module openconfig-transport-line-protection {

  yang-version "1";

  // namespace
  namespace "http://openconfig.net/yang/optical-transport-line-protection";

  prefix "oc-line-protect";

  import openconfig-extensions { prefix oc-ext; }
  import openconfig-types { prefix oc-types; }
  import openconfig-platform { prefix oc-platform; }

  // meta
  organization "OpenConfig working group";

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

  description
    "This model describes configuration and operational state data
    for optical line protection elements, deployed as part of a
    transport line system. An Automatic Protection Switch (APS)
    is typically installed in the same device as the amplifiers
    and wave-router, however an APS can also be a standalone
    device. In both scenarios, it serves the same purpose of
    providing protection using two dark fiber pairs to ensure the
    amplifiers can still receive a signal if one of the two fiber
    pairs is broken. The APS port details and directionality are
    shown below. The three major attributes, together with their
    modifiers, define the behavior of the APS and can be prioritized
    in the descending order as shown in the following table";

  //
  // Automatic Protection Switch (APS) port details and directionality.
  //                 _________
  //                 |       |
  //                 |       | <=== LINE-PRIMARY-IN
  //                 |       |
  // COMMON-IN  ===> |       | ===> LINE-PRIMARY-OUT
  //                 |       |
  //                 |  APS  |
  // COMMON-OUT <=== |       |
  //                 |       | <=== LINE-SECONDARY-IN
  //                 |       |
  //                 |       | ===> LINE-SECONDARY-OUT
  //                 |_______|
  //
  //
  // The interaction of configuration attributes that control the
  // protection switching behavior
  // +------------------+--------------------+------------------------+
  // | Attribute        | Modifier           | Behavior               |
  // +------------------+--------------------+------------------------+
  // | force-to-port    | n/a                | turns off switching    |
  // |                  |                    | by forcing to primary  |
  // |                  |                    | or secondary           |
  // +------------------+--------------------+------------------------+
  // | relative-switch  | relative-threshold | if set, overrides      |
  // | -threshold       | -offset            | primary and secondary  |
  // |                  |                    | switch thresholds      |
  // +------------------+--------------------+------------------------+
  // | primary-switch   | primary-switch     | sets respective        |
  // | -threshold,      | -hysteresis        | threshold to switch    |
  // | secondary-switch |                    | to opposite port       |
  // | -threshold       |                    |                        |
  // +------------------+--------------------+------------------------+

  oc-ext:openconfig-version "0.4.0";

  revision "2018-07-25" {
    description
      "Added wait-to-restore-time, hold-off-time,
      relative-switch-threshold, relative-switch-threshold-offset,
      forced-to-port, removed secondary-switch-hysteresis, and
      edited the description of primary-switch-threshold,
      secondary-switch-threshold, and primary-switch-hysteresis";
    reference "0.4.0";
  }

  revision "2017-09-08" {
    description
      "Correct bug with OSC interfaces";
    reference "0.3.1";
  }

  revision "2017-07-08" {
    description
      "Support multiple OCMs, add monitor port type
      and refs to hw ports, ";
    reference "0.3.0";
  }

  revision "2017-03-28" {
    description
      "Added min/max/avg stats, status for media channels, OCM, APS";
    reference "0.2.0";
  }

  revision "2016-08-05" {
    description
      "Initial public release";
    reference "0.1.0";
  }

  // extension statements

  // feature statements

  // identity statements

  identity APS_PATHS {
    description
      "Base identity for identifying the line paths on an
      automatic protection switch";
  }

  identity PRIMARY {
    base APS_PATHS;
    description
      "The primary line path connected to an automatic protection
      switch port indicating the primary/preferred path";
  }

  identity SECONDARY {
    base APS_PATHS;
    description
      "The secondary line path connected to an automatic protection
      switch port indicating the secondary path";
  }

