSPFv2 When Using Manual Key Management
            
            
            
            
            
            
              The current OSPFv2 cryptographic authentication mechanism as defined in RFCs 2328 and 5709 is vulnerable to both inter-session and intra- session replay attacks when using manual keying. Additionally, the existing cryptographic authentication mechanism does not cover the IP header. This omission can be exploited to carry out various types of attacks.
              This document defines changes to the authentication sequence number mechanism that will protect OSPFv2 from both inter-session and intra- session replay attacks when using manual keys for securing OSPFv2 protocol packets. Additionally, we also describe some changes in the cryptographic hash computation that will eliminate attacks resulting from OSPFv2 not protecting the IP header.
            
          
          
          
        
        
          
            Supporting Authentication Trailer for OSPFv3
            
            
            
            
            
              Currently, OSPF for IPv6 (OSPFv3) uses IPsec as the only mechanism for authenticating protocol packets. This behavior is different from authentication mechanisms present in other routing protocols (OSPFv2, Intermediate System to Intermediate System (IS-IS), RIP, and Routing Information Protocol Next Generation (RIPng)). In some environments, it has been found that IPsec is difficult to configure and maintain and thus cannot be used. This document defines an alternative mechanism to authenticate OSPFv3 protocol packets so that OSPFv3 does not depend only upon IPsec for authentication.
              The OSPFv3 Authentication Trailer was originally defined in RFC 6506. This document obsoletes RFC 6506 by providing a revised definition, including clarifications and refinements of the procedures.
            
          
          
          
        
        
          
            RESTCONF Protocol
            
            
            
            
            
              This document describes an HTTP-based protocol that provides a programmatic interface for accessing data defined in YANG, using the datastore concepts defined in the Network Configuration Protocol (NETCONF).
            
          
          
          
        
        
          
            Using the NETCONF Protocol over Secure Shell (SSH)
            
            
            
              This document describes a method for invoking and running the Network Configuration Protocol (NETCONF) within a Secure Shell (SSH) session as an SSH subsystem. This document obsoletes RFC 4742. [STANDARDS-TRACK]
            
          
          
          
        
        
          
            The Transport Layer Security (TLS) Protocol Version 1.3
            
            
            
              This document specifies version 1.3 of the Transport Layer Security (TLS) protocol. TLS allows client/server applications to communicate over the Internet in a way that is designed to prevent eavesdropping, tampering, and message forgery.
              This document updates RFCs 5705 and 6066, and obsoletes RFCs 5077, 5246, and 6961. This document also specifies new requirements for TLS 1.2 implementations.
            
          
          
          
        
        
          
            The IETF XML Registry
            
            
            
              This document describes an IANA maintained registry for IETF standards which use Extensible Markup Language (XML) related items such as Namespaces, Document Type Declarations (DTDs), Schemas, and Resource Description Framework (RDF) Schemas.
            
          
          
          
          
        
        
          
            YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)
            
            
            
              YANG is a data modeling language used to model configuration and state data manipulated by the Network Configuration Protocol (NETCONF), NETCONF remote procedure calls, and NETCONF notifications. [STANDARDS-TRACK]
            
          
          
          
        
      
      
        Informative References
        
          
            Full ACaaS Tree Structure
            
              
            
            
          
        
        
          
            Example of AC SVC Instance Data
            
              
            
            
          
        
        
          
            pyang
            
              
            
            
          
        
        
          
            IEEE Standard for Local and metropolitan area networks - Station and Media Access Control Connectivity Discovery
            
              IEEE
            
            
          
        
        
          
            IEEE Standard for Local and Metropolitan Area Networks--Link Aggregation
            
              IEEE
            
            
          
        
        
          
            Synchronization layer functions for frequency synchronization based on the physical layer
            
              ITU-T
            
            
          
        
        
          
            Service Function Chaining (SFC) Architecture
            
            
            
            
              This document describes an architecture for the specification, creation, and ongoing maintenance of Service Function Chains (SFCs) in a network. It includes architectural concepts, principles, and components used in the construction of composite services through deployment of SFCs, with a focus on those to be standardized in the IETF. This document does not propose solutions, protocols, or extensions to existing protocols.
            
          
          
          
        
        
          
            A Framework for Network Slices in Networks Built from IETF Technologies
            
            
            
            
            
            
            
            
            
              This document describes network slicing in the context of networks built from IETF technologies. It defines the term "IETF Network Slice" to describe this type of network slice and establishes the general principles of network slicing in the IETF context.
              The document discusses the general framework for requesting and operating IETF Network Slices, the characteristics of an IETF Network Slice, the necessary system components and interfaces, and the mapping of abstract requests to more specific technologies. The document also discusses related considerations with monitoring and security.
              This document also provides definitions of related terms to enable consistent usage in other IETF documents that describe or use aspects of IETF Network Slices.
            
