A Framework for Automating Service and Network Management with YANG
draft-ietf-opsawg-model-automation-framework-02
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft that was ultimately published as RFC 8969.
|
|
|---|---|---|---|
| Authors | Qin Wu , Mohamed Boucadair , Diego Lopez , Chongfeng Xie , Liang Geng | ||
| Last updated | 2020-03-17 | ||
| Replaces | draft-wu-model-driven-management-virtualization | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Formats | |||
| Reviews |
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| Additional resources | Mailing list discussion | ||
| Stream | WG state | WG Document | |
| Document shepherd | (None) | ||
| IESG | IESG state | Became RFC 8969 (Informational) | |
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draft-ietf-opsawg-model-automation-framework-02
OPSAWG Q. Wu, Ed.
Internet-Draft Huawei
Intended status: Informational M. Boucadair, Ed.
Expires: September 18, 2020 Orange
D. Lopez
Telefonica I+D
C. Xie
China Telecom
L. Geng
China Mobile
March 17, 2020
A Framework for Automating Service and Network Management with YANG
draft-ietf-opsawg-model-automation-framework-02
Abstract
Data models for service and network management provides a
programmatic approach for representing (virtual) services or networks
and deriving (1) configuration information that will be communicated
to network and service components that are used to build and deliver
the service and (2) state information that will be monitored and
tracked. Indeed, data models can be used during various phases of
the service and network management life cycle, such as service
instantiation, service provisioning, optimization, monitoring,
diagnostic, and assurance. Also, data models are instrumental in the
automation of network management. They also provide closed-loop
control for the sake of 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 provider
perspective irrespective of the origin of a data module; it can thus
accommodate even modules that are developed outside the IETF.
The document aims in particular to exemplify an approach that
specifies the journey from technology-agnostic services to
technology-specific actions.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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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 September 18, 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
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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Architectural Concepts & Goals . . . . . . . . . . . . . . . 5
3.1. Data Models: Layering and Representation . . . . . . . . 5
3.2. Automation of Service Delivery Procedures . . . . . . . . 8
3.3. Service Fullfillment Automation . . . . . . . . . . . . . 9
3.4. YANG Modules Integration . . . . . . . . . . . . . . . . 9
4. Functional Bocks and Interactions . . . . . . . . . . . . . . 10
4.1. Service Lifecycle Management Procedure . . . . . . . . . 11
4.1.1. Service Exposure . . . . . . . . . . . . . . . . . . 11
4.1.2. Service Creation/Modification . . . . . . . . . . . . 12
4.1.3. Service Optimization . . . . . . . . . . . . . . . . 12
4.1.4. Service Diagnosis . . . . . . . . . . . . . . . . . . 13
4.1.5. Service Decommission . . . . . . . . . . . . . . . . 13
4.2. Service Fullfillment Management Procedure . . . . . . . . 13
4.2.1. Intended Configuration Provision . . . . . . . . . . 13
4.2.2. Configuration Validation . . . . . . . . . . . . . . 14
4.2.3. Performance Monitoring/Model-driven Telemetry . . . . 14
4.2.4. Fault Diagnostic . . . . . . . . . . . . . . . . . . 15
4.3. Multi-layer/Multi-domain Service Mapping . . . . . . . . 15
4.4. Service Decomposing . . . . . . . . . . . . . . . . . . . 15
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5. YANG Data Model Integration Examples . . . . . . . . . . . . 16
5.1. L3VPN Service Delivery . . . . . . . . . . . . . . . . . 16
5.2. VN Lifecycle Management . . . . . . . . . . . . . . . . . 17
5.3. Event-based Telemetry in the Device Self Management . . . 18
6. Security Considerations . . . . . . . . . . . . . . . . . . . 19
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 19
9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 20
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 20
10.1. Normative References . . . . . . . . . . . . . . . . . . 20
10.2. Informative References . . . . . . . . . . . . . . . . . 21
Appendix A. Layered YANG Modules Examples Overview . . . . . . . 27
A.1. Service Models: Definition and Samples . . . . . . . . . 27
A.2. Network Models: Samples . . . . . . . . . . . . . . . . . 28
A.3. Device Models: Samples . . . . . . . . . . . . . . . . . 30
A.3.1. Model Composition . . . . . . . . . . . . . . . . . . 31
A.3.2. Device Models: Samples . . . . . . . . . . . . . . . 32
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 35
1. Introduction
The service management system usually comprises service activation/
provision and service operation. Current service delivery
procedures, from the processing of customer's requirements and order
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, etc.). In addition, many of these applications
have been developed in-house over the years and operating in a silo
mode:
o The lack of standard data input/output (i.e., data model) also
raises many challenges in system integration and often results in
manual configuration tasks.
