OPSAWG B. Claise
Internet-Draft Huawei
Intended status: Standards Track J. Quilbeuf
Expires: October 25, 2021 Independent
P. Lucente
NTT
P. Fasano
TIM S.p.A
T. Arumugam
Cisco Systems, Inc.
April 23, 2021
YANG Modules for Service Assurance
draft-claise-opsawg-service-assurance-yang-07
Abstract
This document proposes YANG modules for the Service Assurance for
Intent-based Networking Architecture.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on October 25, 2021.
Copyright Notice
Copyright (c) 2021 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
Claise, et al. Expires October 25, 2021 [Page 1]
Internet-Draft YANG Modules for Service Assurance April 2021
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. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
3. YANG Models Overview . . . . . . . . . . . . . . . . . . . . 3
4. Base ietf-service-assurance YANG module . . . . . . . . . . . 4
4.1. Tree View . . . . . . . . . . . . . . . . . . . . . . . . 4
4.2. Concepts . . . . . . . . . . . . . . . . . . . . . . . . 5
4.3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 6
5. Subservice Extension: ietf-service-assurance-device YANG
module . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.1. Tree View . . . . . . . . . . . . . . . . . . . . . . . . 13
5.2. Complete Tree View . . . . . . . . . . . . . . . . . . . 13
5.3. Concepts . . . . . . . . . . . . . . . . . . . . . . . . 14
5.4. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 15
6. Subservice Extension: ietf-service-assurance-interface YANG
module . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
6.1. Tree View . . . . . . . . . . . . . . . . . . . . . . . . 16
6.2. Complete Tree View . . . . . . . . . . . . . . . . . . . 17
6.3. Concepts . . . . . . . . . . . . . . . . . . . . . . . . 18
6.4. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 18
7. Vendor-specific Subservice Extension: example-service-
assurance-device-acme YANG module . . . . . . . . . . . . . . 19
7.1. Tree View . . . . . . . . . . . . . . . . . . . . . . . . 19
7.2. Complete Tree View . . . . . . . . . . . . . . . . . . . 20
7.3. Concepts . . . . . . . . . . . . . . . . . . . . . . . . 21
7.4. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 22
8. Security Considerations . . . . . . . . . . . . . . . . . . . 23
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24
9.1. The IETF XML Registry . . . . . . . . . . . . . . . . . . 24
9.2. The YANG Module Names Registry . . . . . . . . . . . . . 25
10. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . . 25
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 25
11.1. Normative References . . . . . . . . . . . . . . . . . . 25
11.2. Informative References . . . . . . . . . . . . . . . . . 26
Appendix A. Changes between revisions . . . . . . . . . . . . . 26
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 27
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27
Claise, et al. Expires October 25, 2021 [Page 2]
Internet-Draft YANG Modules for Service Assurance April 2021
1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
The terms used in this document are defined in draft-claise-opsawg-
service-assurance-architecture IETF draft.
2. Introduction
The "Service Assurance for Intent-based Networking Architecture"
draft-claise-opsawg-service-assurance-architecture, specifies the
framework and all of its components for service assurance. This
document complements the architecture by providing open interfaces
between components. More specifically, the goal is to provide YANG
modules for the purpose of service assurance in a format that is:
o machine readable
o vendor independent
o augmentable
3. YANG Models Overview
The main YANG module, ietf-service-assurance, defines objects for
assuring network services based on their decomposition into so-called
subservices. The subservices are hierarchically organised by
dependencies. The subservices, along with the dependencies,
constitute an assurance graph. This module should be supported by an
agent, able to interact with the devices in order to produce a health
status and symptoms for each subservice in the assurance graph. This
module is intended for the following use cases:
o Assurance graph configuration:
* Subservices: configure a set of subservices to assure, by
specifying their types and parameters.
* Dependencies: configure the dependencies between the
subservices, along with their type.
o Assurance telemetry: export the health status of the subservices,
along with the observed symptoms.
Claise, et al. Expires October 25, 2021 [Page 3]
Internet-Draft YANG Modules for Service Assurance April 2021
The second YANG module, ietf-service-assurance-device, extends the
ietf-service-assurance module to add support for the subservice
DeviceHealthy. Additional subservice types might be added the same
way.
The third YANG module, example-service-assurance-device-acme, extends
the ietf-service-assurance-device module as an example to add support
for the subservice DeviceHealthy, with specifics for the fictional
ACME Corporation. Additional vendor-specific parameters might be
added the same way.
