module ietf-tcp-common {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-tcp-common";
  prefix tcpcmn;

  organization
    "IETF NETCONF (Network Configuration) Working Group and the
     IETF TCP Maintenance and Minor Extensions (TCPM) Working Group";

  contact
    "WG Web:   https://datatracker.ietf.org/wg/netconf
               https://datatracker.ietf.org/wg/tcpm
     WG List:  NETCONF WG list <mailto:netconf@ietf.org>
               TCPM WG list <mailto:tcpm@ietf.org>
     Authors:  Kent Watsen <mailto:kent+ietf@watsen.net>
               Michael Scharf
               <mailto:michael.scharf@hs-esslingen.de>";

  description
    "This module define a reusable 'grouping' that is common
     to both TCP clients and TCP servers.  This grouping statement
     is used by both the 'ietf-tcp-client' and 'ietf-tcp-server'
     modules.

     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.

     Copyright (c) 2024 IETF Trust and the persons identified
     as authors of the code.  All rights reserved.

     Redistribution and use in source and binary forms, with
     or without modification, is permitted pursuant to, and
     subject to the license terms contained in, the Revised
     BSD License set forth in Section 4.c of the IETF Trust's
     Legal Provisions Relating to IETF Documents
     (https://trustee.ietf.org/license-info).

     This version of this YANG module is part of RFC 9643
     (https://www.rfc-editor.org/info/rfc9643); see the RFC
     itself for full legal notices.";

  revision 2024-10-10 {
    description
      "Initial version.";
    reference
      "RFC 9643: YANG Groupings for TCP Clients and TCP Servers";
  }

  // Features

  feature keepalives-supported {
    description
      "Indicates that keepalives are supported.";
  }

  // Groupings

  grouping tcp-common-grouping {
    description
      "A reusable grouping for configuring TCP parameters common
       to TCP connections as well as the operating system as a
       whole.";
    container keepalives {
      if-feature "keepalives-supported";
      presence "Indicates that keepalives are enabled, aligning to
                the requirement in Section 3.8.4 of RFC 9293 that
                states keepalives are off by default.";
      description
        "Configures the keepalive policy to proactively test the
         aliveness of the TCP peer.  An unresponsive TCP peer is
         dropped after approximately (idle-time + max-probes *
         probe-interval) seconds.  Further guidance can be found
         in Section 2.1.5 of RFC 9643.";
      reference
        "RFC 9293: Transmission Control Protocol (TCP)";
      leaf idle-time {
        type uint16 {
          range "1..max";
        }
        units "seconds";
        default "7200";
        description
          "Sets the amount of time after which a TCP-level probe
           message will be sent to test the aliveness of the TCP
           peer if no data has been received from the TCP peer.
           Two hours (7200 seconds) is a safe value, per Section
           3.8.4 of RFC 9293.";
        reference
          "RFC 9293: Transmission Control Protocol (TCP)";
      }
      leaf max-probes {
        type uint16 {
          range "1..max";
        }
        default "9";
        description
          "Sets the maximum number of sequential keepalive probes
           that can fail to obtain a response from the TCP peer
           before assuming the TCP peer is no longer alive.";
      }
      leaf probe-interval {
        type uint16 {
          range "1..max";
        }
        units "seconds";
        default "75";
        description
          "Sets the time interval between failed probes.  The
           interval SHOULD be significantly longer than one second
           in order to avoid harm on a congested link.";
      }
    } // container keepalives
  } // grouping tcp-common-grouping

}