VNF Descriptor Template Guide

Overview

This document explains VNFD template structure and its various fields based on TOSCA standards V1.0 CSD 03.

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

Each VNFD 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 VNF under node_template field.
   node_template:
       Describes node types of a VNF.
       VDU:
           Describes properties and capabilities of Virtual Deployment
           Unit.
       CP:
           Describes properties and capabilities of Connection Point.
       VL:
           Describes properties and capabilities of Virtual Link.

For examples, please refer sample VNFD templates available at GitHub.

Node types

A VNF includes VDU/s, connection point/s and virtual link/s. Hence a valid VNFD must have these 3 components. Each component is referred as a node and can have certain type, capabilities, properties, attributes and requirements. These components are described under node_templates in the VNFD template. node_templates is a child of topology_template.

VDU

Virtual Deployment Unit is a basic part of VNF. It is the VM that hosts the network function.

type:tosca.nodes.nfv.VDU.Tacker properties:Describes the properties like image to be used in VDU, availability zone in which VDU is to be spawned, management driver to be used to manage the VDU, flavor describing physical properties for the VDU to be spawned, monitoring policies for the VDU, providing user data in form of custom commands to the VDU. A complete list of VDU properties currently supported by Tacker are listed here under properties section of tosca.nodes.nfv.VDU.Tacker field

Specifying VDU properties

A very simple VDU with 10 GB disk, 2 GB RAM, 2 CPUs, cirros image and in nova availability zone can be described as:

topology_template:
  node_templates:
    VDU1:
      type: tosca.nodes.nfv.VDU.Tacker
      properties:
        image: cirros-0.3.5-x86_64-disk
        availability_zone: nova
      capabilities:
        nfv_compute:
          properties:
            disk_size: 10 GB
            mem_size: 2048 MB
            num_cpus: 2

Using Nova flavors for VDU

OpenStack specific flavors can also be used to describe VDU configuration.

topology_template:
  node_templates:
    VDU1:
      type: tosca.nodes.nfv.VDU.Tacker
      properties:
        image: cirros-0.3.5-x86_64-disk
        flavor: m1.tiny
        availability_zone: nova

However, when both nfv_compute properties and flavor are mentioned in a VNFD, flavor setting will take precedence.

Monitoring the VDU

A VDU can be monitored by pinging it on port 22 for 3 times at an interval of 2 seconds every 20 seconds. Number of retries be 6 and timeout of 2 seconds. It can be re-spawned in case ping fails. This is described under monitoring_policy.

..
  VDU1:
    type: tosca.nodes.nfv.VDU.Tacker
    properties:
      monitoring_policy:
        name: ping
          parameters:
            monitoring_delay: 20
            count: 3
            interval: 2
            timeout: 2
            actions:
              failure: respawn
            retry: 6
            port: 22

Providing user data

Custom commands to be run on VDU once it is spawned can be specified in a VNFD template as user data.

..
  VDU1:
    type: tosca.nodes.nfv.VDU.Tacker
    properties:
      user_data_format: RAW
      user_data: |
        #!/bin/sh
        echo "Adding this line to demofile" > /tmp/demofile

Configuring a VDU

A VDU can be configured as a specific Network Function under config section in VNFD template. A sample template configuring a VDU as a firewall can be viewed in a sample file.

Specifying external image

artifacts:To specify an image via a file or an external link

An image URL can be specified as artifacts. Tacker will specify the image location in HOT (Heat Template) and pass it to heat-api. Heat will then spawn the VDU with that image.

..
  VDU1:
    type: tosca.nodes.nfv.VDU.Tacker
    artifacts:
      VNFImage:
        type: tosca.artifacts.Deployment.Image.VM
        file: http://download.cirros-cloud.net/0.3.5/ \
              cirros-0.3.5-x86_64-disk.img

VDU Capabilities

Computational properties of a VDU are described as its capabilities. Allocated RAM size, allocated disk size, memory page size, number of CPUs, number of cores per CPU, number of threads per core can be specified.

A VDU with 10 GB disk, 2 GB RAM, 2 CPUs, 4 KB of memory page and dedicated CPU can be specified as below. Thread and core counts can be specified as shown.

