| NETCONF | E. Voit |
| Internet-Draft | Cisco Systems |
| Intended status: Standards Track | A. Bierman |
| Expires: April 1, 2018 | YumaWorks |
| A. Clemm | |
| Huawei | |
| T. Jenkins | |
| Cisco Systems | |
| September 28, 2017 |
Notification Message Headers and Bundles
draft-ietf-netconf-notification-messages-00
This document specifies transport independent capabilities for messages transporting event notifications and YANG datastore update records. Included are:
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Mechanisms to support subscription to event notifications and yang datastore push are being defined in [subscribe] and [yang-push]. Work on those documents have shown that existing YANG notifications described in [RFC7950] section 7.16 do not expose some useful transport independent capabilities that application developers are requesting. Communicating information on the following objects should not require knowledge of the underlying transport:
The document describes information elements needed for the functions above. It also provides YANG Notifications for sending messages containing bone or more events and/or update records to a receiver.
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.
Definitions of Notification, Event, Event Notification, Receiver, and Subscription are defined in [subscribe].
There are a number of transport independent headers which should have common definition across applications. These include:
Many objects may be placed within a notification. However only a certain subset these objects are of potential use to networking layers prior the notification being interpreted by some receiving application layer process. By exposing this object information as part of a header, and by using standardized object names, it becomes possible for this object information to be leveraged in transit.
The objects defined in the previous section effectively become well-known objects where, if in the header, may act as supplemental information in communications between two devices. These well-known header fields are encapsulated within a dedicated subtree which leads off the notification message. This allows header objects to be easily be decoupled, stripped, and processed separately.
Typically sequence of information in YANG models is irrelevant. But as part of a transported notification, It is useful to sequence these header objects so that processing is as efficient as possible. This allows the handling or discarding of uninteresting notifications quickly.
Below is are record objects contents would include the objects presented in the section above. The proper way this message would be generated would be to look for the well known object names and place them in the header. All other would be placed in the notification record contents. (Note: are there any of these we should rather duplicate than move?)
+---n notification-message
+--ro notification-message-header
| +--ro record-time yang:date-and-time
| +--ro record-type? notification-record-format
| +--ro subscription-id* uint32
| +--ro record-id? uint32
| +--ro observation-domain-id? string
| +--ro notification-id? uint32
| +--ro notification-time? yang:date-and-time
| +--ro previous-notification-id? uint32
| +--ro dscp? inet:dscp
| +--ro message-generator-id? string
| +--ro signature? string
+--ro receiver-record-contents?
An actual instance of a notification might look like:
<notification
xmlns="urn:ietf:params:xml:ns:netmod:notification:2.0">
<notification-message-header>
<record-time>
2017-02-14T00:00:02Z
</record-time>
<record-type>
yang-patch
</record-type>
<subscription-identifier>
823472
</subscription-identifier>
<notification-time>
2017-02-14T00:00:05Z
</notification-time>
<notification-identifier>
456
</notification-identifier>
<previous-notification-identifier>
567
</previous-notification-identifier>
<signature>
lKIo8s03fd23.....
</signature>
</notification-message-header>
<datastore-changes>
...(yang patch here)...
</datastore-changes>
</notification>
In many implementations, it may be inefficient to transport every notification independently. Instead, scale and processing speed can be improved by placing multiple notifications into one transportable bundle.
When this is done, one additional header field becomes valuable. This is the "record-count" which would tally the quantity of records which make up the contents of the bundle.
The format of a bundle would look as below. When compared to the unbundled notification, note that the headers have been split so that one set of headers associated with the notification occur once at the beginning of the message, and additional record specific headers which occur before individual records.
+---n bundled-notification-message
+--ro bundled-notification-message-header
| +--ro notification-id? uint32
| +--ro notification-time yang:date-and-time
| +--ro previous-notification-id? uint32
| +--ro dscp? inet:dscp
| +--ro message-generator-id? string
| +--ro signature? string
| +--ro record-count? uint16
+--ro notification-records*
+--ro notification-record-header
| +--ro record-time yang:date-and-time
| +--ro record-type? notification-record-format
| +--ro subscription-id* uint32
| +--ro record-id? uint32
| +--ro observation-domain-id? string
+--ro receiver-record-contents?
An actual instance of a bundled notification might look like:
<notification
xmlns="urn:ietf:params:xml:ns:netmod:notification:2.0">
<bundled-notification-message-header>
<notification-time>
2017-02-14T00:00:05Z
</notification-time>
<notification-identifier>
456
</notification-identifier>
<previous-notification-identifier>
567
</previous-notification-identifier>
<signature>
lKIo8s03fd23...
</signature>
<record-count>
2
</record-count>
</bundled-notification-message-header>
<notification-record>
<notification-record-header>
<record-time>
2017-02-14T00:00:02Z
</record-time>
<record-type>
yang-patch
</record-type>
<subscription-identifier>
823472
</subscription-identifier>
</notification-record-header>
<notification
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
<datastore-changes>
...(yang patch here)...
</datastore-changes>
</notification>
</notification-record>
<notification-record>
...(record #2)...
</notification-record>
</notification>
<CODE BEGINS> file "ietf-notification-messages.yang"
module ietf-notification-messages {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-notification-messages";
prefix nm;
import ietf-yang-types {
prefix yang;
}
import ietf-inet-types {
prefix inet;
}
organization "IETF";
contact
"WG Web: <http://tools.ietf.org/wg/netconf/>
WG List: <mailto:netconf@ietf.org>
WG Chair: Mahesh Jethanandani
<mailto:mjethanandani@gmail.com>
WG Chair: Mehmet Ersue
<mailto:mehmet.ersue@nokia.com>
Editor: Eric Voit
<mailto:evoit@cisco.com>
Editor: Alexander Clemm
<mailto:ludwig@clemm.org>
Editor: Tim Jenkins
<mailto:timjenki@cisco.com>
Editor: Andy Bierman
<mailto:andy@yumaworks.com>";
description
"This module contains conceptual YANG specifications for
notification messages with well known header objects.";
revision 2017-04-25 {
description
"This module includes definitions for two new yang
notification message objects:
(a) a message format including the definitions for common header
information prior to notification payload.