4. Base ietf-service-assurance YANG module
4.1. Tree View
The following tree diagram [RFC8340] provides an overview of the
ietf-service-assurance data model.
module: ietf-service-assurance
+--ro assurance-graph-version yang:counter32
+--ro assurance-graph-last-change yang:date-and-time
+--rw subservices
+--rw subservice* [type id]
+--rw type identityref
+--rw id string
+--ro last-change? yang:date-and-time
+--ro label? string
+--rw under-maintenance? boolean
+--rw maintenance-contact string
+--rw (parameter)?
| +--:(service-instance-parameter)
| +--rw service-instance-parameter
| +--rw service? string
| +--rw instance-name? string
+--ro health-score? uint8
+--ro symptoms-history-start? yang:date-and-time
+--rw symptoms
| +--ro symptom* [start-date-time id]
| +--ro id string
| +--ro health-score-weight? uint8
| +--ro description? string
| +--ro start-date-time yang:date-and-time
| +--ro stop-date-time? yang:date-and-time
+--rw dependencies
+--rw dependency* [type id]
+--rw type -> /subservices/subservice/type
+--rw id -> /subservices/subservice[type=current()/../type]/id
+--rw dependency-type? identityref
Claise, et al. Expires October 25, 2021 [Page 4]
Internet-Draft YANG Modules for Service Assurance April 2021
4.2. Concepts
The ietf-service-assurance YANG model assumes an identified number of
subservices, to be assured independently. A subservice is a feature
or a subpart of the network system that a given service instance
might depend on. Example of subservices include:
o DeviceHealthy: whether a device is healthy, and if not, what are
the symptoms. Potential symptoms are "CPU overloaded", "Out of
RAM", or "Out of TCAM".
o ConnectivityHealthy: given two IP addresses owned by two devices,
what is the quality of the connection between them. Potential
symptoms are "No route available" or "ECMP Imbalance".
The first example is a subservice representing a subpart of the
network system, while the second is a subservice representing a
feature of the network, In both cases, these subservices might depend
on other subservices, for instance, the connectivity might depend on
a subservice representing the routing mechanism and on a subservice
representing ECMP.
The symptoms are listed for each subservice. Each symptom is
specified by a unique id and contains a health-score-weight (the
impact to the health score incurred by this symptom), a label (text
describing what the symptom is), and dates and times at which the
symptom was detected and stopped being detected. While the unique id
is sufficient as an unique key list, the start-date-time second key
help sorting and retrieving relevant symptoms.
The assurance of a given service instance can be obtained by
composing the assurance of the subservices that it depends on, via
the dependency relations.
In order to declare a subservice MUST provide:
o A type: identity inheriting of the base identity for subservice,
o An id: string uniquely identifying the subservice among those with
the same identity,
o Some parameters, which should be specified in an augmenting model,
as described in the next sections.
The type and id uniquely identify a given subservice. They are used
to indicate the dependencies. Dependencies have types as well. Two
types are specified in the model:
Claise, et al. Expires October 25, 2021 [Page 5]
Internet-Draft YANG Modules for Service Assurance April 2021
o Impacting: such a dependency indicates an impact on the health of
the dependent,
o Informational: such a dependency might explain why the dependent
has issues but does not impact its health.
To illustrate the difference between "impacting" and "informational",
consider the subservice InterfaceHealthy, representing a network
interface. If the device to which the network interface belongs goes
down, the network interface will transition to a down state as well.
Therefore, the dependency of InterfaceHealthy towards DeviceHealthy
is "impacting". On the other hand, as a the dependency towards the
ECMPLoad subservice, which checks that the load between ECMP remains
ce remains stable throughout time, is only "informational". Indeed,
services might be perfectly healthy even if the load distribution
between ECMP changed. However, such an instability might be a
relevant symptom for diagnosing the root cause of a problem.
Service instances MUST be modeled as a particular type of subservice
with two parameters, a type and an instance name. The type is the
name of the service defined in the network orchestrator, for instance
"point-to-point-l2vpn". The instance name is the name assigned to
the particular instance that we are assuring, for instance the name
of the customer using that instance.
The "under-maintenance" and "maintenance-contact" flags inhibit the
emission of symptoms for that subservice and subservices that depend
on them. See Section 3.7 of
[draft-claise-opsawg-service-assurance-architecture] for a more
detailed discussion.
By specifying service instances and their dependencies in terms of
subservices, one defines the whole assurance to apply for them. An
assurance agent supporting this model should then produce telemetry
in return with, for each subservice: a health-status indicating how
healthy the subservice is and when the subservice is not healthy, a
list of symptoms explaining why the subservice is not healthy.
