ndn: bug fixes in nfdc and experiments

Change-Id: I8cb9b0a9e53e0319e3f18ab6a52867d406a31fd5
diff --git a/ndn/experiments/failure_experiment.py b/ndn/experiments/failure_experiment.py
index b25cbfe..a27b0a6 100644
--- a/ndn/experiments/failure_experiment.py
+++ b/ndn/experiments/failure_experiment.py
@@ -23,6 +23,7 @@
 
 from ndn.experiments.experiment import Experiment
 from ndn.nlsr import Nlsr
+from ndn.apps.ndn_ping_client import NDNPingClient
 
 import time
 
@@ -57,7 +58,7 @@
 
                 for other in self.net.hosts:
                     if host.name != other.name:
-                        self.ping(host, other, self.PING_COLLECTION_TIME_AFTER_RECOVERY)
+                        NDNPingClient.ping(host, other, self.PING_COLLECTION_TIME_AFTER_RECOVERY)
 
         # Collect pings for more seconds after CSU is up
         time.sleep(self.PING_COLLECTION_TIME_AFTER_RECOVERY)
diff --git a/ndn/experiments/mcn_failure_experiment.py b/ndn/experiments/mcn_failure_experiment.py
index 019c214..62bdcab 100644
--- a/ndn/experiments/mcn_failure_experiment.py
+++ b/ndn/experiments/mcn_failure_experiment.py
@@ -22,6 +22,7 @@
 # If not, see <http://www.gnu.org/licenses/>.
 
 from ndn.experiments.experiment import Experiment
+from ndn.apps.ndn_ping_client import NDNPingClient
 
 import time
 
@@ -58,7 +59,7 @@
 
         # Restart pings
         for nodeToPing in self.pingedDict[mostConnectedNode]:
-            self.ping(mostConnectedNode, nodeToPing, self.PING_COLLECTION_TIME_AFTER_RECOVERY)
+            NDNPingClient.ping(mostConnectedNode, nodeToPing, self.PING_COLLECTION_TIME_AFTER_RECOVERY)
 
         # Collect pings for more seconds after MCN is up
         time.sleep(self.PING_COLLECTION_TIME_AFTER_RECOVERY)
diff --git a/ndn/experiments/multiple_failure_experiment.py b/ndn/experiments/multiple_failure_experiment.py
index 0836949..6b4ce6b 100644
--- a/ndn/experiments/multiple_failure_experiment.py
+++ b/ndn/experiments/multiple_failure_experiment.py
@@ -23,6 +23,7 @@
 
 from ndn.experiments.experiment import Experiment
 from ndn.nlsr import Nlsr
+from ndn.apps.ndn_ping_client import NDNPingClient
 
 import time
 
@@ -74,7 +75,7 @@
 
             # Restart pings
             for nodeToPing in self.pingedDict[host]:
-                self.ping(host, nodeToPing, nPings)
+                NDNPingClient.ping(host, nodeToPing, nPings)
 
             time.sleep(self.RECOVERY_INTERVAL - recovery_time)