Support of Hostname and Sequencing in YANG Notifications

NETCONF Event Notifications and YANG-Push allow NETCONF servers and YANG-Push publishers to send notifications to a data collection. In the metadata of the event notification header, only the eventTime is present indicating at which time the notification message was published. For YANG-Push notifications, the subscription ID is added to the "push-update" and "push-change-update" notification messages allowing the YANG-Push receiver to map and recognize which Xpath or subtree is bound to the subscription. When the NETCONF event notification message is forwarded from the receiver to another system, such as a messaging system or a time series database, the transport context is lost since it is not part of the NETCONF event notification message metadata. Therefore, the downstream system is unable to associate the message to the publishing process (the exporting router), nor able to detect message loss or reordering. To correlate network data among different Network Telemetry planes as described in or among different YANG-Push subscription types as defined in , a reference to the node streaming the data is needed. This is essential for understanding the timely relationship among these different planes and YANG-Push subscription types. Today, network operators work around this impediment by preserving the transport source IP address and sequence numbers of the publishing process. However, this implies encoding this information in the NETCONF event notification message which impacts the semantic readability of the message in the downstream system. On top of that, the transport source IP address might not represent the management IP address by which the YANG-Push publisher should be known. In other terms, the source-host , which is the "Address of the remote host for the session" might not be the management IP address. To overcome these issues, this document proposes extending the YANG notification header with a sysName, the node's fully-qualified domain name, and a sequence number as described in . This allows the downstream system to not only be able to identify from which network node, subscription, and time the message was published but also, the order of the published messages.

NETCONF Event Notifications and YANG-Push uses the same notification header that is described in . defines how these notifications should be encoded in JSON and CBOR. Besides the eventTime described in the following metadata objects are part of a notification message.

sysName:: Describes the node's fully-qualified domain name according to the 'sysName' object definition in from where the message was published from. This value is usually configured on the node by the administrator to uniquely identify the node in the network.

sequenceNumber:: Generates a unique sequence number for each published message by the publisher process. The number counts up at every published notification message as described in .

The Notification of NETCONF Event Notifications uses a XML structure that is defined in . also defines the capability "urn:ietf:params:netconf:capability:notification:1.0" allowing a NETCONF client to know that the NETCONF server supports sending notifications.

An implementation supporting this document extends the notification defined in adding a sysName and a sequenceNumber. Two more child nodes within the "notification" container are expected, representing the sysName and the sequenceNumber. An example showing this extension in XML is provided in :

2007-07-08T00:10:00Z example-router 187653 state Ethernet0 enabled ]]>

This document also adds a new capability to NETCONF so that the NETCONF server can notify the support of the sysName and sequenceNumber to the NETCONF client. When the NETCONF server supports this document, the following capability is advertised: The capability identifier is requested to IANA in . In the capability exchange between the NETCONF client and server, the server will announce this capability along with the supported capabilities by the server as shown in the example in .

urn:ietf:params:xml:ns:netconf:base:1.0 urn:ietf:params:netconf:capability:startup:1.0 urn:ietf:params:netconf:capability:notification:1.0 urn:ietf:params:netconf:capability:notification-sysname-sequence:1.0 4 ]]>

YANG-Push uses the same structure defined in . defines the structure using XML encoding. For other YANG encodings, describes how notifications should be encoded in JSON and CBOR.

An implementation supporting this document extends the notification defined in adding a sysName and a sequenceNumber. Two more child nodes within the "notification" root container are expected, representing the sysName and the sequenceNumber. provides an example of a "push-update" notification with the sysName and sequenceNumber. This examples is encoded in XML .

<notification xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0"> <eventTime>2023-02-04T16:30:11.22Z</eventTime> <sysName xmlns="urn:ietf:params:xml:ns:yang:ietf-notification-sequencing"> example-router </sysName> <sequenceNumber xmlns="urn:ietf:params:xml:ns:yang:ietf-notification-sequencing"> 187653 </sequenceNumber> <push-update xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-push"> <id>1011</id> <datastore-contents> <interfaces xmlns="urn:ietf:params:xml:ns:yang:ietf-interfaces"> <interface> <name>eth0</name> <oper-status>up</oper-status> </interface> </interfaces> </datastore-contents> </push-update> </notification> When the notifcation is encoded using JSON , the sysName and the sequenceNumber are encoded at root container. An example is shown in .

{ "ietf-notification:notification": { "eventTime": "2023-02-10T08:00:11.22Z", "ietf-notification-sequencing:sysName":"example-router", "ietf-notification-sequencing:sequenceNumber": 187653, "ietf-yang-push:push-update": { "id": 1011, "datastore-contents": { "ietf-interfaces:interfaces": [ { "interface": { "name": "eth0", "oper-status": "up" } } ] } } } } When the notification is encoded in CBOR , the sysName and the sequenceNumber are encoded at root container. An example is shown in using CBOR diagnostic notation from .

YANG-related system capabilites can be discovered by subscribing to the datastore defined in . This document augments the "ietf-notification-capabilities" defined in so that the YANG-Push receiver can learn the capabilities defined in this documents throught the datastore. The definition of this YANG augmentation is specified in .

This "ietf-notification-sequencing" YANG module augments the "ietf-notification" YANG module specified in Section 5 of adding the sysName and the sequenceNumber leaves and augments "ietf-notification-capabilities" defined in to add a system level capability.

