diff --git a/mininet/net.py b/mininet/net.py
index d082b00d2ee7ece2339acc2045a9a275fceec3a1..4834dff807454ac92457bfd8f7e7511c3b074393 100755
--- a/mininet/net.py
+++ b/mininet/net.py
@@ -312,8 +312,8 @@ def addLink( self, node1, node2, port1=None, port2=None,
             port1: source port
             port2: dest port
             returns: link object"""
-        mac1 = macColonHex( random.randint( 1, (2**24 - 1) ) )
-        mac2 = macColonHex( random.randint( 1, (2**24 - 1) ) )
+        mac1 = macColonHex( random.randint(1, 2**48 - 1) & 0xfeffffffffff  | 0x020000000000 )
+        mac2 = macColonHex( random.randint(1, 2**48 - 1) & 0xfeffffffffff  | 0x020000000000 )
         defaults = { 'port1': port1,
                      'port2': port2,
                      'addr1': mac1,