[email protected]

module ietf-if-extensions {
  yang-version 1.1;

  namespace "urn:ietf:params:xml:ns:yang:ietf-if-extensions";

  prefix if-ext;

  import ietf-yang-types {
    prefix yang;
    reference "RFC 6991: Common YANG Data Types";
  }

  import ietf-interfaces {
    prefix if;
    reference
      "RFC 8343: A YANG Data Model For Interface Management";
  }

  import iana-if-type {
    prefix ianaift;
    reference "RFC 7224: IANA Interface Type YANG Module";
  }

  organization
    "IETF NETMOD (NETCONF Data Modeling Language) Working Group";

  contact
    "WG Web:   <http://tools.ietf.org/wg/netmod/>
     WG List:  <mailto:netmod@ietf.org>

     Editor:   Robert Wilton
               <mailto:rwilton@cisco.com>";

  description
    "This module contains common definitions for extending the IETF
     interface YANG model (RFC 8343) with common configurable layer 2
     properties.

     Copyright (c) 2023 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 2023-01-26 {
    description
      "Initial revision.";

    reference
      "RFC XXXX, Common Interface Extension YANG Data Models";
  }

  feature link-flap-suppression {
    description
      "This feature indicates that configurable interface link
       delay is supported, which is a feature is used to limit the
       propagation of very short interface link state flaps.";
    reference "RFC XXXX, Section 2.1 Link Flap Suppression";
  }

  feature dampening {
    description
      "This feature indicates that the device supports interface
       dampening, which is a feature that is used to limit the
       propagation of interface link state flaps over longer
       periods.";
    reference "RFC XXXX, Section 2.2 Dampening";
  }

  feature loopback {
    description
      "This feature indicates that configurable interface loopback is
       supported.";
    reference "RFC XXXX, Section 2.4 Loopback";
  }

  feature max-frame-size {
    description
      "This feature indicates that the device supports configuring or
       reporting the maximum frame size on interfaces.";
    reference "RFC XXXX, Section 2.5 Maximum Frame Size";
  }

  feature sub-interfaces {
    description
      "This feature indicates that the device supports the
       instantiation of sub-interfaces.  Sub-interfaces are defined
       as logical child interfaces that allow features and forwarding
       decisions to be applied to a subset of the traffic processed
       on the specified parent interface.";
    reference "RFC XXXX, Section 2.6 Sub-interface";
  }

  /*
   * Define common identities to help allow interface types to be
   * assigned properties.
   */
  identity sub-interface {
    description
      "Base type for generic sub-interfaces.

       New or custom interface types can derive from this type to
       inherit generic sub-interface configuration.";
    reference "RFC XXXX, Section 2.6 Sub-interface";
  }

  identity ethSubInterface{
    base ianaift:l2vlan;
    base sub-interface;

    description
      "This identity represents the child sub-interface of any
       interface types that uses Ethernet framing (with or without
       802.1Q tagging).";
  }

  identity loopback {
    description "Base identity for interface loopback options";
    reference "RFC XXXX, Section 2.4";
  }
  identity internal {
    base loopback;
    description
      "All egress traffic on the interface is internally looped back
       within the interface to be received on the ingress path.";
    reference "RFC XXXX, Section 2.4";
  }
  identity line {
    base loopback;
    description
      "All ingress traffic received on the interface is internally
       looped back within the interface to the egress path.";
    reference "RFC XXXX, Section 2.4";
  }
  identity connector {
    base loopback;
    description
      "The interface has a physical loopback connector attached that
       loops all egress traffic back into the interface's ingress
       path, with equivalent semantics to loopback internal.";
    reference "RFC XXXX, Section 2.4";
  }


  identity forwarding-mode {
    description "Base identity for forwarding-mode options.";
    reference "RFC XXXX, Section 2.7";
  }
  identity physical {
    base forwarding-mode;
    description
      "Physical layer forwarding.  This includes DWDM or OTN based
       optical switching.";
    reference "RFC XXXX, Section 2.7";
  }
  identity data-link {
    base forwarding-mode;
    description
      "Layer 2 based forwarding, such as Ethernet/VLAN based
       switching, or L2VPN services.";
    reference "RFC XXXX, Section 2.7";
  }
  identity network {
    base forwarding-mode;
    description
      "Network layer based forwarding, such as IP, MPLS, or L3VPNs.";
    reference "RFC XXXX, Section 2.7";
  }


  /*
   * Augments the IETF interfaces model with leaves to configure
   * and monitor link-flap-suppression on an interface.
   */
  augment "/if:interfaces/if:interface" {
    description
      "Augments the IETF interface model with optional common
       interface level commands that are not formally covered by any
       specific standard.";

