Network Working Group A. Clemm Internet-Draft Huawei USA Intended status: Standards Track J. Medved Expires: June 19, 2018 Cisco R. Varga Pantheon Technologies SRO X. Liu Jabil H. Ananthakrishnan Packet Design N. Bahadur Bracket Computing December 16, 2017 A YANG Data Model for Layer 3 Topologies draft-ietf-i2rs-yang-l3-topology-16.txt Abstract This document defines a YANG data model for layer 3 network topologies. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on June 19, 2018. Copyright Notice Copyright (c) 2017 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of Clemm, et al. Expires June 19, 2018 [Page 1] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Key Words . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Definitions and Acronyms . . . . . . . . . . . . . . . . . . 3 4. Model Structure . . . . . . . . . . . . . . . . . . . . . . . 4 5. Layer 3 Unicast Topology Model Overview . . . . . . . . . . . 5 6. Layer 3 Unicast Topology YANG Module . . . . . . . . . . . . 7 7. Interactions with Other YANG Modules . . . . . . . . . . . . 15 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 9. Security Considerations . . . . . . . . . . . . . . . . . . . 16 10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 17 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 17 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 17 12.1. Normative References . . . . . . . . . . . . . . . . . . 17 12.2. Informative References . . . . . . . . . . . . . . . . . 19 Appendix A. Companion YANG model for non-NMDA compliant implementations . . . . . . . . . . . . . . . . . . 20 Appendix B. Extending the Model . . . . . . . . . . . . . . . . 24 B.1. Example OSPF Topology . . . . . . . . . . . . . . . . . . 24 B.1.1. Model Overview . . . . . . . . . . . . . . . . . . . 24 B.1.2. OSPF Topology YANG Module . . . . . . . . . . . . . . 26 Appendix C. An Example . . . . . . . . . . . . . . . . . . . . . 29 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 34 1. Introduction This document introduces a YANG [RFC7950] [RFC6991] data model for Layer 3 network topologies, specifically Layer 3 Unicast. The model allows an application to have a holistic view of the topology of a Layer 3 network, all contained in a single conceptual YANG datastore. The data model builds on top of, and augments, the data model for network topologies defined in [I-D.draft-ietf-i2rs-yang-network-topo]. This document also shows how the model can be further refined to cover different Layer 3 Unicast topology types. For this purpose, an example model is introduced that covers OSPF [RFC2328]. This example is intended purely for illustrative purpose; we expect that a complete OSPF model will be more comprehensive and refined than the example shown here. Clemm, et al. Expires June 19, 2018 [Page 2] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 There are multiple applications for a topology data model. A number of use cases have been defined in section 6 of [I-D.draft-ietf-i2rs-usecase-reqs-summary]. For example, nodes within the network can use the data model to capture their understanding of the overall network topology and expose it to a network controller. A network controller can then use the instantiated topology data to compare and reconcile its own view of the network topology with that of the network elements that it controls. Alternatively, nodes within the network could propagate this understanding to compare and reconcile this understanding either amongst themselves or with help of a controller. Beyond the network element itself, a network controller might even use the data model to represent its view of the topology that it controls and expose it to applications north of itself. The data model for Layer 3 Unicast topologies defined in this document is specified in a YANG module "ietf-l3-unicast-topology". To do so, it augments the general network topology model defined in [I-D.draft-ietf-i2rs-yang-network-topo] with information specific to Layer 3 Unicast. This way, the general topology model is extended to be able to meet the needs of Layer 3 Unicast topologies. Information that is kept in the Traffic Engineering Database (TED) will be specified in a separate model [I-D.draft-ietf-teas-yang-te-topo] and outside the scope of this specification. 2. Key Words The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. 3. Definitions and Acronyms As this document defines a YANG data model, in this document many terms are used that have been defined in conjunction with YANG [RFC7950] and NETCONF [RFC6241]. Some terms, such as datastore and data tree, are repeated here for clarity and to put them in context. Datastore: A conceptual place to store and access information. A datastore might be implemented, for example, using files, a database, flash memory locations, or combinations thereof. A datastore maps to an instantiated YANG data tree. (Definition adopted from [I-D.draft-ietf-netmod-revised-datastores]) Clemm, et al. Expires June 19, 2018 [Page 3] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 Data subtree: An instantiated data node and the data nodes that are hierarchically contained within it. IGP: Interior Gateway Protocol IS-IS: Intermediate System to Intermediate System protocol LSP: Label Switched Path NETCONF: Network Configuration Protocol NMDA: Network Management Datastore Architecture OSPF: Open Shortest Path First, a link state routing protocol URI: Uniform Resource Identifier SRLG: Shared Risk Link Group TED: Traffic Engineering Database YANG: YANG is a data modeling language used to model configuration