| Netconf | B. Lengyel |
| Internet-Draft | Ericsson |
| Intended status: Standards Track | A. Clemm |
| Expires: December 15, 2018 | Huawei USA |
| June 13, 2018 |
YangPush Notification Capabilities
draft-lengyel-netconf-notification-capabilities-01
This document proposes a YANG module that allows a YANG server to specify for which data nodes it will send "YANG Datastore Subscription" on-change notifications. It also proposes to use YANG Instance Data to document this information in implementation time.
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Copyright (c) 2018 IETF Trust and the persons identified as the document authors. All rights reserved.
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The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.
On-change Notification Capability: The capability of the YANG server to send on-change notifications on the change of the value for a specific data node.
Implementation-time information: Information about the YANG server's behavior that is made available during the implementation of the server, available from a source other then a running Yang server .
Rutime-information: Information about the YANG server's behavior that is available from the running YANG server via a protocol like NETCONF, RESTCONF or HTTPS.
As defined in [I-D.ietf-netconf-yang-push] a YANG server may allow clients to subscribe to updates from a datastore and subsequently push such update notifications to the client. Notifications may be sent periodically or on-change (more or less immendiately after each change).
In some cases, a publisher supporting on-change notifications will not be able to push updates for some object types on-change. Reasons for this might be that the value of the datastore node changes frequently (e.g. in-octets counter), that small object changes are frequent and meaningless (e.g., a temperature gauge changing 0.1 degrees), or that the implementation is not capable of on-change notification for a particular object. In those cases, it will be important for client applications to have a way to identify for which objects on-change notifications are supported and for which ones they are not supported.
Faced with the reality that support for on-change notification does not mean that such notifications will be sent for any specific data node, client/management applications can not rely on the on-change functionality unless the client has some means to identify for which objects on-change notifications are supported and for which ones they are not supported. YANG models are meant to be used as an interface contract. Without identification of data nodes supporting on-change, today this contract only states the YANG server may (or may not) send on-change notifications for a data node specified in a YANG module.
This document proposes a YANG module that allows a client to identify which data nodes support on-change notification, removing the uncertainty for on-change notifications.
On-change Notification Capability information will be needed both in implementation-time and run-time.
Run-time information is needed
Implementation time information is needed by Network Management System (NMS) implementers. During NMS implementation for any functionality that depends on the notifications the information about on change notification capability is needed. If the information is not available early in some document, but only as instance data from the network node, the NMS implementation will be delayed, because it has to wait for the network node to be ready. Also assuming that all NMS implementers will have a correctly configured network node available to retrieve data from, is very expensive. (An NMS may handle dozens of network node types.) Often a fully functional NMS is a requirement for introducing a new network node type into a network, so delaying the NMS effectively delays the availability of the network node as well.
Implementation time information is needed by system integrators. System integrators will need information about on change notification capability early. When introducing a network node type into their network operators often need to integrate the node type into their own management system. The NMS may have management functions that depend on on-change notifications. The network operator needs to plan his management practices and NMS implementation before he even decides to buy the specific network node type. Moreover the decision to buy the node type sometimes depends on these management possibilities.
As described above a number of stakeholders need information about the on change notification capability both in implementation and run-time. It is a goal to provide this information in a format that is [I-D.ietf-netconf-rfc7895bis]. For each implemented YANG Module listed in the ietf-yang-library there is a default notification capability separately for config false and config true data nodes. There is also an on-change-notification-capability list containing a potentially different true/false notification capability for any data nodes in the schema tree. Unless a node is in the list with a specific capability value, it inherits its on-change-notification-capability from its parent in the data tree, or from the relevant default values.
The YANG module ietf-notification-capabilities is defined to provide information about the on-change notification capabilities. It is defined as an extension to the ietf-yang-library module
The instance information SHALL be provided in two ways both following the ietf-notification-capabilities module:
If the information retrieved via Netconf/Restconf and the YANG Instance Data File conflict, the former MUST be considered authorative.
The following tree diagram [I-D.ietf-netmod-yang-tree-diagrams] provides an overview of the data model.
module: ietf-notification-capabilities
augment /yanglib:yang-library/yanglib:module-set:
+--ro notification-sent-for-config-default? boolean
+--ro notification-sent-for-state-default? boolean
+--ro on-change-notification-capability* [data-node-selector]
+--ro data-node-selector nacm:node-instance-identifier
+--ro on-change-notification-sent? boolean
<CODE BEGINS> file "ietf-notification-capabilities.yang"
module ietf-notification-capabilities {
yang-version 1.1;
namespace
"urn:ietf:params:xml:ns:yang:ietf-notification-capabilities";
prefix inc;
import ietf-yang-library {
prefix yanglib;
reference "rfc7895bis";
// at least revision 2018-xx-yy
}
import ietf-netconf-acm { prefix nacm; }
organization
"IETF NETCONF (Network Configuration) Working Group";
contact
"WG Web: <https://datatracker.ietf.org/wg/netconf/>
WG List: <mailto:netconf@ietf.org>
WG Chair: Kent Watsen
<mailto:kwatsen@juniper.net>
WG Chair: Mahesh Jethanandani
<mailto:mjethanandani@gmail.com>
Editor: Balazs Lengyel
<mailto:balazs.lengyel@ericsson.com>";
description "This module augments the ietf-yang-library to
specify per module for which data nodes will the YANG server
send on-change notifications.