    /*
     * Defines standard YANG for the Link Flap Suppression feature.
     */
    container link-flap-suppression {
      if-feature "link-flap-suppression";
      description
        "Holds link flap related feature configuration.";
      leaf down {
        type uint32;
        units milliseconds;
        description
          "Delays the propagation of a 'loss of carrier signal' event
           that would cause the interface state to go down, i.e. the
           command allows short link flaps to be suppressed. The
           configured value indicates the minimum time interval (in
           milliseconds) that the link signal must be continuously
           down before the interface state is brought down. If not
           configured, the behavior on loss of link signal is
           vendor/interface specific, but with the general
           expectation that there should be little or no delay.";
      }
      leaf up {
        type uint32;
        units milliseconds;
        description
          "Defines the minimum time interval (in milliseconds) that
           the link signal must be continuously present and error
           free before the interface state is allowed to transition
           from down to up.  If not configured, the behavior is
           vendor/interface specific, but with the general
           expectation that sufficient default delay should be used
           to ensure that the interface is stable when enabled before
           being reported as being up.  Configured values that are
           too low for the hardware capabilties may be rejected.";
      }
      leaf carrier-transitions {
        type yang:counter64;
        units transitions;
        config false;
        description
          "Defines the number of times the underlying link state
           has changed to, or from, state up.  This counter should be
           incremented even if the high layer interface state changes
           are being suppressed by a running link flap suppression
           timer.";
      }
      leaf timer-running {
        type enumeration {
          enum none {
            description
              "No link flap suppression timer is running.";
          }
          enum up {
            description
              "link-flap-suppression up timer is running.  The
               underlying link state is up, but interface state is
               not reported as up.";
          }
          enum down {
            description
              "link-flap-suppression down timer is running.
               Interface state is reported as up, but the underlying
               link state is actually down.";
          }
        }
        config false;
        description
          "Reports whether a link flap suppression timer is actively
           running, in which case the interface state does not match
           the underlying link state.";
      }

      reference "RFC XXXX, Section 2.1 Link Flap Suppression";
    }

    /*
     * Augments the IETF interfaces model with a container to hold
     * generic interface dampening
     */
    container dampening {
      if-feature "dampening";
      presence
        "Enable interface link flap dampening with default settings
         (that are vendor/device specific).";
      description
        "Interface dampening limits the propagation of interface link
         state flaps over longer periods.";
      reference "RFC XXXX, Section 2.2 Dampening";

      leaf half-life {
        type uint32;
        units seconds;
        description
          "The time (in seconds) after which a penalty would be half
           its original value.  Once the interface has been assigned
           a penalty, the penalty is decreased at a decay rate
           equivalent to the half-life.  For some devices, the
           allowed values may be restricted to particular multiples
           of seconds.  The default value is vendor/device
           specific.";
        reference "RFC XXXX, Section 2.3.2 Half-Life Period";
      }

      leaf reuse {
        type uint32;
        description
          "Penalty value below which a stable interface is
           unsuppressed (i.e. brought up) (no units).  The default
           value is vendor/device specific.  The penalty value for a
           link up->down state change is 1000 units.";
        reference "RFC XXXX, Section 2.2.3 Reuse Threshold";
      }

      leaf suppress {
        type uint32;
        description
          "Limit at which an interface is suppressed (i.e. held down)
           when its penalty exceeds that limit (no units).  The value
           must be greater than the reuse threshold.  The default
           value is vendor/device specific.  The penalty value for a
           link up->down state change is 1000 units.";
        reference "RFC XXXX, Section 2.2.1 Suppress Threshold";
      }

      leaf max-suppress-time {
        type uint32;
        units seconds;
        description
          "Maximum time (in seconds) that an interface can be
           suppressed before being unsuppressed if no further link
           up->down state change penalties have been applied.  This
           value effectively acts as a ceiling that the penalty value
           cannot exceed.  The default value is vendor/device
           specific.";
        reference "RFC XXXX, Section 2.2.4 Maximum Suppress Time";
      }

      leaf penalty {
        type uint32;
        config false;
        description
          "The current penalty value for this interface.  When the
           penalty value exceeds the 'suppress' leaf then the
           interface is suppressed (i.e. held down).";
        reference "RFC XXXX, Section 2.2 Dampening";
      }

      leaf suppressed {
        type boolean;
        config false;
        description
          "Represents whether the interface is suppressed (i.e. held
           down) because the 'penalty' leaf value exceeds the
           'suppress' leaf.";
        reference "RFC XXXX, Section 2.2 Dampening";
      }

      leaf time-remaining {
        when '../suppressed = "true"' {
          description
            "Only suppressed interfaces have a time remaining.";
        }
        type uint32;
        units seconds;
        config false;
        description
          "For a suppressed interface, this leaf represents how long
           (in seconds) that the interface will remain suppressed
           before it is allowed to go back up again.";
        reference "RFC XXXX, Section 2.2 Dampening";
      }
    }

