4. Port data plane status


Neutron does not detect data plane failures affecting its logical resources. This spec addresses that issue by means of allowing external tools to report to Neutron about faults in the data plane that are affecting the ports. A new REST API field is proposed to that end.

4.1. Problem Description

An initial description of the problem was introduced in bug #159801 [1]. This spec focuses on capturing one (main) part of the problem there described, i.e. extending Neutron’s REST API to cover the scenario of allowing external tools to report network failures to Neutron. Out of scope of this spec are works to enable port status changes to be received and managed by mechanism drivers.

This spec also tries to address bug #1575146 [2]. Specifically, and argued by the Neutron driver team in [3]:

  • Neutron should not shut down the port completly upon detection of physnet failure; connectivity between instances on the same node may still be reachable. Externals tools may or may not want to trigger a status change on the port based on their own logic and orchestration.
  • Port down is not detected when an uplink of a switch is down;
  • The physnet bridge may have multiple physical interfaces plugged; shutting down the logical port may not be needed in case network redundancy is in place.

4.2. Proposed Change

A couple of possible approaches were proposed in [1] (comment #3). This spec proposes tackling the problema via a new extension API to the port resource. The extension adds a new attribute ‘dp-down’ (data plane down) to represent the status of the data plane. The field should be read-only by tenants and read-write by admins.

Neutron should send out an event to the message bus upon toggling the data plane status value. The event is relevant for e.g. auditing.

4.2.1. Data Model Impact

A new attribute as extension will be added to the ‘ports’ table.

Attribute Name Type Access Default Value Validation/ Conversion Description
dp_down boolean RO, tenant RW, admin False True/False  

4.2.2. REST API Impact

A new API extension to the ports resource is going to be introduced.

    'ports': {
        'dp_down': {'allow_post': False, 'allow_put': True,
                    'default': False, 'convert_to': convert_to_boolean,
                    'is_visible': True},
} Examples

Updating port data plane status to down:

PUT /v2.0/ports/<port-uuid>
Accept: application/json
    "port": {
        "dp_down": true

4.2.3. Command Line Client Impact

neutron port-update [--dp-down <True/False>] <port>
openstack port set [--dp-down <True/False>] <port>

Argument –dp-down is optional. Defaults to False.

4.2.4. Security Impact


4.2.5. Notifications Impact

A notification (event) upon toggling the data plane status (i.e. ‘dp-down’ attribute) value should be sent to the message bus. Such events do not happen with high frequency and thus no negative impact on the notification bus is expected.

4.2.6. Performance Impact


4.2.7. IPv6 Impact


4.2.8. Other Deployer Impact


4.2.9. Developer Impact


4.3. Implementation

4.3.1. Assignee(s)

  • cgoncalves

4.3.2. Work Items

  • New ‘dp-down’ attribute in ‘ports’ database table
  • API extension to introduce new field to port
  • Client changes to allow for data plane status (i.e. ‘dp-down’ attribute’) being set
  • Policy (tenants read-only; admins read-write)

4.4. Documentation Impact

Documentation for both administrators and end users will have to be contemplated. Administrators will need to know how to set/unset the data plane status field.

4.5. References

[1]RFE: Port status update, https://bugs.launchpad.net/neutron/+bug/1598081
[2]RFE: ovs port status should the same as physnet https://bugs.launchpad.net/neutron/+bug/1575146
[3]Neutron Drivers meeting, July 21, 2016 http://eavesdrop.openstack.org/meetings/neutron_drivers/2016/neutron_drivers.2016-07-21-22.00.html