4.3. YANG Module
<CODE BEGINS> file "ietf-service-assurance@2020-01-13.yang"
module ietf-service-assurance {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-service-assurance";
prefix service-assurance;
import ietf-yang-types {
Claise, et al. Expires October 25, 2021 [Page 6]
Internet-Draft YANG Modules for Service Assurance April 2021
prefix yang;
}
organization
"IETF NETCONF (Network Configuration) Working Group";
contact
"WG Web: <https://datatracker.ietf.org/wg/netconf/>
WG List: <mailto:netconf@ietf.org>
Author: Benoit Claise <mailto:bclaise@cisco.com>
Author: Jean Quilbeuf <mailto:jquilbeu@cisco.com>";
description
"This module defines objects for assuring network services based on
their decomposition into so-called subservices, according to the SAIN
(Service Assurance for Intent-based Networking) architecture.
The subservices hierarchically organised by dependencies constitute an
assurance graph. This module should be supported by an assurance agent,
able to interact with the devices in order to produce a health status
and symptoms for each subservice in the assurance graph.
This module is intended for the following use cases:
* Assurance graph configuration:
* subservices: configure a set of subservices to assure, by specifying
their types and parameters.
* dependencies: configure the dependencies between the subservices,
along with their type.
* Assurance telemetry: export the health status of the subservices, along
with the observed symptoms.
The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL',
'SHALL NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED',
'NOT RECOMMENDED', 'MAY', and 'OPTIONAL' in this document
are to be interpreted as described in BCP 14 (RFC 2119)
(RFC 8174) when, and only when, they appear in all
capitals, as shown here.
Copyright (c)2020 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject
to the license terms contained in, the Simplified BSD License
set forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX; see the
RFC itself for full legal notices.
Claise, et al. Expires October 25, 2021 [Page 7]
Internet-Draft YANG Modules for Service Assurance April 2021
TO DO:
- Better type (IETF or OC) for device-id, interface-id, etc.
- Have a YANG module for IETF and one for OC?";
revision 2020-01-13 {
description
"Added the maintenance window concept.";
reference
"RFC xxxx: Title to be completed";
}
revision 2019-11-16 {
description
"Initial revision.";
reference
"RFC xxxx: Title to be completed";
}
identity subservice-idty {
description
"Root identity for all subservice types.";
}
identity service-instance-idty {
base subservice-idty;
description
"Identity representing a service instance.";
}
identity dependency-type {
description
"Base identity for representing dependency types.";
}
identity informational-dependency {
base dependency-type;
description
"Indicates that symptoms of the dependency might be of interest for the
dependent, but the status of the dependency should not have any
impact on the dependent.";
}
identity impacting-dependency {
base dependency-type;
description
"Indicates that the status of the dependency directly impacts the status
of the dependent.";
}
Claise, et al. Expires October 25, 2021 [Page 8]
Internet-Draft YANG Modules for Service Assurance April 2021
grouping symptom {
description
"Contains the list of symptoms for a specific subservice.";
leaf id {
type string;
description
"A unique identifier for the symptom.";
}
leaf health-score-weight {
type uint8 {
range "0 .. 100";
}
description
"The weight to the health score incurred by this symptom. The higher the
value, the more of an impact this symptom has. If a subservice health
score is not 100, there must be at least one symptom with a health
score weight larger than 0.";
}
leaf description {
type string;
description
"Description of the symptom, i.e. text describing what the symptom is, to
be computer-consumable and be displayed on a human interface. ";
}
leaf start-date-time {
type yang:date-and-time;
description
"Date and time at which the symptom was detected.";
}
leaf stop-date-time {
type yang:date-and-time;
description
"Date and time at which the symptom stopped being detected.";
}
}
grouping subservice-dependency {
description
"Represent a dependency to another subservice.";
leaf type {
type leafref {
path "/subservices/subservice/type";
}
description
"The type of the subservice to refer to (e.g. DeviceHealthy).";
}
leaf id {
type leafref {
Claise, et al. Expires October 25, 2021 [Page 9]
Internet-Draft YANG Modules for Service Assurance April 2021
path "/subservices/subservice[type=current()/../type]/id";
}
description
"The identifier of the subservice to refer to.";
}
leaf dependency-type {
type identityref {
base dependency-type;
}
description
"Represents the type of dependency (i.e. informational, impacting).";
}
// augment here if more info are needed (i.e. a percentage) depending on the dependency type.
