Support for OSM descriptors

[sonata-nfv]

Support for OSM descriptors

[stefanbschneider]

I'm currently creating default descriptors here.

It seems like one of the bigger differences between OSM and Tango are the connection points. 5GTANGO's network services have connection points mgmt, input, output for access from the outside:

connection_points:
  - id: "mgmt"
    interface: "ipv4"
    type: "management"
  - id: "input"
    interface: "ipv4"
    type: "external"
  - id: "output"
    interface: "ipv4"
type: "external"

Whereas OSM just connects the VNFs but does not consider input/output from the outside. See: https://osm.etsi.org/wikipub/index.php/Reference_VNF_and_NS_Descriptors_(Release_THREE)
--> Just drop input/output connection points when creating NSDs for OSM.

Also OSM just uses IDs to indentify NSDs and VNFDs, rather than vendor:name:version like in Tango

[stefanbschneider]

Also, OSM just defines the vLinks between the involved VNFs but no forwarding graph.

[stefanbschneider]

VDUs inside VNFDs are specified differently. In OSM:

• each specifies interfaces instead of connection points
• these interfaces directly map to connection points of the VNF or are connected to interfaces of other VDUs

In Tango VNF and VDU connection points are mapped using vLinks inside the VNF.

[stefanbschneider]

Started implementing the OSM generation. VNFDs are generated correctly. In NSDs the vlinks between VNFDs are still missing.