| NETMOD Working Group | A. Bierman |
| Internet-Draft | YumaWorks |
| Intended status: Standards Track | Q. Wu |
| Expires: January 13, 2021 | Huawei |
| I. Bryskin | |
| Individual | |
| H. Birkholz | |
| Fraunhofer SIT | |
| X. Liu | |
| Volta Networks | |
| B. Claise | |
| Cisco | |
| July 12, 2020 |
A YANG Data model for ECA Policy Management
draft-wwx-netmod-event-yang-08
This document defines a YANG data model for the Event Condition Action (ECA) policy management. The ECA policy YANG provides the ability to delegate the network management function to the server and control the configuration and monitor state change and take simple and instant action on the server when a trigger condition on the system state is met.
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 January 13, 2021.
Copyright (c) 2020 IETF Trust and the persons identified as the document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.
Traditional approaches for network to automatically perform corrective actions in response to network events have been largely built on centralized policy based management [RFC3198]. With centralized network mangement, the managed object state or operational state spanning across the devices needs to be retrieved by the client from various different servers. However there are issues associated with centrallized network management:
A more effective alternative to centralized network management is to delegate network management function to servers in the network and allow each server monitor state changes of managed objects. Accordingly there is a need for a service to provide continuous peformance monitoring and detect defects and failures and take corrective action.
This document defines a ECA Policy management YANG data model. The ECA Policy YANG provides the ability to move the network management task to the server for self monitoring and self healing and control the configurations and monitor state parameters and take simple and instant action on the server when a trigger condition on the system state is met.
The data model in this document is designed to be compliant with the Network Management Datastore Architecture (NMDA) [RFC8342].
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. In this document, these words will appear with that interpretation only when in ALL CAPS. Lower case uses of these words are not to be interpreted as carrying [RFC2119] significance.
The following terms are defined in [RFC7950] [RFC3460] and are not redefined here:
This document uses the following terms:
Tree diagrams used in this document follow the notation defined in [RFC8340].
A ECA policy rule is read as: when event occurs in a situation where condition is true, then action is executed. Therefore ECA comprises three key elements: event, associated conditions, and actions. These three elements should be pushed down and configured on the server by the client. If the action is rejected by the server duing ECA policy execution, the action should be rolled back and cleaned up.
ECA policy variable (PV) generically represents datastore states that change (or "vary"), and that is set or evaluated by software. The value of ECA policy variable is used for modeling values and constants used in policy conditions and actions. In policy, conditions and actions can abstract information as "policy variables" to be evaluated in logical expressions, or set by actions, e.g., the policy condition has the semantics "variable matches value" while policy action has the semantics "set variable to value".
In ECA, two type of policy variables are defined, pv-source variable and pv-result variable. pv-source variable represents an XPath result, which contains one of four data types: Boolean, Number, String, and Node Set while pv-result variable represents the value of the result of an Policy Variable evaluation.
Each ECA policy variable has the following two attributes:
The following operations are allowed with/on a PV:
PVs could also be a source of information sent to the client in notification messages.
PVs could be also used in condition expressions.
+--rw policy-variables
| +--rw policy-variable* [name]
| +--rw name string
| +--rw (xpath-value-choice)?
| +--:(policy-source)
| | +--rw (pv-source)
| | +--:(xpath-expr)
| | | +--rw xpath-expr? yang:xpath1.0
| | +--:(scalar-constant)
| | | +--rw scalar-constant? string
| | +--:(nodeset-constant)
| | +--rw nodeset-constant? <anydata>
| +--:(policy-result)
| +--rw (pv-result)
| +--:(scalar-value)
| | +--rw scalar-value? string
| +--:(nodeset-value)
| +--rw nodeset-value? <anydata>
The model structure for the Policy Variable is shown below:
The ECA Event is any subscribable event notification either explicitly defined in a YANG module (e.g., interface management model) supported by the server or a event stream conveyed to the server via YANG Push subscription. The ECA event are used to keep track of state of changes associated with one of multiple operational state data objects in the network device.
