Internet DRAFT - draft-chisholm-netconf-event
draft-chisholm-netconf-event
Network Working Group S. Chisholm
Internet-Draft K. Curran
Expires: April 27, 2006 Nortel
H. Trevino
Cisco
October 24, 2005
Netconf Event Messages
draft-chisholm-netconf-event-01.txt
Status of this Memo
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Copyright Notice
Copyright (C) The Internet Society (2005).
Abstract
This memo defines a framework for sending asynchronous messages, or
event messages in Netconf. It defines both the operations necessary
to support this concept, and also discusses implications for the
mapping to application protocols.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1 Definition of Terms . . . . . . . . . . . . . . . . . . . 4
1.2 Event Messages in Netconf . . . . . . . . . . . . . . . . 5
2. Event-Related Operations . . . . . . . . . . . . . . . . . . . 6
2.1 Subscribing to receive Events . . . . . . . . . . . . . . 6
2.1.1 create-subscription . . . . . . . . . . . . . . . . . 6
2.2 Sending Events . . . . . . . . . . . . . . . . . . . . . . 7
2.2.1 Events . . . . . . . . . . . . . . . . . . . . . . . . 7
2.3 Changing the Subscription . . . . . . . . . . . . . . . . 8
2.3.1 modify-subscription . . . . . . . . . . . . . . . . . 8
2.4 Terminating the Subscription . . . . . . . . . . . . . . . 9
2.4.1 cancel-subscription . . . . . . . . . . . . . . . . . 10
3. Supporting Concepts . . . . . . . . . . . . . . . . . . . . . 11
3.1 Capabilities Exchange . . . . . . . . . . . . . . . . . . 11
3.2 Querying Subscription Properties . . . . . . . . . . . . . 11
3.3 RPC One-way Messages . . . . . . . . . . . . . . . . . . . 11
3.4 User-Specified Filters . . . . . . . . . . . . . . . . . . 12
3.4.1 Named Profiles . . . . . . . . . . . . . . . . . . . . 12
3.4.2 Just-in-time Filtering . . . . . . . . . . . . . . . . 12
3.5 Event Classes . . . . . . . . . . . . . . . . . . . . . . 12
3.6 Defining Event Messages . . . . . . . . . . . . . . . . . 13
3.7 Interleaving Messages . . . . . . . . . . . . . . . . . . 13
4. XML Schema for Event Messages . . . . . . . . . . . . . . . . 15
5. Mapping to Application Protocols . . . . . . . . . . . . . . . 19
5.1 SSH . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
5.2 BEEP . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
5.2.1 One-way Messages in Beep . . . . . . . . . . . . . . . 20
5.3 SOAP . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.3.1 A Netconf over Soap over HTTP Example . . . . . . . . 21
6. Security Considerations . . . . . . . . . . . . . . . . . . . 24
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 25
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 26
A. Potential Event Content . . . . . . . . . . . . . . . . . . . 27
A.1 Event Identifier . . . . . . . . . . . . . . . . . . . . . 27
A.2 Resource Instance . . . . . . . . . . . . . . . . . . . . 27
A.3 Event Time . . . . . . . . . . . . . . . . . . . . . . . . 27
A.4 Perceived Severity . . . . . . . . . . . . . . . . . . . . 27
A.5 Probable Cause . . . . . . . . . . . . . . . . . . . . . . 28
A.6 Specific Problem . . . . . . . . . . . . . . . . . . . . . 28
A.7 Trend Indication . . . . . . . . . . . . . . . . . . . . . 28
A.8 Additional Alarm Text . . . . . . . . . . . . . . . . . . 28
A.9 Threshold Identifier . . . . . . . . . . . . . . . . . . . 28
A.10 Threshold Type . . . . . . . . . . . . . . . . . . . . . . 29
A.11 Observed Value . . . . . . . . . . . . . . . . . . . . . . 29
A.12 State Change Information . . . . . . . . . . . . . . . . . 29
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B. Configuration Event Class Messages . . . . . . . . . . . . . . 30
B.1 Types of Configuration Events . . . . . . . . . . . . . . 30
B.2 Configuration Event Content . . . . . . . . . . . . . . . 31
B.2.1 Target Datastore . . . . . . . . . . . . . . . . . . . 31
B.2.2 User Info . . . . . . . . . . . . . . . . . . . . . . 31
B.2.3 Data Source . . . . . . . . . . . . . . . . . . . . . 31
B.2.4 Operation . . . . . . . . . . . . . . . . . . . . . . 31
B.2.5 Context . . . . . . . . . . . . . . . . . . . . . . . 32
B.2.6 Entered Command . . . . . . . . . . . . . . . . . . . 32
B.2.7 New Config . . . . . . . . . . . . . . . . . . . . . . 32
B.2.8 Old Config . . . . . . . . . . . . . . . . . . . . . . 32
C. Design Alternative . . . . . . . . . . . . . . . . . . . . . . 33
C.1 Server Session Initiation . . . . . . . . . . . . . . . . 33
C.2 Event Subscription Initiation . . . . . . . . . . . . . . 33
C.2.1 Establishment . . . . . . . . . . . . . . . . . . . . 33
C.2.2 Teardown . . . . . . . . . . . . . . . . . . . . . . . 34
C.2.3 Suspend And Resume . . . . . . . . . . . . . . . . . . 34
C.2.4 Lifecycle . . . . . . . . . . . . . . . . . . . . . . 34
D. Netconf Event Messages and Syslog . . . . . . . . . . . . . . 35
D.1 Leveraging Syslog Field Definitions . . . . . . . . . . . 35
D.1.1 Field Mapping . . . . . . . . . . . . . . . . . . . . 36
D.1.2 Severity Mapping . . . . . . . . . . . . . . . . . . . 37
D.2 Syslog within NETCONF Events . . . . . . . . . . . . . . . 37
D.2.1 Motivation . . . . . . . . . . . . . . . . . . . . . . 37
D.2.2 Embedding syslog messages in a NETCONF Event . . . . . 37
D.2.3 Supported Forwarding Options . . . . . . . . . . . . . 38
Intellectual Property and Copyright Statements . . . . . . . . 40
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1. Introduction
NETCONF [NETCONF-PROTO] can be conceptually partitioned into four
layers:
Layer Example
+-------------+ +-----------------------------+
| Content | | Configuration data |
+-------------+ +-----------------------------+
| |
+-------------+ +-----------------------------+
| Operations | | <get-config>, <edit-config> |
+-------------+ +-----------------------------+
| |
+-------------+ +-----------------------------+
| RPC | | <rpc>, <rpc-reply> |
+-------------+ +-----------------------------+
| |
+-------------+ +-----------------------------+
| Application | | BEEP, SSH, SSL, console |
| Protocol | | |
+-------------+ +-----------------------------+
This document defines a framework for sending asynchronous messages,
or event messages in Netconf. It defines both the operations
necessary to support this concept, and also discusses implications
for the mapping to application protocols.
