Return error if hns network exists for transparent network

network/network_windows.go

@@ -378,13 +378,19 @@ func (nm *networkManager) newNetworkImplHnsV2(nwInfo *EndpointInfo, extIf *exter
 			if err != nil {
 				return nil, fmt.Errorf("Failed to create hcn network: %s due to error: %v", hcnNetwork.Name, err)
 			}
-
 			logger.Info("Successfully created hcn network with response", zap.Any("hnsResponse", hnsResponse))
 		} else {
 			// we can't validate if the network already exists, don't continue
 			return nil, fmt.Errorf("Failed to create hcn network: %s, failed to query for existing network with error: %v", hcnNetwork.Name, err)
 		}
 	} else {
+		if hcnNetwork.Type == hcn.Transparent {
+			// CNI triggers Add() for new pod first and then delete older pod later
+			// for transparent network type, do not ignore network creation if network already exists
+			// return error to avoid creating second endpoint
+			logger.Error("HNS network with name already exists. Returning error for transparent network", zap.String("networkName", hcnNetwork.Name))
+			return nil, fmt.Errorf("HNS network with name:%s already exists. Returning error for transparent network", hcnNetwork.Name) //nolint
+		}
 		logger.Info("Network with name already exists", zap.String("name", hcnNetwork.Name))
 	}