..
  VDU1:
    type: tosca.nodes.nfv.VDU.Tacker
    capabilities:
      nfv_compute:
        properties:
          disk_size: 10 GB
          mem_size: 2048 MB
          num_cpus: 2
          mem_page_size: small
          cpu_allocation:
            cpu_affinity: dedicated
            thread_count: 4
            core_count: 2

capabilities:

Name	Type	Constraints	Description
nfv_compute	Compute. Container. Architecture	None	Describes the configurat ion of the VM on which the VDU resides

Compute Container Architecture

type:tosca.capabilities.Compute.Container.Architecture properties:

Name	Required	Type	Constraints	Description
mem_page_size (in MB)	No	String	One of below small large any (default) custom	Indicates page size of the VM small maps to 4 KB large maps to 2 MB any maps to system’s default custom sets the size to specified value
cpu_allocation	No	CPUAllo- cation		CPU allocation requirement like dedicated CPUs, socket/thread count
numa_node_count	No	Integer		Symmetric count of NUMA nodes to expose to VM. vCPU and Memory is split equally across this number of NUMA
numa_nodes	No	Map of NUMA	Symmetric numa_node_count should not be specified	Asymmetric allocation of vCPU and memory across the specified NUMA nodes

CPUAllocation

This describes the granular CPU allocation requirements for VDUs.

type:tosca.datatypes.compute.Container.Architecture.CPUAllocation properties:

Name	Type	Constraints	Description
cpu_affinity	String	One of shared dedicated	Describes whether vCPU need to be pinned to dedicated CPU core or shared dynamically
thread_allocation	String	One of avoid separate isolate prefer	Describes thread allocation requirement
socket_count	Integer	None	Number of CPU sockets
core_count	Integer	None	Number of cores per socket
thread_count	Integer	None	Number of threads per core

NUMA architecture

Following code snippet describes symmetric NUMA topology requirements for VDUs.

..
VDU1:
  capabilities:
    nfv_compute:
      properties:
        numa_node_count: 2
        numa_nodes: 3

For asymmetric NUMA architecture:

..
VDU1:
  capabilities:
    nfv_compute:
      properties:
        mem_size: 4096 MB
        num_cpus: 4
        numa_nodes:
          node0:
            id: 0
            vcpus: [0,1]
            mem_size: 1024 MB
          node1:
            id: 1
            vcpus: [2,3]
            mem_size: 3072 MB

type:tosca.datatypes.compute.Container.Architecture.NUMA properties:

Name	Type	Constraints	Description
id	Integer	>= 0	CPU socket identifier
vcpus	Map of integers	None	List of specific host cpu numbers within a NUMA socket complex
mem_size	scalar- unit.size	>= 0MB	Size of memory allocated from this NUMA memory bank

Connection Points

Connection point is used to connect the internal virtual link or outside virtual link. It may be a virtual NIC or a SR-IOV NIC. Each connection point has to bind to a VDU. A CP always requires a virtual link and a virtual binding associated with it.

A code snippet for virtual NIC (Connection Point) without anti-spoof protection and are accessible by the user. CP1 and CP2 are connected to VDU1 in this order. Also CP1/CP2 are connected to VL1/VL2 respectively.

..
topology_template:
  node_templates:
    VDU1:
      ..
    CP1:
      type: tosca.nodes.nfv.CP.Tacker
      properties:
        mac_address: fa:40:08:a0:de:0a
        ip_address: 10.10.1.12
        type: vnic
        anti_spoofing_protection: false
        management: true
        order: 0
        security_groups:
          - secgroup1
          - secgroup2
      requirements:
        - virtualLink:
            node: VL1
        - virtualBinding:
            node: VDU1
    CP2:
      type: tosca.nodes.nfv.CP.Tacker
      properties:
        type: vnic
        anti_spoofing_protection: false
        management: true
        order: 1
      requirements:
        - virtualLink:
            node: VL2
        - virtualBinding:
            node: VDU1
    VL1:
      ..
    VL2:
      ..

type:tosca.nodes.nfv.CP.Tacker properties:

