Comment 1 for bug 1411163

I see the issue, when dhcp port is first created and then the router port created on the new host.

In this case, when dhcp port is first created, it has to create tunnel port also. But it is not doing that -

When a dhcp server is moved new host,
1) network-hostagent binding is updated(properly i.e with new host).
2) dhcp port-hostagent binding is not updated( dhcp port is still bound to old host)
If dhcp port-bound agent is different from the new dhcp agent(which is now taking care of this dhcp port), neutron plugin won't notify the l2pop, and hence tunnel is not created.

def update_device_up(self, rpc_context, **kwargs):
        if (host and not plugin.port_bound_to_host(rpc_context,
                                                   port_id, host)):
            LOG.debug("Device %(device)s not bound to the"
                      " agent host %(host)s",
                      {'device': device, 'host': host})
            return

So, the root cause is - issue with dhcp and not l2pop(l2pop conditions are fine).