Figure 1
1.1 Definition of Terms
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 RFC 2119 [3].
Element: An XML Element[XML].
Managed Entity: A node, which supports Netconf[NETCONF] and has
access to management instrumentation. This is also known as the
Netconf server.
Managed Object: A collection of one of more Elements that define an
abstract thing of interest.
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1.2 Event Messages in Netconf
An event is something that happens which may be of interest - a
configuration change, a fault, a change in status, crossing a
threshold, or an external input to the system, for example. Often
this results in an asynchronous message, sometimes referred to as a
notification or event message, being sent out to interested parties
to notify them that this event has occurred.
This memo defines a mechanism whereby the Netconf client indicates
interest in receiving event messages from a Netconf server by
creating a subscription to receive events. The Netconf server
replies to indicate whether the subscription request was successful
and, if it was successful, begins sending the event messages to the
Netconf client as the events occur within the system. These event
messages will continue to be sent until either the Netconf session is
terminated or an explicit command to cancel the subscription is sent.
The event subscription allows a number of options to enable the
Netconf client to specify which events are of interest. These are
specified when the subscription is created, but can be modified later
using a modify subscription command.
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2. Event-Related Operations
2.1 Subscribing to receive Events
The event subscription is initiated by the Netconf client and
responded to by the Netconf server. When the event subscription is
created, the events of interest are specified.
It is possible to create more than one event subscription on a single
underlying connection. Each event subscription therefore has its own
unique identifier.
Content for an event subscription can be selected by specifying which
event classes are of interest and /or by applying user-specified
filters.
2.1.1 create-subscription
<create-subscription>
Description:
This command initiates an event subscription which will send
asynchronous event messages to the initiator of the command until
the <cancel-subscription > command is sent.
Parameters:
Event Classes:
An optional parameter that indicates which event classes are of
interest. If not present, events of all classes will be sent.
Filter:
An optional parameter that indicates which subset of all
possible events are of interest. The format is the same filter
used for other Netconf commands. If not present, all events
not precluded by other parameters will be sent. These filter
parameters can only be modified using the modify-subscription
command.
Named Profile
An optional parameter that points to separately defined filter
profile. If not present, no additional filtering will be
applied. If the separate definition of these filters is
updated, then these changes will be reflected in the filtered
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events on this subscription.
Positive Response:
If the Netconf server can satisfy the request, the server sends an
<rpc-reply> element containing a <data> element containing the
subscription ID.
Negative Response:
An <rpc-error> element is included within the <rpc-reply> if the
request cannot be completed for any reason.
2.2 Sending Events
Once the subscription has been set up, the Netconf server sends the
events asynchronously along the connection. Messages are tagged with
an event class, subscription ID, sequence number, and date and time.
2.2.1 Events
Events
<event>
Description:
An event message is sent to the initiator of an <create-
subscription> command asynchronously when an event of interest to
them has occurred. An event is a complete XML document.
Parameters:
Event Classes:
The event class or classes associated with this event
Subscription Id:
A unique identifier for this event subscription
Sequence Number:
A sequentially increasing number to uniquely identify event
messages for this subscription.
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Data and Time:
The date and time that the event was sent by the Netconf
server.
Positive Response:
No response.
Negative Response:
No response.
2.2.1.1 Event Message
The NETCONF Event message structure is shown in the following figure.
_____________
|RPC-Header||
|__________||
|message-id||
|__________||
____________________________________________________________________
|| Event Header || Data |
||__________________________________________________________||______|
|| subscriptionId| eventClasses| sequenceNumber| dataAndTime|| |
||_______________|_____________|_______________|____________||______|
2.3 Changing the Subscription
After an event subscription has been established, the Netconf client
can initiate a request to change properties of the event
subscription. This prevents loss of events that might otherwise
occur during a tear down and recreation of the event subscription.
This command is responded to by the Netconf server
2.3.1 modify-subscription
<modify-subscription>
Description:
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Change properties of the event subscription.
Parameters:
Subscription Id:
A unique identifier for this event subscription.
Event Classes:
An optional parameter that indicates which Event Classes are of
interest. If not present, events of all classes will be sent.
Filter:
An optional parameter that indicates which subset of all
possible events that are of interest. The format is the same
filter used for other Netconf commands. If not present, all
events not precluded by other parameters will be sent. These
filter parameters can only be modified using the modify-
subscription command.
Named Profile:
An optional parameter that points to separately defined filter
profile. If not present, no additional filtering will be
applied. If the separate definition of these filters is
updated, then these changes will be reflected in the events
seen on this subscription.
Positive Response:
If the Netconf server was able to satisfy the request, an <rpc-
reply> is sent that includes an <ok> element.
Negative Response:
An <rpc-error> element is included within the <rpc-reply> if the
request cannot be completed for any reason.