Name	Required	Type	Constraints	Description
type	No	String	One of vnic (default) sriov	Specifies the type of CP
anti_spoofing_protection	No	Boolean	None	Indicates whether anti_spoof rule is enabled for the VNF or not. Applicable only when CP type is virtual NIC
management	No	Boolean	None	Specifies whether the CP is accessible by the user or not
order	No	Integer	>= 0	Uniquely numbered order of CP within a VDU. Must be provided when binding more than one CP to a VDU and ordering is required.
security_groups	No	List	None	List of security groups to be associated with the CP
mac_address	No	String	None	The MAC address
ip _address	No	String	None	The IP address

requirements:

Name	Capability	Relationship	Description
virtualLink	nfv.VirtualLinkable	nfv.VirtualLinksTo	States the VL node to connect to
virtualbinding	nfv.VirtualBindable	nfv.VirtualBindsTo	States the VDU node to connect to

Virtual Links

Virtual link provides connectivity between VDUs. It represents the logical virtual link entity.

An example of a virtual link whose vendor is Acme and is attached to network net-01 is as shown below.

..
topology_template:
  node_templates:
    VDU1:
      ..
    CP1:
      ..
    VL1:
      type: tosca.nodes.nfv.VL
      properties:
        vendor: Acme
        network_name: net-01

type:tosca.nodes.nfv.VL properties:

Name	Required	Type	Constraints	Description
vendor	Yes	String	None	Vendor generating this VL
network_name	Yes	String	None	Name of the network to which VL is to be attached

Multiple nodes

Multiple node types can be defined in a VNFD.

..
topology_template:
  node_templates:
    VDU1:
      ..
    VDU2:
      ..
    CP1:
      ..
    CP2:
      ..
    VL1:
      ..
    VL2:
      ..

Summary

To summarize VNFD is written in YAML and describes a VNF topology. It has three node types, each with different capabilities and requirements. Below is a template which mentions all node types with all available options.

tosca_definitions_version: tosca_simple_profile_for_nfv_1_0_0
description: Sample VNFD template mentioning possible values for each node.
metadata:
 template_name: sample-tosca-vnfd-template-guide
topology_template:
 node_templates:
   VDU:
     type: tosca.nodes.nfv.VDU.Tacker
     capabilities:
       nfv_compute:
         properties:
           mem_page_size: [small, large, any, custom]
           cpu_allocation:
             cpu_affinity: [shared, dedicated]
             thread_allocation: [avoid, separate, isolate, prefer]
             socket_count: any integer
             core_count: any integer
             thread_count: any integer
           numa_node_count: any integer
           numa_nodes:
             node0: [ id: >=0, vcpus: [host CPU numbers], mem_size: >= 0MB]
     properties:
       image: Image to be used in VM
       flavor: Nova supported flavors
       availability_zone: available availability zone
       mem_size: in MB
       disk_size: in GB
       num_cpus: any integer
       metadata:
         entry_schema:
       config_drive: [true, false]
       monitoring_policy:
         name: [ping, noop, http-ping]
         parameters:
           monitoring_delay: delay time
           count: any integer
           interval: time to wait between monitoring
           timeout: monitoring timeout time
           actions:
             [failure: respawn, failure: terminate, failure: log]
           retry: Number of retries
           port: specific port number if any
       config: Configuring the VDU as per the network function requirements
       mgmt_driver: [default=noop]
       service_type: type of network service to be done by VDU
       user_data: custom commands to be executed on VDU
       user_data_format: format of the commands
       key_name: user key
     artifacts:
       VNFImage:
         type: tosca.artifacts.Deployment.Image.VM
         file: file to be used for image
   CP:
     type: tosca.nodes.nfv.CP.Tacker
     properties:
       management: [true, false]
       anti_spoofing_protection: [true, false]
       type: [ sriov, vnic ]
       order: order of CP within a VDU
       security_groups: list of security groups
     requirements:
       - virtualLink:
          node: VL to link to
       - virtualBinding:
          node: VDU to bind to
   VL:
     type: tosca.nodes.nfv.VL
     properties:
       network_name: name of network to attach to
       vendor: Acme