etsi-nfv-vnf.yang 76.9 KB
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            enum "docker" {
              description
                "A docker container format.";
            }
            enum "ova" {
              description
                "An OVF package in a tarfile.";
            }
            enum "ovf" {
              description
                "The OVF container format.";
            }
          }
          description
            "The container format describes the container file
             format in which software image is provided.";
          reference
            "GS NFV IFA011: Section 7.1.6.5 SwImageDesc
             information element.";
        }
        leaf disk-format {
          mandatory true;
          type enumeration {
            enum "aki" {
              description
                "An Amazon kernel image.";
            }
            enum "ami" {
              description
                "An Amazon machine image.";
            }
            enum "ari" {
              description
                "An Amazon ramdisk image.";
            }
            enum "iso" {
              description
                "An archive format for the data contents of an
                 disk, such as CD-ROM.";
            }
            enum "qcow2" {
              description
                "Supported by the QEMU emulator that can expand
                 dynamically and supports Copy on Write.";
            }
            enum "raw" {
              description
                "An unstructured disk image format; if you have a
                 file without an extension it is possibly a raw
                 format.";
            }
            enum "vdi" {
              description
                "Supported by VirtualBox virtual machine monitor
                 and the QEMU emulator.";
            }
            enum "vhd" {
              description
                "The VHD disk format, a common disk format used by
                 virtual machine monitors from VMware, Xen,
                 Microsoft, VirtualBox, and others.";
            }
            enum "vhdx" {
              description
                "The VHDX disk format, an enhanced version of the
                 VHD format, which supports larger disk sizes among
                 other features.";
            }
            enum "vmdk" {
              description
                "Common disk format supported by many common virtual
                 machine monitors.";
            }
          }
          description
            "The disk format of a software image is the format of
             the underlying disk image.";
        }
        leaf min-disk {
          type uint64;
          units "Gb";
          description
            "The minimal disk size requirement for this software
             image. The value of the 'size of storage' attribute
             of the VirtualStorageDesc referencing this
             SwImageDesc shall not be smaller than the value of
             minDisk.";
          reference
            "GS NFV IFA011: Section 7.1.6.5, SwImageDesc
             information element.";
        }
        leaf min-ram {
          type decimal64 {
            fraction-digits 1;
            range "0..max";
          }
          units "Gb";
          description
            "The minimal RAM requirement for this software image.
             The value of the 'size' attribute of
             VirtualMemoryData of the Vdu referencing this
             SwImageDesc shall not be smaller than the value of
             minRam.";
          reference
            "GS NFV IFA011: Section 7.1.6.5, SwImageDesc
             information element.";
        }
        leaf size {
          type uint64;
          units "Gb";
          description
            "The size of this software image.";
          reference
            "GS NFV IFA011: Section 7.1.6.5, SwImageDesc
             information element.";
        }
        leaf image {
          mandatory true;
          type inet:uri;
          description
            "This is a reference to the actual software image.
             The reference can be relative to the root of the VNF
             Package or can be a URL";
          reference
            "GS NFV IFA011: Section 7.1.6.5, SwImageDesc
             information element.";
        }
        leaf operating-system {
          type string;
          description
            "Identifies the operating system used in the software
             image. This attribute may also identify if a 32 bit
             or 64 bit software image is used.";
          reference
            "GS NFV IFA011: Section 7.1.6.5, SwImageDesc
             information element.";
        }
        leaf-list supported-virtualization-environment {
          type string;
          description
            "Identifies the virtualisation environments
             (e.g. hypervisor) compatible with this software
             image.";
          reference
            "GS NFV IFA011: Section 7.1.6.5, SwImageDesc
             information element.";
        }
      }

      list int-virtual-link-desc {
        key "id";
        description
          "Represents the type of network connectivity mandated by the
           VNF provider between two or more CPs which includes at
           least one internal CP.";
        reference
          "GS NFV IFA011: Section 7.1.2, Vnfd information element.";
        leaf id {
          type string;
          description
            "Unique identifier of this internal VLD in VNFD.";
          reference
            "GS NFV IFA011: Section 7.1.7.2, VnfVirtualLinkDesc
             Information elements.";
        }