          
          
          
        
        
          
            A Network YANG Data Model for Attachment Circuits
            
              Orange
            
            
              Juniper
            
            
              Telefonica
            
            
              Nokia
            
            
              Huawei Technologies
            
            
            
                 This document specifies a network model for attachment circuits.  The
   model can be used for the provisioning of attachment circuits prior
   or during service provisioning (e.g., VPN, Network Slice Service).  A
   companion service model is specified in the YANG Data Models for
   Bearers and 'Attachment Circuits'-as-a-Service (ACaaS) (I-D.ietf-
   opsawg-teas-attachment-circuit).

   The module augments the base network ('ietf-network') and the Service
   Attachment Point (SAP) models with the detailed information for the
   provisioning of attachment circuits in Provider Edges (PEs).

              
            
          
          
        
        
          
            A YANG Data Model for Augmenting VPN Service and Network Models with Attachment Circuits
            
              Orange
            
            
              Juniper
            
            
              Nokia
            
            
              Telefonica
            
            
            
                 The document specifies a module that updates existing service (i.e.,
   the Layer 2 Service Model (L2SM) and the Layer 3 Service Model
   (L3SM)) and network (i.e., the Layer 2 Network Model (L2NM) and the
   Layer 3 Network Model (L3NM)) Virtual Private Network (VPN) modules
   with the required information to bind specific VPN services to
   Attachment Circuits (ACs) that are created using the AC service
   ("ietf-ac-svc") and network ("ietf-ac-ntw") models.

              
            
          
          
        
        
          
            A YANG Data Model for Layer 2 Virtual Private Network (L2VPN) Service Delivery
            
            
            
            
            
            
              This document defines a YANG data model that can be used to configure a Layer 2 provider-provisioned VPN service. It is up to a management system to take this as an input and generate specific configuration models to configure the different network elements to deliver the service. How this configuration of network elements is done is out of scope for this document.
              The YANG data model defined in this document includes support for point-to-point Virtual Private Wire Services (VPWSs) and multipoint Virtual Private LAN Services (VPLSs) that use Pseudowires signaled using the Label Distribution Protocol (LDP) and the Border Gateway Protocol (BGP) as described in RFCs 4761 and 6624.
              The YANG data model defined in this document conforms to the Network Management Datastore Architecture defined in RFC 8342.
            
          
          
          
        
        
          
            YANG Data Model for L3VPN Service Delivery
            
            
            
            
            
            
              This document defines a YANG data model that can be used for communication between customers and network operators and to deliver a Layer 3 provider-provisioned VPN service. This document is limited to BGP PE-based VPNs as described in RFCs 4026, 4110, and 4364. This model is intended to be instantiated at the management system to deliver the overall service. It is not a configuration model to be used directly on network elements. This model provides an abstracted view of the Layer 3 IP VPN service configuration components. It will be up to the management system to take this model as input and use specific configuration models to configure the different network elements to deliver the service. How the configuration of network elements is done is out of scope for this document.
              This document obsoletes RFC 8049; it replaces the unimplementable module in that RFC with a new module with the same name that is not backward compatible. The changes are a series of small fixes to the YANG module and some clarifications to the text.
            
          
          
          
        
        
          
            Dynamic Service Negotiation: The Connectivity Provisioning Negotiation Protocol (CPNP)
            
            
            
            
            
            
              This document defines the Connectivity Provisioning Negotiation Protocol (CPNP), which is designed to facilitate the dynamic negotiation of service parameters.
              CPNP is a generic protocol that can be used for various negotiation purposes that include (but are not necessarily limited to) connectivity provisioning services, storage facilities, Content Delivery Networks, etc.
            
          
          
          
        
        
          
            Peering API
            
              Amazon
            
            
              FullCtl
            
            
              Meta
            
            
              Google
            
            
              Cloudflare
            
            
            
                 We propose an API standard for BGP Peering, also known as interdomain
   interconnection through global Internet Routing.  This API offers a
   standard way to request public (settlement-free) peering, verify the
   status of a request or BGP session, and list potential connection
   locations.  The API is backed by PeeringDB OIDC, the industry
   standard for peering authentication.  We also propose future work to
   cover private peering, and alternative authentication methods.

              
            
          
          
        
        
          
            A Framework for Automating Service and Network Management with YANG
            
            
            
            
            
            
            
              Data models provide a programmatic approach to represent services and networks. Concretely, they can be used to derive configuration information for network and service components, and state information that will be monitored and tracked. Data models can be used during the service and network management life cycle (e.g., service instantiation, service provisioning, service optimization, service monitoring, service diagnosing, and service assurance). Data models are also instrumental in the automation of network management, and they can provide closed-loop control for adaptive and deterministic service creation, delivery, and maintenance.
              This document describes a framework for service and network management automation that takes advantage of YANG modeling technologies. This framework is drawn from a network operator perspective irrespective of the origin of a data model; thus, it can accommodate YANG modules that are developed outside the IETF.
            
          
          
          
        
        
          
            A YANG Data Model for Routing Management (NMDA Version)
            
            
            
            
            
              This document specifies three YANG modules and one submodule. Together, they form the core routing data model that serves as a framework for configuring and managing a routing subsystem. It is expected that these modules will be augmented by additional YANG modules defining data models for control-plane protocols, route filters, and other functions. The core routing data model provides common building blocks for such extensions -- routes, Routing Information Bases (RIBs), and control-plane protocols.
              The YANG modules in this document conform to the Network Management Datastore Architecture (NMDA). This document obsoletes RFC 8022.
            