data, state data, Remote Procedure Calls, and notifications for network management protocols [RFC7950] 4. Model Structure The Layer 3 Unicast topology model is defined by YANG module "l3- unicast-topology". The relationship of this module with other YANG modules is roughly depicted in the figure below. Clemm, et al. Expires June 19, 2018 [Page 4] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 +-----------------------------+ | +-----------------------+ | | | ietf-network | | | +----------^------------+ | | | | | +-----------------------+ | | | ietf-network-topology | | | +----------+------------+ | +-------------^---------------+ | | +------------^-------------+ | ietf-l3-unicast-topology | +------------^-------------+ | | +-----------^-----------+ | example-ospf-topology | +-----------------------+ Figure 1: Overall model structure YANG modules "ietf-network" and "ietf-network-topology" collectively define the basic network topology model [I-D.draft-ietf-i2rs-yang-network-topo]. YANG module "ietf-l3- unicast-topology" augments those models with additional definitions needed to represent Layer 3 Unicast topologies. This module in turn can be augmented by YANG modules with additional definitions for specific types of Layer 3 Unicast topologies, such as OSPF and for IS-IS topologies. The YANG modules ietf-network and ietf-network-topology are designed to be used in conjunction with implementations that support the Network Management Datastore Architecture (NMDA) defined in [I-D.draft-ietf-netmod-revised-datastores]. Accordingly, the same is true for the YANG modules that augment it. In order to allow implementations to use the model even in cases when NMDA is not supported, companion YANG modules (that SHOULD NOT be supported by implementations that support NMDA) are defined in an Appendix, see Appendix A. 5. Layer 3 Unicast Topology Model Overview The Layer 3 Unicast topology model is defined by YANG module "ietf- l3-unicast-topology". Its structure is depicted in the following diagram. The notation syntax follows [I-D.draft-ietf-netmod-yang-tree-diagrams]. For purposes of brevity, notifications are not depicted. Clemm, et al. Expires June 19, 2018 [Page 5] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 module: ietf-l3-unicast-topology augment /nw:networks/nw:network/nw:network-types: +--rw l3-unicast-topology! augment /nw:networks/nw:network: +--rw l3-topology-attributes +--rw name? string +--rw flag* l3-flag-type augment /nw:networks/nw:network/nw:node: +--rw l3-node-attributes +--rw name? inet:domain-name +--rw flag* node-flag-type +--rw router-id* rt-types:router-id +--rw prefix* [prefix] +--rw prefix inet:ip-prefix +--rw metric? uint32 +--rw flag* prefix-flag-type augment /nw:networks/nw:network/nt:link: +--rw l3-link-attributes +--rw name? string +--rw flag* link-flag-type +--rw metric1? uint64 +--rw metric2? uint64 augment /nw:networks/nw:network/nw:node/nt:termination-point: +--rw l3-termination-point-attributes +--rw (termination-point-type)? +--:(ip) | +--rw ip-address* inet:ip-address +--:(unnumbered) | +--rw unnumbered-id? uint32 +--:(interface-name) +--rw interface-name? string The module augments the original ietf-network and ietf-network- topology modules as follows: o A new network topology type is introduced, l3-unicast-topology. The corresponding container augments the network-types of the ietf-network module. o Additional topology attributes are introduced, defined in a grouping, which augments the "network" list of the network module. The attributes include a name for the topology, as well as a set of flags (represented through a leaf-list). Each type of flag is represented by a separate identity. This allows to introduce additional flags in augmenting modules using additional identities without needing to revise this module. Clemm, et al. Expires June 19, 2018 [Page 6] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 o Additional data objects for nodes are introduced by augmenting the "node" list of the network module. New objects include again a set of flags, as well as a list of prefixes. Each prefix in turn includes an ip prefix, a metric, and a prefix-specific set of flags. o Links (in the ietf-network-topology module) are augmented with a set of parameters as well, allowing to associate a link with a link name, another set of flags, and a link metric. o Termination points (in the ietf-network-topology module as well) are augmented with a choice of IP address, identifier, or name. In addition, the module defines a set of notifications to alert clients of any events concerning links, nodes, prefixes, and termination points. Each notification includes an indication of the type of event, the topology from which it originated, and the affected node, or link, or prefix, or termination point. In addition, as a convenience to applications, additional data of the affected node, or link, or termination point (respectively) is included. While this makes notifications larger in volume than they would need to be, it avoids the need for subsequent retrieval of context information, which also might have changed in the meantime. 