Each ECA Event has the following attributes:
A client may define an event of interest by making use of YANG PUSH subscription. Specifically, the client may configure an ECA event according to the ECA model specifying the event's name, as well as the name of corresponding PUSH subscrition. In this case, the server is expected to:
All events (specified in at least one ECA pushed to the server) are required to be constantly monitored by the server. One way to think of this is that the server subscribes to its own publications with respect to all events that are associated with at least one ECA.
The model structure for the ECA Event is shown below:
+--rw events
| +--rw event* [event-name]
| +--rw event-name string
| +--rw event-type? identityref
| +--rw policy-variable* -> /gncd/policy-variables/policy-variable/name
| +--rw local-policy-variable* -> /gncd/ecas/eca/policy-variable/name
| +--rw (type-choice)?
| +--:(server-event)
| | +--rw event-stream? string
| | +--rw event-module? string
| | +--rw event? <anydata>
| +--:(datastore-event)
| | +--rw datatore? string
| | +--rw data-path? string
| | +--rw data? <anydata>
| +--:(timer-event)
| | +--rw time-schedule!
| | +--rw period? centiseconds
| | +--rw count? uint16
| +--:(diagnostics-event)
The ECA Condition is the logical expression that is specified in a form of Xpath expression and evaluated to TRUE or FALSE. The XPath expression specifies an arbitrary logical/mathematical expression; The elements of the ECA Condition expression are referred by the XPaths pointing to referred datastore states.
The ECA Condition expression in the form of XPath expression allows for specifying a condition of arbitrary complexity as a single string with an XPath expression, in which pertinent PVs and datastore states are referred to by their respective positions in the YANG tree.
ECA Conditions are associated with ECA Events and evaluated only within event threads triggered by the event detection.
When an ECA Condition is evaluated to TRUE, the associated ECA Action is executed.
+--rw conditions
| +--rw condition* [name]
| +--rw name string
| +--rw (expression-choice)?
| +--:(xpath)
| +--rw condition-xpath? string
The model structure for the condition is shown below:
Example: "/test1[name=$badfan] and /test2[name=$badfan]"
The same value of 'badfan' is expected in each instance.
[TBD: Need to determine what XPath parsers support.
Need to support simple expressions like
PV(x) = $A
PV(x) = $A + $B
May need to wrapper in function calls
PV(x) = number($A)
PV(x) = number($A) + number($B)
TBD: How to do conditional assignments
if nmda-supported()
PV(top) = /interfaces
else
PV(top) = /interfaces-state
end
Then an XPath expression can use
$top/interface/name
Policy variables are mapped to XPath variable bindings so they can be referenced in the XPath expression for a Condition.
All XPath expressions used in ECA share the following XPath context definition.
Not all errors can be detected at configuration time. Error that occur while ECA logis is being evaluated will cause the server to generate an eca-exception notification.
TBD: Does an exception cause the ECA entry to be disabled automatically?
identity eca-exception-reason {
description
"Base of all values for the 'reason' leaf in the
eca-exception notification.";
}
identity varbind-unknown {
base eca-exception-reason;
description
"The requested policy variable binding is not defined.
The variable binding cannot be resolved in the XPath
evaluation.";
}
// TBD: define exceptions as needed
notification eca-exception {
description
"This notification is sent when some error occurs
while the server is processing ECA logic.
[TBD: lots more detail and parameters]";
leaf reason {
type eca-exception-reason;
}
}
The ECA Action list consists of updates or invocations on local managed object attributes and a set of actions are defined as follows, which will be performed when the corresponding event is triggered:
Three points are worth noting:
+--rw actions
| +--rw action* [name]
| +--rw name string
| +--rw action-element* [name]
| | +--rw name string
| | +--rw action-type? identityref
| | +--rw (action-operation)?
| | +--:(notify-operation)
| | +--rw notify-operation
| | +--rw name? string
| | +--rw policy-variable* [name]
| | +--rw name string
| +--rw time-schedule!
| | +--rw period? centiseconds
| | +--rw count? uint16
The model structure for the actions is shown below:
An ECA container includes:
TBD: how different ECAs do not impact each other if they share PVs and other components is not in the scope of this document at this moment.