  // grouping statements

  grouping aps-input-port-config {
    description
      "Grouping for config related to unidirectional automatic
      protection switch input ports";

    leaf enabled {
      type boolean;
      default "true";
      description
        "This leaf contains the configured, desired state of the
        port. Disabling the port turns off alarm reporting for
        the port";
    }

    leaf target-attenuation {
      type decimal64 {
        fraction-digits 2;
      }
      units dB;
      description
        "Target attenuation of the variable optical attenuator
        associated with the port in increments of 0.01 dB.";
    }
  }

  grouping aps-output-port-config {
    description
      "Grouping for config related to unidirectional automatic
      protection switch output ports";

    leaf target-attenuation {
      type decimal64 {
        fraction-digits 2;
      }
      units dB;
      description
        "Target attenuation of the variable optical attenuator
        associated with the port in increments of 0.01 dB";
    }
  }

  grouping aps-input-port-state {
    description
      "Grouping for state related to unidirectional automatic
      protection switch input ports";

    leaf attenuation {
      type decimal64 {
        fraction-digits 2;
      }
      units dB;
      description
        "The attenuation of the variable optical attenuator
        associated with the port in increments of 0.01 dB.";
    }

    container optical-power {
      description
        "The optical input power of this port in units of
        0.01dBm. Optical input power represents the signal
        traversing from an external destination into the module.
        The power is measured before any attenuation. If avg/min/max
        statistics are not supported, the target is expected to
        just supply the instant value";

      uses oc-types:avg-min-max-instant-stats-precision2-dBm;
    }
  }

  grouping aps-output-port-state {
    description
      "Grouping for state related to unidirectional automatic
      protection switch output ports";

    leaf attenuation {
      type decimal64 {
        fraction-digits 2;
      }
      units dB;
      description
        "The attenuation of the variable optical attenuator
        associated with the port in increments of 0.01 dB";
    }

    container optical-power {
      description
        "The optical output power of this port in units of
        0.01dBm. Optical output power represents the signal
        traversing from the module to an external destination. The
        power is measured after any attenuation. If avg/min/max
        statistics are not supported, the target is expected to
        just supply the instant value";

      uses oc-types:avg-min-max-instant-stats-precision2-dBm;
    }
  }

  grouping aps-ports {
    description
      "Top level grouping for automatic protection switch ports";

    container line-primary-in {
      description
        "Container for information related to the line primary
        input port";

      container config {
        description
          "Configuration data for the line primary input port";

        uses aps-input-port-config;
      }

      container state {

        config false;

        description
          "State data for the line primary input port";

        uses aps-input-port-config;
        uses aps-input-port-state;
      }

    }

    container line-primary-out {
      description
        "Container for information related to the line primary
        output port";

      container config {
        description
          "Configuration data for the line primary output port";

        uses aps-output-port-config;
      }

      container state {

        config false;

        description
          "State data for the line primary output port";

        uses aps-output-port-config;
        uses aps-output-port-state;
      }
    }

    container line-secondary-in {
      description
        "Container for information related to the line secondary
        input port";

      container config {
        description
          "Configuration data for the line secondary input port";

        uses aps-input-port-config;
      }

      container state {

        config false;

        description
          "State data for the line secondary input port";

        uses aps-input-port-config;
        uses aps-input-port-state;
      }
    }

    container line-secondary-out {
      description
        "Container for information related to the line secondary
        output port";

      container config {
        description
          "Configuration data for the line secondary output port";

        uses aps-output-port-config;
      }

      container state {

        config false;

        description
          "State data for the line secondary output port";

        uses aps-output-port-config;
        uses aps-output-port-state;
      }
    }

    container common-in {
      description
        "Container for information related to the line common
        input port";

      container config {
        description
          "Configuration data for the line common input port";

        uses aps-input-port-config;
      }

      container state {

        config false;

        description
          "State data for the line common input port";

        uses aps-input-port-config;
        uses aps-input-port-state;
      }
    }

    container common-output {
      description
        "Container for information related to the line common
        output port";

      container config {
        description
          "Configuration data for the line common output port";

        uses aps-output-port-config;
      }

      container state {

        config false;

        description
          "State data for the line common output port";

        uses aps-output-port-config;
        uses aps-output-port-state;
      }
    }
  }

  grouping aps-config {
    description
      "Configuration data for automatic protection switch modules";

    leaf name {
      type leafref {
        path "/oc-platform:components/oc-platform:component/" +
          "oc-platform:name";
      }
      description
        "Reference to the component name (in the platform model)
        corresponding to this automatic protection switch module
        in the device";
    }

    leaf revertive {
      type boolean;
      description
        "Revertive behavior of the module. If True, then
        automatically revert after protection switch once the
        fault is restored. This leaf is not valid when the
        relative-switch-threshold is in effect";
    }

    leaf wait-to-restore-time {
      type uint32;
      units milliseconds;
      description
         "The time that must elapse before an APS path
         that has recovered from an signal failure (SF) or signal
         degradation (SD) condition can be used again to transport
         the normal traffic signal. During this time period, an SF or
         SD condition shall override the wait-to-restore time period.
         This leaf can only take effect when the revertive leaf
         equals true";
    }

