Instances with SR-IOV port is getting failed with port binding error message

Issue

• Why instance launch operations is getting failed with port binding failure message ?
• Why instance is getting despite of configured SRIOV agent on compute nodes ?
• Instance spawn operation using SR-IOV port is getting failed with following call trace in nova compute logs.

2016-12-07 11:51:12.298 5359 ERROR nova.compute.manager [req-2efac9a5-3d87-4552-a155-077639cd30f0 13469c01dc0e4abf8d6d5db37e374801 67ec9aab53dd46e6af5496b2876a739f - - -] [instance: 429312d0-eda5-484f-ab5e-7dec29c5ab28] Instance failed to spawn
2016-12-07 11:51:12.298 5359 ERROR nova.compute.manager [instance: 429312d0-eda5-484f-ab5e-7dec29c5ab28] Traceback (most recent call last):
2016-12-07 11:51:12.298 5359 ERROR nova.compute.manager [instance: 429312d0-eda5-484f-ab5e-7dec29c5ab28]   File "/usr/lib/python2.7/site-packages/nova/compute/manager.py", line 2180, in _build_resources
2016-12-07 11:51:12.298 5359 ERROR nova.compute.manager [instance: 429312d0-eda5-484f-ab5e-7dec29c5ab28]     yield resources
2016-12-07 11:51:12.298 5359 ERROR nova.compute.manager [instance: 429312d0-eda5-484f-ab5e-7dec29c5ab28]   File "/usr/lib/python2.7/site-packages/nova/compute/manager.py", line 2033, in _build_and_run_instance
2016-12-07 11:51:12.298 5359 ERROR nova.compute.manager [instance: 429312d0-eda5-484f-ab5e-7dec29c5ab28]     block_device_info=block_device_info)
2016-12-07 11:51:12.298 5359 ERROR nova.compute.manager [instance: 429312d0-eda5-484f-ab5e-7dec29c5ab28]   File "/usr/lib/python2.7/site-packages/nova/virt/libvirt/driver.py", line 2593, in spawn
2016-12-07 11:51:12.298 5359 ERROR nova.compute.manager [instance: 429312d0-eda5-484f-ab5e-7dec29c5ab28]     write_to_disk=True)
2016-12-07 11:51:12.298 5359 ERROR nova.compute.manager [instance: 429312d0-eda5-484f-ab5e-7dec29c5ab28]   File "/usr/lib/python2.7/site-packages/nova/virt/libvirt/driver.py", line 4528, in _get_guest_xml
2016-12-07 11:51:12.298 5359 ERROR nova.compute.manager [instance: 429312d0-eda5-484f-ab5e-7dec29c5ab28]     context)
2016-12-07 11:51:12.298 5359 ERROR nova.compute.manager [instance: 429312d0-eda5-484f-ab5e-7dec29c5ab28]   File "/usr/lib/python2.7/site-packages/nova/virt/libvirt/driver.py", line 4394, in _get_guest_config
2016-12-07 11:51:12.298 5359 ERROR nova.compute.manager [instance: 429312d0-eda5-484f-ab5e-7dec29c5ab28]     flavor, virt_type, self._host)
2016-12-07 11:51:12.298 5359 ERROR nova.compute.manager [instance: 429312d0-eda5-484f-ab5e-7dec29c5ab28]   File "/usr/lib/python2.7/site-packages/nova/virt/libvirt/vif.py", line 458, in get_config
2016-12-07 11:51:12.298 5359 ERROR nova.compute.manager [instance: 429312d0-eda5-484f-ab5e-7dec29c5ab28]     _("Unexpected vif_type=%s") % vif_type)
2016-12-07 11:51:12.298 5359 ERROR nova.compute.manager [instance: 429312d0-eda5-484f-ab5e-7dec29c5ab28] NovaException: Unexpected vif_type=binding_failed
2016-12-07 11:51:12.298 5359 ERROR nova.compute.manager [instance: 429312d0-eda5-484f-ab5e-7dec29c5ab28]