OPSAWG Q. Wu, Ed.
Internet-Draft Huawei
Intended status: Informational M. Boucadair, Ed.
Expires: December 16, 2020 Orange
D. Lopez
Telefonica I+D
C. Xie
China Telecom
L. Geng
China Mobile
June 14, 2020
A Framework for Automating Service and Network Management with YANG
draft-ietf-opsawg-model-automation-framework-04
Abstract
Data models provide a programmatic approach to represent services and
networks. Concretely, they can be used to derive configuration
information for network and service components, and state information
that will be monitored and tracked. Data models can be used during
the service and network management life cycle, such as service
instantiation, provisioning, optimization, monitoring, diagnostic,
and assurance. Data models are also instrumental in the automation
of network management, and they can provide closed-loop control for
adaptive and deterministic service creation, delivery, and
maintenance.
This document describes an architecture for service and network
management automation that takes advantage of YANG modeling
technologies. This architecture is drawn from a Network Operator
perspective irrespective of the origin of a data module; it can thus
accommodate modules that are developed outside the IETF.
Status of This Memo
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and may be updated, replaced, or obsoleted by other documents at any
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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 December 16, 2020.
Copyright Notice
Copyright (c) 2020 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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology and Acronyms . . . . . . . . . . . . . . . . . . 5
2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
2.2. Acronyms . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Architectural Concepts and Goals . . . . . . . . . . . . . . 6
3.1. Data Models: Layering and Representation . . . . . . . . 6
3.2. Automation of Service Delivery Procedures . . . . . . . . 9
3.3. Service Fullfillment Automation . . . . . . . . . . . . . 10
3.4. YANG Modules Integration . . . . . . . . . . . . . . . . 10
4. Functional Bocks and Interactions . . . . . . . . . . . . . . 11
4.1. Service Lifecycle Management Procedure . . . . . . . . . 12
4.1.1. Service Exposure . . . . . . . . . . . . . . . . . . 13
4.1.2. Service Creation/Modification . . . . . . . . . . . . 13
4.1.3. Service Optimization . . . . . . . . . . . . . . . . 13
4.1.4. Service Diagnosis . . . . . . . . . . . . . . . . . . 14
4.1.5. Service Decommission . . . . . . . . . . . . . . . . 14
4.2. Service Fullfillment Management Procedure . . . . . . . . 14
4.2.1. Intended Configuration Provision . . . . . . . . . . 15
4.2.2. Configuration Validation . . . . . . . . . . . . . . 15
4.2.3. Performance Monitoring/Model-driven Telemetry . . . . 16
4.2.4. Fault Diagnostic . . . . . . . . . . . . . . . . . . 16
4.3. Multi-Layer/Multi-Domain Service Mapping . . . . . . . . 16
4.4. Service Decomposing . . . . . . . . . . . . . . . . . . . 17
5. YANG Data Model Integration Examples . . . . . . . . . . . . 17
5.1. L2VPN/L3VPN Service Delivery . . . . . . . . . . . . . . 17
5.2. VN Lifecycle Management . . . . . . . . . . . . . . . . . 19
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5.3. Event-based Telemetry in the Device Self Management . . . 20
6. Security Considerations . . . . . . . . . . . . . . . . . . . 21
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 22
9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 22
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 23
10.1. Normative References . . . . . . . . . . . . . . . . . . 23
10.2. Informative References . . . . . . . . . . . . . . . . . 24
Appendix A. Layered YANG Modules Examples Overview . . . . . . . 32
A.1. Service Models: Definition and Samples . . . . . . . . . 32
A.2. Network Models: Samples . . . . . . . . . . . . . . . . . 32
A.3. Device Models: Samples . . . . . . . . . . . . . . . . . 35
A.3.1. Model Composition . . . . . . . . . . . . . . . . . . 37
A.3.2. Device Models: Samples . . . . . . . . . . . . . . . 37
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 40
1. Introduction
Service management systems usually comprise service activation/
provision and service operation. Current service delivery
procedures, from the processing of customer's requirements and orders
to service delivery and operation, typically assume the manipulation
of data sequentially into multiple OSS/BSS applications that may be
managed by different departments within the service provider's
organization (e.g., billing factory, design factory, network
operation center). In addition, many of these applications have been
developed in-house over the years and operate in a silo mode:
o The lack of standard data input/output (i.e., data model) raises
many challenges in system integration and often results in manual
configuration tasks.
o Service fulfillment systems might have a limited visibility on the
network state and therefore have slow response to network changes.
Software Defined Networking (SDN) becomes crucial to address these
challenges. SDN techniques are meant to automate the overall service
delivery procedures and typically rely upon standard data models.
These models are used to not only reflect service providers' savoir-
faire, but also to dynamically instantiate and enforce a set of
service-inferred policies that best accommodate what has been defined
and possibly negotiated with the customer. [RFC7149] provides a
first tentative attempt to rationalize that service provider's view
on the SDN space by identifying concrete technical domains that need
to be considered and for which solutions can be provided:
o Techniques for the dynamic discovery of topology, devices, and
capabilities, along with relevant information and data models that
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are meant to precisely document such topology, devices, and their
capabilities.
o Techniques for exposing network services [RFC8309] and their
characteristics.
o Techniques used by service-derived dynamic resource allocation and
policy enforcement schemes, so that networks can be programmed
accordingly.
o Dynamic feedback mechanisms that are meant to assess how
efficiently a given policy (or a set thereof) is enforced from a
service fulfillment and assurance perspectives.
Models are key for each of the aforementioned four technical items.
Service and network management automation is an important step to
improve the agility of network operations. Models are also important
to ease integrating multi-vendor solutions.
YANG [RFC7950] module developers have taken both top-down and bottom-
up approaches to develop modules [RFC8199] and to establish a mapping
between a network technology and customer requirements at the top or
abstracting common constructs from various network technologies at
the bottom. At the time of writing this document (2020), there are
many data models including configuration and service models that have
been specified or are being specified by the IETF. They cover many
of the networking protocols and techniques. However, how these
models work together to configure a device, manage a set of devices
involved in a service, or provide a service is something that is not
currently documented either within the IETF or other Standards
Development Organizations (SDOs).
This document describes an architectural framework for service and
network management automation (Section 3) that takes advantage of
YANG modeling technologies and investigates how different layer YANG
data models interact with each other (e.g., service mapping, model
composing) in the context of service delivery and fulfillment
(Section 4).
This framework is drawn from a Network Operator perspective
irrespective of the origin of a data module; it can accommodate
modules that are developed outside the IETF.
The document identifies a list of use cases to exemplify the proposed
approach (Section 5), but it does not claim nor aim to be exhaustive.
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2. Terminology and Acronyms
2.1. Terminology
The following terms are defined in [RFC8309][RFC8199] and are not
redefined here:
o Network Operator
o Customer
o Service
o Data Model
o Service Model
o Network Element Module
In addition, the document makes use of the following terms:
Network Model: Describes a network level abstraction (or a subset of
aspects of a network infrastructure), including devices and their
subsystems, and relevant protocols operating at the link and
network layers across multiple devices. This model corresponds to
the Network Configuration Model discussed in [RFC8309].
It can be used by a Network Operator to allocate resources (e.g.,
tunnel resource, topology resource) for the service or schedule
resources to meet the service requirements defined in a Service
Model.
Device Model: Refers to the Network Element YANG data model
described in [RFC8199] or the Device Configuration Model discussed
in [RFC8309].
Device Models are also used to refer to model a function embedded
in a device (e.g., Network Address Translation (NAT) [RFC8512],
Access Control Lists (ACLs) [RFC8519]).
2.2. Acronyms
The following acronyms are used in the document:
ACL Access Control List
CE Customer Edge
ECA Event Condition Action
L2VPN Layer 2 Virtual Private Network
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L3VPN Layer 3 Virtual Private Network
NAT Network Address Translation
OAM Operations, Administration, and Maintenance
OWD One-Way Delay
PE Provider Edge
QoS Quality of Service
RD Route Distinguisher
RT Route Target
SDN Software Defined Networking
TE Traffic Engineering
VN Virtual Network
VPN Virtual Private Network
VRF Virtual Routing and Forwarding
3. Architectural Concepts and Goals
3.1. Data Models: Layering and Representation
As described in Section 2 of [RFC8199], layering of modules allows
for better reusability of lower-layer modules by higher-level modules
while limiting duplication of features across layers.
Data models can be classified into Service, Network, and Device
Models. Different Service Models may rely on the same set of Network
and/or Device Models.
