experiments: use larger prefix for dist_memcache

For largescale experiment we otherwise run out of IPs

experiments/pyexps/dist_memcache.py

@@ -99,14 +99,16 @@ for host_type in host_types:
             m = int(n_host / 2)
             servers = sim.create_basic_hosts(e, m, 'server_%d' % (i,),
                     switch, sim.I40eNIC, host_class, node.I40eLinuxNode,
-                    node.MemcachedServer, ip_start = i * n_host + 1)
+                    node.MemcachedServer, ip_start = i * n_host + 1,
+                    ip_prefix=16)
             for s in servers:
                 e.assign_sim_host(s, h_i)
                 e.assign_sim_host(s.nics[0], h_i)
 
             clients = sim.create_basic_hosts(e, m, 'client_%d' % (i,),
                     switch, sim.I40eNIC, host_class, node.I40eLinuxNode,
-                    node.MemcachedClient, ip_start = i * n_host + 1 + m)
+                    node.MemcachedClient, ip_start = i * n_host + 1 + m,
+                    ip_prefix=16)
             for c in clients:
                 c.wait = True
                 e.assign_sim_host(c, h_i)