        list desc-flavor {
          key "id";
          description
            "Describes a specific flavour of the VL with specific
             bitrate requirements.";
          reference
            "GS NFV IFA011: Section 7.1.7.2, VnfVirtualLinkDesc
             Information elements.";

          leaf id {
            type string;
            description
              "Identifies a flavour within a VnfVirtualLinkDesc.";
            reference
              "GS NFV IFA011: Section 7.1.8.5, VirtualLinkDescFlavor
               information element.";
          }
          container qos {
            description
              "QoS of the VL.";
            reference
              "GS NFV IFA011: Section 7.1.8.5, VirtualLinkDescFlavor
               information element.";

            leaf latency {
              type uint32;
              units "ms";
              mandatory true;
              description
                "Specifies the maximum latency in ms.";
              reference
                "GS NFV IFA011: Section 7.1.8.10, QoS information
                 element.";
            }

            leaf packet-delay-variation {
              type uint32;
              units "ms";
              mandatory true;
              description
                "Specifies the maximum jitter in ms.";
              reference
                "GS NFV IFA011: Section 7.1.8.10, QoS information
                 element.";
            }

            leaf packet-loss-ratio {
              type decimal64 {
                fraction-digits "2";
                range "0..1.00";
              }
              description
                "Specifies the maximum packet loss ratio.";
              reference
                "GS NFV IFA011: Section 7.1.8.10, QoS information
                 element.";
            }
          }
        }

        uses common:connectivity-type;

        leaf-list test-access {
          type string;
          description
            "Specifies test access facilities expected on the VL
             (e.g. none, passive monitoring, or active (intrusive)
             loopbacks at endpoints.";
          reference
            "GS NFV IFA011: Section 7.1.7.2, VnfVirtualLinkDesc
             information element.";
        }
        leaf description {
          type string;
          description
            "Provides human-readable information on the purpose of
             the VL (e.g. control plane traffic).";
          reference
            "GS NFV IFA011: Section 7.1.7.2, VnfVirtualLinkDesc
             information element.";
        }
        list monitoring-parameters {
          key "id";
          leaf id {
            type string;
            description
              "Unique identifier of the monitoring parameter.";
          reference
            "GS NFV IFA011: Section 7.1.11.3, MonitoringParameter
             information element.";
          }
          uses common:monitoring-parameter;
      list ext-cpd {
        key "id";
        min-elements 1;

        description
          "Describes an external interface exposed by this VNF enabling
           connection with a Virual Link";
        reference
          "GS NFV IFA011: Section 7.1.2, VNFD information element.";