(b) a message format allowing the bundling of multiple
notifications within it";
reference
"draft-voit-netconf-notification-messages-01";
}
/*
* IDENTITIES
*/
/* Identities for notification record types */
identity notification-record-format {
description
"Base identity to represent a different formats for notification
records.";
}
identity system-event {
base notification-record-format;
description
"System XML event";
}
identity yang-datastore {
base notification-record-format;
description
"yang data node / tree extract";
}
identity yang-patch {
base notification-record-format;
description
"yang patch record";
}
identity syslog-entry {
base notification-record-format;
description
"Unstructured syslog entry.";
}
identity alarm {
base notification-record-format;
description
"Alarm (perhaps link draft-sharma-netmod-fault-model-01 for more
info)";
}
/*
* TYPEDEFs
*/
typedef notification-record-format {
type identityref {
base notification-record-format;
}
description
"Type of notification record";
}
/*
* GROUPINGS
*/
grouping notification-message-header {
description
"Header information included with a notification.";
leaf notification-id {
type uint32;
description
"unique id for a notification which may go to one or many
receivers.";
}
leaf notification-time {
type yang:date-and-time;
description
"time the notification was generated prior to being sent to
transport.";
}
leaf previous-notification-id {
type uint32;
description
"Notification id previously sent by publisher to a specific
receiver (allows detection of loss/duplication).";
}
leaf dscp {
type inet:dscp;
default "0";
description
"The push update's IP packet transport priority. This is made
visible across network hops to receiver. The transport
priority is shared for all receivers of a given
subscription.";
}
leaf message-generator-id {
type string;
description
"Software entity which created the notification message (e.g.,
linecard 1).";
}
leaf signature {
type string;
description
"Any originator signing of the contents of a notification
message. This can be useful for originating applications to
verify record contents even when shipping over unsecure
transport.";
}
}
grouping notification-record-header {
description
"Common informational objects which might help a receiver
interpret the meaning, details, and importance of an event
notification.";
leaf record-time {
type yang:date-and-time;
mandatory true;
description
"Time the system recognized the occurrence of an event.";
}
leaf record-type {
type notification-record-format;
description
"Describes the type of payload included. This is turn allow
the interpretation of the record contents.";
}
leaf-list subscription-id {
type uint32;
description
"Id of the subscription which led to the notification being
generated.";
}
leaf record-id {
type uint32;
description
"Identifier for the notification record.";
}
leaf observation-domain-id {
type string;
description
"Software entity which created the notification record (e.g.,
process id).";
}
}
/*
* NOTIFICATIONS
*/
notification notification-message {
description
"Notification message to a receiver containing only one event.";
container notification-message-header {
description
"delineates header info from notification messages for easy
parsing.";
uses notification-record-header;
uses notification-message-header;
}
anydata receiver-record-contents {
description
"Non-header info of what actually got sent to receiver after
security filter. (Note: Possible to have extra process
encryption.)";
}
}
notification bundled-notification-message {
description
"Notification message to a receiver containing many events,
possibly relating to independent subscriptions.";
container bundled-notification-message-header {
description
"Delineates header info from notification messages for easy
parsing.";
uses notification-message-header {
refine notification-time {
mandatory true;
}
}
leaf record-count {
type uint16;
description
"Quantity of events in a bundled-notification-message
for a specific receiver. This value is per receiver in
case an entire notification record is filtered out.";
}
}
list notification-records {
description
"Set of messages within a notification to a receiver.";
container notification-record-header {
description
"delineates header info from notification messages for easy
parsing.";
uses notification-record-header;
}
anydata receiver-record-contents {
description
"Non-header info of what actually got sent to receiver after
security filter. (Note: Possible to have extra process
encryption.)";
}
}
}
}
<CODE ENDS>
More needs to be thought through here, as this adds additional information onto notifications, the security implications shouldn't be singificantly beyond those from [subscribe] other than ensuring that data plane devices can accomplish the necessary content filtering despite the potential of a new level of header being applied.
| [RFC2119] | Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997. |
| [subscribe] | Voit, E., Clemm, A., Gonzalez Prieto, A., Prasad Tripathy, A. and E. Nilsen-Nygaard, "Custom Subscription to Event Notifications", September 2017. |
| [initial-version] | Voit, E., Bierman, A., Clemm, A. and T. Jenkins, "Custom Subscription to Event Notifications", February 2017. |
| [RFC7950] | Bjorklund, M., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016. |
| [yang-push] | Clemm, A., Voit, E., Gonzalez Prieto, A., Prasad Tripathy, A. and E. Nilsen-Nygaard, "Subscribing to YANG datastore push updates", April 2017. |
(To be removed by RFC editor prior to publication)
We need to define the ways to invoke and configure the capability within an originating device. This includes defining what header types are selected. This also includes knowning the header types which can be supported by a receiver.
We need to do a lot more to discuss transport efficiency implications.
(This appendix was in a previous iteration of this draft. It has been removed as unlikely to be seen in an implementation. It is being kept in for discussion purposes.)
It is also possible that that external entities might want to query message information after it has been sent. And therefore it is possible that an administrator would like to examine the contents of notifications via random access using a YANG model rather that Syslog. There could be several values in such random access. These include:
If such random access is needed, it is possible to extend the YANG model data model document to enable random access to the information. A cut at what this might look like can be seen in [initial-version]