Networking Working Group Q. Wu
Internet-Draft Huawei
Intended status: Standards Track M. Boucadair
Expires: September 4, 2018 Orange
March 3, 2018

An Architecture for Data Model Driven Network Management: the Network Virtualization Case


Data Model driven network management can be used at various phases of service and network management life cycle such as service instantiation, service provision, optimization, monitoring, and diagnostic. Also, it can be designed to provide closed-loop control for the sake of agile service creation, delivery and maintenance.

This document describes an architecture for data model driven network management with a sample applicability case: network virtualization environments.

Status of This Memo

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This Internet-Draft will expire on September 4, 2018.

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Table of Contents

1. Introduction

As observed in [I-D.arkko-arch-virtualization], many IETF discussions earlier in the summer of 2017 started from a top-down view of new virtualization technologies, but were often unable to explain the necessary delta to the wealth of existing IETF technologies in this space. Therefore, [I-D.arkko-arch-virtualization] considered a bottom-up approach to provide an overview of existing technologies which is aiming at identifying areas for further development.

For years, the IETF was driving the industry transition from an overloaded Software Defined Networking (SDN) buzzword to focus on specific areas such as data modeling-driven management. [RFC7149] provided a first tentative to rationalize that space by identifying concrete technical domains that need to be considered:

Models are key for each of these technical items.

Later, as described in [RFC8199], YANG module developers have taken both top-down and bottom-up approaches to develop modules and establish mapping between network technology and customer requirements on the top or abstracting common construct from various network technologies. At the time of writing this document (2018), we see the large number of data models including configuration models and service models developed or under development in IETF covering much of networking protocols and techniques. In addition, how these models work together to fully configure a device, or manage a set of devices involved in a service aren't developed yet in IETF.

This document takes both bottom up approach and top down approach to provide a framework that discusses the architecture for data model driven network management, with a focus on network virtualization environment.

This document also describes specific YANG modules needed to realize connectivity services and investigate how top down built model (e.g., customer-facing data models) interact with bottom up built model (resource-facing data models) in the context of service delivery and assurance.

2. Architectural Concepts

2.1. Data Models: Layering and Representation

As described in [RFC8199], layering of modules allows for better reusability of lower-layer modules by higher-level modules while limiting duplication of features across layers.

The IETF has developed large number of network level and device level modules, and few service ones. Service level modules follow top down approach and are mostly customer-facing models providing a common model construct for higher level network services, which can be further mapped to network technology-specific models at lower layer.

Network level modules mostly follow bottom up approach and are mostly resource-facing model and describe various aspects of a network infrastructure, including devices and their subsystems, and relevant protocols operating at the link and network layers across multiple devices (e.g., Network topology and TE Tunnel modules).

Device level modules follow bottom up approach and are mostly technology-specific modules used to realize a service.

2.2. Service and Network Resources Exposure: Service Level Model Decomposition

Service level model defines a service ordered by a customer from an operator. The service can be built from a combination of network elements and protocols configuration which also include various aspects of the underlying network infrastructure, including fucntions/devices and their subsystems, and relevant protocols operating at the link and network layers across multiple device.

2.3. Service Element Configuration Model Composition

To provide service agility (including network management automation), lower level technology-specific models need to be assembled together to provision each involved network function/device and operate the network based on service requirements described in the service level model.

IETF RTGWG working group has already been tasked to define service elements configuration model composition mechanism and develop several composition model such as network instance model, logical network element model and device model.

These models can be used to setup and administrate both virtualized system and physical system.

2.4. A Catalog for YANG Modules

The idea of a catalog is similar to service catalogs in traditional IT environments. Service catalogs serve as a software-based registries of available services with information needed to discover and invoke available services.

The IETF has already tasked to develop a YANG catalog which can be used to manage not only IETF defined modules, but also non-IETF defined ones [I-D.clacla-netmod-model-catalog].

The YANG catalog allows to align IETF work with other SDOs work and prevent duplicated building blocks being developed. It also encourages reusability of common building blocks.

The YANG catalog allows both YANG developers and operators to discover the more mature YANG modules that may be used to automate services operations .

