create /var/run/netns if it's not there

start_testbed.py

@@ -154,6 +154,9 @@ def start_node(base_name,i):
     # Add the node's info to our list.
     nodelist.append(entry)
 
+# First, make sure that /var/run/netns exists.
+subprocess.call([ 'sudo', 'mkdir', '-p', '/var/run/netns' ])
+
 for n in range(ntwk['num_nodes']):
     start_node(ntwk['name'],n)