Skip to main content

Per-Entry Soft-State Refresh Horizon and Paced Fragmentation Scheduling for Fast Network Notification (FANN) Telemetry
draft-li-fann-soft-state-refresh-yang-00

Document Type Active Internet-Draft (individual)
Authors Zhiqiang Li , Zongpeng Du , Junjie Wang , Wei Cheng , Ying Zhao , Chunhao Zhao , Xun Sun
Last updated 2026-11-02
RFC stream (None)
Intended RFC status (None)
Formats
Yang Validation 0 errors, 0 warnings
Stream Stream state (No stream defined)
Consensus boilerplate Unknown
RFC Editor Note (None)
IESG IESG state I-D Exists
Telechat date (None)
Responsible AD (None)
Send notices to (None)
draft-li-fann-soft-state-refresh-yang-00
Fast Network Notifications                                         Z. Li
Internet-Draft                                                     Z. Du
Intended status: Standards Track                            China Mobile
Expires: 3 May 2027                                              J. Wang
                                                                W. Cheng
                                                                 Y. Zhao
                                                                  Centec
                                                                 C. Zhao
                                                                    SAIA
                                                                  X. Sun
                                                                   Inesa
                                                         30 October 2026

Per-Entry Soft-State Refresh Horizon and Paced Fragmentation Scheduling
             for Fast Network Notification (FANN) Telemetry
                draft-li-fann-soft-state-refresh-yang-00

Abstract

   This document specifies a Standards Track per-entry soft-state
   refresh horizon profile, a bounded multi-packet fragmentation
   scheduling invariant, and a YANG 1.1 data model (ietf-fann-soft-
   state-refresh) for Fast Network Notification (FANN) link-quality
   telemetry.  To prevent unrefreshed link entries from persisting
   indefinitely when partial event-triggered updates share a transport
   channel with periodic full sweeps, each receiver maintains an
   independent monotonic receipt horizon per six-tuple link-record key.
   Furthermore, when a full periodic sweep spans F fragmented datagrams
   paced at inter-packet interval T_spacing, the refresh period
   T_refresh and expiration horizon T_expire satisfy T_refresh <=
   T_expire - M - (F - 1) * T_spacing.MUST NOT reset the full-sweep
   periodic timer for omitted records.  The refresh bound explicitly
   accounts for multi-packet fragmentation emission duration (T_refresh
   <= T_expire - M - (F - 1) * T_spacing).

Discussion and Scope

   This is an individual Standards Track proposal prepared for review.
   It has not been adopted by a working group, and no independent
   implementation or interoperability result is claimed.  The proposed
   scope and sponsoring venue require community discussion.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

Li, et al.                 Expires 3 May 2027                   [Page 1]
Internet-Draft       FANN Soft-State Refresh Horizon        October 2026

   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 3 May 2027.

Copyright Notice

   Copyright (c) 2026 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   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
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
     1.2.  Scope of the Guarantee  . . . . . . . . . . . . . . . . .   3
   2.  Record Identity and Local State . . . . . . . . . . . . . . .   4
   3.  Configuration and Deployment Agreement  . . . . . . . . . . .   4
   4.  Sender Procedure  . . . . . . . . . . . . . . . . . . . . . .   5
   5.  Receiver Procedure  . . . . . . . . . . . . . . . . . . . . .   6
   6.  Router-Info Carriage  . . . . . . . . . . . . . . . . . . . .   8
   7.  Worked Trace and Interoperability Cases . . . . . . . . . . .   8
   8.  YANG Data Model Augmentation for FANN Per-Record Aging  . . .   9
   9.  Security and Operational Considerations . . . . . . . . . . .  11
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  12
   11. Implementation Status and Integration Plan  . . . . . . . . .  12
   12. Normative References  . . . . . . . . . . . . . . . . . . . .  13
   13. Informative References  . . . . . . . . . . . . . . . . . . .  13
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  14

Li, et al.                 Expires 3 May 2027                   [Page 2]
Internet-Draft       FANN Soft-State Refresh Horizon        October 2026

1.  Introduction

   Link-quality advertisements can contain several records and can be
   split across packets.  A receiver that refreshes every record when
   any packet from a helper arrives can retain an omitted record
   indefinitely.  This document specifies a per-record receipt-aging
   profile for the Link Quality Telemetry model [LQ-INFO] and its UDP
   binding [LQ-UDP].  It also specifies that partial triggered
   advertisements must not postpone the sender's periodic coverage of
   other records.