        leaf int-virtual-link-desc {
          description
            "Reference to the internal Virtual Link Descriptor (VLD)
             to which CPs instantiated from this external CP
             Descriptor (CPD) connect. Either intVirtualLinkDesc or
             intCpd shall be present.";
          type leafref {
            path "../../nfv:int-virtual-link-desc/nfv:id";
          }
        }
        /*
          intCpd
          we reference from the VDU's CP to the ext-CP instead of the
          ext-CP to the VDU's CP.
        */
        uses virtual-network-interface-requirements;
        must "nfv:default-instantiation-level or " +
             "count(nfv:instantiation-level) = 1";
        key "id";
        min-elements 1;
        description
          "Describes a specific Deployment Flavour (DF) of a VNF with
           specific requirements for capacity and performance.";
        reference
          "GS NFV IFA011: Section 7.1.2, VNFD information element.";
        leaf id {
          type string;
          description
            "Identifier of this DF within the VNFD.";
          reference
            "GS NFV IFA011: Section 7.1.8, Information elements
             to the DeploymentFlavor.";
        }
        leaf description {
          type string;
          description
            "Human readable description of the deployment flavor";
          reference
            "GS NFV IFA011: Section 7.1.8, Information elements
             to the DeploymentFlavor.";
        }
        list vdu-profile {
          key "id";
          min-elements 1;
          description
            "The Vduprofile describes additional instantiation data for
             a given VDU used in a deployment flavour.";
          reference
            "GS NFV IFA011: Section 7.1.8, Information elements
             to the DeploymentFlavor.";
          leaf id {
            type leafref {
              path "../../../nfv:vdu/nfv:id";
            }
            reference
              "GS NFV IFA011: Section 7.1.8.3, VduProfile information
               element.";
          }
          leaf min-number-of-instances {
            type uint16;
            mandatory true;
            description
              "Minimum number of instances of the VNFC based on this
               VDU that is permitted to exist for this flavour.";
            reference
              "GS NFV IFA011: Section 7.1.8.3, VduProfile information
               element.";
          }
          leaf max-number-of-instances {
            type uint16;
            mandatory true;
            must ". >= ../nfv:min-number-of-instances";
            reference
              "GS NFV IFA011: Section 7.1.8.3, VduProfile information
               element.";
          }
          uses common:local-affinity-or-anti-affinity-rule;
          list affinity-or-anti-affinity-group {
            key "id";
            description
              "Identifier(s) of the affinity or anti-affinity
               group(s) the VDU belongs to.";
            reference
              "GS NFV IFA011: Section 7.1.8.3, VduProfile information
               element.";
            leaf id {
              type leafref {
                path "../../../" +
                     "nfv:affinity-or-anti-affinity-group/" +
                     "nfv:id";
              }
              description
                "Identifies an affinity or anti-affinity group to
                  which the affinity or anti-affinity rule applies.";
              reference
                "GS NFV IFA011: Section 7.1.8.12, AffinityOrAntiAffinity
                 information element.";
            }
            leaf type {
              type enumeration {
                enum affinity;
                enum anti-affinity;
              }
              description
                "Specifies whether the rule is an affinity rule or an
                 anti-affinity rule.";
              reference
                "GS NFV IFA011: Section 7.1.8.12, AffinityOrAntiAffinity
                 information element.";
            }
            leaf scope {
              type common:affinity-scope;
              description
                "Specifies the scope of the rule, possible values are
                 'NFVI-PoP', 'Zone', 'ZoneGroup', 'NFVI-node'";
              reference
                "GS NFV IFA011: Section 7.1.8.12, AffinityOrAntiAffinity
                 information element.";
            }
          }
        }
        list virtual-link-profile {
          key "id flavor";
          description
            "Defines the internal VLD along with additional data which
             is used in this DF.";
          reference
            "GS NFV IFA011: Section 7.1.8.2, VnfDf information
             element.";

          leaf id {
            type leafref {
              path "../../../nfv:int-virtual-link-desc/nfv:id";
            }
            description
              "Uniquely identifies a Vnf VLD.";
            reference
              "GS NFV IFA011: Section 7.1.8.4, VirtualLinkProfile
               information element.";
          }
          leaf flavor {
            type leafref {
              path "deref(../../../ext-cpd/int-virtual-link-desc)" +
                   "/../desc-flavor/id";
            }
            description
              "Identifies a flavour within the VnfVirtualLinkDesc.";
            reference
              "GS NFV IFA011: Section 7.1.8.4, VirtualLinkProfile
               information element.";
          }
          uses common:local-affinity-or-anti-affinity-rule;
          list affinity-or-anti-affinity-group {
            key "id";
            leaf id {
              type leafref {
                path "../../../" +
                     "nfv:affinity-or-anti-affinity-group/" +
                     "nfv:id";
              }
            }
            description
              "Identifier(s) of the affinity or anti-affinity
               group(s) the VnfVirtualLinkDesc belongs to.";
            reference
              "GS NFV IFA011: Section 7.1.8.4, VirtualLinkProfile
               information element.";
          }
        }
        list instantiation-level {
          key "id";
          min-elements 1;
          description
            "Describes the various levels of resources that can be
             used to instantiate the VNF using this flavour.
             Examples: Small, Medium, Large. If there is only one
             'instantiationLevel' entry, it shall be treated as the
             default instantiation level for this DF.