}
leaf assurance-graph-version {
type yang:counter32;
mandatory true;
config false;
description
"The assurance graph version, which increases by 1 for each new version, after the changes
(dependencies and/or maintenance windows parameters) are applied to the subservice(s).";
}
leaf assurance-graph-last-change {
type yang:date-and-time;
mandatory true;
config false;
description
"Date and time at which the assurance graph last changed after the changes (dependencies
and/or maintenance windows parameters) are applied to the subservice(s). These date and time
must be more recent or equal compared to the more recent value of any changed subservices
last-change";
}
container subservices {
description
"Root container for the subservices.";
list subservice {
key "type id";
description
"List of subservice configured.";
leaf type {
type identityref {
base subservice-idty;
}
description
"Name of the subservice, e.g. DeviceHealthy.";
}
leaf id {
Claise, et al. Expires October 25, 2021 [Page 10]
Internet-Draft YANG Modules for Service Assurance April 2021
type string;
description
"Unique identifier of the subservice instance, for each type.";
}
leaf last-change {
type yang:date-and-time;
config false;
description
"Date and time at which the assurance graph for this subservice
instance last changed, i.e. dependencies and/or maintenance windows parameters.";
}
leaf label {
type string;
config false;
description
"Label of the subservice, i.e. text describing what the subservice is to
be displayed on a human interface.";
}
leaf under-maintenance {
type boolean;
default false;
description
"An optional flag indicating whether this particular subservice is under
maintenance. Under this circumstance, the subservice symptoms and the
symptoms of its dependencies in the assurance graph should not be taken
into account. Instead, the subservice should send a 'Under Maintenance'
single symptom.
The operator changing the under-maintenance value must set the
maintenance-contact variable.
When the subservice is not under maintenance any longer, the
under-maintenance flag must return to its default value and
the under-maintenance-owner variable deleted.";
}
leaf maintenance-contact {
when "../under-maintenance = 'true'";
type string;
mandatory true;
description
"A string used to model an administratively assigned name of the
resource that changed the under-maintenance value to 'true.
It is suggested that this name contain one or more of the following:
IP address, management station name, network manager's name, location,
or phone number. In some cases the agent itself will be the owner of
an entry. In these cases, this string shall be set to a string
starting with 'monitor'.";
Claise, et al. Expires October 25, 2021 [Page 11]
Internet-Draft YANG Modules for Service Assurance April 2021
}
choice parameter {
description
"Specify the required parameters per subservice type.";
container service-instance-parameter {
when "derived-from-or-self(../type, 'service-assurance:service-instance-idty')";
description
"Specify the parameters of a service instance.";
leaf service {
type string;
description "Name of the service.";
}
leaf instance-name{
type string;
description "Name of the instance for that service.";
}
}
// Other modules can augment their own cases into here
}
leaf health-score {
type uint8 {
range "0 .. 100";
}
config false;
description
"Score value of the subservice health. A value of 100 means that
subservice is healthy. A value of 0 means that the subservice is
broken. A value between 0 and 100 means that the subservice is
degraded.";
}
leaf symptoms-history-start {
type yang:date-and-time;
config false;
description
"Date and time at which the symptoms history starts for this
subservice instance, either because the subservice instance
started at that date and time or because the symptoms before that
were removed due to a garbage collection process.";
}
container symptoms {
description
"Symptoms for the subservice.";
list symptom {
key "start-date-time id";
config false;
description
"List of symptoms the subservice. While the start-date-time key is not
necessary per se, this would get the entries sorted by start-date-time
Claise, et al. Expires October 25, 2021 [Page 12]
Internet-Draft YANG Modules for Service Assurance April 2021
for easy consumption.";
uses symptom;
}
}
container dependencies {
description
"configure the dependencies between the subservices, along with their types.";
list dependency {
key "type id";
description
"List of soft dependencies of the subservice.";
uses subservice-dependency;
}
}
}
}
}
<CODE ENDS>
5. Subservice Extension: ietf-service-assurance-device YANG module
5.1. Tree View
The following tree diagram [RFC8340] provides an overview of the
ietf-service-assurance-device data model.
module: ietf-service-assurance-device
augment /service-assurance:subservices/service-assurance:subservice/service-assurance:parameter:
+--rw device-idty
+--rw device? string
5.2. Complete Tree View
The following tree diagram [RFC8340] provides an overview of the
ietf-service-assurance and ietf-service-assurance-device data models.