   The profile is a focused proposed amendment to those individual
   drafts.  It does not define a new notification packet, metric,
   transport, congestion-control algorithm, or forwarding policy.
   [ROUTER-INFO] already discusses per-neighbor and per-link refresh and
   aging.  The contribution here is to make the aging unit, sender
   scheduling, and composition with nested LQ records explicit.  The
   preferred progression is joint integration into the base documents,
   not parallel standardization of the same mechanism.

   The failure scenario follows from partial refresh and loss semantics;
   it is not presented as a measured production incident.  The FANN
   problem statement [FANN-PROBLEM] establishes the wider notification
   problem, but does not constitute working-group adoption of this
   particular profile.  The current framework [FANN-FRAMEWORK] remains
   work in progress.

1.1.  Requirements Language

   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.

1.2.  Scope of the Guarantee

   The normative bound is the maximum local time for which a record can
   influence a consumer without another accepted update explicitly
   carrying that record.  It is a bound on receipt recency.  It is not a
   bound on the age of the underlying physical measurement, on network
   delivery delay, or on successful recovery after loss.  UDP can lose
   an unbounded number of successive advertisements.

Li, et al.                 Expires 3 May 2027                   [Page 3]
Internet-Draft       FANN Soft-State Refresh Horizon        October 2026

   No timestamp synchronization or sender boot epoch is added to the
   wire format.  Deployments requiring a bound on measurement age or
   cryptographic freshness need additional mechanisms in the underlying
   binding.  A delayed but accepted packet can renew receipt recency
   while containing an old observation; this profile MUST NOT be
   advertised as preventing that case.

2.  Record Identity and Local State

   For the native LQ model the receiver keys a record by the tuple
   (administrative receive scope, sender AS qualifier, sender node ID,
   remote AS qualifier, remote node ID, link ID).  Zero AS qualifiers
   retain the unqualified semantics of [LQ-INFO]; the administrative
   receive scope MUST keep otherwise ambiguous identifiers separate.
   Interface indices or node IDs from unrelated scopes MUST NOT alias
   the same state entry.

   Each admitted record stores its value, monotonic accepted-receipt
   time, expiry deadline, and validity state.  Validity is absent,
   fresh, or stale.  Stale means that this profile no longer permits use
   of the retained quality observation.  It does not by itself mean that
   the physical link is down, healthy, or has zero capacity.

   Sender heartbeat state and per-record validity are separate.  An
   accepted packet for record B can establish that the sender is
   responsive while record A expires.  A heartbeat failure can
   invalidate all records from that sender according to the base
   mechanism, but heartbeat success MUST NOT refresh an omitted record.
   Topology validity remains an independent condition.

3.  Configuration and Deployment Agreement

   The operator configures an upper bound R on the interval between
   completed emissions that explicitly refresh each advertised record.
   R is expressed in integer milliseconds and MUST be positive.  The
   receiver uses a positive integer miss multiplier M and computes L = M
   * R using checked arithmetic.  L is the local receipt lifetime.  An
   implementation MUST reject a configuration whose product is not
   representable in its timer system or whose scheduling precision
   cannot enforce it.

   R is a per-record coverage budget, not necessarily the nominal packet
   timer.  If the periodic scheduler has a maximum gap of ceil(1.1 * T)
   and a full emission cycle takes at most E milliseconds, a
   conservative choice is R = ceil(1.1 * T) + E.  E includes
   serialization, batching, and scheduler delays for the entire
   advertised record set.  An implementation MUST NOT set E to zero
   merely because each individual packet is small.

