Contrail 3.0.2X : Service instance inactive if all interfaces in porttuple are sub interfaces

[Himanshu]

The issue is seen in Contrail 3.0.2X version.

Issue : When spawning a V2 service instance that has all interfaces under port tuples associated with sub-interfaces, the SI fails to get spawned. The issue is fixed in 3.1X Contrail release onwards. I have tested this too in lab.

To replicate the issue:
Contrail 3.0.2.X and vSRX 15.1X49.D40
- Create 6 Virtual Networks in Contrail
- Create a vSRX VM in Openstack with 3 interfaces associated with the first three Virtual networks.
- Create 3 sub-interfaces in Contrail under Configure - Networking - Ports associated to the 3 vSRX ports.
- Create a two V2 Service instance template one with 2 interfaces and other with 3 interfaces
- Spawn a Service instance first with the SI template with 2 interfaces and then with the other SI template with 3 interfaces. Select the appropriate sub interfaces under port tuple section.
- In both cases the SI will be stuck in spawning state forever. It might eventually timeout and become inactive.
- Another observation is that if any of three interfaces under port tuple definition (in Service instance settings) is not a sub-interface, the SI comes up just fine.

The issue is fixed in Contrail 3.1.X release and above. However, I was not able to find any Launchpad bugs for this issue hence reporting this issue.