[CORD-2270]
Support head node on Ubuntu 16.04 (Xenial)

Change-Id: Ic13ea784b8fa55a481f08d21f5187fd37d13499c
diff --git a/roles/dhcpd/defaults/main.yml b/roles/dhcpd/defaults/main.yml
index 66edc52..9772910 100644
--- a/roles/dhcpd/defaults/main.yml
+++ b/roles/dhcpd/defaults/main.yml
@@ -1,4 +1,4 @@
-
+---
 # Copyright 2017-present Open Networking Foundation
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
@@ -13,18 +13,17 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-
----
 # dhcpd/defaults/main.yml
 
-# http://serverfault.com/questions/40712/what-range-of-mac-addresses-can-i-safely-use-for-my-virtual-machines
-hwaddr_prefix: "c2a4"
-
 site_name: placeholder-sitename
 site_suffix: "{{ site_name }}.test"
 
-# Management IP range from DHCP settings
-mgmt_ipv4_first_octets: "192.168.200"
+management_net_cidr: "192.168.200.0/24"
+
+vtn_net_management_host_cidr: "{{ management_net_cidr }}"
+
+# http://serverfault.com/questions/40712/what-range-of-mac-addresses-can-i-safely-use-for-my-virtual-machines
+vtn_net_management_host_hwaddr_prefix: "06A6"
 
 # node lists
 head_lxd_list: []
@@ -33,13 +32,10 @@
 dns_search:
   - "{{ site_suffix }}"
 
-dns_servers:
-  - "{{ mgmt_ipv4_first_octets }}.1"
-
 dhcpd_subnets:
-  - interface: mgmtbr
-    cidr: "{{ mgmt_ipv4_first_octets }}.1/24"
-    dhcp_first: 129
+  - interface: mgmtbridge
+    cidr: "{{ management_net_cidr }}"
+    dhcp_first: 193
     dhcp_last: 254
     other_static:
       - physical_node_list