NETCONF A. Huang-Feng Internet-Draft Deutsche Telekom Intended status: Standards Track P. Francois Expires: 30 January 2027 INSA-Lyon T. Zhou Huawei T. Graf Swisscom P. Lucente NTT 29 July 2026 UDP-based Transport for Configured Subscriptions draft-ietf-netconf-udp-notif-26 Abstract This document describes a UDP-based transport for YANG notifications to collect data from network nodes within a controlled environment. A shim header is defined to facilitate the data streaming directly from a publishing process on a network device to telemetry receivers. Such a design enables higher frequency updates and less performance overhead on publisher and receiver processes compared to already established notification mechanisms. A YANG data model is also defined for management of the described UDP-based transport. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on 30 January 2027. Copyright Notice Copyright (c) 2026 IETF Trust and the persons identified as the document authors. All rights reserved. Huang-Feng, et al. Expires 30 January 2027 [Page 1] Internet-Draft UDP-Notif July 2026 This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. UDP-Based Transport . . . . . . . . . . . . . . . . . . . . . 5 3.1. Design Overview . . . . . . . . . . . . . . . . . . . . . 6 3.2. Format of the UDP-Notif Message Header . . . . . . . . . 7 3.3. Data Encoding . . . . . . . . . . . . . . . . . . . . . . 9 4. Options . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 4.1. Segmentation Option . . . . . . . . . . . . . . . . . . . 10 5. Applicability . . . . . . . . . . . . . . . . . . . . . . . . 12 5.1. Congestion Control . . . . . . . . . . . . . . . . . . . 12 5.2. Message Size . . . . . . . . . . . . . . . . . . . . . . 13 5.3. Reliability . . . . . . . . . . . . . . . . . . . . . . . 14 5.4. Checksum . . . . . . . . . . . . . . . . . . . . . . . . 14 6. Secured layer for UDP-Notif . . . . . . . . . . . . . . . . . 14 6.1. Session Lifecycle . . . . . . . . . . . . . . . . . . . . 15 6.1.1. DTLS Session Initiation . . . . . . . . . . . . . . . 15 6.1.2. Publish Data . . . . . . . . . . . . . . . . . . . . 15 6.1.3. Session Termination . . . . . . . . . . . . . . . . . 16 6.1.4. DTLS Fragmentation . . . . . . . . . . . . . . . . . 16 7. A YANG Data Model for Management of UDP-Notif . . . . . . . . 17 7.1. YANG Module for configuring UDP-Notif . . . . . . . . . . 17 7.2. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 19 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23 8.1. UDP-Notif Protocol Registry Group . . . . . . . . . . . . 23 8.1.1. UDP-Notif Media Types Registry . . . . . . . . . . . 23 8.1.2. UDP-Notif Option Types Registry . . . . . . . . . . . 24 8.1.3. UDP-Notif Header Version Registry . . . . . . . . . . 24 8.2. URI . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 8.3. YANG Module Name . . . . . . . . . . . . . . . . . . . . 25 9. Implementation Status . . . . . . . . . . . . . . . . . . . . 26 9.1. Open Source Publisher . . . . . . . . . . . . . . . . . . 26 9.2. Open Source Receiver Library . . . . . . . . . . . . . . 26 9.3. Pmacct Data Collection . . . . . . . . . . . . . . . . . 26 9.4. Huawei VRP . . . . . . . . . . . . . . . . . . . . . . . 26 9.5. 6WIND VSR . . . . . . . . . . . . . . . . . . . . . . . . 26 9.6. Cisco IOS XR . . . . . . . . . . . . . . . . . . . . . . 26 10. Operational Considerations . . . . . . . . . . . . . . . . . 27 Huang-Feng, et al. Expires 30 January 2027 [Page 2] Internet-Draft UDP-Notif July 2026 10.1. ICMP Error Handling Considerations . . . . . . . . . . . 27 11. Security Considerations . . . . . . . . . . . . . . . . . . . 27 12. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 29 13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 29 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 29 14.1. Normative References . . . . . . . . . . . . . . . . . . 29 14.2. Informative References . . . . . . . . . . . . . . . . . 32 Appendix A. UDP-Notif Examples . . . . . . . . . . . . . . . . . 34 A.1. Configuration for UDP-Notif transport with DTLS disabled . . . . . . . . . . . . . . . . . . . . . . . . 35 A.2. Configuration for UDP-Notif transport with DTLS enabled . . . . . . . . . . . . . . . . . . . . . . . . . 36 A.3. YANG Push message with UDP-Notif transport protocol . . . 38 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 39 1. Introduction The mechanism to support a subscription of a continuous and customized stream of updates from a YANG datastore [RFC8342] is defined in Subscribed Notifications [RFC8639] and YANG-Push [RFC8641]. Subscribed Notifications [RFC8639] separate the management and control of subscriptions from the transport used to deliver the data. Three transport mechanisms, namely NETCONF transport [RFC8640], RESTCONF transport [RFC8650], and HTTPS transport [I-D.ietf-netconf-https-notif] were defined for such notification messages. While powerful in their features, and general in their architecture, the currently available transport mechanisms need to be complemented to support data publications at high frequency with low overhead used within a controlled environment such as management networks. This is important for network nodes that feature a distributed architecture with sparse resources on components specialized for packet forwarding. The currently available transports are TCP-based requiring the maintenance of connections, states and retransmissions, which is not necessary for high-frequency continuous notification content, typically published directly from network processors on line cards. This document specifies a transport option for Configured Subscriptions as defined in Section 2.5 of [RFC8639] that leverages UDP. Specifically, it facilitates the distributed data collection mechanism described in [I-D.ietf-netconf-distributed-notif]. In the case of publishing from multiple network processors on multiple line cards, centralized designs require data to be internally forwarded from those network processors to the push server, presumably on a Huang-Feng, et al. Expires 30 January 2027 [Page 3] Internet-Draft UDP-Notif July 2026 route processor, which then combines the individual data items into a single consolidated stream. The centralized data collection mechanism can result in a performance bottleneck, especially when large amounts of data are involved. What is needed is a mechanism that allows for directly publishing from multiple network processors on line cards, without passing them through an additional processing stage for internal consolidation. The UDP-based transport allows for such a distributed data publishing approach: * Firstly, a UDP approach reduces the burden of maintaining a large pool of active TCP connections at the receiver, notably in cases where it collects data from network processors on line cards from a large number of network nodes. * Secondly, as only connection state for DTLS and no retransmissions are needed for notifications and its segments, UDP encapsulation could be implemented by the hardware of the publisher, which further improves performance. * Ultimately, such advantages allow for a larger data analysis feature set, as more voluminous, finer grained data sets can be streamed to the receiver. The transport described in this document can be used for transmitting notification messages over both IPv4 and IPv6. It is designed to be used in cases where packet loss is not a concern, such as the collection of statistical metrics that are exported periodically. This transport can be configured via NETCONF [RFC6241] or RESTCONF [RFC8040]. This document describes the notification mechanism. It is intended to be used in conjunction with [RFC8639], extended by [I-D.ietf-netconf-distributed-notif]. Additionally, this document defines a YANG data model for management of the UDP-based transport. The YANG module specified in this document is compliant with Network Management Datastore Architecture (NMDA) [RFC8342]. Section 3 details the notification mechanism and message format. Section 4 describes the use of options in the notification message header. Section 5 covers the applicability of the mechanism. Section 6 describes a mechanism to secure the protocol in open networks. Finally, Section 7 defines a YANG data model for management of the mechanism described in this document. Huang-Feng, et al. Expires 30 January 2027 [Page 4] Internet-Draft UDP-Notif July 2026 2. Terminology 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. The following terms are used as defined in Subscribed Notifications [RFC8639]: * Notification message * Subscription * Configured Subscription * Subscriber * Publisher * Receiver The following term is used as defined in [I-D.ietf-netconf-distributed-notif]: * Message Publisher ID This document defines the following term: * Message ID: identifier of a message transported by the UDP-Notif protocol. More details are presented in Section 3.2. 