Service Models traditionally follow top-down approach and are mostly
customer-facing YANG modules providing a common model construct for
higher level network services (e.g., Layer 3 Virtual Private Network
(L3VPN)). Such modules can be mapped to network technology-specific
modules at lower layers (e.g., tunnel, routing, Quality of Service
(QoS), security). For example, the service level can be used to
characterise the network service(s) to be ensured between service
nodes (ingress/egress) such as:
o the communication scope (pipe, hose, funnel, ...),
o the directionality (inbound/outbound),
o the traffic performance guarantees (One-Way Delay (OWD) [RFC7679],
One-Way Loss [RFC7680], ...),
o link capacity [RFC5136][I-D.ietf-ippm-capacity-metric-method],
o etc.
Figure 1 depicts the example of a VoIP service that relies upon
connectivity services offered by a Network Operator. In this
example, the VoIP service is offered to the Network Operator's
customers by Service Provider (SP1). In order to provide global VoIP
reachability, SP1 service site interconnects with other Service
Providers service sites typically by interconnecting Session Border
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Elements (SBEs) and Data Border Elements (DBEs) [RFC5486][RFC6406].
For other VoIP destinations, sessions are forwarded over the
Internet. These connectivity services can be captured in a YANG
Service Module that reflects the service attributes that are shown in
Figure 2. This example follows the IP Connectivity Provisioning
Profile template defined in [RFC7297].
,--,--,--. ,--,--,--.
,-' SP1 `-. ,-' SP2 `-.
( Service Site ) ( Service Site )
`-. ,-' `-. ,-'
`--'--'--' `--'--'--'
x | o * * |
(2)x | o * * |
,x-,--o-*-. (1) ,--,*-,--.
,-' x o * * * * * * * * * `-.
( x o +----( Internet )
User---(x x x o o o o o o o o o o o o o o o o o o
`-. ,-' `-. ,-' (3)
`--'--'--' `--'--'--'
Network Operator
**** (1) Inter-SP connectivity
xxxx (2) Customer to SP connectivity
oooo (3) SP to any destination connectivity
Figure 1: An Example of Service Connectivty Components
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Connectivity: Scope and Guarantees
(1) Inter-SP connectivity
- Pipe scope from the local to the remote SBE/DBE
- Full guarantees class
(2) Customer to SP connectivity
- Hose/Funnel scope connecting the local SBE/DBE
to the customer access points
- Full guarantees class
(3) SP to any destination connectivity
- Hose/Funnel scope from the local SBE/DBE to the
Internet gateway
- Delay guarantees class
Flow Identification
* Destination IP address (SBE, DBE)
* DSCP marking
Traffic Isolation
* VPN
Routing & Forwarding
* Routing rule to exclude some ASes from the inter-domain
paths
Notifications (including feedback)
* Statistics on aggregate traffic to adjust capacity
* Failures
* Planned maintenance operations
* Triggered by thresholds
Figure 2: Sample Attributes Captured in a Service Model
Network Models are mainly network resource-facing modules; they
describe various aspects of a network infrastructure, including
devices and their subsystems, and relevant protocols operating at the
link and network layers across multiple devices (e.g., network
topology and traffic-engineering tunnel modules).
Device (and function) Models usually follow a bottom-up approach and
are mostly technology-specific modules used to realize a service
(e.g., BGP, NAT).
Each level maintains a view of the supported YANG modules provided by
low-levels (see for example, Appendix A).
Figure 3 illustrates the overall layering model. The reader may
refer to Section 4 of [RFC8309] for an overview of "Orchestrator" and
"Controller" elements.
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+-----------------------------------------------------------------+
| +-----------------------+ |
| | Orchestrator | Hierarchy Abstraction |
| |+---------------------+| |
| || Service Modeling || Service Model |
| |+---------------------+| (Customer Oriented) |
| | | Scope: "1:1" Pipe model |
| | | Bidirectional |
| |+---------------------+| +-+ Capacity,OWD +-+ |
| ||Service Orchestration|| | +----------------+ | |
| |+---------------------+| +-+ +-+ |
| +-----------------------+ 1. Ingress 2. Egress |
| |
| |
| |
| +-----------------------+ Network Model |
| | Controller | (Operator Oriented) |
| |+---------------------+| +-+ +--+ +---+ +-+ |
| || Network Modeling || | | | | | | | | |
| |+---------------------+| | o----o--o----o---o---o | |
| |+---------------------+| +-+ +--+ +---+ +-+ |
| ||Network Orchestration|| src dst |
| |+---------------------+| L3VPN over TE |
| | | Instance Name/Access Interface |
| +-----------------------+ Protocol Type/Capacity/RD/RT/... |
| mapping for hop |
| |
| |
| +-----------------------+ |
| | Device | Device Model |
| |+--------------------+ | |
| || Device Modeling | | Interface add, BGP Peer, |
| |+--------------------+ | Tunnel ID, QoS/TE, ... |
| +-----------------------+ |
+-----------------------------------------------------------------+
Figure 3: Layering and Representation
3.2. Automation of Service Delivery Procedures
Service Models can be used by a Network Operator to expose its
services to its customers. Exposing such models allows to automate
the activation of service orders and thus the service delivery. One
or more monolithic Service Models can be used in the context of a
composite service activation request (e.g., delivery of a caching
infrastructure over a VPN). Such models are used to feed a decision-
making intelligence to adequately accommodate customer's needs.
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Also, such models may be used jointly with services that require
dynamic invocation. An example is provided by the service modules
defined by the DOTS WG to dynamically trigger requests to handle
Distributed Denial-of-Service (DDoS) attacks [RFC8783].
Network Models can be derived from Service Models and used to
provision, monitor, instantiate the service, and provide lifecycle
management of network resources. Doing so is meant to:
o expose network resources to customers (including other Network
Operators) to provide service fulfillment and assurance
o allow customers (or Network Operators) to dynamically adjust the
network resources based on service requirements as described in
Service Models (e.g., Figure 2) and the current network
performance information described in the telemetry modules.
3.3. Service Fullfillment Automation
To operate a service, the settings of the parameters in the Device
Models are derived from Service Models and/or Network Models and are
used to:
o Provision each involved network function/device with the proper
configuration information.
o Operate the network based on service requirements as described in
the Service Model(s) and local operational guidelines.
In addition, the operational state including configuration that is in
effect together with statistics should be exposed to upper layers to
provide better network visibility and assess to what extent the
derived low level modules are consistent with the upper level inputs.
Filters are enforced on the notifications that are communicated to
Service layers. The type and frequency of notifications may be
agreed in the Service Model.
Note that it is important to correlate telemetry data with
configuration data to be used for closed loops at the different
stages of service delivery, from resource allocation to service
operation, in particular.
3.4. YANG Modules Integration
To support top-down service delivery, YANG modules at different
levels or at the same level need to be integrated together for proper
service delivery (including, proper network setup). For example, the
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service parameters captured in Service Models need to be decomposed
into a set of configuration/notification parameters that may be
specific to one or more technologies; these technology-specific
parameters are grouped together to define technology-specific device
level models or network level models.
In addition, these technology-specific Device or Network Models can
be further integrated with each other using the schema mount
mechanism [RFC8528] to provision each involved network function/
device or each involved administrative domain to support newly added
module or features. A collection of Device Models integrated
together can be loaded and validated during the implementation time.
High-level policies can be defined at Service or Network Models
(e.g., "Autonomous System Number (ASN) Exclude" in the example
depicted in Figure 2). Device Models will be tweaked accordingly to
provide policy-based management. Policies can also be used for
telemetry automation, e.g., policies that contain conditions can
trigger the generation and pushing of new telemetry data.
Performance measurement telemetry can be used to provide service
assurance at Service and/or Network levels. Performance measurement
telemetry model can tie with Service or Network Models to monitor
network performance or Service Level Agreement.
4. Functional Bocks and Interactions
The architectural considerations described in Section 3 lead to the
architecture described in this section and illustrated in Figure 4.