3. IETF YANG Modules: An Overview

  << Customer facing Service Models>>
                                        +-------------+  +-------------+
  +----------------+ +----------------+ |DOTS Data    |  |   I2NSF     |
  |      L3SM      | |     L2SM       | |and Signaling|  |   Customer  |
  |  Service Model | |  Service Model | |  Models     |  | Facing Model|
  +----------------+ +----------------+ +-------------+  +-------------+
  << Resource Facing Models>>
       +------------+  +-------+  +----------------+   +------------+
       |Network Topo|  | Tunnel|  |Path Computation|   |OAM,PM,Alarm|
       |   Models   |  | Models|  | API Models     |   |   Models   |
       +------------+  +-------+  +----------------+   +------------+
<<Network Service and Resource Models>>
<<Network Element Models>>
   <<Composition Models>>
       +-------------+ +---------------+ +----------------+
       |Device Model | |Logical Network| |Network Instance|
       |             | |Element Model  | |   Model        |
       +-------------+ +---------------+ +----------------+

  << Component Models>>
     +-----+   +------+ +---++----+ +----+ |OAM,PM,Alarm|
     | BGP |   | MPLS | |ACL||QoS | |NAT | |   Models   |  .....
     +-----+   +------+ +---++----+ +----+ +------------+

3.1. Network Service and Resource Models

Service and Network Resource Exposure modules define what the "service"/"resource" is. These modules can be classified into two categories:

3.1.1. Customer facing Service Models: Definition and Samples

As described in [RFC8309], the service is some form of connectivity between customer sites and the Internet or between customer sites across the network operator's network and across the Internet.

For example,

The IETF is currently defining three other customer-facing modules: ietf-dots-signal-channel [I-D.ietf-dots-signal-channel] and ietf-dots-data-channel [I-D.ietf-dots-data-channel] and I2NSF Consumer-Facing Interface YANG module [I-D.jeong-i2nsf-consumer-facing-interface-dm]. The first two modules are meant to be used by clients to signal DDoS attacks or to request installing filters for the sake of DDoS mitigation. Those modules do not intervene directly in the configuration of underlying network devices. The third module is required for enabling different users of a given I2NSF system to define, manage, and monitor security policies for specific flows within an administrative domain.

3.1.2. Resource Facing Network Models

Figure 1 shows a set of resource-facing network YANG modules:

                     |                             |
    Topo YANG Models |    Tunnel Service Models    |Resource NM Tool
   ------------------------------------------------|-- ------------
+------------+       |                             |
|Network Top |       |           +-----------+     |       +-------+
|   Model    |       |           | TE Tunnel |     |       | LIME  |
+----+-------+       |           +------+----+     |       | Model |
     |   +--------+  |                  |          |       |/PM/OAM|
     |---+TE Topo |  |         +--------+-+--------+       |  Model|
     |   +--------+  |    +----+---+  +---+----+ +-+-----+ +-------+
     |   +--------+  |    |MPLS-TE |  |RSVP-TE | |SR TE  | +--------+
     +---+L3 Topo |       | Tunnel |  | Tunnel | |Tunnel | |  Alarm |
         +----|---+       +--------+  +--------+ +-------+ |  Model |
    +---------+---------+                                  +--------+
    |         |         |                                +-----------+
+---|---+  +--|---+ +---|-+                              |Path       |
|SR Topo|  |SR TE | |L3 TE|                              |Computation|
| Model |  | Topo | |Topo |                              |API Model  |
+-------+  +------+ +-----+                              +-----------+

Figure 1: Sample Resource Facing Network Models

3.2. Network Element Models

                                     --|Device Model    |
                                     | +----------------+
                                     | +------------------+
                  +---------------+  | |Logical Network   |
                  |               |  --|  Element Mode    |
                  | Architecture  |  | +------------------+
                  |               |  | +----------------------+
                  +-------+-------+  --|Network Instance Mode |
                          |          | +----------------------+
                          |          | +-------------------+
                          |          --|Routing Type Model |
                          |            +-------------------+
  |       |          |           |            |           |       |
+-+-+ +---+---+   +--+-+       +-+-+    +-----+---+   +---+-+     |
|ACL| |Routing|   |MPLS|       |OAM|    |Multicast|   |  PM |  Others
+---+ |-------+   +----+       +---+    +---------+   +-----+
      | +-------+  +----------+ +-------+   +-----+    +-----+
      --|Core   |  |MPLS Basic| |BFD    |   |IGMP |    |TWAMP|
      | |Routing|  +----------+ +-------+   |/MLD |    +-----+
      | +-------+  |MPLS LDP  | |LSP Ping   +-----+    |OWAMP|
      --|BGP    |  +----------+ +-------+   |PIM  |    +-----+
      | +-------+  |MPLS Static |MPLS-TP|   +-----+    |LMAP |
      --|ISIS   |  +----------+ +-------+   |MVPN |    +-----+
      | +-------+                           +-----+
      --|OSPF   |
      | +-------+
      --|RIP    |                                           
      | +-------+
      --|VRRP   |
      | +-------+
      | +-------+
      | +-------+

Network Element models are used to describe how a service can be implemented by activating and tweaking a set of functions (enabled in one or multiple devices) that are involved in the service delivery.