          
          
          
        
        
          
            YANG Model for Border Gateway Protocol (BGP-4)
            
              Kloud Services
            
            
              Arrcus
            
            
              Huawei
            
            
              Juniper Networks
            
            
            
                 This document defines a YANG data model for configuring and managing
   BGP, including protocol, policy, and operational aspects, such as
   RIB, based on data center, carrier, and content provider operational
   requirements.

              
            
          
          
        
        
          
            YANG Tree Diagrams
            
            
            
            
              This document captures the current syntax used in YANG module tree diagrams. The purpose of this document is to provide a single location for this definition. This syntax may be updated from time to time based on the evolution of the YANG language.
            
          
          
          
          
        
        
          
            Provider Provisioned Virtual Private Network (VPN) Terminology
            
            
            
            
              The widespread interest in provider-provisioned Virtual Private Network (VPN) solutions lead to memos proposing different and overlapping solutions. The IETF working groups (first Provider Provisioned VPNs and later Layer 2 VPNs and Layer 3 VPNs) have discussed these proposals and documented specifications. This has lead to the development of a partially new set of concepts used to describe the set of VPN services.
              To a certain extent, more than one term covers the same concept, and sometimes the same term covers more than one concept. This document seeks to make the terminology in the area clearer and more intuitive. This memo provides information for the Internet community.
            
          
          
          
        
        
          
            Codification of AS 0 Processing
            
            
            
            
            
            
              This document updates RFC 4271 and proscribes the use of Autonomous System (AS) 0 in the Border Gateway Protocol (BGP) OPEN, AS_PATH, AS4_PATH, AGGREGATOR, and AS4_AGGREGATOR attributes in the BGP UPDATE message.
            
          
          
          
        
        
          
            Guidelines for Authors and Reviewers of Documents Containing YANG Data Models
            
              YumaWorks
            
            
              Orange
            
            
              Huawei
            
            
            
                 This memo provides guidelines for authors and reviewers of
   specifications containing YANG modules, including IANA-maintained
   modules.  Recommendations and procedures are defined, which are
   intended to increase interoperability and usability of Network
   Configuration Protocol (NETCONF) and RESTCONF protocol
   implementations that utilize YANG modules.  This document obsoletes
   RFC 8407.

   Also, this document updates RFC 8126 by providing additional
   guidelines for writing the IANA considerations for RFCs that specify
   IANA-maintained modules.  The document also updates RFC 6020 by
   clarifying how modules and their revisions are handled by IANA.

              
            
          
          
        
        
          
            Policy Quality of Service (QoS) Information Model
            
            
            
            
            
            
            
              This document presents an object-oriented information model for representing Quality of Service (QoS) network management policies. This document is based on the IETF Policy Core Information Model and its extensions. It defines an information model for QoS enforcement for differentiated and integrated services using policy. It is important to note that this document defines an information model, which by definition is independent of any particular data storage mechanism and access protocol.
            
          
          
          
        
        
          
            Route Leak Prevention and Detection Using Roles in UPDATE and OPEN Messages
            
            
            
            
            
            
            
              Route leaks are the propagation of BGP prefixes that violate assumptions of BGP topology relationships, e.g., announcing a route learned from one transit provider to another transit provider or a lateral (i.e., non-transit) peer or announcing a route learned from one lateral peer to another lateral peer or a transit provider. These are usually the result of misconfigured or absent BGP route filtering or lack of coordination between autonomous systems (ASes). Existing approaches to leak prevention rely on marking routes by operator configuration, with no check that the configuration corresponds to that of the External BGP (eBGP) neighbor, or enforcement of the two eBGP speakers agreeing on the peering relationship. This document enhances the BGP OPEN message to establish an agreement of the peering relationship on each eBGP session between autonomous systems in order to enforce appropriate configuration on both sides. Propagated routes are then marked according to the agreed relationship, allowing both prevention and detection of route leaks.
            
          
          
          
        
        
          
            The TCP Authentication Option
            
            
            
            
            
              This document specifies the TCP Authentication Option (TCP-AO), which obsoletes the TCP MD5 Signature option of RFC 2385 (TCP MD5). TCP-AO specifies the use of stronger Message Authentication Codes (MACs), protects against replays even for long-lived TCP connections, and provides more details on the association of security with TCP connections than TCP MD5. TCP-AO is compatible with either a static Master Key Tuple (MKT) configuration or an external, out-of-band MKT management mechanism; in either case, TCP-AO also protects connections when using the same MKT across repeated instances of a connection, using traffic keys derived from the MKT, and coordinates MKT changes between endpoints. The result is intended to support current infrastructure uses of TCP MD5, such as to protect long-lived connections (as used, e.g., in BGP and LDP), and to support a larger set of MACs with minimal other system and operational changes. TCP-AO uses a different option identifier than TCP MD5, even though TCP-AO and TCP MD5 are never permitted to be used simultaneously. TCP-AO supports IPv6, and is fully compatible with the proposed requirements for the replacement of TCP MD5. [STANDARDS-TRACK]
            
