| Internet-Draft | Adaptive Subscription | July 2021 |
| Wu, et al. | Expires 11 January 2022 | [Page] |
This document defines a YANG data model and associated mechanism enabling subscriber's adaptive subscriptions to a publisher's event streams with various different period intervals to report updates. Applying these elements allows servers automatically adjust the volume of telemetry traffic and rate of traffic sent from publisher to the receivers.¶
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This Internet-Draft will expire on 11 January 2022.¶
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 the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.¶
YANG-Push subscriptions [RFC8641] allow client applications to subscribe to continuous datastore updates without needing to poll. It defines a mechanism (i.e.,update trigger) to determine when an update record needs to be generated. Two type of subscriptions are introduced in [RFC8641], distinguished by how updates are triggered: periodic and on-change.¶
However in some large scale deployments (e.g., wireless network performance monitoring) where an increased data collection rate is being used, it becomes more likely that a burst of streamed data may temporarily overwhelm a receiver and consume expensive network resource (e.g., radio resource). If the rate at which we can collect a stream of data is set too low or getting low priority telemetry data dropped, these telemetry data are not sufficient to detect and diagnose problems and verify correct network behavior. There is a need for a service to configure both clients and servers with multiple different period intervals and corresponding subscription policy which allows servers/publishers automatically switch to different period intervals according to resource usage change without the interaction with the remote client, e.g., when the wireless signal strength falls below a configured low watermark, the subscribed data can be streamed at a higher rate while when the wireless signal strength crosses a configured high watermark, the subscribed data can be streamed at lower rate.¶
This document defines a YANG data model and associated mechanism enabling subscriber's adaptive subscriptions to a publisher's event streams. Applying these elements allows servers to automatically adjust the volume of telemetry traffic and rate of traffic sent from publisher to the receivers.¶
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 following terms are defined in [RFC5277] [RFC7950] [RFC3198] [RFC8342] [RFC8639] and are not redefined here:¶
This document defines a YANG module "ietf-adaptive-subscription", which augments the "update-trigger" choice defined in the "ietf-yang-push" module [RFC8641] with subscription configuration parameters that are specific to adaptive subscription.¶
In addition to Subscription state notifications defined in [RFC8639] and Notifications for Subscribed Content defined in [RFC8641], "ietf-adaptive-subscription" YANG module also defines "adaptive-period-update" notification to report update interval change.¶
The following tree diagrams [RFC8340] provide an overview of the data model for "ietf-adaptive-subscription.yang" module.¶
module: ietf-adaptive-subscription
augment /sn:subscriptions/sn:subscription/yp:update-trigger:
+--rw (adaptive-subscription)?
+--:(adaptive-subscriptions)
+--rw adaptive-subscriptions
+--rw adaptive-period* [name]
+--rw name string
+--rw xpath-external-eval string
+--rw watermark? uint32
+--rw period centiseconds
+--rw anchor-time? yang:date-and-time
augment /sn:establish-subscription/sn:input/yp:update-trigger:
+-- (adaptive-subscription)?
+--:(adaptive-subscriptions)
+--rw adaptive-subscriptions
+--rw adaptive-period* [name]
+--rw name string
+--rw xpath-external-eval string
+--rw watermark? uint32
+--rw period centiseconds
+--rw anchor-time? yang:date-and-time
notifications:
+---n adaptive-period-update
+--ro id? sn:subscription-id
+--ro period centiseconds
+--ro anchor-time? yang:date-and-time
+--ro (selection-filter)?
+--:(by-reference)
| +--ro selection-filter-ref selection-filter-ref
+--:(within-subscription)
+--ro (filter-spec)?
+--:(datastore-subtree-filter)
| +--ro datastore-subtree-filter? <anydata> {sn:subtree}?