             The InstantiationLevel information element describes a
             given level of resources to be instantiated within a
             deployment flavour in term of the number of VNFC instances
             to be created from each VDU.
             All the VDUs referenced in the level shall be part of the
             corresponding deployment flavour and their number shall
             be within the range (min/max) for this deployment flavour.";
          reference
            "GS NFV IFA011: Section 7.1.8.2 VnfDf information element";
          leaf id {
            type string;
            description
              "Uniquely identifies a level with the DF.";
            reference
              "GS NFV IFA011: Section 7.1.8.7 InstantiationLevel
               information element";
          }
          leaf description {
            type string;
            description
              "Human readable description of the instantiation level";
            reference
              "GS NFV IFA011: Section 7.1.8.7 InstantiationLevel
               information element";
          }
          list vdu-level {
            key "id";
            min-elements 1;
            description
              "Sets the number of instances for the VDU in this
               instantiation level.";
            reference
              "GS NFV IFA011: Section 7.1.8.7 InstantiationLevel
               information element";
            leaf id {
              type leafref {
                path "../../../../nfv:vdu/nfv:id";
              }
              description
                "Uniquely identifies a VDU.";
              reference
                "GS NFV IFA011: Section 7.1.8.9 VduLevel information
                 element";
            }
            leaf number-of-instances {
              type uint16;
              must ". <= ../../../../nfv:df/" +
                   "nfv:vdu-profile[id=current()/../nfv:id]/" +
                   "nfv:max-number-of-instances";
              must ". >= ../../../../nfv:df/" +
                   "nfv:vdu-profile[id=current()/../nfv:id]/" +
                   "nfv:min-number-of-instances";
              mandatory true;
              description
                "Number of instances of VNFC based on this VDU to
                 deploy for this level.";
              reference
                "GS NFV IFA011: Section 7.1.8.9 VduLevel information
                 element";
            }
          }
          list scaling-info {
            key "id";
            description
              "The InstantiationLevel information element describes a
               given level of resources to be instantiated within a
               DF in term of the number of VNFC instances to be 
               created from each VDU.";
            reference
              "GS NFV IFA011: Section 7.1.8.7 InstantiationLevel
               information element";
            leaf id {
              type leafref {
                path "../../../nfv:scaling-aspect/nfv:id";
              }
              description
                "Identifier of the scaling aspect.";
              reference
                "GS NFV IFA011: Section 7.1.8.8 ScaleInfo information
                 element";
            }
            leaf scale-level {
              type uint32;
              description
                "The scale level, greater than or equal to 0.";
              reference
                "GS NFV IFA011: Section 7.1.8.8 ScaleInfo information
                 element";
            }
          }
        }
        leaf default-instantiation-level {
          type leafref {
            path "../nfv:instantiation-level/nfv:id";
          }
          description
            "This attribute references the 'instantiationLevel'
             entry which defines the default instantiation level for
             this DF. It shall be present if there are multiple
             'instantiationLevel' entries.";
          reference
            "GS NFV IFA011: Section 7.1.8.2 VnfDf information
                 element";
        }
        leaf-list supported-operation {
          type identityref {
            base common:supported-operation;
          }
          description
            "Indicates which operations are available for this DF via
             the VNF LCM interface. Instantiate VNF, Query VNF and
             Terminate VNF are supported in all DF and therefore
             need not be included in this list.";
          reference
            "GS NFV IFA011: Section 7.1.8.2 VnfDf information
                 element";
        }
        container lcm-operations-configuration {
          description
            "This information element is a container for all
             attributes that affect the invocation of the VNF
             Lifecycle Management operations, structured by
             operation.";
          reference
            "GS NFV IFA011: Section 7.1.8.2 VnfDf information
             element";
          leaf instantiate-vnf-op-config {
            type string;
            description
              "Configuration parameters for the InstantiateVnf
               operation.";
            reference
              "GS NFV IFA011: Section 7.1.5.2
               VnfLcmOperationsConfiguration information element";
          }
          container scale-vnf-op-config {
            description
              "Configuration parameters for the ScaleVnf operation.";
            reference
              "GS NFV IFA011: Section 7.1.5.2
               VnfLcmOperationsConfiguration information element";

