Internet DRAFT - draft-ietf-netmod-nmda-diff
draft-ietf-netmod-nmda-diff
Network Working Group A. Clemm
Internet-Draft Y. Qu
Intended status: Standards Track Futurewei
Expires: February 7, 2022 J. Tantsura
Microsoft
A. Bierman
YumaWorks
August 6, 2021
Comparison of NMDA datastores
draft-ietf-netmod-nmda-diff-12
Abstract
This document defines an RPC operation to compare management
datastores that comply with the NMDA 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 February 7, 2022.
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
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Key Words . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Definitions and Acronyms . . . . . . . . . . . . . . . . . . 3
4. Data Model Overview . . . . . . . . . . . . . . . . . . . . . 4
5. YANG Data Model . . . . . . . . . . . . . . . . . . . . . . . 6
6. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
7. Performance Considerations . . . . . . . . . . . . . . . . . 14
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
8.1. Updates to the IETF XML Registry . . . . . . . . . . . . 15
8.2. Updates to the YANG Module Names Registry . . . . . . . . 15
9. Security Considerations . . . . . . . . . . . . . . . . . . . 15
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 16
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
11.1. Normative References . . . . . . . . . . . . . . . . . . 16
11.2. Informative References . . . . . . . . . . . . . . . . . 18
Appendix A. Possible Future Extensions . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18
1. Introduction
The revised Network Management Datastore Architecture (NMDA)
[RFC8342] introduces a set of new datastores that each hold YANG-
defined data [RFC7950] and represent a different "viewpoint" on the
data that is maintained by a server. New YANG datastores that are
introduced include <intended>, which contains validated configuration
data that a client application intends to be in effect, and
<operational>, which contains operational state data (such as
statistics) as well as configuration data that is actually in effect.
NMDA introduces in effect a concept of "lifecycle" for management
data, distinguishing between data that is part of a configuration
that was supplied by a user, configuration data that has actually
been successfully applied and that is part of the operational state,
and overall operational state that includes applied configuration
data as well as status and statistics.
As a result, data from the same management model can be reflected in
multiple datastores. Clients need to specify the target datastore to
be specific about which viewpoint of the data they want to access.
For example, a client application can differentiate whether they are
interested in the configuration supplied to a server and that is
supposed to be in effect, or the configuration that has been applied
and is actually in effect on the server.
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Due to the fact that data can propagate from one datastore to
another, it is possible for differences between datastores to occur.
Some of this is entirely expected, as there may be a time lag between
when a configuration is given to the device and reflected in
<intended>, until when it actually takes effect and is reflected in
<operational>. However, there may be cases when a configuration item
that was to be applied may not actually take effect at all or needs
an unusually long time to do so. This can be the case due to certain
conditions not being met, certain parts of the configuration not
propagating because they are considered inactive, resource
dependencies not being resolved, or even implementation errors in
corner conditions.
When configuration that is in effect is different from configuration
that was applied, many issues can result. It becomes more difficult
to operate the network properly due to limited visibility of actual
operational status which makes it more difficult to analyze and
understand what is going on in the network. Services may be
negatively affected (for example, degrading or breaking a customer
service) and network resources may be misallocated.
Applications can potentially analyze any differences between two
datastores by retrieving the contents from both datastores and
comparing them. However, in many cases this will be at the same time
costly and extremely wasteful.
This document introduces a YANG data model which defines RPCs,
intended to be used in conjunction with NETCONF [RFC6241] or RESTCONF
[RFC8040], that allow a client to request a server to compare two
NMDA datastores and report any differences.
2. Key Words
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. Definitions and Acronyms
NMDA: Network Management Datastore Architecture
RPC: Remote Procedure Call
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4. Data Model Overview
The core of the solution is a new management operation, <compare>,
that compares the data tree contents of two datastores. The
operation checks whether there are any differences in values or in
data nodes that are contained in either datastore, and returns any
differences as output. The output is returned in the format
specified in YANG-Patch [RFC8072].
The YANG data model defines the <compare> operation as a new RPC.
The operation takes the following input parameters:
o source: The source identifies the datastore that will serve as the
reference for the comparison, for example <intended>.
o target: The target identifies the datastore to compare against the
source, for example <operational>.
o filter-spec: This is a choice between different filter constructs
to identify the parts of the datastore to be retrieved. It acts
as a node selector that specifies which data nodes are within the
scope of the comparison and which nodes are outside the scope.
