use different images for cfg and other nodes
diff --git a/tcp_tests/templates/tcpcloud-default.yaml b/tcp_tests/templates/tcpcloud-default.yaml
index 2523790..32b5d8a 100644
--- a/tcp_tests/templates/tcpcloud-default.yaml
+++ b/tcp_tests/templates/tcpcloud-default.yaml
@@ -55,14 +55,16 @@
           private:
             address_pool: private-pool01
             dhcp: true
-            forward:
-              mode: nat
 
         group_volumes:
-         - name: cloudimage    # This name is used for 'backing_store' option for node volumes.
-           source_image: !os_env IMAGE_PATH  # https://cloud-images.ubuntu.com/trusty/current/trusty-server-cloudimg-amd64-disk1.img or
+         - name: cloudimage1404    # This name is used for 'backing_store' option for node volumes.
+           source_image: !os_env IMAGE_PATH1404  # https://cloud-images.ubuntu.com/trusty/current/trusty-server-cloudimg-amd64-disk1.img or
                                              # http://apt.tcpcloud.eu/images/ubuntu-14-04-x64-201608231134.qcow2
            format: qcow2
+         - name: cloudimage1604    # This name is used for 'backing_store' option for node volumes.
+           source_image: !os_env IMAGE_PATH1604  # https://cloud-images.ubuntu.com/xenial/current/xenial-server-cloudimg-amd64-disk1.img or
+                                             # http://apt.tcpcloud.eu/images/ubuntu-16-04-x64-201608231004.qcow2
+           format: qcow2
 
         nodes:
           - name: cfg01.mk22-lab-advanced.local
@@ -77,7 +79,7 @@
               volumes:
                 - name: system
                   capacity: !os_env NODE_VOLUME_SIZE, 150
-                  backing_store: cloudimage
+                  backing_store: cloudimage1604
                   format: qcow2
                 - name: iso  # Volume with name 'iso' will be used
                              # for store image with cloud-init metadata.
@@ -115,7 +117,7 @@
               volumes:
                 - name: system
                   capacity: !os_env NODE_VOLUME_SIZE, 150
-                  backing_store: cloudimage
+                  backing_store: cloudimage1404
                   format: qcow2
                 - name: iso  # Volume with name 'iso' will be used
                              # for store image with cloud-init metadata.
@@ -153,7 +155,7 @@
               volumes:
                 - name: system
                   capacity: !os_env NODE_VOLUME_SIZE, 150
-                  backing_store: cloudimage
+                  backing_store: cloudimage1404
                   format: qcow2
                 - name: iso  # Volume with name 'iso' will be used
                              # for store image with cloud-init metadata.
@@ -191,7 +193,7 @@
               volumes:
                 - name: system
                   capacity: !os_env NODE_VOLUME_SIZE, 150
-                  backing_store: cloudimage
+                  backing_store: cloudimage1404
                   format: qcow2
                 - name: iso  # Volume with name 'iso' will be used
                              # for store image with cloud-init metadata.
@@ -229,7 +231,7 @@
               volumes:
                 - name: system
                   capacity: !os_env NODE_VOLUME_SIZE, 150
-                  backing_store: cloudimage
+                  backing_store: cloudimage1404
                   format: qcow2
                 - name: iso  # Volume with name 'iso' will be used
                              # for store image with cloud-init metadata.
@@ -267,7 +269,7 @@
               volumes:
                 - name: system
                   capacity: !os_env NODE_VOLUME_SIZE, 150
-                  backing_store: cloudimage
+                  backing_store: cloudimage1404
                   format: qcow2
                 - name: iso  # Volume with name 'iso' will be used
                              # for store image with cloud-init metadata.
@@ -305,7 +307,7 @@
               volumes:
                 - name: system
                   capacity: !os_env NODE_VOLUME_SIZE, 150
-                  backing_store: cloudimage
+                  backing_store: cloudimage1404
                   format: qcow2
                 - name: iso  # Volume with name 'iso' will be used
                              # for store image with cloud-init metadata.
@@ -343,7 +345,7 @@
               volumes:
                 - name: system
                   capacity: !os_env NODE_VOLUME_SIZE, 150
-                  backing_store: cloudimage
+                  backing_store: cloudimage1404
                   format: qcow2
                 - name: iso  # Volume with name 'iso' will be used
                              # for store image with cloud-init metadata.