    leaf hold-off-time {
      type uint32;
      units milliseconds;
      description
        "The time delay between the declaration of an SF or SD
        condition and the initiation of the protection switching
        algorithm";
    }

    leaf primary-switch-threshold {
      type decimal64 {
        fraction-digits 2;
      }
      units dBm;
      description
        "The threshold at which the primary line port will switch to
        the opposite line port in increments of 0.01 dBm. If the
        hardware supports only one switch threshold for primary and
        and secondary ports then it is recommended to set both
        primary-switch-threshold and secondary-switch-threshold to
        the same value to be explicit. When the relative switch
        threshold is enabled, i.e. set to a non-zero value, the
        primary switch threshold will be overridden";
    }

    leaf primary-switch-hysteresis {
      type decimal64 {
        fraction-digits 2;
      }
      units dB;
      default 0;
      description
        "The delta in dB between the primary-switch-threshold
        and the signal received on the primary APS_PATH before
        initiating a switch from the secondary APS_PATH to the
        primary APS_PATH, in order to prevent toggling between ports
        when an input signal is very close to the threshold. A zero
        value means the switch hysteresis is disabled.";
    }

    leaf secondary-switch-threshold {
      type decimal64 {
        fraction-digits 2;
      }
      units dBm;
      description
        "The threshold at which the secondary line port will switch to
        the opposite line port in increments of 0.01 dBm. If the
        hardware supports only one switch threshold for primary and
        and secondary ports then it is recommended to set both
        primary-switch-threshold and secondary-switch-threshold to
        the same value to be explicit. When the relative switch
        threshold is enabled, i.e. set to a non-zero value, the
        secondary switch threshold will be overridden";
    }

    leaf relative-switch-threshold {
      type decimal64 {
        fraction-digits 2;
      }
      units dB;
      default 0;
      description
        "The delta threshold in dB at which the current line port
        will switch to the opposite line port. It can be set to
        the value of 0dB. When set to 0dB, the threshold is ignored
        and the system automatically applies the primary and
        secondary switch thresholds. When set to a non-zero value,
        it overrides the primary and secondary switch thresholds";
    }

    leaf relative-switch-threshold-offset {
      type decimal64 {
        fraction-digits 2;
      }
      units dB;
      default 0;
      description
        "The offset of the relative switch threshold that compensates
        the normal difference of receiving power between the primary
        and secondary line ports. A negative offset corresponds to
        the situation where the secondary line port receives a higher
        power than the primary line port in normal condition, and a
        positive offset means the opposite. The offset will only work
        when the relative switch threshold is set to a non-zero
        value";
    }

    leaf force-to-port {
      type enumeration {
        enum NONE {
          description
            "Do not force the switch to stay on any line port";
        }
        enum PRIMARY {
          description
            "Force the switch to stay on the primary line port";
        }
        enum SECONDARY {
          description
            "Force the switch to stay on the secondary line port";
        }
      }
      default NONE;
      description
        "Explicitly set the switch to stay on a port regardless of
        its operational condition";
    }
  }

  grouping aps-state {
    description
      "State data for automatic protection switch modules";

    leaf active-path {
      type identityref {
        base APS_PATHS;
      }
      description
        "Indicates which line path on the protection switch is
         currently the active path connected to the common port";
    }
  }

  grouping automatic-protection-switch-top {
    description
      "Top level grouping for automatic protection switch data";

    container aps-modules {
      description
        "Enclosing container for list of automatic protection
	       switch modules";

      list aps-module {
        key "name";
        description
          "List of automatic protection switch modules present
          in the device";

        leaf name {
          type leafref {
            path "../config/name";
          }
          description
            "Reference to the config name list key";
        }

        container config {
          description
            "Configuration data for an automatic protection
            switch module";

          uses aps-config;
        }

        container state {

          config false;

          description
            "Operational state data for an automatic protection
            switch module";

          uses aps-config;
          uses aps-state;
        }

        container ports {
          description
            "Top level grouping for automatic protection switch ports";

          uses aps-ports;
        }
      }
    }
  }

  grouping transport-line-protection-top {
    description
      "Top level grouping for transport line protection data";

    container aps {
      description
        "Top level grouping for automatic protection switch data";

      uses automatic-protection-switch-top;
    }
  }

  // data definition statements

  uses transport-line-protection-top;

}