+--:(datastore-xpath-filter)
+--ro datastore-xpath-filter? yang:xpath1.0 {sn:xpath}?¶
For adaptive subscriptions, triggered updates will occur at the boundaries of specified time intervals when a trigger condition is satisfied. These boundaries can be calculated from the adaptive periodic parameters:¶
The augmentation of YANG module ietf-yang-push made to RPCs specified in YANG module ietf-subscribed-notifications [RFC8639] is introduced. This augmentation concerns the "establish- subscription" RPC, which is augmented with parameters that are needed to specify adaptive subscriptions. These parameters are same as one defined in Section 2.1.¶
The adaptive update notification is similar to Subscription state change notifications defined in [RFC8639]. It is inserted into the sequence of notification messages sent to a particular receiver. The adaptive update notification cannot be dropped or filtered out, it cannot be stored in replay buffers, and it is delivered only to impacted receivers of a subscription. The identification of adaptive update notification is easy to separate from other notification messages through the use of the YANG extension "subscription-state-notif". This extension tags a notification as a subscription state change notification.¶
The objects in the 'adpative-update' notification include:¶
<CODE BEGINS> file "ietf-adaptive-subscription@2020-02-14.yang"
module ietf-adaptive-subscription {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-adaptive-subscription";
prefix as;
import ietf-subscribed-notifications {
prefix sn;
}
import ietf-yang-push {
prefix yp;
}
import ietf-yang-types {
prefix yang;
}
organization
"IETF NETCONF (Network Configuration) Working Group";
contact
"";
description
"NETCONF Protocol Data Types and Protocol Operations.
Copyright (c) 2020 IETF Trust and the persons identified as
the document authors. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject
to the license terms contained in, the Simplified BSD License
set forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(http://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC xxxx; see
the RFC itself for full legal notices.";
revision 2019-12-15 {
description
"Initial revision";
reference
"RFCxxx Adaptive subscription to YANG notification.";
}
typedef centiseconds {
type uint32;
description
"A period of time, measured in units of 0.01 seconds.";
}
typedef seconds {
type uint32;
description
"A period of time, measured in units of 1 seconds.";
}
grouping adaptive-subscription-modifiable {
description
"This grouping describes the datastore-specific adaptive subscription
conditions that can be changed during the lifetime of the
subscription.";
choice adaptive-subscription {
description
"Defines necessary conditions for sending an event record to
the subscriber.";
container adaptive-subscriptions {
list adaptive-period {
key "name";
description
"Defines necessary conditions to switch update interval for
sending an event record to the subscriber. The event record output
generation will not be influeced these conditions.";
leaf name {
type string {
length "1..64";
}
description
"The name of the condition to be matched. A device MAY further
restrict the length of this name; space and special
characters are not allowed.";
}
leaf xpath-external-eval {
type string;
description
"A XPath string, representing a logical expression,
which can contain comparisons of datastore values
and logical operations in the XPath format.";
}
leaf watermark {
type uint32;
description
"The watermark for targeted data object. The high
watermark, lowe watermark can be specified for the
targeted data object.";
}
leaf period {
type centiseconds;
mandatory true;
description
"Duration of time that should occur between periodic
push updates, in units of 0.01 seconds.";
}
leaf anchor-time {
type yang:date-and-time;
description
"Designates a timestamp before or after which a series
of periodic push updates are determined. The next
update will take place at a point in time that is a
multiple of a period from the 'anchor-time'.
For example, for an 'anchor-time' that is set for the
top of a particular minute and a period interval of a
minute, updates will be sent at the top of every
minute that this subscription is active.";
}
}
description
"Container for adaptive subscription.";
}
}
}
augment "/sn:subscriptions/sn:subscription/yp:update-trigger" {
description
"This augmentation adds additional subscription parameters
that apply specifically to adaptive subscription.";
uses adaptive-subscription-modifiable;
}
augment "/sn:establish-subscription/sn:input/yp:update-trigger" {
description
"This augmentation adds additional subscription parameters
that apply specifically to datastore updates to RPC input.";
uses adaptive-subscription-modifiable;
}
notification adaptive-period-update {
sn:subscription-state-notification;
description
"This notification contains a push update that in turn contains
data subscribed to via a subscription. In the case of a
periodic subscription, this notification is sent for periodic
updates. It can also be used for synchronization updates of
an on-change subscription. This notification shall only be
sent to receivers of a subscription. It does not constitute
a general-purpose notification that would be subscribable as
part of the NETCONF event stream by any receiver.";
leaf id {
type sn:subscription-id;
description
"This references the subscription that drove the
notification to be sent.";
}
leaf period {
type centiseconds;
mandatory true;
description
"New duration of time that should occur between periodic
push updates, in units of 0.01 seconds.";
}
leaf anchor-time {
type yang:date-and-time;
description
"Designates a timestamp before or after which a series
of periodic push updates are determined. The next
update will take place at a point in time that is a
multiple of a period from the 'anchor-time'.