3.2.1. Model Composition Schema Mount

Modularity and extensibility were among the leading design principles of the YANG data modeling language. As a result, the same YANG module can be combined with various sets of other modules and thus form a data model that is tailored to meet the requirements of a specific use case. [I-D.ietf-netmod-schema-mount] defines a mechanism, denoted schema mount, that allows for mounting one data model consisting of any number of YANG modules at a specified location of another (parent) schema.

That capability does not cover design time.

3.2.2. Protocol/Function Configuration Models

[I.D-mks-idr-bgp-yang-model] defines a YANG module for configuring and managing BGP, including protocol, policy, and operational aspects based on data center, carrier and content provider operational requirements.
[I.D-ietf-mpls-base-yang] defines a base model for MPLS which serves as a base framework for configuring and managing an MPLS switching subsystem. It is expected that other MPLS technology YANG models (e.g. MPLS LSP Static, LDP or RSVP-TE models) will augment the MPLS base YANG model.
[I.D-asechoud-netmod-diffserv-model] describes a YANG model of Differentiated Services for configuration and operations.
Access Control List (ACL) is one of the basic elements used to configure device forwarding behavior. It is used in many networking technologies such as Policy Based Routing, Firewalls etc. [I.D-ietf-netmod-acl-model] describes a data model of Access Control List (ACL) basic building blocks.
For the sake of network automation and the need for programming Network Address Translation (NAT) function in particular, a data model for configuring and managing the NAT is essential. [I.D-ietf-opsawg-nat-yang] defines a YANG module for the NAT function.
[I.D-ietf-pim-yang] defines a YANG module that can be used to configure and manage Protocol Independent Multicast (PIM) devices. [I.D-ietf-pim-igmp-mld-yang] defines a YANG module that can be used to configure and manage Internet Group Management Protocol (IGMP) and Multicast Listener Discovery (MLD) devices.

4. Architecture Overview

The architectural considerations and conclusions described in the previous section lead to the architecture described in this section and illustrated in Figure 2.

The interfaces and interactions shown in the figure and labeled (a) through (j) are further described in Section 5.1.

      |Service Requester|
|       | (b)+---(h)------ feedback                               |
|       |  V |                                                    |
|    +--|----V+ +-------------+                                   |
|    |Service&| |   Model     |-----(c)-----------------+         |
| +-->Resource|->Decomposition|                         |         |
| |  |Exposure| |/Composition |                         |         |
| |  +--------+ +-------------+                         |         |
| |        |                                            |         |
| | +------V-----+          +-----------+        +------V------+  |
| | |   Model    |   (e)    |  Path     |  (f)   |    Model    |  |
| | | Translation|--------->|Computation|------->|Configuration|  |
| | +------------+          +-^---------+        +-----(d)-----+  |
| (a)Exposure&Abstraction     |   |                     |         |
| |       --------------------+   |(f)                  V         |
| |       |                       |                               |
| |  +----|------+         +------V----+                          |
| |  |Basic Topo |         |    Path   |                          |
| +--|Collection |     +---|   Setup   |                          |
|    +----^--|---+     |   +-----------+                          |
|         |  |         |                   (h)                    |
|        (a) |  +------V----+Service  +-----------+     (i)       |
|         |  |  |   Topo    | Topo    |  PM/Alarm | Network Opt   |
|         |  +--> Mapping   ------->  | Collection------>         |
|         |     +-----------+         +-----------+               |

Figure 2: Data Model Driven Management

4.1. End-to-End Service Delivery Procedure

4.1.1. Resource Collection and Abstraction (a)

Network Resource such as links, nodes, or terminate-point resources can be collected from the network and aggregated or abstracted to the management system.