2.4 Terminating the Subscription
Closing of the event subscription is initiated by the Netconf client.
The specific subscription to be closed is specified using a
subscription ID. The Netconf server responds. Note that the Netconf
session may also be torn down for other reasons and this will also
result in the subscription being cancelled, but is not subjected to
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the behaviour of this command.
2.4.1 cancel-subscription
<cancel-subscription>
Description:
Tear down the event subscription.
Parameters:
Subscription Id:
A unique identifier for this event subscription.
Positive Response:
If the Netconf server was able to satisfy the request, an <rpc-
reply> is sent that includes an <ok> element.
Negative Response:
An <rpc-error> element is included within the <rpc-reply> if the
request cannot be completed for any reason.
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3. Supporting Concepts
3.1 Capabilities Exchange
The ability to process and send event messages is advertised during
the capability exchange between the Netconf client and server.
"urn:ietf:params:xml:ns:netconf:event:1.0"
For Example
<hello xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<capabilities>
<capability>
urn:ietf:params:xml:ns:netconf:base:1.0
</capability>
<capability>
urn:ietf:params:xml:ns:netconf:capability:startup:1.0
</capability>
<capability>
urn:ietf:params:xml:ns:netconf:event:1.0
</capability>
</capabilities>
<session-id>4</session-id>
</hello>
3.2 Querying Subscription Properties
This area is for further study. [Editor's Note: A read-only schema
might get added, to enable the get operation to retrieve this
information. Making it writable would add to the complexity of the
implementation and also lead to the temptation to keep adding options
and features which could lead us down a slippery slope to end up with
a similar solution to what we had in SNMP, which no one could ever
figure out how to use.]
3.3 RPC One-way Messages
In order to support the concept that each individual event message is
a well-defined XML-document that can be processed without waiting for
all events to come in, it makes sense to define events, not as an
endless reply to a subscription command, but as independent messages
that originate from the Netconf server. In order to support this
model, this memo introduces the concept of a one-way RPC message.
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The one-way RPC message is similar to the two-way RPC message, except
that no response is expected to the command. In the case of events,
this RPC will originate from the Netconf server, and not the Netconf
client.
3.4 User-Specified Filters
3.4.1 Named Profiles
A named profile is a filter that is created ahead of time and applied
at the time an event subscription is created or modified. Note that
changes to the profile after the subscription has been created alter
the event messages received.
3.4.2 Just-in-time Filtering
Just-in-time filtering is explicitly stated when the event
subscription is created. It can only be changed using the modify
subscription command. This is specified via the Filter parameter.
3.5 Event Classes
Events can be broadly classified into one more event classes.
The initial set of event classes is fault, information, state, audit,
configuration, data, maintenance, metrics, security and heartbeat.
A fault event message is generated when a fault condition (error or
warning) occurs. Examples of fault events could be a communications
alarm, environmental alarm, equipment alarm, processing error alarm,
quality of service alarm, or a threshold crossing event. See RFC3877
and RFC2819 for more information.
A configuration event, alternatively known as an inventory event, is
used to notify that hardware, software, or a service has been added/
changed/removed. In keeping aligned with NETCONF protocol
operations, configuration events may included copy configuration
event, delete configuration event, or the edit configuration event
(create, delete, merge, replace).
A state event indicates a change from one state to another, where a
state is a condition or stage in the existence of a managed entity.
State change events are seen in many specifications. For Entity
state changes, see [Entity-State-MIB] for more information.
Audit events provide event of very specific actions within a managed
device. In isolation an audit events provides very limited data. A
collection of audit information forms an audit trail.
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A data dump event is an asynchronous event containing information
about a system, its configuration, state, etc.
A maintenance event signals the beginning, process or end of an
action either generated by a manual or automated maintenance action.
A metrics event contains a metric or a collection of metrics. This
includes performance metrics.
A heart beat event is sent periodically to enable testing that the
communications channel is still functional. Although widely used
throughout the industry, no current corresponding work within the
IETF. However, other standards bodies such as the TeleManagement
Forum have similar definitions.
An Information event is something that happens of interest which is
within the expected operational behaviour and not otherwise covered
by another class.
3.6 Defining Event Messages
Event Messages are defined ahead of time by defining an XML element
and assigning it to particular event classes. This will be done
using an "eventClasses" attribute. See 'Framework for Netconf Data
Models' [Netconf-Datamodels] for more information.
3.7 Interleaving Messages
While each Netconf message must be a complete XML document, the
design of the event system allows for the interleaving of complete
asynchronous event messages with complete synchronous messages. It
is possible to still send command-response type messages such as
<modify-subscription> while events are being generated. The only
restriction is that each message must be complete
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The following sequence diagram demonstrates an example Netconf
session where after basic session establishment and capability
exchange, Netconf client (C), subscribes to receive events. The
Netconf server (S), starts sending event messages as events of
interest happen within the system. The Netconf client decides to
change the characteristics of their event subscription so sends a
<modify-subscription> command. Before the Netconf server, receives
this command, another event is generated and the Netconf server
starts to send the event message. The Netconf server finishes
sending this event message before processing the <modify-
subscription> command and sending the reply.
C S
| |
| capability exchange |
--------------------------->|
<-------------------------->|
| |
| <create-subscription> |
|-------------------------->|
|<--------------------------|
| |
| <event> |
|<--------------------------|
| |
| <event> |
|<--------------------------|
| |
| <modify-subscription> |
|-------------------------->| (buffered)
| <event> |
|<--------------------------|
| <rpc-reply> |
|<--------------------------|
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4. XML Schema for Event Messages
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns="urn:ietf:params:xml:ns:netconf:event:1.0"
xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0"
targetNamespace="urn:ietf:params:xml:ns:netconf:event:1.0"
elementFormDefault="qualified"
attributeFormDefault="unqualified"
xml:lang="en">
<!--
import standard XML definitions
-->
<xs:import namespace="http://www.w3.org/XML/1998/namespace"
schemaLocation="http://www.w3.org/2001/xml.xsd">
<xs:annotation>
<xs:documentation>
This import accesses the xml: attribute groups for the
xml:lang as declared on the error-message element.
