diff --git a/client/tests/kvm/kvm_utils.py b/client/tests/kvm/kvm_utils.py
index fb2d1c2..7c0946e 100644
--- a/client/tests/kvm/kvm_utils.py
+++ b/client/tests/kvm/kvm_utils.py
@@ -5,6 +5,7 @@ KVM test utility functions.
 """
 
 import time, string, random, socket, os, signal, re, logging, commands, cPickle
+import fcntl, shelve
 from autotest_lib.client.bin import utils
 from autotest_lib.client.common_lib import error, logging_config
 import kvm_subprocess
@@ -82,6 +83,104 @@ def get_sub_dict_names(dict, keyword):
 
 # Functions related to MAC/IP addresses
 
+def get_mac_from_pool(root_dir, vm, nic_index, prefix='00:11:22:33:'):
+    """
+    random generated mac address.
+
+    1) First try to generate macaddress based on the mac address prefix.
+    2) And then try to use total random generated mac address.
+
+    @param root_dir: Root dir for kvm
+    @param vm: Here we use instance of vm
+    @param nic_index: The index of nic.
+    @param prefix: Prefix of mac address.
+    @Return: Return mac address.
+    """
+
+    lock_filename = os.path.join(root_dir, "mac_lock")
+    lock_file = open(lock_filename, 'w')
+    fcntl.lockf(lock_file.fileno() ,fcntl.LOCK_EX)
+    mac_filename = os.path.join(root_dir, "address_pool")
+    mac_shelve = shelve.open(mac_filename, writeback=False)
+
+    mac_pool = mac_shelve.get("macpool")
+
+    if not mac_pool:
+        mac_pool = {}
+    found = False
+
+    val = "%s:%s" % (vm, nic_index)
+    for key in mac_pool.keys():
+        if val in mac_pool[key]:
+            mac_pool[key].append(val)
+            found = True
+            mac = key
+
+    while not found:
+        postfix = "%02x:%02x" % (random.randint(0x00,0xfe),
+                                random.randint(0x00,0xfe))
+        mac = prefix + postfix
+        mac_list = mac.split(":")
+        # Clear multicast bit
+        mac_list[0] = int(mac_list[0],16) & 0xfe
+        # Set local assignment bit (IEEE802)
+        mac_list[0] = mac_list[0] | 0x02
+        mac_list[0] = "%02x" % mac_list[0]
+        mac = ":".join(mac_list)
+        if mac not in mac_pool.keys() or 0 == len(mac_pool[mac]):
+            mac_pool[mac] = ["%s:%s" % (vm,nic_index)]
+            found = True
+    mac_shelve["macpool"] = mac_pool
+    logging.debug("generating mac addr %s " % mac)
+
+    mac_shelve.close()
+    fcntl.lockf(lock_file.fileno(), fcntl.LOCK_UN)
+    lock_file.close()
+    return mac
+
+
+def put_mac_to_pool(root_dir, mac, vm):
+    """
+    Put the macaddress back to address pool
+
+    @param root_dir: Root dir for kvm
+    @param vm: Here we use instance attribute of vm
+    @param mac: mac address will be put.
+    @Return: mac address.
+    """
+
+    lock_filename = os.path.join(root_dir, "mac_lock")
+    lock_file = open(lock_filename, 'w')
+    fcntl.lockf(lock_file.fileno() ,fcntl.LOCK_EX)
+    mac_filename = os.path.join(root_dir, "address_pool")
+    mac_shelve = shelve.open(mac_filename, writeback=False)
+
+    mac_pool = mac_shelve.get("macpool")
+
+    if not mac_pool or (not mac in mac_pool):
+        logging.debug("Try to free a macaddress does no in pool")
+        logging.debug("macaddress is %s" % mac)
+        logging.debug("pool is %s" % mac_pool)
+    else:
+        if len(mac_pool[mac]) <= 1:
+            mac_pool.pop(mac)
+        else:
+            for value in mac_pool[mac]:
+                if vm in value:
+                    mac_pool[mac].remove(value)
+                    break
+            if len(mac_pool[mac]) == 0:
+                mac_pool.pop(mac)
+
+    mac_shelve["macpool"] = mac_pool
+    logging.debug("freeing mac addr %s " % mac)
+
+    mac_shelve.close()
+    fcntl.lockf(lock_file.fileno(), fcntl.LOCK_UN)
+    lock_file.close()
+    return mac
+
+
 def mac_str_to_int(addr):
     """
     Convert MAC address string to integer.
diff --git a/client/tests/kvm/kvm_vm.py b/client/tests/kvm/kvm_vm.py
index 6cd0688..a9ba6e7 100755
--- a/client/tests/kvm/kvm_vm.py
+++ b/client/tests/kvm/kvm_vm.py
@@ -5,7 +5,7 @@ Utility classes and functions to handle Virtual Machine creation using qemu.
 @copyright: 2008-2009 Red Hat Inc.
 """
 