These resources can be modelled using network topology model, L3 topology model, L2 topology model, TE topology model, L3 TE topology model, SR TE topology models at different layers.

In some cases, there may have multiple overlay topologies built on top of the same underlay topology, and the underlay topology can be also built from one or more lower layer underlay topology.

The network resources and management objects are exposed in a more abstract way to the management system or customers who (will) order the service from the management system.

The abstract view is likely to be technology-agnostic.

4.1.2. Service Exposure & Abstraction (b)

Service exposure & abstraction is used to capture services offered to customers.

Service abstraction can be used by a customer to request a service (ordering and order handling). One typical example is that a customer can use L3SM service model to request L3VPN service by providing the abstract technical characterization of the intended service. Such L3VPN service describes various aspects of network infrastructure, including devices and their subsystems, and relevant protocols operating at the link and network layers across multiple device. The L3SM service model can be used to interact with the network infrastructure, e.g., configure sites, decide QoS parameters to be applied to each network access within a site, select PEs, CEs, etc.

Service catalogs can be created to expose the various services and the information needed to invoke/order a given service.

YANG modules can be grouped into various service bundles; each service bundle is corresponding to a set of YANG modules that have been released or published. Then, a mapping can be established between service abstraction and service bundles at higher layer and between service bundle and a set of YANG modules at lower layer.

4.1.3. Model Decomposition/Composition (c)

Service abstraction starts with high-level abstractions exposing the business capabilities or capturing customer requirements. Then, it needs to maps them to resource abstraction and specific network technologies.

Therefore, the interaction between service abstraction and resource abstraction or between overlay and underlay is required. For example, in the L3SM service model, we describe VPN service topology including sites relationship, e.g., hub and spoke and any to any, single homed, dual-homed, multi-homed relation between PEs and CEs, but we don't know how this service topology can be mapped into underlying network topology. For detailed interaction, please refer to .

In addition, there is a need to decide on a mapping between service abstraction and underlying specific network technologies. Take L3SM service model as an example, to realize L3VPN service, we need to map L3SM service view defined in Service model into detailed configuration view defined by specific configuration models for network elements, these configuration models include:

These detailed configuration models are further assembled together into service bundle using, e.g., device model, logical network element model or network instance model defined in [I.D-ietf-rtgwg-device-model] [I.D-ietf-rtgwg-lne-model] [I.D-ietf-rtgwg-ni-model] provide the association between an interface and its associated LNE and NI and populate into appropriate devices(e.g., PE and CE).

4.1.4. Model Configuration (d)

Model Configuration is used to provision service or network infrastructure using various configuration models, e.g., use service element models such as BGP, ACL, QoS, Interface model, Network instance models to configure PE and CE device within the site. BGP Policy model is used to establish VPN membership between sites and VPN Service Topology. Traditionally, "push" service element configuration model one by one to the network device and provide association between an interface and each service element configuration model is not efficient.

To automate configuration of the service elements, we first assemble all related service elements models into logical network element model defined in [I.D-ietf-rtgwg-lne-model] and then establish association with an interface and a set of service elements.

In addition, Model configuration can be used to setup tunnels between sites and setup tunnels between PE and CE within the site when tunnels related configuration parameters can be generated from service abstraction.

4.1.5. Model Translation (e)

In L3SM Service Model, the management system will have to determine where to connect each site-network-access of a particular site to the provider network (e.g., PE, aggregation switch). L3SM Service model proposes parameters and constraints that can influence the meshing of the site-network-access.

Nodes used to connect a site may be captured in relevant clauses of a service exposure model (e.g., Customer Nodes Map [RFC7297]).

When Site location is determined, PE and CE device location will be selected. Then we can replace parameters and constraints that can influence the meshing of the site-network-access with specified PE and CE device information associated with site- network-access and generate resource facing VN Overlay Resource model.

This VN Overlay Resource model can be used to calculate node and link resource to Meet service requirements based on Network Topology models collected at step (a).

4.1.6. Path Management (f)

Path Management includes Path computation and Path setup. For example, we can translate L3SM service model into resource facing VN Overlay Resource Model, with selected PE and CE in each site, we can calculate point to point or multipoint end to end path between sites based on VPN Overlay Resource Model.