3. UDP-Based Transport The UDP-based transport specified in this document provides timely datagram delivery with support for segmentation and reassembly of YANG-Push notification messages over unicast UDP. It is designed to operate efficiently in controlled environments while providing robustness to packet loss, replay, off-path attacks, and path overload. Applicability considerations are provided in Section 5. Huang-Feng, et al. Expires 30 January 2027 [Page 5] Internet-Draft UDP-Notif July 2026 UDP-Notif defines a unidirectional transport association between a publisher and a receiver for the delivery of YANG-Push notification messages. Each UDP-Notif message consists of a UDP-Notif message header followed by a payload. When necessary, a message MAY be divided into multiple segments using the segmentation mechanism specified in this document. Each message or message segment is carried in a single unfragmented UDP datagram, and each UDP datagram contains exactly one UDP-Notif message or message segment. This section specifies the UDP-Notif transport behavior. Section 3.1 describes the general design of the solution. Section 3.2 specifies the UDP-Notif message format and Section 3.3 describes the encoding of the message payload. 3.1. Design Overview As specified in Section 2.6 of Subscribed Notifications [RFC8639], the content of a YANG notification is encapsulated in a notification message, which is then encapsulated and carried using a transport protocol. Figure 1 illustrates the structure of a UDP-Notif message: * The Message Header contains information that facilitates the message transmission before deserializing the notification message. * The Notification Message is the encoded content that is transported by the publication stream. The common encoding methods are listed in Section 3.2. The structure of the notification message is defined in Section 2.6 of Subscribed Notifications [RFC8639]. +--------+ +-------------+ +--------------+ | UDP | | Message | | Notification | | Header | | Header | | Message | +--------+ +-------------+ +--------------+ Figure 1: UDP-Notif Message Overview When a publisher starts streaming UDP-Notif messages, the first message generated by the publisher MUST be a separate "subscription- started" notification to indicate to the receiver that the stream has started flowing. Then, the notifications can be sent immediately without delay. Subscription state notifications, defined in Section 2.7 of [RFC8639], MUST be encapsulated in separate notification messages. Huang-Feng, et al. Expires 30 January 2027 [Page 6] Internet-Draft UDP-Notif July 2026 Note that receivers collecting UDP-Notif messages may not be already up and running when the configuration of the subscription takes effect on a monitored network node. A publisher SHOULD use a randomly selected ephemeral UDP source port for transmitting UDP-Notif messages, as recommended in Section 5.1 of [RFC8085]. A fixed source port MAY be configured through the YANG module defined in Section 7 when required for deployment-specific operational considerations. 3.2. Format of the UDP-Notif Message Header The UDP-Notif message header contains information that facilitates the message transmission between the publisher and the receiver before deserializing the notification message. The data format is shown in Figure 2. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-----+-+-------+---------------+-------------------------------+ | Ver |S| MT | Header Len | Message Length | +-----+-+-------+---------------+-------------------------------+ | Message Publisher ID | +---------------------------------------------------------------+ | Message ID | +---------------------------------------------------------------+ ~ Options ~ +---------------------------------------------------------------+ Figure 2: UDP-Notif Message Header Format The Message Header contains the following field: * Ver indicates the UDP-Notif protocol header version. The values are allocated by the IANA registry "UDP-Notif Header Version" (Section 8.1). The current header version number is 1. * S-flag represents the space of media type specified in the MT field. When S-flag is not set, MT represents the standard media types as defined in the IANA registry "UDP-Notif media types" (Section 8.1). When S-flag is set, MT represents a private space to be freely used for non-standard encodings. * MT is a 4-bit identifier that indicates the media type used for the notification message. When the S bit is not set, the following values apply: Huang-Feng, et al. Expires 30 January 2027 [Page 7] Internet-Draft UDP-Notif July 2026 - 0: Reserved, MUST NOT be used. - 1: application/yang-data+json [RFC8040] - 2: application/yang-data+xml [RFC8040] - 3: application/yang-data+cbor [RFC9254] * Header Len (8-bit) records the length of the message header in octets, including both the fixed header and the options. * Message Length (16-bit) records the total length of the UDP-Notif message within one UDP datagram, measured in octets, including the message header. When the notification message is segmented using the Segmentation Options defined in Section 4.1, the Message Length is the total length of the current UDP-Notif segment, not the length of the entire notification message. * Message Publisher ID is a 32-bit identifier defined in [I-D.ietf-netconf-distributed-notif]. This identifier is locally unique to the publisher node. It identifies the software process generating the stream of UDP-Notif messages and allow the disambiguation of an information source. Message unicity is obtained from the conjunction of the Message Publisher ID and the Message ID field. If Message Publisher ID unicity is not preserved through the collection domain, the source IP address of the UDP datagram MUST be used in addition to the Message Publisher ID to identify the information source. If a transport layer relay is used, Message Publisher ID unicity must be preserved through the collection domain. * The Message ID MUST start with a randomized number with the first message and increase monotonically by the publisher of UDP-Notif messages. A publisher MUST use different Message IDs for different messages generated with the same Message Publisher ID. Note that the main purpose of the Message ID is to reconstruct messages which are segmented using the segmentation option described in Section 4.1. The Message ID values MUST be incremented by one for successive messages originated with the same Message Publisher ID, so that message loss can be detected at data collection. When the last value (2^32-1) of Message ID has been reached, the Message ID wraps around and restarts at 0. * Options are a variable-length field in the TLV format. When the Header Length is larger than 12 octets, which is the length of the fixed header, Options TLVs follow directly after the fixed message header. Options are described in Section 4. Huang-Feng, et al. Expires 30 January 2027 [Page 8] Internet-Draft UDP-Notif July 2026 All the binary fields MUST be encoded in network byte order (big endian). 