A set of common event PVs need to be set for every invocation of condition or action logic:
$event-type (string)
$event-name (string)
For event-type = "server-event"
$event-stream (string)
$event-module (string)
$event-name (string)
$event (node-set)
The condition can use these PVs directly in an expression
An expression can access client-configured PVs of course
$event/child[name=$some-global-var] > 10
For event-type = "datastore"
$datastore (string)
$data-path (string)
$data (node-set)
The data is defined to be a container with the requested data as child nodes
$data/interface[type=$gigabit-eth] // (node-set is an array of data nodes, usually siblings)
A standard sustained-event func call should be defined to specify how many seconds the
XPath expression needs to be true to consider the function result true
// check every 5 seconds up to 60 seconds
sustained-event("$event/child[name=$some-global-var] > 10", 5, 12)
function boolean sustained-event (string expr, number interval, number count)
test expression 'expr' once per 'interval'. Keep testing once per interval until
false result reached or 'count' number of interval on specific interface has been
tested true.Return true if condition tested true for count intervals; Returns
false otherwise
The ECA XPath function library is expected to grow over time and additional standard or vendor function libraries should be possible. The server should provide a read-only leaf-list of ECA function libraries supported.
TBD: How can ECA access specific datastores? Currently no NMDA support for config=true values in <operational> is provided. Access to <candidate> datastore is not possible.
module: ietf-eca
+--rw gncd
+--rw policy-variables
| +--rw policy-variable* [name]
| +--rw name string
| +--rw (xpath-value-choice)?
| +--:(policy-source)
| | +--rw (pv-source)
| | +--:(xpath-expr)
| | | +--rw xpath-expr? yang:xpath1.0
| | +--:(scalar-constant)
| | | +--rw scalar-constant? string
| | +--:(nodeset-constant)
| | +--rw nodeset-constant? <anydata>
| +--:(policy-result)
| +--rw (pv-result)
| +--:(scalar-value)
| | +--rw scalar-value? string
| +--:(nodeset-value)
| +--rw nodeset-value? <anydata>
+--rw events
| +--rw event* [event-name]
| +--rw event-name string
| +--rw event-type? identityref
| +--rw policy-variable* -> /gncd/policy-variables/policy-variable/name
| +--rw local-policy-variable* -> /gncd/ecas/eca/policy-variable/name
| +--rw (type-choice)?
| +--:(server-event)
| | +--rw event-stream? string
| | +--rw event-module? string
| | +--rw event? <anydata>
| +--:(datastore-event)
| | +--rw datatore? string
| | +--rw data-path? string
| | +--rw data? <anydata>
| +--:(timer-event)
| | +--rw time-schedule!
| | +--rw period? centiseconds
| | +--rw count? uint16
| +--:(diagnostics-event)
+--rw conditions
| +--rw condition* [name]
| +--rw name string
| +--rw (expression-choice)?
| +--:(xpath)
| +--rw condition-xpath? string
+--rw actions
| +--rw action* [name]
| +--rw name string
| +--rw action-element* [name]
| | +--rw name string
| | +--rw action-type? identityref
| | +--rw (action-operation)?
| | +--:(notify-operation)
| | +--rw notify-operation
| | +--rw name? string
| | +--rw policy-variable* [name]
| | +--rw name string
| +--rw time-schedule!
| | +--rw period? centiseconds
| | +--rw count? uint16
+--rw ecas
+--rw eca* [name]
+--rw name string
+--rw username string
+--rw event-name string
+--rw policy-variable* [name]
| +--rw name string
| +--rw (xpath-value-choice)?
| | +--:(policy-source)
| | | +--rw (pv-source)
| | | +--:(xpath-expr)
| | | | +--rw xpath-expr? yang:xpath1.0
| | | +--:(scalar-constant)
| | | | +--rw scalar-constant? string
| | | +--:(nodeset-constant)
| | | +--rw nodeset-constant? <anydata>
| | +--:(policy-result)
| | +--rw (pv-result)
| | +--:(scalar-value)
| | | +--rw scalar-value? string
| | +--:(nodeset-value)
| | +--rw nodeset-value? <anydata>
| +--rw is-static? boolean
+--rw condition-action* [name]
| +--rw name string
| +--rw condition? -> /gncd/conditions/condition/name
| +--rw action? -> /gncd/actions/action/name
+---x start
+---x stop
+---x next-action
notifications:
+---n eca-exception
+--ro reason? identityref
The following tree diagrams [RFC8340] provide an overview of the data model for the "ietf-eca" module.