Li, et al.                 Expires 3 May 2027                   [Page 4]
Internet-Draft       FANN Soft-State Refresh Horizon        October 2026

   The sender and receiver MUST be provisioned consistently for this
   profile.  There is no in-band negotiation in this version.  Enabling
   only the receiver provides conservative expiry but does not ensure
   that the sender refreshes records frequently enough; enabling only
   the sender does not correct receiver aging.  A mixed deployment
   requires explicit operational compatibility assessment.  The packet
   format is unchanged, but the profile intentionally changes behavior
   relative to the timer-reset rule in [LQ-INFO] and [LQ-UDP].

   When L is reduced, existing deadlines MUST be shortened to no later
   than accepted-receipt-time + new-L.  Increasing L MUST NOT extend an
   existing record's deadline; the longer value applies after a new
   accepted explicit update.  Changes of administrative scope, sender
   identity mapping, or topology mapping MUST invalidate affected
   entries until valid updates are admitted under the new mapping.

4.  Sender Procedure

   While a record is advertised as current, the sender MUST schedule
   explicit refreshes so that the interval between completed emissions
   for that record does not exceed R under the declared operating
   envelope.  Periodic coverage includes unchanged records.  Triggered
   advertisements can contain a subset, but MUST NOT reset or postpone
   the periodic coverage deadlines of omitted records.

   Splitting a full refresh across packets does not make the packet
   group atomic.  The sender follows the base binding's sequence-number
   rules and advances the packet sequence as required.  Every packet
   contains self-contained records.  The sender MUST budget for the
   entire group when claiming R and MUST account for the maximum record
   count and link serialization rate.

   The sender MUST NOT present a stale local measurement as newly
   sampled merely by periodically transmitting it.  Existing
   measurement-validity procedures remain applicable.  This profile does
   not add an observation-age field, so a receiver cannot derive such
   age solely from successful refreshes.  If local sampling is
   unavailable, the sender MUST stop refreshing the affected
   observation, or use an unavailable indication only if the selected
   base binding explicitly defines one.  It MUST NOT manufacture a
   healthy score.  Stopping refresh permits the receiver's deadline to
   expire; it does not signal an immediate physical link failure.

Li, et al.                 Expires 3 May 2027                   [Page 5]
Internet-Draft       FANN Soft-State Refresh Horizon        October 2026

   If overload prevents compliance with R, the sender SHOULD expose a
   local alarm and reduce the advertised set or renegotiate
   configuration through management.  It MUST NOT silently advertise
   that the guarantee still holds.  The receiver still expires entries
   according to L; thus overload can reduce usable telemetry without
   extending stale use.

   When a link-quality record first becomes eligible for periodic
   advertisement, its first completed explicit emission MUST occur no
   later than R after that eligibility event under the declared
   operating envelope.  Initial coverage and subsequent periodic sweeps
   share the same per-record refresh bound.  An event-triggered emission
   satisfies the refreshed record's own deadline but MUST NOT postpone
   the emission deadline of any omitted link record.

5.  Receiver Procedure

   The receiver MUST validate packet framing, source and scope checks,
   configured security protections, and the base sequence rule before
   any timer renewal.  A rejected, duplicate, or stale packet renews
   neither a record timer nor a sender heartbeat in this profile.
   Serial comparisons use the bit width and procedures of the base
   binding and [RFC1982]; the exactly-half-range case is not a newer
   value.

   This profile retains the base per-sender packet ordering.  For
   example, if packet 102 containing B arrives before packet 101
   containing A, the base rule can reject packet 101.  The receiver MUST
   NOT treat receipt of B as recovery of A.  A subsequently accepted
   explicit refresh can restore A.  This profile does not change to per-
   record serial numbers or claim to repair all reordering losses.

   For an otherwise admissible packet, the receiver validates every
   record and rejects the packet if it contains duplicate composite keys
   or structurally invalid records.  No timer is partially updated
   before this validation completes.  Optional fields continue to follow
   the base binding's rules.  An unsupported record type MUST NOT be
   interpreted as a refresh of a previously known type.