6. Layer 3 Unicast Topology YANG Module file "ietf-l3-unicast-topology@2017-12-16.yang" module ietf-l3-unicast-topology { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-l3-unicast-topology"; prefix "l3t"; import ietf-network { prefix "nw"; } import ietf-network-topology { prefix "nt"; } import ietf-inet-types { prefix "inet"; } import ietf-routing-types { prefix "rt-types"; } organization "IETF I2RS (Interface to the Routing System) Working Group"; contact "WG Web: Clemm, et al. Expires June 19, 2018 [Page 7] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 WG List: Editor: Alexander Clemm Editor: Jan Medved Editor: Robert Varga Editor: Xufeng Liu Editor: Nitin Bahadur Editor: Hariharan Ananthakrishnan "; description "This module defines a model for Layer 3 Unicast topologies. Copyright (c) 2017 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 Simplified BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info). This version of this YANG module is part of draft-ietf-i2rs-yang-l3-topology-16; see the RFC itself for full legal notices. NOTE TO RFC EDITOR: Please replace above reference to draft-ietf-i2rs-yang-l3-topology-16 with RFC number when published (i.e. RFC xxxx)."; revision "2017-12-16" { description "Initial revision. NOTE TO RFC EDITOR: Please replace the following reference to draft-ietf-i2rs-yang-l3-topology-16 with RFC number when published (i.e. RFC xxxx)."; reference "draft-ietf-i2rs-yang-l3-topology-16"; } identity flag-identity { description "Base type for flags"; } typedef l3-event-type { type enumeration { enum "add" { description Clemm, et al. Expires June 19, 2018 [Page 8] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 "An Layer 3 node or link or prefix or termination-point has been added"; } enum "remove" { description "An Layer 3 node or link or prefix or termination-point has been removed"; } enum "update" { description "An Layer 3 node or link or prefix or termination-point has been updated"; } } description "Layer 3 Event type for notifications"; } typedef prefix-flag-type { type identityref { base "flag-identity"; } description "Prefix flag attributes"; } typedef node-flag-type { type identityref { base "flag-identity"; } description "Node flag attributes"; } typedef link-flag-type { type identityref { base "flag-identity"; } description "Link flag attributes"; } typedef l3-flag-type { type identityref { base "flag-identity"; } description "L3 flag attributes"; } grouping l3-prefix-attributes { description "L3 prefix attributes"; Clemm, et al. Expires June 19, 2018 [Page 9] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 leaf prefix { type inet:ip-prefix; description "IP prefix value"; } leaf metric { type uint32; description "Prefix metric"; } leaf-list flag { type prefix-flag-type; description "Prefix flags"; } } grouping l3-unicast-topology-type { description "Identify the topology type to be L3 unicast."; container l3-unicast-topology { presence "indicates L3 Unicast Topology"; description "The presence of the container node indicates L3 Unicast Topology"; } } grouping l3-topology-attributes { description "Topology scope attributes"; container l3-topology-attributes { description "Containing topology attributes"; leaf name { type string; description "Name of the topology"; } leaf-list flag { type l3-flag-type; description "Topology flags"; } } } grouping l3-node-attributes { description "L3 node scope attributes"; container l3-node-attributes { description "Containing node attributes"; leaf name { type inet:domain-name; Clemm, et al. Expires June 19, 2018 [Page 10] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 description "Node name"; } leaf-list flag { type node-flag-type; description "Node flags"; } leaf-list router-id { type rt-types:router-id; description "Router-id for the node"; } list prefix { key "prefix"; description "A list of prefixes along with their attributes"; uses l3-prefix-attributes; } } } grouping l3-link-attributes { description "L3 link scope attributes"; container l3-link-attributes { description "Containing link attributes"; leaf name { type string; description "Link Name"; } leaf-list flag { type link-flag-type; description "Link flags"; } leaf metric1 { type uint64; description "Link Metric 1"; } leaf metric2 { type uint64; description "Link Metric 2"; } } Clemm, et al. Expires June 19, 2018 [Page 11] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 } grouping l3-termination-point-attributes { description "L3 termination point scope attributes"; container l3-termination-point-attributes { description "Containing termination point attributes"; choice termination-point-type { description "Indicates the termination point type"; case ip { leaf-list ip-address { type inet:ip-address; description "IPv4 or IPv6 address."; } } case unnumbered { leaf unnumbered-id { type uint32; description "Unnumbered interface identifier. The identifier will correspond to the ifIndex value of the interface, i.e. the ifIndex value of the ifEntry that represents the interface in implementations where the Interfaces Group MIB (RFC 2863) is supported."; reference "RFC 2863: The Interfaces Group MIB"; } } case interface-name { leaf interface-name { type string; description "A name of the interface. The name can (but does not have to) correspond to an interface reference of a containing node's interface, i.e. the path name of a corresponding interface data node on the containing node reminiscent of data type if-ref defined in RFC 7223. It should be noted that data type if-ref of RFC 7223 cannot be used directly, as this data type is used to reference an interface in a datastore of a single node in the network, not to uniquely reference interfaces across a network."; } } } } Clemm, et al. Expires June 19, 2018 [Page 12] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 } augment "/nw:networks/nw:network/nw:network-types" { description "Introduce new network type for L3 unicast topology"; uses l3-unicast-topology-type; } augment "/nw:networks/nw:network" { when "nw:network-types/l3t:l3-unicast-topology" { description "Augmentation parameters apply only for networks with L3 unicast topology"; } description "L3 unicast for the network as a whole"; uses l3-topology-attributes; } augment "/nw:networks/nw:network/nw:node" { when "../nw:network-types/l3t:l3-unicast-topology" { description "Augmentation parameters apply only for networks with L3 unicast topology"; } description "L3 unicast node level attributes "; uses l3-node-attributes; } augment "/nw:networks/nw:network/nt:link" { when "../nw:network-types/l3t:l3-unicast-topology" { description "Augmentation parameters apply only for networks with L3 unicast topology"; } description "Augment topology link attributes"; uses l3-link-attributes; } augment "/nw:networks/nw:network/nw:node/" +"nt:termination-point" { when "../../nw:network-types/l3t:l3-unicast-topology" { description "Augmentation parameters apply only for networks with L3 unicast topology"; } description "Augment topology termination point configuration"; uses l3-termination-point-attributes; } notification l3-node-event { description Clemm, et al. Expires June 19, 2018 [Page 13] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 "Notification event for L3 node"; leaf l3-event-type { type l3-event-type; description "Event type"; } uses nw:node-ref; uses l3-unicast-topology-type; uses l3-node-attributes; } notification l3-link-event { description "Notification event for L3 link"; leaf l3-event-type { type l3-event-type; description "Event type"; } uses nt:link-ref; uses l3-unicast-topology-type; uses l3-link-attributes; } notification l3-prefix-event { description "Notification event for L3 prefix"; leaf l3-event-type { type l3-event-type; description "Event type"; } uses nw:node-ref; uses l3-unicast-topology-type; container prefix { description "Containing L3 prefix attributes"; uses l3-prefix-attributes; } } notification termination-point-event { description "Notification event for L3 termination point"; leaf l3-event-type { type l3-event-type; description "Event type"; } uses nt:tp-ref; uses l3-unicast-topology-type; Clemm, et al. Expires June 19, 2018 [Page 14] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 uses l3-termination-point-attributes; } } 7. Interactions with Other YANG Modules As described in section Section 4, the model builds on top of, and augments, the YANG modules defined in [I-D.draft-ietf-i2rs-yang-network-topo]. Specifically, module ietf- l3-unicast-topology augments modules "ietf-network" and "ietf- network-topology". In addition, the model makes use of data types that have been defined in [RFC6991]. The model defines a protocol independent YANG data model with layer 3 topology information. It is separate from and not linked with data models that are used to configure routing protocols or routing information. This includes e.g. model "ietf-routing" [RFC8022] and model "ietf-fb-rib" [I-D.draft-acee-rtgwg-yang-rib-extend]. That said, the model does import a type definition from model "ietf- routing-types" [RFC8294]. The model obeys the requirements for the ephemeral state found in the document [RFC8242]. For ephemeral topology data that is server provided, the process tasked with maintaining topology information will load information from the routing process (such as OSPF) into the data model without relying on a configuration datastore. 8. IANA Considerations This document registers the following namespace URIs in the "IETF XML Registry" [RFC3688]: URI: urn:ietf:params:xml:ns:yang:ietf-l3-unicast-topology Registrant Contact: The IESG. XML: N/A; the requested URI is an XML namespace. URI: urn:ietf:params:xml:ns:yang:ietf-l3-unicast-topology-state Registrant Contact: The IESG. XML: N/A; the requested URI is an XML namespace. This document registers the following YANG modules in the "YANG Module Names" registry [RFC6020]: Name: ietf-l3-unicast-topology Namespace: urn:ietf:params:xml:ns:yang:ietf-l3-unicast-topology Prefix: l3t Clemm, et al. Expires June 19, 2018 [Page 15] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 Reference: draft-ietf-i2rs-yang-l3-topology-16.txt (RFC form) Name: ietf-l3-unicast-topology-state Namespace: urn:ietf:params:xml:ns:yang:ietf-l3-unicast-topology-state Prefix: l3t-s Reference: draft-ietf-i2rs-yang-l3-topology-16.txt (RFC form) 9. Security Considerations The YANG module defined in this document is designed to be accessed via network management protocols such as NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer is the secure transport layer, and the mandatory-to-implement secure transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer is HTTPS, and the mandatory-to-implement secure transport is TLS [RFC5246]. The NETCONF access control model [RFC6536] 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. In general, Layer 3 Unicast topologies are system-controlled and provide ephemeral topology information. In an NMDA-complient server, they are only part of which provides read-only access to clients, they are less vulnerable. That said, the YANG module does in principle allow information to be configurable. There are a number of data nodes defined in this YANG module that are writable/creatable/deletable (i.e., config true, which is the default). These data nodes may be considered sensitive or vulnerable in some network environments. Write operations (e.g., edit-config) to these data nodes without proper protection can have a negative effect on network operations. These are the subtrees and data nodes and their sensitivity/vulnerability in the ietf-network module: l3-topology-attributes: A malicious client could attempt to sabotage the configuration of any of the ctonained attributes, i.e. the name or the flag data nodes. l3-node-attributes: A malicious client could attempt to sabotage the configuration of important node attributes, such as the router-id or node prefix. l3-link-attributes: A malicious client could attempt to sabotage the configuration of important link attributes, such as name, flag, and metrics of the link respectively corresponding data nodes. Clemm, et al. Expires June 19, 2018 [Page 16] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 l3-termination-point-attributes: A malicious client could attempt to sabotage the configuration information of a termination point, such as its ip-address and interface name, respectively the corresponding data nodes. 