For example, for an 'anchor-time' that is set for the
top of a particular minute and a period interval of a
minute, updates will be sent at the top of every
minute that this subscription is active.";
}
uses yp:datastore-criteria {
refine "selection-filter/within-subscription" {
description
"Specifies the selection filter and where it originated
from. If the 'selection-filter-ref' is populated, the
filter in the subscription came from the 'filters'
container. Otherwise, it is populated in-line as part
of the subscription itself.";
}
}
}
}
<CODE ENDS>¶
This document registers two URIs in the IETF XML registry [RFC3688]. Following the format in [RFC3688], the following registrations are requested to be made:¶
---------------------------------------------------------------------
URI: urn:ietf:params:xml:ns:yang:ietf-adaptive-subscription
Registrant Contact: The IESG.
XML: N/A, the requested URI is an XML namespace.
---------------------------------------------------------------------¶
This document registers two YANG modules in the YANG Module Names registry [RFC7950]. . Following the format in [RFC6020], the following registration has been made:¶
---------------------------------------------------------------------
Name: ietf-adaptive-subscription
Namespace: urn:ietf:params:xml:ns:yang:ietf-adaptive-subscription
Prefix: as
Reference: RFC xxxx
---------------------------------------------------------------------¶
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 is HTTPS, and the mandatory-to-implement secure transport is TLS [RFC8446].¶
The NETCONF 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 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:¶
Michale Wang, Liang Geng for his major contributions to the initial modeling and use cases.¶
Michale Wang Email: wangzitao@huawei.com Liang Geng China Mobile 32 Xuanwumen West St, Xicheng District Beijing 10053 Email: gengliang@chinamobile.com¶
We would like to thanks Rob Wilton, Thomas Graf, Andy Bierman, Michael Richardson, Henk Birkholz for valuable review on this document, special thanks to Thmas and Michael to organize the discussion on several relevant drafts and reach the common understanding on the concept and ideas. Thanks Michael for providing CHIP/Matter WIFI statistics reference.¶
The example YANG module used in this document represents a Wi-Fi Network Diagnostics data specified in [CHIP] which can be used by a Node to assist a user or Administrative Node in diagnosing potential problems.¶
YANG tree diagram for the "example-wifi-mac" module:¶
module: example-wifi-network-diagnostic
+--rw server
| +--rw bssid? yang:mac-address
| +--rw security-type? enumeration
| +--rw wifi-version? enumeration
| +--rw channel-num? int8
| +--rw rssi? int8
| +--rw beacon-lost-count? int8
| +--rw beacon-rx-count? int8
| +--rw packet-multicast-rx-count? int8
| +--rw packet-multicast-tx-count? int8
| +--rw packet-unicast-rx-count? int8
| +--rw packet-unicast-tx-count? int8
| +--rw current-max-rate? int8
| +--rw overrun-count? int8
+--rw events
+--rw event* [name]
+--rw name string
+--rw disconnection? enumeration
+--rw association-failure? enumeration
+--rw Connection-status? enumeration¶
module example-wifi-network-diagnostic {
yang-version 1;
namespace "http://example.com/yang/wifi-network-diagnostic";
prefix wnd;
import ietf-yang-types {
prefix yang;
}
container server {
description
"Configuration of the WiFi Server logical entity.";
leaf bssid {
type yang:mac-address;
description
"The MAC address of a wireless access point.";
}
leaf security-type {
type enumeration {
enum unspecified {
value 0;
}
enum none {
value 1;
}
enum wep {
value 2;
}
enum wpa {
value 3;
}
enum wpa2 {
value 4;
}
enum wpa3 {
value 5;
}
}
description
"The type of Wi-Fi security used. A value of 0
indicate that the interface is not currently
configured or operational.";
}
leaf wifi-version {
type enumeration {
enum 80211a {
value 0;
}
enum 80211b {
value 1;
}
enum 80211g {
value 2;
}
enum 80211n {
value 3;
}
enum 80211ac {
value 4;
}
enum 80211ax {
value 5;
}
}
description
"The highest 802.11 standard version usable
by the Node.";
}
leaf channel-num {
type int8;
description
"The channel that Wi-Fi communication is currently
operating on. A value of 0indicates that the interface
is not currently configured or operational.";