o Secondly, many current service fulfillment system might have a
limited visibility on the network state and therefore have slow
response to the network changes.
Software Defined Networking (SDN) becomes crucial to address these
challenges. SDN techniques [RFC7149] are meant to automate the
overall service delivery procedures and typically rely upon
(standard) data models that 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 (contractually) defined (and possibly negotiated) with
the customer. [RFC7149] provides a first tentative to rationalize
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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
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 perspective.
Models are key for each of these 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 on the
top or abstracting common construct from various network technologies
on 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 even provide a service is something that is
not currently documented either within the IETF or other SDOs (e.g.,
MEF).
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 provider perspective
irrespective of the origin of a data module; it can accommodate even
modules that are developed outside the IETF.
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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.
2. 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
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. It can be used by a
network operator to allocate the resource (e.g., tunnel resource,
topology resource) for the service or schedule the resource to
meet the service requirements defined in a Service Model.
Device Model: Refers to the Network Element YANG data module
described in [RFC8199]. Device Model is also used to refer to
model a function embedded in a device (e.g., NAT [RFC8512], ACL
[RFC8519]).
3. Architectural Concepts & Goals
3.1. Data Models: Layering and Representation
As described in [RFC8199], layering of modules allows for better
reusability of lower-layer modules by higher-level modules while
limiting duplication of features across layers.
The 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.
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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., L3VPN), which can be mapped to
network technology-specific modules at lower layers (e.g., tunnel,
routing, 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 the communication scope (pipe, hose,
funnel, ...), the directionality, the traffic performance guarantees
(one-way delay (OWD), one-way loss, ...), etc.
Figure 1 depicts the example of a VoIP service provider that relies
in the connectivity services offered by a network provider. 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
`-. Provider ,-' `-. ,-' (3)
`--'--'--' `--'--'--'
**** (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
* inter-SP connectivity (1)
- Pipe scope from the local to the remote VoIP gateway
- Full guarantees class
* Customer to SP connectivity (2)
- Hose/Funnel scope connecting the local VoIP gateway
to the customer access points
- Full guarantees class
* SP to any destination connectivity (3)
- Hose/Funnel scope from the local VoIP gateway to the
Internet gateway
- Delay guarantees class
Flow Identification
* Destination IP address (SBC, SBE, DBE)
* DSCP marking
Traffic Isolation
* VPN
Routing & Forwarding
* Routing rule to exclude 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 and
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.
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+-----------------------------------------------------------------+
| +-----------------------+ |
| | Orchestrator | Hierarchy Abstraction |
| |+---------------------+| |
| || Service Modeling || Service Model |
| |+---------------------+| (Customer Oriented) |
| | | Scope: "1:1" Pipe model |
| | | Bidirectional |
| |+---------------------+| +-+ BW:100M,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|
| +-----------------------+ Proto Type/BW/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 an 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 modules are used to feed a
decision-making intelligence to adequately accommodate customer's
needs.
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Such modules may also 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 DDoS
attacks [I-D.ietf-dots-signal-channel][I-D.ietf-dots-data-channel].
