Add options for auto MAC and ARP setup.

Auto MAC setup sets each host MAC equal to its DPID, which simplifies
debugging.

Auto ARP setup removes the need for broadcast support for ARP, which
enables a smaller NOX controller.

mininet/node.py

@@ -6,7 +6,7 @@ import os, signal, sys, select
 flush = sys.stdout.flush
 
 from mininet.logging_mod import lg
-from mininet.util import quietRun
+from mininet.util import quietRun, macColonHex, ipStr
 
 class Node(object):
     '''A virtual network node is simply a shell in a network namespace.
@@ -160,6 +160,28 @@ class Node(object):
         self.intfs += [intfName]
         return intfName
 
+    def setMAC(self, intf, mac):
+        '''Set the MAC address for an interface.
+
+        @param mac MAC address as unsigned int
+        '''
+        mac_str = macColonHex(mac)
+        result = self.cmd(['ifconfig', intf, 'down'])
+        result += self.cmd(['ifconfig', intf, 'hw', 'ether', mac_str])
+        result += self.cmd(['ifconfig', intf, 'up'])
+        return result
+
+    def setARP(self, ip, mac):
+        '''Add an ARP entry.
+
+        @param ip IP address as unsigned int
+        @param mac MAC address as unsigned int
+        '''
+        ip_str = ipStr(ip)
+        mac_str = macColonHex(mac)
+        result = self.cmd(['arp', '-s', ip_str, mac_str])
+        return result
+
     def setIP(self, intf, ip, bits):
         '''Set the IP address for an interface.