          
          
          
        
        
          
            RIP Version 2
            
            
            
              This document specifies an extension of the Routing Information Protocol (RIP) to expand the amount of useful information carried in RIP messages and to add a measure of security. [STANDARDS-TRACK]
            
          
          
          
          
        
        
          
            RIPng for IPv6
            
            
            
            
              This document specifies a routing protocol for an IPv6 internet. It is based on protocols and algorithms currently in wide use in the IPv4 Internet [STANDARDS-TRACK]
            
          
          
          
        
        
          
            A YANG Data Model for the Routing Information Protocol (RIP)
            
            
            
            
            
              This document describes a data model for the management of the Routing Information Protocol (RIP). Both RIP version 2 and RIPng are covered. The data model includes definitions for configuration, operational state, and Remote Procedure Calls (RPCs).
              The YANG data model in this document conforms to the Network Management Datastore Architecture (NMDA).
            
          
          
          
        
        
          
            A YANG Data Model for the RFC 9543 Network Slice Service
            
              Huawei Technologies
            
            
              Huawei Technologies
            
            
              Ciena
            
            
              Cisco Systems, Inc
            
            
              Cisco Systems, Inc
            
            
            
                 This document defines a YANG data model for RFC 9543 Network Slice
   Service.  The model can be used in the Network Slice Service
   interface between a customer and a provider that offers RFC 9543
   Network Slice Services.

              
            
          
          
        
        
          
            Updated Security Considerations for the MD5 Message-Digest and the HMAC-MD5 Algorithms
            
            
            
            
              This document updates the security considerations for the MD5 message digest algorithm. It also updates the security considerations for HMAC-MD5. This document is not an Internet Standards Track specification; it is published for informational purposes.
            
          
          
          
        
        
          
            Analysis of BGP, LDP, PCEP, and MSDP Issues According to the Keying and Authentication for Routing Protocols (KARP) Design Guide
            
            
            
            
            
              This document analyzes TCP-based routing protocols, the Border Gateway Protocol (BGP), the Label Distribution Protocol (LDP), the Path Computation Element Communication Protocol (PCEP), and the Multicast Source Distribution Protocol (MSDP), according to guidelines set forth in Section 4.2 of "Keying and Authentication for Routing Protocols Design Guidelines", RFC 6518.
            
          
          
          
        
      
    
    


      Examples
      This section includes a non-exhaustive list of examples to illustrate the use of the service models defined in this document. An example instance data can also be found at .
      
        Create a New Bearer
        An example of a request message body to create a bearer is shown in .
        
          Example of a Message Body to Create a New Bearer
          
        
        A "bearer-reference" is then generated by the controller for this bearer.  shows the example of a response message body that is sent by the controller to reply to a GET request:
        
          Example of a Response Message Body with the Bearer Reference
          
        
        Note that the response also indicates that Sync Phy mechanism is supported for this bearer.
      
      
        Create an AC over an Existing Bearer
        An example of a request message body to create a simple AC over an existing bearer is shown in . The bearer reference is assumed to be known to both the customer and the network provider. Such a reference can be retrieved, e.g., following the example described in  or using other means (including, exchanged out-of-band or via proprietary APIs).
        
          Example of a Message Body to Request an AC over an Existing Bearer
          
        
         shows the message body of a response received from the controller and which indicates the "cvlan-id" that was assigned for the requested AC.
        
          Example of a Message Body of a Response to Assign a CVLAN ID
          
        
      
      
        Create an AC for a Known Peer SAP
        An example of a request to create a simple AC, when the peer SAP is known, is shown in . In this example, the peer SAP identifier points to an identifier of an SF. The (topological) location of that SF is assumed to be known to the network controller. For example, this can be determined as part of an on-demand procedure to instantiate an SF in a cloud. That instantiated SF can be granted a connectivity service via the provider network.
        
          Example of a Message Body to Request an AC with a Peer SAP
          
        
         shows the received response with the required informaiton to connect the SF.
        
          Example of a Message Body of a Response to Create an AC with a Peer SAP
          
        
      
      
        One CE, Two ACs
        Let us consider the example of an eNodeB (CE) that is directly connected to the access routers of the mobile backhaul (see ). In this example, two ACs are needed to service the eNodeB (e.g., distinct VLANs for Control and User Planes).
        
          Example of a CE-PE ACs
          
            
            
            
          
        
        An example of a request to create the ACs to service the eNodeB is shown in . This example assumes that static addressing is used for both ACs.
        
          Example of a Message Body to Request Two ACs on the Same Link (Not Recommended)
          
        
         shows the message body of a response received from the controller.
        
          Example of a Message Body of a Response to Create Two ACs on the Same Link (Not Recommended)
          
        
        The example shown  is not optimal as it includes many redundant data.  shows a more compact request that factorizes all the redundant data.
        
          Example of a Message Body to Request Two ACs on the Same Link (Node Profile)
          
        
        A customer may request adding a new AC by simply referring to an existing per-node AC profile as shown in . This AC inherits all the data that was enclosed in the indicated per-node AC profile (IP addressing, routing, etc.).
        