On-change notification capability is marked as true or false.
This marking is inherited from the parent down the data tree
unless explicitly marked otherwise.
On-change notifications SHALL be sent for a config=true
data node if one of the following is true:
- it is specified in the on-change-notification-capability
list and has a on-change-notification-sent value true or
- notifications are sent for its parent data node and it is
not specified in the on-change-notification-capability list or
- if it is a top level data-node and is not specified in the
on-change-notification-capability list and the
notification-sent-for-config-default is true.
On-change notifications SHALL be sent for a config=false
data node if one of the following is true:
- it is specified in the on-change-notification-capability
list and has an on-change-notification-sent value true or
- notifications are sent for its parent data node
which is also config=false and it is
not specified in the on-change-notification-capability list or
- if it is a top level data-node or has a config=true parent
data node and is not specified in the
on-change-notification-capability list and the
notification-sent-for-state-default is true.
";
revision 2018-06-12 {
description "Initial version";
reference
"RFC XXX: YangPush Notification Capabilities";
}
augment /yanglib:yang-library/yanglib:module-set/yanglib:module {
description "Extends the ietf-yang-library module with
on-change-notification-capability information";
leaf notification-sent-for-config-default {
type boolean;
default true;
description "Specifies the default value for this module's
top level configuration data nodes for the
on-change-notification-sent capability.";
}
leaf notification-sent-for-state-default {
type boolean;
default false;
description "Specifies the default value for this module's
top level state data nodes for the
on-change-notification-sent capability.";
}
list on-change-notification-capability {
key data-node-selector ;
description "A list of data nodes that have the
on-change-notification-capability specifically defined.
Should be used when specific data nodes support
on-change notification in a module/subtree that
generally does not support it or when some data nodes
do not support the notification in a module/subtree
that generally supports on-change notifications.";
leaf data-node-selector {
type nacm:node-instance-identifier;
description data-node-selector;
}
leaf on-change-notification-sent {
type boolean;
description "Specifies whether the YANG server will
send on-change notifications for the selected
data nodes.";
}
}
}
}
<CODE ENDS>
The YANG module defined in this document is designed to be accessed via YANG based management protocols, such as NETCONF and RESTCONF. Both of these protocols have mandatory-to- implement secure transport layers (e.g., SSH, TLS) with mutual authentication.
The NETCONF access control model (NACM) provides the means to restrict access for particular users to a pre-configured subset of all available protocol operations and content.
This document registers one URI in the IETF XML registry [RFC3688]. Following the format in [RFC3688], the following registrations are requested:
URI: urn:ietf:params:xml:ns:yang:ietf-notification-capabilities Registrant Contact: The NETCONF WG of the IETF. XML: N/A, the requested URI is an XML namespace.
This document registers one YANG module in the YANG Module Names registry [RFC7950]. Following the format in [RFC7950], the the following registrations are requested:
name: ietf-notification-capabilities namespace: urn:ietf:params:xml:ns:yang:ietf-notification-capabilities prefix: inc reference: RFC XXXX
| [I-D.ietf-netconf-rfc7895bis] | Bierman, A., Bjorklund, M., Schoenwaelder, J., Watsen, K. and R. Wilton, "YANG Library", Internet-Draft draft-ietf-netconf-rfc7895bis-06, April 2018. |
| [I-D.ietf-netconf-yang-push] | Clemm, A., Voit, E., Prieto, A., Tripathy, A., Nilsen-Nygaard, E., Bierman, A. and B. Lengyel, "YANG Datastore Subscription", Internet-Draft draft-ietf-netconf-yang-push-16, May 2018. |
| [I-D.lengyel-netmod-yang-instance-data] | Lengyel, B. and B. Claise, "YANG Instance Data Files and their use for Documenting Server Capabilities", Internet-Draft draft-lengyel-netmod-yang-instance-data-00, February 2018. |
| [RFC7950] | Bjorklund, M., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016. |
| [I-D.ietf-netmod-yang-tree-diagrams] | Bjorklund, M. and L. Berger, "YANG Tree Diagrams", Internet-Draft draft-ietf-netmod-yang-tree-diagrams-06, February 2018. |
| [RFC2119] | Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997. |
| [RFC3688] | Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004. |
| [RFC8174] | Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017. |
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