3.3. Data Encoding UDP-Notif message data can be encoded in XML, JSON or CBOR format. Additional encodings may be supported in the future. This can be accomplished by augmenting the subscription data model with additional identity statements used to refer to requested encodings. The new encoding can be registered in the IANA registry "UDP-Notif media types" following the procedure defined in Section 8.1. Subscribed Notifications [RFC8639] states that a transport MUST identify a default encoding. However, as per [Errata-6211], Subscribed Notifications does not require to define a default encoding. Private encodings can be used by enabling the S-flag of the header. When the S-flag is set, the value of the MT field is left to be defined and agreed upon by the users of the private encoding. The MT field allows for 16 private encodings when S-flag is set. The encoding of a message data is configured on a subscription basis and each subscription reference a receiver instance. Publishers MUST NOT be configured to send notification messages with more than one encoding to the same receivers. 4. Options All the options are defined with the format shown in Figure 3. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +---------------+---------------+-------------------------------- | Type | Length | Variable-length data ~ +---------------+---------------+-------------------------------- Figure 3: Generic Option Format * Type: 1-octet describing the option type. The values of the Type field are allocated by the IANA registry "UDP-Notif Option Types" (Section 8.1.2). * Length: 1-octet representing the total number of octets in the TLV, including the Type and Length fields. * Variable-length data: 0 or more octets of data. Huang-Feng, et al. Expires 30 January 2027 [Page 9] Internet-Draft UDP-Notif July 2026 When more than one option are used in a UDP-Notif header, the segmentation option defined in Section 4.1 MUST be placed first, if present. Placing the segmentation option first can simplify some implementations for both the publisher and the receiver, notably those assuming a fixed location for the segmentation option. Segmented messages where the segmentation option is not the first option MAY be discarded by the receiver. Receivers MUST discard UDP-Notif messages containing an option that the receiver does not support. Valid UDP-Notif options are defined by the IANA registry "UDP-Notif Option Types", as described in Section 8.1.2. 4.1. Segmentation Option The UDP payload length is limited to 65507 bytes (65535 - 28 bytes) for IPv4 and 65527 bytes (65535 - 8 bytes) for IPv6. Application- level headers will make the actual payload shorter. Even though binary encodings such as CBOR may not require more space than what is left, more voluminous encodings such as JSON and XML may suffer from this size limitation. Although IPv4 and IPv6 publishers can fragment outgoing notification messages exceeding their Maximum Transmission Unit (MTU), fragmented IP packets may not be desired for operational and performance reasons [BCP230]. Implementations MUST provide a configurable parameter to control the maximum size of a UDP-Notif segment. This parameter is defined as "max-segment-size" in the YANG module specified in Section 7.1. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +---------------+---------------+-----------------------------+-+ | Type | Length | Segment Number |L| +---------------+---------------+-----------------------------+-+ Figure 4: Segmentation Option Format The Segmentation Option (Figure 4) is included when the message content is segmented into multiple segments. Different segments of one message share the same Message ID. The fields of this option are as follows: * Type: indicates a Segmentation Option. The value is 1 for this option. * Length: indicates the length of this option, in octets. It MUST be set to 4 octets. Huang-Feng, et al. Expires 30 January 2027 [Page 10] Internet-Draft UDP-Notif July 2026 * Segment Number: 15-bit value indicating the sequence number of the current segment. The first segment of a segmented message has a segment number value of 0. The segment number cannot wrap around. * L: indicates whether the current segment is the last one of the message. When 0 is set, the current segment is not the last one. When 1 is set, the current segment is the last one, meaning that the total number of segments used to transport this message is the value of the current Segment Number + 1. Implementations MUST NOT use IP fragmentation to carry large messages. Implementations MUST either restrict the size of individual messages to a value that will not lead to IP fragmentation as per Section 5.2, or support the segmentation option. In the latter case, the parameter "max-segment-size" MUST be set so that the size of a UDP-Notif segment and the size of the IP layer together do not exceed the MTU of the egress interface. When a message has multiple options and is segmented, all the options MUST be present on the first segment. The rest of segmented messages MAY include all the options. The segmentation option MUST be placed first in all segments. The receiver MUST support the reception of unordered segments. The implementation of the receiver SHOULD provide an option to discard the received segments if, after some time, one of the segments is still missing and the reassembly of the message is not possible. No retransmission of lost segments are expected from the publisher. If the receiver collects a segment more than once, the implementation MUST drop the duplicate segment. To reassemble segmented UDP-Notif messages, the receiver should first identify UDP-Notif segments belonging to the same message by using the combination of the Message Publisher ID and Message ID. The receiver SHOULD wait for all the segments before starting the reassembly process. Once all the segments are collected, the receiver should create a new UDP-Notif header with the same Ver, S-flag, MT, Message Publisher ID and Message ID values. When UDP- Notif options other than the segmentation option are present in the first segment, these options need to be appended to the newly created UDP-Notif header. To reconstruct the original notification message, the receiver must concatenate the notification message of each UDP- Notif segments in an ascending order based on the Segment Number. The new concatenated notification message becomes the notification message of the newly created UDP-Notif message. The Header Length and Message Length are then updated accordingly. Huang-Feng, et al. Expires 30 January 2027 [Page 11] Internet-Draft UDP-Notif July 2026 5. Applicability This section provides an applicability for the UDP-Notif mechanism, following the UDP Usage Guidelines in Section 3 of [RFC8085]. According to Section 3.6 of [RFC8085], the mechanism falls in the category of UDP applications "designed for use within the network of a single network operator or on networks of an adjacent set of cooperating network operators, to be deployed in controlled environments". Thus, implementations SHALL follow the recommendations in place for such specific applications. We discuss recommendations on congestion control in Section 5.1, message size guidelines in Section 5.2, reliability considerations in Section 5.3 and checksum guidelines in Section 5.4. The main use case of the UDP-Notif mechanism is the collection of statistical metrics for accounting purposes, where potential loss is not a concern, but should however be reported (such as IPFIX Flow Records exported with UDP [RFC7011]). Such metrics are typically exported in a periodical subscription as described in Section 3.1 of [RFC8641]. 