</xs:documentation>
</xs:annotation>
</xs:import>
<!-- import base netconf definitions -->
<xs:import namespace="urn:ietf:params:xml:ns:netconf:base:1.0"
schemaLocation="urn:ietf:params:xml:ns:netconf:base:1.0" />
<!-- ************** Type definitions ***********************-->
<xs:simpleType name="SubscriptionID">
<xs:annotation>
<xs:documentation>
The unique identifier for this particular subscription
within the session.
</xs:documentation>
</xs:annotation>
<xs:restriction base="xs:string"/>
</xs:simpleType>
<xs:simpleType name="SequenceNumber">
<xs:annotation>
<xs:documentation>
A monotonically increasing integer. Starts at 0.
Always increases by just one. Roll back to 0 after maximum
value
is reached.
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</xs:documentation>
</xs:annotation>
<xs:restriction base="xs:integer"/>
</xs:simpleType>
<xs:complexType name="EventClassType"/>
<xs:element name="EventClass"
type="EventClassType" abstract="true"/>
<xs:element name="fault" type="EventClassType"
substitutionGroup="EventClass"/>
<xs:element name="information" type="EventClassType"
substitutionGroup="EventClass"/>
<xs:element name="state" type="EventClassType"
substitutionGroup="EventClass"/>
<xs:element name="configuration" type="EventClassType"
substitutionGroup="EventClass"/>
<xs:element name="data" type="EventClassType"
substitutionGroup="EventClass"/>
<xs:element name="maintenance" type="EventClassType"
substitutionGroup="EventClass"/>
<xs:element name="metrics" type="EventClassType"
substitutionGroup="EventClass"/>
<xs:element name="security" type="EventClassType"
substitutionGroup="EventClass"/>
<xs:element name="heartbeat" type="EventClassType"
substitutionGroup="EventClass"/>
<xs:complexType name="EventClasses">
<xs:sequence>
<xs:element name="class" type="EventClassType"
maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
<!-- ************** Symmetrical Operations ********************-->
<!--
<create-subscription> operation
-->
<xs:complexType name="createSubscriptionType">
<xs:complexContent>
<xs:extension base="netconf:rpcOperationType">
<xs:sequence>
<xs:element name="eventClasses"
type="EventClasses" minOccurs="0"/>
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<xs:element name="filter"
type="netconf:filterInlineType"
minOccurs="0"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="create-subscription"
type="createSubscriptionType"
substitutionGroup="netconf:rpcOperation"/>
<!--
<modify-subscription> operation
-->
<xs:complexType name="modifySubscriptionType">
<xs:complexContent>
<xs:extension base="netconf:rpcOperationType">
<xs:sequence>
<xs:element name="subscriptionId"
type="SubscriptionID" />
<xs:element name="eventClasses"
type="EventClasses" minOccurs="0"/>
<xs:element name="filter"
type="netconf:filterInlineType"
minOccurs="0"/>
<xs:element name="namedProfile
type="xs:string" minOccurs="0"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="modify-subscription"
type="modifySubscriptionType"
substitutionGroup="netconf:rpcOperation"/>
<!--
<cancel-subscription> operation
-->
<xs:complexType name="cancelSubscriptionType">
<xs:complexContent>
<xs:extension base="netconf:rpcOperationType">
<xs:sequence>
<xs:element name="subscriptionId"
type="SubscriptionID" />
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
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<xs:element name="cancel-subscription"
type="cancelSubscriptionType"
substitutionGroup="netconf:rpcOperation"/>
<!-- ************** One-way Operations ******************-->
<xs:complexType name="rpcOneWayType">
<xs:group ref="rpc-one-way"/>
<xs:attribute name="message-id" type="xs:string"
use="optional"/>
</xs:complexType>
<xs:group name="rpc-one-way">
<xs:sequence>
<xs:element name="data" type="netconf:dataInlineType"
minOccurs="0"/>
</xs:sequence>
</xs:group>
<!--
<Event> operation
-->
<xs:complexType name="EventType">
<xs:complexContent>
<xs:extension base="rpcOneWayType">
<xs:sequence>
<xs:element name="subscriptionId"
type="SubscriptionID" />
<xs:element name="eventClasses"
type="EventClasses" />
<xs:element name="sequenceNumber"
type="SequenceNumber" />
<xs:element name="dateAndTime"
type="xs:dateTime" >
<xs:annotation>
<xs:documentation>
The date and time that the event was sent by the
netconf server.
<xs:docuemntation>
</xs:annotation>
</xs:element>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="event" type="EventType"/>
</xs:schema>
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5. Mapping to Application Protocols
Currently, the Netconf family of specification allows for running
Netconf over a number of application protocols, some of which support
multiple configurations. Some of these options will be better suited
for supporting events then others.
5.1 SSH
Session establishment and two-way messages are based on the Netconf
over SSH transport mapping [NETCONF-SSH]
One-way messages are supported as follows: Once the session has been
established and capabilities have been exchanged, the server may send
complete XML documents to the Netconf client containing rpc-one-way
elements. No response is expected from the Netconf client.
As the other examples in [NETCONF-SSH] illustrate, a special
character sequence, MUST be sent by both the client and the server
after each XML document in the NETCONF exchange. This character
sequence cannot legally appear in an XML document, so it can be
unambiguously used to identify the end of the current document in the
event of an XML syntax or parsing error, allowing resynchronization
of the NETCONF exchange.