10. Contributors The model presented in this document was contributed to by more people than can be listed on the author list. Additional contributors include: o Vishnu Pavan Beeram, Juniper o Igor Bryskin, Huawei o Ken Gray, Cisco o Aihua Guo, Huawei o Tom Nadeau, Brocade o Tony Tkacik o Aleksandr Zhdankin, Cisco 11. Acknowledgements We wish to acknowledge the helpful contributions, comments, and suggestions that were received from Alia Atlas, Andy Bierman, Benoit Claise, Joel Halpern, Susan Hares, Ladislav Lhotka, Carl Moberg, Carlos Pignataro, Juergen Schoenwaelder, Michal Vasco, and Kent Watsen. 12. References 12.1. Normative References [I-D.draft-ietf-i2rs-yang-network-topo] Clemm, A., Medved, J., Varga, R., Bahadur, N., Ananthakrishnan, H., and X. Liu, "A YANG Data Model for Network Topologies", I-D draft-ietf-i2rs-yang-network- topo-19, December 2017. [I-D.draft-ietf-netmod-revised-datastores] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K., and R. Wilton, "A Revised Conceptual Model for YANG Datastores", I-D draft-ietf-netmod-revised-datastores-06, October 2017. Clemm, et al. Expires June 19, 2018 [Page 17] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 [RFC1195] Callon, R., "Use of OSI IS-IS for Routing in TCP/IP and Dual Environments", RFC 1195, December 1990. [RFC2119] Bradner, S., "Key words for use in RFCs to indicate requirement levels", RFC 2119, March 1997. [RFC2328] Moy, J., "OSPF Version 2", RFC 2328, April 1998. [RFC2863] McCloghrie, K. and F. Kastenholz, "The Interfaces Group MIB", RFC 2863, June 2000. [RFC3688] Mealling, M., "The IETF XML Registry", RFC 3688, January 2004. [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) Protocol Version 1.2", RFC 5246, August 2008. [RFC6020] Bjorklund, M., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, October 2010. [RFC6241] Enns, R., Bjorklund, M., Schoenwaelder, J., and A. Bierman, "Network Configuration Protocol (NETCONF)", RFC 6241, June 2011. [RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, June 2011. [RFC6536] Bierman, A. and M. Bjorklund, "Network Configuration Protocol (NETCONF) Access Control Model", RFC 6536, March 2012. [RFC6991] Schoenwaelder, J., "Common YANG Data Types", RFC 6991, July 2013. [RFC7950] Bjorklund, M., "The YANG 1.1 Data Modeling Language", RFC 7950, August 2016. [RFC7951] Lhotka, L., "JSON Encoding of Data Modeled with YANG", RFC 7951, August 2016. [RFC8294] Liu, X., Qu, Y., Lindem, A., Hopps, C., and L. Berger, "Common YANG Data Types for the Routing Area", RFC 8294, December 2014. Clemm, et al. Expires June 19, 2018 [Page 18] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 12.2. Informative References [I-D.draft-acee-rtgwg-yang-rib-extend] Lindem, A. and Y. Qu, "YANG Data Model for RIB Extensions", I-D draft-acee-rtgwg-yang-rib-extend-05, October 2017. [I-D.draft-ietf-i2rs-usecase-reqs-summary] Hares, S. and M. Chen, "Summary of I2RS Use Case Requirements", I-D draft-ietf-i2rs-usecase-reqs-summary- 03, November 2016. [I-D.draft-ietf-netmod-yang-tree-diagrams] Bjorklund, M. and L. Berger, "YANG Tree Diagrams", I-D draft-ietf-netmod-yang-tree-diagrams, October 2017. [I-D.draft-ietf-teas-yang-te-topo] Liu, X., Bryskin, I., Beeram, V., Saad, T., Shah, H., and O. Gonzalez De Dios, "YANG Data Model for TE Topologies", I-D draft-ietf-teas-yang-te-topo-13, October 2017. [RFC7223] Bjorklund, M., "A YANG Data Model for Routing Management", RFC 7223, May 2014. [RFC8022] Lhotka, L. and A. Lindem, "A YANG Data Model for Routing Management", RFC 8022, November 2016. [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, January 2017. [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", RFC 8174, May 2017. [RFC8242] Haas, J. and S. Hares, "I2RS Ephemeral State Requirements", RFC 8242, September 2017. Clemm, et al. Expires June 19, 2018 [Page 19] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 Appendix A. Companion YANG model for non-NMDA compliant implementations The YANG module ietf-l3-unicast-topology defined in this document augments two modules, ietf-network and ietf-network-topology, that are designed to be used in conjunction with implementations that support the Network Management Datastore Architecture (NMDA) defined in [I-D.draft-ietf-netmod-revised-datastores]. In order to allow implementations to use the model even in cases when NMDA is not supported, a set of companion modules have been defined that represent a state model of networks and network topologies, ietf- network-state and ietf-network-topology-state, respectively. In order to be able to use the model for layer 3 topologies defined in this in this document in conjunction with non-NMDA compliant implementations, a corresponding companion module needs to be introduced as well. This companion module, ietf-l3-unicast-topology- state, mirrors