Port Binding API¶

Problem Description¶

MidoNet does not currently provide a way to bind ports in Neutron using standard Neutron API.

Proposed Change¶

Use the existing ‘binding’ extension API in Neutron to implement port binding in MidoNet.

To bind a port to a specific host interface, an operator makes a ‘create_port’ API request to Neutron and provide the following binding details:

• ‘binding:host_id’: ID of the host to bind the port on
• ‘binding:profile[“interface_name”]’: Name of the interface to bind the port

The host ID is stored in the ‘portbindings’ table, and the interface name is stored in the ‘midonet_portbindings’ table. When the host ID and the interface name are supplied in the port creation request, the MidoNet executes the binding within the same API request.

Updating a port with a different binding effectively unbinds the port and re-binds it to the new host interface.

In the case of VM port binding, the workflow is as follows:

1. Nova API makes a ‘create_port’ request to Neutron API specifying the ID of the host(‘host_id’) where the VM is going to be placed. ‘host_id’ is stored in Neutron’s ‘portbindings’ table.
2. Neutron generates the tap interface name the same way Nova does (‘tap’ + portID up to 14 chars), and stores it in the ‘midonet_portbindings’ table.
3. On the compute host, ‘mm-ctl’ script is executed to do the actual binding. ‘mm-ctl’ adds a port binding task to signal to MidoNet that the binding should occur. This step may change in the future.

For each scenario in which a port binding occurs, the plugin inserts a PORTBINDING task with ‘resource_id’ set to the ID of the port getting bound.

The actual mechanism in which the binding takes place inside MidoNet is outside the scope of this document.

{
  "binding:host_id": "HOST_ID",
  "binding:profile": {"interface_name": "eth0"}
}

neutron port-create [--binding:host_id HOST_ID]
                    [--binding:profile if_name=IF_NAME]