A Framework for Automating Service and Network Management with YANG
draft-ietf-opsawg-model-automation-framework-06
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft that was ultimately published as RFC 8969.
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|---|---|---|---|
| Authors | Qin Wu , Mohamed Boucadair , Diego Lopez , Chongfeng Xie , Liang Geng | ||
| Last updated | 2020-10-08 (Latest revision 2020-09-22) | ||
| Replaces | draft-wu-model-driven-management-virtualization | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Formats | |||
| Reviews |
TSVART Last Call review
by Tommy Pauly
Ready w/issues
SECDIR Last Call review
by Christian Huitema
Has issues
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| Additional resources | Mailing list discussion | ||
| Stream | WG state | Submitted to IESG for Publication | |
| Document shepherd | Adrian Farrel | ||
| Shepherd write-up | Show Last changed 2020-06-16 | ||
| IESG | IESG state | Became RFC 8969 (Informational) | |
| Consensus boilerplate | Unknown | ||
| Telechat date | (None) | ||
| Responsible AD | Robert Wilton | ||
| Send notices to | Adrian Farrel <adrian@olddog.co.uk> | ||
| IANA | IANA review state | IANA OK - No Actions Needed |
draft-ietf-opsawg-model-automation-framework-06
4.1.1. Service Exposure A service in the context of this document (sometimes called, Network Service) is some form of connectivity between customer sites and the Internet or between customer sites across the operator's network and across the Internet. Service exposure is used to capture services offered to customers (ordering and order handling). One typical example is that a customer can use a L3VPN Service Model (L3SM) to request L3VPN service by providing the abstract technical characterization of the intended service between customer sites. Service Model catalogs can be created along to expose the various services and the information needed to invoke/order a given service. 4.1.2. Service Creation/Modification A customer is usually unaware of the technology that the network operator has available to deliver the service, so the customer does not make requests specific to the underlying technology but is limited to making requests specific to the service that is to be delivered. This service request can be issued using a Service Model. Upon receiving a service request, and assuming that appropriate authentication and authorization checks have been made, the service orchestrator/management system should verify whether the service requirements in the service request can be met (i.e., whether there is sufficient resources that can be allocated with the requested guarantees). If the request is accepted, the service orchestrator/management system maps such service request to its view. This view can be described as a technology specific network model or a set of technology specific Device Models and this mapping may include a choice of which networks and technologies to use depending on which service features have been requested. In addition, a customer may require to change the underlying network infrastructure to adapt to new customer's needs and service requirements. This service modification can be issued following the same Service Model used by the service request. 4.1.3. Service Optimization Service optimization is a technique that gets the configuration of the network updated due to network changes, incidents mitigation, or new service requirements. One typical example is once a tunnel or a Wu, et al. Expires March 26, 2021 [Page 13] Internet-Draft Service and Network Management Automation September 2020 VPN is setup, Performance monitoring information or telemetry information per tunnel (or per VPN) can be collected and fed into the management system. If the network performance doesn't meet the service requirements, the management system can create new VPN policies capturing network service requirements and populate them into the network. Both network performance information and policies can be modelled using YANG. With Policy-based management, self-configuration and self-optimization behavior can be specified and implemented. 4.1.4. Service Diagnosis Operations, Administration, and Maintenance (OAM) are important networking functions for service diagnosis that allow network operators to: o monitor network communications (i.e., reachability verification and Continuity Check) o troubleshoot failures (i.e., fault verification and localization) o monitor service-level agreements and performance (i.e., performance management) When the network is down, service diagnosis should be in place to pinpoint the problem and provide recommendations (or instructions) for the network recovery. The service diagnosis information can be modelled as technology- independent Remote Procedure Call (RPC) operations for OAM protocols and technology-independent abstraction of key OAM constructs for OAM protocols [RFC8531][RFC8533]. These models can be used to provide consistent configuration, reporting, and presentation for the OAM mechanisms used to manage the network. 4.1.5. Service Decommission Service decommission allows a customer to stop the service by removing the service from active status and thus releasing the network resources that were allocated to the service. Customers can also use the Service Model to withdraw the registration to a service. 4.2. Service Fullfillment Management Procedure Wu, et al. Expires March 26, 2021 [Page 14] Internet-Draft Service and Network Management Automation September 2020 4.2.1. Intended Configuration Provision Intended configuration at the device level is derived from Network Models at the network level or Service Model at the service level and represents the configuration that the system attempts to apply. Take L3SM as a Service Model example to deliver a L3VPN service, we need to map the L3VPN service view defined in the Service Model into detailed intended configuration view defined by specific configuration models for network elements, configuration information includes: o Virtual Routing and Forwarding (VRF) definition, including VPN policy expression o Physical Interface(s) o IP layer (IPv4, IPv6) o QoS features such as classification, profiles, etc. o Routing protocols: support of configuration of all protocols listed in a service request, as well as routing policies associated with those protocols. o Multicast support o Address sharing (e.g., NAT) o Security These specific configuration models can be used to configure Provider Edge (PE) and Customer Edge (CE) devices within a site, e.g., a BGP policy model can be used to establish VPN membership between sites and VPN Service Topology. 