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+------------------+
................. | |
Service level | |
V |
E2E E2E E2E E2E
Service --> Service ---------> Service -----> Service -----+
Exposure Creation ^ Optimization ^ Diagnosis |
/Modification | | |
| |Diff | V
Multi-layer | | E2E | E2E
Multi-domain | | Service | Service
Service Mapping| +------ Assurance --+ Decommission
| ^
................. |<-----------------+ |
Network level | | +-------+
V | |
Specific Specific |
Service --------> Service <--+ |
Creation ^ Optimization | |
/Modification | | |
| |Diff | |
| | Specific --+ |
Service | | Service |
Decomposing | +----- Assurance ----+
| ^
................. | | Aggregation
Device level | +------------+
V |
Service Intent |
Fulfillment Config ----> Config ----> Performance ----> Fault
Provision Validate Monitoring Diagnostic
Figure 4: Service and Network Lifecycle Management
4.1. Service Lifecycle Management Procedure
Service lifecycle management includes end-to-end service lifecycle
management at the service level and technology specific network
lifecycle management at the network level.
The end-to-end service lifecycle management is technology-independent
service management and spans across multiple administrative domain or
multiple layers while technology specific service lifecycle
management is technology domain specific or layer specific service
lifecycle management.
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4.1.1. Service Exposure
A service in the context of this document (sometimes called, Network
Service) is some form of connectivity between customer sites and the
Internet or between customer sites across the operator's network and
across the Internet.
Service exposure is used to capture services offered to customers
(ordering and order handling). One typical example is that a
customer can use a L3VPN Service Model (L3SM) to request L3VPN
service by providing the abstract technical characterization of the
intended service between customer sites.
Service Model catalogs can be created along to expose the various
services and the information needed to invoke/order a given service.
4.1.2. Service Creation/Modification
A customer is usually unaware of the technology that the Network
Operator has available to deliver the service, so the customer does
not make requests specific to the underlying technology but is
limited to making requests specific to the service that is to be
delivered. This service request can be issued using a Service Model.
Upon receiving a service request, and assuming that appropriate
authentication and authorization checks have been made, the service
orchestrator/management system should verify whether the service
requirements in the service request can be met (i.e., whether there
is sufficient resources that can be allocated with the requested
guarantees).
If the request is accepted, the service orchestrator/management
system maps such service request to its view. This view can be
described as a technology specific network model or a set of
technology specific Device Models and this mapping may include a
choice of which networks and technologies to use depending on which
service features have been requested.
In addition, a customer may require to change the underlying network
infrastructure to adapt to new customer's needs and service
requirements. This service modification can be issued following the
same Service Model used by the service request.
4.1.3. Service Optimization
Service optimization is a technique that gets the configuration of
the network updated due to network changes, incidents mitigation, or
new service requirements. One typical example is once a tunnel or a
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VPN is setup, Performance monitoring information or telemetry
information per tunnel (or per VPN) can be collected and fed into the
management system. If the network performance doesn't meet the
service requirements, the management system can create new VPN
policies capturing network service requirements and populate them
into the network.
Both network performance information and policies can be modelled
using YANG. With Policy-based management, self-configuration and
self-optimization behavior can be specified and implemented.
4.1.4. Service Diagnosis
Operations, Administration, and Maintenance (OAM) are important
networking functions for service diagnosis that allow Network
Operators to:
o monitor network communications (i.e., reachability verification
and Continuity Check)
o troubleshoot failures (i.e., fault verification and localization)
o monitor service-level agreements and performance (i.e.,
performance management)
When the network is down, service diagnosis should be in place to
pinpoint the problem and provide recommendations (or instructions)
for the network recovery.
The service diagnosis information can be modelled as technology-
independent Remote Procedure Call (RPC) operations for OAM protocols
and technology-independent abstraction of key OAM constructs for OAM
protocols [RFC8531][RFC8533]. These models can be used to provide
consistent configuration, reporting, and presentation for the OAM
mechanisms used to manage the network.
4.1.5. Service Decommission
Service decommission allows a customer to stop the service by
removing the service from active status and thus releasing the
network resources that were allocated to the service. Customers can
also use the Service Model to withdraw the registration to a service.
4.2. Service Fullfillment Management Procedure
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4.2.1. Intended Configuration Provision
Intended configuration at the device level is derived from Network
Models at the network level or Service Model at the service level and
represents the configuration that the system attempts to apply. Take
L3SM as a Service Model example to deliver a L3VPN service, we need
to map the L3VPN service view defined in the Service Model into
detailed intended configuration view defined by specific
configuration models for network elements, configuration information
includes:
o Virtual Routing and Forwarding (VRF) definition, including VPN
policy expression
o Physical Interface(s)
o IP layer (IPv4, IPv6)
o QoS features such as classification, profiles, etc.
o Routing protocols: support of configuration of all protocols
listed in a service request, as well as routing policies
associated with those protocols.
o Multicast support
o Address sharing (e.g., NAT)
o Security
These specific configuration models can be used to configure Provider
Edge (PE) and Customer Edge (CE) devices within a site, e.g., a BGP
policy model can be used to establish VPN membership between sites
and VPN Service Topology.
4.2.2. Configuration Validation
Configuration validation is used to validate intended configuration
and ensure the configuration take effect.
For example, a customer creates an interface "eth-0/0/0" but the
interface does not physically exist at this point, then configuration
data appears in the <intended> status but does not appear in
<operational> datastore.
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4.2.3. Performance Monitoring/Model-driven Telemetry
When configuration is in effect in the device, <operational>
datastore holds the complete operational state of the device
including learned, system, default configuration, and system state.
However, the configurations and state of a particular device does not
have the visibility to the whole network or information of the flow
packets are going to take through the entire network. Therefore it
becomes more difficult to operate the network without understanding
the current status of the network.
The management system should subscribe to updates of a YANG datastore
in all the network devices for performance monitoring purpose and
build a full topological visibility of the network by aggregating
(and filtering) these operational state from different sources.
4.2.4. Fault Diagnostic
When configuration is in effect in the device, some devices may be
mis-configured (e.g.,device links are not consistent in both sides of
the network connection), network resources be mis-allocated and
services may be negatively affected without knowing what is going on
in the network.
Technology-dependent nodes and RPC commands are defined in
technology-specific YANG data models which can use and extend the
base model described in Section 4.1.4 to deal with these issues.
These RPC commands received in the technology-dependent node can be
used to trigger technology-specific OAM message exchanges for fault
verification and fault isolation For example, TRILL Multicast Tree
Verification (MTV) RPC command [I-D.ietf-trill-yang-oam] can be used
to trigger Multi-Destination Tree Verification Message defined in
[RFC7455] to verify TRILL distribution tree integrity.
4.3. Multi-Layer/Multi-Domain Service Mapping
Multi-layer/Multi-domain Service Mapping allows to map an end-to-end
abstract view of the service segmented at different layers or
different administrative domains into domain-specific view.
One example is to map service parameters in L3VPN service model into
configuration parameters such as Route Distinguisher (RD), Route
Target (RT), and VRF in L3VPN network model.
Another example is to map service parameters in L3VPN service model
into Traffic Engineered (TE) tunnel parameter (e.g., Tunnel ID) in TE
model and Virtual Network (VN) parameters (e.g., Access Point (AP)
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list, VN members) in the YANG data model for VN operation
[I-D.ietf-teas-actn-vn-yang].
4.4. Service Decomposing
Service Decomposing allows to decompose service model at the service
level or network model at the network level into a set of device/
function models at the device level. These Device Models may be tied
to specific device types or classified into a collection of related
YANG modules based on service types and features offered, and load at
the implementation time before configuration is loaded and validated.
5. YANG Data Model Integration Examples
The following subsections provides some data models integration
examples.
5.1. L2VPN/L3VPN Service Delivery
In reference to Figure 5, the following steps are performed to
deliver the L3VPN service within the network management automation
architecture defined in this document:
1. The Customer requests to create two sites (as per service
creation operation in Section 4.2.1) relying upon a L3SM Service
model with each having one network access connectivity, for
example:
* Site A: Network-Access A, Link Capacity = 20 Mbps, for class
"foo", guaranteed-capacity-percent = 10, average-One-Way-Delay
= 70 ms.
* Site B: Network-Access B, Link Capacity = 30 Mbps, for class
"foo1", guaranteed-capacity-percent = 15, average-One-Way-
Delay = 60 ms.
2. The Orchestrator extracts the service parameters from the L3SM
model. Then, it uses them as input to translate ("service
mapping operation" in Section 4.4) them into an orchestrated
configuration of network elements (e.g., RD, RT, VRF) that are
part of the L3VPN Network YANG Model specified in
[I-D.ietf-opsawg-l3sm-l3nm].
3. The Controller takes orchestrated configuration parameters in the
L3NM network model and translates them into orchestrated
("service decomposing operation" in ) configuration of network
elements that are part of, e.g., BGP, QoS, Network Instance
model, IP management, and interface models.