This allows a comparison operation to be applied only to a
specific part of the datastore that is of interest, such as a
particular subtree. Note, the filter does not allow expressions
that match against data node values, since this may incur
implementation difficulties and is not required for normal use
cases.
o all: When set, this parameter indicates that all differences
should be included, including differences pertaining to schema
nodes that exist in only one of the datastores. When this
parameter is not included, a prefiltering step is automatically
applied to exclude data from the comparison that does not pertain
to both datastores: if the same schema node is not present in both
datastores, then all instances of that schema node and all its
descendants are excluded from the comparison. This allows client
applications to focus on the differences that constitute true
mismatches of instance data without needing to specify more
complex filter constructs.
o report-origin: When set, this parameter indicates that origin
metadata should be included as part of RPC output. When this
parameter is omitted, origin metadata in comparisons that involve
<operational> is by default omitted. Note that origin metadata
only applies to <operational> it is therefore also omitted in
comparisons that do not involve <operational> regardless of
whether or not the parameter is set.
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The operation provides the following output parameter:
o differences: This parameter contains the list of differences.
Those differences are encoded per the YANG-Patch data model
defined in RFC8072. When a datastore node in the source of the
comparison is not present in the target of the comparison, this
can be indicated either as a "delete" or as a "remove" in the
patch as there is no differentiation between those operations for
the purposes of the comparison. The YANG-Patch data model is
augmented to indicate the value of source datastore nodes in
addition to the patch itself that would need to be applied to the
source to produce the target. When the target datastore is
<operational> and the input parameter "report-origin" is set,
"origin" metadata is included as part of the patch. Including
origin metadata can help in some cases explain the cause of a
difference, for example when a data node is part of <intended> but
the origin of the same data node in <operational> is reported as
"system".
The data model is defined in the ietf-nmda-compare YANG module. Its
structure is shown in the following figure. The notation syntax
follows [RFC8340].
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module: ietf-nmda-compare
rpcs:
+---x compare
+---w input
| +---w source identityref
| +---w target identityref
| +---w all? empty
| +---w report-origin? empty
| +---w (filter-spec)?
| +--:(subtree-filter)
| | +---w subtree-filter?
| +--:(xpath-filter)
| +---w xpath-filter? yang:xpath1.0 {nc:xpath}?
+--ro output
+--ro (compare-response)?
+--:(no-matches)
| +--ro no-matches? empty
+--:(differences)
+--ro differences
+--ro yang-patch
+--ro patch-id string
+--ro comment? string
+--ro edit* [edit-id]
+--ro edit-id string
+--ro operation enumeration
+--ro target target-resource-offset
+--ro point? target-resource-offset
+--ro where? enumeration
+--ro value?
+--ro source-value?
Structure of ietf-nmda-compare
5. YANG Data Model
<CODE BEGINS> file "ietf-nmda-compare@2021-08-06.yang"
module ietf-nmda-compare {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-nmda-compare";
prefix cmp;
import ietf-yang-types {
prefix yang;
reference "RFC 6991: Common YANG Data Types";
}
import ietf-datastores {
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prefix ds;
reference "RFC 8342: Network Management Datastore
Architecture (NMDA)";
}
import ietf-yang-patch {
prefix ypatch;
reference "RFC 8072: YANG Patch Media Type";
}
import ietf-netconf {
prefix nc;
reference "RFC6241: Network Configuration Protocol (NETCONF)";
}
organization "IETF";
contact
"WG Web: <https://datatracker.ietf.org/wg/netconf/>
WG List: <mailto:netconf@ietf.org>
Author: Alexander Clemm
<mailto:ludwig@clemm.org>
Author: Yingzhen Qu
<mailto:yqu@futurewei.com>
Author: Jeff Tantsura
<mailto:jefftant.ietf@gmail.com>
Author: Andy Bierman
<mailto:andy@yumaworks.com>";
description
"The YANG data model defines a new operation, <compare>, that
can be used to compare NMDA datastores.
Copyright (c) 2021 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
draft-ietf-netmod-nmda-diff-12; see the RFC itself for full
legal notices.
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NOTE TO RFC EDITOR: Please replace above reference to
draft-ietf-netmod-nmda-diff-12 with RFC number when published
(i.e. RFC xxxx).";
revision 2021-08-06 {
description
"Initial revision.
