VNF Forwarding Graph¶

Prerequisites¶

VNFFG with OpenStack VIM relies on Neutron Networking-sfc to create SFC and Classifiers. Therefore it is required to install networking-sfc project in order to use Tacker VNFFG. Networking-sfc also requires at least OVS 2.5 .0, so also ensure that is installed. See the full Networking-sfc guide.

A simple example of a service chain would be one that forces all traffice from HTTP client to HTTP server to go through VNFs that was created by VNFFG.

Firstly, HTTP client and HTTP server must be launched.

net_id=$(openstack network list | grep net0 | awk '{print $2}')

openstack server create --flavor m1.tiny --image cirros-0.4.0-x86_64-disk \
--nic net-id=$net_id http_client

openstack server create --flavor m1.tiny --image cirros-0.4.0-x86_64-disk \
--nic net-id=$net_id http_server

Creating the VNFFGD¶

Once OpenStack/Devstack along with Tacker has been successfully installed, deploy a sample VNFFGD template such as the one here.

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

In above example, VNFFG will have 2 flow classifier. List flow classifiers are defined in list of criteria.

You can get network_src_port_id, network_dest_port_id and destination IP address through OpenStack commands like bellow:

client_ip=$(openstack server list | grep http_client | grep -Eo '[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+')

network_source_port_id=$(openstack port list | grep $client_ip | awk '{print $2}')

ip_dst=$(openstack server list | grep http_server | grep -Eo '[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+')

network_dest_port_id=$(openstack port list | grep $ip_dst | awk '{print $2}')

This is required due to a limitation of Neutron networking-sfc and only applies to an OpenStack VIM.

Two “network_dst_port_id” and “ip_dst_prefix” parameters must be set when you want to create VNFFG with “symmetrical” feature. If you want to create VNFFG without “symmetrical”, you can ommit “network_dst_port_id” and “ip_dst_prefix”.

Forwarding_path1:
  type: tosca.nodes.nfv.FP.TackerV2
  description: creates path (CP12->CP22)
  properties:
    id: 51
    symmetrical: true
    correlation: nsh
    policy:
      type: ACL
      criteria:
        - name: block_tcp
          classifier:
            network_src_port_id: 640dfd77-c92b-45a3-b8fc-22712de480e1
            network_dst_port_id: ea206bba-7083-4364-a9f1-c0b7fdf61b6e
            ip_dst_prefix: 192.168.1.2/24
            destination_port_range: 80-1024
            ip_proto: 6
    path:
      - forwarder: VNFD1
        capability: CP12
        sfc_encap: True
      - forwarder: VNFD2
        capability: CP22
        sfc_encap: False

In above template, users can set symmetrical in properties of a forwarding path create symmetrical VNFFG. If this property is not set, symmetrical will be specified by –symmetrical in create VNFFG command (default value is False).

In other hand, by setting correlation in properties let users can choose SFC encapsulation between MPLS or NSH (default: MPLS). If sfc_encap is True, port pair’s correlation is set to same value with correlation to make use of correlation that SFC Encapsulation provides, otherwise port pair’s correlation is set to None to install SFC proxy SFC_PROXY. Detailed information about SFC encapsulation can be found in Networking-SFC project SFC_ENCAPSULATION

You can use the sample VNFFGD template for symmetrical feature (in port chain) such as this link.

The symmetrical argument is used to indicate if reverse traffic should also flow through the path. This creates an extra classifier to ensure return traffic flows through the chain in a reverse path, otherwise this traffic routed normally and does not enter the VNFFG.

Tacker provides the following OpenStackClient CLI to create a VNFFGD:

openstack vnf graph descriptor create --vnffgd-file <vnffgd-file> <vnffgd-name>

Creating the VNFFG¶

To create a VNFFG, you must have first created VNF instances of the same VNFD types listed in the VNFFGD. Failure to do so will result in error when trying to create a VNFFG. Note, the VNFD you define must include the same Connection Point definitions as the ones you declared in your VNFFGD.

openstack vnf descriptor create --vnfd-file tosca-vnffg-vnfd1.yaml VNFD1
openstack vnf create --vnfd-name VNFD1 VNF1

openstack vnf descriptor create --vnfd-file tosca-vnffg-vnfd2.yaml VNFD2
openstack vnf create --vnfd-name VNFD2 VNF2

Refer the ‘Getting Started’ link below on how to create a VNFD and deploy 2 VNFs: VNF1 and VNF2.

https://docs.openstack.org/tacker/latest/install/getting_started.html

Tacker provides the following OpenStackClient CLI to create VNFFG from VNFFGD:

openstack vnf graph create --vnffgd-name <vnffgd-name> --vnf-mapping <vnf-mapping> --symmetrical <vnffg-name>

or you can create directly VNFFG from vnffgd template without initiating VNFFGD.