5.1. Congestion Control The above application falls into the category of applications performing transfer of large amounts of data. Thus, guidelines defined in Section 3.1.8 and 3.1.9 of [RFC8085] needs to be considered. The operator MUST enable Quality of Service (QoS) on the network between the publisher and receiver, pre-provision reserved capacity on a dedicated QoS class and ensure that the DSCP bits in the publisher, as defined in Section 2.3 of [RFC8639], are configured accordingly. It is RECOMMENDED to use the CS2 (Class Selector 2) as per Section 2.3 of [RFC4594] for OAM. This ensures that if connectivity is shared with other applications, either on connectivity dedicated to network management only or shared with applications unrelated to network management, YANG-Push notifications receive the proper forwarding treatment with an upper traffic volume boundary. As per Section 3 of [RFC8085], it is NOT RECOMMENDED to use the UDP- Notif mechanism over congestion-sensitive network paths. The only environments where UDP-Notif is expected to be used are managed networks. Implementations MUST NOT generate unbounded volumes of traffic by default and SHOULD require the users to explicitly configure such a mode of operation. Network operating systems implementing this specification are expected to have already a management and control Huang-Feng, et al. Expires 30 January 2027 [Page 12] Internet-Draft UDP-Notif July 2026 plane policing implementation that enforce application-specific rate limits on packet generation for processes running on the network node. For YANG-Push subscriptions, only reasonable values for periodic subscription intervals and dampening periods for on-change subscriptions SHOULD be configurable to prevent excessive traffic toward publisher and receiver systems and across intermediate networks. Burst mitigation through packet pacing is RECOMMENDED. Disabling burst mitigation should require the users to explicitly configure such a mode of operation. The receiver SHOULD monitor notification message delivery failures and expose these metrics to the application managing the YANG-Push subscription to the publisher. The application can use these metrics to adjust the subscription scope and streaming rate. A receiver can compare the value of the "sent-event-records" counter, as described in Section 2.8 of [RFC8639], with its own count of successfully delivered notification messages. If the publisher counter exceeds the receiver count, the receiver can infer that one or more notification messages were not successfully delivered. A notification message is considered not successfully delivered if one or more UDP-Notif Messages identified by the UDP-Notif Message ID are missing or if one or more required segments of a segmented UDP- Notif Message are missing. Duplicate segments received for an otherwise successfully reassembled notification message SHOULD be silently discarded and MUST NOT be counted as notification delivery failures. Likewise, UDP-Notif Messages or segments discarded because their Message ID falls outside the receiver acceptance window MUST NOT be counted as notification delivery failures. Implementations MAY maintain separate diagnostic counters for duplicate segments and for out-of-window messages, since these events can indicate duplication, misconfiguration, or an attack rather than network congestion. 5.2. Message Size Section 3.2 of [RFC8085] recommends not to rely on IP fragmentation for messages whose size result in IP packets exceeding the MTU along the path. The segmentation option of the current specification permits segmentation of the UDP-Notif message content without relying on IP fragmentation. The publisher and receiver MUST support Notification Messages of at least 96 kilobytes (KB), including any required segmentation and reassembly. Notification Messages larger than 96 KB SHOULD be Huang-Feng, et al. Expires 30 January 2027 [Page 13] Internet-Draft UDP-Notif July 2026 avoided, as they require additional segmentation. Excessive segmentation increases the likelihood that the loss of a single segment will prevent successful reassembly of the entire message. A receiver collecting segmented UDP-Notif Messages MUST support the reassembly of messages containing at least 64 segments. A receiver MAY support a larger configurable limit on the number of segments per message. Incomplete messages exceeding the configured limit MUST be discarded. A receiver collecting segmented UDP-Notif Messages SHOULD support a configurable reassembly timeout. The reassembly of segmented Notification Messages SHOULD occur within a 10 second time window and MUST NOT exceed 20 seconds. It is RECOMMENDED that publishers limit the number of segments to less than 64 to reduce the probability of losing an entire Notification Message due to segment loss and to limit resource consumption on the receiver. The generation of too many segments by a publisher can be used as an abuse to require computation resources for reassembling large messages at the receiver. 5.3. Reliability As per Section 3.3 of [RFC8085] guidelines, a receiver implementation MUST discard segments that were received but cannot be re-assembled as a complete message within a given amount of time. This time SHOULD be configurable. 5.4. Checksum As recommended in Section 3.4 of [RFC8085], implementations SHOULD generate and validate UDP checksums. For IPv6, Section 8.1 of [RFC8200] specifies that a UDP checksum must be computed when a UDP packet is originated by an IPv6 node. 6. Secured layer for UDP-Notif In unsecured networks, which are not authenticated and encrypted on layers below transport, UDP-Notif messages MUST be encrypted. This section presents a mechanism using DTLS [RFC6347][RFC9147] to secure UDP-Notif protocol. In addition to providing encryption, DTLS also ensures authentication and integrity protection, preventing attacks such as the injection of malicious segments or notifications. Implementations using DTLS to secure UDP-Notif messages MUST support DTLS 1.2 [RFC6347] or later, and SHOULD support DTLS 1.3 [RFC9147]. No DTLS extensions are defined in this document. Huang-Feng, et al. Expires 30 January 2027 [Page 14] Internet-Draft UDP-Notif July 2026 When this security layer is used, the publisher MUST always be a DTLS client, and the receiver MUST always be a DTLS server. The receivers MUST support accepting UDP-Notif Messages on the configured UDP port, but MAY be configurable to listen on a different port. The recommendations for UDP source port selection specified in Section 3.1 also apply when DTLS is used. 6.1. Session Lifecycle This section describes the lifecycle of UDP-Notif messages when they are encrypted using DTLS. 6.1.1. DTLS Session Initiation The publisher initiates a DTLS connection by sending a DTLS ClientHello to the Receiver. Implementations MAY disable the denial of service countermeasures defined by DTLS 1.2 and DTLS 1.3 if a given deployment can ensure that DoS attacks are not a concern. In DTLS 1.3 when the denial of service countermeasures are implemented, the Receiver responds with a DTLS HelloRetryRequest containing a stateless cookie. The publisher sends then a second DTLS ClientHello message containing the received cookie. Details can be found in Section 5.1 of [RFC9147]. When DTLS is implemented, the publisher MUST NOT send any UDP-Notif messages before the DTLS handshake has successfully completed. Implementations MUST NOT use the early data mechanism (also known as 0-RTT data) defined in DTLS 1.3 [RFC9147]. Implementations MUST follow recommendations defined by [BCP195]. If other cipher suites than the ones recommended by [BCP195] are used, then implementations MUST NOT negotiate a cipher suite that employs NULL integrity or authentication algorithms. Where confidentiality protection with DTLS is required, implementations must negotiate a cipher suite that employs a non-NULL encryption algorithm. 6.1.2. Publish Data When DTLS is used, all UDP-Notif messages MUST be published as DTLS "application_data". The guidance on avoiding IP fragmentation by using the Segmentation Option continues to apply. If a UDP-Notif message would result in an IP datagram exceeding the path MTU, after accounting for IP, UDP, and DTLS overhead, the message SHOULD be segmented using the Segmentation Option defined in Section 4.1 before being carried over DTLS. Huang-Feng, et al. Expires 30 January 2027 [Page 15] Internet-Draft UDP-Notif July 2026 The application data is defined by the following ABNF [RFC5234] expression: APPLICATION-DATA = UDP-NOTIF-MSG UDP-NOTIF-MSG is defined in Section 3. When the Segmentation Option defined in Section 4.1 is present, the UDP-NOTIF-MSG carries a single segment of a segmented UDP-Notif message. 