            list parameter {
              key "key";
              leaf key {
                type string;
              }
              leaf value {
                type string;
              }
              description
                "VNF-specific parameter to be passed when invoking
                 the ScaleVnf operation.";
              reference
                "GS NFV IFA011: Section 7.1.5.4 ScaleVnfOpConfig
                 information element";
            }
            leaf scaling-by-more-than-one-step-supported {
              type boolean;
              default false;
              description
                "Signals whether passing a value larger than one in
                 the numScalingSteps parameter of the ScaleVnf
                 operation is supported by this VNF.
                 Default is FALSE, i.e. 'not supported'.";
              reference
                "GS NFV IFA011: Section 7.1.5.4
                 ScaleVnfOpConfig information element";
            }
          }
          container scale-vnf-to-level-op-config {
            description
              "This information element defines attributes that
               affect the invocation of the ScaleVnfToLevel
               operation.";
            reference
              "GS NFV IFA011: Section 7.1.5.2
               VnfLcmOperationsConfiguration information element";

            list parameter {
              key "key";
              leaf key {
                type string;
              }
              leaf value {
                type string;
              }
              description
                "VNF-specific parameter to be passed when invoking
                 the ScaleVnfToLevel operation.";
              reference
                "GS NFV IFA011: Section 7.1.5.5
                 ScaleVnfToLevelOpConfig information element";
            }
            leaf arbitrary-target-levels-supported {
              type boolean;
              description
                "Signals whether scaling according to the parameter
                 'scaleInfo' is supported by this VNF.";
              reference
                "GS NFV IFA011: Section 7.1.5.5
                 ScaleVnfToLevelOpConfig information element";
            }
          }
          container heal-vnf-op-config {
            description
              "This information element defines attributes that
               affect the invocation of the HealVnf operation.";
            reference
              "GS NFV IFA011: Section 7.1.5.2
               VnfLcmOperationsConfiguration information element";

            leaf parameter {
              type string;
              description
                "VNF-specific parameter to be passed when invoking
                 the HealVnf operation.";
              reference
                "GS NFV IFA011: Section 7.1.5.6 HealVnfOpConfig
                 information element";
            }
            leaf cause {
              type string;
              description
                "Supported 'cause' parameter values.";
              reference
                "GS NFV IFA011: Section 7.1.5.6 HealVnfOpConfig
                 information element";
            }
          }
          container terminate-vnf-op-config {
            description
              "This information element defines attributes that
               affect the invocation of the TerminateVnf operation.";
            reference
              "GS NFV IFA011: Section 7.1.5.2
               VnfLcmOperationsConfiguration information element";
            leaf min-graceful-termination {
              type yang:timeticks;
              description
                "Minimum timeout value for graceful termination of
                 a VNF instance.";
              reference
                "GS NFV IFA011: Section 7.1.5.7
                 TerminateVnfOpConfig information element";
            }
            leaf max-recommended-graceful-termination {
              type yang:timeticks;
              description
                "Maximum recommended timeout value that can be needed
                 to gracefully terminate a VNF instance of a
                 particular type under certain conditions, such as
                 maximum load condition. This is provided by VNF
                 provider as information for the operator
                 facilitating the selection of optimal timeout value.
                 This value is not used as constraint.";
              reference
                "GS NFV IFA011: Section 7.1.5.7
                 TerminateVnfOpConfig information element";
            }
          }
          container operate-vnf-op-config {
            description
              "This information element defines attributes that 
               affect the invocation of the OperateVnf operation.";
            reference
              "GS NFV IFA011: Section 7.1.5.2
               VnfLcmOperationsConfiguration information element";