The NETCONF over SSH session to receive an event might look like
this:
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<?xml version="1.0" encoding="UTF-8"?>
<rpc-one-way message-id="105"
xmlns="urn:ietf:params:xml:ns:netconf:event:1.0">
<event>
<subscriptionID>123456</subscriptionID>
<eventClass><configuration/><audit/></eventClass>
<sequenceNumber>2</sequenceNumber>
<dateAndTime>2000-01-12T12:13:14Z</dateAndTime>
<data>
<user>Fred Flinstone</user>
<operation>
<edit-config>
<target>
<running/>
</target>
<config>
<top xmlns="http://example.com/schema/1.2/config">
<interface>
<name>Ethernet0/0</name>
<mtu>1500</mtu>
</interface>
</top>
</config>
</edit-config>
</operation>
</data>
</event>
</rpc-one-way>
]]>
]]>
5.2 BEEP
Session establishment and two-way messages are based on the Netconf
over BEEP transport mapping NETCONF-BEEP
5.2.1 One-way Messages in Beep
One-way messages can be supported either by mapping to the existing
one-to-many BEEP construct or by creating a new one-to-none
construct.
This area is for future study.
5.2.1.1 One-way messages via the One-to-many Construct
Messages in one-to-many exchanges: "rcp", "rpc-one-way", "rpc-reply"
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Messages in positive replies: "rpc-reply", "rpc-one-way"
5.2.1.2 One-way messages via the One-to-none Construct
Note that this construct would need to be added to an extension or
update to 'The Blocks Extensible Exchange Protocol Core' RFC 3080.
MSG/NoANS: the client sends a "MSG" message, the server, sends no
reply.
In one-to-none exchanges, no reply to the "MSG" message is expected.
5.3 SOAP
Session management and message exchange are based on the Netconf over
SOAP transport mapping NETCONF-SOAP
Note that the use of "persistent connections" "chunked transfer-
coding" when using HTTP becomes even more important in the supporting
of events
5.3.1 A Netconf over Soap over HTTP Example
C: POST /netconf HTTP/1.1
C: Host: netconfdevice
C: Content-Type: text/xml; charset=utf-8
C: Accept: application/soap+xml, text/*
C: Cache-Control: no-cache
C: Pragma: no-cache
C: Content-Length: 465
C:
C: <?xml version="1.0" encoding="UTF-8"?>
C: <soapenv:Envelope
C: xmlns:soapenv="http://www.w3.org/2003/05/soap-envelope">
C: <soapenv:Body>
C: <rpc message-id="101"
C: xmlns="xmlns="urn:ietf:params:xml:ns:netconf:event:1.0">
C: <create-subscription>
C: </create-subscription>
C: </rpc>
C: </soapenv:Body>
C: </soapenv:Envelope>
The response:
S: HTTP/1.1 200 OK
S: Content-Type: application/soap+xml; charset=utf-8
S: Content-Length: 917
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S:
S: <?xml version="1.0" encoding="UTF-8"?>
S: <soapenv:Envelope
S: xmlns:soapenv="http://www.w3.org/2003/05/soap-envelope">
S: <soapenv:Body>
S: <rpc-reply message-id="101"
S: xmlns="urn:ietf:params:xml:ns:netconf:event:1.0">
S: <data>
S: <top xmlns="http://example.com/schema/1.2/event">
S: <subscriptionId>123456</subscriptionId
S: </top>
S: </data>
S: </rpc-reply>
S: </soapenv:Body>
S: </soapenv:Envelope>
And then some time later
S: HTTP/1.1 200 OK
S: Content-Type: application/soap+xml; charset=utf-8
S: Content-Length: 917
S:
S: <?xml version="1.0" encoding="UTF-8"?>
S: <soapenv:Envelope
S: xmlns:soapenv="http://www.w3.org/2003/05/soap-envelope">
S: <soapenv:Body>
S: <rpc-one-way message-id="101"
S: xmlns="urn:ietf:params:xml:ns:netconf:event:1.0">
S: <data>
S: <event>
S: <subscriptionID>123456</subscriptionID>
S: <eventClass><configuration/><audit/></eventClass>
S: <sequenceNumber>2</sequenceNumber>
S: <dateAndTime>2000-01-12T12:13:14Z</dateAndTime>
S: <data>
S: <user>Fred Flinstone</user>
S: <operation>
S: <edit-config>
S: <target>
S: <running/>
S: </target>
S: <config>
S: <top xmlns="http://example.com/schema/1.2/config">
S: <interface>
S: <name>Ethernet0/0</name>
S: <mtu>1500</mtu>
S: </interface>
S: </top>
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S: </config>
S: </edit-config>
S: </operation>
S: </data>
S: </event>
S: </data>
S: </rpc-one-way>
S: </soapenv:Body>
S: </soapenv:Envelope>
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6. Security Considerations
To be determined once specific aspects of this solution are better
understood. In particular, the access control framework and the
choice of transport will have a major impact on the security of the
solution
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7. Acknowledgements
Thanks to Gilbert Gagnon and Greg Wilbur for providing their input
into this document
8. References
[NETCONF] Enns, R., "NETCONF Configuration Protocol",
ID draft-ietf-netconf-prot-06, April 2005.
[NETCONF BEEP]
Lear, E. and K. Crozier, "Using the NETCONF Protocol over
Blocks Extensible Exchange Protocol (BEEP)",
ID draft-ietf-netconf-beep-05, March 2005.
[NETCONF Datamodel]
Chisholm, S. and S. Adwankar, "Framework for Netconf
Content", ID draft-chisholm-netconf-model-04.txt,
October 2005.
[NETCONF SOAP]
Goddard, T., "Using the Network Configuration Protocol
(NETCONF) Over the Simple Object Access Protocol (SOAP)",
ID draft-ietf-netconf-soap-05, April 2005.