   For every valid, admitted record K explicitly present, the receiver
   applies the following operation.  The time is the local monotonic
   time at successful admission, not an untrusted sender timestamp.

Li, et al.                 Expires 3 May 2027                   [Page 6]
Internet-Draft       FANN Soft-State Refresh Horizon        October 2026

   on_admit(K, value, now):
       state[K].value = value
       state[K].last = now
       state[K].deadline = checked_add(now, L)
       state[K].validity = fresh

   usable(K, now):
       return (state[K].validity == fresh
               and now < state[K].deadline
               and topology_allows(K)
               and parent_carriage_allows(K))

   At now equal to the deadline, the record is not usable.  Periodic
   cleanup may run later, but the forwarding consumer MUST test the
   deadline or an equivalent hardware validity mechanism before using
   the observation.  A timer implementation with bounded error must
   conservatively account for that error; delayed housekeeping MUST NOT
   create extra usable lifetime.

   Entries absent from the packet are unchanged.  Their deadlines MUST
   NOT be extended.  Expiry marks an entry stale and prevents its
   quality value from affecting forwarding.  The consumer then uses its
   configured base-protocol fallback, such as topology-only forwarding,
   withdrawing the affected optimization, or another independently
   validated source.  This document does not mandate a new fallback that
   contradicts the base protocol's eligibility rule.

   Receiver restart or loss of validity state makes all affected
   observations unusable until renewed.  Reset of a sender's sequence
   state follows the base binding's recovery rule and its security
   limitations.  A heartbeat timeout is not proof of a fresh
   authenticated incarnation.  Deployments that cannot exclude delayed
   or replayed traffic across that reset MUST NOT claim measurement
   freshness from this profile.  Adding a boot epoch would require a
   separate wire-format agreement.

   Any installed path weight or derived forwarding state that depends on
   a link-quality record MUST NOT remain eligible for traffic steering
   beyond the earliest applicable input record expiry, topology
   invalidation, or enclosing node-record expiry.  An implementation
   MUST either propagate that conservative expiration timestamp into the
   derived forwarding table entry or atomically invalidate the derived
   entry at the exact expiry boundary, even if background telemetry
   table garbage collection has not yet executed.

Li, et al.                 Expires 3 May 2027                   [Page 7]
Internet-Draft       FANN Soft-State Refresh Horizon        October 2026

6.  Router-Info Carriage

   When LQ records are carried inside Router-Info, the validity checks
   compose.  A record is usable only while its own LQ deadline, the
   applicable enclosing Router-Info record lifetime, and topology
   conditions all permit it.  Expiry of the enclosing information
   invalidates its dependent observations.  Receipt of an unrelated
   Router-Info TLV, a different neighbor, or another nested link record
   MUST NOT extend an LQ record's lifetime.

   The base Router-Info refresh-rate rules remain applicable to their
   own record types, including the treatment of one-time notifications.
   This profile MUST NOT create an indefinite lifetime for periodic LQ
   records by selecting a zero refresh value.  A deployment with no
   finite agreed LQ coverage bound cannot enable this profile for those
   records.

   Because [ROUTER-INFO] already has per-record aging, the normative
   work needed there may be only a clarification of composition with the
   nested LQ TLV.  A new parallel timer or packet type is not required
   when existing implementation state can express the same deadlines.

7.  Worked Trace and Interoperability Cases

   Assume T = 20 ms, maximum jittered gap 22 ms, E = 1 ms, R = 23 ms,
   and M = 3.  Then L = 69 ms.  At t = 0, A and B are admitted.  Updates
   containing only B are admitted at t = 20 and t = 40.  At t = 69, A is
   unusable even though the sender heartbeat remains healthy.  B's
   deadline is t = 109.  A is usable again only after an explicit
   accepted update, for example at t = 75, establishing a new deadline
   at t = 144.

   This trace is an arithmetic example, not a measured hardware result.
   Loss of every packet carrying A can keep A stale indefinitely.  A
   full sender refresh schedule creates transmission opportunities; it
   cannot promise successful delivery in R milliseconds.