Claise, et al. Expires October 25, 2021 [Page 13]
Internet-Draft YANG Modules for Service Assurance April 2021
module: ietf-service-assurance
+--ro assurance-graph-version yang:counter32
+--ro assurance-graph-last-change yang:date-and-time
+--rw subservices
+--rw subservice* [type id]
+--rw type identityref
+--rw id string
+--ro last-change? yang:date-and-time
+--ro label? string
+--rw under-maintenance? boolean
+--rw maintenance-contact string
+--rw (parameter)?
| +--:(service-instance-parameter)
| | +--rw service-instance-parameter
| | +--rw service? string
| | +--rw instance-name? string
| +--:(service-assurance-device:device-idty)
| +--rw service-assurance-device:device-idty
| +--rw service-assurance-device:device? string
+--ro health-score? uint8
+--ro symptoms-history-start? yang:date-and-time
+--rw symptoms
| +--ro symptom* [start-date-time id]
| +--ro id string
| +--ro health-score-weight? uint8
| +--ro description? string
| +--ro start-date-time yang:date-and-time
| +--ro stop-date-time? yang:date-and-time
+--rw dependencies
+--rw dependency* [type id]
+--rw type -> /subservices/subservice/type
+--rw id -> /subservices/subservice[type=current()/../type]/id
+--rw dependency-type? identityref
5.3. Concepts
As the number of subservices will grow over time, the YANG module is
designed to be extensible. A new subservice type requires the
precise specifications of its type and expected parameters. Let us
illustrate the example of the new DeviceHealthy subservice type. As
the name implies, it monitors and reports the device health, along
with some symptoms in case of degradation.
For our DeviceHealthy subservice definition, the new device-idty is
specified, as an inheritance from the base identity for subservices.
This indicates to the assurance agent that we are now assuring the
health of a device.
Claise, et al. Expires October 25, 2021 [Page 14]
Internet-Draft YANG Modules for Service Assurance April 2021
The typical parameter for the configuration of the DeviceHealthy
subservice is the name of the device that we want to assure. By
augmenting the parameter choice from ietf-service-assurance YANG
module for the case of the device-idty subservice type, this new
parameter is specified.
5.4. YANG Module
<CODE BEGINS> file "ietf-service-assurance-device@2020-01-13.yang"
module ietf-service-assurance-device {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-service-assurance-device";
prefix service-assurance-device;
import ietf-service-assurance {
prefix "service-assurance";
}
organization
"IETF NETCONF (Network Configuration) Working Group";
contact
"WG Web: <https://datatracker.ietf.org/wg/netconf/>
WG List: <mailto:netconf@ietf.org>
Author: Benoit Claise <mailto:bclaise@cisco.com>
Author: Jean Quilbeuf <mailto:jquilbeu@cisco.com>";
description
"This module extends the ietf-service-assurance module to add
support for the subservice DeviceHealthy.
Checks whether a network device is healthy.
The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL',
'SHALL NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED',
'NOT RECOMMENDED', 'MAY', and 'OPTIONAL' in this document
are to be interpreted as described in BCP 14 (RFC 2119)
(RFC 8174) when, and only when, they appear in all
capitals, as shown here.
Copyright (c) 2020 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject
to the license terms contained in, the Simplified BSD License
set forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(https://trustee.ietf.org/license-info).
Claise, et al. Expires October 25, 2021 [Page 15]
Internet-Draft YANG Modules for Service Assurance April 2021
This version of this YANG module is part of RFC XXXX; see the
RFC itself for full legal notices. ";
revision 2020-01-13 {
description
"Added the maintenance window concept.";
reference
"RFC xxxx: Title to be completed";
}
revision 2019-11-16 {
description
"Initial revision.";
reference
"RFC xxxx: Title to be completed";
}
identity device-idty {
base service-assurance:subservice-idty;
description "Network Device is healthy.";
}
augment /service-assurance:subservices/service-assurance:subservice/service-assurance:parameter {
description
"Specify the required parameters for a new subservice type";
container device-idty{
when "derived-from-or-self(../service-assurance:type, 'device-idty')";
description
"Specify the required parameters for the device-idty subservice type";
leaf device {
type string;
description "The device to monitor.";
}
}
}
}
<CODE ENDS>
6. Subservice Extension: ietf-service-assurance-interface YANG module
6.1. Tree View
The following tree diagram [RFC8340] provides an overview of the
ietf-service-assurance-interface data model.
