I deployed a VTN Coordinator, a OpenDaylight Controller, and Mininet in my test environment.

I used the script (multitree.py) put in the following wiki page for Mininet.
https://wiki.opendaylight.org/view/OpenDaylight_Virtual_Tenant_Network_(VTN):Installation:VTN_Manager#Multiple_Clusters_of_Controllers

First, I executed the following curl command to register the controller to the VTN Coordinator.

curl -v -X POST -H 'content-type: application/json' -H 'username: admin' -H 'password: adminpass' -H 'ipaddr:127.0.0.1' -d '{"controller": {"controller_id": "odc1", "ipaddr":"192.168.60.180", "type": "odc", "version": "1.0", "auditstatus":"enable"}}' http://127.0.0.1:8080/vtn-webapi/controllers.json

Next, I executed curl command to list physical link information.
https://wiki.opendaylight.org/view/OpenDaylight_Virtual_Tenant_Network_(VTN):VTNCoordinator:RestApi:Physical_Link_Function

However, the response body for the curl command is empty.

1. curl -v -X GET -H 'content-type: application/json' -H 'username: admin' -H 'password: adminpass' http://127.0.0.1:8080/vtn-webapi/controllers/odc1/links.json

• About to connect() to 127.0.0.1 port 8080 (#0)
• Trying 127.0.0.1... connected
• Connected to 127.0.0.1 (127.0.0.1) port 8080 (#0)
  > GET /vtn-webapi/controllers/odc1/links.json HTTP/1.1
  > User-Agent: curl/7.19.7 (x86_64-redhat-linux-gnu) libcurl/7.19.7 NSS/3.12.9.0 zlib/1.2.3 libidn/1.18 libssh2/1.2.2
  > Host: 127.0.0.1:8080
  > Accept: /
  > content-type: application/json
  > username: admin
  > password: adminpass
  >
  < HTTP/1.1 200 OK
  < Server: Apache-Coyote/1.1
  < Content-Type: application/json;charset=UTF-8
  < Content-Length: 12
  < Date: Thu, 20 Feb 2014 04:48:50 GMT
  <
• Connection #0 to host 127.0.0.1 left intact
• Closing connection #0 {"links":[]}

After I registered the controller,
I saw the following ERROR messages in /usr/local/vtn/var/drvodcd/log/pfcd_message.log.

2014-02-20 13:46:30.651178: [1447]: ERROR: odcdriver: No corresponding port available . Error occured
2014-02-20 13:46:30.651212: [1447]: ERROR: odcdriver: Error return from fill config node_vector failure
2014-02-20 13:46:30.651222: [1447]: ERROR: odcdriver: Error occured while parsing
2014-02-20 13:46:30.651259: [1447]: ERROR: odcdriver: Error occured in getting link details
2014-02-20 13:47:10.734439: [1447]: ERROR: odcdriver: No corresponding port available . Error occured
2014-02-20 13:47:10.734489: [1447]: ERROR: odcdriver: Error return from fill config node_vector failure
2014-02-20 13:47:10.734500: [1447]: ERROR: odcdriver: Error occured while parsing
2014-02-20 13:47:10.734542: [1447]: ERROR: odcdriver: Error occured in getting link details
2014-02-20 13:47:50.833432: [1447]: ERROR: odcdriver: No corresponding port available . Error occured
2014-02-20 13:47:50.833477: [1447]: ERROR: odcdriver: Error return from fill config node_vector failure
2014-02-20 13:47:50.833503: [1447]: ERROR: odcdriver: Error occured while parsing
2014-02-20 13:47:50.833542: [1447]: ERROR: odcdriver: Error occured in getting link details

Information of my machine is as follows:

1. git log -3 --oneline
   a11652c Merge "Add Delay to FT after mininet session termination"
   5d40fd5 Add Delay to FT after mininet session termination
   25ef73d Fix VTN-2 to solve logical port computation in multiple controller scenarios

OS: RHEL 6.1