4.1.7. Overlay and Underlay Interaction (g)

After identifying node and link resources required to meet service requirements, the mapping between overlay topology and underlay topology can be set, e.g., establish an association between VPN service topology defined in customer facing model and underlying network topology defined in I2RS network topology model (e.g., one overlay node is supported by multiple underlay nodes, one overlay link is supported by multiple underlay nodes)and generate end to end VN topology model.

4.1.8. Performance Measurement and Alarm Reporting (h)

Once the mapping between overlay and underlay has been setup, PM and Warning information per link based on end to end VN topology can be collected and report to the management system.

Performance metrics can be collected before instantiating a service, too.

4.1.9. (Continuous) Network Optimization (i)

Operators may use dedicated features to dynamically capture the overall network status and topology to:

4.2. Overlay and Underlay Interaction Usage: Sample Examples

4.2.1. Network Topology Resource Pre-Provision

                      | Management System | (3)(4)(5)

       /     _[CE2]                      _[CE3]                 /
      /    _/  :   \_                  _/  :   \_              /
     /   _/     :    \_              _/     :    \_           /
    /  _/        :     \_          _/        :     \_        /
   /  /           :      \        /           :      \      /
  /[CE1]_________________[PE1] [PE2]_________________[CE4] /
        +---------------------+    +---------------------+"Resource"
       /   [Y5]...           /    / [Z5]______[Z3]      /
      /    /  \  :          /    /  : \_       / :     /
     /    /    \  :        /    /   :   \_    /  :    /
    /    /      \  :      /    /   :      \  /   :   /
   /   [Y4]____[Y1] :    /    /   :       [Z2]   :  /
  +------:-------:---:--+    +---:---------:-----:-+       ^
  vNet1  :        :   :         :          :     :  vNet2  |
         :         :   :       :           :     :         |(1)
         :  +-------:---:-----:------------:-----:-----+   |
         : /       [X1]__:___:___________[X2]   :     /    |
         :/         / \_  : :       _____/ /   :     /     |
         :         /    \_ :  _____/      /   :     /
        /:        /       \: /           /   :     /
       / :       /        [X5]          /   :     /
      /   :     /       __/ \__        /   :     /
     /     :   /    ___/       \__    /   :     /
    /       : / ___/              \  /   :     /
   /        [X4]__________________[X3]..:     /
                       L3 Topology

The following steps are performed to deliver the service within model driven management architecture proposed in this document:

4.2.2. On Demand Network Topology Resource Creation

                      | Management System | (3)(4)(5)

       /     _[CE2]                      _[CE3]                 /
      /    _/  :   \_                  _/  :   \_              /
     /   _/     :    \_              _/     :    \_           /
    /  _/        :     \_          _/        :     \_        /
   /  /           :      \        /           :      \      /
  /[CE1]_________________[PE1] [PE2]_________________[CE4] /
                                                        "Resource"                             ^
         :                                                 |
         :         :   :                                   |(1)
         :  +-------:---:-----:------------:-----:-----+   |
         : /       [X1]__:___  __________[X2]         /    |
         :/         / \_  :         _____/ /         /     |
         :         /    \_ :  _____/      /         /
        /:        /       \: /           /         /
       / :       /        [X5]          /         /
      /   :     /       __/ \__        /         /
     /     :   /    ___/       \__    /         /
    /       : / ___/              \  /         /
   /        [X4]__________________[X3].       /
                       L3 Topology

The following steps are performed to deliver the service within model driven management architecture proposed in this document:

5. Security Considerations

Security considerations specific to each of the technologies and protocols listed in the document are discussed in the specification documents of each of these techniques.

(Potential) security considerations specific to this document are listed below:

6. IANA Considerations

There are no IANA requests or assignments included in this document.