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[I-D.ogondio-opsawg-uni-topology] can be used for representing,
managing, and controlling the User Network Interface (UNI) topology.
L3SM |
Service |
Model |
+----------------------+--------------------------+
| +--------V--------+ |
| | Service Mapping | |
| +--------+--------+ |
| Orchestrator | |
+----------------------+--------------------------+
L3NM | ^ UNI Topology Model
Network| |
Model | |
+----------------------+--------------------------+
| +----------V-----------+ |
| | Service Decomposing | |
| +---++--------------++-+ |
| || || |
| Controller || || |
+---------------++--------------++----------------+
|| ||
|| BGP, ||
|| QoS, ||
|| Interface, ||
+------------+| NI, |+--------------+
| | IP | |
+--+--+ +--+--+ +--+--+ +--+--+
| CE1 +-------+ PE1 | | PE2 +---------+ CE2 |
+-----+ +-----+ +-----+ +-----+
Figure 5: L3VPN Service Delivery Example (Current)
L3NM inherits some of data elements from the L3SM. Nevertheless, the
L3NM does not expose some information to the above layer such as the
capabilities of an underlying network (which can be used to drive
service order handling) or notifications (to notify subscribers about
specific events or degradations as per agreed SLAs). Some of this
information can be provided using, e.g.,
[I-D.www-bess-yang-vpn-service-pm]. A target overall model is
depicted in Figure 6.
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L3SM | ^
Service | | Notifications
Model | |
+----------------------+--------------------------+
| +--------V--------+ |
| | Service Mapping | |
| +--------+--------+ |
| Orchestrator | |
+----------------------+--------------------------+
L3NM | ^ UNI Topology Model
Network| | L3NM Notifications
Model | | L3NM Capabilities
+----------------------+--------------------------+
| +----------V-----------+ |
| | Service Decomposing | |
| +---++--------------++-+ |
| || || |
| Controller || || |
+---------------++--------------++----------------+
|| ||
|| BGP, ||
|| QoS, ||
|| Interface, ||
+------------+| NI, |+--------------+
| | IP | |
+--+--+ +--+--+ +--+--+ +--+--+
| CE1 +-------+ PE1 | | PE2 +---------+ CE2 |
+-----+ +-----+ +-----+ +-----+
Figure 6: L3VPN Service Delivery Example (Target)
Note that a similar analysis can be performed for Layer 2 VPNs
(L2VPNs). A L2VPN Service Model (L2SM) is defined in [RFC8466],
while the L2VPN Network YANG Model (L2NM) is specified in
[I-D.barguil-opsawg-l2sm-l2nm].
5.2. VN Lifecycle Management
In reference to Figure 7, the following steps are performed to
deliver the VN service within the network management automation
architecture defined in this document:
1. Customer requests (service exposure operation in Section 4.1.1)
to create 'VN' based on Access point, association between VN and
Access point, VN member defined in the VN YANG module.
2. The orchestrator creates the single abstract node topology based
on the information captured in an VN YANG module.
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3. The Customer exchanges connectivity-matrix on abstract node and
explicit path using TE topology model with the orchestrator.
This information can be used to instantiate VN and setup tunnels
between source and destination endpoints (service creation
operation in Section 4.1.2).
4. The telemetry model which augments the VN model and corresponding
TE tunnel model can be used to subscribe to performance
measurement data and notify all the parameter changes and network
performance change related to VN topology or Tunnel
[I-D.ietf-teas-actn-pm-telemetry-autonomics] and provide service
assurance (service optimization operation in Section 4.1.3).
|
VN |
Service |
Model |
+----------------------|--------------------------+
| Orchestrator | |
| +--------V--------+ |
| | Service Mapping | |
| +-----------------+ |
+----------------------+--------------------^-----+
TE | Telemetry
Tunnel | Model
Model | |
+----------------------V--------------------+-----+
| Controller |
| |
+-------------------------------------------------+
+-----+ +-----+ +-----+ +-----+
| CE1 +------+ PE1 | | PE2 +------+ CE2 |
+-----+ +-----+ +-----+ +-----+
Figure 7: A VN Service Delivery Example
5.3. Event-based Telemetry in the Device Self Management
In reference to Figure 8, the following steps are performed to
monitor state changes of managed objects or resources in a network
device and provide device self-management within the network
management automation architecture defined in this document:
1. To control which state a network device should be in or is
allowed to be in at any given time, a set of conditions and
actions are defined and correlated with network events (e.g.,
allow the NETCONF server to send updates only when the value
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exceeds a certain threshold for the first time, but not again
until the threshold is cleared), which constitute ECA policy or
an event-driven policy control logic that can be executed on the
device (e.g., [I-D.wwx-netmod-event-yang]).
2. To provide rapid autonomic response that can exhibit self-
management properties, the controller pushes the ECA policy to
the network device and delegates network control logic to the
network device.
3. The network device uses the ECA model to subscribe to the event
source, e.g., an event stream or datastore state data conveyed to
the server via YANG Push subscription, monitors state parameters,
and takes simple and instant actions when associated event
condition on state parameters is met. ECA notifications can be
generated as the result of actions based on event stream
subscription or datastore subscription (model-driven telemetry
operation discussed in Section 4.2.3).
+----------------+
| <----+
| Controller | |
+-------+--------+ |
| |
| |
ECA | | ECA
Model | | Notification
| |
| |
+------------V-------------+-----+
|Device | |
| +-------+ +---------+ +--+---+ |
| | Event +-> Event +->Event | |
| | Source| |Condition| |Action| |
| +-------+ +---------+ +------+ |
+--------------------------------+
Figure 8: Event-based Telemetry
6. Security Considerations
The YANG modules cited in this document define schema for data that
are designed to be accessed via network management protocols such as
NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer is
the secure transport layer, and the mandatory-to-implement secure
transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer
is HTTPS, and the mandatory-to-implement secure transport is TLS
[RFC8446].
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The NETCONF access control model [RFC8341] provides the means to
restrict access for particular NETCONF or RESTCONF users to a
preconfigured subset of all available NETCONF or RESTCONF protocol
operations and content.
Security considerations specific to each of the technologies and
protocols listed in the document are discussed in the specification
documents of each of these protocols.
Security considerations specific to this document are listed below:
o Create forwarding loops by mis-configuring the underlying network.
o Leak sensitive information: special care should be considered when
translating between the various layers in Section 4 or when
aggregating data retrieved from various sources. The Network
Operator must enforce means to protect privacy-related information
included in cutsomer-facing models.
o Some Service Models may include a traffic isolation clause,
appropriate technology-specific actions must be enforced to avoid
that traffic is accessible to non-authorized parties.
7. IANA Considerations
There are no IANA requests or assignments included in this document.
8. Acknowledgements
Thanks to Joe Clark, Greg Mirsky, Shunsuke Homma, Brian Carpenter,
and Adrian Farrel for the review.
9. Contributors
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Christian Jacquenet
Orange
Rennes, 35000
France
Email: Christian.jacquenet@orange.com
Luis Miguel Contreras Murillo
Telifonica
Email: luismiguel.contrerasmurillo@telefonica.com
Oscar Gonzalez de Dios
Telefonica
Madrid
ES
Email: oscar.gonzalezdedios@telefonica.com
Weiqiang Cheng
China Mobile
Email: chengweiqiang@chinamobile.com
Young Lee
Sung Kyun Kwan University
Email: younglee.tx@gmail.com
10. References
10.1. Normative References
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "Network Configuration Protocol
(NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
<https://www.rfc-editor.org/info/rfc6241>.
[RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure
Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
<https://www.rfc-editor.org/info/rfc6242>.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016,
<https://www.rfc-editor.org/info/rfc7950>.
[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
<https://www.rfc-editor.org/info/rfc8040>.
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[RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration
Access Control Model", STD 91, RFC 8341,
DOI 10.17487/RFC8341, March 2018,
<https://www.rfc-editor.org/info/rfc8341>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.
10.2. Informative References
[I-D.barguil-opsawg-l2sm-l2nm]
Barguil, S., Dios, O., Boucadair, M., Munoz, L., Jalil,
L., and J. Ma, "A Layer 2 VPN Network YANG Model", draft-
barguil-opsawg-l2sm-l2nm-02 (work in progress), May 2020.
