NSD: Node types

  tosca.nodes.nfv.Cp:
    derived_from: tosca.nodes.Root
    description:  Provides information regarding the purpose of the connection point 
    properties:
      layer_protocols:
        type: list
        description: Identifies which protocol the connection point uses for connectivity purposes 
        required: true
        entry_schema:
          type: string
          constraints:
            - valid_values: [ ethernet, mpls, odu2, ipv4, ipv6, pseudo-wire ]
      role: #Name in ETSI NFV IFA011 v0.7.3: cpRole
        type: string
        description: Identifies the role of the port in the context of the traffic flow patterns in the VNF or parent NS 
        required: false
        constraints:
          - valid_values: [ root, leaf ]
      description:
        type: string
        description: Provides human-readable information on the purpose of the connection point 
        required: false
      protocol:
        type: list
        description: Provides information on the addresses to be assigned to the connection point(s) instantiated from this Connection Point Descriptor 
        required: true
        entry_schema:
          type: tosca.datatypes.nfv.CpProtocolData
      trunk_mode:
        type: boolean
        description: Provides information about whether the CP instantiated from this Cp is in Trunk mode (802.1Q or other)
        required: true

  tosca.nodes.nfv.NS:
    derived_from: tosca.nodes.Root
    properties: 
      descriptor_id: 
        type: string # GUID
        description: Identifier of this NS descriptor
        required: true
      designer:
        type: string
        description: Identifies the designer of the NSD.
        required: true
      version:
        type: string
        description: Identifies the version of the NSD.
        required: true
      name:
        type: string
        description: Provides the human readable name of the NSD.
        required: true
      invariant_id:
        type: string
        description: Identifies an NSD in a version independent manner. This attribute is invariant across versions of NSD.
        required: true
    requirements:
      - virtual_link:
          capability: tosca.capabilities.nfv.VirtualLinkable
          relationship: tosca.relationships.nfv.VirtualLinksTo
          node: tosca.nodes.nfv.NsVirtualLink
          occurrences: [ 0, 1 ]
    interfaces:
      Nslcm:
        type: tosca.interfaces.nfv.Nslcm

  tosca.nodes.nfv.Sap:
    derived_from: tosca.nodes.nfv.Cp
    description: node definition of SAP.
    requirements:
      - external_virtual_link:
          capability: tosca.capabilities.nfv.VirtualLinkable
          relationship: tosca.relationships.nfv.VirtualLinksTo
      - internal_virtual_link:
          capability: tosca.capabilities.nfv.VirtualLinkable
          relationship: tosca.relationships.nfv.VirtualLinksTo