[openstack-dev] [L2-Gateway] connecting to hardware vtep not working

Jason Guy jguy at cumulusnetworks.com
Mon Mar 14 21:07:18 UTC 2016

I have the l2gateway stable/liberty release loaded in my openstack setup,
and can create the l2gateway, however the l2gateway-connection fails. I
have read doc which appears to be more up-to-date than the readme:

Assuming this image
is accurate, it looks like the neutron agent AND compute node connect to
the remote switch (hardware VTEP) using VXLAN. The neutron agent also
connects to the OVSDB-server on the remote switch. Obviously the VXLAN
tunnel is the data-plane, and the OVSDB-server connection is the

1) l2gateway-create - Creating an abstraction of an L2 gateway (hardware
VTEP) with its interface(s). It is not clear to me what to specify when
setting up the l2gateway.

neutron l2-gateway-create mlagsw \
--device name=sw11,interface_names="baremetal1" \
--device name=sw12,interface_names="baremetal1"

- Is the --device name correlate to one of the ovsdb_hosts, specified in
the l2gateway_agent.ini?
- Is the name meant to be resolveable via DNS? I would assume no, if it
gleans the IP from the .ini file.
- What does the "interface" parameter specify? Is this the interface the
remote VTEP will bind to the VXLAN bridge on the hardware VTEP?

2) l2gateway-connection-create - Binding a logical gateway to an overlay
network. This keeps failing for me, and I am not quite sure why. My neutron
net is called vmnet201.

root at linux: ~# neutron l2-gateway-connection-create mlagsw vmnet201
L2 Gateway Device sw11 could not be found.

- I assume this attempts to create the VXLAN tunnel to the remote VTEP(s).
Does it attempt the second device if the first fails? I only see one
failure message.
- Does the l2gateway-agent run the ovsdb-client?
- Does neutron need to run openvswitch, or can the ovsdb client use the
linuxbridge agent?

3) OVSDB-server connection:

- Should I see the connection to the ovsdb-server prior to executing the
- How would I see if the connection is up or not on the network node?
- Does this come up automatically when the l2gateway_agent is started after
reading the .ini file?
Should something show up in the log if it cannot create the connection? I
have debug=true, and do not see that the ovsdb connection is up or failing
to connect.

Any help would be greatly appreciated.

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