openstack vnf graph create --vnffgd-template <vnffgd-template> --vnf-mapping <vnf-mapping> \
--symmetrical <vnffg-name>

If you use a parameterized vnffg template:

openstack vnf graph create --vnffgd-name <vnffgd-name> --param-file <param-file> --vnf-mapping <vnf-mapping> \
--symmetrical <vnffg-name>

Here,

• vnffgd-name - VNFFGD to use to instantiate this VNFFG
• param-file - Parameter file in Yaml.
• vnf-mapping - Allows a list of logical VNFD to VNF instance mapping
• symmetrical - If –symmetrical is present, symmetrical is True (default: False - The symmectical is set in template has higher priority)

VNF Mapping is used to declare which exact VNF instance to be used for each VNF in the Forwarding Path. The following command would list VNFs in Tacker and then map each VNFD defined in the VNFFGD Forwarding Path to the desired VNF instance:

openstack vnf list

+--------------------------------------+------+---------------------------+--------+--------------------------------------+--------------------------------------+
| id                                   | name | mgmt_ip_address           | status | vim_id                               | vnfd_id                              |
+--------------------------------------+------+---------------------------+--------+--------------------------------------+--------------------------------------+
| 7168062e-9fa1-4203-8cb7-f5c99ff3ee1b | VNF2 | {"VDU1": "192.168.1.5"}   | ACTIVE | 0e70ec23-6f32-420a-a039-2cdb2c20c329 | ea842879-5a7a-4f29-a8b0-528b2ad3b027 |
| 91e32c20-6d1f-47a4-9ba7-08f5e5effe07 | VNF1 | {"VDU1": "192.168.1.7"}   | ACTIVE | 0e70ec23-6f32-420a-a039-2cdb2c20c329 | 27795330-62a7-406d-9443-2daad76e674b |
+--------------------------------------+------+---------------------------+--------+--------------------------------------+--------------------------------------+

openstack vnf graph create --vnffgd-name myvnffgd --vnf-mapping \
VNFD1:'91e32c20-6d1f-47a4-9ba7-08f5e5effe07',VNFD2:'7168062e-9fa1-4203-8cb7-f5c99ff3ee1b' --symmetrical myvnffg

Alternatively, if no vnf-mapping is provided then Tacker VNFFG will attempt to search for VNF instances derived from the given VNFDs in the VNFFGD. If multiple VNF instances exist for a given VNFD, the VNF instance chosen to be used in the VNFFG is done at random.

Parameters for VNFFGD template¶

Similar to TOSCA VNFD template, any value of VNFFGD template can be parameterized. Once parameterized different values can be passed while instantiating the forwarding graph using the same VNFFGD template. The value of a parameterized attribute can be specified like {get_input foo} in the TOSCA VNFFGD template. The corresponding param-file in the following YAML format can be provided in the vnffg-create command,

{
  foo: bar
}

VNFFG command with parameter file:

openstack vnf graph create --vnffgd-name vnffgd-param --vnf-mapping VNFD1:'91e32c20-6d1f-47a4-9ba7-08f5e5effe07',\
VNFD2:'7168062e-9fa1-4203-8cb7-f5c99ff3ee1b' --param-file vnffg-param-file.yaml myvnffg

See VNFFGD template samples with parameter support.

Viewing a VNFFG¶

A VNFFG once created is instantiated as multiple sub-components. These components include the VNFFG itself, which relies on a Network Forwarding Path (NFP). The NFP is then composed of a Service Function Chain (SFC) and a Classifier. The main command to view a VNFFG is ‘openstack vnf graph show’, however there are several commands available in order to view the sub-components for a rendered VNFFG:

openstack vnf network forwarding path list
openstack vnf network forwarding path show <nfp id>
openstack vnf chain list
openstack vnf chain show <chain id>
openstack vnf classifier list
openstack vnf classifier show <classifier id>

Updating the VNFFG¶

To update an already created VNFFG template the user needs to locate the VNFFG which wants to update. To do so the following command is getting executed:

Using the below command query the list of existing VNFFG templates.

openstack vnf graph list

+--------------------+---------+--------+-------------------------------------+
|    ID              | Name    | Status | VNFFGD ID                           |
+--------------------+------------------+-------------------------------------+
| f4438511-e33d-43df-|         |        |                                     |
| 95d9-0199253db72e  | myvnffg | ACTIVE | bd7829bf-85de-4f3b-960a-8482028bfb34|
+--------------------+---------+--------+-------------+--------+--------------+

To verify result, user can get information of port chain in networking-sfc:

$ openstack sfc port chain list --fit-width

+-----------------------+-------------------+-----------------------+-----------------------+-----------------------+----------+
| ID                    | Name              | Port Pair Groups      | Flow Classifiers      | Chain Parameters      | Chain ID |
+-----------------------+-------------------+-----------------------+-----------------------+-----------------------+----------+
| 60d1a3ee-8455-415e-   | VNFFG1-port-chain | [u'87d7d4c2-d2d1-4a99 | [u'02fa422c-9f40-4092 | {u'symmetric': False, |       51 |
| 8ff1-e0b6b9f9f277     |                   | -81fb-f3d5f51dd919',  | -a8b0-c04355116e5e']  | u'correlation':       |          |
|                       |                   | u'81213b4c-0e5e-445d- |                       | u'nsh'}               |          |
|                       |                   | add6-dea2bf55078f']   |                       |                       |          |
+-----------------------+-------------------+-----------------------+-----------------------+-----------------------+----------+

After the user located the VNFFG the subsequent action is to update it. Based on the appropriate choice, update VNFFG template. Currently two choices are supported for the update of an existing VNFFG. The first choice is the use of the vnf-mapping parameter. The user needs to use a VNF which is actually derived from the VNFD which is going to be used in the vnf-mapping parameter. If the user is not sure which VNF was used for the mapping during the time of the VNFFG creation he can execute:

Execute the below command to query the VNF that was used in mapping at the time of VNFFG creation.

openstack vnf graph show myvnffg

After user determined which VNF is used and which VNF is going to be used in the update procedure he can execute:

To update the VNF mappings to VNFFG, execute the below command

openstack vnf graph set --vnf-mapping VNFD1:vnf1,VNFD2:vnf2 myvnffg

Updated vnffg: myvnffg

The second choice is the use of the vnffgd-template parameter. The aforementioned parameter provides the ability to use a vnffgd formated yaml template which contains all the elements and their parameters that Tacker is going to apply to its ecosystem.

Below there is an example usage of updating an existing VNFFG:

Assuming that the existing VNFFG in the system that we want to update is derived from the following VNFFGD template.

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 (CP1)
      properties:
        id: 51
        symmetrical: false
        policy:
          type: ACL
          criteria:
            - name: block_udp
              classifier:
                destination_port_range: 80-1024
                ip_proto: 17
        path:
          - forwarder: VNFD3
            capability: CP1

  groups:
    VNFFG1:
      type: tosca.groups.nfv.VNFFG
      description: UDP to Corporate Net
      properties:
        vendor: tacker
        version: 1.0
        number_of_endpoints: 1
        dependent_virtual_link: [VL1]
        connection_point: [CP1]
        constituent_vnfs: [VNFD3]
      members: [Forwarding_path1]

By using the below VNFFGD template we can update the exisitng VNFFG.

tosca_definitions_version: tosca_simple_profile_for_nfv_1_0_0

description: Sample VNFFG template

topology_template:

  node_templates:

    Forwarding_path2:
      type: tosca.nodes.nfv.FP.TackerV2
      description: creates path (CP1->CP2)
      properties:
        id: 52
        symmetrical: false
        correlation: nsh
        policy:
          type: ACL
          criteria:
            - name: block_tcp
              classifier:
                network_src_port_id: 640dfd77-c92b-45a3-b8fc-22712de480e1
                destination_port_range: 22-28
                ip_proto: 6
                ip_dst_prefix: 192.168.1.2/24
        path:
          - forwarder: VNFD1
            capability: CP1
            sfc_encap: True
          - forwarder: VNFD2
            capability: CP2
            sfc_encap: False

  groups:
    VNFFG1:
      type: tosca.groups.nfv.VNFFG
      description: SSH to Corporate Net
      properties:
        vendor: tacker
        version: 1.0
        number_of_endpoints: 2
        dependent_virtual_link: [VL1,VL2]
        connection_point: [CP1,CP2]
        constituent_vnfs: [VNFD1,VNFD2]
      members: [Forwarding_path2]

The above template informs Tacker to update the current classifier,NFP and path (chain) with the ones that are described in that template. After the completion of the update procedure the new NFP will be named ‘Forwarding_path2’ with an id of ‘52’,the classifier in that NFP will be named ‘block_tcp’ and will have the corresponding match criteria and the updated chain will be consisted by two NVFs which are derived from VNFD1,VNFD2 VNFDs.

To update the existing VNFFG through the vnffgd-template parameter, execute the below command:

openstack vnf graph set --vnffgd-template myvnffgd.yaml myvnffg

Updated vnffg: myvnffg

Of course the above update VNFFG’s choices can be combined in a single command.

openstack vnf graph set --vnf-mapping VNFD1:vnf1,VNFD2:vnf2 --vnffgd-template myvnffgd.yaml myvnffg

Updated vnffg: myvnffg

Known Issues and Limitations¶

• Match criteria requires ‘network_src_port_id’
• Only one Forwarding Path allowed per VNFFGD
• Matching on criteria with postfix ‘name’ does not work, for example ‘network_name’
• NSH attributes not yet supported
• n-sfc Bug: https://bugs.launchpad.net/networking-sfc/+bug/1746686