7. Informative References

[I-D.arkko-arch-virtualization] Arkko, J., Tantsura, J., Halpern, J. and B. Varga, "Considerations on Network Virtualization and Slicing", Internet-Draft draft-arkko-arch-virtualization-00, November 2017.
[I-D.asechoud-netmod-diffserv-model] Choudhary, A., Shah, S., Jethanandani, M., Liu, B. and N. Strahle, "YANG Model for Diffserv", Internet-Draft draft-asechoud-netmod-diffserv-model-03, June 2015.
[I-D.clacla-netmod-model-catalog] Clarke, J. and B. Claise, "YANG module for", Internet-Draft draft-clacla-netmod-model-catalog-02, October 2017.
[I-D.ietf-ccamp-alarm-module] Vallin, S. and M. Bjorklund, "YANG Alarm Module", Internet-Draft draft-ietf-ccamp-alarm-module-01, February 2018.
[I-D.ietf-dots-data-channel] Reddy, T., Boucadair, M., Nishizuka, K., Xia, L., Patil, P., Mortensen, A. and N. Teague, "Distributed Denial-of-Service Open Threat Signaling (DOTS) Data Channel Specification", Internet-Draft draft-ietf-dots-data-channel-13, January 2018.
[I-D.ietf-dots-signal-channel] Reddy, T., Boucadair, M., Patil, P., Mortensen, A. and N. Teague, "Distributed Denial-of-Service Open Threat Signaling (DOTS) Signal Channel Specification", Internet-Draft draft-ietf-dots-signal-channel-17, January 2018.
[I-D.ietf-i2rs-yang-l3-topology] Clemm, A., Medved, J., Varga, R., Liu, X., Ananthakrishnan, H. and N. Bahadur, "A YANG Data Model for Layer 3 Topologies", Internet-Draft draft-ietf-i2rs-yang-l3-topology-16, December 2017.
[I-D.ietf-i2rs-yang-network-topo] Clemm, A., Medved, J., Varga, R., Bahadur, N., Ananthakrishnan, H. and X. Liu, "A Data Model for Network Topologies", Internet-Draft draft-ietf-i2rs-yang-network-topo-20, December 2017.
[I-D.ietf-l2sm-l2vpn-service-model] Wen, B., Fioccola, G., Xie, C. and L. Jalil, "A YANG Data Model for L2VPN Service Delivery", Internet-Draft draft-ietf-l2sm-l2vpn-service-model-08, February 2018.
[I-D.ietf-lime-yang-connection-oriented-oam-model] Kumar, D., Wu, Q. and Z. Wang, "Generic YANG Data Model for Connection Oriented Operations, Administration, and Maintenance(OAM) protocols", Internet-Draft draft-ietf-lime-yang-connection-oriented-oam-model-07, February 2018.
[I-D.ietf-lime-yang-connectionless-oam] Kumar, D., Wang, Z., Wu, Q., Rahman, R. and S. Raghavan, "Generic YANG Data Model for the Management of Operations, Administration, and Maintenance (OAM) Protocols that use Connectionless Communications", Internet-Draft draft-ietf-lime-yang-connectionless-oam-18, November 2017.
[I-D.ietf-lime-yang-connectionless-oam-methods] Kumar, D., Wang, Z., Wu, Q., Rahman, R. and S. Raghavan, "Retrieval Methods YANG Data Model for the Management of Operations, Administration, and Maintenance (OAM) Protocols that use Connectionless Communications", Internet-Draft draft-ietf-lime-yang-connectionless-oam-methods-13, November 2017.
[I-D.ietf-mpls-base-yang] Saad, T., Raza, K., Gandhi, R., Liu, X. and V. Beeram, "A YANG Data Model for MPLS Base", Internet-Draft draft-ietf-mpls-base-yang-06, February 2018.
[I-D.ietf-netmod-acl-model] Jethanandani, M., Huang, L., Agarwal, S. and D. Blair, "Network Access Control List (ACL) YANG Data Model", Internet-Draft draft-ietf-netmod-acl-model-16, February 2018.
[I-D.ietf-netmod-schema-mount] Bjorklund, M. and L. Lhotka, "YANG Schema Mount", Internet-Draft draft-ietf-netmod-schema-mount-08, October 2017.
[I-D.ietf-opsawg-nat-yang] Boucadair, M., Sivakumar, S., Jacquenet, C., Vinapamula, S. and Q. Wu, "A YANG Module for Network Address Translation (NAT) and Network Prefix Translation (NPT)", Internet-Draft draft-ietf-opsawg-nat-yang-13, February 2018.