NOTE TO RFC EDITOR:
(1)Please replace the above revision date to
the date of RFC publication when published.
(2) Please replace the date in the file name
(ietf-nmda-compare@2021-08-06.yang) to the date of RFC
publication.
(3) Please replace the following reference to
draft-ietf-netmod-nmda-diff-12 with RFC number when published
(i.e. RFC xxxx).";
reference
"draft-ietf-netmod-nmda-diff-12: Comparison of NMDA
datastores";
}
/* RPC */
rpc compare {
description
"NMDA datastore compare operation.";
input {
leaf source {
type identityref {
base ds:datastore;
}
mandatory true;
description
"The source datastore to be compared.";
}
leaf target {
type identityref {
base ds:datastore;
}
mandatory true;
description
"The target datastore to be compared.";
}
leaf all {
type empty;
description
"When this leaf is provided, all data nodes are compared,
whether their schema node pertains to both datastores or
not. When this leaf is omitted, a prefiltering step is
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automatically applied that excludes data nodes from the
comparison that can occur in only one datastore but not
the other. Specifically, if one of the datastores
(source or target) contains only configuration data and
the other datastore is <operational>, data nodes for
which config is false are excluded from the comparison.";
}
leaf report-origin {
type empty;
description
"When this leaf is provided, origin metadata is
included as part of RPC output. When this leaf is
omitted, origin metadata in comparisons that involve
<operational> is by default omitted.";
}
choice filter-spec {
description
"Identifies the portions of the datastores to be
compared.";
anydata subtree-filter {
description
"This parameter identifies the portions of the
target datastore to retrieve.";
reference "RFC 6241, Section 6.";
}
leaf xpath-filter {
if-feature nc:xpath;
type yang:xpath1.0;
description
"This parameter contains an XPath expression
identifying the portions of the target
datastore to retrieve.";
reference "RFC 6991: Common YANG Data Types";
}
}
}
output {
choice compare-response {
description
"Comparison results.";
leaf no-matches {
type empty;
description
"This leaf indicates that the filter did not match
anything and nothing was compared.";
}
container differences {
description
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"The list of differences, encoded per RFC8072 with an
augmentation to include source values where applicable.
When a datastore node in the source is not present in
the target, this can be indicated either as a 'delete'
or as a 'remove' as there is no difference between
them for the purposes of the comparison.";
uses ypatch:yang-patch {
augment "yang-patch/edit" {
description
"Provide the value of the source of the patch,
respectively of the comparison, in addition to
the target value, where applicable.";
anydata source-value {
when "../operation = 'delete'"
+ "or ../operation = 'merge'"
+ "or ../operation = 'move'"
+ "or ../operation = 'replace'"
+ "or ../operation = 'remove'";
description
"The anydata 'value' is only used for 'delete',
'move', 'merge', 'replace', and 'remove'
operations.";
}
reference "RFC 8072: YANG Patch Media Type";
}
}
}
}
}
}
}
<CODE ENDS>
6. Example
The following example compares the difference between <operational>
and <intended> for a subtree under "interfaces". The subtree
contains a subset of objects that are defined in a YANG data model
for the management of interfaces defined in [RFC8343]. For the
purposes of understanding the subsequent example, the following
excerpt of the data model whose instantiation is the basis of the
comparison is provided:
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container interfaces {
description
"Interface parameters.";
list interface {
key "name";
leaf name {
type string;
description
"The name of the interface".
}
leaf description {
type string;
description
"A textual description of the interface.";
}
leaf enabled {
type boolean;
default "true";
description
"This leaf contains the configured, desired state of the
interface.";"
}
}
}
The contents of <intended> and <operational> datastores:
//INTENDED
<interfaces xmlns="urn:ietf:params:xml:ns:yang:ietf-interfaces">
<interface>
<name>eth0</name>
<enabled>false</enabled>
<description>ip interface</description>
</interface>
</interfaces>
//OPERATIONAL
<interfaces
xmlns="urn:ietf:params:xml:ns:yang:ietf-interfaces"
xmlns:or="urn:ietf:params:xml:ns:yang:ietf-origin">
<interface or:origin="or:learned">
<name>eth0</name>
<enabled>true</enabled>
</interface>
</interfaces>
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<operational> does not contain an instance for leaf "description"
that is contained in <intended>. Another leaf, "enabled", has
different values in the two datastores, being "true" in <operational>
and "false" in <intended>. A third leaf, "name", is the same in both
cases. The origin of the leaf instances in <operational> is
"learned", which may help explain the discrepancies.
