| 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
This document defines a YANG data model for layer 3 network topologies.
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 (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 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.
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.
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.
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.
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])
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]
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.
+-----------------------------+
| +-----------------------+ |
| | 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.
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.
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:
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.
<CODE BEGINS> 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: <http://tools.ietf.org/wg/i2rs/>
WG List: <mailto:i2rs@ietf.org>
Editor: Alexander Clemm
<mailto:ludwig@clemm.org>
Editor: Jan Medved
<mailto:jmedved@cisco.com>
Editor: Robert Varga
<mailto:robert.varga@pantheon.tech>
Editor: Xufeng Liu
<mailto:xliu@kuatrotech.com>
Editor: Nitin Bahadur
<mailto:nitin_bahadur@yahoo.com>
Editor: Hariharan Ananthakrishnan
<mailto:hari@packetdesign.com>";
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
"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";
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;
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";
}
}
}
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.";
}
}
}
}
}
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
"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;
uses l3-termination-point-attributes;
}
}
<CODE ENDS>
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.
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
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)
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 <operational> 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:
The model presented in this document was contributed to by more people than can be listed on the author list. Additional contributors include:
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.
| [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. |
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.
<CODE BEGINS> 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";
}
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: <http://tools.ietf.org/wg/i2rs/>
WG List: <mailto:i2rs@ietf.org>
Editor: Alexander Clemm
<mailto:ludwig@clemm.org>
Editor: Jan Medved
<mailto:jmedved@cisco.com>
Editor: Robert Varga
<mailto:robert.varga@pantheon.tech>
Editor: Xufeng Liu
<mailto:xliu@kuatrotech.com>
Editor: Nitin Bahadur
<mailto:nitin_bahadur@yahoo.com>
Editor: Hariharan Ananthakrishnan
<mailto:hari@packetdesign.com>";
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
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" {
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 {
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;
}
}
<CODE ENDS>
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.
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].
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:
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.
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 {
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";
}
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;
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;
}
}
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.
+------------+ +------------+
| 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
}
},
{
"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
}
},
{
"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": {
"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"
}
}
]
}
]
}
}
Figure 3: Instance data tree