}
leaf rssi {
type int8;
description
"The RSSI of the Node’s Wi-Fi radio in dBm.";
}
leaf beacon-lost-count {
type int8;
description
"The count of the number of missed beacons the
Node has detected.";
}
leaf beacon-rx-count {
type int8;
description
"The count of the number of received beacons. The
total number of expected beacons that could have been
received during the interval since association SHOULD
match the sum of BeaconRxCount and BeaconLostCount. ";
}
leaf packet-multicast-rx-count {
type int8;
description
"The number of multicast packets received by
the Node.";
}
leaf packet-multicast-tx-count {
type int8;
description
"The number of multicast packets transmitted by
the Node.";
}
leaf packet-unicast-rx-count {
type int8;
description
"The number of multicast packets received by
the Node.";
}
leaf packet-unicast-tx-count {
type int8;
description
"The number of multicast packets transmitted by
the Node.";
}
leaf current-max-rate {
type int8;
description
"The current maximum PHY rate of transfer of
data in bytes-per-second.";
}
leaf overrun-count {
type int8;
description
"The number of packets dropped either at ingress or
egress, due to lack of buffer memory to retain all
packets on the ethernet network interface. The
OverrunCount attribute SHALL be reset to 0 upon a
reboot of the Node..";
}
}
container events {
description
"Configuration of WIFI Network Diagnostic events.";
list event {
key "name";
description
"The list of event sources configured on the
server.";
leaf name {
type string;
description
"The unique name of an event source.";
}
leaf disconnection {
type enumeration {
enum de-authenticated {
value 1;
}
enum dis-association {
value 2;
}
}
description
"A Node’s Wi-Fi connection has been disconnected as a
result of de-authenticated or dis-association and
indicates the reason.";
}
leaf association-failure {
type enumeration {
enum unknown {
value 0;
}
enum association-failed {
value 1;
}
enum authentication-failed {
value 2;
}
enum ssid-not-found {
value 3;
}
}
description
"A Node has attempted to connect, or reconnect, to
a Wi-Fi access point, but is unable to successfully
associate or authenticate, after exhausting all
internal retries of its supplicant.";
}
leaf Connection-status {
type enumeration {
enum connected {
value 1;
}
enum notconnected {
value 2;
}
}
description
"A Node’s connection status to a Wi-Fi network has
changed. Connected, in this context, SHALL mean that
a Node acting as a Wi-Fi station is successfully
associated to a Wi-Fi Access Point..";
}
}
}
}
¶
The examples within this document use the normative YANG module "ietf-adaptive-subscription" as defined in Section 3 and the non-normative example YANG module "example-wifi-network-diagnostic" as defined in Appendix A.1.¶
This section shows some typical adaptive subscription and notification message exchanges.¶
The client configures adaptive subscription policy parameters on the server. The adaptive subscription configuration parameters require the server to support two update intervals (i.e., 5 seconds, 60 seconds) and scan all clients every 60 seconds in the sampling window if the rssi value of client is greater than or equal to -65dB in the sampling window; If the rssi value of client is less than -65dB, switch to 5 seconds period value, and then scan all clients every 60 seconds.¶
<rpc message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<edit-config>
<target>
<running/>
</target>
<config
xmlns:xc="urn:ietf:params:xml:ns:netconf:base:1.0">
<top
xmlns="http://example.com/schema/1.2/config"
xmlns:yp="urn:ietf:params:xml:ns:yang:ietf-yang-push">
<yp:datastore
xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores">
ds:running
</yp:datastore>
<yp:datastore-xpath-filter
xmlns:wnd="https://example.com/sample-data/1.0">
/wnd:example-wifi-network-diagnostic
</yp:datastore-xpath-filter>
<as:adaptive-subscriptions
xmlns:as="urn:ietf:params:xml:ns:yang:ietf-adaptive-subscription">
<as:adaptive-period>
<as:xpath-external-eval>
/wnd:server[rssi < -65]
</as:xpath-external-eval>
<as:watermark>-65</as:watermark>
<as:period>5</as:period>
</as:adaptive-period>
<as:adaptive-period>
<as:xpath-external-eval>
/wnd:server[rssi ≥ -65]
</as:xpath-external-eval>
<as:watermark>-65</as:watermark>
<as:period>60</as:period>
</as:adaptive-period>
</as:adaptive-subscriptions>