RPC request to compare <operational> (source of the comparison) with
<intended>(target of the comparison):
<rpc message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<compare xmlns="urn:ietf:params:xml:ns:yang:ietf-nmda-compare"
xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores">
<source>ds:operational</source>
<target>ds:intended</target>
<report-origin/>
<xpath-filter
xmlns:if="urn:ietf:params:xml:ns:yang:ietf-interfaces">
/if:interfaces
</xpath-filter>
</compare>
</rpc>
RPC reply, when a difference is detected:
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<rpc-reply
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
message-id="101">
<differences
xmlns="urn:ietf:params:xml:ns:yang:ietf-nmda-compare"
xmlns:or="urn:ietf:params:xml:ns:yang:ietf-origin">
<yang-patch>
<patch-id>interface status</patch-id>
<comment>
diff between operational (source) and intended (target)
</comment>
<edit>
<edit-id>1</edit-id>
<operation>replace</operation>
<target>/ietf-interfaces:interface=eth0/enabled</target>
<value>
<if:enabled>false<if:enabled>
</value>
<source-value>
<if:enabled or:origin="or:learned">true</if:enabled>
</source-value>
</edit>
<edit>
<edit-id>2</edit-id>
<operation>create</operation>
<target>/ietf-interfaces:interface=eth0/description</target>
<value>
<if:description>ip interface<description>
</value>
</edit>
</yang-patch>
</differences>
</rpc-reply>
The same request in RESTCONF (using JSON format):
POST /restconf/operations/ietf-nmda-compare:compare HTTP/1.1
Host: example.com
Content-Type: application/yang-data+json
Accept: application/yang-data+json
{ "ietf-nmda-compare:input" : {
"source" : "ietf-datastores:operational",
"target" : "ietf-datastores:intended",
"report-origin" : null,
"xpath-filter" : "/ietf-interfaces:interfaces"
}
}
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The same response in RESTCONF (using JSON format):
HTTP/1.1 200 OK
Date: Thu, 24 Jan 2019 20:56:30 GMT
Server: example-server
Content-Type: application/yang-data+json
{ "ietf-nmda-compare:output" : {
"differences" : {
"ietf-yang-patch:yang-patch" : {
"patch-id" : "interface status",
"comment" : "diff between intended (source) and operational",
"edit" : [
{
"edit-id" : "1",
"operation" : "replace",
"target" : "/ietf-interfaces:interface=eth0/enabled",
"value" : {
"ietf-interfaces:interface/enabled" : "false"
},
"source-value" : {
"ietf-interfaces:interface/enabled" : "true",
"@ietf-interfaces:interface/enabled" : {
"ietf-origin:origin" : "ietf-origin:learned"
}
}
},
{
"edit-id" : "2",
"operation" : "create",
"target" : "/ietf-interfaces:interface=eth0/description",
"value" : {
"ietf-interface:interface/description" : "ip interface"
}
}
]
}
}
}
}
7. Performance Considerations
The compare operation can be computationally expensive. While
responsible client applications are expected to use the operation
responsibly and sparingly only when warranted, implementations need
to be aware of the fact that excessive invocation of this operation
will burden system resources and need to ensure that system
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performance will not be adversely impacted. One possibility for an
implementation to mitigate against this is to limit the number of
requests that are served to a client, or to any number of clients, in
any one time interval, by rejecting requests made at a higher
frequency than the implementation can reasonably sustain.
While useful, tools such as YANG Data Models that allow for the
monitoring of server resources, system performance, and statistics
about RPCs and RPC rates are outside the scope of this document.
When defined, any such model should be general in nature and not
limited to the RPC operation defined in this document.
8. IANA Considerations
8.1. Updates to the IETF XML Registry
This document registers one URI in the IETF XML registry [RFC3688].
Following the format in [RFC3688], the following registration is
requested:
URI: urn:ietf:params:xml:ns:yang:ietf-nmda-compare
Registrant Contact: The IESG.
XML: N/A, the requested URI is an XML namespace.