          Example of a Message Body to Add a new AC over an existing link (Node Profile)
          
        
      
      
        Control Precedence over Multiple ACs
        When multiple ACs are requested by the same customer for the same site, the request can tag one of these ACs as "primary" and the other ones as "secondary". An example of such a request is shown in . In this example, both ACs are bound to the same "group-id", and the "precedence" data node is set as a function of the intended role of each AC (primary or secondary).
        
          An Example Topology for AC Precedence Enforcement
          
            
            
            
          
        
        
          Example of a Message Body to Associate a Precedence Level with ACs
          
        
      
      
        Create Multiple ACs Bound to Multiple CEs
         shows an example of CEs that are interconnected by a service provider network.
        
          Network Topology Example
          
            
            
            
          
        
         depicts an example of the message body of a response to a request to instantiate the various ACs that are shown in .
        
          Example of a Message Body of a Request to Create Multiple ACs bound to Multiple CEs
          
        
      
      
        Binding Attachment Circuits to an IETF Network Slice
        This example shows how the AC service model complements the model defined in "A YANG Data Model for the RFC 9543 Network Slice Service"  to connect a site to a Slice Service.
        First,  describes the end-to-end network topology as well the orchestration scopes:
        
          
            The topology is made up of two sites ("site1" and "site2"), interconnected via a Transport Network (e.g., IP/MPLS network). An SF is deployed within each site in a dedicated IP subnet.
          
          
            A 5G Service Management and Orchestration (SMO) is responsible for the deployment of SFs and the indirect management of a local Gateway (i.e., CE).
          
          
            An IETF Network Slice Controller (NSC)  is responsible for the deployment of IETF Network Slices across the Transport Network.
          
        
        SFs are deployed within each site.
        
          An Example of a Network Topology Used to Deploy Slices
          
            
            
                    <---------+-------->        <----+---->
       Site1             Transport Network              Site2
   .---.                  .--------------.                 .---.
   |SF1|                  |              |                 |SF2|
   '-+-'   .---.        .---.          .---.        .---.  '-+-'
     |     |   |        |   |          |   |        |   |    |
   --+-----+GW1+--------+PE1|          |PE2+--------+GW2+----+--
       ^   |   |    ^   |   |          |   |   ^    |   |  ^
       |   '---'    |   '-+-'          '-+-'   |    '---'  |
       |            |     |              |     |           |
       |            |     '--------------'     |           |
     LAN1           |                          |          LAN2
198.51.100.0/24     |                          |  203.0.113.0/24
                    |                          |
                    |                          |
            Physical Link ID:           Physical Link ID:
              bearerX@site1               bearerX@site2

]]>
          
        
         describes the logical connectivity enforced thanks to both IETF Network Slice and ACaaS models.
        
          Logical Overview
          
            
            
             AS 65550
 .---.                     .--------.                    .---.
 |SF1|       192.0.2.0/30  |        |   192.0.2.4/30     |SF2|
 '-+-'   .---.          .--+.      .+--.          .---.  '-+-'
   |     |   |.1      .2|   |      |   |.6      .5|   |    |
 --+-----+GW1+----------+PE1|      |PE2+----------+GW2+----+----
         |   | vlan-id  |   |      |   | vlan-id  |   |
         '---'   100    '--+'      '+--'   200    '---'
198.51.100.0/24            |        |             203.0.113.0/24
                           '--------+'
                         sdp1      sdp2
             <----------> <------------> <------->
             Attachment   Network Slice   Attachment
             Circuit "ac1"    EMBB_UP     Circuit "ac2"                

 * "ac1" properties:
 - bearer-reference: bearerX@site1
 - vlan-id: 100
 - CE address (GW1): 192.0.2.1/30
 - PE address: 192.0.2.2/30
 - Routing: static 198.51.100.0/24 via
            192.0.2.1 tag primary_UP_slice

 * "ac2" properties:
 - bearer-reference: bearerY@site2
 - vlan-id: 200
 - CE address (GW2): 192.0.2.5/30
 - PE address: 192.0.2.6/30
 - Routing: BGP local-as: 65536 (Provider ASN)
                peer-as: 65550 (customer ASN)
                remote-address: 192.0.2.5 (Customer address)
]]>
          
        
         shows the message body of the request to create the required ACs using the ACaaS module.
        
          Message Body of a Request to Create Required ACs
          
        
         shows the message body of a response received from the controller.
        
          Example of a Message Body of a Response Indicating the Creation of the ACs
          
        
         shows the message body of the request to create a Slice Service bound to the ACs created using . Only references to these ACs are included in the Slice Service request.
        
          Message Body of a Request to Create a Slice Service Referring to the ACs
          
        
      
      
        Connecting a Virtualized Environment Running in a Cloud Provider
        This example () shows how the AC service model can be used to connect a Cloud Infrastructure to a service provider network. This example makes the following assumptions:
        
            A customer (e.g., Mobile Network Team or partner) has a virtualized infrastructure running in a Cloud Provider. A simplistic deployment is represented here with a set of Virtual Machines running in a Virtual Private Environment. The deployment and management of this infrastructure is achieved via private APIs that are supported by the Cloud Provider: this realization is out of the scope of this document.
          
