Debugging Netvirt/Networking-odl Port Status Update

Recent versions of Opendaylight Netvirt support dynamic update of Neutron port status via websocket and the networking-odl ML2 plugin knows how to take advantage of this feature. The following is a basic description of the internals of this feature followed by a guide for how to debug it.

How Port Status Update Works

When Neutron/networking-odl boots it registers a websocket based subscription to all neutron ports in the ODL operational yang model. Once this websocket subscription is connected, networking-odl receives json based notifications for every time Netvirt changes the status of a port. Note that for now this only happens at the time of port binding, if a port should go down, e.g., the VM crashes, Netvirt will not update the port status.

Note that a failure of port status update is not the only error that can cause a port to not transition to ACTIVE. Neutron uses a mechanism called provisioning-blocks to make sure two things happen before a port is transitioned to ACTIVE:

  • Port status update to ACTIVE

  • DHCP provisioning by the DHCP agent

If the DHCP provisioning does not succeed, e.g., if the dhcp agent is down, the port will not transition to active. In order to determine if DHCP provisioning worked look for either of the following two lines in the neutron logs:

Provisioning for port <uuid of port> completed by entity DHCP.

Provisioning complete for port <uuid of port> triggered by entity DHCP.

How to Debug Port Status


Neutron logs need to be set to debug. You can do this by having “debug = True” in your neutron.conf, generally under /etc/neutron.

The following ODL component log levels need to be set in <your karaf installation>/etc/org.ops4j.pax.logging.cfg:

log4j2.logger.npcl.level = TRACE =org.opendaylight.netvirt.neutronvpn.NeutronPortChangeListener = DEBUG =org.opendaylight.netvirt.neutronvpn.api.utils.NeutronUtils
log4j2.logger.oisah.level = INFO =org.opendaylight.genius.interfacemanager.renderer.ovs.statehelpers.OvsInterfaceStateAddHelper

2) Check that the websocket is connected

Websocket connection status is logged in the neutron logs. Check that this line is the last websocket status logged before your port was created:

websocket transition to status ODL_WEBSOCKET_CONNECTED

Note: The connection can disconnect but should reconnect so you can have multiple lines like this in the log with different statuses. You can now follow the transitions in this case.

If the websocket is not connected, either something is wrong with your deployment or ODL is not running. It may be worth checking if a firewall is blocking the websocket port which is 8185 by default but may be custom configured in a file called 10-rest-connector.xml under your karaf installation.

3) Check whether networking-odl received the port status update

All port status notifications are logged in the neutron logs like this:

Update port for port id <uuid of port> <ACTIVE|DOWN>

Note that for VM ports Netvirt will initially report that the port is DOWN until the basic flows are configured.

If there is no log line like this reporting your port is ACTIVE it is best to…

4) Check whether Netvirt transitioned the port to ACTIVE

Look for the following in karaf.log:

writePortStatus: operational port status for <uuid of port> set to <ACTIVE|DOWN>

Again, remember that for VM ports the port is initially reported as DOWN and soon after as ACTIVE.

If this log line is missing…

5) Check whether the Neutron port was received by Netvirt

Adding Port : key: <iid of the port, including uuid>, value=<dump of the port>

If this line is missing it means that something is wrong with the REST communication between networking-odl and ODL.

If this line is present but the line from (4) is not, it probably means that the southbound OpenFlow Port Status event was never received. Now…

6) Check whether the Genius operational port status was created

Check for this:

Adding Interface State to Oper DS for interface <tap interface name>

The tap interface name is the word “tap-” followed by the initial 7 characters of the neutron port’s UUID. If this line is missing, you have confirmed that the southbound port was never received via openflowplugin. This could mean that the switch is not connected or perhaps the VM never booted.

7) Something deeper is wrong

Although unlikely, if you will have made it this far and still have no answer, something much deeper is wrong and a more serious debugging effort is required.