[NETCONF SSH]
Wasserman, M. and T. Goddard, "Using the NETCONF
Configuration Protocol over Secure Shell (SSH)",
ID draft-ietf-netconf-ssh-04.txt, April 2005.
[URI] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifiers (URI): Generic Syntax", RFC 2396,
August 1998.
[XML] World Wide Web Consortium, "Extensible Markup Language
(XML) 1.0", W3C XML, February 1998,
<http://www.w3.org/TR/1998/REC-xml-19980210>.
[refs.RFC2026]
Bradner, S., "The Internet Standards Process -- Revision
3", RFC 2026, BCP 9, October 1996.
[refs.RFC2119]
Bradner, s., "Key words for RFCs to Indicate Requirements
Levels", RFC 2119, March 1997.
[refs.RFC2223]
Postel, J. and J. Reynolds, "Instructions to RFC Authors",
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RFC 2223, October 1997.
[refs.RFC3080]
Rose, M., "The Blocks Extensible Exchange Protocol Core",
RFC 3080, March 2001.
Authors' Addresses
Sharon Chisholm
Nortel
3500 Carling Ave
Nepean, Ontario K2H 8E9
Canada
Email: schishol@nortel.com
Kim Curran
Nortel
3500 Carling Ave
Nepean, Ontario K2H 8E9
Canada
Email: kicurran@nortel.com
Hector Trevino
Cisco
Suite 400
S9155 E. Nichols Ave
Englewood, CO 80112
USA
Email: htrevino@cisco.com
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Appendix A. Potential Event Content
This non-normative appendix explores possible content of event
messages. It provides field descriptions and indicates their
applicability for the various event classes. Fields specific to
configuration events (configuration event class) are provided in
Appendix B.
A.1 Event Identifier
A unique event identifier provided for event correlation purposes.
This field is used by management applications to identify events
which are generated for a single event via different mechanisms (e.g.
syslog, NETCONF). Event Id values may be re-used across re-boots.
Applicable event classes: All
A.2 Resource Instance
This field identifies the element/entity/object for which the event
is applicable.
Applicable event classes: All
A.3 Event Time
This field represents the time at which the action causing the
generation of the event has taken place. Event time field is
composed of two parts: event generation time and event sysUpTime.
Where, event generation time is a timestamp and event sysUpTime is
the SNMP sysUpTime.
Event generation time follows the syslog TIMESTAMP format defined in
draft-ietf-syslog-protocol-14.txt (derived from RFC3339 but with
additional restrictions). Event sysUpTime is of XML type integer
(0..4294967295) and it follows the same definition as sysUpTime
(TimeTicks) defined in RFC1907/RFC2578 - "The time (in hundredths of
a second) since the network management portion of the system was last
re-initialized).
Applicable event classes: All
A.4 Perceived Severity
The severity of the alarm as determined by the alarm detection point
using the information it has available [RFC3877]. The values are
cleared, indeterminate, critical, major, minor and warning.
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Applicable event classes: fault
A.5 Probable Cause
This field provides further information describing the cause of the
alarm . Allowed values for this field are the same as those listed
in RFC3877 and are derived from ITU X.733 and ITU M.3100.
Note that this concept is being evolved to be less linear, within the
ITU-T, in X.733.1, a protocol-neutral version of X.733. It may make
sense to consider alignment with this update on the concept of
probable cause, instead of the one in RFC3877 and X.733.
Applicable event classes: fault
A.6 Specific Problem
This parameter is optional. When present, it identifies further
refinements to the Probable cause of the alarm. This definition
follows ITU X.733
Applicable event classes: fault
A.7 Trend Indication
This parameter indicates the trend of the alarm against the managed
resource Allowed values for this field are as specified in RFC3877
and follow the ITU X.733 value definitions
Applicable event classes: fault
A.8 Additional Alarm Text
This parameter is provided to allow implementation to include a
textual description of the alarm
Applicable event classes: fault
A.9 Threshold Identifier
This field holds the identifier of the monitored variable for which
the threshold has set. This is analogous to the alarmVariable
OBJECT-TYPE in RFC2819.
Applicable event classes: fault (optional - useful for threshold
crossing alarms)
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A.10 Threshold Type
This parameter is used to indicate the direction of the threshold
crossing: rising, falling, or clear.
Note that while compatible with RMON, this method of reporting
thresholds is overloaded. Consideration should be given to be able
to properly distinguish between crossing a lower threshold (falling)
to be out of range and crossing an upper threshold to be back within
an acceptable range (falling). Similarly, the 2 types of rising
should be distinguishable.
Applicable event classes: fault (optional - useful in the case
threshold crossing alarms)
A.11 Observed Value
The value of the monitored parameter (Threshold Identifier) for the
last sampling period. This parameter follows the alarmValue
definition in RFC2819. This field is in two parts - the value and
the units of measure.
Applicable event classes: fault (optional - useful in the case
threshold crossing alarms)
A.12 State Change Information
This parameter holds the name and values of the state attributes
whose values have changed and are being reported.
This is a parameter composed of three fields: Attribute Name, Old
Value, and New Value. The definitions given in
draft-ietf-entmib-state-07.txt for state attributes and values are
being followed.
Applicable event classes: state
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Appendix B. Configuration Event Class Messages
This non-normative appendix provides a detailed description of a
configuration change event definition in support of the configuration
operations, particularly those defined by the NETCONF protocol.
