As Luis said, VTN Manager system tests failed to send packets on Mininet.
https://lists.opendaylight.org/pipermail/vtn-dev/2014-September/000608.html

The issue does not occur on OpenFlow 1.3 switches, but occurs on OpenFlow 1.0 switches.

[How to reproduce this issue]

1. Go into the Karaf distribution (RC1) directory.

2. Clean up environment.
$ pwd
/home/hideyuki/tmp/distribution-karaf-0.2.0-Helium-RC1
$ rm -rf data/
$ rm -rf configuration/startup/default/vtn/

3. Run the Karaf.
$ ./bin/karaf

4. Install the following three features on the Karaf console.
feature:install odl-vtn-manager-all
feature:install odl-adsal-compatibility-all
feature:install odl-openflowplugin-all

5. Create a vBridge.
PFA. I attached the script which I used to create the vBridge.

6. Run Mininet in OpenFlow 1.0.
> sudo mn --controller remote,192.168.2.56

7. Ping!
> h1 ping h2
PING 10.0.0.2 (10.0.0.2) 56(84) bytes of data.
From 10.0.0.1 icmp_seq=1 Destination Host Unreachable From 10.0.0.1 icmp_seq=2 Destination Host Unreachable From 10.0.0.1 icmp_seq=3 Destination Host Unreachable

At that point, I saw the following WARN message output by VTN Manager.

addPort: Property has been changed: port=OF|1@OF|00:00:00:00:00:00:00:01, prop=PortProperty[name=s1-eth1,cost=1000,enabled] -> PortProperty[name=s1-eth1,cost=1000,disabled]

vBridge:vtn1.vbr1: Drop packet because outgoing port is down: src=86:47:c2:46:1e:a2, dst=f2:0e:a3:a7:16:ef, port=OF|1@OF|00:00:00:00:00:00:00:01, type=0x806, vlan=0

VTN Manager dropped packets, because the outgoing port id down.

However, if I restart Mininet, the issue is removed.

8. Stop, and Re-Start Mininet.

9. Ping again!
> h1 ping h2
PING 10.0.0.2 (10.0.0.2) 56(84) bytes of data.
64 bytes from 10.0.0.2: icmp_seq=1 ttl=64 time=250 ms
64 bytes from 10.0.0.2: icmp_seq=2 ttl=64 time=0.185 ms
64 bytes from 10.0.0.2: icmp_seq=3 ttl=64 time=0.053 ms