-import time, socket, os, logging, fcntl, re, commands, glob
+import time, socket, os, logging, fcntl, re, commands, shelve, glob
 import kvm_utils, kvm_subprocess, kvm_monitor, rss_file_transfer
 from autotest_lib.client.common_lib import error
 from autotest_lib.client.bin import utils
@@ -117,6 +117,7 @@ class VM:
         self.params = params
         self.root_dir = root_dir
         self.address_cache = address_cache
+        self.mac_prefix = params.get('mac_prefix')
         self.netdev_id = []
 
         # Find a unique identifier for this VM
@@ -126,8 +127,15 @@ class VM:
             if not glob.glob("/tmp/*%s" % self.instance):
                 break
 
+        if self.mac_prefix is None:
+            s, o = commands.getstatusoutput("ifconfig eth0")
+            if s == 0:
+                mac = re.findall("HWaddr (\S*)", o)[0]
+                self.mac_prefix = '00' + mac[8:] + ':'
+
 
-    def clone(self, name=None, params=None, root_dir=None, address_cache=None):
+    def clone(self, name=None, params=None, root_dir=None,
+                    address_cache=None, mac_clone=True):
         """
         Return a clone of the VM object with optionally modified parameters.
         The clone is initially not alive and needs to be started using create().
@@ -138,6 +146,7 @@ class VM:
         @param params: Optional new VM creation parameters
         @param root_dir: Optional new base directory for relative filenames
         @param address_cache: A dict that maps MAC addresses to IP addresses
+        @param mac_clone: Clone mac address or not.
         """
         if name is None:
             name = self.name
@@ -147,9 +156,19 @@ class VM:
             root_dir = self.root_dir
         if address_cache is None:
             address_cache = self.address_cache
-        return VM(name, params, root_dir, address_cache)
+        vm = VM(name, params, root_dir, address_cache)
+        if mac_clone:
+            # Clone mac address by coping 'self.instance' to the new vm.
+            vm.instance = self.instance
+        return vm
 
 
+    def free_mac_address(self):
+        nic_num = len(kvm_utils.get_sub_dict_names(self.params, "nics"))
+        for nic in range(nic_num):
+            mac = self.get_macaddr(nic_index=nic)
+            kvm_utils.put_mac_to_pool(self.root_dir, mac, vm=self.instance)
+
     def make_qemu_command(self, name=None, params=None, root_dir=None):
         """
         Generate a qemu command line. All parameters are optional. If a
@@ -383,6 +402,13 @@ class VM:
             mac = None
             if "address_index" in nic_params:
                 mac = kvm_utils.get_mac_ip_pair_from_dict(nic_params)[0]
+                self.set_mac_address(mac=mac, nic_index=vlan)
+            else:
+                mac = kvm_utils.get_mac_from_pool(self.root_dir,
+                                                  vm=self.instance,
+                                                  nic_index=vlan,
+                                                  prefix=self.mac_prefix)
+
             qemu_cmd += add_nic(help, vlan, nic_params.get("nic_model"), mac,
                                 self.netdev_id[vlan])
             # Handle the '-net tap' or '-net user' part
@@ -396,7 +422,7 @@ class VM:
             if tftp:
                 tftp = kvm_utils.get_path(root_dir, tftp)
             qemu_cmd += add_net(help, vlan, nic_params.get("nic_mode", "user"),
-                                nic_params.get("nic_ifname"),
+                                self.get_ifname(vlan),
                                 script, downscript, tftp,
                                 nic_params.get("bootp"), redirs,
                                 self.netdev_id[vlan])
@@ -720,7 +746,7 @@ class VM:
             lockfile.close()
 
 
-    def destroy(self, gracefully=True):
+    def destroy(self, gracefully=True, free_macaddr=True):
         """
         Destroy the VM.
 