            leaf min-graceful-stop-timeout {
              type yang:timeticks;
              description
                "Minimum timeout value for graceful stop of a VNF
                 instance.";
              reference
                "GS NFV IFA011: Section 7.1.5.8
                 OperateVnfOpConfig information element";
            }
            leaf max-recommended-graceful-stop-timeout {
              type yang:timeticks;
              description
                "Maximum recommended timeout value that can be 
                 needed to gracefully stop a VNF instance of a
                 particular type under certain conditions, such as
                 maximum load condition. This is provided by VNF
                 provider as information for the operator facilitating
                 the selection of optimal timeout value. This value
                 is not used as constraint.";
              reference
                "GS NFV IFA011: Section 7.1.5.8
                 OperateVnfOpConfig information element";
            }
          }
        }
        list affinity-or-anti-affinity-group {
          key "id";
          description
            "The AffinityOrAntiAffinityGroup describes the affinity
             or anti-affinity relationship applicable between the
             virtualization containers to be created based on
             different VDUs, or between internal VLs to be created
             based on different VnfVirtualLinkDesc(s).

             Per VNF, the affinity/anti-affinity rules defined using
             this information element, using the
             LocalAffinityOrAntiAffinityRule information element, and
             using the placement constraints in the
             GrantLifecycleOperation as defined in ETSI GS NFV-IFA
             007 [i.3] should be conflict-free. In case of conflicts,
             the placement constraints in the
             GrantLifecycleOperation shall take precedence.";

          reference
            "GS NFV IFA011: Section 7.1.8.2 VnfDf information
             element";

          leaf id {
            type string;
            description
              "Identifies an affinity or anti-affinity group to which
               the affinity or anti-affinity rule applies.";
            reference
              "GS NFV IFA011: Section 7.1.8.12
               AffinityOrAntiAffinityGroup information element";
          }

          leaf type {
            mandatory true;
            type common:affinity-type;
            description
              "Specifies whether the rule is an affinity rule or an
               anti-affinity rule.";
            reference
              "GS NFV IFA011: Section 7.1.8.12
               AffinityOrAntiAffinityGroup information element";
          }

          leaf scope {
            mandatory true;
            type common:affinity-scope;
            description
              "Specifies the scope of the rule, possible values are
               'NFVI-PoP', 'Zone', 'ZoneGroup', 'NFVI-node'.";
            reference
              "GS NFV IFA011: Section 7.1.8.12
               AffinityOrAntiAffinityGroup information element";
          }
        }
        list monitoring-parameter {
          key "id";

          description
            "Defines the virtualised resources monitoring parameters
             on VNF level.";
          reference
            "GS NFV IFA011: Section 7.1.8.2 VnfDf information
             element";

          leaf id {
            type string;
            description
              "Unique identifier of the monitoring parameter.";
            reference
              "GS NFV IFA011: Section 7.1.11.3 MonitoringParameter
               information element";
          }
          uses common:monitoring-parameter;
        }

        list scaling-aspect {
          key "id";

          description
            "The scaling aspects supported by this DF of the VNF.
             scalingAspect shall be present if the VNF supports
             scaling.";
          reference
            "GS NFV IFA011: Section 7.1.8.2 VnfDf information
             element";