<CODE BEGINS> file "ietf-eca@2019-10-28.yang"
module ietf-eca {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-eca";
prefix gnca;
import ietf-yang-types {
prefix yang;
}
import ietf-netconf-acm {
prefix nacm;
reference
"RFC8341: Network Configuration Access Control Model";
}
organization
"IETF Network Configuration (NETCONF) Working Group";
contact
"WG Web: <http://tools.ietf.org/wg/netmod/>
WG List: <mailto:netmod@ietf.org>
Editor: Qin Wu
<mailto:bill.wu@huawei.com>
Editor: Igor Bryskin
<mailto:Igor.Bryskin@huawei.com>
Editor: Henk Birkholz
<mailto:henk.birkholz@sit.fraunhofer.de>
Editor: Xufeng Liu
<mailto:xufeng.liu.ietf@gmail.com>
Editor: Benoit Claise
<mailto:bclaise@cisco.com>
Editor: Andy Bierman
<mailto:andy@yumaworks.com>
Editor: Alexander Clemm
<mailto:ludwig@clemm.org>";
description
"Event Condition Action (ECA) model.";
revision 2018-06-22 {
description
"Initial revision";
reference
"RFC XXXX";
}
identity argument-type {
description
"Possible values are:
constant, variable, or datastore state.";
}
identity comparison-type {
description
"Possible values are:
equal, not-equal, greater, greater-equal, less, less-equal.";
}
identity logical-operation-type {
description
"Possible values are:
not, or, and.";
}
identity function-type {
description
"Possible values are:
plus, minus, mult, divide, sustained-event.";
}
identity sustained-event {
description
"Identity for standard sustained-event function call,
the input variables for sustained-event include string
expr, number interval, number count. Keep testing
expression 'expr'once per interval until false result
reached or 'count' number of interval on specific interface
has been tested true.Return true if condition tested true
for count intervals; Returns false otherwise.";
}
identity plus {
description
"Identity for standard plus function call, the input
variables for plus function call include src policy argument
and dst policy arugment.";
}
identity mius {
description
"Identity for standard minus function call, the input
variables for plus function call include src policy argument
and dst policy arugment.";
}
identity multiply {
description
"Identity for standard multiply function call, the input
variables for multiply function call include src policy argument
and dst policy arugment.";
}
identity divide {
description
"Identity for standard divide function call, the input
variables for multiply function call include src policy argument
and dst policy arugment.";
}
identity content-moving-operation-type {
description
"Possible values are:
copy, iterate, insert.";
}
identity action-type {
description
"Possible values are:
action, content-move, function-call, rpc, notify.";
}
identity policy-variable-type {
description
"Possible values are:
boolean, int32, int64, uint32, uint64, string, etc.";
}
identity event-type {
description
"Base identity for Event Type.";
}
identity server-event {
base event-type;
description
"Identity for server event.";
}
identity datastore-event {
base event-type;
description
"Identity for datastore event.";
}
identity timer-event {
base event-type;
description
"Identity for timer event.";
}
identity diagnostics-event {
base event-type;
description
"Identity for diagnostics event.";
}
identity eca-exception-reason {
description
"Base of all values for the 'reason' leaf in the
eca-exception notification.";
}
identity varbind-unknown {
base eca-exception-reason;
description
"The requested policy variable binding is not defined.
The variable binding cannot be resolved in the XPath
evaluation.";
}
typedef centiseconds {
type uint32;
description
"A period of time, measured in units of 0.01 seconds.";
}
typedef oper-status {
type enumeration {
enum completed {
description
"Completed with no error.";
}
enum running {
description
"Currently with no error.";
}
enum sleeping {
description
"Sleeping because of time schedule.";
}
enum stoped {
description
"Stopped by the operator.";
}
enum failed {
description
"Failed with errors.";
}
enum error-handling {
description
"Asking the operator to handle an error.";
}
}
description
"The operational status of an ECA execution.";
}
grouping scalar-value {
leaf scalar-value {
type string;
description
"Represents an XPath simple value that has an
XPath type of Boolean, String, or Number.