@@ -731,6 +757,7 @@ class VM:
         @param gracefully: Whether an attempt will be made to end the VM
                 using a shell command before trying to end the qemu process
                 with a 'quit' or a kill signal.
+        @param free_macaddr: Whether free macaddresses when destory a vm.
         """
         try:
             # Is it already dead?
@@ -751,11 +778,18 @@ class VM:
                         logging.debug("Shutdown command sent; waiting for VM "
                                       "to go down...")
                         if kvm_utils.wait_for(self.is_dead, 60, 1, 1):
-                            logging.debug("VM is down")
+                            logging.debug("VM is down, free mac address.")
+                            # free mac address
+                            if free_macaddr:
+                                self.free_mac_address()
                             return
                     finally:
                         session.close()
 
+            # free mac address
+            if free_macaddr:
+                self.free_mac_address()
+
             if self.monitor:
                 # Try to destroy with a monitor command
                 logging.debug("Trying to kill VM with monitor command...")
@@ -881,10 +915,14 @@ class VM:
         nic_name = nics[index]
         nic_params = kvm_utils.get_sub_dict(self.params, nic_name)
         if nic_params.get("nic_mode") == "tap":
-            mac, ip = kvm_utils.get_mac_ip_pair_from_dict(nic_params)
+            mac = self.get_macaddr(index)
             if not mac:
                 logging.debug("MAC address unavailable")
                 return None
+            else:
+                mac = mac.lower()
+            ip = None
+
             if not ip or nic_params.get("always_use_tcpdump") == "yes":
                 # Get the IP address from the cache
                 ip = self.address_cache.get(mac)
@@ -897,6 +935,7 @@ class VM:
                              for nic in nics]
                 macs = [kvm_utils.get_mac_ip_pair_from_dict(dict)[0]
                         for dict in nic_dicts]
+                macs.append(mac)
                 if not kvm_utils.verify_ip_address_ownership(ip, macs):
                     logging.debug("Could not verify MAC-IP address mapping: "
                                   "%s ---> %s" % (mac, ip))
@@ -925,6 +964,71 @@ class VM:
                              "redirected" % port)
             return self.redirs.get(port)
 
+    def get_ifname(self, nic_index=0):
+        """
+        Return the ifname of tap device for the guest nic.
+
+        @param nic_index: Index of the NIC
+        """
+
+        nics = kvm_utils.get_sub_dict_names(self.params, "nics")
+        nic_name = nics[nic_index]
+        nic_params = kvm_utils.get_sub_dict(self.params, nic_name)
+        if nic_params.get("nic_ifname"):
+            return nic_params.get("nic_ifname")
+        else:
+            return "%s_%s_%s" % (nic_params.get("nic_model"),
+                                 nic_index, self.vnc_port)
+
+    def get_macaddr(self, nic_index=0):
+        """
+        Return the macaddr of guest nic.
+
+        @param nic_index: Index of the NIC
+        """
+        mac_filename = os.path.join(self.root_dir, "address_pool")
+        mac_shelve = shelve.open(mac_filename, writeback=False)
+        mac_pool = mac_shelve.get("macpool")
+        val = "%s:%s" % (self.instance, nic_index)
+        for key in mac_pool.keys():
+            if val in mac_pool[key]:
+                return key
+        return None
+
+    def set_mac_address(self, mac, nic_index=0, shareable=False):
+        """
+        Set mac address for guest. Note: It just update address pool.
+
+        @param mac: address will set to guest
+        @param nic_index: Index of the NIC
+        @param shareable: Where VM can share mac with other VM or not.
+        """
+        lock_filename = os.path.join(self.root_dir, "mac_lock")
+        lock_file = open(lock_filename, 'w')
+        fcntl.lockf(lock_file.fileno() ,fcntl.LOCK_EX)
+        mac_filename = os.path.join(self.root_dir, "address_pool")
+        mac_shelve = shelve.open(mac_filename, writeback=False)
+        mac_pool = mac_shelve.get("macpool")
+        if not mac_pool:
+            mac_pool = {}
+        value = "%s:%s" % (self.instance, nic_index)
+        if mac not in mac_pool.keys():
+            for key in mac_pool.keys():
+                if value in mac_pool[key]:
+                    mac_pool[key].remove(value)
+                if len(mac_pool[key]) == 0:
+                    mac_pool.pop(key)
+            mac_pool[mac] = [value]
+        else:
+            if shareable:
+                mac_pool[mac].append(value)
+            else:
+                logging.error("Mac address already be used!")
+                return False
+        mac_shelve["macpool"] = mac_pool
+        mac_shelve.close()
+        fcntl.lockf(lock_file.fileno(), fcntl.LOCK_UN)
+        lock_file.close()
 
     def get_pid(self):
         """
diff --git a/client/tests/kvm/tests_base.cfg.sample b/client/tests/kvm/tests_base.cfg.sample
index fd9e72f..6710c00 100644
--- a/client/tests/kvm/tests_base.cfg.sample
+++ b/client/tests/kvm/tests_base.cfg.sample
@@ -51,7 +51,7 @@ guest_port_remote_shell = 22
 nic_mode = user
 #nic_mode = tap
 nic_script = scripts/qemu-ifup
-address_index = 0
+#address_index = 0
 run_tcpdump = yes
 
 # Misc