[I-D.ietf-bess-evpn-yang]
Brissette, P., Shah, H., Hussain, I., Tiruveedhula, K.,
and J. Rabadan, "Yang Data Model for EVPN", draft-ietf-
bess-evpn-yang-07 (work in progress), March 2019.
[I-D.ietf-bess-l2vpn-yang]
Shah, H., Brissette, P., Chen, I., Hussain, I., Wen, B.,
and K. Tiruveedhula, "YANG Data Model for MPLS-based
L2VPN", draft-ietf-bess-l2vpn-yang-10 (work in progress),
July 2019.
[I-D.ietf-bess-l3vpn-yang]
Jain, D., Patel, K., Brissette, P., Li, Z., Zhuang, S.,
Liu, X., Haas, J., Esale, S., and B. Wen, "Yang Data Model
for BGP/MPLS L3 VPNs", draft-ietf-bess-l3vpn-yang-04 (work
in progress), October 2018.
[I-D.ietf-bess-mvpn-yang]
Liu, Y., Guo, F., Litkowski, S., Liu, X., Kebler, R., and
M. Sivakumar, "Yang Data Model for Multicast in MPLS/BGP
IP VPNs", draft-ietf-bess-mvpn-yang-02 (work in progress),
December 2019.
[I-D.ietf-bfd-yang]
Rahman, R., Zheng, L., Jethanandani, M., Pallagatti, S.,
and G. Mirsky, "YANG Data Model for Bidirectional
Forwarding Detection (BFD)", draft-ietf-bfd-yang-17 (work
in progress), August 2018.
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[I-D.ietf-i2rs-yang-l2-network-topology]
Dong, J., Wei, X., WU, Q., Boucadair, M., and A. Liu, "A
YANG Data Model for Layer-2 Network Topologies", draft-
ietf-i2rs-yang-l2-network-topology-13 (work in progress),
March 2020.
[I-D.ietf-idr-bgp-model]
Jethanandani, M., Patel, K., Hares, S., and J. Haas, "BGP
YANG Model for Service Provider Networks", draft-ietf-idr-
bgp-model-08 (work in progress), February 2020.
[I-D.ietf-ippm-capacity-metric-method]
Morton, A., Geib, R., and L. Ciavattone, "Metrics and
Methods for IP Capacity", draft-ietf-ippm-capacity-metric-
method-01 (work in progress), March 2020.
[I-D.ietf-ippm-stamp-yang]
Mirsky, G., Xiao, M., and W. Luo, "Simple Two-way Active
Measurement Protocol (STAMP) Data Model", draft-ietf-ippm-
stamp-yang-05 (work in progress), October 2019.
[I-D.ietf-ippm-twamp-yang]
Civil, R., Morton, A., Rahman, R., Jethanandani, M., and
K. Pentikousis, "Two-Way Active Measurement Protocol
(TWAMP) Data Model", draft-ietf-ippm-twamp-yang-13 (work
in progress), July 2018.
[I-D.ietf-mpls-base-yang]
Saad, T., Raza, K., Gandhi, R., Liu, X., and V. Beeram, "A
YANG Data Model for MPLS Base", draft-ietf-mpls-base-
yang-14 (work in progress), March 2020.
[I-D.ietf-opsawg-l3sm-l3nm]
Barguil, S., Dios, O., Boucadair, M., Munoz, L., and A.
Aguado, "A Layer 3 VPN Network YANG Model", draft-ietf-
opsawg-l3sm-l3nm-03 (work in progress), April 2020.
[I-D.ietf-pim-igmp-mld-snooping-yang]
Zhao, H., Liu, X., Liu, Y., Sivakumar, M., and A. Peter,
"A Yang Data Model for IGMP and MLD Snooping", draft-ietf-
pim-igmp-mld-snooping-yang-12 (work in progress), May
2020.
[I-D.ietf-pim-yang]
Liu, X., McAllister, P., Peter, A., Sivakumar, M., Liu,
Y., and f. hu, "A YANG Data Model for Protocol Independent
Multicast (PIM)", draft-ietf-pim-yang-17 (work in
progress), May 2018.
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[I-D.ietf-rtgwg-device-model]
Lindem, A., Berger, L., Bogdanovic, D., and C. Hopps,
"Network Device YANG Logical Organization", draft-ietf-
rtgwg-device-model-02 (work in progress), March 2017.
[I-D.ietf-rtgwg-policy-model]
Qu, Y., Tantsura, J., Lindem, A., and X. Liu, "A YANG Data
Model for Routing Policy Management", draft-ietf-rtgwg-
policy-model-15 (work in progress), June 2020.
[I-D.ietf-rtgwg-qos-model]
Choudhary, A., Jethanandani, M., Strahle, N., Aries, E.,
and I. Chen, "YANG Model for QoS", draft-ietf-rtgwg-qos-
model-01 (work in progress), April 2020.
[I-D.ietf-spring-sr-yang]
Litkowski, S., Qu, Y., Lindem, A., Sarkar, P., and J.
Tantsura, "YANG Data Model for Segment Routing", draft-
ietf-spring-sr-yang-15 (work in progress), January 2020.
[I-D.ietf-supa-generic-policy-data-model]
Halpern, J. and J. Strassner, "Generic Policy Data Model
for Simplified Use of Policy Abstractions (SUPA)", draft-
ietf-supa-generic-policy-data-model-04 (work in progress),
June 2017.
[I-D.ietf-teas-actn-pm-telemetry-autonomics]
Lee, Y., Dhody, D., Karunanithi, S., Vilata, R., King, D.,
and D. Ceccarelli, "YANG models for VN/TE Performance
Monitoring Telemetry and Scaling Intent Autonomics",
draft-ietf-teas-actn-pm-telemetry-autonomics-02 (work in
progress), March 2020.
[I-D.ietf-teas-actn-vn-yang]
Lee, Y., Dhody, D., Ceccarelli, D., Bryskin, I., and B.
Yoon, "A Yang Data Model for VN Operation", draft-ietf-
teas-actn-vn-yang-08 (work in progress), March 2020.
[I-D.ietf-teas-yang-path-computation]
Busi, I., Belotti, S., Lopezalvarez, V., Sharma, A., and
Y. Shi, "Yang model for requesting Path Computation",
draft-ietf-teas-yang-path-computation-09 (work in
progress), June 2020.
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[I-D.ietf-teas-yang-rsvp-te]
Beeram, V., Saad, T., Gandhi, R., Liu, X., Bryskin, I.,
and H. Shah, "A YANG Data Model for RSVP-TE Protocol",
draft-ietf-teas-yang-rsvp-te-08 (work in progress), March
2020.
[I-D.ietf-teas-yang-te]
Saad, T., Gandhi, R., Liu, X., Beeram, V., and I. Bryskin,
"A YANG Data Model for Traffic Engineering Tunnels and
Interfaces", draft-ietf-teas-yang-te-23 (work in
progress), March 2020.
[I-D.ietf-teas-yang-te-topo]
Liu, X., Bryskin, I., Beeram, V., Saad, T., Shah, H., and
O. Dios, "YANG Data Model for Traffic Engineering (TE)
Topologies", draft-ietf-teas-yang-te-topo-22 (work in
progress), June 2019.
[I-D.ietf-trill-yang-oam]
Kumar, D., Senevirathne, T., Finn, N., Salam, S., Xia, L.,
and H. Weiguo, "YANG Data Model for TRILL Operations,
Administration, and Maintenance (OAM)", draft-ietf-trill-
yang-oam-05 (work in progress), March 2017.
[I-D.ogondio-opsawg-uni-topology]
Dios, O., Barguil, S., WU, Q., and M. Boucadair, "A YANG
Model for User-Network Interface (UNI) Topologies", draft-
ogondio-opsawg-uni-topology-01 (work in progress), April
2020.
[I-D.www-bess-yang-vpn-service-pm]
WU, Q., Boucadair, M., Dios, O., Wen, B., Liu, C., and H.
Xu, "A YANG Model for Network and VPN Service Performance
Monitoring", draft-www-bess-yang-vpn-service-pm-06 (work
in progress), April 2020.
[I-D.wwx-netmod-event-yang]
Birkholz, H., WU, Q., Bryskin, I., Liu, X., and B. Claise,
"A YANG Data model for ECA Policy Management", draft-wwx-
netmod-event-yang-07 (work in progress), May 2020.
[RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February
2006, <https://www.rfc-editor.org/info/rfc4364>.
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[RFC4664] Andersson, L., Ed. and E. Rosen, Ed., "Framework for Layer
2 Virtual Private Networks (L2VPNs)", RFC 4664,
DOI 10.17487/RFC4664, September 2006,
<https://www.rfc-editor.org/info/rfc4664>.