ietf-l3-unicast-topology. However, the module augments ietf-network-state and ietf-network-topology-state (instead of ietf-network and ietf-network-topology) and all of its data nodes are non-configurable. Similar considerations apply for any modules that augment ietf-l3- unicast-topology, such as the example modules defined in see Appendix B, example-ospf-topology. For non-NMDA compliant implementations, companion modules will need to be introduced that represent state information and are non-configurable, augmenting ietf-l3-unicast-topology-state instead of ietf-l3-unicast-topology. Because they served as examples only, companion modules for those examples are not given. Like ietf-network-state and ietf-network-topology-state, ietf-l3- unicast-topology SHOULD NOT be supported by implementations that support NMDA. It is for this reason that the module is defined in the Appendix. The definition of the module follows below. As the structure of the module mirrors that of its underlying module, the YANG tree is not depicted separately. file "ietf-l3-unicast-topology-state@2017-12-16.yang" module ietf-l3-unicast-topology-state { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-l3-unicast-topology-state"; prefix "l3t-s"; import ietf-network-state { prefix "nw-s"; } Clemm, et al. Expires June 19, 2018 [Page 20] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 import ietf-network-topology-state { prefix "nt-s"; } import ietf-l3-unicast-topology { prefix "l3t"; } organization "IETF I2RS (Interface to the Routing System) Working Group"; contact "WG Web: WG List: Editor: Alexander Clemm Editor: Jan Medved Editor: Robert Varga Editor: Xufeng Liu Editor: Nitin Bahadur Editor: Hariharan Ananthakrishnan "; description "This module defines a model for Layer 3 Unicast topology state, representing topology that is either learned, or topology that results from applying topology that has been configured per the ietf-l3-unicast-topology model, mirroring the corresponding data nodes in this model. The model mirrors ietf-l3-unicast-topology, but contains only read-only state data. The model is not needed when the underlying implementation infrastructure supports the Network Management Datastore Architecture (NMDA). Copyright (c) 2017 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 Simplified BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info). This version of this YANG module is part of draft-ietf-i2rs-yang-l3-topology-16; see the RFC itself for full legal notices. NOTE TO RFC EDITOR: Please replace above reference to draft-ietf-i2rs-yang-l3-topology-16 with RFC Clemm, et al. Expires June 19, 2018 [Page 21] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 number when published (i.e. RFC xxxx)."; revision "2017-12-16" { description "Initial revision. NOTE TO RFC EDITOR: Please replace the following reference to draft-ietf-i2rs-yang-l3-topology-16 with RFC number when published (i.e. RFC xxxx)."; reference "draft-ietf-i2rs-yang-l3-topology-16"; } augment "/nw-s:networks/nw-s:network/nw-s:network-types" { description "Introduce new network type for L3 unicast topology"; uses l3t:l3-unicast-topology-type; } augment "/nw-s:networks/nw-s:network" { when "nw-s:network-types/l3t-s:l3-unicast-topology" { description "Augmentation parameters apply only for networks with L3 unicast topology"; } description "L3 unicast for the network as a whole"; uses l3t:l3-topology-attributes; } augment "/nw-s:networks/nw-s:network/nw-s:node" { when "../nw-s:network-types/l3t-s:l3-unicast-topology" { description "Augmentation parameters apply only for networks with L3 unicast topology"; } description "L3 unicast node level attributes "; uses l3t:l3-node-attributes; } augment "/nw-s:networks/nw-s:network/nt-s:link" { when "../nw-s:network-types/l3t-s:l3-unicast-topology" { description "Augmentation parameters apply only for networks with L3 unicast topology"; } description "Augment topology link attributes"; uses l3t:l3-link-attributes; } augment "/nw-s:networks/nw-s:network/nw-s:node/" +"nt-s:termination-point" { when "../../nw-s:network-types/l3t-s:l3-unicast-topology" { Clemm, et al. Expires June 19, 2018 [Page 22] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 description "Augmentation parameters apply only for networks with L3 unicast topology"; } description "Augment topology termination point configuration"; uses l3t:l3-termination-point-attributes; } notification l3-node-event { description "Notification event for L3 node"; leaf l3-event-type { type l3t:l3-event-type; description "Event type"; } uses nw-s:node-ref; uses l3t:l3-unicast-topology-type; uses l3t:l3-node-attributes; } notification l3-link-event { description "Notification event for L3 link"; leaf l3-event-type { type l3t:l3-event-type; description "Event type"; } uses nt-s:link-ref; uses l3t:l3-unicast-topology-type; uses l3t:l3-link-attributes; } notification l3-prefix-event { description "Notification event for L3 prefix"; leaf l3-event-type { type l3t:l3-event-type; description "Event type"; } uses nw-s:node-ref; uses l3t:l3-unicast-topology-type; container prefix { description "Containing L3 prefix attributes"; uses l3t:l3-prefix-attributes; } } notification termination-point-event { Clemm, et al. Expires June 19, 2018 [Page 23] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 description "Notification event for L3 termination point"; leaf l3-event-type { type l3t:l3-event-type; description "Event type"; } uses nt-s:tp-ref; uses l3t:l3-unicast-topology-type; uses l3t:l3-termination-point-attributes; } } Appendix B. Extending the Model