Claise, et al. Expires October 25, 2021 [Page 16]
Internet-Draft YANG Modules for Service Assurance April 2021
module: ietf-service-assurance-interface
augment /service-assurance:subservices/service-assurance:subservice/service-assurance:parameter:
+--rw device? string
+--rw interface? string
6.2. Complete Tree View
The following tree diagram [RFC8340] provides an overview of the
ietf-service-assurance, ietf-service-assurance-device, and ietf-
service-assurance-interface data models.
module: ietf-service-assurance
+--ro assurance-graph-version yang:counter32
+--ro assurance-graph-last-change yang:date-and-time
+--rw subservices
+--rw subservice* [type id]
+--rw type identityref
+--rw id string
+--ro last-change? yang:date-and-time
+--ro label? string
+--rw under-maintenance? boolean
+--rw maintenance-contact string
+--rw (parameter)?
| +--:(service-instance-parameter)
| | +--rw service-instance-parameter
| | +--rw service? string
| | +--rw instance-name? string
| +--:(service-assurance-device:device-idty)
| | +--rw service-assurance-device:device-idty
| | +--rw service-assurance-device:device? string
| +--:(service-assurance-interface:device)
| | +--rw service-assurance-interface:device? string
| +--:(service-assurance-interface:interface)
| +--rw service-assurance-interface:interface? string
+--ro health-score? uint8
+--ro symptoms-history-start? yang:date-and-time
+--rw symptoms
| +--ro symptom* [start-date-time id]
| +--ro id string
| +--ro health-score-weight? uint8
| +--ro description? string
| +--ro start-date-time yang:date-and-time
| +--ro stop-date-time? yang:date-and-time
+--rw dependencies
+--rw dependency* [type id]
+--rw type -> /subservices/subservice/type
+--rw id -> /subservices/subservice[type=current()/../type]/id
+--rw dependency-type? identityref
Claise, et al. Expires October 25, 2021 [Page 17]
Internet-Draft YANG Modules for Service Assurance April 2021
6.3. Concepts
For our InterafaceHealthy subservice definition, the new interface-
idty is specified, as an inheritance from the base identity for
subservices. This indicates to the assurance agent that we are now
assuring the health of an interface.
The typical parameters for the configuration of the InterfaceHealthy
subservice are the name of the device and, on that specific device, a
specific interface. By augmenting the parameter choice from ietf-
service-assurance YANG module for the case of the interface-idty
subservice type, those two new parameter are specified.
6.4. YANG Module
<CODE BEGINS> file "ietf-service-assurance-interface@2020-01-13.yang"
module ietf-service-assurance-interface {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-service-assurance-interface";
prefix service-assurance-interface;
import ietf-service-assurance {
prefix "service-assurance";
}
organization
"IETF OPSAWG Working Group";
contact
"WG Web: <https://datatracker.ietf.org/wg/opsawg/>
WG List: <mailto:opsawg@ietf.org>
Author: Benoit Claise <mailto:bclaise@cisco.com>
Author: Jean Quilbeuf <mailto:jquilbeu@cisco.com>";
description
"This module extends the ietf-service-assurance module to add
support for the subservice InterfaceHealthy.
Checks whether an interface is healthy.
The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL',
'SHALL NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED',
'NOT RECOMMENDED', 'MAY', and 'OPTIONAL' in this document
are to be interpreted as described in BCP 14 (RFC 2119)
(RFC 8174) when, and only when, they appear in all
capitals, as shown here.
Copyright (c) 2020 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Claise, et al. Expires October 25, 2021 [Page 18]
Internet-Draft YANG Modules for Service Assurance April 2021
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject
to the license terms contained in, the Simplified BSD License
set forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX; see the
RFC itself for full legal notices. ";
revision 2020-01-13 {
description
"Initial revision.";
reference
"RFC xxxx: Title to be completed";
}
identity interface-idty {
base service-assurance:subservice-idty;
description "Checks whether an interface is healthy.";
}
augment /service-assurance:subservices/service-assurance:subservice/service-assurance:parameter {
when "derived-from-or-self(service-assurance:type, 'interface-idty')";
description
"Specify the required parameters for the interface-idty subservice type";
leaf device {
type string;
description "Device supporting the interface.";
}
leaf interface {
type string;
description "Name of the interface.";
}
}
}
<CODE ENDS>
7. Vendor-specific Subservice Extension: example-service-assurance-
device-acme YANG module
7.1. Tree View
The following tree diagram [RFC8340] provides an overview of the
example-service-assurance-device-acme data model.
Claise, et al. Expires October 25, 2021 [Page 19]
Internet-Draft YANG Modules for Service Assurance April 2021
module: example-service-assurance-device-acme
augment /service-assurance:subservices/service-assurance:subservice/service-assurance:parameter:
+--rw acme-device-idty
+--rw device? string
+--rw acme-specific-parameter? string
7.2. Complete Tree View
The following tree diagram [RFC8340] provides an overview of the
ietf-service-assurance, ietf-service-assurance-device, and example-
service-assurance-device-acme data models.