[RFC4761] Kompella, K., Ed. and Y. Rekhter, Ed., "Virtual Private
LAN Service (VPLS) Using BGP for Auto-Discovery and
Signaling", RFC 4761, DOI 10.17487/RFC4761, January 2007,
<https://www.rfc-editor.org/info/rfc4761>.
[RFC4762] Lasserre, M., Ed. and V. Kompella, Ed., "Virtual Private
LAN Service (VPLS) Using Label Distribution Protocol (LDP)
Signaling", RFC 4762, DOI 10.17487/RFC4762, January 2007,
<https://www.rfc-editor.org/info/rfc4762>.
[RFC5136] Chimento, P. and J. Ishac, "Defining Network Capacity",
RFC 5136, DOI 10.17487/RFC5136, February 2008,
<https://www.rfc-editor.org/info/rfc5136>.
[RFC5486] Malas, D., Ed. and D. Meyer, Ed., "Session Peering for
Multimedia Interconnect (SPEERMINT) Terminology",
RFC 5486, DOI 10.17487/RFC5486, March 2009,
<https://www.rfc-editor.org/info/rfc5486>.
[RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
<https://www.rfc-editor.org/info/rfc5880>.
[RFC6406] Malas, D., Ed. and J. Livingood, Ed., "Session PEERing for
Multimedia INTerconnect (SPEERMINT) Architecture",
RFC 6406, DOI 10.17487/RFC6406, November 2011,
<https://www.rfc-editor.org/info/rfc6406>.
[RFC7149] Boucadair, M. and C. Jacquenet, "Software-Defined
Networking: A Perspective from within a Service Provider
Environment", RFC 7149, DOI 10.17487/RFC7149, March 2014,
<https://www.rfc-editor.org/info/rfc7149>.
[RFC7276] Mizrahi, T., Sprecher, N., Bellagamba, E., and Y.
Weingarten, "An Overview of Operations, Administration,
and Maintenance (OAM) Tools", RFC 7276,
DOI 10.17487/RFC7276, June 2014,
<https://www.rfc-editor.org/info/rfc7276>.
[RFC7297] Boucadair, M., Jacquenet, C., and N. Wang, "IP
Connectivity Provisioning Profile (CPP)", RFC 7297,
DOI 10.17487/RFC7297, July 2014,
<https://www.rfc-editor.org/info/rfc7297>.
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[RFC7455] Senevirathne, T., Finn, N., Salam, S., Kumar, D., Eastlake
3rd, D., Aldrin, S., and Y. Li, "Transparent
Interconnection of Lots of Links (TRILL): Fault
Management", RFC 7455, DOI 10.17487/RFC7455, March 2015,
<https://www.rfc-editor.org/info/rfc7455>.
[RFC7679] Almes, G., Kalidindi, S., Zekauskas, M., and A. Morton,
Ed., "A One-Way Delay Metric for IP Performance Metrics
(IPPM)", STD 81, RFC 7679, DOI 10.17487/RFC7679, January
2016, <https://www.rfc-editor.org/info/rfc7679>.
[RFC7680] Almes, G., Kalidindi, S., Zekauskas, M., and A. Morton,
Ed., "A One-Way Loss Metric for IP Performance Metrics
(IPPM)", STD 82, RFC 7680, DOI 10.17487/RFC7680, January
2016, <https://www.rfc-editor.org/info/rfc7680>.
[RFC8077] Martini, L., Ed. and G. Heron, Ed., "Pseudowire Setup and
Maintenance Using the Label Distribution Protocol (LDP)",
STD 84, RFC 8077, DOI 10.17487/RFC8077, February 2017,
<https://www.rfc-editor.org/info/rfc8077>.
[RFC8194] Schoenwaelder, J. and V. Bajpai, "A YANG Data Model for
LMAP Measurement Agents", RFC 8194, DOI 10.17487/RFC8194,
August 2017, <https://www.rfc-editor.org/info/rfc8194>.
[RFC8199] Bogdanovic, D., Claise, B., and C. Moberg, "YANG Module
Classification", RFC 8199, DOI 10.17487/RFC8199, July
2017, <https://www.rfc-editor.org/info/rfc8199>.
[RFC8299] Wu, Q., Ed., Litkowski, S., Tomotaki, L., and K. Ogaki,
"YANG Data Model for L3VPN Service Delivery", RFC 8299,
DOI 10.17487/RFC8299, January 2018,
<https://www.rfc-editor.org/info/rfc8299>.
[RFC8309] Wu, Q., Liu, W., and A. Farrel, "Service Models
Explained", RFC 8309, DOI 10.17487/RFC8309, January 2018,
<https://www.rfc-editor.org/info/rfc8309>.
[RFC8328] Liu, W., Xie, C., Strassner, J., Karagiannis, G., Klyus,
M., Bi, J., Cheng, Y., and D. Zhang, "Policy-Based
Management Framework for the Simplified Use of Policy
Abstractions (SUPA)", RFC 8328, DOI 10.17487/RFC8328,
March 2018, <https://www.rfc-editor.org/info/rfc8328>.
[RFC8345] Clemm, A., Medved, J., Varga, R., Bahadur, N.,
Ananthakrishnan, H., and X. Liu, "A YANG Data Model for
Network Topologies", RFC 8345, DOI 10.17487/RFC8345, March
2018, <https://www.rfc-editor.org/info/rfc8345>.
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[RFC8346] Clemm, A., Medved, J., Varga, R., Liu, X.,
Ananthakrishnan, H., and N. Bahadur, "A YANG Data Model
for Layer 3 Topologies", RFC 8346, DOI 10.17487/RFC8346,
March 2018, <https://www.rfc-editor.org/info/rfc8346>.
[RFC8349] Lhotka, L., Lindem, A., and Y. Qu, "A YANG Data Model for
Routing Management (NMDA Version)", RFC 8349,
DOI 10.17487/RFC8349, March 2018,
<https://www.rfc-editor.org/info/rfc8349>.
[RFC8466] Wen, B., Fioccola, G., Ed., Xie, C., and L. Jalil, "A YANG
Data Model for Layer 2 Virtual Private Network (L2VPN)
Service Delivery", RFC 8466, DOI 10.17487/RFC8466, October
2018, <https://www.rfc-editor.org/info/rfc8466>.
[RFC8512] Boucadair, M., Ed., Sivakumar, S., Jacquenet, C.,
Vinapamula, S., and Q. Wu, "A YANG Module for Network
Address Translation (NAT) and Network Prefix Translation
(NPT)", RFC 8512, DOI 10.17487/RFC8512, January 2019,
<https://www.rfc-editor.org/info/rfc8512>.
[RFC8513] Boucadair, M., Jacquenet, C., and S. Sivakumar, "A YANG
Data Model for Dual-Stack Lite (DS-Lite)", RFC 8513,
DOI 10.17487/RFC8513, January 2019,
<https://www.rfc-editor.org/info/rfc8513>.
[RFC8519] Jethanandani, M., Agarwal, S., Huang, L., and D. Blair,
"YANG Data Model for Network Access Control Lists (ACLs)",
RFC 8519, DOI 10.17487/RFC8519, March 2019,
<https://www.rfc-editor.org/info/rfc8519>.
[RFC8528] Bjorklund, M. and L. Lhotka, "YANG Schema Mount",
RFC 8528, DOI 10.17487/RFC8528, March 2019,
<https://www.rfc-editor.org/info/rfc8528>.
[RFC8529] Berger, L., Hopps, C., Lindem, A., Bogdanovic, D., and X.
Liu, "YANG Data Model for Network Instances", RFC 8529,
DOI 10.17487/RFC8529, March 2019,
<https://www.rfc-editor.org/info/rfc8529>.
[RFC8530] Berger, L., Hopps, C., Lindem, A., Bogdanovic, D., and X.
Liu, "YANG Model for Logical Network Elements", RFC 8530,
DOI 10.17487/RFC8530, March 2019,
<https://www.rfc-editor.org/info/rfc8530>.
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[RFC8531] Kumar, D., Wu, Q., and Z. Wang, "Generic YANG Data Model
for Connection-Oriented Operations, Administration, and
Maintenance (OAM) Protocols", RFC 8531,
DOI 10.17487/RFC8531, April 2019,
<https://www.rfc-editor.org/info/rfc8531>.
