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VNFFG Descriptor Template Guide

Overview

This document explains VNFFGD template structure and its various fields based on TOSCA standards V1.0¹.

For VNFFG usage, please refer to the document available at².

The behavioural and deployment information of a VNFFG in Tacker is defined in a template known as VNFFG Descriptor (VNFFGD). The template is based on TOSCA standards and is written in YAML. It is on-boarded in a VNFFG catalog.

Each VNFFGD template will have below fields:

tosca_definitions_version:
   This defines the TOSCA definition version on which the template is based.
   The current version being tosca_simple_profile_for_nfv_1_0_0.

tosca_default_namespace:
   This is optional. It mentions default namespace which includes schema,
   types version etc.

description:
   A short description about the template.

metadata:
   template_name: A name to be given to the template.

topology_template:
   Describes the topology of the VNFFG under node_template field.
   node_template:
       Describes node types of a VNFFG.
       FP:
           Describes properties and path of a Forwarding Path.
   groups:
       Describes groupings of nodes that have an implied relationship.
       VNFFG:
           Describes properties and members of a VNF Forwarding Graph.

For examples, please refer sample VNFFGD templates available at GitHub³.

Node types

For Tacker purposes a VNFFGD only includes Forwarding Path. In a full Network Services Descriptor (NSD), it would include information about each VNFD as well. However until that implementation, VNFD is described in a separate template. Only a single Forwarding Path is currently supported. node_templates is a child of topology_template.

Forwarding Path

Forwarding Path is a required entry in a VNFFGD. It describes the chain as well as the classifier that will eventually be created to form a path through a set of VNFs.

type: tosca.nodes.nfv.FP.Tacker
properties: Describes the properties of a FP. These include id (path ID), policy (traffic match policy to flow through the path), and path (chain of VNFs/Connection Points). A complete list of VNFFG properties currently supported by Tacker are listed here⁴ under properties section of tosca.nodes.nfv.FP.TackerV2 field.

Specifying FP properties

An example FP shown below:

node_templates:

  Forwarding_path1:
    type: tosca.nodes.nfv.FP.TackerV2
    description: creates path (CP12->CP22)
    properties:
      id: 51
      policy:
        type: ACL
        criteria:
          - name: block_tcp
            classifier:
              network_src_port_id: 640dfd77-c92b-45a3-b8fc-22712de480e1
              destination_port_range: 80-1024
              ip_proto: 6
              ip_dst_prefix: 192.168.1.2/24
        path:
          - forwarder: VNFD1
            capability: CP12
          - forwarder: VNFD2
            capability: CP22

Or, you can add more named classifiers like below since the current Tacker's TOSCA template support multiple named classifiers

node_templates:

  Forwarding_path1:
    type: tosca.nodes.nfv.FP.TackerV2
    description: creates path (CP12->CP22)
    properties:
      id: 51
      policy:
        type: ACL
        criteria:
          - name: block_tcp
            classifier:
              network_src_port_id: 640dfd77-c92b-45a3-b8fc-22712de480e1
              destination_port_range: 80-1024
              ip_proto: 6
              ip_dst_prefix: 192.168.1.2/24
          - name: block_udp
            classifier:
              network_src_port_id: 640dfd77-c92b-45a3-b8fc-22712de480eda
              destination_port_range: 80-1024
              ip_proto: 17
              ip_dst_prefix: 192.168.2.2/24
        path:
          - forwarder: VNFD1
            capability: CP12
          - forwarder: VNFD2
            capability: CP22

id

ID from the above example is used to identify the path. This path ID will be used in future implementations of Network Service Header (NSH) to identify paths via the Service Path Identifier (SPI) attribute.

policy

Policy defines the type of match policy that will be used to distinguish which traffic should enter this Forwarding Path. The only currently supported type is ACL (access-list). Please reference tosca.nfv.datatypes.aclType⁵ under properties section for more information on supported match criteria.

path

Path defines an ordered list of nodes to traverse in a Forwarding Path. Each node is really a logical port, which is defined in the path as a Connection Point (CP) belonging to a specific VNFD. It is not necessary at VNFFGD creation time to have predefined these VNFDs used in the path. They may be created later. Up to 2 CPs may be listed (in order) per VNFD. If 2 are listed, the first will be considered the ingress port for traffic and the second will be the egress. If only one port is provided, then it will be interpreted as both the ingress and egress port for traffic.

Groups

In Tacker and TOSCA, the VNFFG itself is described in this section. There may only be a single VNFFG described in each VNFFGD under this section.

VNFFG

VNFFG maps the Forwarding Path to other node types defined in the properties section.

type: tosca.groups.nfv.VNFFG
properties: Describes the properties of a VNFFG. These include vendor, version, dependent_virtual_link, connection_points, constituent_vnfs. . A complete list of VNFFG properties currently supported by Tacker are listed in TOSCA⁶.
members: A list of Forwarding Paths which belong to this VNFFG. At the moment only one is supported.

Specifying VNFFG properties and members

An example VNFFG shown below:

groups:
  VNFFG1:
    type: tosca.groups.nfv.VNFFG
    description: HTTP to Corporate Net
    properties:
      vendor: tacker
      version: 1.0
      number_of_endpoints: 2
      dependent_virtual_link: [VL1,VL2,VL3]
      connection_point: [CP1,CP2]
      constituent_vnfs: [VNF1,VNF2]
    members: [Forwarding_path1]

number_of_endpoints

Number of CPs included in this VNFFG.

dependent_virtual_link

The Virtual Link Descriptors (VLD) that connect each VNF/CP in this Forwarding Graph.

connection_point

List of Connection Points defined in the Forwarding Path.

constituent_vnfs

List of VNFD names used in this Forwarding Graph (also defined in Forwarding Path).

Summary

To summarize VNFFGD is written in YAML and describes a VNFFG topology. It is composed of a Forwarding Path and a VNFFG. A full VNFFGD is shown below:

tosca_definitions_version: tosca_simple_profile_for_nfv_1_0_0

description: Sample VNFFG template

topology_template:

  node_templates:

    Forwarding_path1:
      type: tosca.nodes.nfv.FP.TackerV2
      description: creates path (CP12->CP22)
      properties:
        id: 51
        policy:
          type: ACL
          criteria:
            - name: block_tcp
              classifier:
                network_src_port_id: 640dfd77-c92b-45a3-b8fc-22712de480e1
                destination_port_range: 80-1024
                ip_proto: 6
                ip_dst_prefix: 192.168.1.2/24
        path:
          - forwarder: VNFD1
            capability: CP12
          - forwarder: VNFD2
            capability: CP22

  groups:
    VNFFG1:
      type: tosca.groups.nfv.VNFFG
      description: HTTP to Corporate Net
      properties:
        vendor: tacker
        version: 1.0
        number_of_endpoints: 2
        dependent_virtual_link: [VL12,VL22]
        connection_point: [CP12,CP22]
        constituent_vnfs: [VNFD1,VNFD2]
      members: [Forwarding_path1]

Footnotes

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