Claise, et al. Expires October 25, 2021 [Page 20]
Internet-Draft YANG Modules for Service Assurance April 2021
module: ietf-service-assurance
+--ro assurance-graph-version yang:counter32
+--ro assurance-graph-last-change yang:date-and-time
+--rw subservices
+--rw subservice* [type id]
+--rw type identityref
+--rw id string
+--ro last-change? yang:date-and-time
+--ro label? string
+--rw under-maintenance? boolean
+--rw maintenance-contact string
+--rw (parameter)?
| +--:(service-instance-parameter)
| | +--rw service-instance-parameter
| | +--rw service? string
| | +--rw instance-name? string
| +--:(service-assurance-device:device-idty)
| | +--rw service-assurance-device:device-idty
| | +--rw service-assurance-device:device? string
| +--:(service-assurance-interface:device)
| | +--rw service-assurance-interface:device? string
| +--:(service-assurance-interface:interface)
| | +--rw service-assurance-interface:interface? string
| +--:(example-service-assurance-device-acme:acme-device-idty)
| +--rw example-service-assurance-device-acme:acme-device-idty
| +--rw example-service-assurance-device-acme:device? string
| +--rw example-service-assurance-device-acme:acme-specific-parameter? string
+--ro health-score? uint8
+--ro symptoms-history-start? yang:date-and-time
+--rw symptoms
| +--ro symptom* [start-date-time id]
| +--ro id string
| +--ro health-score-weight? uint8
| +--ro description? string
| +--ro start-date-time yang:date-and-time
| +--ro stop-date-time? yang:date-and-time
+--rw dependencies
+--rw dependency* [type id]
+--rw type -> /subservices/subservice/type
+--rw id -> /subservices/subservice[type=current()/../type]/id
+--rw dependency-type? identityref
7.3. Concepts
Under some circumstances, vendor-specific subservice types might be
required. As an example of this vendor-specific implementation, this
section shows how to augment the ietf-service-assurance-device module
Claise, et al. Expires October 25, 2021 [Page 21]
Internet-Draft YANG Modules for Service Assurance April 2021
to add support for the subservice DeviceHealthy, specific to the ACME
Corporation. The new parameter is acme-specific-parameter.
7.4. YANG Module
module example-service-assurance-device-acme {
yang-version 1.1;
namespace "urn:example:example-service-assurance-device-acme";
prefix example-service-assurance-device-acme;
import ietf-service-assurance {
prefix "service-assurance";
}
import ietf-service-assurance-device {
prefix "service-assurance-device";
}
organization
"IETF NETCONF (Network Configuration) Working Group";
contact
"WG Web: <https://datatracker.ietf.org/wg/netconf/>
WG List: <mailto:netconf@ietf.org>
Author: Benoit Claise <mailto:bclaise@cisco.com>
Author: Jean Quilbeuf <mailto:jquilbeu@cisco.com>";
description
"This module extends the ietf-service-assurance-device module to add
support for the subservice DeviceHealthy, specific to the ACME Corporation.
ACME Network Device is healthy.
The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL',
'SHALL NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED',
'NOT RECOMMENDED', 'MAY', and 'OPTIONAL' in this document
are to be interpreted as described in BCP 14 (RFC 2119)
(RFC 8174) when, and only when, they appear in all
capitals, as shown here.
Copyright (c) 2019 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject
to the license terms contained in, the Simplified BSD License
set forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(https://trustee.ietf.org/license-info).
Claise, et al. Expires October 25, 2021 [Page 22]
Internet-Draft YANG Modules for Service Assurance April 2021
This version of this YANG module is part of RFC XXXX; see the
RFC itself for full legal notices. ";
revision 2020-01-13 {
description
"Added the maintenance window concept.";
reference
"RFC xxxx: Title to be completed";
}
revision 2019-11-16 {
description
"Initial revision.";
reference
"RFC xxxx: Title to be completed";
}
identity device-acme-idty {
base service-assurance-device:device-idty;
description "Network Device is healthy.";
}
augment /service-assurance:subservices/service-assurance:subservice/service-assurance:parameter {
description
"Specify the required parameters for a new subservice type";
container acme-device-idty{
when "derived-from-or-self(../service-assurance:type, 'device-acme-idty')";
description
"Specify the required parameters for the device-acme-idty subservice type";
leaf device {
type string;
description "The device to monitor.";
}
leaf acme-specific-parameter {
type string;
description "The ACME Corporation sepcific parameter.";
}
}
}
}
8. Security Considerations
The YANG module specified in this document defines a schema for data
that is designed to be accessed via network management protocols such
as NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer
Claise, et al. Expires October 25, 2021 [Page 23]
Internet-Draft YANG Modules for Service Assurance April 2021
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].
