update the network design to make support easier and cleaner

Change-Id: Iddf25266e3fd534ba88887acb7116faa04224c39
(cherry picked from commit c15f8e1231905cb83e0db014b8c1b3d7c72b23f0)
diff --git a/roles/compute-node/vars/main.yml b/roles/compute-node/vars/main.yml
index 64316c3..05425ea 100644
--- a/roles/compute-node/vars/main.yml
+++ b/roles/compute-node/vars/main.yml
@@ -3,9 +3,12 @@
 compute_node:
     interfaces:
         fabric: "{{ fabric_iface | default('fabric') }}"
-        management: "{{ management_iface | default('br-mgmt') }}"
+        management: "{{ management_iface | default('mgmtbr') }}"
         external: "{{ external_iface | default('') }}"
     addresses:
         fabric: "{{ fabric_ip | mandatory }}"
         management: "{{ management_ip | default('dhcp') }}"
         external: "{{ external_ip | default('manual') }}"
+    gateway:
+        external: "{{ external_gw | default('') }}"
+        management: "{{ management_gw | default('') }}"