   An interoperability suite MUST cover omitted records, duplicate
   packets, duplicate keys, packet reordering, exact deadline
   boundaries, sequence wrap and half-range ambiguity, sender restart,
   changed scope, reduced and increased lifetime configuration, nested
   outer expiry, receiver resource exhaustion, and sustained loss.
   Expected outcomes should be compared at the usability interface, not
   only by inspecting whether entries remain allocated.

Li, et al.                 Expires 3 May 2027                   [Page 8]
Internet-Draft       FANN Soft-State Refresh Horizon        October 2026

   Interoperability verification MUST additionally test the initial-
   emission deadline bound R and verify that derived forwarding weights
   cease influencing packet selection at the exact nanosecond a
   constituent link record expires, prior to asynchronous background
   record purge.

8.  YANG Data Model Augmentation for FANN Per-Record Aging

   To ensure interoperable configuration and operational monitoring of
   the per-record receipt-aging profile across Fast Network Notification
   (FANN) senders and receivers, this section defines the YANG 1.1
   [RFC7950] module ietf-fann-soft-state-refresh, which augments the
   Link Quality Telemetry model [LQ-INFO], uses the common data types of
   [RFC9911], and conforms to NMDA [RFC8342] and the YANG module
   guidance in [RFC9907].

   <CODE BEGINS> file "ietf-fann-soft-state-refresh@2026-10-30.yang"
   module ietf-fann-soft-state-refresh {
     yang-version 1.1;
     namespace
       "urn:ietf:params:xml:ns:yang:ietf-fann-soft-state-refresh";
     prefix fann-ssr;

     import ietf-yang-types {
       prefix yang;
       reference
         "RFC 9911: Common YANG Data Types";
     }

     organization
       "IETF Fast Network Notifications (FANN) Working Group";
     contact
       "WG Web:   <https://datatracker.ietf.org/wg/fann/>
        WG List:  <mailto:fann@ietf.org>
        Author:   Zhiqiang Li
                  <mailto:lizhiqiangyjy@chinamobile.com>";
     description
       "This module defines configuration and operational state
        parameters for per-record receipt aging and bounded refresh
        scheduling in Fast Network Notification (FANN) Link-Quality
        Telemetry.

        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

Li, et al.                 Expires 3 May 2027                   [Page 9]
Internet-Draft       FANN Soft-State Refresh Horizon        October 2026

        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 2026-10-30 {
       description
         "Initial version specifying per-record receipt aging
          parameters including multi-packet fragmentation emission
          margin (E).";
       reference
         "RFC XXXX: Per-Record Receipt Aging and Bounded Refresh
          Scheduling for Fast Network Notification (FANN)
          Link-Quality Telemetry";
     }

     container fann-soft-state-refresh {
       description
         "Per-record receipt aging configuration and operational
          telemetry.";
       leaf record-expire-ms {
         type uint32 {
           range "1..3600000";
         }
         units "milliseconds";
         default "1000";
         description
           "Receiver per-record expiration interval (T_expire).";
       }
       leaf safety-margin-ms {
         type uint32;
         units "milliseconds";
         default "200";
         description
           "Configured transit, jitter, and loss safety margin (M).";
       }
       leaf fragment-spacing-ms {
         type uint32;
         units "milliseconds";
         default "10";
         description
           "Maximum inter-fragment emission spacing (T_spacing).";
       }
       leaf max-fragments-per-sweep {
         type uint16 {
           range "1..1024";

Li, et al.                 Expires 3 May 2027                  [Page 10]
Internet-Draft       FANN Soft-State Refresh Horizon        October 2026

         }
         default "1";
         description
           "Maximum fragments (F) required to emit a full link-record
            sweep.";
       }
       leaf refresh-interval-ms {
         type uint32 {
           range "1..3600000";
         }
         units "milliseconds";
         must ". + ../safety-margin-ms + "
            + "((../max-fragments-per-sweep - 1) * "
            + "../fragment-spacing-ms) <= ../record-expire-ms" {
           error-message
             "T_refresh + M + (F - 1) * T_spacing MUST NOT exceed "
           + "T_expire.";
         }
         default "500";
         description
           "Bounded full-sweep refresh interval (T_refresh).";
       }
       leaf expired-record-purges {
         type yang:counter64;
         config false;
         description
           "Total number of link-quality records transitioned to
            Expired because T_now - T_rx_last >= T_expire.";
       }
     }
   }
   <CODE ENDS>