6.1.3. Session Termination A Publisher (DTLS client) MUST close the associated DTLS connection when it does not expect to deliver further UDP-Notif messages. Before closing the connection, the publisher MUST send a DTLS close_notify alert. After sending close_notify, the publisher MAY close the DTLS connection without waiting for a close_notify from the Receiver. Upon receiving a close_notify from the publisher, a Receiver MUST respond with a close_notify if the DTLS connection is still open. When no data is received from a DTLS connection for an extended period of time, the Receiver (DTLS server) MAY close the connection. Implementations SHOULD use an inactivity timer with a default value of 10 minutes, unless an application-specific profile specifies otherwise. The Receiver MUST attempt to initiate an exchange of close_notify alerts with the publisher before closing the connection. Receivers that are unprepared to receive any more data MAY close the connection after sending the close_notify alert. Keeping a DTLS connection open after notifications are no longer expected results in unnecessary retention of DTLS state and transport resources, and therefore increases exposure to resource-exhaustion attacks. Although closure alerts are a component of TLS and so of DTLS, they, like all alerts, are not retransmitted by DTLS and so may be lost over an unreliable network. 6.1.4. DTLS Fragmentation DTLS 1.2 [RFC6347] and DTLS 1.3 [RFC9147] states that DTLS message may be fragmented into multiple DTLS records. A DTLS message carrying a UDP-Notif message SHOULD fit within a single datagram to avoid DTLS fragmentation. Implementations SHOULD account for DTLS overhead when determining the maximum UDP-Notif notification message size. Huang-Feng, et al. Expires 30 January 2027 [Page 16] Internet-Draft UDP-Notif July 2026 7. A YANG Data Model for Management of UDP-Notif 7.1. YANG Module for configuring UDP-Notif The YANG model described in Section 7.2 defines a new receiver instance for UDP-Notif transport. When this transport is used, four new leaves and a dtls container allow configuring UDP-Notif receiver parameters. The source address of the UDP-Notif message can be configured using the "source-address" leaf at the subscription level as defined in Section 2.5 of [RFC8639] or by setting the leaf "local-address" using the "ietf-udp-notif-transport" YANG module. When both are configured, the UDP-Notif message MUST use the address configured in the "local-address" leaf defined in the "ietf-udp-notif-transport" YANG module. The model defines the following YANG tree [RFC8340]: Huang-Feng, et al. Expires 30 January 2027 [Page 17] Internet-Draft UDP-Notif July 2026 module: ietf-udp-notif-transport augment /sn:subscriptions/snr:receiver-instances /snr:receiver-instance/snr:transport-type: +--:(udp-notif) +--rw udp-notif-receiver +--rw remote-address inet:host +--rw remote-port inet:port-number +--rw local-address? inet:ip-address | {local-binding}? +--rw local-port? inet:port-number | {local-binding}? +--rw dtls! {dtls}? | +--rw client-identity! | | +--rw (auth-type) | | +--:(certificate) {client-ident-x509-cert}? | | | ... | | +--:(raw-public-key) | | | {client-ident-raw-public-key}? | | | ... | | +--:(tls12-psk) {client-ident-tls12-psk}? | | | ... | | +--:(tls13-epsk) {client-ident-tls13-epsk}? | | ... | +--rw server-authentication | | +--rw ca-certs! {server-auth-x509-cert}? | | | +--rw (inline-or-truststore) | | | ... | | +--rw ee-certs! {server-auth-x509-cert}? | | | +--rw (inline-or-truststore) | | | ... | | +--rw raw-public-keys! {server-auth-raw-public-key}? | | | +--rw (inline-or-truststore) | | | ... | | +--rw tls12-psks? empty | | | {server-auth-tls12-psk}? | | +--rw tls13-epsks? empty | | {server-auth-tls13-epsk}? | +--rw hello-params {tlscmn:hello-params}? | +--rw tls-versions | | +--rw min? identityref | | +--rw max? identityref | +--rw cipher-suites | +--rw cipher-suite* | tlscsa:tls-cipher-suite-algorithm +--rw enable-segmentation? boolean +--rw max-segment-size? uint16 Huang-Feng, et al. Expires 30 January 2027 [Page 18] Internet-Draft UDP-Notif July 2026 7.2. YANG Module This YANG module is used to configure, on a publisher, a receiver willing to consume notification messages. This module augments the "ietf-subscribed-notif-receivers" module to define a UDP-Notif transport receiver. The grouping "udp-notif-receiver" defines the necessary parameters to configure the transport defined in this document using the generic "udp-client" grouping from the "ietf-udp- client" module [I-D.ietf-netconf-udp-client-server] and the "tls- client-grouping" defined in the "ietf-tls-client" module [RFC9645]. It uses data types defined in [RFC6991]. file "ietf-udp-notif-transport@2026-07-29.yang" module ietf-udp-notif-transport { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-udp-notif-transport"; prefix unt; import ietf-subscribed-notifications { prefix sn; reference "RFC 8639: Subscription to YANG Notifications"; } import ietf-subscribed-notif-receivers { prefix snr; reference "draft-ietf-netconf-https-notif: An HTTPS-based Transport for Configured Subscriptions"; } import ietf-udp-client { prefix udpc; reference "draft-ietf-netconf-udp-client-server: YANG Grouping for UDP Clients and UDP Servers"; } import ietf-tls-client { prefix tlsc; reference "RFC 9645: YANG Groupings for TLS Clients and TLS Servers"; } organization "IETF NETCONF (Network Configuration) Working Group"; contact "WG Web: WG List: Authors: Tianran Zhou Huang-Feng, et al. Expires 30 January 2027 [Page 19] Internet-Draft UDP-Notif July 2026 Thomas Graf Pierre Francois Alex Huang Feng Paolo Lucente "; description "Defines a model for configuring UDP-Notif as a transport for configured subscriptions [RFC8639]. Copyright (c) 2026 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 (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself for full legal notices. 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 (RFC 2119) (RFC 8174) when, and only when, they appear in all capitals, as shown here."; revision 2026-07-29 { description "Initial revision"; reference "RFC XXXX: UDP-based Transport for Configured Subscriptions"; } /* * FEATURES */ feature encode-cbor { description "Indicates that CBOR encoding of notification messages is supported."; Huang-Feng, et al. Expires 30 January 2027 [Page 20] Internet-Draft UDP-Notif July 2026 reference "RFC 9254: CBOR Encoding of Data Modeled with YANG"; } feature dtls { description "Indicates that DTLS encryption of UDP-Notif messages is supported. UDP-Notif mandates that, in unsecured networks, DTLS 1.2 or later MUST be supported, and DTLS 1.3 SHOULD be supported."; reference "RFC6347: Datagram Transport Layer Security Version 1.2, RFC 9147: The Datagram Transport Layer Security (DTLS) Protocol Version 1.3"; } /* * IDENTITIES */ identity udp-notif { base sn:transport; base sn:configurable-encoding; description "UDP-Notif is used as transport for notification messages and state change notifications."; } identity encode-cbor { base sn:encoding; description "Encode data using CBOR."; reference "RFC 9254: CBOR Encoding of Data Modeled with YANG"; } identity unsupported-max-segment-size { base sn:establish-subscription-error; base sn:modify-subscription-error; description "Error triggered when the specified value 'max-segment-size' is not supported by the publisher. An implementation may only support a subset of the uint16."; reference "RFC XXXX: UDP-based Transport for Configured Subscriptions"; } grouping udp-notif-receiver { Huang-Feng, et al. Expires 30 January 2027 [Page 21] Internet-Draft UDP-Notif July 2026 description "Provides a reusable