[RFC8532] Kumar, D., Wang, Z., Wu, Q., Ed., Rahman, R., and S.
Raghavan, "Generic YANG Data Model for the Management of
Operations, Administration, and Maintenance (OAM)
Protocols That Use Connectionless Communications",
RFC 8532, DOI 10.17487/RFC8532, April 2019,
<https://www.rfc-editor.org/info/rfc8532>.
[RFC8533] Kumar, D., Wang, M., Wu, Q., Ed., Rahman, R., and S.
Raghavan, "A YANG Data Model for Retrieval Methods for the
Management of Operations, Administration, and Maintenance
(OAM) Protocols That Use Connectionless Communications",
RFC 8533, DOI 10.17487/RFC8533, April 2019,
<https://www.rfc-editor.org/info/rfc8533>.
[RFC8632] Vallin, S. and M. Bjorklund, "A YANG Data Model for Alarm
Management", RFC 8632, DOI 10.17487/RFC8632, September
2019, <https://www.rfc-editor.org/info/rfc8632>.
[RFC8652] Liu, X., Guo, F., Sivakumar, M., McAllister, P., and A.
Peter, "A YANG Data Model for the Internet Group
Management Protocol (IGMP) and Multicast Listener
Discovery (MLD)", RFC 8652, DOI 10.17487/RFC8652, November
2019, <https://www.rfc-editor.org/info/rfc8652>.
[RFC8675] Boucadair, M., Farrer, I., and R. Asati, "A YANG Data
Model for Tunnel Interface Types", RFC 8675,
DOI 10.17487/RFC8675, November 2019,
<https://www.rfc-editor.org/info/rfc8675>.
[RFC8676] Farrer, I., Ed. and M. Boucadair, Ed., "YANG Modules for
IPv4-in-IPv6 Address plus Port (A+P) Softwires", RFC 8676,
DOI 10.17487/RFC8676, November 2019,
<https://www.rfc-editor.org/info/rfc8676>.
[RFC8783] Boucadair, M., Ed. and T. Reddy.K, Ed., "Distributed
Denial-of-Service Open Threat Signaling (DOTS) Data
Channel Specification", RFC 8783, DOI 10.17487/RFC8783,
May 2020, <https://www.rfc-editor.org/info/rfc8783>.
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Appendix A. Layered YANG Modules Examples Overview
This appendix lists a set of data models that can be used for the
delivery of connectivity services. These models can be classified as
Service, Network, or Device Models.
It is not the intent of this appendix to provide an inventory of
tools and mechanisms used in specific network and service management
domains; such inventory can be found in documents such as [RFC7276].
A.1. Service Models: Definition and Samples
As described in [RFC8309], the service is "some form of connectivity
between customer sites and the Internet and/or between customer sites
across the Network Operator's network and across the Internet". More
concretely, an IP connectivity service can be defined as the IP
transfer capability characterized by a (Source Nets, Destination
Nets, Guarantees, Scope) tuple where "Source Nets" is a group of
unicast IP addresses, "Destination Nets" is a group of IP unicast
and/or multicast addresses, and "Guarantees" reflects the guarantees
(expressed in terms of QoS, performance, and availability, for
example) to properly forward traffic to the said "Destination"
[RFC7297].
For example:
o The L3SM model [RFC8299] defines the L3VPN service ordered by a
customer from a Network Operator.
o The L2SM model [RFC8466] defines the L2VPN service ordered by a
customer from a Network Operator.
o The Virtual Network (VN) model [I-D.ietf-teas-actn-vn-yang]
provides a YANG data model applicable to any mode of VN operation.
L2SM and L3SM are customer service models as per [RFC8309].
A.2. Network Models: Samples
L2NM [I-D.barguil-opsawg-l2sm-l2nm] and L3NM
[I-D.ietf-opsawg-l3sm-l3nm] are examples of YANG Network Models.
Figure 9 depicts a set of additional Network Models such as topology
and tunnel models:
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+-------------------------------+-------------------------------+
| Topology YANG modules | Tunnel YANG modules |
+-------------------------------+-------------------------------+
| +------------+ | |
| |Network Topo| | +------+ +-----------+ |
| | Model | | |Other | | TE Tunnel | |
| +----+-------+ | |Tunnel| +----+------+ |
| | +--------+ | +------+ | |
| +---+Svc Topo| | +----------+---------+ |
| | +--------+ | | | | |
| | +--------+ |+----+---+ +----+---+ +---+---+|
| +---+L2 Topo | ||MPLS-TE | |RSVP-TE | | SR-TE ||
| | +--------+ || Tunnel | | Tunnel | |Tunnel ||
| | +--------+ |+--------+ +--------+ +-------+|
| +---+TE Topo | | |
| | +--------+ | |
| | +--------+ | |
| +---+L3 Topo | | |
| +--------+ | |
+-------------------------------+-------------------------------+
Legend:
Topo: Topology
Svc: Service
Figure 9: Sample Resource Facing Network Models
Examples of topology YANG modules are listed below:
o Network Topology Models: [RFC8345] defines a base model for
network topology and inventories. Network topology data include
link resource, node resource, and terminate-point resources.
o TE Topology Models: [I-D.ietf-teas-yang-te-topo] defines a data
model for representing and manipulating TE topologies.
This module is extended from network topology model defined in
[RFC8345] with TE topologies specifics. This model contains
technology-agnostic TE Topology building blocks that can be
augmented and used by other technology-specific TE topology
models.
o Layer 3 Topology Models:
[RFC8346] defines a data model for representing and manipulating
Layer 3 topologies. This model is extended from the network
topology model defined in [RFC8345] with Layer 3 topologies
specifics.
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o Layer 2 Topology Models:
[I-D.ietf-i2rs-yang-l2-network-topology] defines a data model for
representing and manipulating Layer 2 topologies. This model is
extended from the network topology model defined in [RFC8345] with
Layer 2 topologies specifics.
Examples of tunnel YANG modules are provided below:
o Tunnel identities to ease manipulating extensions to specific
tunnels [RFC8675].
o TE Tunnel Model:
[I-D.ietf-teas-yang-te] defines a YANG module for the
configuration and management of TE interfaces, tunnels, and LSPs.
o Segment Routing (SR) Traffic Engineering (TE) Tunnel Model:
[I-D.ietf-teas-yang-te] augments the TE generic and MPLS-TE
model(s) and defines a YANG module for SR-TE specific data.
o MPLS-TE Model:
[I-D.ietf-teas-yang-te] augments the TE generic and MPLS-TE
model(s) and defines a YANG module for MPLS-TE configurations,
state, RPC and notifications.
o RSVP-TE MPLS Model:
[I-D.ietf-teas-yang-rsvp-te] augments the RSVP-TE generic module
with parameters to configure and manage signaling of MPLS RSVP-TE
LSPs.
Other sample Network Models are listed hereafter:
o Path Computation API Model:
[I-D.ietf-teas-yang-path-computation] YANG module for a stateless
RPC which complements the stateful solution defined in
[I-D.ietf-teas-yang-te].
o OAM Models (including Fault Management (FM) and Performance
Monitoring):
[RFC8532] defines a base YANG module for the management of OAM
protocols that use Connectionless Communications. [RFC8533]
defines a retrieval method YANG module for connectionless OAM
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protocols. [RFC8531] defines a base YANG module for connection
oriented OAM protocols. These three models are intended to
provide consistent reporting, configuration, and representation
for connection-less OAM and Connection oriented OAM separately.
Alarm monitoring is a fundamental part of monitoring the network.
Raw alarms from devices do not always tell the status of the
network services or necessarily point to the root cause.
[RFC8632] defines a YANG module for alarm management.
o Generic Policy Model:
The Simplified Use of Policy Abstractions (SUPA) policy-based
management framework [RFC8328] defines base YANG modules
[I-D.ietf-supa-generic-policy-data-model] to encode policy. These
models point to other device-, technology-, and service-specific
YANG modules. Policy rules within an operator's environment can
be used to express high-level, possibly network-wide, policies to
a network management function (within a controller, an
orchestrator, or a network element). The network management
function can then control the configuration and/or monitoring of
network elements and services. This document describes the SUPA
basic framework, its elements, and interfaces.
A.3. Device Models: Samples
Network Element models (Figure 10) are used to describe how a service
can be implemented by activating and tweaking a set of functions
(enabled in one or multiple devices, or hosted in cloud
infrastructures) that are involved in the service delivery.
Figure 10 uses IETF-defined models as an example.
