The test case for verifying the vxlan tunneling feature without using any
ingress tunnel traffic. The virtual switch(OVS) is configured to mangle and
generate tunnel traffic in the deployment. The packet flow in the test case is
as follows

TRAFFIC-IN --> [ENCAP-PKT] --> [MOD-PKT] --> [DECAP-PKT] --> TRAFFIC-OUT

ENCAP-PKT - Encapsulate the ingress packet to a tunnel type.
MOD-PKT - Modify the tunnel header to match the following decap interface.
DECAP-PKT - Decapsulate the newly generated tunneled packet.

Change-Id: Ie24bacb3cb1c069bd60403e5a4ef8bcdf0e12e54