identification of a UDP-Notif target receiver."; uses udpc:udp-client { refine "remote-port" { mandatory true; } } container dtls { if-feature "dtls"; presence "dtls"; uses tlsc:tls-client-grouping { // Remove keep-alives for DTLS refine "keepalives" { if-feature "not tlsc:tls-client-keepalives"; } } description "Container for configuring DTLS parameters."; } leaf enable-segmentation { type boolean; default "true"; description "When disabled, the publisher will not segment UDP-Notif messages. This may cause IP-layer fragmentation when messages are larger than the MTU. IP fragmentation is discouraged (RFC 8085, RFC 8900) and generally unsafe. Disabling is not recommended."; } leaf max-segment-size { type uint16; description "UDP-Notif provides a configurable max-segment-size to control the size of each segment (UDP-Notif header, with options, included). The publisher may trigger an 'unsupported-max-segment-size' error if the publisher does not support the configured value."; } } augment "/sn:subscriptions/snr:receiver-instances/" + "snr:receiver-instance/snr:transport-type" { case udp-notif { container udp-notif-receiver { description "The UDP-Notif receiver to send notifications to."; Huang-Feng, et al. Expires 30 January 2027 [Page 22] Internet-Draft UDP-Notif July 2026 uses udp-notif-receiver; } } description "Augments the transport-type choice to include the 'udp-notif' transport."; } } 8. IANA Considerations This document defines new registries under a new registry group entitled "UDP-Notif Protocol", and updates the IETF XML and YANG module registries. 8.1. UDP-Notif Protocol Registry Group This document requests IANA to create a new registry group called "UDP-Notif protocol". Under this registry group, three registries are to be created as described in the following sections. 8.1.1. UDP-Notif Media Types Registry All UDP-Notif messages contain a 4-bit media type identifier, for which IANA is to create and maintain a new registry entitled "UDP- Notif Media Types" under the registry group "UDP-Notif Protocol". This document defines the following media type values: +=======+=======================================+===========+ | Value | Description | Reference | +=======+=======================================+===========+ | 0 | Reserved | RFC-to-be | +-------+---------------------------------------+-----------+ | 1 | media type application/yang-data+json | RFC8040 | +-------+---------------------------------------+-----------+ | 2 | media type application/yang-data+xml | RFC8040 | +-------+---------------------------------------+-----------+ | 3 | media type application/yang-data+cbor | RFC9254 | +-------+---------------------------------------+-----------+ Table 1: Initial UDP-Notif Media Types Registry Future assignments are to be made using the Standards Action process defined in Section 4.9 of [RFC8126]. Assignments consist of the value, a short description of the media type and the document reference (e.g., RFC number). Huang-Feng, et al. Expires 30 January 2027 [Page 23] Internet-Draft UDP-Notif July 2026 8.1.2. UDP-Notif Option Types Registry UDP-Notif uses an 8-bit option type (see Section 4), for which IANA is to create and maintain a new registry entitled "UDP-Notif Option Types" under the registry group "UDP-Notif Protocol". This document defines the following option type values: +=======+=====================+===========+ | Value | Description | Reference | +=======+=====================+===========+ | 0 | Reserved | RFC-to-be | +-------+---------------------+-----------+ | 1 | Segmentation Option | RFC-to-be | +-------+---------------------+-----------+ Table 2: Initial UDP-Notif Option Types Registry Future assignments are to be made using the Standards Action process defined in Section 4.9 of [RFC8126]. Assignments consist of the value, a short description of the option and the document reference (e.g., RFC number). Specifications requesting allocation of a new UDP-Notif Option Type MUST define the option format and encoding, specify the processing rules for publishers and receivers, document any ordering, alignment, or padding requirements, and describe any constraints on the use of the option. 8.1.3. UDP-Notif Header Version Registry UDP-Notif header uses a 3-bit header version, for which IANA is to create and maintain a new registry entitled "UDP-Notif Header Version" under the registry group "UDP-Notif Protocol". This document defines the following header version values: Huang-Feng, et al. Expires 30 January 2027 [Page 24] Internet-Draft UDP-Notif July 2026 +=======+===============+=======================================+ | Value | Description | Reference | +=======+===============+=======================================+ | 0 | UDP based | draft-ietf-netconf-udp-pub-channel-05 | | | Publication | | | | Channel for | | | | Streaming | | | | Telemetry | | +-------+---------------+---------------------------------------+ | 1 | UDP-based | RFC-to-be | | | Transport for | | | | Configured | | | | Subscriptions | | +-------+---------------+---------------------------------------+ Table 3: Initial UDP-Notif Header Version Registry Note: There is an older specification of this transport protocol defined in [I-D.ietf-netconf-udp-pub-channel] that was deployed in some networks. To enable differentiating both protocols, different version numbers are used. The current specification replaces [I-D.ietf-netconf-udp-pub-channel] and uses 1 as its version, while the header defined in [I-D.ietf-netconf-udp-pub-channel] uses 0. Future assignments are to be made using the Standards Action process defined in Section 4.9 of [RFC8126]. Assignments consist of the value, a description of the header version and the document reference (e.g., RFC number). 8.2. URI IANA is also requested to register the following URI in the "ns" registry within the "IETF XML Registry" group [RFC3688]: URI: urn:ietf:params:xml:ns:yang:ietf-udp-notif-transport Registrant Contact: The IESG. XML: N/A; the requested URI is an XML namespace. 8.3. YANG Module Name IANA is requested to register the following YANG module in the "YANG Module Names" registry [RFC6020] within the "YANG Parameters" registry group. Huang-Feng, et al. Expires 30 January 2027 [Page 25] Internet-Draft UDP-Notif July 2026 Name: ietf-udp-notif-transport Maintained by IANA: N Namespace: urn:ietf:params:xml:ns:yang:ietf-udp-notif-transport Prefix: unt Reference: RFC-to-be 9. Implementation Status Note to the RFC-Editor: Please remove this section before publishing. 9.1. Open Source Publisher INSA Lyon implemented this document for a YANG Push publisher in an example implementation. The open source code can be obtained here: [INSA-Lyon-Publisher]. 9.2. Open Source Receiver Library INSA Lyon implemented this document for a YANG Push receiver as a library. The open source code can be obtained here: [INSA-Lyon-Receiver]. 9.3. Pmacct Data Collection The open source YANG push receiver library [INSA-Lyon-Receiver] has been integrated into the Pmacct open source Network Telemetry data collection [Paolo-Lucente-Pmacct]. 9.4. Huawei VRP Huawei implemented this document for a YANG Push publisher in their VRP platform. 9.5. 6WIND VSR 6WIND implemented this document for a YANG Push publisher in their VSR platform. 9.6. Cisco IOS XR Cisco implemented this document for a YANG Push publisher in their IOS XR platform. Huang-Feng, et al. Expires 30 January 2027 [Page 26] Internet-Draft UDP-Notif July 2026 10. Operational Considerations As described in Section 5, the loss of segments and notifications SHOULD be monitored for each Message Publisher ID and at the YANG- Push receiver to detect congestion and message loss in the network between the publisher and receiver. The Quality of Service (QoS) queues for CS2 (Class Selector 2) marked packets on the network interfaces between the publisher and receiver SHOULD be monitored to ensure that the configured traffic volume limits are not exceeded. 