          
            The connectivity to the Data Center is achieved thanks to a service based on direct attachment (physical connection), which is delivered upon ordering via an API exposed by the Cloud Provider. When ordering that connection, a unique "Connection Identifier" is generated and returned via the API.
          
          
            The customer provisions the networking logic within the Cloud Provider based on that unique connection identifier (i.e., logical interfaces, IP addressing, and routing).
          
        
        
          An Example of Realization for Connecting a Cloud Site
          
            
            
            
          
        
         illustrates the pre-provisioning logic for the physical connection to the Cloud Provider. After this connection is delivered to the service provider, the network inventory is updated with "bearer-reference" set to the value of the "Connection Identifier".
        
          Illustration of Pre-provisioning
          
            
            
            

               Connection Created with "Connection ID:1234-56789"
               <------------------------------------------------
                                        x
                                        x
                                        x
                                        x

       Physical Connection 1234-56789 is delivered and
                         connected to PE1

       Network Inventory Updated with:
         bearer-reference: 1234-56789 for PE1/Interface "If-A"
]]>
          
        
        Next, API workflows can be initiated by:
        
          
            The Cloud Provider for the configuration per Step (3) above.
          
          
            The Service provider network via the ACaaS model. This request can be used in conjunction with additional requests based on the L3SM (VPN provisioning) or Network Slice Service model (5G hybrid Cloud deployment).
          
        
         shows the message body of the request to create the required ACs to connect the Cloud Provider Virtualized (VM) using the Attachment Circuit module.
        
          Message Body of a Request to Create the ACs for Connecting to the Cloud Provider
          
        
         shows the message body of the response received from the provider. Note that this Cloud Provider mandates the use of MD5 authentication for establishing BGP connections.
        
          
            The module supports MD5 to basically accommodate the installed BGP base (including by some Cloud Providers). Note that MD5 suffers from the security weaknesses discussed in  and .
          
        
        
          Message Body of a Response to the Request to Create ACs for Connecting to the Cloud Provider
          
        
      
      
        Connect Customer Network Through BGP
        CE-PE routing using BGP is a common scenario in the context of MPLS VPNs and is widely used in enterprise networks. In the example depicted in , the CE routers are customer-owned devices belonging to an AS (ASN 65536). CEs are located at the edge of the provider's network (PE, or Provider Edge) and use point-to-point interfaces to establish BGP sessions. The point-to-point interfaces rely upon a physical bearer ("line-113") to reach the provider network.
        
          Illustration of Provider Network Scenario
          
            
            
            
          
        
        The attachment circuit in this case use a SAP identifier to refer to the physical interface used for the connection between the PE and the CE. The attachment circuit includes all the additional logical attributes to describe the connection between the two ends, including VLAN information and IP addressing. Also, the configuration details of the BGP session makes use of peer group details instead of defining the entire configuration inside the 'neighbor' data node.
        
          Message Body of a Request to Create ACs for Connecting CEs to a Provider Network
          
        
        This scenario allows the provider to maintain a list of ACs belonging to the same customer without requiring the full service configuration.
      
      
        Interconnection via Internet eXchange Points (IXPs)
        This section illustrates how to use the AC service model for interconnection purposes. To that aim, the document assumes a simplified Internet eXchange Point (IXP) configuration without zooming into IXP deployment specifics. Let us assume that networks are interconnected via a Layer 2 facility. BGP is used to exchange routing information and reachability announcements between those networks. The same approach can be used to negotiate interconnection between two networks and without involving an IXP.
        The following subsections exemplify a deployment flow, but BGP sessions can be managed without having to execute systematically all the steps detailed hereafter.
        
          Retrieve Interconnection Locations
           shows an example a message body of a request to retrieve a list of interconnection locations. The request includes a customer name and an ASN to filter out the locations.
          
            Message Body of a Request to Retrieve Interconnection Locations
            
          
           provides an example of a response received from the server with a list of available interconnection locations.
          
            Message Body of a Response to Retrieve Interconnection Locations
            
          
        
        
          Create Bearers and Retrieve Bearer References
          A peer can then use the location information and select the ones where it can request new bearers. As shown in , the request includes a location reference which is known to the server (returned in ).
          
            Message Body of a Request to Create a Bearer using a Provider-Assigned Reference
            
          
          The bearer is then activated by the server as shown in . A "bearer-reference" is also returned. That reference can be used for subsequent AC activation requests.
          
            Message Body of a Response to Create a Bearer in a Specific Location
            
          
        
        
          Manage ACs and BGP Sessions
          As depicted in , each network connects to the IXP switch via a bearer over which an AC is created.
          
            Simple Interconnection Topology
            
              
              
              
            
          
          The AC configuration () includes parameters such as VLAN configuration, IP addresses, MTU, and any additional settings required for connectivity. The peering location is inferred from the "bearer-reference".
          
            Message Body of a Request to Create an AC to Connect to an IXP
            
          
           shows the received response with the required information for the activation of the AC.
          