4.2.2. Configuration Validation Configuration validation is used to validate intended configuration and ensure the configuration take effect. For example, a customer creates an interface "eth-0/0/0" but the interface does not physically exist at this point, then configuration data appears in the <intended> status but does not appear in <operational> datastore. Wu, et al. Expires March 26, 2021 [Page 15] Internet-Draft Service and Network Management Automation September 2020 4.2.3. Performance Monitoring/Model-driven Telemetry When configuration is in effect in the device, <operational> datastore holds the complete operational state of the device including learned, system, default configuration, and system state. However, the configurations and state of a particular device does not have the visibility to the whole network or information of the flow packets are going to take through the entire network. Therefore it becomes more difficult to operate the network without understanding the current status of the network. The management system should subscribe to updates of a YANG datastore in all the network devices for performance monitoring purpose and build a full topological visibility of the network by aggregating (and filtering) these operational state from different sources. 4.2.4. Fault Diagnostic When configuration is in effect in the device, some devices may be mis-configured (e.g.,device links are not consistent in both sides of the network connection), network resources be mis-allocated and services may be negatively affected without knowing what is going on in the network. Technology-dependent nodes and RPC commands are defined in technology-specific YANG data models which can use and extend the base model described in Section 4.1.4 to deal with these issues. These RPC commands received in the technology-dependent node can be used to trigger technology-specific OAM message exchanges for fault verification and fault isolation For example, TRILL Multicast Tree Verification (MTV) RPC command [I-D.ietf-trill-yang-oam] can be used to trigger Multi-Destination Tree Verification Message defined in [RFC7455] to verify TRILL distribution tree integrity. 4.3. Multi-Layer/Multi-Domain Service Mapping Multi-layer/Multi-domain Service Mapping allows to map an end-to-end abstract view of the service segmented at different layers or different administrative domains into domain-specific view. One example is to map service parameters in L3VPN service model into configuration parameters such as Route Distinguisher (RD), Route Target (RT), and VRF in L3VPN network model. Another example is to map service parameters in L3VPN service model into Traffic Engineered (TE) tunnel parameter (e.g., Tunnel ID) in TE model and Virtual Network (VN) parameters (e.g., Access Point (AP) Wu, et al. Expires March 26, 2021 [Page 16] Internet-Draft Service and Network Management Automation September 2020 list, VN members) in the YANG data model for VN operation [I-D.ietf-teas-actn-vn-yang]. 4.4. Service Decomposing Service Decomposing allows to decompose service model at the service level or network model at the network level into a set of device/ function models at the device level. These Device Models may be tied to specific device types or classified into a collection of related YANG modules based on service types and features offered, and load at the implementation time before configuration is loaded and validated. 5. YANG Data Model Integration Examples The following subsections provides some YANG data models integration examples. 5.1. L2VPN/L3VPN Service Delivery In reference to Figure 5, the following steps are performed to deliver the L3VPN service within the network management automation architecture defined in this document: 1. The Customer requests to create two sites (as per service creation operation in Section 4.2.1) relying upon a L3SM Service model with each having one network access connectivity, for example: * Site A: Network-Access A, Link Capacity = 20 Mbps, for class "foo", guaranteed-capacity-percent = 10, average-One-Way-Delay = 70 ms. * Site B: Network-Access B, Link Capacity = 30 Mbps, for class "foo1", guaranteed-capacity-percent = 15, average-One-Way- Delay = 60 ms. 2. The Orchestrator extracts the service parameters from the L3SM model. Then, it uses them as input to translate ("service mapping operation" in Section 4.4) them into an orchestrated configuration of network elements (e.g., RD, RT, VRF) that are part of the L3VPN Network YANG Model specified in [I-D.ietf-opsawg-l3sm-l3nm]. 3. The Controller takes orchestrated configuration parameters in the L3NM network model and translates them into orchestrated ("service decomposing operation" in ) configuration of network elements that are part of, e.g., BGP, QoS, Network Instance model, IP management, and interface models. Wu, et al. Expires March 26, 2021 [Page 17] Internet-Draft Service and Network Management Automation September 2020 [I-D.ogondio-opsawg-uni-topology] can be used for representing, managing, and controlling the User Network Interface (UNI) topology. L3SM | Service | Model | +----------------------+--------------------------+ | +--------V--------+ | | | Service Mapping | | | +--------+--------+ | | Orchestrator | | +----------------------+--------------------------+ L3NM | ^ UNI Topology Model Network| | Model | | +----------------------+--------------------------+ | +----------V-----------+ | | | Service Decomposing | | | +---++--------------++-+ | | || || | | Controller || || | +---------------++--------------++----------------+ || || || BGP, || || QoS, || || Interface, || +------------+| NI, |+--------------+ | | IP | | +--+--+ +--+--+ +--+--+ +--+--+ | CE1 +-------+ PE1 | | PE2 +---------+ CE2 | +-----+ +-----+ +-----+ +-----+ Figure 5: L3VPN Service Delivery Example (Current) L3NM inherits some of data elements from the L3SM. Nevertheless, the L3NM does not expose some information to the above layer such as the capabilities of an underlying network (which can be used to drive service order handling) or notifications (to notify subscribers about specific events or degradations as per agreed SLAs). Some of this information can be provided