    /*
     * Various types of interfaces support a configurable layer 2
     * encapsulation, any that are supported by YANG should be
     * listed here.
     *
     * Different encapsulations can hook into the common encaps-type
     * choice statement.
     */
    container encapsulation {
      when
        "derived-from-or-self(../if:type,
                              'ianaift:ethernetCsmacd') or
         derived-from-or-self(../if:type,
                              'ianaift:ieee8023adLag') or
         derived-from-or-self(../if:type, 'ianaift:pos') or
         derived-from-or-self(../if:type,
                              'ianaift:atmSubInterface') or
         derived-from-or-self(../if:type, 'ianaift:l2vlan') or
         derived-from-or-self(../if:type, 'ethSubInterface')" {

        description
          "All interface types that can have a configurable L2
           encapsulation.";
      }

      description
        "Holds the OSI layer 2 encapsulation associated with an
         interface.";
      choice encaps-type {
        description
          "Extensible choice of layer 2 encapsulations";
        reference "RFC XXXX, Section 2.3 Encapsulation";
      }
    }

     /*
      * Various types of interfaces support loopback configuration,
      * any that are supported by YANG should be listed here.
      */
    leaf loopback {
      when "derived-from-or-self(../if:type,
                                 'ianaift:ethernetCsmacd') or
            derived-from-or-self(../if:type, 'ianaift:sonet') or
            derived-from-or-self(../if:type, 'ianaift:atm') or
            derived-from-or-self(../if:type, 'ianaift:otnOtu')" {
        description
          "All interface types that support loopback configuration.";
      }
      if-feature "loopback";
      type identityref {
        base loopback;
      }
      description "Enables traffic loopback.";
      reference "RFC XXXX, Section 2.4 Loopback";
    }

    /*
     * Allows the maximum frame size to be configured or reported.
     */
    leaf max-frame-size {
      if-feature "max-frame-size";
      type uint32 {
        range "64 .. max";
      }
      description
        "The maximum size of layer 2 frames that may be transmitted
         or received on the interface (including any frame header,
         maximum frame payload size, and frame checksum sequence).

         If configured, the max-frame-size also limits the maximum
         frame size of any child sub-interfaces.  The MTU available
         to higher layer protocols is restricted to the maximum frame
         payload size, and MAY be further restricted by explicit
         layer 3 or protocol specific MTU configuration.";

      reference "RFC XXXX, Section 2.5 Maximum Frame Size";
    }

    /*
     * Augments the IETF interfaces model with a leaf that indicates
     * which mode, or layer, is being used to forward the traffic.
     */
    leaf forwarding-mode {
      type identityref {
        base forwarding-mode;
      }
      config false;

      description
        "The forwarding mode that the interface is operating in.";
      reference "RFC XXXX, Section 2.7 Forwarding Mode";
    }
  }

  /*
   * Add generic support for sub-interfaces.
   *
   * This should be extended to cover all interface types that are
   * child interfaces of other interfaces.
   */
  augment "/if:interfaces/if:interface" {
    when "derived-from(if:type, 'sub-interface') or
          derived-from-or-self(if:type, 'ianaift:l2vlan') or
          derived-from-or-self(if:type, 'ianaift:atmSubInterface') or
          derived-from-or-self(if:type, 'ianaift:frameRelay')"  {
      description
        "Any ianaift:types that explicitly represent sub-interfaces
         or any types that derive from the sub-interface identity.";
    }
    if-feature "sub-interfaces";

    description
      "Adds a parent interface field to interfaces that model
       sub-interfaces.";
    leaf parent-interface {

      type if:interface-ref;

      mandatory true;
      description
        "This is the reference to the parent interface of this
         sub-interface.";
      reference "RFC XXXX, Section 2.6 Sub-interface";
    }
  }

  /*
   * Add discard counter for unknown sub-interface encapsulation
   */
  augment "/if:interfaces/if:interface/if:statistics" {
    when "derived-from-or-self(../if:type,
                               'ianaift:ethernetCsmacd') or
          derived-from-or-self(../if:type,
                               'ianaift:ieee8023adLag') or
          derived-from-or-self(../if:type, 'ianaift:ifPwType')" {
      description
        "Applies to interfaces that can demultiplex ingress frames to
         sub-interfaces.";
    }
    if-feature "sub-interfaces";

    description
      "Augment the interface model statistics with a sub-interface
       demux discard counter.";
    leaf in-discard-unknown-encaps {
      type yang:counter64;
      units frames;
      description
        "A count of the number of frames that were well formed, but
         otherwise discarded because their encapsulation does not
         classify the frame to the interface or any child
         sub-interface.  E.g., a frame might be discarded because the
         it has an unknown VLAN Id, or does not have a VLAN Id when
         one is expected.

         For consistency, frames counted against this counter are
         also counted against the IETF interfaces statistics.  In
         particular, they are included in in-octets and in-discards,
         but are not included in in-unicast-pkts, in-multicast-pkts
         or in-broadcast-pkts, because they are not delivered to a
         higher layer.

         Discontinuities in the values of this counter can occur at
         re-initialization of the management system, and at other
         times as indicated by the value of the 'discontinuity-time'
         leaf defined in the ietf-interfaces YANG module
         (RFC 8343).";
    }
  }
}