Support of Hostname and Sequencing in YANG Notifications

Status of This Memo

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Copyright Notice

Copyright (c) 2023 IETF Trust and the persons identified as the document authors. All rights reserved.¶

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Table of Contents

1. Introduction

[RFC5277] describes the NETCONF event notification header using a XML Schema. In the metadata of the event notification header, only the eventTime is present indicating at which time the notification message was published. For other encodings, the same schema is implemented using a YANG module in [I-D.ahuang-netconf-notif-yang]. Furthermore, in Section 3.7 of [RFC8641], the subscription ID is added to the "push-update" and "push-change-update" notification messages allowing to recognize to which xpath or sub-tree the node was subscribed to.¶

When the NETCONF event notification message is forwarded from the receiver to another system, such as a messaging system or a time series database where the message is stored, 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.¶

Today, network operators workaround this impediment by preserving the transport source IP address and sequence numbers of the publishing process. However, this implies that this information needs to be encoded 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 server should be known. In other terms, the source-host [RFC6470], which is the "Address of the remote host for the session" might not be the management IP address.¶

By extending the NETCONF Event Notification header with sysName, which could be an IP address or a DNS domain name, and a sequence number as described in [RFC9187], the downstream system is not only able to identify from which network node, subscription, and time the message was published but also, the order of the published messages.¶

To correlate network data among different Network Telemetry planes as described in Section 3.1 of [RFC9232] or among different YANG push subscription types defined in Section 3.1 of [RFC8641], sysName describes from which network node the state change was observed or from when to when the data was accounted. This is essential for understanding the timely relationship among these different planes and YANG push subscription types.¶

2. Extend the NETCONF Event Notification Header

Besides the eventTime described in Section 2.2.1 of [RFC5277] the following metadata objects are part of a "push-update" and "push-change-update" notification message.¶

sysName:

Describes the hostname as specified in [RFC1213] from where the message was published from.¶

sequenceNumber:

Generates a unique sequence number as described in [RFC9187] for each published message.¶

Figure 1 provides an example of a "push-change-update" message with the sysName and sequenceNumber. This "push-change-update" message is encoded XML [W3C.REC-xml-20081126] over the Network Configuration Protocol (NETCONF) as per [RFC8640].¶

<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>

3. YANG Module for Event Notifications

module: ietf-notification-sequencing

  augment-structure /inotif:notification:
    +-- sysName           inet:host
    +-- sequenceNumber    yang:counter32

module: ietf-notification

  structure notification:
    +-- eventTime                   yang:date-and-time
    +-- inotifseq:sysName           inet:host
    +-- inotifseq:sequenceNumber    yang:counter32

<CODE BEGINS> file "ietf-notification-sequencing@2023-03-01.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-yang-structure-ext {
    prefix sx;
    reference
      "RFC 8791: YANG Data Structure Extensions";
  }

  organization "IETF NETCONF (Network Configuration) Working Group";
  contact
    "WG Web:   <http:/tools.ietf.org/wg/netconf/>
     WG List:  <mailto:netconf@ietf.org>

     Authors:  Thomas Graf
               <mailto:thomas.graf@swisscom.com>
               Jean Quilbeuf
               <mailto:jean.quilbeuf@huawei.com>
               Alex Huang Feng
               <mailto:alex.huang-feng@insa-lyon.fr>";

  description
    "Defines NETCONF Event Notification structure with the sysName and
    the sequenceNumber.

    Copyright (c) 2023 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 2023-03-01 {
    description
      "First revision";
    reference
      "RFC XXXX: YANG Notifications Sequencing";
  }

  sx:augment-structure "/inotif:notification" {
    leaf sysName {
      type inet:host;
      mandatory true;
      description
        "IP address or a DNS domain name from the server from which
        the message was published.";
    }
    leaf sequenceNumber {
      type yang:counter32;
      mandatory true;
      description
        "Unique sequence number as described in [RFC3339] for each
        published message.";
    }
  }
}

<CODE ENDS>

4. Security Considerations

The security considerations for the NETCONF Event notifications are described in [RFC5277]. This documents adds no additional security considerations.¶

5. IANA Considerations

  URI: urn:ietf:params:xml:ns:yang:ietf-notification-sequencing
  Registrant Contact: The IESG.
  XML: N/A; the requested URI is an XML namespace.

  name: ietf-notification-sequencing
  namespace: urn:ietf:params:xml:ns:yang:ietf-notification-sequencing
  prefix: inotifseq
  reference: RFC XXXX

6. Operational Considerations

7. Acknowledgements

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.¶

Authors' Addresses