Network Models can be derived from Service Models and used to
provision, monitor, instantiate the service, and provide lifecycle
management of network resources (e.g., expose network resources to
customers or operators to provide service fulfillment and assurance
and allow customers or 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, Device Models derived from Service Models or
Network Models can be used to provision each involved network
function/device with the proper configuration information, and
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 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
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
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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., AS 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 led 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
Fullfillment 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
span across multiple administrative domain or multiple layers while
technology specific service lifecycle management is technology domain
specific or layer specific service lifecycle management.
4.1.1. Service Exposure
A service in the context of this document (sometimes called a Network
Service) is some form of connectivity between customer sites and the
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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 L3SM service model 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 the service
model.
Upon receiving the service request, the service orchestrator/
management system should first verify whether the service
requirements in the service request can be met (i.e., whether there
is sufficient resource that can be allocated).
In successful case, 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 underlying network
infrastructure to adapt to new customer's needs and service
requirements. This service modification can be issued in 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 change, incident mitigation, or
new service requirements. One typical example is once the tunnel or
the 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
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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 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 recommendation (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 provide consistent
configuration, reporting, and presentation for the OAM mechanisms
used to manage the network.
4.1.5. Service Decommission
Service decommission allow the customer to stop the service and
remove the service from active status and release the network
resource that is allocated to the service. Customer can also use the
service model to withdraw the registration to a service.
4.2. Service Fullfillment Management Procedure
4.2.1. Intended Configuration Provision
Intended configuration at the device level is derived from network
model at the network level or service model at the service level and
represents the configuration that the system attempts to apply. Take
L3SM service model as an example, to deliver a L3VPN service, we need
to map L3VPN service view defined in Service model into detailed
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intended configuration view defined by specific configuration models
for network elements, configuration information includes:
o VRF definition, including VPN Policy expression
o Physical Interface
o IP layer (IPv4, IPv6)
o QoS features such as classification, profiles, etc.
o Routing protocols: support of configuration of all protocols
listed in the document, as well as routing policies associated
with those protocols.
o Multicast Support
o Address sharing
o Security function
This specific configuration models can be used to configure Provider
Edge (PE) and Customer Edge (CE) devices within the 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 "et-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.
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
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build full topological visibility to 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 device may be
mis-configured(e.g.,device links are not consistent on 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 can be used to deal with these
challenges.
These RPC commands received in the technology dependent node can be
used to trigger technology specific OAM message exchange for fault
verification and fault isolation,e.g., 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 allow you map end to end
abstract view of the service segmented at different layer or
different administrative domain into domain specific view. One
example is to map service parameters in L3VPN service model into
configuration parameters such as RD, RT, and VRF in L3VPN network
model. Another example is to map service parameters in L3VPN service
model into TE tunnel parameter (e.g.,Tunnel ID) in TE model and VN
parameters (e.g., AP list, VN member) in TEAS VN model
[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 type or classified into a collection of related
YANG modules based on service type and feature offered and load at
the implementation time before configuration is loaded and validated.
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5. YANG Data Model Integration Examples
5.1. L3VPN Service Delivery
L3SM | ^
Service | | Notifications
Model | |
+--------------------+----------------------------+
| +-----V- -------+ |
| Orchestrator |Service Mapping| |
| +-----+---------+ |
| | |
+--------------------+----------------------------+
L3NM | ^
Network| | L3NM Notifications
Model | | L3NM Capabilities
+--------------------+----------------------------+
| Controller+--------V-----------+ |
| | Service Decomposing| |
| +-++------------++---+ |
| || || |
| || || |
+-------------++---------- ++--------------------+
|| ||
|| ||
||BGP,QoS ||
|| ||
+----------+|NI,Intf,IP |+-----------------+
+--+--+ +++---+ --+---+ +--+--+
| CE1 |------| PE1 | | PE2 | ---------+ CE2 |
+-----+ +-----+ +-----+ +-----+
Figure 5: L3VPN Service Delivery Example
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:
Site A: Network-Access A, Bandwidth=20M, for class "foo",
guaranteed-bw-percent = 10, One-Way-Delay=70 msec
Site B: Network-Access B, Bandwidth=30M, for class "foo1",
guaranteed-bw-percent = 15, One-Way-Delay=60 msec
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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 L3NM network model.