The model can be extended for specific Layer 3 Unicast types. Examples include OSPF and IS-IS topologies. In the following, one additional YANG module is introduced that define simple topology model for OSPF. This module is intended to serve as an example that illustrates how the general topology model can be refined across multiple levels. It does not constitute full-fledged OSPF topology model which may be more comprehensive and refined than the model that is described here. B.1. Example OSPF Topology B.1.1. Model Overview The following model shows how the Layer 3 Unicast topology model can be extended, in this case to cover OSFP topologies. For this purpose, a set of augmentations are introduced in a separate YANG module, "example-ospf-topology", whose structure is depicted in the following diagram. As before, the notation syntax follows [I-D.draft-ietf-netmod-yang-tree-diagrams]. Clemm, et al. Expires June 19, 2018 [Page 24] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 module: example-ospf-topology augment /nw:networks/nw:network/nw:network-types/l3t:l3-unicast-topology: +--rw ospf! augment /nw:networks/nw:network/l3t:l3-topology-attributes: +--rw ospf-topology-attributes +--rw area-id? area-id-type augment /nw:networks/nw:network/nw:node/l3t:l3-node-attributes: +--rw ospf-node-attributes +--rw (router-type)? | +--:(abr) | | +--rw abr? empty | +--:(asbr) | | +--rw asbr? empty | +--:(internal) | | +--rw internal? empty | +--:(pseudonode) | +--rw pseudonode? empty +--rw dr-interface-id? uint32 augment /nw:networks/nw:network/nt:link/l3t:l3-link-attributes: +--rw ospf-link-attributes augment /l3t:l3-node-event: +---- ospf! +---- ospf-node-attributes +---- (router-type)? | +--:(abr) | | +---- abr? empty | +--:(asbr) | | +---- asbr? empty | +--:(internal) | | +---- internal? empty | +--:(pseudonode) | +---- pseudonode? empty +---- dr-interface-id? uint32 augment /l3t:l3-link-event: +---- ospf! +---- ospf-link-attributes The module augments "ietf-l3-unicast-topology" as follows: o A new topology type for an OSPF topology is introduced. o Additional topology attributes are defined in a new grouping which augments l3-topology-attributes of the ietf-l3-unicast-topology module. The attributes include an OSPF area-id identifying the OSPF area. Clemm, et al. Expires June 19, 2018 [Page 25] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 o Additional data objects for nodes are introduced by augmenting the l3-node-attributes of the l3-unicast-topology module. New objects include router-type and dr-interface-id for pseudonodes. o Links are augmented with ospf link attributes. In addition, the module extends notifications for events concerning Layer 3 nodes and links with OSPF attributes. It should be noted that the model defined here represents topology and is intended as an example. It does not define how to configure OSPF routers or interfaces. B.1.2. OSPF Topology YANG Module The OSPF Topology YANG Module is specified below. As mentioned, the module is intended as an example for how the Layer 3 Unicast topology model can be extended to cover OSFP topologies, but it is not normative. Accordingly, the module is not delimited with CODE BEGINS and CODE ENDS tags. file "example-ospf-topology@2017-12-16.yang" module example-ospf-topology { yang-version 1.1; namespace "urn:example:example-ospf-topology"; prefix "ex-ospft"; import ietf-yang-types { prefix "yang"; } import ietf-network { prefix "nw"; } import ietf-network-topology { prefix "nt"; } import ietf-l3-unicast-topology { prefix "l3t"; } description "This module is intended as an example for how the Layer 3 Unicast topology model can be extended to cover OSFP topologies."; typedef area-id-type { type yang:dotted-quad; description "Area ID type."; } grouping ospf-topology-type { Clemm, et al. Expires June 19, 2018 [Page 26] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 description "Identifies the OSPF topology type."; container ospf { presence "indicates OSPF Topology"; description "Its presence identifies the OSPF topology type."; } } augment "/nw:networks/nw:network/nw:network-types/" + "l3t:l3-unicast-topology" { description "Defines the OSPF topology type."; uses ospf-topology-type; } augment "/nw:networks/nw:network/l3t:l3-topology-attributes" { when "../nw:network-types/l3t:l3-unicast-topology/" + "ex-ospft:ospf" { description "Augment only for OSPF topology"; } description "Augment topology configuration"; container ospf-topology-attributes { description "Containing topology attributes"; leaf area-id { type area-id-type; description "OSPF area ID"; } } } augment "/nw:networks/nw:network/nw:node/l3t:l3-node-attributes" { when "../../nw:network-types/l3t:l3-unicast-topology/" + "ex-ospft:ospf" { description "Augment only for OSPF topology"; } description "Augment node configuration"; uses ospf-node-attributes; } augment "/nw:networks/nw:network/nt:link/l3t:l3-link-attributes" { when "../../nw:network-types/l3t:l3-unicast-topology/" + "ex-ospft:ospf" { description "Augment only for OSPF topology"; } Clemm, et al. Expires June 19, 2018 [Page 27] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 description "Augment link configuration"; uses ospf-link-attributes; } grouping ospf-node-attributes { description "OSPF node scope attributes"; container ospf-node-attributes { description "Containing node attributes"; choice router-type { description "Indicates router type"; case abr { leaf abr { type empty; description "The node is ABR"; } } case asbr { leaf asbr { type empty; description "The node is ASBR"; } } case internal { leaf internal { type empty; description "The node is internal"; } } case pseudonode { leaf pseudonode { type empty; description "The node is pseudonode"; } } } leaf dr-interface-id { when "../pseudonode" { description "Valid only for pseudonode"; } type uint32; Clemm, et al. Expires June 19, 2018 [Page 28] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 default "0"; description "For pseudonodes, DR interface-id"; } } } grouping ospf-link-attributes { description "OSPF link scope attributes"; container ospf-link-attributes { description "Containing OSPF link attributes"; } } // ospf-link-attributes augment "/l3t:l3-node-event" { description "OSPF node event"; uses ospf-topology-type; uses ospf-node-attributes; } augment "/l3t:l3-link-event" { description "OSPF link event"; uses ospf-topology-type; uses ospf-link-attributes; } } Appendix C. An Example This section contains an example of an instance data tree in JSON encoding [RFC7951]. The example instantiates ietf-l3-unicast- topology for the topology that is depicted in the following diagram. There are three nodes, D1, D2, and D3. D1 has three termination points, 1-0-1, 1-2-1, and 1-3-1. D2 has three termination points as well, 2-1-1, 2-0-1, and 2-3-1. D3 has two termination points, 3-1-1 and 3-2-1. In addition there are six links, two between each pair of nodes with one going in each direction. Clemm, et al. Expires June 19, 2018 [Page 29] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 +------------+ +------------+ | D1 | | D2 | /-\ /-\ /-\ /-\ | | 1-0-1 | |---------------->| | 2-1-1 | | | | 1-2-1 | |<----------------| | 2-0-1 | | \-/ 1-3-1 \-/ \-/ 2-3-1 \-/ | /----\ | | /----\ | +---| |---+ +---| |---+ \----/ \----/ A | A | | | | | | | | | | | +------------+ | | | | | D3 | | | | | /-\ /-\ | | | +----->| | 3-1-1 | |-------+ | +---------| | 3-2-1 | |<---------+ \-/ \-/ | | +------------+ Figure 2: A network topology example The corresponding instance data tree is depicted below: { "ietf-network:networks": { "network": [ { "network-types": { "ietf-l3-unicast-topology:l3-unicast-topology": {} }, "network-id": "l3-topo-example", "node": [ { "node-id": "D1", "termination-point": [ { "tp-id": "1-0-1", "ietf-l3-unicast-topology:l3-termination-point-attributes": { "unnumbered-id:": 101 } }, { "tp-id": "1-2-1", "ietf-l3-unicast-topology:l3-termination-point-attributes": { "unnumbered-id:": 121 Clemm, et al. Expires June 19, 2018 [Page 30] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 } }, { "tp-id": "1-3-1", "ietf-l3-unicast-topology:l3-termination-point-attributes": { "unnumbered-id:": 131 } } ], "ietf-l3-unicast-topology:l3-node-attributes": { "router-id": ["203.0.113.1"] } }, { "node-id": "D2", "termination-point": [ { "tp-id": "2-0-1", "ietf-l3-unicast-topology:l3-termination-point-attributes": { "unnumbered-id:": 201 } }, { "tp-id": "2-1-1", "ietf-l3-unicast-topology:l3-termination-point-attributes": { "unnumbered-id:": 211 } }, { "tp-id": "2-3-1", "ietf-l3-unicast-topology:l3-termination-point-attributes": { "unnumbered-id:": 231 } } ], "ietf-l3-unicast-topology:l3-node-attributes": { "router-id": ["203.0.113.2"] } }, { "node-id": "D3", "termination-point": [ { "tp-id": "3-1-1", "ietf-l3-unicast-topology:l3-termination-point-attributes": { "unnumbered-id:": 311 } }, Clemm, et al. Expires June 19, 2018 [Page 31] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 { "tp-id": "3-2-1", "ietf-l3-unicast-topology:l3-termination-point-attributes": { "unnumbered-id:": 321 } } ], "ietf-l3-unicast-topology:l3-node-attributes": { "router-id": ["203.0.113.3"] } } ], "ietf-network-topology:link": [ { "link-id": "D1,1-2-1,D2,2-1-1", "destination": { "source-node": "D1", "source-tp": "1-2-1" } "destination": { "dest-node": "D2", "dest-tp": "2-1-1" }, "ietf-l3-unicast-topology:l3-link-attributes": { "metric1": "100" } }, { "link-id": "D2,2-1-1,D1,1-2-1", "destination": { "source-node": "D2", "source-tp": "2-1-1" } "destination": { "dest-node": "D1", "dest-tp": "1-2-1" }, "ietf-l3-unicast-topology:l3-link-attributes": { "metric1": "100" } }, { "link-id": "D1,1-3-1,D3,3-1-1", "destination": { "source-node": "D1", "source-tp": "1-3-1" } "destination": { Clemm, et al. Expires June 19, 2018 [Page 32] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 "dest-node": "D3", "dest-tp": "3-1-1" }, "ietf-l3-unicast-topology:l3-link-attributes": { "metric1": "100" } }, { "link-id": "D3,3-1-1,D1,1-3-1", "destination": { "source-node": "D3", "source-tp": "3-1-1" } "destination": { "dest-node": "D1", "dest-tp": "1-3-1" }, "ietf-l3-unicast-topology:l3-link-attributes": { "metric1": "100" } }, { "link-id": "D2,2-3-1,D3,3-2-1", "destination": { "source-node": "D2", "source-tp": "2-3-1" } "destination": { "dest-node": "D3", "dest-tp": "3-2-1" }, "ietf-l3-unicast-topology:l3-link-attributes": { "metric1": "100" } }, { "link-id": "D3,3-2-1,D2,2-3-1", "destination": { "source-node": "D3", "source-tp": "3-2-1" } "destination": { "dest-node": "D2", "dest-tp": "2-3-1" }, "ietf-l3-unicast-topology:l3-link-attributes": { "metric1": "100" } Clemm, et al. Expires June 19, 2018 [Page 33] Internet-Draft draft-ietf-i2rs-yang-l3-topology-16.txt December 2017 } ] } ] } } Figure 3: Instance data tree Authors' Addresses Alexander Clemm Huawei USA EMail: ludwig@clemm.org Jan Medved Cisco EMail: jmedved@cisco.com Robert Varga Pantheon Technologies SRO EMail: robert.varga@pantheon.tech Xufeng Liu Jabil EMail: Xufeng_Liu@jabil.com Hariharan Ananthakrishnan Packet Design EMail: hari@packetdesign.com Nitin Bahadur Bracket Computing EMail: nitin_bahadur@yahoo.com Clemm, et al. Expires June 19, 2018 [Page 34]