diff --git a/tripleo_common/actions/templates.py b/tripleo_common/actions/templates.py
index 0a64eeea6..a2ec4852b 100644
--- a/tripleo_common/actions/templates.py
+++ b/tripleo_common/actions/templates.py
@@ -182,6 +182,10 @@ class ProcessTemplatesAction(base.TripleOAction):
             # Allow no networks defined in network_data
             if network_data is None:
                 network_data = []
+            # Set internal network index key for each network, network
+            # resources are created with a tag tripleo_net_idx
+            for idx, _ in enumerate(network_data):
+                network_data[idx].update({'idx': idx})
         except swiftexceptions.ClientException:
             # Until t-h-t contains network_data.yaml we tolerate a missing file
             LOG.warning("No %s file found, ignoring"