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.
[I-D.ogondio-opsawg-uni-topology] is used for representing, managing
and controlling the User Network Interface (UNI) topology.
L3NM inherits some of data elements from the L3SM. Likewise, the
L3NM 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).
5.2. VN Lifecycle Management
|
VN |
Service |
Model |
+----------------------|--------------------------+
| Orchestrator | |
| +--------V--------+ |
| | Service Mapping | |
| +-----------------+ |
+----------------------+--------------------^-----+
TE | Telemetry
Tunnel | Model
Model | |
+----------------------V--------------------+----+
| Controller |
| |
+-------------------------------------------------+
+-----+ +-----+ +-----+ +-----+
| CE1 |------| PE1 | | PE2 |---------+ CE2 |
+-----+ +-----+ +-----+ +-----+
Figure 6
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In reference to Figure 6, 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.
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 TEAS 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).
5.3. Event-based Telemetry in the Device Self Management
+----------------+
| |
| Controller |
+----------------+
|
|
ECA |
Model| ^
| |Notif
| |
+------------V-------------+-------+
|Device | Reconfig
| +-------+ +---------+ +--+---+ |
| | Event --> Event -->Event --> |
| | Source| |Condition| |Action| |
| +-------+ +---------+ +------+ |
+--------Update------trigger-------+
Figure 7: Event-based Telemetry
In reference to Figure 7, the following steps are performed to
monitor state changes of managed objects or resource in the device
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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 send updates only when the value exceeds
a certain threshold for the first time but not again until the
threshold is cleared), which constitute an event-driven policy or
network control logic in the controller.
2. The controller pushes ECA policy to the network device and
delegate network control logic to the network device.
3. The network device generates ECA script from ECA model and
execute ECA script or network control logic based on Event.
Event based notification or telemetry can be triggered if a
certain condition is satisfied (model driven telemetry operation
in Section 4.2.3).
6. Security Considerations
Security considerations specific to each of the technologies and
protocols listed in the document are discussed in the specification
documents of each of these techniques.
(Potential) 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 introduced in the document.
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, and Shunsuke Homma for the review.
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9. Contributors
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
Chongfeng Xie
China Telecom
Beijing
China
Email: xiechf.bri@chinatelecom.cn
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
[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>.
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10.2. Informative References
[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-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.
[I-D.ietf-dots-data-channel]
Boucadair, M. and T. Reddy.K, "Distributed Denial-of-
Service Open Threat Signaling (DOTS) Data Channel
Specification", draft-ietf-dots-data-channel-31 (work in
progress), July 2019.
[I-D.ietf-dots-signal-channel]
Reddy.K, T., Boucadair, M., Patil, P., Mortensen, A., and
N. Teague, "Distributed Denial-of-Service Open Threat
Signaling (DOTS) Signal Channel Specification", draft-
ietf-dots-signal-channel-41 (work in progress), January
2020.
[I-D.ietf-i2rs-yang-l2-network-topology]
Dong, J., Wei, X., WU, Q., Boucadair, M., and A. Liu, "A
YANG Data Model for Layer-2 Network Topologies", draft-
ietf-i2rs-yang-l2-network-topology-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.
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[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-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-09 (work in progress), January
2020.
[I-D.ietf-pim-yang]
Liu, X., McAllister, P., Peter, A., Sivakumar, M., Liu,
Y., and f. hu, "A YANG Data Model for Protocol Independent
Multicast (PIM)", draft-ietf-pim-yang-17 (work in
progress), May 2018.
[I-D.ietf-rtgwg-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-09 (work in progress), March 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-00 (work in progress), October 2019.
[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.
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[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-08 (work in
progress), December 2019.
[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.
