module openconfig-bfd {

    yang-version 1;

    namespace
      "http://openconfig.net/yang/bfd";

    prefix oc-bfd;

    import openconfig-extensions {
      prefix oc-ext;
    }
    import openconfig-types {
      prefix oc-types;
    }
    import openconfig-interfaces {
      prefix oc-if;
    }
    import openconfig-inet-types {
      prefix oc-inet;
    }
    import openconfig-policy-types {
      prefix oc-pol-types;
    }
    import ietf-inet-types {
      prefix ietf-if;
    }

    organization "OpenConfig working group";

    contact
      "OpenConfig working group
www.openconfig.net";

    description
      "An OpenConfig model of Bi-Directional Forwarding Detection (BFD)
configuration and operational state.";

    revision "2025-03-18" {
      description
        "Clarify BFD session failure as a transition
from the UP state to the DOWN state. This does not include
UP to ADMIN_DOWN transitions, since when the BFD session is
administratively disabled it is not a session failure.";
      reference
        "0.4.1";

    }

    revision "2025-02-05" {
      description
        "Move the up-transitions leaf from the async and echo
sub-containers into the state container.";
      reference
        "0.4.0";

    }

    revision "2024-12-16" {
      description
        "Add Bfd diagnostic code for when
neighbor signaled session down. Specified in RFC5880.";
      reference
        "0.3.1";

    }

    revision "2024-03-05" {
      description
        "Add configuration of min interval, multiplier when
BFD is enabled at protocol level";
      reference
        "0.3.0";

    }

    revision "2023-08-09" {
      description
        "Update interface key to use interface-id type";
      reference
        "0.2.6";

    }

    revision "2023-02-06" {
      description
        "Clarify interface references.";
      reference
        "0.2.5";

    }

    revision "2022-06-28" {
      description
        "Remove reference to invalid oc-ift type check";
      reference
        "0.2.4";

    }

    revision "2021-06-16" {
      description
        "Remove trailing whitespace";
      reference
        "0.2.3";

    }

    revision "2021-03-17" {
      description
        "Remove augments from bfd module.
Add bfd support directly on the protocols";
      reference
        "0.2.2";

    }

    revision "2020-05-08" {
      description
        "Ensure that when statements reference only read-write leaves
from read-write contexts.
Add ietf-inet-types LAG type to conditions for micro-bfd.";
      reference
        "0.2.1";

    }

    revision "2019-10-25" {
      description "Correct when statements.";
      reference
        "0.2.0";

    }

    revision "2019-06-02" {
      description
        "Fix detection multiplier to be 8-bit value";
      reference
        "0.1.1";

    }

    revision "2018-11-21" {
      description
        "Add OpenConfig module metadata extensions.";
      reference
        "0.1.0";

    }

    revision "2017-10-19" {
      description
        "Adopt OpenConfig types models, type corrections";
      reference
        "0.0.2";

    }

    revision "2016-06-24" {
      description "Initial revision";
      reference
        "0.0.1";

    }

    oc-ext:openconfig-version "0.4.1";
    oc-ext:regexp-posix;
    oc-ext:catalog-organization "openconfig";
    oc-ext:origin "openconfig";

    typedef bfd-session-state {
      type enumeration {
        enum "UP" {
          value 0;
          description
            "The BFD session is perceived to be up by the system.";
        }
        enum "DOWN" {
          value 1;
          description
            "The BFD session is perceived to be down by the system.";
        }
        enum "ADMIN_DOWN" {
          value 2;
          description
            "The BFD session is administratively disabled.";
        }
        enum "INIT" {
          value 3;
          description
            "The BFD session is perceived to be initialising by the
system.";
        }
      }
      description
        "The state of the BFD session according to the system referred
to by the context of the leaf.";
      reference
        "RFC5880 - Bidirectional Forwarding Detection, Section
        4.1";

    }

    typedef bfd-diagnostic-code {
      type enumeration {
        enum "NO_DIAGNOSTIC" {
          value 0;
          description
            "No diagnostic code was specified, or the session has not
changed state.";
        }
        enum "DETECTION_TIMEOUT" {
          value 1;
          description
            "The control detection time expired: no BFD packet was
received within the required period.";
        }
        enum "ECHO_FAILED" {
          value 2;
          description
            "The BFD echo function failed - echo packets have not been
received for the required period of time.";
        }
        enum "FORWARDING_RESET" {
          value 3;
          description
            "The forwarding plane in the local system was reset - such
that the remote system cannot rely on the forwarding state of
the device specifying this error code.";
        }
        enum "PATH_DOWN" {
          value 4;
          description
            "Signalling outside of BFD specified that the path underlying
this session has failed.";
        }
        enum "CONCATENATED_PATH_DOWN" {
          value 5;
          description
            "When a BFD session runs over a series of path segments, this
error code indicates that a subsequent path segment (i.e.,
one in the transmit path between the source and destination
of the session) has failed.";
        }
        enum "ADMIN_DOWN" {
          value 6;
          description
            "The BFD session has been administratively disabled by the
peer.";
        }
        enum
          "REVERSE_CONCATENATED_PATH_DOWN" {
          value 7;
          description
            "In the case that a BFD session is running over a series of
path segments, this error code indicates that a path segment
on the reverse path (i.e., in the transmit direction from the
destination to the source of the session) has failed.";
        }
        enum "NEIGHBOR_DOWN" {
          value 8;
          description
            "The Bfd neighbor signaled session down - Bfd packet was received with
neighbor state down.";
        }
      }
      description
        "Diagnostic codes defined by BFD. These typically indicate the
reason for a change of session state. The NEIGHBOR_DOWN diagnostic
was added to the enum at value 8 to avoid making a breaking change.
This deviates from RFC5880 where the enum is value 3. This also
shifts the following values by 1, in relation to RFC5880:
FORWARDING_RESET, PATH_DOWN, CONCATENATED_PATH_DOWN,
ADMIN_DOWN, REVERSE_CONCATENATED_PATH_DOWN.";
      reference
        "RFC5880 - Bidirectional Forwarding Detection, Section
        4.1";

    }
  }  // module openconfig-bfd