            Message Body of a Response to an AC Request to Connect to an IXP
            
          
          Once the ACs are established, BGP peering sessions can be configured between routers of the participating networks. BGP sessions can be established via a route server or between two networks. For the sake of illustration, let us assume that BGP sessions are established directly between two network.  shows an example of a request to add a BGP session to an existing AC. The properties of that AC are not repeated in this request because that information is already communicated during the creation of the AC.
          
            Message Body of a Request to Create a BGP Session over an AC
            
          
           provides the example of a response which indicates that the request is awaiting validation. The response includes also a server-assigned reference for this BGP session.
          
            Message Body of a Response for a BGP Session Awaiting Validation
            
          
          Once validation is accomplished, a status update is communicated back to the requestor. The BGP session can then be established over the AC. The BGP session configuration includes parameters such as neighbor IP addresses, ASNs, authentication settings (if required), etc. The configuration is triggered at each side of the BGP connection.
          
            Message Body of a Response to Report All Active BGP sessions over an AC
            
          
        
      
      
        Connectivity of Cloud Network Functions
        
          Scope
          This section demonstrates how the AC service model permits managing connectivity requirements for complex Network Functions (NFs) - containerized or virtualized -  that are typically deployed in Telco networks. This integration leverages the concept of "parent AC" to decouple physical and logical connectivity so that several ACs can shares Layer 2 and Layer 3 resources. This approach provides flexibility, scalability, and API stability.
          The NFs have the following characteristics:
          
            
              The NF is distributed on a set of compute nodes with scaled-out and redundant instances.
            
            
              The NF has two distinct type of instances: user plane ("nf-up") and routing control plane ("nf-cp").
            
            
              The user plane component can be distributed among the first 8 compute nodes ("compute-01" to "compute-08") to achieve high performance.
            
            
              The control plane is deployed in a redundant fashion on two instances running on distinct compute nodes ("compute-09" and "compute-10").
            
            
              The NF is attached to distinct networks, each making use of a dedicated VLAN. These VLANs are therefore instantiated as separate ACs. From a realization standpoint, the NF interface connectivity is generally provided thanks to MacVLAN or Single Root I/O Virtualization (SR-IOV). For the sake of simplicity only two VLANs are presented in this example, additional VLANs are configured following a similar logic.
            
          
        
        
          Physical Infrastructure
           describes the physical infrastructure. The compute nodes (customer) are attached to the provider infrastructure thanks to a set of physical links on which attachment circuits are provisioned (i.e., "compute-XX-nicY"). The provider infrastructure can be realized in multiple ways, such as IP Fabric, Layer 2/Layer 3 Edge Routers. This document does not intend to detail these aspects.
          
            Example Physical Topology for Cloud Deployment
            
              
              
              
            
          
        
        
          NFs Deployment
          The NFs are deployed on this infrastructure in the following way:
          
            
              Configuration of a parent AC as a centralized attachment for "vlan 100". The parent AC captures Layer 2 and Layer 3 properties for this VLAN: vlan-id, IP default gateway and subnet, IP address pool for NFs endpoints, static routes with BFD to user plane, and BGP configuration to control plane NFs. In addition, the IP addresses of the user plane ("nf-up") instances are protected using BFD.
            
            
              Configuration of a parent AC as a centralized attachment for "vlan 200". This vlan is for Layer 2 connectivity between NFs (no IP configuration in the provider network).
            
            
              "Child ACs" binding bearers to parent ACs for "vlan 100" and "vlan 200".
            
            
              The deployment of the network service to all compute nodes ("compute-01" to "compute-10"), even though the NF is not instantiated on "compute-07"/"compute-08". This approach permits handling compute failures and scale-out scenarios in a reactive and flexible fashion thanks to a pre-provisioned networking logic.
            
          
          
            Logical Topology of the NFs Deployment
            
              
              
                             |            |          |
 ||nf-up1||--------vlan-100---------------|            v          |
 ||      ||--------vlan-200---------------|  .------------------. |
 |'------'|                               |  | Bridge vlan 100  | |
 compute-01                               |  |     (l2/l3)      | |
 .--------.                               |  |   IP gateway:    | |
 |.------.|.2     <- bfd ->               |  |  192.0.2.254/24  | |
 ||nf-up2||--------vlan-100---------------|  '------------------' |
 ||      ||--------vlan-200---------------|  .------------------. |
 |'------'|                               |  |                  | |
 compute-02                               |  | Bridge vlan 200  | |
                     [...]                |  |    (l2 only)     | |
 .--------.                               |  |                  | |
 |.------.|.6     <- bfd ->               |  '------------------' |
 ||nf-up6||--------vlan-100---------------|                       |
 ||      ||--------vlan-200---------------|                       |
 |'------'|                               |                       |
 compute-06                               |                       |
 .--------.                               |                       |
 |        |---------vlan-100--------------|                       |
 |        |---------vlan-200--------------|                       |
 compute-07                               |                       |
 .--------.                               |                       |
 |        |---------vlan-100--------------|                       |
 |        |---------vlan-200--------------|                       |
 compute-08                               |                       |
 .--------. <----------BGP--------------->|                       |
 |.------.|.9                       .252  |                       |
 ||nf-cp1||--------vlan-100---------------|                       |
 ||      ||--------vlan-200---------------|                       |
 |'------'|                               |                       |
 compute-09                               |                       |
 .--------. <-----------BGP-------------->|                       |
 |.------.|.10                       .253 |                       |
 ||nf-cp2||---------vlan-100--------------|                       |
 ||      ||---------vlan-200--------------|                       |
 |'------'|                               '-----------------------'
 compute-10                                                        
 .-----------------------------------.                             
 |nf-cp routing for VLAN 100         |                             
 |advertises pools with 1:N backup   |                             
 |route.                             |                             
 |BGP UPDATE:                        |                             
 |203.0.113.0/24, NH = 198.51.100.100| ---->                       
 |203.0.113.0/28, NH = 192.0.2.1     |                             
 |203.0.113.16/28, NH = 192.0.2.2    |                             
 |...                                |                             
 |203.0.113.80/28, NH = 192.0.2.6    |                             
 |203.0.113.96/28, NH = 192.0.2.7    |                             
 '-----------------------------------'                              
]]>
            