The following is the YANG tree diagram for the "ietf-notification" structure:

The following YANG tree diagram is the full tree of the "ietf-notification-capabilities" YANG model:

/yanglib:yang-library/datastore/name | +--ro per-node-capabilities* [] | +--ro (node-selection)? | | +--:(node-selector) | | +--ro node-selector? | | nacm:node-instance-identifier | +--ro notc:subscription-capabilities | +--ro notc:max-nodes-per-update? uint32 | +--ro notc:periodic-notifications-supported? | | notification-support | +--ro (notc:update-period)? | | +--:(notc:minimum-update-period) | | | +--ro notc:minimum-update-period? uint32 | | +--:(notc:supported-update-period) | | +--ro notc:supported-update-period* uint32 | +--ro notc:on-change-supported? | | notification-support {yp:on-change}? | +--ro notc:minimum-dampening-period? uint32 | | {yp:on-change}? | +--ro notc:supported-excluded-change-type* union | {yp:on-change}? +--ro notc:subscription-capabilities +--ro notc:max-nodes-per-update? uint32 +--ro notc:periodic-notifications-supported? | notification-support +--ro (notc:update-period)? | +--:(notc:minimum-update-period) | | +--ro notc:minimum-update-period? uint32 | +--:(notc:supported-update-period) | +--ro notc:supported-update-period* uint32 +--ro notc:on-change-supported? | notification-support {yp:on-change}? +--ro notc:minimum-dampening-period? uint32 | {yp:on-change}? +--ro notc:supported-excluded-change-type* union | {yp:on-change}? +--ro inotifseq:sysname-sequence-supported? notification-support {sysname-sequence}? ]]>

The "ietf-notification-sequencing" augments the "ietf-notification" and "ietf-notification-capabilities" YANG modules.

file "ietf-notification-sequencing@2023-05-29.yang" module ietf-notification-sequencing { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-notification-sequencing"; prefix inotifseq; import ietf-inet-types { prefix inet; reference "RFC 6991: Common YANG Data Types"; } import ietf-yang-types { prefix yang; reference "RFC 6991: Common YANG Data Types"; } import ietf-notification { prefix inotif; reference "draft-ahuang-netconf-notif-yang: NETCONF Event Notification YANG"; } import ietf-system-capabilities { prefix sysc; reference "RFC 9196: YANG Modules Describing Capabilities for Systems and Datastore Update Notifications"; } import ietf-notification-capabilities { prefix notc; reference "RFC 9196: YANG Modules Describing Capabilities for Systems and Datastore Update Notifications"; } import ietf-yang-structure-ext { prefix sx; reference "RFC 8791: YANG Data Structure Extensions"; } organization "IETF NETCONF (Network Configuration) Working Group"; contact "WG Web: WG List: Authors: Thomas Graf Jean Quilbeuf Alex Huang Feng "; description "Defines NETCONF Event Notification structure with the sysName and the sequenceNumber. Copyright (c) 2024 IETF Trust and the persons identified as authors of the code. All rights reserved. Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to the license terms contained in, the Revised BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info). This version of this YANG module is part of RFC XXXX; see the RFC itself for full legal notices."; revision 2023-06-30 { description "First revision"; reference "RFC XXXX: YANG Notifications Sequencing"; } feature sysname-sequence { description "This feature indicates that sysName and sequenceNumber are supported in notifications."; } typedef notification-support { type bits { bit config-changes { description "The publisher is capable of sending notifications for 'config true' nodes for the relevant scope and subscription type."; } bit state-changes { description "The publisher is capable of sending notifications for 'config false' nodes for the relevant scope and subscription type."; } } description "Redefition of the type 'notification-support' from 'ietf-notification-capabilities' module to be reusable in other YANG modules. Type for defining whether 'on-change' or 'periodic' notifications are supported for all data nodes, 'config false' data nodes, 'config true' data nodes, or no data nodes. The bits config-changes or state-changes have no effect when they are set for a datastore or for a set of nodes that does not contain nodes with the indicated config value. In those cases, the effect is the same as if no support was declared. One example of this is indicating support for state-changes for a candidate datastore that has no effect."; reference "RFC XXXX: YANG Notifications Sequencing RFC 9196: YANG Modules Describing Capabilities for Systems and Datastore Update Notifications"; } sx:augment-structure "/inotif:notification" { leaf sysName { type inet:host; mandatory true; description "Fully-qualified domain name of the node according to [RFC1213]. This value is usually configured on the node by the administrator to uniquely identify the node in the network."; } leaf sequenceNumber { type yang:counter32; mandatory true; description "Generates a unique sequence number for each published message by the publisher process. The number counts up at every published notification message as described [RFC9187]."; } } augment "/sysc:system-capabilities/notc:subscription-capabilities" { description "Add system level capabilities"; leaf sysname-sequence-supported { if-feature "sysname-sequence"; type notification-support; description "Specifies whether the publisher supports exporting a sysName and a sequenceNumber in notifications."; reference "RFC XXXX: YANG Notifications Sequencing"; } } } ]]>



    
      Note to the RFC-Editor: Please remove this section before
      publishing.

      
        6WIND implemented this document for a YANG-Push publisher on  UDP-based Transport for
        Configured Subscriptions in their VSR platform.
      
    

    
      The security considerations for the NETCONF Event notifications are
      described in . This documents adds no additional
      security considerations.
    

    
      
        This document registers the following URIs in the "IETF XML
        Registry" :

        
          
            
          
        
      

      
        This document registers the following YANG modules in the "YANG
        Module Names" registry :

        
          
        
      

      
        This document registers the following NETCONF capability in the
        "Network Configuration Protocol (NETCONF) Capability URNs"
        registry:

        
          
        
      
    

    
      
        In order to allow data correlation among BGP Monitoring Protocol
        (BMP)  and YANG-Push, the same hostname value
        should be used as described in 
        for the information TLV in the init BMP message type.
      
    

    
      The authors would like to thank Rob Wilton, Nick Corran, Pierre
      Francois, Benoit Claise, Ahmed Elhassany and Ignacio Dominguez
      Martinez-Casanueva for their review and valuable comments.