8.2. Updates to the YANG Module Names Registry
This document registers a YANG module in the YANG Module Names
registry [RFC6020]. Following the format in [RFC6020], the following
registration is requested:
name: ietf-nmda-compare
namespace: urn:ietf:params:xml:ns:yang:ietf-nmda-compare
prefix: cmp
reference: draft-ietf-netmod-nmda-diff-12 (RFC form)
9. 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
is the secure transport layer, and the mandatory-to-implement secure
transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer
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is HTTPS, and the mandatory-to-implement secure transport is TLS
[RFC8446].
The NETCONF access control model [RFC8341] provides the means to
restrict access for particular NETCONF or RESTCONF users to a
preconfigured subset of all available NETCONF or RESTCONF protocol
operations and content.
NACM specifies access for the server in its entirety and the same
access rules apply to all datastores. Any subtrees to which a
requestor does not have read access are silently skipped and not
included in the comparison.
The RPC operation defined in this YANG module, "compare", may be
considered sensitive or vulnerable in some network environments. It
is thus important to control access to this operation. This is the
sensitivity/vulnerability of RPC operation "compare":
Comparing datastores for differences requires a certain amount of
processing resources at the server. An attacker could attempt to
attack a server by making a high volume of comparison requests.
Server implementations can guard against such scenarios in several
ways. For one, they can implement the NETCONF access control model
in order to require proper authorization for requests to be made.
Second, server implementations can limit the number of requests that
they serve to a client in any one time interval, rejecting requests
made at a higher frequency than the implementation can reasonably
sustain.
10. Acknowledgments
We thank Rob Wilton, Martin Bjorklund, Mahesh Jethanandani, Lou
Berger, Kent Watsen, Phil Shafer, Ladislav Lhotka, Tim Carey, and
Reshad Rahman for valuable feedback and suggestions.
11. References
11.1. Normative 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>.
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[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010,
<https://www.rfc-editor.org/info/rfc6020>.
[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>.
[RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types",
RFC 6991, DOI 10.17487/RFC6991, July 2013,
<https://www.rfc-editor.org/info/rfc6991>.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016,
<https://www.rfc-editor.org/info/rfc7950>.
[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
<https://www.rfc-editor.org/info/rfc8040>.
[RFC8072] Bierman, A., Bjorklund, M., and K. Watsen, "YANG Patch
Media Type", RFC 8072, DOI 10.17487/RFC8072, February
2017, <https://www.rfc-editor.org/info/rfc8072>.
[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>.
[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>.
[RFC8342] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
and R. Wilton, "Network Management Datastore Architecture
(NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018,
<https://www.rfc-editor.org/info/rfc8342>.
Clemm, et al. Expires February 7, 2022 [Page 17]
Internet-Draft August 2021
[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
[RFC8343] Bjorklund, M., "A YANG Data Model for Interface
Management", RFC 8343, DOI 10.17487/RFC8343, March 2018,
<https://www.rfc-editor.org/info/rfc8343>.
Appendix A. Possible Future Extensions
It is conceivable to extend the compare operation with a number of
possible additional features in the future.
Specifically, it is possible to define an extension with an optional
feature for dampening. This will allow clients to specify a minimum
time period for which a difference must persist for it to be
reported. This will enable clients to distinguish between
differences that are only fleeting from ones that are not and that
may represent a real operational issue and inconsistency within the
device.
For this purpose, an additional input parameter can be added to
specify the dampening period. Only differences that pertain for at
least the dampening time are reported. A value of 0 or omission of
the parameter indicates no dampening. Reporting of differences MAY
correspondingly be delayed by the dampening period from the time the
request is received.
To implement this feature, a server implementation might run a
comparison when the RPC is first invoked and temporarily store the
result. Subsequently, it could wait until after the end of the
dampening period to check whether the same differences are still
observed. The differences that still persist are then returned.
Authors' Addresses
Alexander Clemm
Futurewei
2330 Central Expressway
Santa Clara, CA 95050
USA
Email: ludwig@clemm.org
Clemm, et al. Expires February 7, 2022 [Page 18]
Internet-Draft August 2021
Yingzhen Qu
Futurewei
2330 Central Expressway
Santa Clara, CA 95050
USA
Email: yqu@futurewei.com
Jeff Tantsura
Microsoft
Email: jefftant.ietf@gmail.com
Andy Bierman
YumaWorks
Email: andy@yumaworks.com
Clemm, et al. Expires February 7, 2022 [Page 19]