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+------------------------+
+-+ Device Model |
| +------------------------+
| +------------------------+
+---------------+ | | Logical Network |
| | +-+ Element Model |
| Architecture | | +------------------------+
| | | +------------------------+
+-------+-------+ +-+ Network Instance Model |
| | +------------------------+
| | +------------------------+
| +-+ Routing Type Model |
| +------------------------+
+-------+----------+----+------+------------+-----------+------+
| | | | | | |
+-+-+ +---+---+ +----+----+ +--+--+ +----+----+ +--+--+ |
|ACL| |Routing| |Transport| | OAM | |Multicast| | PM | Others
+---+ +-+-----+ +----+----+ +--+--+ +-----+---+ +--+--+
| +-------+ | +------+ | +--------+ | +-----+ | +-----+
+-+Core | +-+ MPLS | +-+ BFD | +-+IGMP | +-+TWAMP|
| |Routing| | | Base | | +--------+ | |/MLD | | +-----+
| +-------+ | +------+ | +--------+ | +-----+ | +-----+
| +-------+ | +------+ +-+LSP Ping| | +-----+ +-+OWAMP|
+-+ BGP | +-+ MPLS | | +--------+ +-+ PIM | | +-----+
| +-------+ | | LDP | | +--------+ | +-----+ | +-----+
| +-------+ | +------+ +-+MPLS-TP | | +-----+ +-+LMAP |
+-+ ISIS | | +------+ +--------+ +-+ MVPN| +-----+
| +-------+ +-+ MPLS | +-----+
| +-------+ |Static|
+-+ OSPF | +------+
| +-------+
| +-------+
+-+ RIP |
| +-------+
| +-------+
+-+ VRRP |
| +-------+
| +-------+
+-+SR/SRv6|
| +-------+
| +-------+
+-+ISIS-SR|
| +-------+
| +-------+
+-+OSPF-SR|
+-------+
Figure 10: Network Element Modules Overview
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A.3.1. Model Composition
o Device Model
[I-D.ietf-rtgwg-device-model] presents an approach for organizing
YANG modules in a comprehensive logical structure that may be used
to configure and operate network devices. The structure is itself
represented as an example YANG module, with all of the related
component models logically organized in a way that is
operationally intuitive, but this model is not expected to be
implemented.
o Logical Network Element Model
[RFC8530] defines a logical network element module which can be
used to manage the logical resource partitioning that may be
present on a network device. Examples of common industry terms
for logical resource partitioning are Logical Systems or Logical
Routers.
o Network Instance Model
[RFC8529] defines a network instance module. This module can be
used to manage the virtual resource partitioning that may be
present on a network device. Examples of common industry terms
for virtual resource partitioning are VRF instances and Virtual
Switch Instances (VSIs).
A.3.1.1. Schema Mount
Modularity and extensibility were among the leading design principles
of the YANG data modeling language. As a result, the same YANG
module can be combined with various sets of other modules and thus
form a data model that is tailored to meet the requirements of a
specific use case. [RFC8528] defines a mechanism, denoted schema
mount, that allows for mounting one data model consisting of any
number of YANG modules at a specified location of another (parent)
schema.
That capability does not cover design time.
A.3.2. Device Models: Samples
The following provides an overview of some Device Models that can be
used within a network. This list is not comprehensive.
BGP: [I-D.ietf-idr-bgp-model] defines a YANG module for
configuring and managing BGP, including protocol, policy,
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and operational aspects based on data center, carrier, and
content provider operational requirements.
MPLS: [I-D.ietf-mpls-base-yang] defines a base model for MPLS
which serves as a base framework for configuring and
managing an MPLS switching subsystem. It is expected that
other MPLS technology YANG modules (e.g., MPLS LSP Static,
LDP, or RSVP-TE models) will augment the MPLS base YANG
module.
QoS: [I-D.ietf-rtgwg-qos-model] describes a YANG module of
Differentiated Services for configuration and operations.
ACL: Access Control List (ACL) is one of the basic elements
used to configure device forwarding behavior. It is used
in many networking technologies such as Policy Based
Routing, Firewalls, etc. [RFC8519] describes a data model
of ACL basic building blocks.
NAT: For the sake of network automation and the need for
programming Network Address Translation (NAT) function in
particular, a data model for configuring and managing the
NAT is essential.
[RFC8512] defines a YANG module for the NAT function
covering a variety of NAT flavors such as Network Address
Translation from IPv4 to IPv4 (NAT44), Network Address and
Protocol Translation from IPv6 Clients to IPv4 Servers
(NAT64), customer-side translator (CLAT), Stateless IP/
ICMP Translation (SIIT), Explicit Address Mappings (EAM)
for SIIT, IPv6-to-IPv6 Network Prefix Translation (NPTv6),
and Destination NAT.
[RFC8513] specifies a DS-Lite YANG module.
Stateless Address Sharing: [RFC8676] specifies a YANG module for A+P
address sharing, including Lightweight 4over6, Mapping of
Address and Port with Encapsulation (MAP-E), and Mapping
of Address and Port using Translation (MAP-T) softwire
mechanisms.
Multicast: [I-D.ietf-pim-yang] defines a YANG module that can be used
to configure and manage Protocol Independent Multicast
(PIM) devices.
[RFC8652] defines a YANG module that can be used to
configure and manage Internet Group Management Protocol
(IGMP) and Multicast Listener Discovery (MLD) devices.
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[I-D.ietf-pim-igmp-mld-snooping-yang] defines a YANG
module that can be used to configure and manage Internet
Group Management Protocol (IGMP) and Multicast Listener
Discovery (MLD) Snooping devices.
[I-D.ietf-bess-mvpn-yang] defines a YANG data model to
configure and manage Multicast in MPLS/BGP IP VPNs
(MVPNs).
EVPN: [I-D.ietf-bess-evpn-yang] defines a YANG module for
Ethernet VPN services. The model is agnostic of the
underlay. It applies to MPLS as well as to VxLAN
encapsulation. The module is also agnostic to the
services, including E-LAN, E-LINE, and E-TREE services.
L3VPN: [I-D.ietf-bess-l3vpn-yang] defines a YANG module that can
be used to configure and manage BGP L3VPNs [RFC4364]. It
contains VRF specific parameters as well as BGP specific
parameters applicable for L3VPNs.
L2VPN: [I-D.ietf-bess-l2vpn-yang] defines a YANG module for MPLS
based Layer 2 VPN services (L2VPN) [RFC4664] and includes
switching between the local attachment circuits. The
L2VPN model covers point-to-point VPWS and Multipoint VPLS
services. These services use signaling of Pseudowires
across MPLS networks using LDP [RFC8077][RFC4762] or BGP
[RFC4761].
Routing Policy: [I-D.ietf-rtgwg-policy-model] defines a YANG module
for configuring and managing routing policies based on
operational practice. The module provides a generic
policy framework which can be augmented with protocol-
specific policy configuration.
BFD: Bidirectional Forwarding Detection (BFD) [RFC5880] is a
network protocol which is used for liveness detection of
arbitrary paths between systems. [I-D.ietf-bfd-yang]
defines a YANG module that can be used to configure and
manage BFD.
SR/SRv6: [I-D.ietf-spring-sr-yang] a YANG module for segment
routing configuration and operation.
Core Routing: [RFC8349] defines the core routing data model, which
is intended as a basis for future data model development
covering more-sophisticated routing systems. It is
expected that other Routing technology YANG modules (e.g.,
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VRRP, RIP, ISIS, OSPF models) will augment the Core
Routing base YANG module.
PM: [I-D.ietf-ippm-twamp-yang] defines a data model for client
and server implementations of the Two-Way Active
Measurement Protocol (TWAMP).
[I-D.ietf-ippm-stamp-yang] defines the data model for
implementations of Session-Sender and Session-Reflector
for Simple Two-way Active Measurement Protocol (STAMP)
mode using YANG.
[RFC8194] defines a data model for Large-Scale Measurement
Platforms (LMAPs).
Authors' Addresses
Qin Wu (editor)
Huawei
101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012
China
Email: bill.wu@huawei.com
Mohamed Boucadair (editor)
Orange
Rennes 35000
France
Email: mohamed.boucadair@orange.com
Diego R. Lopez
Telefonica I+D
Spain
Email: diego.r.lopez@telefonica.com
Chongfeng Xie
China Telecom
Beijing
China
Email: xiechf@chinatelecom.cn
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Liang Geng
China Mobile
Email: gengliang@chinamobile.com
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