This value will be converted to an XPath type,
as needed.
A YANG value is encoded as a string using the same
rules as the 'default' value for the data type.
An eca-exception notification is generated if a scalar
XPath value is used in a path expression, where a
node-set is expected. Normally XPath will treat this result
as an empty node-set, but this is an ECA programming error.";
}
}
grouping nodeset-value {
anydata nodeset-value {
description
"Represents an XPath node set. A 'node-set' anydata node
with no child data nodes represents an empty node-set.
Each child node in within this anydata structure
represents a subtree that is present in the XPath
node-set.
An XPath node-set is not required to contain a top-level
YANG data node. It is not required to contain an entire
complete subtree.
It is am implementation-specific manner how a
representation of YANG 'anydata' nodes are mapped
to specific YANG module schema definitions.";
}
}
grouping scalar-constant {
leaf scalar-constant {
type string;
description
"Represents an XPath simple value that has an
XPath type of Boolean, String, or Number.
This value will be converted to an XPath type,
as needed.
A YANG value is encoded as a string using the same
rules as the 'default' value for the data type.
An eca-exception notification is generated if a scalar
XPath value is used in a path expression, where a
node-set is expected. Normally XPath will treat this result
as an empty node-set, but this is an ECA programming error.";
}
}
grouping nodeset-constant {
anydata nodeset-constant {
description
"Represents an XPath node set. A 'node-set' anydata node
with no child data nodes represents an empty node-set.
Each child node in within this anydata structure
represents a subtree that is present in the XPath
node-set.
An XPath node-set is not required to contain a top-level
YANG data node. It is not required to contain an entire
complete subtree.
It is am implementation-specific manner how a
representation of YANG 'anydata' nodes are mapped
to specific YANG module schema definitions.";
}
}
grouping pv-source {
choice pv-source {
mandatory true;
description
"A PV source represents an XPath result, which contains
one of four data types: Boolean, Number, String,
and Node Set. XPath defines mechanisms to covert
values between these four types.
The 'xpath-expr' leaf is used to assign the PV source
to the result of an arbitrary XPath expression.
The result of this expression evaluation is used
internally as needed. The result may be any one of
the XPath data types.
The 'scalar-constant' leaf is used to represent a Boolean,
String, or Number XPath constant value.
The 'nodeset-constant' anydata structure is used to
represent a constant XPath node-set.";
leaf xpath-expr {
type yang:xpath1.0;
description
"Contains an XPath expression that must be evaluated
to produce an XPath value. [section X.X] describes
the XPath execution environment used to process this
object.";
}
case scalar-constant {
uses scalar-constant;
}
case nodeset-constant {
uses nodeset-constant;
}
}
}
grouping pv-result {
choice pv-result {
mandatory true;
description
"Represents the value of the result of an
Policy Variable evaluation.
The 'scalar-value' leaf is used to represent a Boolean,
String, or Number XPath result value.