B.1 Types of Configuration Events
Configuration event messages include:
o Resource Related Events
o Netconf Related Events
Resource Related Events are those indicate that a change has occurred
around hardware, software, services or other managed resources within
a system. Specific events includes
o Resource Added
o Resource Removed
o Resource Modified
Netconf related events are those which correspond to the execution of
explicit Netconf operations. These include:
o copy-config event
* This is a data store level event generated following the
successful completion of a copy-config operation. This
represents the creation of a new configuration file or
replacement of an existing one.
o delete-config event
* This is a data store level event generated following the
successful completion of a delete-config operation. This
represents the deletion of a configuration file.
o edit-config event
* This is an event generated following a change in configuration
due to an edit-config operation, e.g., due to the completion of
an edit-config operation which successfully changed some part
of the configuration. See edit-config error-options (stop-on-
error, ignore-error, rollback-on-error) The contents of this
event are dependent on the type of operation performed: edit-
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config (merge, replace, delete, create). This event is not
intended to report completely unsuccessful configuration
operations.
o lock-config event
o unlock-config event
B.2 Configuration Event Content
The applicability of these fields to other event classes is for
further study.
B.2.1 Target Datastore
Target datastore refers to the data store (startup, candidate,
running) which was modified by the management operation.
B.2.2 User Info
This is used to convey information describing who originated the
configuration event and the means for submitting the request. The
user info field contains the following information:
user Name: User id which was authorized to execute the associated
management operation causing the generation of this event.
source Indicator: Indicates the method employed to initiate the
management operation telnet, Netconf, console, etc.
transaction Id: If available, this field contains a unique
identifier for the associated management operation. This is
implementation dependent and may require additional information to
be communicated between server and client. A possible option is
to make use of the message-id in the NETCONF rpc header
B.2.3 Data Source
The data source is used, for example, in the copy configuration
command to indicated the source of information used in the copy
operation
B.2.4 Operation
Operation is used, for example, in the edit configuration command to
indicated the specific operation that has taken place - create,
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delete, merge, replace.
B.2.5 Context
The configuration sub-mode under which the command was executed.
This field may be either CLI (text) or a Netconf command. [Editor's
Note: how do we tell the difference?]
B.2.6 Entered Command
The command entered and executed on the device. This can either be
CLI (text) or a Netconf command.[Editor's Note: how do we tell the
difference?]
B.2.7 New Config
The device's configuration following the successful execution of the
entered command. This can either be CLI (text) or a Netconf
command.[Editor's Note: how do we tell the difference?]
B.2.8 Old Config
The configuration prior to the execution of the entered command.
This can either be CLI (text) or a Netconf command.[Editor's Note:
how do we tell the difference?]
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Appendix C. Design Alternative
C.1 Server Session Initiation
Currently the NETCONF protocol requires session establishment to be
initiated by the NETCONF client. With the introduction of event
messages in NETCONF as well deployments which might require the
"call-home" feature to get around firewall and/or NAT issues, the
ability for a NETCONF server to initiate sessions becomes important.
Other potential uses of this feature includes the following
deployment scenario: NE registration/auto-configuration where the
device is pre-configured with the target destination for the
management station where it needs to register and download its
configuration. When managing large numbers of devices (e.g. CPEs)
this also allows for increased scalability since the management
station does not need to maintain established sessions to all managed
devices.
This appendix proposes extensions to the event subscription session
establishment procedures and related operations to allow for server
session initiation.
Note that the security implications of this approach, compared with
more traditional, well understood models, is for further study.
C.2 Event Subscription Initiation
The subscription information as described in the body of this
document indicates that it is transient in nature (i.e. it is not
persisted and it is only applicable through the life of the session).
This section describes additional functionality for persisting event
subscription information and allowing the NETCONF server (e.g.
network element) to initiate the event subscription session.
QUICK SUMMARY: <create-subscription>, <cancel-subscription>,
<modify-subscription> used in same manner as described in doc. It
may use useful to allow a client and server to re-establish a events
subscription. This would be yet another capability to allow session
initiation by the server.
C.2.1 Establishment
In order to establish an event subscription, a client must issue a
<create-subscription> message request. Upon a successful response
from the server (e.g. network element) the event subscription is
established. With this modified persistent version of the
subscription, the Netconf server would maintain the subscription
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information as part of its configuration.
C.2.2 Teardown
A event subscription is torn down when a) the client issues a
<cancel-subscription> message and it is successfully processed by
the server (i.e. the server issues a positive response) or b) the
Netconf session carrying the event subscription goes down for any
reason.
If the subscription is not persistent, the user must create a new
subscription with the exact same parameters as the original session.
If instead, subscriptions were persistent, as part of the network
element's configuration, the client simply needs to re-establish the
session by specifying the subscription Id.
C.2.3 Suspend And Resume
Since the purpose of the <cancel-subscription> operation is to stop
event message forwarding and due to its transient nature removes all
subscription configuration; a different mechanism might be needed for
shutting down the session but preserving the subscription information
thus allowing the NETCONF server to re-establish the parameters and
reproduce the subscription.
The suspend and resume commands would allows a NETCONF client to
suspend event message forwarding without removing the existing
subscription information. Operations <suspend-subscription> and
><resume-subscription> are proposed for this purpose.
[Editor's Note: how would this work in the case of accidental session
termination?]
C.2.4 Lifecycle
Configuration information associated with the event subscription
(event classes and filters) could persist beyond the life of the
event subscription session. (i.e. it is maintained by the network
element as part of its configuration). This configuration
information is subject to the behaviour of the datastore it resides
in and may or may not persist across re-boots (e.g. it could be part
of the running configuration but not the startup configuration).
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Appendix D. Netconf Event Messages and Syslog
This appendix describes the mapping between syslog message fields and
NETCONF event message fields. The purpose of this mapping is to
provide an unambiguous mapping to enable consistent multi-protocol
implementations as well as to enable future migration.
The second part of the appendix describes an optional capability to
embed an entire syslog message (hereafter referred to as syslog
message(s) to avoid confusion with the message field in syslog)
within a NETCONF event message.
D.1 Leveraging Syslog Field Definitions
This section provides a semantic mapping between NETCONF event fields
and syslog message fields.
