diff --git a/src/communication.py b/src/communication.py
index 07ff4b8..046d14c 100644
--- a/src/communication.py
+++ b/src/communication.py
@@ -112,6 +112,12 @@ class ClusterCommunicationModule():
         elif command == '[START_LISTEN_TASK]':
             self.client_sock.send('[START_LISTEN_TASK_CHECK]  {}'.encode())
             print("The master has started listening for new task from Sepolia testnet...")
+        elif command == '[RUN_CONTAINER]':
+            image = json.loads(args)['image']
+            print(f"[RUN_CONTAINER] {image}")
+            time.sleep(3)
+
+            self.client_sock.send('[RUN_CONTAINER_SUCCESS]  {}'.encode())
 
         return True
 
@@ -181,36 +187,45 @@ class ClusterCommunicationModule():
 
     def run_container(self, image_name):
         def master_run(image_name):
-            print("Master run")
+            print("[Master] run")
             for i in range(5):
                 print(i)
                 time.sleep(1)
-            print("Master finished")
+            print("[Master] finished")
 
         def send_and_wait(conn_index, conn, image_name):
-            print(f"Worker {conn_index} run")
-            for i in range(7):
-                print(f"[WORKER {conn_index}] {i}")
-                time.sleep(1)
-            print(f"Worker {conn_index} finished")
+            try:
+                # build command
+                data = {'image': image_name}
+                command = '[RUN_CONTAINER]  {}'.format(json.dumps(data))
+
+                # send
+                conn.send(command.encode())
+                print(f"[WORKER {conn_index}] Send command {command}")
+
+                # wait
+                data, args = conn.recv(1024).decode().split('  ')
+                print(f"[WORKER {conn_index}] finished")
+
+            except:
+                print("[WARN] connection {conn_index} disconnected.")
             
+        # build threads
         threads = []
         master_t = threading.Thread(target=master_run, args=(image_name, ))
         threads.append(master_t)
 
         for index, conn in enumerate(self.worker_conns):
-            data = {'image': image_name}
-            command = '[RUN_CONTAINER]  {}'.format(json.dumps(data))
-            print(command)
-
             t = threading.Thread(target=send_and_wait, args=(index, conn, image_name))
             threads.append(t)
 
+        # start threads & wait
         for thread in threads:
             thread.start()
         for thread in threads:
             thread.join()
 
+        # all finished
         print("[INFO] All workers finished.")