The 'nodeset-value' anydata structure is used to represent
an XPath node-set result.";
case scalar-value {
uses scalar-value;
}
case nodeset-value {
uses nodeset-value;
}
}
}
grouping policy-variable-attributes {
description
"Defining the policy variable attributes, including name, type
and value. These attributes are used as part of the Policy
Variable (PV) definition.";
leaf name {
type string;
description
"A string to uniquely identify a Policy Variable (PV), either
globally for a global PV, or within the scope of ECA for a
local PV.";
}
choice xpath-value-choice {
description
"The type of a policy variable may be either a common
primative type like boolean or a type from existing
schema node referenced by an XPath string.";
case policy-source {
uses pv-source;
}
case policy-result {
uses pv-result;
}
}
}
grouping action-element-attributes {
description
"Grouping of action element attributes.";
leaf action-type {
type identityref {
base action-type;
}
description
"Identifies the action type.";
}
choice action-operation {
description
"The operation choices that an ECA Action can take.";
case notify-operation {
container notify-operation {
description
"The operation is to send a YANG notification.";
leaf name {
type string;
description
"Name of the subscribed YANG notification.";
}
list policy-variable {
key "name";
description
"A list of policy arguments carried in the notification
message.";
leaf name {
type string;
description
"A string name used as the list key to form a list
of policy arguments.";
}
}
}
}
}
}
grouping time-schedule-container {
description
"Grouping to define a container of a time schedule.";
container time-schedule {
presence "Presence indicates that the timer is enabled.";
description
"Specifying the time schedule to execute an ECA Action, or
trigger an event.";
leaf period {
type centiseconds;
description
"Duration of time that should occur between periodic
push updates, in units of 0.01 seconds.";
}
leaf count {
type uint16;
description
"specify the count number of interval that has to pass before
successive adaptive periodic push update records for the same
subscription are generated for a receiver.";
}
}
}
container gncd {
nacm:default-deny-all;
description
"Top level container for Generalized Network Control Automation
(gncd).";
container policy-variables {
description
"Container of global Policy Variables (PVs).";
list policy-variable {
key "name";
description
"A list of global Policy Variables (PVs), with a string
name as the entry key.";
uses policy-variable-attributes;
}
}
container events {
description
"Container of ECA events.";
list event {
key "event-name";
description
"A list of events used as the triggers of ECAs.";
leaf event-name {
type string;
description
"The name of the event.";
}
leaf event-type {
type identityref {
base event-type;
}
description
"The type of the event.";
}
leaf-list policy-variable {
type leafref {
path "/gncd/policy-variables/policy-variable/name";
}
description
"global policy variables, which
are shared by all ECA scripts.";
}
leaf-list local-policy-variable {
type leafref {
path "/gncd/ecas/eca/policy-variable/name";
}
description
"local policy variables, which
are kept within an ECA instance, and appears/
disappears with start/stop of the ECA execution.";
}
choice type-choice {
description
"The type of an event, including server event and datastore event.";
case server-event {
leaf event-stream {
type string;
description
"The name of a subscribed stream .";
}
leaf event-module {
type string;
description
"The name of YANG data module associated with the subscribed
stream.";
}
anydata event {
description
"This anydata value MUST Contain the absolute XPath
expression identifying the element path to the node that is
associated with subscribed stream.";
}
}
case datastore-event {
leaf datatore {
type string;
description
"The name of a datatore from which applications
subscribe to updates.";
}
leaf data-path {
type string;
description
"The absolute XPath expression identifying the
element path to the node that is associated with
subscribed stream..";
}
anydata data {
description
"This anydata value MUST Contain the node that is
associated with the data path.";
}
}
case timer-event {
uses time-schedule-container {
description
"Specifying the time schedule to trigger the event.
If not specified, the event is not triggered.";
}
}
case diagnostics-event;
}
}
}
container conditions {
description
"Container of ECA Conditions.";
list condition {
key "name";
description
"A list of ECA Conditions.";
leaf name {
type string;
description
"A string name to uniquely identify an ECA Condition
globally.";
}
choice expression-choice {
description
"The choices of expression format to specify a condition,
which can be either a XPath string.";
case xpath {
leaf condition-xpath {
type string;
description
"A XPath string, representing a logical expression,
which can contain comparisons of datastore values
and logical operations in the XPath format.";
}
}
}
}
}
container actions {
description
"Container of ECA Actions.";
list action {
key "name";
description
"A list of ECA Actions.";
leaf name {
type string;
description
"A string name to uniquely identify an ECA Action
globally.";
}
list action-element {
key "name";
description
"A list of elements contained in an ECA Action. ";
leaf name {
type string;
description
"A string name to uniquely identify the action element
within the scope of an ECA action.";
}
uses action-element-attributes;
}
uses time-schedule-container {
description
"Specifying the time schedule to execute this ECA
Action.