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[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-00 (work in progress),
November 2019.
[RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February
2006, <https://www.rfc-editor.org/info/rfc4364>.
[RFC4664] Andersson, L., Ed. and E. Rosen, Ed., "Framework for Layer
2 Virtual Private Networks (L2VPNs)", RFC 4664,
DOI 10.17487/RFC4664, September 2006,
<https://www.rfc-editor.org/info/rfc4664>.
[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>.
[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>.
[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>.
[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>.
[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>.
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[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>.
[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>.
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[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>.
[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>.
Appendix A. Layered YANG Modules Examples Overview
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 Quality Of Service (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.
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A.2. Network Models: Samples
Figure 8 depicts a set of Network models such as topology models or
tunnel models:
| |
Topo YANG modules | Tunnel YANG modules |
------------------------------------------------|
+------------+ | |
|Network Top | | +------+ +-----------+ |
| Model | | |Other | | TE Tunnel | |
+----+-------+ | |Tunnel| +------+----+ |
| +--------+ | +------+ | |
|---+Svc Topo| | +--------+-+--------+
| +--------+ | +----+---+ +---+----+ +-+-----+
| +--------+ | |MPLS-TE | |RSVP-TE | |SR TE |
|---+L2 Topo | | | Tunnel | | Tunnel | |Tunnel |
| +--------+ | +--------+ +--------+ +-------+
| +--------+ |
|---+TE Topo | |
| +--------+ |
| +--------+ |
+---+L3 Topo | |
+--------+ |
Figure 8: Sample Resource Facing Network Models
Topology YANG module Examples:
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 L3 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 L3 topologies specifics.
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o L2 Topology Models
[I-D.ietf-i2rs-yang-l2-network-topology] defines a data model for
representing and manipulating L2 topologies. This model is
extended from the network topology model defined in [RFC8345] with
Layer 2 topologies specifics.
Tunnel YANG module Examples:
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 SR TE Tunnel Model:
[I-D.ietf-teas-yang-te] augments the TE generic and MPLS-TE
model(s) and defines a YANG module for Segment Routing (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 Network Models:
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]
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defines a retrieval method YANG module for connectionless OAM
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 9) 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 9
uses IETF-defined models as an example.
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+----------------+
--|Device Model |
| +----------------+
| +------------------+
+---------------+ | |Logical Network |
| | --| Element Mode |
| Architecture | | +------------------+
| | | +----------------------+
+-------+-------+ --|Network Instance Mode |
| | +----------------------+
| | +-------------------+
| --|Routing Type Model |
| +-------------------+
+-------+----------+----+------+------------+-----------+-------+
| | | | | | |
+-+-+ +---+---+ +--+------+ +-+-+ +-----+---+ +---+-+ |
|ACL| |Routing| |Transport| |OAM| |Multicast| | PM | Others
+---+ |-------+ +---------+ +---+ +---------+ +-----+
| +-------+ +----------+ +-------+ +-----+ +-----+
--|Core | |MPLS Basic| |BFD | |IGMP | |TWAMP|
| |Routing| +----------+ +-------+ |/MLD | +-----+
| +-------+ |MPLS LDP | |LSP Ping +-----+ |OWAMP|
--|BGP | +----------+ +-------+ |PIM | +-----+
| +-------+ |MPLS Static |MPLS-TP| +-----+ |LMAP |
--|ISIS | +----------+ +-------+ |MVPN | +-----+
| +-------+ +-----+
--|OSPF |
| +-------+
--|RIP |
| +-------+
--|VRRP |
| +-------+
--|SR/SRv6|
| +-------+
--|ISIS-SR|
| +-------+
--|OSPF-SR|
+-------+
Figure 9: Network Element Modules Overview
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
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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 Virtual Routing and
Forwarding (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,
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,
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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.
[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.
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
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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.,
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
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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.bri@chinatelecom.cn
Liang Geng
China Mobile
Email: gengliang@chinamobile.com
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