10.1. ICMP Error Handling Considerations UDP-Notif publishers operate over UDP and may receive ICMP error messages generated by the network. The handling of ICMP messages follows the recommendations specified in Section 5.2 of [RFC8085]. Implementations may record ICMP errors and make such information available to network management systems. In particular, ICMP errors indicating persistent delivery failures may provide useful information for diagnosing subscription or connectivity issues. Publishers SHOULD NOT attempt to infer application-level semantics from ICMP messages beyond the guidance provided in Section 5.2 of [RFC8085]. 11. Security Considerations As mentioned above, the proposed mechanism MUST be used only in controlled environments, as defined in Section 3.6 of [RFC8085], also known as "limited domains", as defined in [RFC8799]. In order to protect the UDP transport session from off-path attacks, unicast reverse path forwarding [RFC8704] SHOULD be configured at the edges of the network between the publisher and receiver to prevent an application from IP spoofing. Further, as described in Section 5.1 of [RFC8085], the source port of the UDP transport session SHOULD be randomized where [RFC6056] can be taken as guidance. Huang-Feng, et al. Expires 30 January 2027 [Page 27] Internet-Draft UDP-Notif July 2026 Section 6 of [RFC8085] states that "UDP applications that need to protect their communications against eavesdropping, tampering, or message forgery, SHOULD employ end-to-end security services provided by other IETF protocols". Even though a security layer within controlled environments is not necessarly required, for networks that are not secured, a secure transport providing confidentiality, integrity protection, authentication, and replay protection MUST be implemented. A specification of UDP-Notif using DTLS as its encryption layer is presented in Section 6. As implementation guidance, receivers SHOULD implement a mechanism to mitigate replay and reordering attacks on the UDP-Notif Message ID space associated with each Message Publisher ID. A sliding acceptance window is one possible mechanism to achieve this goal. With this approach, for each Message Publisher ID, the receiver maintains the highest Message ID observed and accepts a messages only if its Message ID falls within a configurable reordering window below that value and a configurable forward window above it. With a sliding acceptance window, notifications with Message IDs below the lower boundary are considered stale or replayed, while notifications beyond the forward boundary are considered invalid. Within the acceptance window, receivers SHOULD track the received (Message Publisher ID, Message ID) pairs to detect and discard duplicates. The lower boundary MAY be advanced as notifications are successfully delivered to the application, allowing older incomplete notifications below the boundary to be discarded without waiting for reassembly timeouts. Other mechanisms providing equivalent protection against replayed, duplicated, or excessively delayed UDP-Notif Messages MAY be used. The following text uses the template described in Section 3.7 of [I-D.ietf-netmod-rfc8407bis]. The "ietf-udp-notif-transport" YANG module defines a data model that is designed to be accessed via YANG-based management protocols, such as NETCONF [RFC6241] and RESTCONF [RFC8040]. These protocols have to use a secure transport layer (e.g., SSH [RFC6242], TLS [RFC8446], and QUIC [RFC9000]) and have to use mutual authentication. The Network Configuration Access Control Model (NACM) [RFC8341] provides the means to restrict access for particular NETCONF or RESTCONF users to a preconfigured subset of all available NETCONF or RESTCONF protocol operations and content. There are a number of data nodes defined in this YANG module that are writable/creatable/deletable (i.e., config true, which is the default). These data nodes may be considered sensitive or vulnerable in some network environments. Write operations (e.g., edit-config) Huang-Feng, et al. Expires 30 January 2027 [Page 28] Internet-Draft UDP-Notif July 2026 to these data nodes without proper protection can have a negative effect on network operations. These are the subtrees and data nodes and their sensitivity/vulnerability: * The data nodes "remote-address", "remote-port", "local-address", and "local-port" in the "ietf-udp-notif-transport" module specify transport parameters for the recipient of UDP-Notif messages. Unauthorized modification of these transport parameters could redirect notifications to unintended recipients. This YANG module uses groupings from other YANG modules that define nodes that may be considered sensitive or vulnerable in network environments. Refer to the Security Considerations of [I-D.ietf-netconf-udp-client-server] and [RFC9645] for information as to which nodes may be considered sensitive or vulnerable in network environments. 12. Contributors Guangying Zheng Huawei 101 Yu-Hua-Tai Software Road Nanjing Jiangsu, China Email: zhengguangying@huawei.com Yunan Gu Huawei Beijing China Email: guyunan@huawei.com 13. Acknowledgements The authors of this documents would like to thank Lucas Aubard, Alexander Clemm, Benoit Claise, Ebben Aries, Eric Voit, Huiyang Yang, Kent Watsen, Mahesh Jethanandani, Marco Tollini, Hannes Tschofenig, Michael Tuxen, Rob Wilton, Sean Turner, Stephane Frenot, Timothy Carey, Tim Jenkins, Tom Petch, Joseph Touch, Andy Bierman, Carsten Bormann, Mohamed Boucadair, Weiqiang Cheng, Giuseppe Fioccola, Camilo Cardona, Qiufang Ma, James Cumming, Qin Wu and Gorry Fairhurst for their constructive suggestions for improving this document. 14. References 14.1. Normative References Huang-Feng, et al. Expires 30 January 2027 [Page 29] Internet-Draft UDP-Notif July 2026 [I-D.ietf-netconf-distributed-notif] Zhou, T., Zheng, G., Voit, E., Graf, T., and P. Francois, "Subscription to Notifications in a Distributed Architecture", Work in Progress, Internet-Draft, draft- ietf-netconf-distributed-notif-19, 13 April 2026, . [I-D.ietf-netconf-https-notif] Jethanandani, M. and K. Watsen, "An HTTPS-based Transport for YANG Notifications", Work in Progress, Internet-Draft, draft-ietf-netconf-https-notif-16, 30 June 2026, . [I-D.ietf-netconf-udp-client-server] Feng, A. H., Francois, P., and K. Watsen, "YANG Groupings for UDP Clients and UDP Servers", Work in Progress, Internet-Draft, draft-ietf-netconf-udp-client-server-10, 16 December 2025, . [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, . [RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, DOI 10.17487/RFC5234, January 2008, . [RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010, . [RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347, January 2012, . [RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, July 2013, . Huang-Feng, et al. Expires 30 January 2027 [Page 30] Internet-Draft UDP-Notif July 2026 [RFC8085] Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage Guidelines", BCP 145, RFC 8085, DOI 10.17487/RFC8085, March 2017, . [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 8126, DOI 10.17487/RFC8126, June 2017, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, March 2018, . [RFC8342] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K., and R. Wilton, "Network Management Datastore Architecture (NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018, . [RFC8639] Voit, E., Clemm, A., Gonzalez Prieto, A., Nilsen-Nygaard, E., and A. Tripathy, "Subscription to YANG Notifications", RFC 8639, DOI 10.17487/RFC8639, September 2019, . [RFC8640] Voit, E., Clemm, A., Gonzalez Prieto, A., Nilsen-Nygaard, E., and A. Tripathy, "Dynamic Subscription to YANG Events and Datastores over NETCONF", RFC 8640, DOI 10.17487/RFC8640, September 2019, . [RFC8650] Voit, E., Rahman, R., Nilsen-Nygaard, E., Clemm, A., and A. Bierman, "Dynamic Subscription to YANG Events and Datastores over RESTCONF", RFC 8650, DOI 10.17487/RFC8650, November 2019, . [RFC9147] Rescorla, E., Tschofenig, H., and N. Modadugu, "The Datagram Transport Layer Security (DTLS) Protocol Version 1.3", RFC 9147, DOI 10.17487/RFC9147, April 2022, . Huang-Feng, et al. Expires 30 January 2027 [Page 31] Internet-Draft UDP-Notif July 2026 [RFC9254] Veillette, M., Ed., Petrov, I., Ed., Pelov, A., Bormann, C., and M. Richardson, "Encoding of Data Modeled with YANG in the Concise Binary Object Representation (CBOR)", RFC 9254, DOI 10.17487/RFC9254, July 2022, . [RFC9645] Watsen, K., "YANG Groupings for TLS Clients and TLS Servers", RFC 9645, DOI 10.17487/RFC9645, October 2024, . 