9.  Security and Operational Considerations

   Per-record deadlines prevent unrelated accepted traffic from
   extending a record's local receipt lifetime.  They do not
   authenticate telemetry.  Source-address checks and a hop-limit check
   restrict scope but are not cryptographic authentication.  The
   deployment MUST apply the base binding's security requirements and
   assess whether its link protection and operational trust suffice for
   the proposed use.

Li, et al.                 Expires 3 May 2027                  [Page 11]
Internet-Draft       FANN Soft-State Refresh Horizon        October 2026

   An on-link attacker able to inject accepted packets can create
   misleading records or advance serial state.  Per-record aging does
   not solve that attack.  Integrity protection, authorization of sender
   identities and scope, and protection against replay are required
   where that threat is in scope.  This document adds no authentication
   field and MUST NOT claim to provide such protection by itself.

   Receivers MUST bound admitted senders and records.  A record that
   cannot be stored MUST NOT be represented as fresh.  Resource eviction
   invalidates the affected observation; it MUST NOT transfer its
   deadline to another key.  Operators SHOULD monitor per-record expiry,
   heartbeat failure, sequence rejection, capacity rejection, and
   coverage-budget violations separately.

   Frequent expiry can cause forwarding changes, so implementations need
   a stable fallback and appropriate policy damping.  Any adaptation
   must respect the data transport's ordering assumptions; this profile
   does not authorize arbitrary packet spraying for RoCE traffic.
   Hardware timer capacity and update rate must be measured under the
   maximum advertised record set.

10.  IANA Considerations

   This document requests no IANA allocation.  It changes no codepoint,
   YANG namespace, packet header, or registry.  Its intended progression
   is integration of the specified behavior into the relevant base
   documents, subject to their editors and the FANN working group.  It
   does not claim to update an existing RFC.

11.  Implementation Status and Integration Plan

   No conforming hardware implementation or independent interoperability
   result is claimed.  The FANN charter [FANN-CHARTER] includes
   hardware-forwarding and interoperability requirements before protocol
   publication.  Model-level trace checks cannot satisfy those
   requirements.

   The proposed integration points are the per-entry last-seen and
   heartbeat procedures in Sections 6.2 and 6.5 of [LQ-INFO], its
   transmission procedure in Section 7.2, and the triggered/periodic
   interaction in Section 4.5 of [LQ-UDP].  Router-Info composition
   should be reviewed with its per-neighbor/link aging text and the LQ
   carriage rules.  The exact section numbers are tied to the cited -00
   revisions.

   Before adoption, the base editors should confirm whether current
   senders can omit unchanged records, whether complete periodic
   coverage is already intended, how reset and replay are handled, and

Li, et al.                 Expires 3 May 2027                  [Page 12]
Internet-Draft       FANN Soft-State Refresh Horizon        October 2026

   whether the receiver's existing per-entry timestamp is already used
   for expiry.  If an updated base draft specifies equivalent behavior,
   this proposal should be merged or retired instead of remaining a
   duplicate document.

12.  Normative References

   [RFC1982]  Elz, R. and R. Bush, "Serial Number Arithmetic", RFC 1982,
              DOI 10.17487/RFC1982, August 1996,
              <https://www.rfc-editor.org/info/rfc1982>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC7950]  Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
              RFC 7950, DOI 10.17487/RFC7950, August 2016,
              <https://www.rfc-editor.org/info/rfc7950>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [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,
              <https://www.rfc-editor.org/info/rfc8342>.

   [RFC9911]  Schönwälder, J., Ed., "Common YANG Data Types", RFC 9911,
              DOI 10.17487/RFC9911, December 2025,
              <https://www.rfc-editor.org/info/rfc9911>.

