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-0.4.0-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-0.4.0-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. The following VNFD pings VDU1 with 3 ECHO packet counts, 0.2 second intervals and 2 second timeout options per monitoring trigger. Ping is attempted up to 6 times unless it returns an exit code 0. On VDU2, Tacker tries to open http://<VDU2_mgmt_ip>:80 with 2 second timeout and 6 retries. Both VDUs have 20 second delay time from creation or respawning to start monitoring. The VDUs can be re-spawned in case of failure. See Tacker Monitoring Framework for more information.

..
  VDU1:
    type: tosca.nodes.nfv.VDU.Tacker
    properties:
      monitoring_policy:
        name: ping
        parameters:
          monitoring_delay: 20
          count: 3
          interval: 0.2
          timeout: 2
          retry: 6
        actions:
          failure: respawn

  VDU2:
    type: tosca.nodes.nfv.VDU.Tacker
    properties:
      monitoring_policy:
        name: http-ping
        parameters:
          monitoring_delay: 20
          timeout: 2
          retry: 6
          port: 80
        actions:
          failure: respawn

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/0.4.0/ \
              cirros-0.4.0-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

Floating IP

Floating IP is used to access VDU from public network.

An example of assign floating ip to VDU

..
topology_template:
  node_templates:
    VDU1:
      ..
    CP1:
      type: tosca.nodes.nfv.CP.Tacker
      properties:
        management: true
      requirements:
        - virtualLink:
            node: VL1
        - virtualBinding:
            node: VDU1
    VL1:
      ..
    FIP1:
      type: tosca.nodes.network.FloatingIP
      properties:
        floating_network: public
      requirements:
        - link:
            node: CP1
type

tosca.nodes.network.FloatingIP

properties

Name

Required

Type

Constraints

Description

floating_network

Yes

String

None

Name of public network

floating_ip_address

No

String

None

Floating IP Address from public network

requirements

Name

Capability

Relationship

Description

link

tosca.capabilities .network.Linkable

tosca.relationships .network.LinksTo

States the CP node to connect to

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 VDU
       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: Tacker