Fabric Crossconnect Service

The Fabric Crossconnect service creates an L2 bridge between two given ports on the same device. For example, this service can be used on a SEBA pod to connect OLT devices to a BNG via the aggregation switch.

A fabric crossconnect entry is a tuple (deviceid, vlanid, port1, port2).

For more information, see VLAN Cross Connect

Models

This service is comprised of three models:

• FabricCrossconnectService global service-related parameters, such as the name of the service. There is currently no additional state here beyond the default XOS Service model.
• FabricCrossconnectServiceInstance represents one half of a vlan crossconnect. Fields include the following:
  • s-tag the vlan_id that will be connected
  • switch_datapath_id switch id where the vlan crossconnect will be enacted
  • source_port port number on the switch
• BNGPortMapping represents the other half of a vlan crossconnect. Fields include the following:
  • s_tag the vlan_id that will be connected. In addition to specifying a single vlan_id, the keyword ANY may be used, or a range (123-456) may be used.
  • switch_port port number on the switch

FabricCrossconnectServiceInstance and BNGPortMapping work together to create the vlan crossconnect tuple, linked by a common s-tag.

Example TOSCA

Below is an example TOSCA recipe that creates a FabricCrossconnectServiceInstance:

tosca_definitions_version: tosca_simple_yaml_1_0
imports:
  - custom_types/fabriccrossconnectservice.yaml
  - custom_types/fabriccrossconnectserviceinstance.yaml
description: Create a FabricCrossconnectServiceInstance
topology_template:
  node_templates:
    service#fabric-crossconnect:
      type: tosca.nodes.FabricCrossconnectService
      properties:
        name: fabric-crossconnect
        must-exist: true

    fcsi:
      type: tosca.nodes.FabricCrossconnectServiceInstance
      properties:
        name: "custom_vm_crossconnect"
        s_tag: 123
        source_port: 3
        switch_datapath_id: "of:0000000000000201"
      requirements:
        - owner:
            node: service#fabric-crossconnect
            relationship: tosca.relationships.BelongsToOne

Below is an example TOSCA recipe that creates a BNGPortMapping for a single s-tag:

tosca_definitions_version: tosca_simple_yaml_1_0
imports:
  - custom_types/bngportmapping.yaml
description: Create a bng port mapping
topology_template:
  node_templates:
    bngmapping:
      type: tosca.nodes.BNGPortMapping
      properties:
        s_tag: "222"
        switch_port: 4

Integration with other Services

The western neighbor of the FabricCrossconnectService is typically an access service such as VOLTService. FabricCrossconnectServiceInstance participates in the dataplane chain for a given subscriber.

FabricCrossConnectService features a method acquire_service_instance(subscriber_service_instance) that may be used as a helper for creating service instances. Given that many subscribers may map to a single s_tag, it's often the case that a single FabricCrossconnectServiceInstance is used by several subscribers. acquire_service_instance does the following:

1. Check to see if an eligible FabricCrossconnnectServiceInstance already exists, and if so links it to the subscriber_service_instance.
2. If no eligible FabricCrossconnectServiceInstance already exists, then a new one will be created and linked.

Synchronization workflow

FabricCrossconnectServiceInstance

When a FabricCrossconnectServiceInstance is created, updated, or deleted, the synchronizer will make a REST API call to ONOS.

BNGPortMapping

No specific processing is performed if a BNGPortMapping is created, updated, or deleted, as the workflow is driven by FabricCrossconnectServiceInstance. Responding to changes in BNGPortMapping is future work. For now it is suggested that if you need to change one, afterward you touch any FabricCrossconnectServiceInstance that may be affected, causing them to resynchronize.