13.  Informative References

   [FANN-CHARTER]
              IETF, "Fast Network Notifications Working Group Charter",
              Snapshot accessed 28 October 2026; not an implementation
              of this proposal, October 2026,
              <https://datatracker.ietf.org/wg/fann/about/>.

   [FANN-FRAMEWORK]
              Song, H., Dong, J., Ali, Z., Cheng, W., Zhu, Y., Pang, R.,
              Contreras, L. M., and L. Guo, "A Framework for Fast
              Network Notifications", Work in Progress, Internet-Draft,
              draft-song-fann-framework-03, 26 October 2026,
              <https://datatracker.ietf.org/doc/html/draft-song-fann-
              framework-03>.

Li, et al.                 Expires 3 May 2027                  [Page 13]
Internet-Draft       FANN Soft-State Refresh Horizon        October 2026

   [FANN-PROBLEM]
              Dong, J., McBride, M., Clad, F., Zhang, Z. J., Zhu, Y.,
              Xu, X., Zhuang, R., Pang, R., Lu, H., Liu, Y., Contreras,
              L. M., Mehmet, D., and R. Rahman, "Fast Network
              Notifications Problem Statement", Work in Progress,
              Internet-Draft, draft-ietf-fann-problem-statement-01, 26
              October 2026, <https://datatracker.ietf.org/doc/html/
              draft-ietf-fann-problem-statement-01>.

   [LQ-INFO]  Pasalapudi, S. P. K. and V. P. Beeram, "A YANG Data Model
              for Link Quality Telemetry in CLOS Data Center Fabrics",
              Work in Progress, Internet-Draft, draft-praveen-fann-lq-
              telemetry-info-00, 21 July 2026,
              <https://datatracker.ietf.org/doc/html/draft-praveen-fann-
              lq-telemetry-info-00>.

   [LQ-UDP]   Pasalapudi, S. P. K. and V. P. Beeram, "A UDP Transport
              Binding for Link Quality Telemetry in CLOS Data Center
              Fabrics", Work in Progress, Internet-Draft, draft-praveen-
              fann-lq-telemetry-udp-00, 21 July 2026,
              <https://datatracker.ietf.org/doc/html/draft-praveen-fann-
              lq-telemetry-udp-00>.

   [RFC9907]  Bierman, A., Boucadair, M., Ed., and Q. Wu, "Guidelines
              for Authors and Reviewers of Documents Containing YANG
              Data Models", BCP 216, RFC 9907, DOI 10.17487/RFC9907,
              March 2026, <https://www.rfc-editor.org/info/rfc9907>.

   [ROUTER-INFO]
              Zhang, Z. J., Wang, K., Lin, C., Vaidya, N., Tantsura, J.,
              and Y. Liu, "Advertising Router Information", Work in
              Progress, Internet-Draft, draft-zzhang-fann-router-info-
              00, 6 July 2026, <https://datatracker.ietf.org/doc/html/
              draft-zzhang-fann-router-info-00>.

Authors' Addresses

   Zhiqiang Li
   China Mobile
   Beijing
   China
   Email: lizhiqiangyjy@chinamobile.com

   Zongpeng Du
   China Mobile
   Beijing
   China

Li, et al.                 Expires 3 May 2027                  [Page 14]
Internet-Draft       FANN Soft-State Refresh Horizon        October 2026

   Email: duzongpeng@chinamobile.com

   Junjie Wang
   Centec
   Shanghai
   China
   Email: wangjj@centec.com

   Wei Cheng
   Centec
   Shanghai
   China
   Email: chengw@centec.com

   Ying Zhao
   Centec
   Shanghai
   China
   Email: zhaoying@centec.com

   Chunhao Zhao
   SAIA
   Shanghai
   China
   Email: chunhao.zhao@sh-aia.com

   Xun Sun
   Inesa
   Shanghai
   China
   Email: sunxun@inesa.com

Li, et al.                 Expires 3 May 2027                  [Page 15]