If not specified, the ECA Action is executed immediately
when it is called.";
}
}
}
container ecas {
description
"Container of ECAs.";
list eca {
key "name";
description
"A list of ECAs";
leaf name {
type string;
description
"A string name to uniquely identify an ECA globally.";
}
leaf username {
type string;
mandatory true;
description
"Name of the user for the session.";
}
leaf event-name {
type string;
mandatory true;
description
"The name of an event that triggers the execution of
this ECA.";
}
list policy-variable {
key "name";
description
"A list of ECA local Policy Variables (PVs), with a
string name as the entry key.";
uses policy-variable-attributes;
leaf is-static {
type boolean;
description
"'true' if the PV is static; 'false' if the PV is
dynamic.
A dynamic PV appears/disappears with the start/stop
of the ECA execution; a static PV exists as long as
the ECA is configured.";
}
}
list condition-action {
key "name";
ordered-by user;
description
"A list of Condition-Actions, which are configured
conditions each with associated actions to be executed
if the condition is evaluated to TRUE.
[TBD Does the server do all the actions where the condition
is true? Does it stop after one condition-action is
completed? How is it possible to require multiple conditions
to be true in order to do 1 action? How will conditions be
reusable and not giant cut-and-paste combination of other
entries?]";
leaf name {
type string;
description
"A string name uniquely identify a Condition-Action
within this ECA.";
}
leaf condition {
type leafref {
path "/gncd/conditions/condition/name";
}
description
"The reference to a configured condition.";
}
leaf action {
type leafref {
path "/gncd/actions/action/name";
}
description
"The reference to a configured action.";
}
}
action start {
description
"Start to execute this ECA.";
}
action stop {
description
"Stop the execution of this ECA.";
}
action next-action {
description
"Resume the execution of this ECA to complete the next
action.";
}
}
}
}
notification eca-exception {
description
"This notification is sent when some error occurs
while the server is processing ECA logic.
[TBD: lots more detail and parameters]";
leaf reason {
type identityref {
base eca-exception-reason;
}
}
}
}
<CODE ENDS>
The YANG modules defined in this document MAY be accessed via the RESTCONF protocol [RFC8040] or NETCONF protocol ([RFC6241]). The lowest RESTCONF or NETCONF layer requires that the transport-layer protocol provides both data integrity and confidentiality, see Section 2 in [RFC8040] and [RFC6241]. 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 [RFC5246].
The NETCONF access control model [RFC6536] 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:
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-eca Registrant Contact: The IESG. XML: N/A, the requested URI is an XML namespace. ---------------------------------------------------------------------
This document registers one YANG module in the YANG Module Names registry [RFC6020].
--------------------------------------------------------------------- Name: ietf-eca Namespace: urn:ietf:params:xml:ns:yang:ietf-eca Prefix: gnca Reference: RFC xxxx ---------------------------------------------------------------------
Igor Bryskin, Xufeng Liu, Alexander Clemm, Henk Birkholz, Tianran Zhou contributed to an earlier version of [GNCA]. We would like to thank the authors of that document on event response behaviors delegation for material that assisted in thinking that helped improve this document.
Alexander Clemm Futurewei Email: ludwig@clemm.org Michale Wang Huawei Email:wangzitao@huawei.com Chongfeng Xie China Telecom Email: xiechf@ctbri.com.cn Xiaopeng Qin Huawei Huawei Bld., No.156 Beiqing Rd. Beijing 100095 China qinxiaopeng@huawei.com Tianran Zhou Huawei Email: zhoutianran@huawei.com Aihua Guo Individual aihguo1@gmail.com Nicola Sambo Scuola Superiore Sant'Anna Via Moruzzi 1 Pisa 56124 Italy Email: nicola.sambo@sssup.it Giuseppe Fioccola Huawei Technologies Riesstrasse, 25 Munich 80992 Germany Email: giuseppe.fioccola@huawei.com
| [RFC5246] | Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) Protocol Version 1.2", RFC 5246, DOI 10.17487/RFC5246, August 2008. |
| [RFC8040] | Bierman, A., Bjorklund, M. and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017. |
| [RFC8340] | Bjorklund, M. and L. Berger, "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018. |