          leaf id {
            type string;
            description
              "Unique identifier of this aspect in the VNFD.";
            reference
              "GS NFV IFA011: Section 7.1.10.2 ScalingAspect
               information element";
          }
          leaf name {
            type string;
            description
              "Human readable name of the aspect.";
            reference
              "GS NFV IFA011: Section 7.1.10.2 ScalingAspect
               information element";
          }
          leaf description {
            type string;
            description
              "Human readable description of the aspect.";
            reference
              "GS NFV IFA011: Section 7.1.10.2 ScalingAspect
               information element";
          }
          leaf max-scale-level {
            type uint32 {
              range "1..max";
              "The maximum scaleLevel for total number of scaling
               steps that can be applied w.r.t. this aspect. The
               value of this attribute corresponds to the number of
               scaling steps can be applied to this aspect when
               scaling it from the minimum scale level (i.e. 0) to the
               maximum scale level defined by this attribute.";
            reference
              "GS NFV IFA011: Section 7.1.10.2 ScalingAspect
               information element";
          }

          container aspect-delta-details {
            list deltas {
              key "id";
              min-elements 1;

              leaf id {
                type string;
                description
                  "Identifier of this scaling delta.";
                reference
                  "GS NFV IFA011: Section 7.1.10.4 ScalingDelta
                   information element";
              }

              list vdu-delta {
                key "id";

                leaf id {
                  type leafref {
                    path "/nfv/vnfd/vdu/id";
                  }
                  description
                    "Uniquely identifies a VDU.";
                  reference
                    "GS NFV IFA011: Section 7.1.8.9 VduLevel
                     information element";
                }

                leaf number-of-instances {
                  type uint32 {
                    range "0..max";
                  }
                  description
                    "Number of instances of VNFC based on this VDU to
                     deploy for an instantiation level or for a
                     scaling delta. Shall be zero or greater.";
                  reference
                    "GS NFV IFA011: Section 7.1.8.9 VduLevel
                     information element";
                }
                description
                  "The number of VNFC instances based on particular
                   VDUs to be created or removed.";
                reference
                  "GS NFV IFA011: Section 7.1.10.4 ScalingDelta
                   information element";
              }

              list virtual-link-bit-rate-delta {
                key "id";

                leaf id {
                  type string;
                  description
                    "Uniquely identifies a VnfVirtualLinkDesc.";
                  reference
                    "GS NFV IFA011: Section 7.1.10.5
                     VirtualLinkBitRateLevel information element";
                }

                container bit-rate-requirements {
                  leaf root {
                    type uint32;
                    units bits/sec;
                    mandatory true;
                    description
                      "Throughput requirement of the link (e.g.
                       bitrate of E-Line, root bitrate of E-Tree,
                       aggregate capacity of E-LAN).";
                    reference
                      "GS NFV IFA011: Section 7.1.8.6
                       LinkBitrateRequirements information element";
                  }

                  leaf leaf {
                    type uint32;
                    units bits/sec;
                    description
                      "Throughput requirement of leaf connections to
                       the link when applicable to the connectivity
                       type (e.g. for E-Tree and E-LAN branches).";
                    reference
                      "GS NFV IFA011: Section 7.1.8.6
                       LinkBitrateRequirements information element";
                  }
                  description
                    "Bitrate requirements for an instantiation level
                     or bitrate delta for a scaling step.";
                  reference
                    "GS NFV IFA011: Section 7.1.10.5
                     VirtualLinkBitRateLevel information element";
                }
                description
                  "The bitrate to be added or removed to virtual links
                   created from particular virtual link descriptors.";
                reference
                  "GS NFV IFA011: Section 7.1.10.4 ScalingDelta
                   information element";
              }
              description
                "Declares different scaling deltas, each of which is
                 applied for one or more scaling steps of this
                 aspect.";
              reference
                "GS NFV IFA011: Section 7.1.10.3 AspectDeltaDetails
                 information element";
            }

            leaf step-deltas {
              type leafref {
                path "../deltas/id";
              }
              description
                "Identifiers of the individual scaling deltas to be
                 applied for the subsequent scaling steps of this
                 aspect. The first entry in the array shall correspond
                 to the first scaling step (between scale levels 0 to
                 1) and the last entry in the array shall correspond
                 to the last scaling step (between maxScaleLevel-1
                 and maxScaleLevel).

                 Each referenced scaling delta shall be declared in
                 the 'deltas' attribute.";