using, e.g., [I-D.www-bess-yang-vpn-service-pm]. A target overall model is depicted in Figure 6. Wu, et al. Expires March 26, 2021 [Page 18] Internet-Draft Service and Network Management Automation September 2020 L3SM | ^ Service | | Notifications Model | | +----------------------+--------------------------+ | +--------V--------+ | | | Service Mapping | | | +--------+--------+ | | Orchestrator | | +----------------------+--------------------------+ L3NM | ^ UNI Topology Model Network| | L3NM Notifications Model | | L3NM Capabilities +----------------------+--------------------------+ | +----------V-----------+ | | | Service Decomposing | | | +---++--------------++-+ | | || || | | Controller || || | +---------------++--------------++----------------+ || || || BGP, || || QoS, || || Interface, || +------------+| NI, |+--------------+ | | IP | | +--+--+ +--+--+ +--+--+ +--+--+ | CE1 +-------+ PE1 | | PE2 +---------+ CE2 | +-----+ +-----+ +-----+ +-----+ Figure 6: L3VPN Service Delivery Example (Target) Note that a similar analysis can be performed for Layer 2 VPNs (L2VPNs). A L2VPN Service Model (L2SM) is defined in [RFC8466], while the L2VPN Network YANG Model (L2NM) is specified in [I-D.ietf-opsawg-l2nm]. 5.2. VN Lifecycle Management In reference to Figure 7, the following steps are performed to deliver the VN service within the network management automation architecture defined in this document: 1. Customer requests (service exposure operation in Section 4.1.1) to create 'VN' based on Access point, association between VN and Access point, VN member defined in the VN YANG module. 2. The orchestrator creates the single abstract node topology based on the information captured in an VN YANG module. Wu, et al. Expires March 26, 2021 [Page 19] Internet-Draft Service and Network Management Automation September 2020 3. The Customer exchanges connectivity-matrix on abstract node and explicit path using TE topology model with the orchestrator. This information can be used to instantiate VN and setup tunnels between source and destination endpoints (service creation operation in Section 4.1.2). 4. The telemetry model which augments the VN model and corresponding TE tunnel model can be used to subscribe to performance measurement data and notify all the parameter changes and network performance change related to VN topology or Tunnel [I-D.ietf-teas-actn-pm-telemetry-autonomics] and provide service assurance (service optimization operation in Section 4.1.3). | VN | Service | Model | +----------------------|--------------------------+ | Orchestrator | | | +--------V--------+ | | | Service Mapping | | | +-----------------+ | +----------------------+--------------------^-----+ TE | Telemetry Tunnel | Model Model | | +----------------------V--------------------+-----+ | Controller | | | +-------------------------------------------------+ +-----+ +-----+ +-----+ +-----+ | CE1 +------+ PE1 | | PE2 +------+ CE2 | +-----+ +-----+ +-----+ +-----+ Figure 7: A VN Service Delivery Example 5.3. Event-based Telemetry in the Device Self Management In reference to Figure 8, the following steps are performed to monitor state changes of managed objects or resources in a network device and provide device self-management within the network management automation architecture defined in this document: 1. To control which state a network device should be in or is allowed to be in at any given time, a set of conditions and actions are defined and correlated with network events (e.g., allow the NETCONF server to send updates only when the value Wu, et al. Expires March 26, 2021 [Page 20] Internet-Draft Service and Network Management Automation September 2020 exceeds a certain threshold for the first time, but not again until the threshold is cleared), which constitute ECA policy or an event-driven policy control logic that can be executed on the device (e.g., [I-D.wwx-netmod-event-yang]). 2. To provide rapid autonomic response that can exhibit self- management properties, the controller pushes the ECA policy to the network device and delegates network control logic to the network device. 3. The network device uses the ECA model to subscribe to the event source, e.g., an event stream or datastore state data conveyed to the server via YANG Push subscription, monitors state parameters, and takes simple and instant actions when associated event condition on state parameters is met. ECA notifications can be generated as the result of actions based on event stream subscription or datastore subscription (model-driven telemetry operation discussed in Section 4.2.3). +----------------+ | <----+ | Controller | | +-------+--------+ | | | | | ECA | | ECA Model | | Notification | | | | +------------V-------------+-----+ |Device | | | +-------+ +---------+ +--+---+ | | | Event +-> Event +->Event | | | | Source| |Condition| |Action| | | +-------+ +---------+ +------+ | +--------------------------------+ Figure 8: Event-based Telemetry 6. Security Considerations The YANG modules cited in this document define schema for data that are designed to be accessed via network management protocols such as NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer is the secure transport layer, and the mandatory-to-implement secure transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer is HTTPS, and the mandatory-to-implement secure transport is TLS [RFC8446]. Wu, et al. Expires March 26, 2021 [Page 21] Internet-Draft Service and Network Management Automation September 2020 The NETCONF access control model [RFC8341] provides the means to restrict access for particular NETCONF or RESTCONF users to a preconfigured subset of all available NETCONF or RESTCONF protocol operations and content. Security considerations specific to each of the technologies and protocols listed in the document are discussed in the specification documents of each of these protocols. Security considerations specific to this document are listed below: o Create forwarding loops by mis-configuring the underlying network. o Leak sensitive information: special care should be considered when translating between the various layers in Section 4 or when aggregating data retrieved from various sources. The network operator must enforce means to protect privacy-related information included in cutsomer-facing models. o Some Service Models may include a traffic isolation clause, appropriate technology-specific actions must be enforced to avoid that traffic is accessible to non-authorized parties. 7. IANA Considerations There are no IANA requests or assignments included in this document. 8. Acknowledgements Thanks to Joe Clark, Greg Mirsky, Shunsuke Homma, Brian Carpenter, and Adrian Farrel for the review. Many thanks to Robert Wilton for the detailed AD review. 9. Contributors Wu, et al. Expires March 26, 2021 [Page 22] Internet-Draft Service and Network Management Automation September 2020 Christian Jacquenet Orange Rennes, 35000 France Email: Christian.jacquenet@orange.com Luis Miguel Contreras Murillo Telifonica Email: luismiguel.contrerasmurillo@telefonica.com Oscar Gonzalez de Dios Telefonica Madrid ES Email: oscar.gonzalezdedios@telefonica.com Weiqiang Cheng China Mobile Email: chengweiqiang@chinamobile.com Young Lee Sung Kyun Kwan University Email: younglee.tx@gmail.com 10. References 10.1. Normative References [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., and A. Bierman, Ed., "Network Configuration Protocol (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011, <https://www.rfc-editor.org/info/rfc6241>. [RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011, <https://www.rfc-editor.org/info/rfc6242>. [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016, <https://www.rfc-editor.org/info/rfc7950>. [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, <https://www.rfc-editor.org/info/rfc8040>. Wu, et al. Expires March 26, 2021 [Page 23] Internet-Draft Service and Network Management Automation September 2020 [RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, March 2018, <https://www.rfc-editor.org/info/rfc8341>. [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, <https://www.rfc-editor.org/info/rfc8446>. 10.2. Informative References [I-D.clacla-netmod-model-catalog] Clarke, J. and B. Claise, "YANG module for yangcatalog.org", draft-clacla-netmod-model-catalog-03 (work in progress), April 2018. [I-D.ietf-bess-evpn-yang] Brissette, P., Shah, H., Hussain, I., Tiruveedhula, K., and J. Rabadan, "Yang Data Model for EVPN", draft-ietf- bess-evpn-yang-07 (work in progress), March 2019. [I-D.ietf-bess-l2vpn-yang] Shah, H., Brissette, P., Chen, I., Hussain, I., Wen, B., and K. Tiruveedhula, "YANG Data Model for MPLS-based L2VPN", draft-ietf-bess-l2vpn-yang-10 (work in progress), July 2019. [I-D.ietf-bess-l3vpn-yang] Jain, D., Patel, K., Brissette, P., Li, Z., Zhuang, S., Liu, X., Haas, J., Esale, S., and B. Wen, "Yang Data Model for BGP/MPLS L3 VPNs", draft-ietf-bess-l3vpn-yang-04 (work in progress), October 2018. [I-D.ietf-bess-mvpn-yang] Liu, Y., Guo, F., Litkowski, S., Liu, X., Kebler, R., and M. Sivakumar, "Yang Data Model for Multicast in MPLS/BGP IP VPNs", draft-ietf-bess-mvpn-yang-04 (work in progress), June 2020. [I-D.ietf-bfd-yang] Rahman, R., Zheng, L., Jethanandani, M., Pallagatti, S., and G. Mirsky, "YANG Data Model for Bidirectional Forwarding Detection (BFD)", draft-ietf-bfd-yang-17 (work in progress), August 2018. Wu, et al. Expires March 26, 2021 [Page 24] Internet-Draft Service and Network Management Automation September 2020 [I-D.ietf-i2rs-yang-l2-network-topology] Dong, J., Wei, X., WU, Q., Boucadair, M., and A. Liu, "A YANG Data Model for Layer 2 Network Topologies", draft- ietf-i2rs-yang-l2-network-topology-17 (work in progress), August 2020. [I-D.ietf-idr-bgp-model] Jethanandani, M., Patel, K., Hares, S., and J. Haas, "BGP YANG Model for Service Provider Networks", draft-ietf-idr- bgp-model-09 (work in progress), June 2020. [I-D.ietf-ippm-capacity-metric-method] Morton, A., Geib, R., and L. Ciavattone, "Metrics and Methods for IP Capacity", draft-ietf-ippm-capacity-metric- method-03 (work in progress), August 2020. [I-D.ietf-ippm-stamp-yang] Mirsky, G., Xiao, M., and W. Luo, "Simple Two-way Active Measurement Protocol (STAMP) Data Model", draft-ietf-ippm- stamp-yang-05 (work in progress), October 2019. [I-D.ietf-ippm-twamp-yang] Civil, R., Morton, A., Rahman, R., Jethanandani, M., and K. Pentikousis, "Two-Way Active Measurement Protocol (TWAMP) Data Model", draft-ietf-ippm-twamp-yang-13 (work in progress), July 2018. [I-D.ietf-mpls-base-yang] Saad, T., Raza, K., Gandhi, R., Liu, X., and V. Beeram, "A YANG Data Model for MPLS Base", draft-ietf-mpls-base- yang-15 (work in progress), August 2020. [I-D.ietf-netmod-module-tags] Hopps, C., Berger, L., and D. Bogdanovic, "YANG Module Tags", draft-ietf-netmod-module-tags-10 (work in progress), February 2020. [I-D.ietf-opsawg-l2nm] barguil, s., Dios, O., Boucadair, M., Munoz, L., Jalil, L., and J. Ma, "A Layer 2 VPN Network YANG Model", draft- ietf-opsawg-l2nm-00 (work in progress), July 2020. [I-D.ietf-opsawg-l3sm-l3nm] barguil, s., Dios, O., Boucadair, M., Munoz, L., and A. Aguado, "A Layer 3 VPN Network YANG Model", draft-ietf- opsawg-l3sm-l3nm-03 (work in progress), April 2020. Wu, et al. Expires March 26, 2021 [Page 25] Internet-Draft Service and Network Management Automation September 2020 [I-D.ietf-pim-igmp-mld-snooping-yang] Zhao, H., Liu, X., Liu, Y., Sivakumar, M., and A. Peter, "A Yang Data Model for IGMP and MLD Snooping", draft-ietf- pim-igmp-mld-snooping-yang-18 (work in progress), August 2020. [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)", draft-ietf-pim-yang-17 (work in progress), May 2018. [I-D.ietf-rtgwg-policy-model] Qu, Y., Tantsura, J., Lindem, A., and X. Liu, "A YANG Data Model for Routing Policy Management", draft-ietf-rtgwg- policy-model-21 (work in progress), September 2020. [I-D.ietf-rtgwg-qos-model] Choudhary, A., Jethanandani, M., Strahle, N., Aries, E., and I. Chen, "YANG Model for QoS", draft-ietf-rtgwg-qos- model-02 (work in progress), July 2020. [I-D.ietf-spring-sr-yang] Litkowski, S., Qu, Y., Lindem, A., Sarkar, P., and J. Tantsura, "YANG Data Model for Segment Routing", draft- ietf-spring-sr-yang-22 (work in progress), August 2020. [I-D.ietf-teas-actn-pm-telemetry-autonomics] Lee, Y., Dhody, D., Karunanithi, S., Vilata, R., King, D., and D. Ceccarelli, "YANG models for VN/TE Performance Monitoring Telemetry and Scaling Intent Autonomics", draft-ietf-teas-actn-pm-telemetry-autonomics-03 (work in progress), July 2020. [I-D.ietf-teas-actn-vn-yang] Lee, Y., Dhody, D., Ceccarelli, D., Bryskin, I., and B. Yoon, "A YANG Data Model for VN Operation", draft-ietf- teas-actn-vn-yang-09 (work in progress), July 2020. [I-D.ietf-teas-yang-path-computation] Busi, I., Belotti, S., Lopezalvarez, V., Sharma, A., and Y. Shi, "Yang model for requesting Path Computation", draft-ietf-teas-yang-path-computation-10 (work in progress), July 2020. Wu, et al. Expires March 26, 2021 [Page 26] Internet-Draft Service and Network Management Automation September 2020 [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 Protocol", draft-ietf-teas-yang-rsvp-te-08 (work in progress), March 2020. [I-D.ietf-teas-yang-te] Saad, T., Gandhi, R., Liu, X., Beeram, V., and I. Bryskin, "A YANG Data Model for Traffic Engineering Tunnels, Label Switched Paths and Interfaces", draft-ietf-teas-yang-te-25 (work in progress), July 2020. [I-D.ietf-trill-yang-oam] Kumar, D., Senevirathne, T., Finn, N., Salam, S., Xia, L., and H. Weiguo, "YANG Data Model for TRILL Operations, Administration, and Maintenance (OAM)", draft-ietf-trill- yang-oam-05 (work in progress), March 2017. [I-D.ogondio-opsawg-uni-topology] Dios, O., barguil, s., WU, Q., and M. Boucadair, "A YANG Model for User-Network Interface (UNI) Topologies", draft- ogondio-opsawg-uni-topology-01 (work in progress), April 2020. [I-D.www-bess-yang-vpn-service-pm] WU, Q., Boucadair, M., Dios, O., Wen, B., Liu, C., and H. Xu, "A YANG Model for Network and VPN Service Performance Monitoring", draft-www-bess-yang-vpn-service-pm-06 (work in progress), April 2020. [I-D.wwx-netmod-event-yang] Bierman, A., WU, Q., Bryskin, I., Birkholz, H., Liu, X., and B. Claise, "A YANG Data model for ECA Policy Management", draft-wwx-netmod-event-yang-09 (work in progress), July 2020. [RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February 2006, <https://www.rfc-editor.org/info/rfc4364>. [RFC4664] Andersson, L., Ed. and E. Rosen, Ed., "Framework for Layer 2 Virtual Private Networks (L2VPNs)", RFC 4664, DOI 10.17487/RFC4664, September 2006, <https://www.rfc-editor.org/info/rfc4664>. Wu, et al. Expires March 26, 2021 [Page 27] Internet-Draft Service and Network Management Automation September 2020 [RFC4761] Kompella, K., Ed. and Y. Rekhter, Ed., "Virtual Private LAN Service (VPLS) Using BGP for Auto-Discovery and Signaling", RFC 4761, DOI 10.17487/RFC4761, January 2007, <https://www.rfc-editor.org/info/rfc4761>. [RFC4762] Lasserre, M., Ed. and V. Kompella, Ed., "Virtual Private LAN Service (VPLS) Using Label Distribution Protocol (LDP) Signaling", RFC 4762, DOI 10.17487/RFC4762, January 2007, <https://www.rfc-editor.org/info/rfc4762>. [RFC5136] Chimento, P. and J. Ishac, "Defining Network Capacity", RFC 5136, DOI 10.17487/RFC5136, February 2008, <https://www.rfc-editor.org/info/rfc5136>. [RFC5486] Malas, D., Ed. and D. Meyer, Ed., "Session Peering for Multimedia Interconnect (SPEERMINT) Terminology", RFC 5486, DOI 10.17487/RFC5486, March 2009, <https://www.rfc-editor.org/info/rfc5486>. [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010, <https://www.rfc-editor.org/info/rfc5880>. [RFC6406] Malas, D., Ed. and J. Livingood, Ed., "Session PEERing for Multimedia INTerconnect (SPEERMINT) Architecture", RFC 6406, DOI 10.17487/RFC6406, November 2011, <https://www.rfc-editor.org/info/rfc6406>. [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, <https://www.rfc-editor.org/info/rfc7149>. [RFC7224] Bjorklund, M., "IANA Interface Type YANG Module", RFC 7224, DOI 10.17487/RFC7224, May 2014, <https://www.rfc-editor.org/info/rfc7224>. [RFC7276] Mizrahi, T., Sprecher, N., Bellagamba, E., and Y. Weingarten, "An Overview of Operations, Administration, and Maintenance (OAM) Tools", RFC 7276, DOI 10.17487/RFC7276, June 2014, <https://www.rfc-editor.org/info/rfc7276>. [RFC7297] Boucadair, M., Jacquenet, C., and N. Wang, "IP Connectivity Provisioning Profile (CPP)", RFC 7297, DOI 10.17487/RFC7297, July 2014, <https://www.rfc-editor.org/info/rfc7297>. Wu, et al. Expires March 26, 2021 [Page 28] Internet-Draft Service and Network Management Automation September 2020 [RFC7317] Bierman, A. and M. Bjorklund, "A YANG Data Model for System Management", RFC 7317, DOI 10.17487/RFC7317, August 2014, <https://www.rfc-editor.org/info/rfc7317>. [RFC7455] Senevirathne, T., Finn, N., Salam, S., Kumar, D., Eastlake 3rd, D., Aldrin, S., and Y. Li, "Transparent Interconnection of Lots of Links (TRILL): Fault Management", RFC 7455, DOI 10.17487/RFC7455, March 2015, <https://www.rfc-editor.org/info/rfc7455>. [RFC7679] Almes, G., Kalidindi, S., Zekauskas, M., and A. Morton, Ed., "A One-Way Delay Metric for IP Performance Metrics (IPPM)", STD 81, RFC 7679, DOI 10.17487/RFC7679, January 2016, <https://www.rfc-editor.org/info/rfc7679>. [RFC7680] Almes, G., Kalidindi, S., Zekauskas, M., and A. Morton, Ed., "A One-Way Loss Metric for IP Performance Metrics (IPPM)", STD 82, RFC 7680, DOI 10.17487/RFC7680, January 2016, <https://www.rfc-editor.org/info/rfc7680>. [RFC8077] Martini, L., Ed. and G. Heron, Ed., "Pseudowire Setup and Maintenance Using the Label Distribution Protocol (LDP)", STD 84, RFC 8077, DOI 10.17487/RFC8077, February 2017, <https://www.rfc-editor.org/info/rfc8077>. [RFC8194] Schoenwaelder, J. and V. Bajpai, "A YANG Data Model for LMAP Measurement Agents", RFC 8194, DOI 10.17487/RFC8194, August 2017, <https://www.rfc-editor.org/info/rfc8194>. [RFC8199] Bogdanovic, D., Claise, B., and C. Moberg, "YANG Module Classification", RFC 8199, DOI 10.17487/RFC8199, July 2017, <https://www.rfc-editor.org/info/rfc8199>. [RFC8299] Wu, Q., Ed., Litkowski, S., Tomotaki, L., and K. Ogaki, "YANG Data Model for L3VPN Service Delivery", RFC 8299, DOI 10.17487/RFC8299, January 2018, <https://www.rfc-editor.org/info/rfc8299>. [RFC8309] Wu, Q., Liu, W., and A. Farrel, "Service Models Explained", RFC 8309, DOI 10.17487/RFC8309, January 2018, <https://www.rfc-editor.org/info/rfc8309>. [RFC8343] Bjorklund, M., "A YANG Data Model for Interface Management", RFC 8343, DOI 10.17487/RFC8343, March 2018, <https://www.rfc-editor.org/info/rfc8343>. Wu, et al. Expires March 26, 2021 [Page 29] Internet-Draft Service and Network Management Automation September 2020 [RFC8345] Clemm, A., Medved, J., Varga, R., Bahadur, N., Ananthakrishnan, H., and X. Liu, "A YANG Data Model for Network Topologies", RFC 8345, DOI 10.17487/RFC8345, March 2018, <https://www.rfc-editor.org/info/rfc8345>. [RFC8346] Clemm, A., Medved, J., Varga, R., Liu, X., Ananthakrishnan, H., and N. Bahadur, "A YANG Data Model for Layer 3 Topologies", RFC 8346, DOI 10.17487/RFC8346, March 2018, <https://www.rfc-editor.org/info/rfc8346>. [RFC8348] Bierman, A., Bjorklund, M., Dong, J., and D. Romascanu, "A YANG Data Model for Hardware Management", RFC 8348, DOI 10.17487/RFC8348, March 2018, <https://www.rfc-editor.org/info/rfc8348>. [RFC8349] Lhotka, L., Lindem, A., and Y. Qu, "A YANG Data Model for Routing Management (NMDA Version)", RFC 8349, DOI 10.17487/RFC8349, March 2018, <https://www.rfc-editor.org/info/rfc8349>. [RFC8466] Wen, B., Fioccola, G., Ed., Xie, C., and L. Jalil, "A YANG Data Model for Layer 2 Virtual Private Network (L2VPN) Service Delivery", RFC 8466, DOI 10.17487/RFC8466, October 2018, <https://www.rfc-editor.org/info/rfc8466>. [RFC8512] Boucadair, M., Ed., Sivakumar, S., Jacquenet, C., Vinapamula, S., and Q. Wu, "A YANG Module for Network Address Translation (NAT) and Network Prefix Translation (NPT)", RFC 8512, DOI 10.17487/RFC8512, January 2019, <https://www.rfc-editor.org/info/rfc8512>. [RFC8513] Boucadair, M., Jacquenet, C., and S. Sivakumar, "A YANG Data Model for Dual-Stack Lite (DS-Lite)", RFC 8513, DOI 10.17487/RFC8513, January 2019, <https://www.rfc-editor.org/info/rfc8513>. [RFC8519] Jethanandani, M., Agarwal, S., Huang, L., and D. Blair, "YANG Data Model for Network Access Control Lists (ACLs)", RFC 8519, DOI 10.17487/RFC8519, March 2019, <https://www.rfc-editor.org/info/rfc8519>. [RFC8528] Bjorklund, M. and L. Lhotka, "YANG Schema Mount", RFC 8528, DOI 10.17487/RFC8528, March 2019, <https://www.rfc-editor.org/info/rfc8528>. Wu, et al. Expires March 26, 2021 [Page 30] Internet-Draft Service and Network Management Automation September 2020 [RFC8529] Berger, L., Hopps, C., Lindem, A., Bogdanovic, D., and X. Liu, "YANG Data Model for Network Instances", RFC 8529, DOI 10.17487/RFC8529, March 2019, <https://www.rfc-editor.org/info/rfc8529>. [RFC8530] Berger, L., Hopps, C., Lindem, A., Bogdanovic, D., and X. Liu, "YANG Model for Logical Network Elements", RFC 8530, DOI 10.17487/RFC8530, March 2019, <https://www.rfc-editor.org/info/rfc8530>. [RFC8531] Kumar, D., Wu, Q., and Z. Wang, "Generic YANG Data Model for Connection-Oriented Operations, Administration, and Maintenance (OAM) Protocols", RFC 8531, DOI 10.17487/RFC8531, April 2019, <https://www.rfc-editor.org/info/rfc8531>. [RFC8532] Kumar, D., Wang, Z., Wu, Q., Ed., Rahman, R., and S. Raghavan, "Generic YANG Data Model for the Management of Operations, Administration, and Maintenance (OAM) Protocols That Use Connectionless Communications", RFC 8532, DOI 10.17487/RFC8532, April 2019, <https://www.rfc-editor.org/info/rfc8532>. [RFC8533] Kumar, D., Wang, M., Wu, Q., Ed., Rahman, R., and S. Raghavan, "A YANG Data Model for Retrieval Methods for the Management of Operations, Administration, and Maintenance (OAM) Protocols That Use Connectionless Communications", RFC 8533, DOI 10.17487/RFC8533, April 2019, <https://www.rfc-editor.org/info/rfc8533>. [RFC8632] Vallin, S. and M. Bjorklund, "A YANG Data Model for Alarm Management", RFC 8632, DOI 10.17487/RFC8632, September 2019, <https://www.rfc-editor.org/info/rfc8632>. [RFC8652] Liu, X., Guo, F., Sivakumar, M., McAllister, P., and A. Peter, "A YANG Data Model for the Internet Group Management Protocol (IGMP) and Multicast Listener Discovery (MLD)", RFC 8652, DOI 10.17487/RFC8652, November 2019, <https://www.rfc-editor.org/info/rfc8652>. [RFC8675] Boucadair, M., Farrer, I., and R. Asati, "A YANG Data Model for Tunnel Interface Types", RFC 8675, DOI 10.17487/RFC8675, November 2019, <https://www.rfc-editor.org/info/rfc8675>. Wu, et al. Expires March 26, 2021 [Page 31] Internet-Draft Service and Network Management Automation September 2020 [RFC8676] Farrer, I., Ed. and M. Boucadair, Ed., "YANG Modules for IPv4-in-IPv6 Address plus Port (A+P) Softwires", RFC 8676, DOI 10.17487/RFC8676, November 2019, <https://www.rfc-editor.org/info/rfc8676>. [RFC8783] Boucadair, M., Ed. and T. Reddy.K, Ed., "Distributed Denial-of-Service Open Threat Signaling (DOTS) Data Channel Specification", RFC 8783, DOI 10.17487/RFC8783, May 2020, <https://www.rfc-editor.org/info/rfc8783>. [RFC8795] Liu, X., Bryskin, I., Beeram, V., Saad, T., Shah, H., and O. Gonzalez de Dios, "YANG Data Model for Traffic Engineering (TE) Topologies", RFC 8795, DOI 10.17487/RFC8795, August 2020, <https://www.rfc-editor.org/info/rfc8795>. Appendix A. Layered YANG Modules Examples Overview This appendix lists a set of YANG data models that can be used for the delivery of connectivity services. These models can be classified as Service, Network, or Device Models. It is not the intent of this appendix to provide an inventory of tools and mechanisms used in specific network and service management domains; such inventory can be found in documents such as [RFC7276]. The reader may refer to the YANG Catalog (<https://www.yangcatalog.org>) or the public Github YANG repository (<https://github.com/YangModels/yang>) to query existing YANG models. The YANG Catalog includes some metadata to indicate the module type ('module-classification') [I-D.clacla-netmod-model-catalog]. Note that the mechanism defined in [I-D.ietf-netmod-module-tags] allows to associate tags with YANG modules in order to help classifying the modules. A.1. Service Models: Definition and Samples As described in [RFC8309], the service is "some form of connectivity between customer sites and the Internet and/or between customer sites across the network operator's network and across the Internet". More concretely, an IP connectivity service can be defined as the IP transfer capability characterized by a (Source Nets, Destination Nets, Guarantees, Scope) tuple where "Source Nets" is a group of unicast IP addresses, "Destination Nets" is a group of IP unicast and/or multicast addresses, and "Guarantees" reflects the guarantees (expressed in terms of QoS, performance, and availability, for example) to properly forward traffic to the said "Destination" [RFC7297]. Wu, et al. Expires March 26, 2021 [Page 32] Internet-Draft Service and Network Management Automation September 2020 For example: o The L3SM model [RFC8299] defines the L3VPN service ordered by a customer from a network operator. o The L2SM model [RFC8466] defines the L2VPN service ordered by a customer from a network operator. o The Virtual Network (VN) model [I-D.ietf-teas-actn-vn-yang] provides a YANG data model applicable to any mode of VN operation. L2SM and L3SM are customer service models as per [RFC8309]. A.2. 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. [RFC8528] 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. A.3. Network Models: Samples L2NM [I-D.ietf-opsawg-l2nm] and L3NM [I-D.ietf-opsawg-l3sm-l3nm] are examples of YANG Network Models. Figure 9 depicts a set of additional Network Models such as topology and tunnel models: Wu, et al. Expires March 26, 2021 [Page 33] Internet-Draft Service and Network Management Automation September 2020 +-------------------------------+-------------------------------+ | Topology YANG modules | Tunnel YANG modules | +-------------------------------+-------------------------------+ | +------------------+ | | | |Network Topologies| | +------+ +-----------+ | | | Model | | |Other | | TE Tunnel | | | +--------+---------+ | |Tunnel| +----+------+ | | | +---------+ | +------+ | | | +---+Service | | +----------+---------+ | | | |Topology | | | | | | | | +---------+ | | | | | | | +---------+ |+----+---+ +----+---+ +---+---+| | +---+Layer 3 | ||MPLS-TE | |RSVP-TE | | SR-TE || | | |Topology | || Tunnel | | Tunnel | |Tunnel || | | +---------+ |+--------+ +--------+ +-------+| | | +---------+ | | | +---+TE | | | | | |Topology | | | | | +---------+ | | | | +---------+ | | | +---+Layer 3 | | | | |Topology | | | | +---------+ | | +-------------------------------+-------------------------------+ Figure 9: Sample Resource Facing Network Models Examples of topology YANG modules are listed below: o Network Topologies Model: [RFC8345] defines a base model for network topology and inventories. Network topology data include link resource, node resource, and terminate-point resources. o TE Topology Model: [RFC8795] defines a YANG data model for representing and manipulating TE topologies. This module is extended from network topology model defined in [RFC8345] with TE topologies related content. This model contains technology-agnostic TE Topology building blocks that can be augmented and used by other technology-specific TE topology models. o Layer 3 Topology Model: [RFC8346] defines a YANG data model for representing and manipulating Layer 3 topologies. This model is extended from the network topology model defined in [RFC8345] with Layer 3 topologies specifics. Wu, et al. Expires March 26, 2021 [Page 34] Internet-Draft Service and Network Management Automation September 2020 o Layer 2 Topology Model: [I-D.ietf-i2rs-yang-l2-network-topology] defines a YANG data model for representing and manipulating Layer 2 topologies. This model is extended from the network topology model defined in [RFC8345] with Layer 2 topology specifics. Examples of tunnel YANG modules are provided below: o Tunnel identities: [RFC8675] defines a collection of YANG identities used as interface types for tunnel interfaces. o TE Tunnel Model: [I-D.ietf-teas-yang-te] defines a YANG module for the configuration and management of TE interfaces, tunnels, and LSPs. o Segment Routing (SR) Traffic Engineering (TE) Tunnel Model: [I-D.ietf-teas-yang-te] augments the TE generic and MPLS-TE model(s) and defines a YANG module for SR-TE specific data. o MPLS-TE Model: [I-D.ietf-teas-yang-te] augments the TE generic and MPLS-TE model(s) and defines a YANG module for MPLS-TE configurations, state, RPC and notifications. o RSVP-TE MPLS Model: [I-D.ietf-teas-yang-rsvp-te] augments the RSVP-TE generic module with parameters to configure and manage signaling of MPLS RSVP-TE LSPs. Other sample Network Models are listed hereafter: o Path Computation API Model: [I-D.ietf-teas-yang-path-computation] YANG module for a stateless RPC which complements the stateful solution defined in [I-D.ietf-teas-yang-te]. o OAM Models (including Fault Management (FM) and Performance Monitoring): [RFC8532] defines a base YANG module for the management of OAM protocols that use Connectionless Communications. [RFC8533] defines a retrieval method YANG module for connectionless OAM Wu, et al. Expires March 26, 2021 [Page 35] Internet-Draft Service and Network Management Automation September 2020 protocols. [RFC8531] defines a base YANG module for connection oriented OAM protocols. These three models are intended to provide consistent reporting, configuration, and representation for connection-less OAM and Connection oriented OAM separately. Alarm monitoring is a fundamental part of monitoring the network. Raw alarms from devices do not always tell the status of the network services or necessarily point to the root cause. [RFC8632] defines a YANG module for alarm management. A.4. Device Models: Samples Network Element models (Figure 10) are used to describe how a service can be implemented by activating and tweaking a set of functions (enabled in one or multiple devices, or hosted in cloud infrastructures) that are involved in the service delivery. Figure 10 uses IETF-defined data models as an example. Wu, et al. Expires March 26, 2021 [Page 36] Internet-Draft Service and Network Management Automation September 2020 +------------------------+ +-+ Device Model | | +------------------------+ | +------------------------+ +---------------+ | | Logical Network | | | +-+ Element Model | | Architecture | | +------------------------+ | | | +------------------------+ +-------+-------+ +-+ Network Instance Model | | | +------------------------+ | | +------------------------+ | +-+ Routing Type Model | | +------------------------+ +-------+----------+----+------+------------+-----------+------+ | | | | | | | +-+-+ +---+---+ +----+----+ +--+--+ +----+----+ +--+--+ | |ACL| |Routing| |Transport| | OAM | |Multicast| | PM | Others +---+ +-+-----+ +----+----+ +--+--+ +-----+---+ +--+--+ | +-------+ | +------+ | +--------+ | +-----+ | +-----+ +-+Core | +-+ MPLS | +-+ BFD | +-+IGMP | +-+TWAMP| | |Routing| | | Base | | +--------+ | |/MLD | | +-----+ | +-------+ | +------+ | +--------+ | +-----+ | +-----+ | +-------+ | +------+ +-+LSP Ping| | +-----+ +-+OWAMP| +-+ BGP | +-+ MPLS | | +--------+ +-+ PIM | | +-----+ | +-------+ | | LDP | | +--------+ | +-----+ | +-----+ | +-------+ | +------+ +-+MPLS-TP | | +-----+ +-+LMAP | +-+ ISIS | | +------+ +--------+ +-+ MVPN| +-----+ | +-------+ +-+ MPLS | +-----+ | +-------+ |Static| +-+ OSPF | +------+ | +-------+ | +-------+ +-+ RIP | | +-------+ | +-------+ +-+ VRRP | | +-------+ | +-------+ +-+SR/SRv6| | +-------+ | +-------+ +-+ISIS-SR| | +-------+ | +-------+ +-+OSPF-SR| +-------+ Figure 10: Network Element Modules Overview Wu, et al. Expires March 26, 2021 [Page 37] Internet-Draft Service and Network Management Automation September 2020 A.4.1. Model Composition o Logical Network Element Model [RFC8530] defines a logical network element module which can be used to manage the logical resource partitioning that may be present on a network device. Examples of common industry terms for logical resource partitioning are Logical Systems or Logical Routers. o Network Instance Model [RFC8529] defines a network instance module. This module can be used to manage the virtual resource partitioning that may be present on a network device. Examples of common industry terms for virtual resource partitioning are VRF instances and Virtual Switch Instances (VSIs). A.4.2. Device Management The following list enumerates some YANG modules that can be used for device management: o [RFC8348]: defines a YANG module for the management of hardware. o [RFC7317]: defines the "ietf-system" YANG module that provides many features such as the configuration and the monitoring of system or system control operations (e.g., shutdown, restart, setting time) identification. o [RFC8341]: defines a network configuration access control YANG module. A.4.3. Interface Management The following provides some YANG modules that can be used for interface management: o [RFC7224]: defines a YANG module for interface type definitions. o [RFC8343]: defines a YANG module for the management of network interfaces. A.4.4. Some Device Model Examples The following provides an overview of some Device Models that can be used within a network. This list is not comprehensive. Wu, et al. Expires March 26, 2021 [Page 38] Internet-Draft Service and Network Management Automation September 2020 L2VPN: [I-D.ietf-bess-l2vpn-yang] defines a YANG module for MPLS based Layer 2 VPN services (L2VPN) [RFC4664] and includes switching between the local attachment circuits. The L2VPN model covers point-to-point VPWS and Multipoint VPLS services. These services use signaling of Pseudowires across MPLS networks using LDP [RFC8077][RFC4762] or BGP [RFC4761]. EVPN: [I-D.ietf-bess-evpn-yang] defines a YANG module for Ethernet VPN services. The model is agnostic of the underlay. It applies to MPLS as well as to VxLAN encapsulation. The module is also agnostic to the services, including E-LAN, E-LINE, and E-TREE services. L3VPN: [I-D.ietf-bess-l3vpn-yang] defines a YANG module that can be used to configure and manage BGP L3VPNs [RFC4364]. It contains VRF specific parameters as well as BGP specific parameters applicable for L3VPNs. Core Routing: [RFC8349] defines the core routing YANG data model, which is intended as a basis for future data model development covering more-sophisticated routing systems. It is expected that other Routing technology YANG modules (e.g., VRRP, RIP, ISIS, OSPF models) will augment the Core Routing base YANG module. MPLS: [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 modules (e.g., MPLS LSP Static, LDP, or RSVP-TE models) will augment the MPLS base YANG module. BGP: [I-D.ietf-idr-bgp-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. Routing Policy: [I-D.ietf-rtgwg-policy-model] defines a YANG module for configuring and managing routing policies based on operational practice. The module provides a generic policy framework which can be augmented with protocol- specific policy configuration. SR/SRv6: [I-D.ietf-spring-sr-yang] a YANG module for segment routing configuration and operation. Wu, et al. Expires March 26, 2021 [Page 39] Internet-Draft Service and Network Management Automation September 2020 BFD: Bidirectional Forwarding Detection (BFD) [RFC5880] is a network protocol which is used for liveness detection of arbitrary paths between systems. [I-D.ietf-bfd-yang] defines a YANG module that can be used to configure and manage BFD. Multicast: [I-D.ietf-pim-yang] defines a YANG module that can be used to configure and manage Protocol Independent Multicast (PIM) devices. [RFC8652] defines a YANG module that can be used to configure and manage Internet Group Management Protocol (IGMP) and Multicast Listener Discovery (MLD) devices. [I-D.ietf-pim-igmp-mld-snooping-yang] defines a YANG module that can be used to configure and manage Internet Group Management Protocol (IGMP) and Multicast Listener Discovery (MLD) Snooping devices. [I-D.ietf-bess-mvpn-yang] defines a YANG data model to configure and manage Multicast in MPLS/BGP IP VPNs (MVPNs). PM: [I-D.ietf-ippm-twamp-yang] defines a YANG data model for client and server implementations of the Two-Way Active Measurement Protocol (TWAMP). [I-D.ietf-ippm-stamp-yang] defines the data model for implementations of Session-Sender and Session-Reflector for Simple Two-way Active Measurement Protocol (STAMP) mode using YANG. [RFC8194] defines a YANG data model for Large-Scale Measurement Platforms (LMAPs). ACL: 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. [RFC8519] describes a YANG data model of ACL basic building blocks. QoS: [I-D.ietf-rtgwg-qos-model] describes a YANG module of Differentiated Services for configuration and operations. NAT: For the sake of network automation and the need for programming Network Address Translation (NAT) function in particular, a YANG data model for configuring and managing the NAT is essential. Wu, et al. Expires March 26, 2021 [Page 40] Internet-Draft Service and Network Management Automation September 2020 [RFC8512] defines a YANG module for the NAT function covering a variety of NAT flavors such as Network Address Translation from IPv4 to IPv4 (NAT44), Network Address and Protocol Translation from IPv6 Clients to IPv4 Servers (NAT64), customer-side translator (CLAT), Stateless IP/ ICMP Translation (SIIT), Explicit Address Mappings (EAM) for SIIT, IPv6-to-IPv6 Network Prefix Translation (NPTv6), and Destination NAT. [RFC8513] specifies a DS-Lite YANG module. Stateless Address Sharing: [RFC8676] specifies a YANG module for A+P address sharing, including Lightweight 4over6, Mapping of Address and Port with Encapsulation (MAP-E), and Mapping of Address and Port using Translation (MAP-T) softwire mechanisms. Authors' Addresses Qin Wu (editor) Huawei 101 Software Avenue, Yuhua District Nanjing, Jiangsu 210012 China Email: bill.wu@huawei.com Mohamed Boucadair (editor) Orange Rennes 35000 France Email: mohamed.boucadair@orange.com Diego R. Lopez Telefonica I+D Spain Email: diego.r.lopez@telefonica.com Wu, et al. Expires March 26, 2021 [Page 41] Internet-Draft Service and Network Management Automation September 2020 Chongfeng Xie China Telecom Beijing China Email: xiechf@chinatelecom.cn Liang Geng China Mobile Email: gengliang@chinamobile.com Wu, et al. Expires March 26, 2021 [Page 42]