Update ROC to 1.4.50 for release-1.6

Change-Id: Ia4c792fb00716d5127c6133b1c3ed06b44d241fa
diff --git a/roc-4g-models-v4.json b/roc-4g-models-v4.json
index bcecf8e..7a80422 100644
--- a/roc-4g-models-v4.json
+++ b/roc-4g-models-v4.json
@@ -79,6 +79,7 @@
                 {
                     "admin-status": "ENABLE",
                     "display-name": "IP pool",
+                    "dnn": "internet",
                     "dns-primary": "8.8.8.8",
                     "id": "aiab-ip-pool",
                     "mtu": 1460,