-------------------------------------------------------------------
| PRI | HEADER | MESSAGE |
-------------------------------------------------------------------
| FACILITY | SEVERITY | TIMESTAMP | HOSTNAME | TAG CONTENT |
-------------------------------------------------------------------
Figure 2 - syslog message (RFC3164)
-------------------------------------------------------------------
| HEADER | STRUCTURED DATA | MESSAGE |
-------------------------------------------------------------------
Figure 3 - syslog message (draft-ietf-syslog-protocol-14.txt)
HEADER (Version, Facility, Severity, Truncate, Flag, TimeStamp,
HostName, AppName, ProcId, MsgId)
STRUCTURED DATA (Zero or more Structured Data Elements - SDEs)
MESSAGE ( Text message )
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D.1.1 Field Mapping
------------------------------------------------------
RFC3164 Syslog ID NETCONF Event
------------------------------------------------------
VERSION
------------------------------------------------------
FACILITY FACILITY
------------------------------------------------------
SEVERITY SEVERITY PerceivedSeverity
------------------------------------------------------
TRUNCATE FLAG
------------------------------------------------------
TIMESTAMP TIMESTAMP EventTime
------------------------------------------------------
HOSTNAME HOSTNAME EventOrigin
------------------------------------------------------
TAG APP-NAME EventOrigin
------------------------------------------------------
PROC-ID
------------------------------------------------------
MSG-ID
------------------------------------------------------
CONTENT CONTENT AdditionalText
------------------------------------------------------
Figure 4 - syslog to NETCONF Event field mapping
Notes:
VERSION: Schema version is found in XML Schema namespace. However,
no correspondence to syslog.
FACILITY: No well defined semantics for this field. Therefore not
used at this time.
TRUNCATE: Not applicable. NETCONF events must be complete XML
documents therefore cannot be truncated.
TIME: TIMESTAMP in syslog ID is derived from RFC3339 but with
additional restrictions
PROC-ID: No equivalent field
CONTENT: This is a free form text field with not defined semantics.
The contents of this field may be included in the AdditionalText
field.
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D.1.2 Severity Mapping
The severity value mappings stated in (draft-ietf-syslog-protocol-14)
are used:
ITU Perceived Severity syslog SEVERITY
Critical Alert
Major Critical
Minor Error
Warning Warning
Indeterminate Notice
Cleared Notice
Figure 5. ITU PerceivedSeverity to syslog SEVERITY mapping.
D.2 Syslog within NETCONF Events
D.2.1 Motivation
The syslog protocol (RFC3164) is widely used by equipment vendors as
a means to deliver event messages. Due to the widespread use of
syslog as well as a potential phased availability and coverage of
NETCONF events by equipment vendors, it is envisioned that users will
also follow a phased migration. As a way to facilitate migration and
at the same time allow equipment vendors to provide comprehensive
event coverage over a NETCONF event subscription session, syslog
messages could be embedded in their entirety within the body of a
NETCONF event message.
The information provided in this appendix describes a mechanism to
leverage syslog messages for the purpose of complementing the
available Netconf event message set. The intent is to promote the
use of the Netconf interface and not to simply provide a wrapper and
additional delivery mechanism for syslog messages. Netconf events
are intended to be well defined and structured, therefore providing
an advantage over the unstructured and often times arbitrarily
defined syslog messages (i.e. the message field).
Covered herein is the syslog protocol as defined in RFC3164 and
draft-ietf-syslog-protocol-14.txt.
D.2.2 Embedding syslog messages in a NETCONF Event
When event messages are supported, the default behaviour for a
NETCONF server is to send Netconf event messages over an established
event subscription. As an option, the NETCONF server may embed a
syslog message in its entirety (e.g. RFC3164 - PRI, Header, and
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Message fields), placing it within the Event Info field (SyslogInfo
sub-field) - see Figure 1.
_____________________________________________________
| NETCONF Event Header | Data |
|________________________|___________________________|
| | Event Info |
|________________________|___________________________|
| |
v v
____________________________
| Event Fields | SyslogInfo |
|___________________________|
Figure 1 - Embedding syslog in a NETCONF Event Messages
D.2.3 Supported Forwarding Options
Three event forwarding options may be supported by the NETCONF
server: a) XML only (mandatory if NETCONF events capability is
supported) b) XML and syslog (Optional) c) syslog only (optional)
D.2.3.1 XML and Syslog option - Forwarding Behaviour
It is possible, due to coverage, for a given NETCONF implementation
to not support a comprehensive set of Netconf event messages.
Therefore, it is possible for a given event to trigger the generation
of a syslog message without a Netconf-aware counterpart. In such
situations, the NETCONF server could form a NETCONF event message,
embed the syslog message in the SyslogInfo field and forward the
NETCONF event messages to all subscribed destinations. Otherwise,
both Netconf event and syslog messages must be included in the Event
Info field.
D.2.3.2 Event Class Identification
The event class field is found in the NETCONF event header
information as described in the main body of this document. It
conveys information describing that type of event for which the event
message is generated and lets the consumer of the message know what
to expect. NETCONF event messages which only contain a syslog
message (Options b or c) must have the EventClass field set to
"information". [Editor's Note: This needs to be thought through. It
may not be the best option.] The NETCONF client parses the message
in the same manner as any other message, finds the normal fields
empty [Editor's Note: or not present?] and either proceeds to parse
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the SyslogInfo field or hands the syslog message to the entity
responsible for processing syslog messages.
D.2.3.3 Event Subscription Options
A NETCONF client may request subscription to options b) XML and
syslog or c) syslog only listed in "Supported Forwarding Options" at
subscription time via the user-specified filter. The FILTER or NAMED
FILTER parameter in <create-subscription>. As previously indicated,
the default behaviour is to forward Netconf XML only event messages.
D.2.3.4 Supported Forwarding Option Discovery
A potential means for a NETCONF server to convey its feature set
support is via capabilities. However, in this particular case, the
event content is not a protocol feature therefore other means are
needed. A future version of this document will address this issue.
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