The Network Configuration Access Control Model (NACM) [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.
There are a number of data nodes defined in this YANG module that are
writable/ creatable/deletable (i.e., config true, which is the
default). These data nodes may be considered sensitive or vulnerable
in some network environments. Write operations (e.g., edit-config)
to these data nodes without proper protection can have a negative
effect on network operations. These are the subtrees and data nodes
and their sensitivity/vulnerability:
o /subservices/subservice/type
o /subservices/subservice/id
o /subservices/subservice/under-maintenance
o /subservices/subservice/maintenance-contact
9. IANA Considerations
9.1. The IETF XML Registry
This document registers two URIs in the IETF XML registry [RFC3688].
Following the format in [RFC3688], the following registrations are
requested:
URI: urn:ietf:params:xml:ns:yang:ietf-service-assurance
Registrant Contact: The NETCONF WG of the IETF.
XML: N/A, the requested URI is an XML namespace.
URI: urn:ietf:params:xml:ns:yang:ietf-service-assurance-device
Registrant Contact: The NETCONF WG of the IETF.
XML: N/A, the requested URI is an XML namespace.
URI: urn:ietf:params:xml:ns:yang:ietf-service-assurance-interface
Registrant Contact: The NETCONF WG of the IETF.
XML: N/A, the requested URI is an XML namespace.
Claise, et al. Expires October 25, 2021 [Page 24]
Internet-Draft YANG Modules for Service Assurance April 2021
9.2. The YANG Module Names Registry
This document registers three YANG modules in the YANG Module Names
registry [RFC7950]. Following the format in [RFC7950], the the
following registrations are requested:
name: ietf-service-assurance
namespace: urn:ietf:params:xml:ns:yang:ietf-service-assurance
prefix: inc
reference: RFC XXXX
name: ietf-service-assurance-device
namespace: urn:ietf:params:xml:ns:yang:ietf-service-assurance-device
prefix: inc
reference: RFC XXXX
name: ietf-service-assurance-interface
namespace: urn:ietf:params:xml:ns:yang:ietf-service-assurance-interface
prefix: inc
reference: RFC XXXX
10. Open Issues
-None
11. References
11.1. Normative References
[draft-claise-opsawg-service-assurance-architecture]
Claise, B. and J. Quilbeuf, "draft-claise-opsawg-service-
assurance-architecture", 2020.
[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>.
Claise, et al. Expires October 25, 2021 [Page 25]
Internet-Draft YANG Modules for Service Assurance April 2021
[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>.
[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>.
11.2. Informative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<https://www.rfc-editor.org/info/rfc3688>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
<https://www.rfc-editor.org/info/rfc8340>.
Appendix A. Changes between revisions
v04 - v05
o Added the concept of symptoms-history-start
o Changed label to description, under symptoms. This was confusing
as there was two labels in the models
v03 - v04
o Add the interface subservice, with two parameters
v02 - v03
o Added the maintenace window concepts
Claise, et al. Expires October 25, 2021 [Page 26]
Internet-Draft YANG Modules for Service Assurance April 2021
v01 - v02
o Improved leaf naming
o Clarified some concepts: symptoms, dependency
v00 - v01
o Terminology clarifications
o Provide example of impacting versus impacted dependencies
Acknowledgements
The authors would like to thank Jan Lindblad for his help during the
design of these YANG modules. The authors would like to thank
Stephane Litkowski and Charles Eckel for their reviews.
Authors' Addresses
Benoit Claise
Huawei
Email: benoit.claise@huawei.com
Jean Quilbeuf
Independent
Email: jean@quilbeuf.net
Paolo Lucente
NTT
Siriusdreef 70-72
Hoofddorp, WT 2132
Netherlands
Email: paolo@ntt.net
Paolo Fasano
TIM S.p.A
via G. Reiss Romoli, 274
10148 Torino
Italy
Email: paolo2.fasano@telecomitalia.it
Claise, et al. Expires October 25, 2021 [Page 27]
Internet-Draft YANG Modules for Service Assurance April 2021
Thangam Arumugam
Cisco Systems, Inc.
Milpitas (California)
United States
Email: tarumuga@cisco.com
Claise, et al. Expires October 25, 2021 [Page 28]