          
          For readability the payload is displayed as single JSON file (). In practice, several API calls may take place to initialize these resources (e.g., GET requests from the customer to retrieve the IP address pools for NFs on "vlan 100" thanks to parent configuration and BGP configuration, and POST extra routes for user planes and BFD).
          Note that no individual IP address is assigned in the data model for the NF user plane instances (i.e., no "customer-address" in the Child AC). The assignment of IP addresses to the NF endpoints is managed by the Cloud Infrastructure IPAM based on the customer-addresses IP address pool "192.0.2.1-200". Like in any standard LAN-facing scenario, it is assumed that the actual binding of IP endpoints to logical attachments (here Child ACs) relies on a dedicated protocol logic  (typically, ARP or NDP) and is not captured in the data model. Hence, the IP addresses displayed for NF user plane instances are simply examples of a realization approach. Note also that the Control Plane is defined with static IP address assignment on a given AC/bearer to illustrate another deployment alternative.
          
            Message Body for the Configuration of the NF ACs
            
          
        
        
          NF Failure and Scale-Out
          Assuming a failure of "compute-01", the instance "nf-up-1" can be redeployed to "compute-07" by the NF/Cloud Orchestration. The NFs can be scaled-out thanks to the creation of an extra instance "nf-up7" on "compute-08". Since connectivity is pre-provisioned, these operations happen without any API calls. In other words, this redeployment is transparent from the perspective of the configuration of the provider network.
          
            Example of Compute Failure and Scale-out
            
              
              
                           |                       |
 ||nf-up1||---------vlan-100--------------|  nf-up1 moved to      |
 ||      ||---------vlan-200--------------|     compute-07        |
 |'------'|                               |                       |
 compute-07                               |                       |
 .--------.                               |     nf-up7 on         |
 |.------.|.7     < - bfd - >             |    compute-08         |
 ||nf-up7||---------vlan-100--------------|    created for        |
 ||      ||---------vlan-200--------------|     scale-out         |
 |'------'|                               |                       |
 compute-08                               '-----------------------'
]]>
            
          
          Finally, the addition or deletion of compute nodes in the deployment ("compute-11", "compute-12", etc.) involves merely changes on Child ACs and possible routing on the parent AC. In any case, the parent AC is a stable identifier, which can be consumed as a reference by end-to-end service models for VPN configuration such as , Slice Service , etc. This decoupling to a stable identifier provides great benefits in terms of scalability and flexibility since once the reference with the parent AC is implemented, no API call involving the VPN model is needed for any modification in the cloud.
        
      
      
        BFD and Static Addressing
         shows a topology example of a set of CEs connected to a provider network via dedicated bearers. Each of these CE maintains two BFD sessions with the provider network.
        
          Example of Static Addressing with BFD
          
            
            
             .252
+--------+    <---bfd---> .253
]]>
          
        
         shows the message body of the ACaaS configuration to enable the target architecture shown in . This example uses an AC group profile to factorize common data between all involved ACs. It also uses child ACs that inherit the properties of two parent ACs; each terminating in a separate gateway in the provider network.
        
          Message Body for the Configuration of CEs with Static Addressing and BFD Protection
          
        
      
    
    
      Acknowledgments
      This document leverages  and . Thanks to Gyan Mishra for the review.
      Thanks to Ebben Aries for the YANG Doctors review and for providing .
      Thanks to Donald Eastlake for the careful rtg-dir reviews and Tero Kivinen for the sec-dir review.
      Thanks to Luis Miguel Contreras Murillo for the careful Shepherd review.
    
    
      Contributors
      
        Nokia
        
          victor.lopez@nokia.com
        
      
      
        Ribbon Communications
        
          Ivan.Bykov@rbbn.com
        
      
      
        Huawei
        
          bill.wu@huawei.com
        
      
      
        KDDI
        
          ke-oogaki@kddi.com
        
      
      
        Vodafone
        
          luis-angel.munoz@vodafone.com