14.2. Informative References [BCP195] Best Current Practice 195, . At the time of writing, this BCP comprises the following: Moriarty, K. and S. Farrell, "Deprecating TLS 1.0 and TLS 1.1", BCP 195, RFC 8996, DOI 10.17487/RFC8996, March 2021, . Sheffer, Y., Saint-Andre, P., and T. Fossati, "Recommendations for Secure Use of Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS)", BCP 195, RFC 9325, DOI 10.17487/RFC9325, November 2022, . [BCP230] Best Current Practice 230, . At the time of writing, this BCP comprises the following: Bonica, R., Baker, F., Huston, G., Hinden, R., Troan, O., and F. Gont, "IP Fragmentation Considered Fragile", BCP 230, RFC 8900, DOI 10.17487/RFC8900, September 2020, . [Errata-6211] Watsen, Kent., "Errata 6211", 2024, . [I-D.ietf-netconf-udp-pub-channel] Zheng, G., Zhou, T., and A. Clemm, "UDP based Publication Channel for Streaming Telemetry", Work in Progress, Internet-Draft, draft-ietf-netconf-udp-pub-channel-05, 11 March 2019, . Huang-Feng, et al. Expires 30 January 2027 [Page 32] Internet-Draft UDP-Notif July 2026 [I-D.ietf-netmod-rfc8407bis] Bierman, A., Boucadair, M., and Q. Wu, "Guidelines for Authors and Reviewers of Documents Containing YANG Data Models", Work in Progress, Internet-Draft, draft-ietf- netmod-rfc8407bis-28, 5 June 2025, . [INSA-Lyon-Publisher] "INSA Lyon, YANG Push publisher example implementation", . [INSA-Lyon-Receiver] "INSA Lyon, YANG Push receiver library implementation", . [Paolo-Lucente-Pmacct] "Paolo Lucente, Pmacct open source Network Telemetry Data Collection", . [RFC4594] Babiarz, J., Chan, K., and F. Baker, "Configuration Guidelines for DiffServ Service Classes", RFC 4594, DOI 10.17487/RFC4594, August 2006, . [RFC6056] Larsen, M. and F. Gont, "Recommendations for Transport- Protocol Port Randomization", BCP 156, RFC 6056, DOI 10.17487/RFC6056, January 2011, . [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., and A. Bierman, Ed., "Network Configuration Protocol (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011, . [RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011, . [RFC7011] Claise, B., Ed., Trammell, B., Ed., and P. Aitken, "Specification of the IP Flow Information Export (IPFIX) Protocol for the Exchange of Flow Information", STD 77, RFC 7011, DOI 10.17487/RFC7011, September 2013, . Huang-Feng, et al. Expires 30 January 2027 [Page 33] Internet-Draft UDP-Notif July 2026 [RFC7951] Lhotka, L., "JSON Encoding of Data Modeled with YANG", RFC 7951, DOI 10.17487/RFC7951, August 2016, . [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, . [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", STD 86, RFC 8200, DOI 10.17487/RFC8200, July 2017, . [RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018, . [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, . [RFC8641] Clemm, A. and E. Voit, "Subscription to YANG Notifications for Datastore Updates", RFC 8641, DOI 10.17487/RFC8641, September 2019, . [RFC8704] Sriram, K., Montgomery, D., and J. Haas, "Enhanced Feasible-Path Unicast Reverse Path Forwarding", BCP 84, RFC 8704, DOI 10.17487/RFC8704, February 2020, . [RFC8799] Carpenter, B. and B. Liu, "Limited Domains and Internet Protocols", RFC 8799, DOI 10.17487/RFC8799, July 2020, . [RFC9000] Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based Multiplexed and Secure Transport", RFC 9000, DOI 10.17487/RFC9000, May 2021, . Appendix A. UDP-Notif Examples This non-normative section shows two examples of how the the "ietf- udp-notif-transport" YANG module can be used to configure a [RFC8639] based publisher to send notifications to a receiver and an example of a YANG Push notification message using UDP-Notif transport protocol. Huang-Feng, et al. Expires 30 January 2027 [Page 34] Internet-Draft UDP-Notif July 2026 A.1. Configuration for UDP-Notif transport with DTLS disabled This example shows how UDP-Notif can be configured without DTLS encryption. It illustrates the definition of two receivers, one uses an IPv4 as its destination address and another uses IPv6. The IPv4 receiver is bound to the subscription. =============== NOTE: '\' line wrapping per RFC 8792 ================ 6666 ds:oper\ ational /if:int\ erfaces/interface unt:udp-notif encode-json subscription-specific-receiver ipv4-udp-notif-receiver active 6000 ipv4-udp-notif-receiver 192.0.2.1 12345 true 9000 Huang-Feng, et al. Expires 30 January 2027 [Page 35] Internet-Draft UDP-Notif July 2026 ipv6-udp-notif-receiver 2001:db8:abcd:12::1 12345 true 9000 A.2. Configuration for UDP-Notif transport with DTLS enabled This example shows how UDP-Notif can be configured with DTLS encryption. =============== NOTE: '\' line wrapping per RFC 8792 ================ 6666 ds:oper\ ational /if:int\ erfaces/interface unt:udp-notif encode-json subscription-specific-receiver-def udp-notif-receiver-dtls active 6000 Huang-Feng, et al. Expires 30 January 2027 [Page 36] Internet-Draft UDP-Notif July 2026 udp-notif-receiver-dtls 2001:db8:abcd:12::1 12345 ct:octet-string-key-format BASE64VALUE= example_external_id sha-256 example_context_string 8443 12345 Server Cert Issuer #1 BASE64VALUE= Server Cert Issuer #2 BASE64VALUE= My Application #1 BASE64VALUE= My Application #2 BASE64VALUE= Huang-Feng, et al. Expires 30 January 2027 [Page 37] Internet-Draft UDP-Notif July 2026 corp-fw1 ct:subject-public-key-info-format BASE64VALUE= corp-fw2 ct:subject-public-key-info-format BASE64VALUE= true 9000 A.3. YANG Push message with UDP-Notif transport protocol This example shows how UDP-Notif is used as a transport protocol to send a "push-update" notification [RFC8641] encoded in JSON [RFC7951]. Assuming the publisher needs to send the JSON payload showed in Figure 5, the UDP-Notif transport is encoded following the Figure 6. The UDP-Notif message is then encapsulated in a UDP datagram. Huang-Feng, et al. Expires 30 January 2027 [Page 38] Internet-Draft UDP-Notif July 2026 { "ietf-notification:notification": { "eventTime": "2024-02-10T08:00:11.22Z", "ietf-yang-push:push-update": { "id": 1011, "datastore-contents": { "ietf-interfaces:interfaces": [ { "interface": { "name": "eth0", "oper-status": "up" } } ] } } } } Figure 5: JSON Payload to be sent 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-----+-+-------+---------------+-------------------------------+ |Ver=1|0| MT=1 | Header_Len=12 | Message_Length=230 | +-----+-+-------+---------------+-------------------------------+ | Message Publisher ID=2 | +---------------------------------------------------------------+ | Message ID=1563 | +---------------------------------------------------------------+ | YANG Push JSON payload (Len=218 octets) | |{"ietf-notification:notification":{"eventTime":"2024-02-10T08:0| |0:11.22Z","ietf-yang-push:push-update":{"id":1011,"datastore-co| |ntents":{"ietf-interfaces:interfaces":[{"interface":{"name":"et| |h0","oper-status":"up"}}]}}}} | +---------------------------------------------------------------+ Figure 6: UDP-Notif transport message Authors' Addresses Alex Huang Feng Deutsche Telekom Barcelona Spain Email: alex.huang-feng@t-systems.com Huang-Feng, et al. Expires 30 January 2027 [Page 39] Internet-Draft UDP-Notif July 2026 Pierre Francois INSA-Lyon Lyon France Email: pierre.francois@insa-lyon.fr Tianran Zhou Huawei 156 Beiqing Rd., Haidian District Beijing China Email: zhoutianran@huawei.com Thomas Graf Swisscom Binzring 17 CH- Zuerich 8045 Switzerland Email: thomas.graf@swisscom.com Paolo Lucente NTT Siriusdreef 70-72 Hoofddorp, WT 2132 Netherlands Email: paolo@ntt.net Huang-Feng, et al. Expires 30 January 2027 [Page 40]