[I-D.ietf-pim-igmp-mld-yang] Liu, X., Guo, F., Sivakumar, M., McAllister, P. and A. Peter, "A YANG data model for Internet Group Management Protocol (IGMP) and Multicast Listener Discovery (MLD)", Internet-Draft draft-ietf-pim-igmp-mld-yang-06, October 2017.
[I-D.ietf-pim-yang] Liu, X., McAllister, P., Peter, A., Sivakumar, M., Liu, Y. and f. hu, "A YANG Data Model for Protocol Independent Multicast (PIM)", Internet-Draft draft-ietf-pim-yang-15, February 2018.
[I-D.ietf-rtgwg-device-model] Lindem, A., Berger, L., Bogdanovic, D. and C. Hopps, "Network Device YANG Logical Organization", Internet-Draft draft-ietf-rtgwg-device-model-02, March 2017.
[I-D.ietf-rtgwg-lne-model] Berger, L., Hopps, C., Lindem, A., Bogdanovic, D. and X. Liu, "YANG Model for Logical Network Elements", Internet-Draft draft-ietf-rtgwg-lne-model-09, March 2018.
[I-D.ietf-rtgwg-ni-model] Berger, L., Hopps, C., Lindem, A., Bogdanovic, D. and X. Liu, "YANG Model for Network Instances", Internet-Draft draft-ietf-rtgwg-ni-model-11, March 2018.
[I-D.ietf-teas-yang-path-computation] Busi, I., Belotti, S., Lopezalvarez, V., Dios, O.,, a., Shi, Y., Vilata, R., Sethuraman, K., Scharf, M. and D. Ceccarelli, "Yang model for requesting Path Computation", Internet-Draft draft-ietf-teas-yang-path-computation-00, November 2017.
[I-D.ietf-teas-yang-rsvp-te] Beeram, V., Saad, T., Gandhi, R., Liu, X., Bryskin, I. and H. Shah, "A YANG Data Model for RSVP-TE", Internet-Draft draft-ietf-teas-yang-rsvp-te-03, February 2018.
[I-D.ietf-teas-yang-te] Saad, T., Gandhi, R., Liu, X., Beeram, V., Shah, H. and I. Bryskin, "A YANG Data Model for Traffic Engineering Tunnels and Interfaces", Internet-Draft draft-ietf-teas-yang-te-12, February 2018.
[I-D.ietf-teas-yang-te-topo] Liu, X., Bryskin, I., Beeram, V., Saad, T., Shah, H. and O. Dios, "YANG Data Model for Traffic Engineering (TE) Topologies", Internet-Draft draft-ietf-teas-yang-te-topo-15, February 2018.
[I-D.jeong-i2nsf-consumer-facing-interface-dm] Jeong, J., Kim, E., Ahn, T., Kumar, R. and S. Hares, "I2NSF Consumer-Facing Interface YANG Data Model", Internet-Draft draft-jeong-i2nsf-consumer-facing-interface-dm-05, November 2017.
[I-D.liu-teas-yang-l3-te-topo] Liu, X., Bryskin, I., Beeram, V., Saad, T., Shah, H. and O. Dios, "YANG Data Model for Layer 3 TE Topologies", Internet-Draft draft-liu-teas-yang-l3-te-topo-05, October 2017.
[I-D.liu-teas-yang-sr-te-topo] Liu, X., Bryskin, I., Beeram, V., Saad, T., Shah, H. and S. Litkowski, "YANG Data Model for SR and SR TE Topologies", Internet-Draft draft-liu-teas-yang-sr-te-topo-04, October 2017.
[I-D.mks-idr-bgp-yang-model] Patel, K., Jethanandani, M. and S. Hares, "BGP YANG Model", Internet-Draft draft-mks-idr-bgp-yang-model-01, November 2017.
[RFC7149] Boucadair, M. and C. Jacquenet, "Software-Defined Networking: A Perspective from within a Service Provider Environment", RFC 7149, DOI 10.17487/RFC7149, March 2014.
[RFC7297] Boucadair, M., Jacquenet, C. and N. Wang, "IP Connectivity Provisioning Profile (CPP)", RFC 7297, DOI 10.17487/RFC7297, July 2014.
[RFC8199] Bogdanovic, D., Claise, B. and C. Moberg, "YANG Module Classification", RFC 8199, DOI 10.17487/RFC8199, July 2017.
[RFC8299] Wu, Q., Litkowski, S., Tomotaki, L. and K. Ogaki, "YANG Data Model for L3VPN Service Delivery", RFC 8299, DOI 10.17487/RFC8299, January 2018.
[RFC8309] Wu, Q., Liu, W. and A. Farrel, "Service Models Explained", RFC 8309, DOI 10.17487/RFC8309, January 2018.

Authors' Addresses

Qin Wu Huawei 101 Software Avenue, Yuhua District Nanjing, Jiangsu 210012 China EMail:
Mohamed Boucadair Orange Rennes 35000 France EMail: