]> Telefonica

oscar.gonzalezdedios@telefonica.com

Nokia

samier.barguil_giraldo@nokia.com

Nokia

victor.lopez@nokia.com

Operations and Management opsawg This document defines a YANG data model for representing an abstracted view of a network topology that contains Open Shortest Path First (OSPF) information. This document augments the 'ietf-network' data model by adding OSPF concepts and explains how the data model can be used to represent the OSPF topology. The YANG data model defined in this document conforms to the Network Management Datastore Architecture (NMDA).

Introduction Topology collection is a critical use case for network operators because the network topology is an abstract representation of the physical nodes, links, and network interconnections. Network planning processes require that network resources are placed to meet traffic demand requirements not just in terms of bandwidth or delay, but also for failure scenarios. Network operators perform the network planning process as an offline process, which obtains information not directly from the network, but from inventory or template information. The main reason for this process was the lack of dynamic and programmatic interfaces that can allow planning tools to obtain such information. Thanks to the definition of the ietf-network model in this situation has changed, because network operators can use an API with dynamic topological information. On top of the work in , and extends the generic network and network topology data models with topology attributes that are specific to Layer 3 and Layer 2. However, there is not any model that exposes Open Shortest Path First (OSPF) information. This information is required in the IP/MPLS planning process to properly assess the required network resources to meet the traffic demands in normal and failure scenarios. The main objective of this model is to represent most relevant OSPF topology attributes. This document defines a YANG data model for representing, managing, and controlling the OSPF topology. The data model augments ietf-network module by adding the OSPF information. This document explains the scope and purpose of the OSPF topology model and how the topology and service models fit together. The YANG data model defined in this document conforms to the Network Management Datastore Architecture .

Terminology and Notations This document assumes that the reader is familiar with OSPF and the contents of . The document uses terms from those documents. The terminology for describing YANG data models is found in , and .

Requirements Language 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 , when, and only when, they appear in all capitals, as shown here.

Tree Diagram Authors include a simplified graphical representation of the data model is used in of this document. The meaning of the symbols in these diagrams is defined in .

Prefix in Data Node Names In this document, names of data nodes and other data model objects are prefixed using the standard prefix associated with the corresponding YANG imported modules, as shown in the following table. Prefixes and corresponding YANG modules

Prefix	Yang Module	Reference
ospfnt	ietf-l3-ospf-topology	RFCXXX
yang	ietf-yang-types

RFC Editor Note: Please replace XXXX with the RFC number assigned to this document. Please remove this note.

YANG Data Model for OSPF Topology The abstract (base) network data model is defined in the "ietf-network" module of . The OSPF-topology builds on the network data model defined in the "ietf-network" module , augmenting the nodes with OSPF information, which anchor the links and are contained in nodes. There is a set of parameters and augmentations that are included at the node level. Each parameter and description are detailed following:

• Network-types: Its presence identifies the OSPF topology type. Thus, the network type MUST be ospf-topology.
• OSPF timer attributes: Identifies the node timer attributes configured in the network element. They are wait timer, rapid delay, slow delay, and the timer type (linear or exponential back-off).
• OSPF status: contains the neighbours' information.

A second set of parameters, along with augmentations, is included at the link and termination point level. Each parameter is listed as follows:

• Interface-type
• Area ID
• Metric
• Passive mode

OSPF Topology Tree Diagram below shows the tree diagram of the YANG data model defined in module ietf-l3-ospf-topology.yang ().

OSPF Topology tree diagram

YANG Model for OSPF topology Following the YANG model is presented.

OSPF Topology YANG module WG List: Editor: Oscar Gonzalez de Dios Editor: Samier Barguil Editor: Victor Lopez "; description "This module defines a model for Layer 3 OSPF topologies. Copyright (c) 2022 IETF Trust and the persons identified as authors of the code. All rights reserved. Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to the license terms contained in, the Revised BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info). This version of this YANG module is part of RFC XXXX (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself for full legal notices."; revision 2022-03-07 { description "Initial version"; reference "RFC XXXX: A YANG Data Model for Open Shortest Path First (OSPF) Topology"; } typedef area-id-type { type yang:dotted-quad; description "An identifier for the OSPFv2 area."; reference "RFC 2328: OSPF Version 2"; } identity inf-type { description "Identity for the OSPF interface type."; reference "RFC 2328: OSPF Version 2"; } identity nbma { base inf-type; description "Identity for the NBMA interface."; reference "RFC 2328: OSPF Version 2"; } identity p2mp { base inf-type; description "Identity for the p2mp interface."; reference "RFC 2328: OSPF Version 2"; } identity p2mp-over-lan { base inf-type; description "Identity for the p2mp-over-lan interface."; reference "RFC 2328: OSPF Version 2"; } identity p2p { base inf-type; description "Identity for the p2p interface."; reference "RFC 2328: OSPF Version 2"; } grouping ospfv2-topology-type { description "Identifies the topology type to be OSPF v2."; container ospfv2-topology { presence "indicates OSPF v2 topology"; description "The presence of the container node indicates OSPF v2 topology"; } } grouping ospfv2-node-attributes { description "OSPF v2 node scope attributes"; container ospf-timer-attributes { description "Contains OSPFv2 node timer attributes"; leaf wait-timer { type uint32; units msec; description "The amount of time to wait without detecting SPF trigger events before going back to the rapid delay."; reference "RFC 8541: SPF Impact on IGP Micro-loops"; } leaf rapid-delay { type uint32; units msec; description "The amount of time to wait before running SPF after the initial SPF trigger event."; reference "RFC 8541: SPF Impact on IGP Micro-loops"; } leaf slow-delay { type uint32; units msec; description "The amount of time to wait before running an SPF."; reference "RFC 8541: SPF Impact on IGP Micro-loops"; } leaf timer-type { type enumeration { enum LINEAR_BACKOFF { description "The link state routing protocol uses linear back-off."; } enum EXPONENTIAL_BACKOFF { description "The link state routing protocol uses exponential back-off."; } } description "The timer mode that is utilised by the SPF algorithm."; reference "RFC 8541: SPF Impact on IGP Micro-loops"; } } } grouping ospfv2-termination-point-attributes { description "OSPF termination point scope attributes"; container ospfv2-termination-point-attributes { description "Indicates the termination point from the which the OSPF is configured. A termination point can be a physical port, an interface, etc."; leaf interface-type { type identityref { base inf-type ; } description "OSPF interface type."; reference "RFC 2328: OSPF Version 2"; } leaf area-id { type area-id-type; description "An identifier for the OSPFv2 area."; reference "RFC 2328: OSPF Version 2"; } leaf metric { type uint64; description "OSFP Protocol metric"; reference "RFC 2328: OSPF Version 2"; } leaf is-passive{ type boolean; description "Interface passive mode"; reference "RFC 2328: OSPF Version 2"; } } } augment "/nw:networks/nw:network/nw:network-types" { description "Introduces new network type for L3 Unicast topology"; uses ospfv2-topology-type; } augment "/nw:networks/nw:network/nw:node/" +"l3t:l3-node-attributes" { when "/nw:networks/nw:network/nw:network-types/" +"ospfnt:ospfv2-topology" { description "Augmentation parameters apply only for networks with OSPF topology"; } description "OSPF node-level attributes "; uses ospfv2-node-attributes; } augment "/nw:networks/nw:network/" + "nt:link/l3t:l3-link-attributes" { when "/nw:networks/nw:network/nw:network-types/" +"ospfnt:ospfv2-topology" { description "Augmentation parameters apply only for networks with OSFP topology"; } description "Augments topology link configuration"; uses ospfv2-termination-point-attributes; } augment "/nw:networks/nw:network/nw:node/" +"nt:termination-point/l3t:l3-termination-point-attributes" { when "/nw:networks/nw:network/nw:network-types/" +"ospfnt:ospfv2-topology" { description "Augmentation parameters apply only for networks with OSFP topology"; } description "Augments topology termination point configuration"; uses ospfv2-termination-point-attributes; } } ]]>

Security Considerations The YANG module specified in this document defines a schema for data that is designed to be accessed via network management protocols such as NETCONF {!RFC6241}} 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 this YANG module that are writable/creatable/deletable (i.e., config true, which is the default). These data nodes may be considered sensitive or vulnerable in some network environments. Write operations (e.g., edit-config) to these data nodes without proper protection can have a negative effect on network operations.

IANA Considerations This document registers the following namespace URIs in the IETF XML registry : This document registers the following YANG module in the YANG Module Names registry :

Implementation Status This section will be used to track the status of the implementations of the model. It is aimed at being removed if the document becomes RFC.

Normative References This document defines an abstract (generic, or base) YANG data model for network/service topologies and inventories. The data model serves as a base model that is augmented with technology-specific details in other, more specific topology and inventory data models. This document defines a YANG data model for Layer 3 network topologies. This document defines a YANG data model for Layer 2 network topologies. In particular, this data model augments the generic network and network topology data models with topology attributes that are specific to Layer 2. 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. YANG is a data modeling language used to model configuration data, state data, Remote Procedure Calls, and notifications for network management protocols. This document describes the syntax and semantics of version 1.1 of the YANG language. YANG version 1.1 is a maintenance release of the YANG language, addressing ambiguities and defects in the original specification. There are a small number of backward incompatibilities from YANG version 1. This document also specifies the YANG mappings to the Network Configuration Protocol (NETCONF). This document defines a YANG data model for representing, retrieving, and manipulating Traffic Engineering (TE) Topologies. The model serves as a base model that other technology-specific TE topology models can augment. 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. 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. 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. This document introduces a collection of common data types to be used with the YANG data modeling language. This document obsoletes RFC 6021. 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). 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] 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 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. 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 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]

Acknowledgments This work is partially supported by the European Commission under Horizon 2020 Secured autonomic traffic management for a Tera of SDN flows (Teraflow) project (grant agreement number 101015857).