| [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. |
Here are two examples of Condition Expression:
TE metric of Link L in Topology T greater than 100, it can be expressed as follows: "/nw:networks/nw:network[network-id='T']/nt:link[link-id='L']/tet:te\ /tet:te-link-attributes/tet:te-delay-metric > 100"
(a) a condition that only includes data store states and constants, for example:
Allocated bandwidth of Link L in Topology T greater than 75% of what is stored in Policy Variable B, it can be expressed as follows: "/nw:networks/nw:network[network-id='T']/nt:link[link-id='L']/tet:te\ /tet:te-link-attributes/tet:max-resv-link-bandwidth\ > (ietf-eca:policy-variables/policy-variable[name='B']/value) * 0.75"
(b) a condition that also includes a Policy Variable, for example:
+---------------------------+
| Management System |
+---------------------------+
|
ECA |
Model |
|
V
+----------------------^-----+
| Managed Device | |
| | |
| //--\\ Condition--+ |
| | Event| / \ |
| | |----->|Actions |
| \\--// \ / |
| ---- |
+----------------------------+
The management system designs a new ECA policy based on monitored objects in ietf-interfaces module that support threshold checking and pushes down the ECA policy to control interface behavior in the managed device that supports NETCONF/RESTCONF protocol operation, i.e.,scan all interfaces for a certain type every 5 seconds up to 60 seconds and check the counters or status, return an array of interface entries (XPath node-set) that match the search. The XML example snippet is shown as below:
<gnca>
<policy-variables>
<policy-variable>
<name>event-name</name>
<scalar-constant>interface-self-monitoring</scalar-constant>
</policy-variable>
<policy-variable>
<name>event-type</name>
<scalar-constant>server-event</scalar-constant>
</policy-variable>
<policy-variable>
<name>event-stream</name>
<scalar-constant>NETCONF</scalar-constant>
</policy-variable>
<policy-variable>
<name>event-module</name>
<scalar-constant>ietf-interfacs</scalar-constant>
</policy-variable>
<policy-variable>
<name>event</name>
<xpath-expr>if:interfaces/if:interface[if:type=if:gigabitEthernet]</xpath-expr>
</policy-variable>
</policy-variables>
<events>
<event>
<event-name>interface-self-monitoring</name>
<event-type>server-event</event-type>
<event-stream>NETCONF</event-stream>
<event-module>ietf-interfacs</event-module>
<event>if:interfaces/if:interface[if:type=if:gigabitEthernet]</event>
</event>
</events>
<conditions>
<condition>
<name>if-monitoring-condition</name>
<condition-xpath>event/statistics/in-errors > 1000 </condition-xpath>
</condition>
</conditions>
<actions>
<action>
<name>if-matched-statistics</name>
<action-element>
</action-element>
<time-schedule>
<period>5</period>
<count>12</count>
</time-schedule>
</action>
</actions>
<ecas>
<eca>
<name>interface-eca-handling</name>
<event-name>interface-self-monitoring</event-name>
<condition-action>
<name>sustained-event</name>
<condition>if-monitoring-condition</condition>
<action>if-matched-statistics</action>
</condition-action>
</eca>
</ecas>
</gnca>
<notification xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
<eventTime>2016-11-21T13:51:00Z</eventTime>
<eca-report>
<interfaces
xmlns="urn:ietf:params:xml:ns:yang:ietf-interfaces"
xmlns:ianaift="urn:ietf:params:xml:ns:yang:iana-if-type">
<interface>
<name>GE0</name>
<type>ianaift:gigabitEthernet</type>
<enabled>false</enabled>
</interface>
<interface>
<name>GE1</name>
<type>ianaift:gigabitEthernet</type>
<enabled>true</enabled>
</interface>
<interface>
<name>GE2</name>
<type>ianaift:gigabitEthernet</type>
<enabled>true</enabled>
</interface>
</eca-report>
</notification>
<notification xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
<eventTime>2016-11-21T13:53:00Z</eventTime>
<eca-execution>
<oper-status>completed</oper-status>
<event-name>interface-self-monitoring</name>
<event-type>server-event</event-type>
<event-stream>NETCONF</event-stream>
<event-module>ietf-interfacs</event-module>
<period>5</period>
<count>12</count>
</eca-execution>
</notification>
In this example, the event name is set to 'interface-self-monitoring', the event type is set to 'server-event', the name of 'condition-action' is corresponding to standard function call 'sustained-event'.
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