</top>
</config>
</edit-config>
</rpc>¶
The subscriber sends an "establish-subscription" RPC with the parameters listed in to request the creation of a adaptive subscription. The adaptive subscription configuration parameters require the server to scan all clients every 5 seconds if the rssi value of client is less than -65dB; If the rssi value of client is great than or equal to -65dB, switch to 60 seconds period value, and then report all clients every 60 seconds or scan every 5 seconds, collect 12 measurement values but report the last measurement value or average value of 12 measurement values. (Section 2)¶
<netconf:rpc message-id="101"
xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
<establish-subscription
xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications"
xmlns:yp="urn:ietf:params:xml:ns:yang:ietf-yang-push">
<yp:datastore
xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores">
ds:running
</yp:datastore>
<yp:datastore-xpath-filter
xmlns:wnd="https://example.com/sample-data/1.0">
/wnd:example-wifi-network-diagnostic
</yp:datastore-xpath-filter>
<as:adaptive-subscriptions
xmlns:as="urn:ietf:params:xml:ns:yang:ietf-adaptive-subscription">
<as:adaptive-period>
<as:xpath-external-eval>wnd:server[rssi < -65]
</as:xpath-external-eval>
<as:watermark>-65</as:watermark>
<as:period>5</as:period>
</as:adaptive-period>
<as:adaptive-period>
<as:xpath-external-eval>wnd:server[rssi ≥ -65]
</as:xpath-external-eval>
<as:watermark>-65</as:watermark>
<as:period>60</as:period>
</as:adaptive-period>
</as:adaptive-subscriptions>
</establish-subscription>
</netconf:rpc>¶
In another example, the adaptive subscription configuration parameters could also require the server to scan all clients every 5 seconds and report if the difference between maximum value of client rssi and minimum value of client rssi is greater than 0.20 dB in the sampling window; If the difference between maximum value of client rssi and minimum value of client rssi is less than 0.20 dB, switch to 60 seconds period value and then scan all clients every 60 seconds and report the last measurement value. If the difference between maximum value of client rssi and minimum value of client rssi is greater than or equal to 0.20 dB in two consecutive sampling windows, then in the second sampling window, only report the measurement value not reported by the previous sampling window.¶
<netconf:rpc message-id="101"
xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
<establish-subscription
xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications"
xmlns:yp="urn:ietf:params:xml:ns:yang:ietf-yang-push">
<yp:datastore
xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores">
ds:running
</yp:datastore>
<yp:datastore-xpath-filter
xmlns:wnd="https://example.com/sample-data/1.0">
/wnd:example-wifi-network-dianostic
</yp:datastore-xpath-filter>
<as:adaptive-subscriptions
xmlns:as="urn:ietf:params:xml:ns:yang:ietf-adaptive-subscription">
<as:adaptive-period>
<as:xpath-external-eval>
wnd:server[max(rssi)-min(rssi) ≥ 20]
</as:xpath-external-eval>
<as:watermark>20</as:watermark>
<as:period>5</as:period>
</as:adaptive-period>
<as:adaptive-period>
<as:xpath-external-eval>
wnd:server[max(rssi)-min(rssi) < 20]
</as:xpath-external-eval>
<as:watermark>20</as:watermark>
<as:period>60</as:period>
</as:adaptive-period>
</as:adaptive-subscriptions>
</establish-subscription>
</netconf:rpc>¶
Upon the server switches to from the update interval 5 seconds to the new update interval 60 seconds, Before sending event records to receivers, the "adaptive-update" notification should be generated and sent to the receivers to inform the receivers that the update interval value is switched to the new value.¶
<notification
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0"
xmlns:yp="urn:ietf:params:xml:ns:yang:ietf-yang-push">
<eventTime>2016-11-21T13:51:00Z</eventTime>
<adaptive-update
xmlns="http://example.com/ietf-adaptive-subscription">
<id>0</id>
<period>60</period>
<yp:datastore
xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores">
ds:running
</yp:datastore>
<yp:datastore-xpath-filter
xmlns:ex="https://example.com/sample-data/1.0">
/ex:example-wifi-network-diagnostic
</yp:datastore-xpath-filter>
</adaptive-update>
</notification>¶
v05 -v06¶
v04 -v05¶
v03 - v04¶
v02 - v03¶